CA2943638C - Production enhancement system using robot drill for drilling multi-branched fishbone and radial microholes in shale gas reservoir, and method thereof - Google Patents
Production enhancement system using robot drill for drilling multi-branched fishbone and radial microholes in shale gas reservoir, and method thereof Download PDFInfo
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- 239000002360 explosive Substances 0.000 claims description 108
- 239000007788 liquid Substances 0.000 claims description 74
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- NMJORVOYSJLJGU-UHFFFAOYSA-N methane clathrate Chemical compound C.C.C.C.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O NMJORVOYSJLJGU-UHFFFAOYSA-N 0.000 description 2
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B7/00—Special methods or apparatus for drilling
- E21B7/04—Directional drilling
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- Environmental & Geological Engineering (AREA)
- Fluid Mechanics (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Earth Drilling (AREA)
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Abstract
A production enhancement system using a robot drill for drilling multi-branched fishbone and radial microholes in shale gas reservoirs, comprising a system for a robot drill drawing coiled tubing and drilling multi-branch fishbone horizontal holes, a well-finishing system for a robot drill drawing coiled tubing and drilling small-bore branch holes, and a system for blasting and transformation in multi-branch fishbone horizontal holes. The system for a robot drill drawing coiled tubing and drilling multi-branch fishbone horizontal holes is used for drilling multilevel fishbone horizontal holes, providing a foundation for well-finishing and increasing production through blast-fracturing and transformation; the well-finishing system for a robot drill drawing coiled tubing and drilling small-bore branch holes is used for well-finishing operations in multilevel fishbone horizontal holes where drilling is completed. Also disclosed is a method for finishing well drilling and increasing production. The present production enhancement system and method realize low-cost, high-efficiency, safe, environmentally-friendly production, and avoid such drawbacks of long horizontal holes and staged, large-scale fracturing as the attendant waste of water and sand, high water pollution risks, and deep-well fracturing failure.
Description
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PRODUCTION ENHANCEMENT SYSTEM USING ROBOT DRILL FOR
DRILLING MULTI-BRANCHED FISHBONE AND RADIAL MICROHOLES
IN SHALE GAS RESERVOIR, AND METHOD THEREOF
TECHNICAL FIELD
The present invention relates to the technical field of development of unconventional oil and gas resources, in particular to a drilling, completion and production enhancement system using a drilling robot for drilling multi-branch fishbone radial microholes in a shale gas reservoir.
BACKGROUND ART
With the rapid development of national economy in China, the contradiction of energy supply and demand is increasingly conspicuous. In 2013, imported crude oil of China reached 285-million-ton, and now China has become the second largest crude oil importer in the world. The degree of dependence upon importation of crude oil has approached to 60%, which approaches or exceeds the internationally recognized energy security line. Therefore, to search for a novel alternative energy has become an important strategic measure for guaranteeing national energy security and national security while the exploration and development dynamics in the new field of a new area for oil and gas is intensified.
The exploration, development and utilization of unconventional oil and gas resources, such as shale oil and gas, coal bed gas and natural gas hydrate have a very important meaning undoubtedly for realizing energy and industry sustainable development of China. Compared with conventional natural gas, the development of shale gas has the advantages of great resource potential, long production life and long production cycle. The deposit of shale gas resources in major basins and areas of China is about 15-30 trillion cubic metres, which approximately equals with 28.3 trillion cubic metres of America and thus has a huge economic value. On the other hand, the long production cycle is also a prominent characteristic of shale gas. The production life of a shale gas field generally can reach 30-50 years, or even longer.
The latest data from United States' Geological Survey reveals that the production life of the Barnett shale gas field in Fort Worth of America can reach up to 80-100 years.
The long production life means great development and utilization values, which also determines its development potential.
A shale gas reservoir condition belongs to fractured low permeability/ultralow permeability. The production enhancement construction at the present stage mainly continues to use large-scale and massive staged sand fracturing and fracture formation for a long horizontal hole, which is relatively mature in shale gas development of America. But a development method in China has two greater drawbacks:
(1) the cost is quiet high, especially the consumption of water resources is enormous. The buried depth of shale gas of America is just about 2000 metres, and the reservoir thickness reaches hundreds of metres, such that the single-well drilling cost is less than 20 million, and the drilling completion time only needs about one week. Upon estimation, the production cost of shale gas is 1-1.27 Yuan/cubic metre.
But in Sichuan, Chongqing or other places of China, the buried depth of shale gas is 2600-3000 metres commonly, and the reservoir thickness is only tens of metres.
The single-well drilling and fracturing cost approaches to one hundred million Yuan, and the integral level of a drilling platform remarkably falls behind the advanced countries, such as America, with low intelligent and systematic levels. About three months are needed for drilling one well, so taken all together, the production cost in China is about 4-5 times of that of America, i.e., 5-6.3 Yuan/cubic metre. In addition, this method results in great construction difficulty, frequent downhole accidents, huge consumption of water and sand for fracturing ("thousand cubic metres of sand and ten thousand cubic metres of water" will be consumed in fracturing transformation of most of shale gas reservoirs), and lots of consumed water resources are unrecyclable.
Meanwhile, shale gas enrichment regions in China are mainly distributed in mountainous and hilly areas where water resources are deficient, and therefore, oil and gas developers begin to grab agricultural water, and even occupy municipal water.
Since water used in well drilling and fracturing development is injected to a shale formation which is far deeper than an aquifer, and is mainly absorbed by rock, thereby failing to be recycled. The development of shale gas resources of China faces the
PRODUCTION ENHANCEMENT SYSTEM USING ROBOT DRILL FOR
DRILLING MULTI-BRANCHED FISHBONE AND RADIAL MICROHOLES
IN SHALE GAS RESERVOIR, AND METHOD THEREOF
TECHNICAL FIELD
The present invention relates to the technical field of development of unconventional oil and gas resources, in particular to a drilling, completion and production enhancement system using a drilling robot for drilling multi-branch fishbone radial microholes in a shale gas reservoir.
BACKGROUND ART
With the rapid development of national economy in China, the contradiction of energy supply and demand is increasingly conspicuous. In 2013, imported crude oil of China reached 285-million-ton, and now China has become the second largest crude oil importer in the world. The degree of dependence upon importation of crude oil has approached to 60%, which approaches or exceeds the internationally recognized energy security line. Therefore, to search for a novel alternative energy has become an important strategic measure for guaranteeing national energy security and national security while the exploration and development dynamics in the new field of a new area for oil and gas is intensified.
The exploration, development and utilization of unconventional oil and gas resources, such as shale oil and gas, coal bed gas and natural gas hydrate have a very important meaning undoubtedly for realizing energy and industry sustainable development of China. Compared with conventional natural gas, the development of shale gas has the advantages of great resource potential, long production life and long production cycle. The deposit of shale gas resources in major basins and areas of China is about 15-30 trillion cubic metres, which approximately equals with 28.3 trillion cubic metres of America and thus has a huge economic value. On the other hand, the long production cycle is also a prominent characteristic of shale gas. The production life of a shale gas field generally can reach 30-50 years, or even longer.
The latest data from United States' Geological Survey reveals that the production life of the Barnett shale gas field in Fort Worth of America can reach up to 80-100 years.
The long production life means great development and utilization values, which also determines its development potential.
A shale gas reservoir condition belongs to fractured low permeability/ultralow permeability. The production enhancement construction at the present stage mainly continues to use large-scale and massive staged sand fracturing and fracture formation for a long horizontal hole, which is relatively mature in shale gas development of America. But a development method in China has two greater drawbacks:
(1) the cost is quiet high, especially the consumption of water resources is enormous. The buried depth of shale gas of America is just about 2000 metres, and the reservoir thickness reaches hundreds of metres, such that the single-well drilling cost is less than 20 million, and the drilling completion time only needs about one week. Upon estimation, the production cost of shale gas is 1-1.27 Yuan/cubic metre.
But in Sichuan, Chongqing or other places of China, the buried depth of shale gas is 2600-3000 metres commonly, and the reservoir thickness is only tens of metres.
The single-well drilling and fracturing cost approaches to one hundred million Yuan, and the integral level of a drilling platform remarkably falls behind the advanced countries, such as America, with low intelligent and systematic levels. About three months are needed for drilling one well, so taken all together, the production cost in China is about 4-5 times of that of America, i.e., 5-6.3 Yuan/cubic metre. In addition, this method results in great construction difficulty, frequent downhole accidents, huge consumption of water and sand for fracturing ("thousand cubic metres of sand and ten thousand cubic metres of water" will be consumed in fracturing transformation of most of shale gas reservoirs), and lots of consumed water resources are unrecyclable.
Meanwhile, shale gas enrichment regions in China are mainly distributed in mountainous and hilly areas where water resources are deficient, and therefore, oil and gas developers begin to grab agricultural water, and even occupy municipal water.
Since water used in well drilling and fracturing development is injected to a shale formation which is far deeper than an aquifer, and is mainly absorbed by rock, thereby failing to be recycled. The development of shale gas resources of China faces the
2 problems of water deficiency and high cost, thereby severely restricting the development of the shale gas industry.
(2) The development difficulty of deep shale gas reservoirs is great, and it is hard to satisfy the requirements for fracturing construction parameters. The buried depths of deep shale gas reservoirs of China are all over 4000 metres (for example, the buried depth of a production layer section of the shale gas reservoir in Ziliujing Formation of Yuanba Block in Sichuan Basin is 4110 metres), which far exceeds the standard range (76-2440 metres) of a common shale gas formation of America. For various technical problems of deep shale gas reservoirs, such as relatively deep buried depth, considerably compact shale, relatively high pressure coefficient (the formation pressure coefficient is generally about 2.0), high formation fracturing pressure gradient, high friction resistance, high-volume pumping, high pump pressure in ground construction (the ground pressure in conventional low-volume acidizing construction in such areas is 70-95MPa) and difficulty to control volume and pressure during construction, the conventional staged fracturing technology for a horizontal hole is very difficult to fracture the formation and achieve a better transformation effect. Therefore, it is urgent to obtain a high-efficiency, convenient and economic production enhancement and transformation method in the field of the development of shale gas reservoirs.
At present, coiled tubing are widely applied in downhole operations, such well drilling, oil production, perforation, fracturing and well logging in both China and abroad, and all, aspects of technologies are mature increasingly. On the other hand, drilling robot technologies, especially petroleum pipeline robots and oil and gas drilling robots develop rapidly at present, and play a significant role in various actual engineering by virtue of their peculiar advantages, such as small size, high power, high operation precision, high adaptability and capability of carrying multiple special downhole operation tools. So, this makes it possible to finish high-precision complex downhole operations under the conjunction of coiled tubing and the drilling robots.
A multi-branch fishbone horizontal hole technology is a novel drilling and completion technology which aims to release a reservoir on the premise of drilling
(2) The development difficulty of deep shale gas reservoirs is great, and it is hard to satisfy the requirements for fracturing construction parameters. The buried depths of deep shale gas reservoirs of China are all over 4000 metres (for example, the buried depth of a production layer section of the shale gas reservoir in Ziliujing Formation of Yuanba Block in Sichuan Basin is 4110 metres), which far exceeds the standard range (76-2440 metres) of a common shale gas formation of America. For various technical problems of deep shale gas reservoirs, such as relatively deep buried depth, considerably compact shale, relatively high pressure coefficient (the formation pressure coefficient is generally about 2.0), high formation fracturing pressure gradient, high friction resistance, high-volume pumping, high pump pressure in ground construction (the ground pressure in conventional low-volume acidizing construction in such areas is 70-95MPa) and difficulty to control volume and pressure during construction, the conventional staged fracturing technology for a horizontal hole is very difficult to fracture the formation and achieve a better transformation effect. Therefore, it is urgent to obtain a high-efficiency, convenient and economic production enhancement and transformation method in the field of the development of shale gas reservoirs.
At present, coiled tubing are widely applied in downhole operations, such well drilling, oil production, perforation, fracturing and well logging in both China and abroad, and all, aspects of technologies are mature increasingly. On the other hand, drilling robot technologies, especially petroleum pipeline robots and oil and gas drilling robots develop rapidly at present, and play a significant role in various actual engineering by virtue of their peculiar advantages, such as small size, high power, high operation precision, high adaptability and capability of carrying multiple special downhole operation tools. So, this makes it possible to finish high-precision complex downhole operations under the conjunction of coiled tubing and the drilling robots.
A multi-branch fishbone horizontal hole technology is a novel drilling and completion technology which aims to release a reservoir on the premise of drilling
3 safely and protecting the reservoir and has the capability of drilling multiple branch holes and performing well completion on a primary hole along an area side with better reservoir characteristics in a horizontal hole. By means of this technology, maximum effective footage of the reservoir can be realized.
Fasting-curing liquid explosives have been widely applied in numerous industrial blasting by means of their advantages, such as high blasting energy, small size, low cost, convenience in transportation and fast thickening. The accurate directional blasting technology has been mature considerably, and has played an important role in coal, demolition and petroleum industries. In addition, in production enhancement and development of petroleum, fundamental researches on blast-fracturing in formation, fracture network formation and supporting mechanisms, blast-fracturing and production enhancement principles and the like have been quite sophisticated.
This makes it possible to reconstruct shale gas resources efficiently, conveniently and economically by the way of blast-fracturing to form fracture networks.
TECHNICAL PROBLEMS
The invention aims to overcoming the drawbacks in the prior art and provide a drilling and completion and production enhancement system and method using drilling robots for drilling multi-branch fishbone radial microholes in a shale gas reservoir. In accordance with one aspect, there is provided A drilling, completion and production enhancement system for use in a shale gas reservoir, the system comprising a coiled tubing; a drilling system to drill a fishbone-shaped multi-branch horizontal well, the drilling system comprising a drilling robot A and a drilling tool, wherein the drilling tool is provided at a front end of the drilling robot A
and comprises a first centralizer, a jar and a drill bit which are sequentially connected, and the coiled tubing is connected to the drilling robot A at a rear end of the drilling robot A and cooperates with the drilling robot A to drill the fishbone-shaped multi-branch horizontal well by the use of the drilling tool; a slim hole completion system for use in the fishbone-shaped multi-branch horizontal well, the slim hole completion system comprising a drilling robot B and a well completion tool, wherein the well completion
Fasting-curing liquid explosives have been widely applied in numerous industrial blasting by means of their advantages, such as high blasting energy, small size, low cost, convenience in transportation and fast thickening. The accurate directional blasting technology has been mature considerably, and has played an important role in coal, demolition and petroleum industries. In addition, in production enhancement and development of petroleum, fundamental researches on blast-fracturing in formation, fracture network formation and supporting mechanisms, blast-fracturing and production enhancement principles and the like have been quite sophisticated.
This makes it possible to reconstruct shale gas resources efficiently, conveniently and economically by the way of blast-fracturing to form fracture networks.
TECHNICAL PROBLEMS
The invention aims to overcoming the drawbacks in the prior art and provide a drilling and completion and production enhancement system and method using drilling robots for drilling multi-branch fishbone radial microholes in a shale gas reservoir. In accordance with one aspect, there is provided A drilling, completion and production enhancement system for use in a shale gas reservoir, the system comprising a coiled tubing; a drilling system to drill a fishbone-shaped multi-branch horizontal well, the drilling system comprising a drilling robot A and a drilling tool, wherein the drilling tool is provided at a front end of the drilling robot A
and comprises a first centralizer, a jar and a drill bit which are sequentially connected, and the coiled tubing is connected to the drilling robot A at a rear end of the drilling robot A and cooperates with the drilling robot A to drill the fishbone-shaped multi-branch horizontal well by the use of the drilling tool; a slim hole completion system for use in the fishbone-shaped multi-branch horizontal well, the slim hole completion system comprising a drilling robot B and a well completion tool, wherein the well completion
4 tool is provided at a front end of the drilling robot B and comprises a float shoe, a float collar, a magnetic locater sub, and a second centralizer which are sequentially connected within a bushing, and the coiled tubing is connected to the drilling robot B
at a rear end of the drilling robot B and cooperates with the drilling robot B
to complete the fishbone-shaped multi-branch horizontal well by the use of the well completion tool; and a blasting reconstruction system for use in the fishbone-shaped multi-branch horizontal well completed by the slim hole completion system, the blasting reconstruction system comprising a drilling robot C being connected to the coiled tubing at a rear end of the drilling robot C; a multifunctional thin-walled housing having an explosive tube cavity to be filled with a fast curing liquid explosive, the explosive tube cavity comprising a spray nozzle at its head, a one-way valve and a detonator; a piston cylinder which is provided between a front end of the drilling robot C and a tail of the multifunctional thin-walled housing and provides a hydraulic pressure to force the liquid explosive within the explosive tube cavity to open the spray nozzle thus allowing the spraying of the liquid explosive; and a connector separable under an electric control which is provided between a tail of the explosive tube cavity and the drilling robot C, wherein the connector is powered off upon the completion of the spraying of the liquid explosive to retain the multifunctional thin-walled housing at a bottom of the fishbone-shaped multi-branch well, and the drilling robot C is detached from the multifunctional thin-walled housing and is pulled out of the fishbone-shaped multi-branch well together with the coiled tubing.
In accordance with another aspect, a plurality of fishbone multilevel branched horizontal holes are drilled in a horizontal section of a horizontal hole by the matching of coiled tubing and a drilling robot. Then, the well completion operation is carried out on the branch hole where drilling is completed by the matching of coiled tubing and a drilling robot. Later, fast-curing liquid explosive is carried by the matching of coiled tubing and a drilling robot and sprayed to each of the fishbone multilevel branched horizontal holes, and is then detonated to blast the shale formation to form fractures, thereby achieving the purposes of transformation and production enhancement of shale gas reservoirs.
4a TECHNICAL SOLUTIONS
The purpose of the present invention is achieved by the following technical solutions: a drilling and completion and production enhancement system using a drilling robot for drilling multi-branch fishbone radial microholes in a shale gas reservoir comprises a system for drilling multi-branch fishbone horizontal holes by the matching of coiled tubing and a drilling robot, a well-completion system for microholes of a branch hole by the matching of coiled tubing and the drilling robot, and a system for blasting and transforming the multi-branch fishbone horizontal holes.
The system for drilling the multi-branch fishbone horizontal holes by the matching of the coiled tubing and the drilling robot is used for drilling fishbone multilevel branched horizontal holes of the shale gas reservoir so as to provide a foundation for well-completion and production enhancement through explosive fracturing transformation. The well-completion system for microholes of the branch hole by the matching of the coiled tubing and the drilling robot is used for carrying out well-completion construction on the multi-branch fishbone horizontal holes where drilling is completed. The system for blasting and transforming the multi-branch fishbone horizontal holes is used for spraying the fast-curing liquid explosive in the fishbone branch holes and realizing production enhancement by blasting.
The system for drilling the multi-branch fishbone horizontal holes by the matching of the coiled tubing and the drilling robot consists of coiled tubing, a drilling robot A and a drilling tool, wherein the drilling tool is provided at the front end of the drilling robot A and consists of a centralizer, a drilling jar and a drilling bit which are sequentially connected;
the well-completion system for microholes of the branch hole by the matching of the coiled tubing and the drilling robot consists of coiled tubing, a drilling robot B and a well-completion tool, wherein the well-completion tool is provided at the front end of the drilling robot B and comprises a float shoe, a float collar, a magnetic locator suband a centralizer which are sequentially connected within a bushing;
the system for blasting and transforming the multi-branch fishbone horizontal
at a rear end of the drilling robot B and cooperates with the drilling robot B
to complete the fishbone-shaped multi-branch horizontal well by the use of the well completion tool; and a blasting reconstruction system for use in the fishbone-shaped multi-branch horizontal well completed by the slim hole completion system, the blasting reconstruction system comprising a drilling robot C being connected to the coiled tubing at a rear end of the drilling robot C; a multifunctional thin-walled housing having an explosive tube cavity to be filled with a fast curing liquid explosive, the explosive tube cavity comprising a spray nozzle at its head, a one-way valve and a detonator; a piston cylinder which is provided between a front end of the drilling robot C and a tail of the multifunctional thin-walled housing and provides a hydraulic pressure to force the liquid explosive within the explosive tube cavity to open the spray nozzle thus allowing the spraying of the liquid explosive; and a connector separable under an electric control which is provided between a tail of the explosive tube cavity and the drilling robot C, wherein the connector is powered off upon the completion of the spraying of the liquid explosive to retain the multifunctional thin-walled housing at a bottom of the fishbone-shaped multi-branch well, and the drilling robot C is detached from the multifunctional thin-walled housing and is pulled out of the fishbone-shaped multi-branch well together with the coiled tubing.
In accordance with another aspect, a plurality of fishbone multilevel branched horizontal holes are drilled in a horizontal section of a horizontal hole by the matching of coiled tubing and a drilling robot. Then, the well completion operation is carried out on the branch hole where drilling is completed by the matching of coiled tubing and a drilling robot. Later, fast-curing liquid explosive is carried by the matching of coiled tubing and a drilling robot and sprayed to each of the fishbone multilevel branched horizontal holes, and is then detonated to blast the shale formation to form fractures, thereby achieving the purposes of transformation and production enhancement of shale gas reservoirs.
4a TECHNICAL SOLUTIONS
The purpose of the present invention is achieved by the following technical solutions: a drilling and completion and production enhancement system using a drilling robot for drilling multi-branch fishbone radial microholes in a shale gas reservoir comprises a system for drilling multi-branch fishbone horizontal holes by the matching of coiled tubing and a drilling robot, a well-completion system for microholes of a branch hole by the matching of coiled tubing and the drilling robot, and a system for blasting and transforming the multi-branch fishbone horizontal holes.
The system for drilling the multi-branch fishbone horizontal holes by the matching of the coiled tubing and the drilling robot is used for drilling fishbone multilevel branched horizontal holes of the shale gas reservoir so as to provide a foundation for well-completion and production enhancement through explosive fracturing transformation. The well-completion system for microholes of the branch hole by the matching of the coiled tubing and the drilling robot is used for carrying out well-completion construction on the multi-branch fishbone horizontal holes where drilling is completed. The system for blasting and transforming the multi-branch fishbone horizontal holes is used for spraying the fast-curing liquid explosive in the fishbone branch holes and realizing production enhancement by blasting.
The system for drilling the multi-branch fishbone horizontal holes by the matching of the coiled tubing and the drilling robot consists of coiled tubing, a drilling robot A and a drilling tool, wherein the drilling tool is provided at the front end of the drilling robot A and consists of a centralizer, a drilling jar and a drilling bit which are sequentially connected;
the well-completion system for microholes of the branch hole by the matching of the coiled tubing and the drilling robot consists of coiled tubing, a drilling robot B and a well-completion tool, wherein the well-completion tool is provided at the front end of the drilling robot B and comprises a float shoe, a float collar, a magnetic locator suband a centralizer which are sequentially connected within a bushing;
the system for blasting and transforming the multi-branch fishbone horizontal
5 =
holes consists of coiled tubing, a drilling robot C and a multifunctional fast-curing liquid explosive thin-walled housing, wherein an explosive tube cavity of the multifunctional fast-curing liquid explosive thin-walled housing is filled with a fast-curing liquid explosive. A piston cylinder is provided between the front end of the drilling robot C and the tail of the multifunctional fast-curing liquid explosive thin-walled housing. A nozzle of the explosive tube cavity can be opened by means of the hydraulic pressure provided by the piston cylinder under the thrust of the liquid, such that the explosive is sprayed out. A connector which can be separated under the control of electric power and hydraulic pressure is provided between the tail of the explosive tube cavity and the front end of the drilling robot C. After the drilling robot C sprays the fast-curing liquid explosive completely, the connector is powered off, such that the multifunctional fast-curing liquid explosive thin-walled housing is reserved at the bottom of the branched fishbone well. The drilling robot C is drawn out along with the coiled tube. A one-way valve is provided in front of the explosive tube cavity, and a detonating device is provided at the upper part of the explosive tube cavity; and the drilling robot A, the drilling robot B and the drilling robot C are identical in structure. Each drilling robot is equipped with an active driving device for driving the drilling robot to move autonomously and is internally provided with a passageway for pump injection of liquid during drilling and completion, transformation by blasting and stable production at the late stage. One end of the coiled tube is connected with ground support equipment, and the other end of the coiled tube is communicated with the passageway of the drilling robot.
The drilling tool of the drilling robot is equipped with multiple sensors which are used for monitoring downhole conditions, downhole positioning and downhole operations.
An adaptive joint is provided at the front end and the rear end of each of the drilling robots respectively, wherein one adaptive joint is connected with an electrohydraulic channel of the coiled tubing, and the other one is connected with the multifunctional fast-curing liquid explosive thin-walled housing through the drilling
holes consists of coiled tubing, a drilling robot C and a multifunctional fast-curing liquid explosive thin-walled housing, wherein an explosive tube cavity of the multifunctional fast-curing liquid explosive thin-walled housing is filled with a fast-curing liquid explosive. A piston cylinder is provided between the front end of the drilling robot C and the tail of the multifunctional fast-curing liquid explosive thin-walled housing. A nozzle of the explosive tube cavity can be opened by means of the hydraulic pressure provided by the piston cylinder under the thrust of the liquid, such that the explosive is sprayed out. A connector which can be separated under the control of electric power and hydraulic pressure is provided between the tail of the explosive tube cavity and the front end of the drilling robot C. After the drilling robot C sprays the fast-curing liquid explosive completely, the connector is powered off, such that the multifunctional fast-curing liquid explosive thin-walled housing is reserved at the bottom of the branched fishbone well. The drilling robot C is drawn out along with the coiled tube. A one-way valve is provided in front of the explosive tube cavity, and a detonating device is provided at the upper part of the explosive tube cavity; and the drilling robot A, the drilling robot B and the drilling robot C are identical in structure. Each drilling robot is equipped with an active driving device for driving the drilling robot to move autonomously and is internally provided with a passageway for pump injection of liquid during drilling and completion, transformation by blasting and stable production at the late stage. One end of the coiled tube is connected with ground support equipment, and the other end of the coiled tube is communicated with the passageway of the drilling robot.
The drilling tool of the drilling robot is equipped with multiple sensors which are used for monitoring downhole conditions, downhole positioning and downhole operations.
An adaptive joint is provided at the front end and the rear end of each of the drilling robots respectively, wherein one adaptive joint is connected with an electrohydraulic channel of the coiled tubing, and the other one is connected with the multifunctional fast-curing liquid explosive thin-walled housing through the drilling
6 tool and the well-completion tool.
The ground support equipment is a coiled tubing operation platform or a coiled tubing operation vehicle.
The detonating device is connected with ground control equipment through a detonating line on the detonating device.
The drilling and completion and production enhancement method using a drilling robot for drilling multi-branch fishbone radial microholes in a shale gas reservoir comprises the following steps: S I -S6:
Si. design of an overall solution: designing an overall well body structure, a drilling solution, a well-completion solution and production enhancement through blast-fracturing of each multi-branch fishbone horizontal hole;
S2. drilling of the fishbone multi-branch holes: setting coiled tubing and drilling robot system that carries a drilling tool into a horizontal section of the horizontal hole where drilling is completed, and drilling a plurality of fishbone multi-branch holes through the coiled tubing and the drilling robot according to the design;
S3. well cementation at the bottom of the fishbone multi-branch holes or direct well completion with naked eyes: drawing out the coiled tube and the drilling robot that carry the drilling tool, then replacing the drilling tool with a well cementation tool and a bushing, and later setting the well cementation tool and the bushing to the bottom of the fishbone branch hole to finish well cementation;
S4. blasting preparation by spraying explosive to the bottom of the fishbone branch hole: installing the fast-curing liquid explosive thin-walled housing on the coiled tubing and the drilling robot, setting the coiled tube and the drilling robot to the bottom of the fishbone branch hole, spraying fast-curing explosive through the coiled tubing and the drilling robot and preparing blasting;
S5. production enhancement by blasting: drawing out the coiled tubing and other auxiliary tools first, then detonating the explosive on the bottom to fracture rock of the shale gas reservoir, such that more shale gas stored in shale may be gathered to the wellhole to realize low-cost, high-efficiency, safe and environmentally-friendly production of the shale gas; and
The ground support equipment is a coiled tubing operation platform or a coiled tubing operation vehicle.
The detonating device is connected with ground control equipment through a detonating line on the detonating device.
The drilling and completion and production enhancement method using a drilling robot for drilling multi-branch fishbone radial microholes in a shale gas reservoir comprises the following steps: S I -S6:
Si. design of an overall solution: designing an overall well body structure, a drilling solution, a well-completion solution and production enhancement through blast-fracturing of each multi-branch fishbone horizontal hole;
S2. drilling of the fishbone multi-branch holes: setting coiled tubing and drilling robot system that carries a drilling tool into a horizontal section of the horizontal hole where drilling is completed, and drilling a plurality of fishbone multi-branch holes through the coiled tubing and the drilling robot according to the design;
S3. well cementation at the bottom of the fishbone multi-branch holes or direct well completion with naked eyes: drawing out the coiled tube and the drilling robot that carry the drilling tool, then replacing the drilling tool with a well cementation tool and a bushing, and later setting the well cementation tool and the bushing to the bottom of the fishbone branch hole to finish well cementation;
S4. blasting preparation by spraying explosive to the bottom of the fishbone branch hole: installing the fast-curing liquid explosive thin-walled housing on the coiled tubing and the drilling robot, setting the coiled tube and the drilling robot to the bottom of the fishbone branch hole, spraying fast-curing explosive through the coiled tubing and the drilling robot and preparing blasting;
S5. production enhancement by blasting: drawing out the coiled tubing and other auxiliary tools first, then detonating the explosive on the bottom to fracture rock of the shale gas reservoir, such that more shale gas stored in shale may be gathered to the wellhole to realize low-cost, high-efficiency, safe and environmentally-friendly production of the shale gas; and
7 S6. stable production at the late stage.
In the S4, the thin-walled housing filled with the fast-curing liquid explosive is fed to the bottom of the fishbone branch hole by the matching of the coiled tubing and the drilling robot.
In the S4, liquid is pumped in through the coiled tubing to pressurize the tail of the multifunctional fast-curing liquid explosive thin-walled housing to a predetermined value, so that the liquid explosive in the thin-walled housing is sprayed to the bottom of the fishbone branch hole through the nozzle at the front end of the explosive tube cavity.
In the S5, a ground detonating device sends a detonating signal to the detonating device on the explosive tube cavity to realize detonating, such that rock fractures to form a fracture network, thereby achieving the purpose of low-cost, high-efficiency, safe and environmentally-friendly production enhancement and development of shale gas.
BENEFICIAL EFFECTS
The present invention has the following advantages: (1) production enhancement and transformation operations can be finished conveniently and rapidly, various preparation works in the early stage of original fracturing transformation are greatly simplified, and only multifunctional coiled tubing operation vehicles and robots which are convenient to move, dismantle and set up/down are used to participate in operations, without the needs of paying huge investment for purchasing and transporting fracturing sand and fracturing liquid, and assembling and installing a fracture pump vehicle set, or the like. (2) The branch holes may be scientifically managed and blasted in different stages according to different development designs, to furthest improve the recovery ratio and realize stable production well. (3) In relatively deep shale gas reservoirs (the well depth exceeds 4000 metres) which are difficult to develop through conventional methods, by means of the present invention, shale can be fractured well to generate fractures having high flow conductivity, such that the use of most of the deep shale gas resources that cannot be developed by
In the S4, the thin-walled housing filled with the fast-curing liquid explosive is fed to the bottom of the fishbone branch hole by the matching of the coiled tubing and the drilling robot.
In the S4, liquid is pumped in through the coiled tubing to pressurize the tail of the multifunctional fast-curing liquid explosive thin-walled housing to a predetermined value, so that the liquid explosive in the thin-walled housing is sprayed to the bottom of the fishbone branch hole through the nozzle at the front end of the explosive tube cavity.
In the S5, a ground detonating device sends a detonating signal to the detonating device on the explosive tube cavity to realize detonating, such that rock fractures to form a fracture network, thereby achieving the purpose of low-cost, high-efficiency, safe and environmentally-friendly production enhancement and development of shale gas.
BENEFICIAL EFFECTS
The present invention has the following advantages: (1) production enhancement and transformation operations can be finished conveniently and rapidly, various preparation works in the early stage of original fracturing transformation are greatly simplified, and only multifunctional coiled tubing operation vehicles and robots which are convenient to move, dismantle and set up/down are used to participate in operations, without the needs of paying huge investment for purchasing and transporting fracturing sand and fracturing liquid, and assembling and installing a fracture pump vehicle set, or the like. (2) The branch holes may be scientifically managed and blasted in different stages according to different development designs, to furthest improve the recovery ratio and realize stable production well. (3) In relatively deep shale gas reservoirs (the well depth exceeds 4000 metres) which are difficult to develop through conventional methods, by means of the present invention, shale can be fractured well to generate fractures having high flow conductivity, such that the use of most of the deep shale gas resources that cannot be developed by
8 original hydraulic fracturing is made to come true. (4) Equipment is greatly simplified by using three operation systems formed by the matching of the coiled tubing and the drilling robots, an original large-scale fracturing method which depends on a ground high-pressure pump vehicle is creatively changed to drill multilevel fishbone branch holes, and the fast-curing liquid explosive is used in the fishbone branch holes to perform directional blasting to fracture the shale reservoir, thereby achieving high-efficiency, environmentally-friendly, convenient and low-cost production of shale gas.
BRIEF DESCRIPTION TO THE DRAWINGS
Figure 1 is a schematic drawing of a construction flow according to the present invention;
Figure 2 is a structural schematic drawing in which multi-branch fishbone horizontal holes are drilled according to the present invention;
Figure 3 is a locally enlarged view during well-completion construction of microholes according to the present invention;
Figure 4 is a locally enlarged view during production enhancement and transformation by fracturing according to the present invention; and In drawings, ground supporting equipment 1, horizontal hole 2, coiled tubing 3, bushing 4, fishbone branch hole 5, drilling robot A 61, drilling robot B 62, drilling robot C 63, drilling tool 7, cement injection tool 8 for bushing of branch hole, cement ring 9 for branch hole, multifunctional thin-walled housing 10, nozzle 11 and piston cylinder 12 are illustrated.
DETAILED DESCRIPTION OF THE EMBODIMENTS
The present invention is further described as below in conjunction with the drawings, and the protection scope of the present invention is not limited to the followings:
as show in Figure 1, a drilling and completion and production enhancement system using a drilling robot A 61 for drilling multi-branch fishbone radial microholes in a shale gas reservoir, comprising a system for drilling multi-branch fishbone
BRIEF DESCRIPTION TO THE DRAWINGS
Figure 1 is a schematic drawing of a construction flow according to the present invention;
Figure 2 is a structural schematic drawing in which multi-branch fishbone horizontal holes are drilled according to the present invention;
Figure 3 is a locally enlarged view during well-completion construction of microholes according to the present invention;
Figure 4 is a locally enlarged view during production enhancement and transformation by fracturing according to the present invention; and In drawings, ground supporting equipment 1, horizontal hole 2, coiled tubing 3, bushing 4, fishbone branch hole 5, drilling robot A 61, drilling robot B 62, drilling robot C 63, drilling tool 7, cement injection tool 8 for bushing of branch hole, cement ring 9 for branch hole, multifunctional thin-walled housing 10, nozzle 11 and piston cylinder 12 are illustrated.
DETAILED DESCRIPTION OF THE EMBODIMENTS
The present invention is further described as below in conjunction with the drawings, and the protection scope of the present invention is not limited to the followings:
as show in Figure 1, a drilling and completion and production enhancement system using a drilling robot A 61 for drilling multi-branch fishbone radial microholes in a shale gas reservoir, comprising a system for drilling multi-branch fishbone
9 horizontal holes by the matching of coiled tubing 3 and a drilling robot A 61, a well-completion system for microholes of branch holes by the matching of coiled tubing 3 and a drilling robot B 62, and a system for blasting and transforming the multi-branch fishbone horizontal holes. The system for drilling the multi-branch fishbone horizontal holes by the matching of the coiled tubing 3 and the drilling robot A 61 is used for drilling fishbone multilevel branched horizontal holes of the shale gas reservoir so as to provide a foundation for well-completion and transformation and production enhancement through blast-fracturing; the well-completion system for microholes of the branch holes by the matching of the coiled tubing 3 and the drilling robot B 62 is used for carrying out well-completion construction on the fishbone multilevel branched horizontal holes where drilling is completed; and the system for blasting and transforming the multi-branch fishbone horizontal holes is used for spraying the fast-curing liquid explosive in the fishbone branch holes and realizing production enhancement by blasting;
As shown in Figure 2, the system for drilling the multi-branch fishbone horizontal holes by the matching of the coiled tubing 3 and the drilling robot A 61 is used for drilling fishbone multilevel branched horizontal holes of the shale gas reservoir so as to provide a foundation for subsequent well-completion and production enhancement through blast-fracturing transformation and consists of coiled tubing 3, a drilling robot A 61 and a drilling tool 7, wherein the drilling tool 7 is provided at the front end of the drilling robot A 61 and consists of a centralizer, a drilling jar and a drilling bit which are sequentially connected;
As shown in Figure 3, the well-completion system for microholes of the branch hole by the matching of the coiled tubing 3 and the drilling robot A 62 is used for carrying out well-completion construction on the fishbone multilevel branched horizontal holes where drilling is completed to make preparations for high-efficiency, safe and low-cost production enhancement by blasting fracturing transformation, and consists of coiled tubing 3, a drilling robot B 62 and a well-completion tool, wherein the well-completion tool is provided at the front end of the drilling robot B
62 and comprising a float shoe, a float collar, a magnetic locator suband a centralizer which are sequentially connected within a bushing 4;
As shown in Figure 4, the system for blasting and transforming the multi-branch fishbone horizontal holes consists of coiled tubing 3, a drilling robot C 63 and a multifunctional fast-curing liquid explosive thin-walled housing 10, wherein an explosive tube cavity of the multifunctional fast-curing liquid explosive thin-walled housing 10 is filled with a fast-curing liquid explosive; a piston cylinder 12 is provided between the front end of the drilling robot C 63 and the tail of the multifunctional fast-curing liquid explosive thin-walled housing10; a nozzle 11 of the explosive tube cavity can be opened by means of means of the hydraulic pressure provided by the piston cylinder 12 under the thrust of the liquid, such that the explosive is sprayed out; a connector which can be separated under the control of electric power and hydraulic pressure is provided between the tail of the explosive tube cavity and the front end of the drilling robot C 63; after the drilling robot C 63 sprays the fast-curing liquid explosive completely, the connector is powered off, such that the multifunctional fast-curing liquid explosive thin-walled housing 10 is reserved at the bottom of the branched fishbone well 5; the drilling robot C
63 is drawn out along with the coiled tube 3; and a one-way valve is provided in front of the explosive tube cavity. A detonating device is provided at the upper part of the explosive tube cavity. The detonating device is connected with ground control equipment through a detonating line on the detonating device.
The drilling robot A 61, the drilling robot B 62 and the drilling robot C 63 are identical in structure. Each drilling robot is equipped with an active driving device for driving the drilling robot to move autonomously, wherein the active driving device can realize a self-driving function under the electric power provided by the coiled tubing 3, and can be set down by matching with the coiled tubing 3 to provide the drilling pressure in a deep well section where the coiled tubing 3 cannot provide sufficient setting force. Each drilling robot is internally provided with a passageway for pump injection of liquid during drilling and completion, blasting transformation and stable production at the late stage. One end of the coiled tube 3 is connected with ground support equipment, and the other end of the coiled tube 3 is communicated =
with the passageway. A piston is provided in the passageway and separates the passageway of the robot apart from the explosive tube cavity.
The drilling tool 7 of the drilling robot is equipped with multiple sensors which are used for monitoring downhole conditions, downhole positioning and downhole operations. The drilling robot has relatively high anti-sliding and waterproof operation capability under extreme environments, and specially can operate reliably in a wellhole filled with drilling fluid. The drilling robot has an oriented walking mechanism which ensures that the drilling robot can accurately walk to a specific position in the fishbone multi-branch wellhole.
An adaptive joint is provided at the front end and the rear end of each of the drilling robots respectively, wherein one adaptive joint is connected with an electrohydraulic channel of the coiled tubing 3, and the other one is connected with the multifunctional fast-curing liquid explosive thin-walled housing 10 through the drilling tool 7 and the well-completion tool.
The detonating device must satisfy the following requirements: the fast-curing liquid explosive is safe and easy to transport, and is safe, reliable, easy to control and large in blasting energy in extremely severe environments of high temperature and high pressure in a deep well; the fast-curing liquid explosive has good flowability in a liquid state and small friction to a manifold and is convenient to spray; the fast-curing liquid explosive can be fast attached and cured after being sprayed to rack;
and the explosive has good compatibility with a detonating pipeline, and the detonating pipeline is easy to install, unlikely to be damaged and suitable for long-distance detonation in a deep well.
The multi-functional fast-curing liquid explosive thin-walled housing 10 must satisfy the followings: the thin-walled housing has better compatibility with the downhole drilling robots and the coiled tubing; the thin-walled housing is cylindrical and hollow integrally, and is used for storing explosive, and six fin-shaped metal ribs are disposed outside the housing and used for protecting the housing body from being abraded, scraped and damaged by the wellhole wall in the process of moving underground; the housing can withstand relatively large pressure and relatively high temperature by means of its material, and can work reliably in a deep well over 4000 metres; the wall of the housing is thin, high in strength and unlikely to be damaged;
the tail of the thin-walled housingis connected with the liquid passageway in the drilling robot C; the piston is arranged in the front of the passageway at the tail to separate the passageway of the drilling robot C apart from the explosive cavity, and has good sealability after the explosive is charged, thus ensuring that liquid from the coiled tubing cannot flow into the explosive tube cavity; the piston can slidably extrude the liquid explosive in the explosive tube cavity under a certain liquid pressure to achieve the purpose that the liquid explosive is sprayed out by extruding;
and the thin-walled housing has a multifunctional special nozzle which is large in spraying area, is capable of freely rotating in the spraying process and is anti-clogging.
The drilling tool 7 must satisfy the followings: the drilling tool 7 has favorable compatibility with the coiled tubing and the drilling robots, and adopts an electrically-driven or hydraulically-driven drill bit; a deflecting tool can be mounted conveniently, such that qualified fishbone multi-branch holes may be drilled accurately according to design angles; the drill bit has good wear resistance and high mechanism reliability and can satisfy one-time drilling of all or multiple designed fishbone multi-branch holes; the centralizer ensures smooth drilling to a target in a vertical well section without deflecting; and a cuttings and drilling fluid return passageway is reserved in a shell of the drilling tool, thereby ensuring that chippings can be carried to the ground rapidly and smoothly.
The coiled tubing 3 must satisfy the followings: the coiled tubing is an electrohydraulic composite tubing which can supply necessary driving power, liquid energy, electric power and substances for a downhole system; the coiled tubing has the normal working hole depth which should reach over 4000 metres, and is unlikely to failure due to fatigue wear and suitable for multiple downhole operations;
and the coiled tubing has good compatibility with other downhole tools, and can be matched with the drilling robots reliably so as to supply electric power and liquid energy for the drilling robots.
The drilling robot A 61 in the system for drilling the multi-branch fishbone horizontal holes by the matching of the coiled tubing and the drilling robot must satisfy the followings: the coiled tubing may be connected with the drilling robot A 61 so as to supply liquid energy and electric power to the coiled tubing; the drilling robot A 61 has an oriented walking mechanism which ensures that the drilling robot can accurately walk to a specific position in the fishbone multi-branch wellhole;
the drilling robot A 61 can carry various sensors which are matched with the drilling tool and used for monitoring downhole conditions, positioning, downhole operations and the like; the drilling robot A 61 has relatively strong traction ability and can be matched with the coiled tubing to provide a drilling pressure for the drilling tool so as to realize the purpose of drilling to a target section efficiently and safely;
the drilling robot A 61 has relatively high anti-sliding and waterproof operation capabilities under extreme downhole environments, and especially in a wellhole filled with drilling fluid;
and the drilling robot A 61 is cylindrical and reserved with a liquid passageway, wherein the tail of the drilling robot A 61 is connected with the coiled tubing and the head of the drilling robot A 61 is connected with the corresponding drilling tool.
The drilling robot C 61 in the system for blasting and transforming the multi-branch fishbone horizontal holes must satisfy the followings: the front end of the drilling robot C 61 is connected with the piston cylinder at the tail of the multifunctional fast-curing liquid explosive thin-walled housing and provides hydraulic energy therefor, such that the nozzle at the front end of the explosive tube cavity can be opened under the action of the liquid thrust as designed, and then the explosive in the tube cavity is sprayed out; the conjunction between the front end of the drilling robot and the tail of the explosive tube cavity may be out of connection under the control of electric power or hydraulic pressure, such that the drilling robot retains the thin-walled housing at the bottom of the branch hole after the fast-curing liquid explosive is sprayed out, and then the drilling robot may be drawn out along with the coiled tubing.
Furthermore, blasting and production enhancement operations can be finished efficiently and safely in the system for blasting and transforming the multi-branch fishbone horizontal holes. Equipment and pipelines for the detonating system, and the type selection and design quantity of the fast-curing liquid explosive also must satisfy the corresponding requirements as follows: the fast-curing liquid explosive is safe and easy to transport, and is safe, reliable, easy to control and large in blasting energy in extremely severe environments of high temperature and high pressure in a deep well:
the fast-curing liquid explosive has good flowability in a liquid state and small friction to a manifold and is convenient to spray; the fast-curing liquid explosive can be fast attached and cured after being sprayed to rack; and the explosive has good compatibility with a detonating pipeline, and the detonating pipeline is easy to install, unlikely to be damaged and suitable for long-distance detonation in a deep well.
A drilling and completion and production enhancement method using a drilling robot for drilling multi-branch fishbone radial microholes in a shale gas reservoir comprises the following steps: SI-S6:
S1 . design of an overall solution: designing an overall well body structure, a drilling solution, a well-completion solution and production enhancement through blast-fracturing of each multi-branch fishbone horizontal hole; and this step mainly includes designs of a drilling and completion solution and a solution of production enhancement by blasting, and device installation and pipeline layout of the coiled tubing 3 on the wellhead. Furthermore, the step Si also make preparations for next constructions, i.e., solution formulation, dispatching of equipment to the site, assembly of coiled tubing operation system, installation of an assorted wellhead device, installation of the drilling tool on the coiled tube and drilling robot A 61, before production enhancement, development and construction of shale gas.
It is necessary to consider the size and morphology of the shale gas reservoir and sufficiently cognize the geology in terms of the solution design, so that the branch hole can communicate an oil and gas reservoir of a relatively large scale as much as possible to facilitate next development of blast-fracturing. First, the well type design includes: quantity design of fishbone branch holes 5, symmetric and asymmetric arrangement, a distance between every two adjacent branches, included angles between branch holes and the primary well, well depth of each fishbone branch hole 5 and the like, all of which should be made by sufficiently arguing the liberation degree of the designed well type to the productivity through combining geological knowledge and using computer engineering simulation.
A directional blasting design is carried out on the shale gas reservoir after the well type solution is well designed. The principle of the directional blasting design is to maximize an oil drainage area, but also requires long-term stable production to be suitable for further transformation at the late stage. The directional blasting design specifically includes: quantity and positions of the branch holes to be blasted, construction flow, blasting direction, specific type of explosive, amount of explosive used in each branch hole, blasting method and the like.
The assembly of a coiled tubing and downhole pipeline robot system is finished.
After the mode and type of a coiled tubing operation vehicle (or skid-mounted, platform) is selected, the corresponding downhole pipeline robot, the assorted drilling tool 7, the assorted fast-curing liquid explosive thin-walled housing 10 and a spraying tool are selected, designed and assembled.
The coiled tubing 3 is an electrohydraulic composite tubing which supplies electric power to the drilling robot A 61 and supplies a drilling fluid circulating channel for drilling the fishbone multi-branch holes.
S2: drilling of the fishbone multi-branch holes: setting a coiled tubing and drilling robot system that carries a drilling tool 7 into a horizontal section of the horizontal hole 2 where drilling is completed in advance, and drilling a plurality of fishbone multi-branch holes through the coiled tubing and the drilling robot A
61according to the design; the step S2 specifically includes the following substeps:
S(1) setting a deflecting tool and finishing anchoring: setting the deflecting tool into a drilled long shale gas horizontal hole 2 by the matching of the coiled tubing 3 and the drilling robot A 61, and finishing anchoring of the deflecting tool by a hydraulic or mechanical way.
S(2) lifting a pipe string and replacing the drilling tool 7: lifting the pipe string of the coiled tubing robot, installing the drilling tool 7 and other tool equipment required for drilling the fishbone branch holes 5, and preparing to set into a wellhole for window sidetrack drilling.
S(3) setting the pipe string and performing window sidetrack drilling:
carrying the dynamic drilling tool 7 by the matching of the coiled tubing and the drilled robot A 61 to perform window sidetrack drilling. Because this method is also suitable for production enhancement and development of deep compact shale gas reservoirs, the drilling pressure required in the process of window sidetrack drilling in a deep well is relatively large. When the drilling pressure applied by the coiled tubing 3 is insufficient, the robot also has a certain tractive orientation capability, and relatively large drilling pressure can be generated by combining the coiled tubing with the robot, so that the fishbone branch holes 7 can be drilled rapidly and efficiently as designed.
S3. well cementation of the fishbone multi-branch hole 5: drawing out the coiled tubing 3 and drilling robot A 61 that carries the drilling tool 7, then replacing the drilling tool 7 with a well cementation tool and a bushing, and later setting the well cementation tool and the bushing to the bottom of the fishbone branch hole 5 to finish well cementation, or performing well completion directly with naked eyes; the step S3 specifically includes the following substeps (the following substeps are unnecessary for well cementation with naked eyes):
S(1) drawing out the original pipe string and replacing the well cementation tool:
lifting the coiled tubing 3 to the wellhead, installing a corresponding bushing setting tool according to design requirements and then setting to the bottom of the fishbone branch hole 5.
S(2) setting a tail pipe and displacing fluid: setting the well-completion pipe strong basically the same as the conventional operation of setting the tail pipe, which should follow the principles "not fast, not stop", stopping grouting after the pipe string enters the horizontal section, and continuously setting the pipe string.
S(3) injecting cement for well cementation after the tail pipe reaches a predetermined position: setting the tail pipe to reach the bottom of the fishbone branch hole 5, beginning to inject cement after the bushing of the fishbone branch hole 5 is centralized and then successfully hung to a bushing of the primary well, stopping injecting after reaching a designed return top, and waiting for solidification.
S(4) completing well cementation of the fishbone branch hole 5, drawing out the tool and preparing for next operation; finally, repeating S3 and S4 as designed to drill a plurality of asymmetric (or symmetric) multi-branch fishbone horizontal holes 2 which are located on opposite sides (or the same side) and have certain well depths and certain branched angles, finishing well cementation of TAML4 level, and making preparation works for production enhancement by blast-fracturing at the late stage.
S4. blasting preparation by spraying explosive to the bottom of the fishbone branch hole: installing the fast-curing liquid explosive thin-walled housingon the coiled tubing 3 and the drilling robot C 63, setting the coiled tubing 3 and the drilling robot C 63 to the bottom of the fishbone branch hole, spraying fast-curing explosive through the coiled tubing 3 and drilling robot C 63 and preparing blasting;
the step S4 specifically includes the following substeps:
S(1) lifting the pipe string and replacing the tool: lifting the coiled tubing system, and replacing the drilling and completion tool carried by the robot originally with a fast-curing liquid explosive thin-walled housing 10 and a spraying device.
S(2) setting the pipe string and placing explosive in a right place: feeding the explosive tube cavity to the bottom of the fishbone branch hole 5 under the actions of the thrust of the coiled tubing 3 and the traction force of the drilling robot C 63, and preparing to pressurize and spray the fast-curing liquid explosive.
S(3) pressurizing and spraying, and separating the robot from the explosive tube cavity: pumping liquid by ground coiled tubing operation supporting equipment to pressurize, wherein after reaching a rated pressure, the liquid explosive in the explosive thin-walled housing 10 is sprayed to the bottom of the fishbone branch hole 5 through the nozzle 11 at the front end of the tube cavity and then fast cured to the surface of the bushing on the wall of the well; separating the robot C 63 from the explosive tube cavity, reserving the explosive and the detonating device at the bottom of the fishbone branch hole 5, drawing out the coiled tubing and robot fishbone branch hole 5 to be blasted as designed, starting a ground detonating pipeline to detonate the fishbone multi-branch holes, and preparing for gas testing for putting into production after blasting is finished.
In Step S4. when shale near each fishbone multi-branch hole is blasted at high temperature and high pressure within a very short time, a large amount of self-supporting micro-fractures are finally generated under the combined action of exploded mechanical (rock breaking and fracture expanding) action, a thermal action (a contaminated zone near well is released), a chemical action (acid gas generated by blasting etches the shale formation), a stress wave action (which makes rock deformed and damaged to realize ultrasonic oil exploitation) and the like to form a complex fracture network system, so that the farther shale reservoir which is difficult to use is communicated, the gas drainage area is greatly increased, the use level of the formation reserves is improved, the oil and gas yield is increased, the development cost is saved, and finally the purpose of low-cost and effective development of low-permeability oil and gas reservoirs is achieved.
On the other hand, in the deep compact shale gas reservoir which is difficult to realize effective production enhancement by original hydraulic fracturing, the transformation effect of high temperature and high pressure generated by blasting of the liquid explosive is far superior to the transformation by hydraulic fracturing.
However, in terms of equipment, a large-volume high-power fracturing vehicle set is unnecessary for this method, only the coiled tubing operation vehicle and assorted tools thereof are used, and therefore the using cost of the equipment is greatly reduced, the single-well production enhancement cost is greatly compressed, and the single-well yield is also greatly improved.
In step S4, in order to achieve an expected production enhancement effect, the fast-curing explosive needs to be sprayed along the design direction. Like perforation, the difference of the blasting direction also will cause different production enhancement effects. In addition, the use amount of explosive should reach a design value, but is not excessive to avoid the damage to other fishbone branch holes 5 or the primary horizontal hole 2.
S5. production enhancement by blasting: drawing out the coiled tubing 3 and other auxiliary tools first, then detonating the explosive on the bottom to fracture rock of the shale gas reservoir, such that more shale gas stored in shale may be gathered to the wellhole to realize low-cost, high-efficiency, safe and environmentally-friendly production of the shale gas; and S6. stable production at the late stage.
In the late stage of production enhancement and development, the productivity declines gradually with shale gas in the gas reservoir upon the communication of the fractures generated by original blasting being produced, such that a shale gas well may realize high-efficiency and sustainable stable production, and the transformed shale gas reservoir may be subjected to secondary transformation. The sustainable stable production is also the key for making the measure for production enhancement effective.
First, the secondary solution for production enhancement needs to be designed.
It is necessary to combine the development history and effect of this block of this well and consider the geological knowledge understood more deeply during production in many years at the early stage, and it is also necessary to make the fishbone branch holes 5 that are well drilled and not subjected to blast-fracturing to communicate an oil and gas reservoir of a relatively large scale as much as possible. Upon calculation design, the natural fractures, fractures generated in production enhancement by blasting at the early stage and the blasting fractures in this design form a fracture network, so that the transformation volume is further increased, and the yield and the final recovery rate are improved.
The stable production and construction solutions at the late stage in the three solutions A, B and C are described as follows:
Solution A: transforming original drilled fishbone branch holes 5 by applying the construction method in the step S5.
In the solution A, the coiled tubing and drilling robot enters the fishbone branch hole 5 which is drilled first by using this method and is not subject to blast-fracturing according to a first development and transformation design, and if all the first fishbone branch holes 5 undergo a production enhancement and transformation operation by liquid explosive blasting, stable production and transformation needs to be finished by other measures.
Solution B: continuing to adopt steps S3, S4 and S5 cyclically to drill the fishbone branch holes 5 as designed, carrying out well cementation according to a TAML4 level or direct well cementation with naked eyes, and conveying the explosive tube cavity to the bottom of the fishbone branch hole 5 by the matching of the coiled tubing 3 and the drilling robot 6 and carrying out production enhancement by blasting.
The horizontal hole 2 is required to be longer in Solution B, and the fishbone branch holes 5 may be uniformly distributed around the primary hole, such that the fishbone branch holes 5 may contact the formation of the shale gas reservoir better, and the reentrant ability to the primary wellhole is high. The underground situations should be sufficiently argued before the stable production operation at the late stage in this solution to guard against various downhole accidents.
Solution C: the fracture network after first production enhancement by blasting has good connectivity and high flow conductivity, and the fast-curing liquid explosive may also be pumped to fractures generated in first transformation by the coiled tubing 3 by a way of hydraulic fracturing construction when stable production maintenance measures at the late stage are adopted, and is then detonated.
In Solution C, the original fracture network is required to have high permeability, and the fast-curing liquid explosive can flow to the formation better, and more fractures can be generated after blasting, thereby communicating the shale gas reservoir to the greater extent.
Owing to complex formation situations, poor cementability of formation at branched points and frequent downhole accidents of shale gas reservoirs of China, mechanical support and hydraulic packing must be considered when a well cementation mode of the fishbone branch holes 5 is selected, and therefore, a well cementation process of TAML4 level is adopted. That is, well cementation of both the primary hole and the branch hole is completed. The mechanical support is provided at cementation process of TAML4 level is adopted. That is, well cementation of both the primary hole and the branch hole is completed. The mechanical support is provided at the connection between every two branched points. In consideration of the needs of the operations at the late stage, such as production enhancement by directional blast-fracturing, two wellholes have the selective reentrant ability. Or well completion is directly performed with naked eyes in a section where the formation situations are simple and the well wall stability is good. A deflecting tool is set to a design position by the coiled tubing 3 and is anchored before window sidetrack drilling for the multi-branch fishbone horizontal holes 2 in the step S2. In the S4, the thin-walled housing filled with the fast-curing liquid explosive is fed to the bottom of the fishbone branch hole 5 by the matching of the coiled tubing 3 and the drilling robot C 6. In the step S4, liquid pumped through the coiled tubing 3 is pressurized to a predetermined value, such that explosive in the explosive thin-walled housingis sprayed to the bottom of the fishbone branch hole 5 through the front end of the explosive tube cavity.
In the step S5, the ground detonating device sends a detonating signal to the detonating device on the explosive tube cavity to realize detonating and fracture rock to form a fracture network, thereby achieving the purpose of low-cost production enhancement and development of shale gas.
As shown in Figure 2, the system for drilling the multi-branch fishbone horizontal holes by the matching of the coiled tubing 3 and the drilling robot A 61 is used for drilling fishbone multilevel branched horizontal holes of the shale gas reservoir so as to provide a foundation for subsequent well-completion and production enhancement through blast-fracturing transformation and consists of coiled tubing 3, a drilling robot A 61 and a drilling tool 7, wherein the drilling tool 7 is provided at the front end of the drilling robot A 61 and consists of a centralizer, a drilling jar and a drilling bit which are sequentially connected;
As shown in Figure 3, the well-completion system for microholes of the branch hole by the matching of the coiled tubing 3 and the drilling robot A 62 is used for carrying out well-completion construction on the fishbone multilevel branched horizontal holes where drilling is completed to make preparations for high-efficiency, safe and low-cost production enhancement by blasting fracturing transformation, and consists of coiled tubing 3, a drilling robot B 62 and a well-completion tool, wherein the well-completion tool is provided at the front end of the drilling robot B
62 and comprising a float shoe, a float collar, a magnetic locator suband a centralizer which are sequentially connected within a bushing 4;
As shown in Figure 4, the system for blasting and transforming the multi-branch fishbone horizontal holes consists of coiled tubing 3, a drilling robot C 63 and a multifunctional fast-curing liquid explosive thin-walled housing 10, wherein an explosive tube cavity of the multifunctional fast-curing liquid explosive thin-walled housing 10 is filled with a fast-curing liquid explosive; a piston cylinder 12 is provided between the front end of the drilling robot C 63 and the tail of the multifunctional fast-curing liquid explosive thin-walled housing10; a nozzle 11 of the explosive tube cavity can be opened by means of means of the hydraulic pressure provided by the piston cylinder 12 under the thrust of the liquid, such that the explosive is sprayed out; a connector which can be separated under the control of electric power and hydraulic pressure is provided between the tail of the explosive tube cavity and the front end of the drilling robot C 63; after the drilling robot C 63 sprays the fast-curing liquid explosive completely, the connector is powered off, such that the multifunctional fast-curing liquid explosive thin-walled housing 10 is reserved at the bottom of the branched fishbone well 5; the drilling robot C
63 is drawn out along with the coiled tube 3; and a one-way valve is provided in front of the explosive tube cavity. A detonating device is provided at the upper part of the explosive tube cavity. The detonating device is connected with ground control equipment through a detonating line on the detonating device.
The drilling robot A 61, the drilling robot B 62 and the drilling robot C 63 are identical in structure. Each drilling robot is equipped with an active driving device for driving the drilling robot to move autonomously, wherein the active driving device can realize a self-driving function under the electric power provided by the coiled tubing 3, and can be set down by matching with the coiled tubing 3 to provide the drilling pressure in a deep well section where the coiled tubing 3 cannot provide sufficient setting force. Each drilling robot is internally provided with a passageway for pump injection of liquid during drilling and completion, blasting transformation and stable production at the late stage. One end of the coiled tube 3 is connected with ground support equipment, and the other end of the coiled tube 3 is communicated =
with the passageway. A piston is provided in the passageway and separates the passageway of the robot apart from the explosive tube cavity.
The drilling tool 7 of the drilling robot is equipped with multiple sensors which are used for monitoring downhole conditions, downhole positioning and downhole operations. The drilling robot has relatively high anti-sliding and waterproof operation capability under extreme environments, and specially can operate reliably in a wellhole filled with drilling fluid. The drilling robot has an oriented walking mechanism which ensures that the drilling robot can accurately walk to a specific position in the fishbone multi-branch wellhole.
An adaptive joint is provided at the front end and the rear end of each of the drilling robots respectively, wherein one adaptive joint is connected with an electrohydraulic channel of the coiled tubing 3, and the other one is connected with the multifunctional fast-curing liquid explosive thin-walled housing 10 through the drilling tool 7 and the well-completion tool.
The detonating device must satisfy the following requirements: the fast-curing liquid explosive is safe and easy to transport, and is safe, reliable, easy to control and large in blasting energy in extremely severe environments of high temperature and high pressure in a deep well; the fast-curing liquid explosive has good flowability in a liquid state and small friction to a manifold and is convenient to spray; the fast-curing liquid explosive can be fast attached and cured after being sprayed to rack;
and the explosive has good compatibility with a detonating pipeline, and the detonating pipeline is easy to install, unlikely to be damaged and suitable for long-distance detonation in a deep well.
The multi-functional fast-curing liquid explosive thin-walled housing 10 must satisfy the followings: the thin-walled housing has better compatibility with the downhole drilling robots and the coiled tubing; the thin-walled housing is cylindrical and hollow integrally, and is used for storing explosive, and six fin-shaped metal ribs are disposed outside the housing and used for protecting the housing body from being abraded, scraped and damaged by the wellhole wall in the process of moving underground; the housing can withstand relatively large pressure and relatively high temperature by means of its material, and can work reliably in a deep well over 4000 metres; the wall of the housing is thin, high in strength and unlikely to be damaged;
the tail of the thin-walled housingis connected with the liquid passageway in the drilling robot C; the piston is arranged in the front of the passageway at the tail to separate the passageway of the drilling robot C apart from the explosive cavity, and has good sealability after the explosive is charged, thus ensuring that liquid from the coiled tubing cannot flow into the explosive tube cavity; the piston can slidably extrude the liquid explosive in the explosive tube cavity under a certain liquid pressure to achieve the purpose that the liquid explosive is sprayed out by extruding;
and the thin-walled housing has a multifunctional special nozzle which is large in spraying area, is capable of freely rotating in the spraying process and is anti-clogging.
The drilling tool 7 must satisfy the followings: the drilling tool 7 has favorable compatibility with the coiled tubing and the drilling robots, and adopts an electrically-driven or hydraulically-driven drill bit; a deflecting tool can be mounted conveniently, such that qualified fishbone multi-branch holes may be drilled accurately according to design angles; the drill bit has good wear resistance and high mechanism reliability and can satisfy one-time drilling of all or multiple designed fishbone multi-branch holes; the centralizer ensures smooth drilling to a target in a vertical well section without deflecting; and a cuttings and drilling fluid return passageway is reserved in a shell of the drilling tool, thereby ensuring that chippings can be carried to the ground rapidly and smoothly.
The coiled tubing 3 must satisfy the followings: the coiled tubing is an electrohydraulic composite tubing which can supply necessary driving power, liquid energy, electric power and substances for a downhole system; the coiled tubing has the normal working hole depth which should reach over 4000 metres, and is unlikely to failure due to fatigue wear and suitable for multiple downhole operations;
and the coiled tubing has good compatibility with other downhole tools, and can be matched with the drilling robots reliably so as to supply electric power and liquid energy for the drilling robots.
The drilling robot A 61 in the system for drilling the multi-branch fishbone horizontal holes by the matching of the coiled tubing and the drilling robot must satisfy the followings: the coiled tubing may be connected with the drilling robot A 61 so as to supply liquid energy and electric power to the coiled tubing; the drilling robot A 61 has an oriented walking mechanism which ensures that the drilling robot can accurately walk to a specific position in the fishbone multi-branch wellhole;
the drilling robot A 61 can carry various sensors which are matched with the drilling tool and used for monitoring downhole conditions, positioning, downhole operations and the like; the drilling robot A 61 has relatively strong traction ability and can be matched with the coiled tubing to provide a drilling pressure for the drilling tool so as to realize the purpose of drilling to a target section efficiently and safely;
the drilling robot A 61 has relatively high anti-sliding and waterproof operation capabilities under extreme downhole environments, and especially in a wellhole filled with drilling fluid;
and the drilling robot A 61 is cylindrical and reserved with a liquid passageway, wherein the tail of the drilling robot A 61 is connected with the coiled tubing and the head of the drilling robot A 61 is connected with the corresponding drilling tool.
The drilling robot C 61 in the system for blasting and transforming the multi-branch fishbone horizontal holes must satisfy the followings: the front end of the drilling robot C 61 is connected with the piston cylinder at the tail of the multifunctional fast-curing liquid explosive thin-walled housing and provides hydraulic energy therefor, such that the nozzle at the front end of the explosive tube cavity can be opened under the action of the liquid thrust as designed, and then the explosive in the tube cavity is sprayed out; the conjunction between the front end of the drilling robot and the tail of the explosive tube cavity may be out of connection under the control of electric power or hydraulic pressure, such that the drilling robot retains the thin-walled housing at the bottom of the branch hole after the fast-curing liquid explosive is sprayed out, and then the drilling robot may be drawn out along with the coiled tubing.
Furthermore, blasting and production enhancement operations can be finished efficiently and safely in the system for blasting and transforming the multi-branch fishbone horizontal holes. Equipment and pipelines for the detonating system, and the type selection and design quantity of the fast-curing liquid explosive also must satisfy the corresponding requirements as follows: the fast-curing liquid explosive is safe and easy to transport, and is safe, reliable, easy to control and large in blasting energy in extremely severe environments of high temperature and high pressure in a deep well:
the fast-curing liquid explosive has good flowability in a liquid state and small friction to a manifold and is convenient to spray; the fast-curing liquid explosive can be fast attached and cured after being sprayed to rack; and the explosive has good compatibility with a detonating pipeline, and the detonating pipeline is easy to install, unlikely to be damaged and suitable for long-distance detonation in a deep well.
A drilling and completion and production enhancement method using a drilling robot for drilling multi-branch fishbone radial microholes in a shale gas reservoir comprises the following steps: SI-S6:
S1 . design of an overall solution: designing an overall well body structure, a drilling solution, a well-completion solution and production enhancement through blast-fracturing of each multi-branch fishbone horizontal hole; and this step mainly includes designs of a drilling and completion solution and a solution of production enhancement by blasting, and device installation and pipeline layout of the coiled tubing 3 on the wellhead. Furthermore, the step Si also make preparations for next constructions, i.e., solution formulation, dispatching of equipment to the site, assembly of coiled tubing operation system, installation of an assorted wellhead device, installation of the drilling tool on the coiled tube and drilling robot A 61, before production enhancement, development and construction of shale gas.
It is necessary to consider the size and morphology of the shale gas reservoir and sufficiently cognize the geology in terms of the solution design, so that the branch hole can communicate an oil and gas reservoir of a relatively large scale as much as possible to facilitate next development of blast-fracturing. First, the well type design includes: quantity design of fishbone branch holes 5, symmetric and asymmetric arrangement, a distance between every two adjacent branches, included angles between branch holes and the primary well, well depth of each fishbone branch hole 5 and the like, all of which should be made by sufficiently arguing the liberation degree of the designed well type to the productivity through combining geological knowledge and using computer engineering simulation.
A directional blasting design is carried out on the shale gas reservoir after the well type solution is well designed. The principle of the directional blasting design is to maximize an oil drainage area, but also requires long-term stable production to be suitable for further transformation at the late stage. The directional blasting design specifically includes: quantity and positions of the branch holes to be blasted, construction flow, blasting direction, specific type of explosive, amount of explosive used in each branch hole, blasting method and the like.
The assembly of a coiled tubing and downhole pipeline robot system is finished.
After the mode and type of a coiled tubing operation vehicle (or skid-mounted, platform) is selected, the corresponding downhole pipeline robot, the assorted drilling tool 7, the assorted fast-curing liquid explosive thin-walled housing 10 and a spraying tool are selected, designed and assembled.
The coiled tubing 3 is an electrohydraulic composite tubing which supplies electric power to the drilling robot A 61 and supplies a drilling fluid circulating channel for drilling the fishbone multi-branch holes.
S2: drilling of the fishbone multi-branch holes: setting a coiled tubing and drilling robot system that carries a drilling tool 7 into a horizontal section of the horizontal hole 2 where drilling is completed in advance, and drilling a plurality of fishbone multi-branch holes through the coiled tubing and the drilling robot A
61according to the design; the step S2 specifically includes the following substeps:
S(1) setting a deflecting tool and finishing anchoring: setting the deflecting tool into a drilled long shale gas horizontal hole 2 by the matching of the coiled tubing 3 and the drilling robot A 61, and finishing anchoring of the deflecting tool by a hydraulic or mechanical way.
S(2) lifting a pipe string and replacing the drilling tool 7: lifting the pipe string of the coiled tubing robot, installing the drilling tool 7 and other tool equipment required for drilling the fishbone branch holes 5, and preparing to set into a wellhole for window sidetrack drilling.
S(3) setting the pipe string and performing window sidetrack drilling:
carrying the dynamic drilling tool 7 by the matching of the coiled tubing and the drilled robot A 61 to perform window sidetrack drilling. Because this method is also suitable for production enhancement and development of deep compact shale gas reservoirs, the drilling pressure required in the process of window sidetrack drilling in a deep well is relatively large. When the drilling pressure applied by the coiled tubing 3 is insufficient, the robot also has a certain tractive orientation capability, and relatively large drilling pressure can be generated by combining the coiled tubing with the robot, so that the fishbone branch holes 7 can be drilled rapidly and efficiently as designed.
S3. well cementation of the fishbone multi-branch hole 5: drawing out the coiled tubing 3 and drilling robot A 61 that carries the drilling tool 7, then replacing the drilling tool 7 with a well cementation tool and a bushing, and later setting the well cementation tool and the bushing to the bottom of the fishbone branch hole 5 to finish well cementation, or performing well completion directly with naked eyes; the step S3 specifically includes the following substeps (the following substeps are unnecessary for well cementation with naked eyes):
S(1) drawing out the original pipe string and replacing the well cementation tool:
lifting the coiled tubing 3 to the wellhead, installing a corresponding bushing setting tool according to design requirements and then setting to the bottom of the fishbone branch hole 5.
S(2) setting a tail pipe and displacing fluid: setting the well-completion pipe strong basically the same as the conventional operation of setting the tail pipe, which should follow the principles "not fast, not stop", stopping grouting after the pipe string enters the horizontal section, and continuously setting the pipe string.
S(3) injecting cement for well cementation after the tail pipe reaches a predetermined position: setting the tail pipe to reach the bottom of the fishbone branch hole 5, beginning to inject cement after the bushing of the fishbone branch hole 5 is centralized and then successfully hung to a bushing of the primary well, stopping injecting after reaching a designed return top, and waiting for solidification.
S(4) completing well cementation of the fishbone branch hole 5, drawing out the tool and preparing for next operation; finally, repeating S3 and S4 as designed to drill a plurality of asymmetric (or symmetric) multi-branch fishbone horizontal holes 2 which are located on opposite sides (or the same side) and have certain well depths and certain branched angles, finishing well cementation of TAML4 level, and making preparation works for production enhancement by blast-fracturing at the late stage.
S4. blasting preparation by spraying explosive to the bottom of the fishbone branch hole: installing the fast-curing liquid explosive thin-walled housingon the coiled tubing 3 and the drilling robot C 63, setting the coiled tubing 3 and the drilling robot C 63 to the bottom of the fishbone branch hole, spraying fast-curing explosive through the coiled tubing 3 and drilling robot C 63 and preparing blasting;
the step S4 specifically includes the following substeps:
S(1) lifting the pipe string and replacing the tool: lifting the coiled tubing system, and replacing the drilling and completion tool carried by the robot originally with a fast-curing liquid explosive thin-walled housing 10 and a spraying device.
S(2) setting the pipe string and placing explosive in a right place: feeding the explosive tube cavity to the bottom of the fishbone branch hole 5 under the actions of the thrust of the coiled tubing 3 and the traction force of the drilling robot C 63, and preparing to pressurize and spray the fast-curing liquid explosive.
S(3) pressurizing and spraying, and separating the robot from the explosive tube cavity: pumping liquid by ground coiled tubing operation supporting equipment to pressurize, wherein after reaching a rated pressure, the liquid explosive in the explosive thin-walled housing 10 is sprayed to the bottom of the fishbone branch hole 5 through the nozzle 11 at the front end of the tube cavity and then fast cured to the surface of the bushing on the wall of the well; separating the robot C 63 from the explosive tube cavity, reserving the explosive and the detonating device at the bottom of the fishbone branch hole 5, drawing out the coiled tubing and robot fishbone branch hole 5 to be blasted as designed, starting a ground detonating pipeline to detonate the fishbone multi-branch holes, and preparing for gas testing for putting into production after blasting is finished.
In Step S4. when shale near each fishbone multi-branch hole is blasted at high temperature and high pressure within a very short time, a large amount of self-supporting micro-fractures are finally generated under the combined action of exploded mechanical (rock breaking and fracture expanding) action, a thermal action (a contaminated zone near well is released), a chemical action (acid gas generated by blasting etches the shale formation), a stress wave action (which makes rock deformed and damaged to realize ultrasonic oil exploitation) and the like to form a complex fracture network system, so that the farther shale reservoir which is difficult to use is communicated, the gas drainage area is greatly increased, the use level of the formation reserves is improved, the oil and gas yield is increased, the development cost is saved, and finally the purpose of low-cost and effective development of low-permeability oil and gas reservoirs is achieved.
On the other hand, in the deep compact shale gas reservoir which is difficult to realize effective production enhancement by original hydraulic fracturing, the transformation effect of high temperature and high pressure generated by blasting of the liquid explosive is far superior to the transformation by hydraulic fracturing.
However, in terms of equipment, a large-volume high-power fracturing vehicle set is unnecessary for this method, only the coiled tubing operation vehicle and assorted tools thereof are used, and therefore the using cost of the equipment is greatly reduced, the single-well production enhancement cost is greatly compressed, and the single-well yield is also greatly improved.
In step S4, in order to achieve an expected production enhancement effect, the fast-curing explosive needs to be sprayed along the design direction. Like perforation, the difference of the blasting direction also will cause different production enhancement effects. In addition, the use amount of explosive should reach a design value, but is not excessive to avoid the damage to other fishbone branch holes 5 or the primary horizontal hole 2.
S5. production enhancement by blasting: drawing out the coiled tubing 3 and other auxiliary tools first, then detonating the explosive on the bottom to fracture rock of the shale gas reservoir, such that more shale gas stored in shale may be gathered to the wellhole to realize low-cost, high-efficiency, safe and environmentally-friendly production of the shale gas; and S6. stable production at the late stage.
In the late stage of production enhancement and development, the productivity declines gradually with shale gas in the gas reservoir upon the communication of the fractures generated by original blasting being produced, such that a shale gas well may realize high-efficiency and sustainable stable production, and the transformed shale gas reservoir may be subjected to secondary transformation. The sustainable stable production is also the key for making the measure for production enhancement effective.
First, the secondary solution for production enhancement needs to be designed.
It is necessary to combine the development history and effect of this block of this well and consider the geological knowledge understood more deeply during production in many years at the early stage, and it is also necessary to make the fishbone branch holes 5 that are well drilled and not subjected to blast-fracturing to communicate an oil and gas reservoir of a relatively large scale as much as possible. Upon calculation design, the natural fractures, fractures generated in production enhancement by blasting at the early stage and the blasting fractures in this design form a fracture network, so that the transformation volume is further increased, and the yield and the final recovery rate are improved.
The stable production and construction solutions at the late stage in the three solutions A, B and C are described as follows:
Solution A: transforming original drilled fishbone branch holes 5 by applying the construction method in the step S5.
In the solution A, the coiled tubing and drilling robot enters the fishbone branch hole 5 which is drilled first by using this method and is not subject to blast-fracturing according to a first development and transformation design, and if all the first fishbone branch holes 5 undergo a production enhancement and transformation operation by liquid explosive blasting, stable production and transformation needs to be finished by other measures.
Solution B: continuing to adopt steps S3, S4 and S5 cyclically to drill the fishbone branch holes 5 as designed, carrying out well cementation according to a TAML4 level or direct well cementation with naked eyes, and conveying the explosive tube cavity to the bottom of the fishbone branch hole 5 by the matching of the coiled tubing 3 and the drilling robot 6 and carrying out production enhancement by blasting.
The horizontal hole 2 is required to be longer in Solution B, and the fishbone branch holes 5 may be uniformly distributed around the primary hole, such that the fishbone branch holes 5 may contact the formation of the shale gas reservoir better, and the reentrant ability to the primary wellhole is high. The underground situations should be sufficiently argued before the stable production operation at the late stage in this solution to guard against various downhole accidents.
Solution C: the fracture network after first production enhancement by blasting has good connectivity and high flow conductivity, and the fast-curing liquid explosive may also be pumped to fractures generated in first transformation by the coiled tubing 3 by a way of hydraulic fracturing construction when stable production maintenance measures at the late stage are adopted, and is then detonated.
In Solution C, the original fracture network is required to have high permeability, and the fast-curing liquid explosive can flow to the formation better, and more fractures can be generated after blasting, thereby communicating the shale gas reservoir to the greater extent.
Owing to complex formation situations, poor cementability of formation at branched points and frequent downhole accidents of shale gas reservoirs of China, mechanical support and hydraulic packing must be considered when a well cementation mode of the fishbone branch holes 5 is selected, and therefore, a well cementation process of TAML4 level is adopted. That is, well cementation of both the primary hole and the branch hole is completed. The mechanical support is provided at cementation process of TAML4 level is adopted. That is, well cementation of both the primary hole and the branch hole is completed. The mechanical support is provided at the connection between every two branched points. In consideration of the needs of the operations at the late stage, such as production enhancement by directional blast-fracturing, two wellholes have the selective reentrant ability. Or well completion is directly performed with naked eyes in a section where the formation situations are simple and the well wall stability is good. A deflecting tool is set to a design position by the coiled tubing 3 and is anchored before window sidetrack drilling for the multi-branch fishbone horizontal holes 2 in the step S2. In the S4, the thin-walled housing filled with the fast-curing liquid explosive is fed to the bottom of the fishbone branch hole 5 by the matching of the coiled tubing 3 and the drilling robot C 6. In the step S4, liquid pumped through the coiled tubing 3 is pressurized to a predetermined value, such that explosive in the explosive thin-walled housingis sprayed to the bottom of the fishbone branch hole 5 through the front end of the explosive tube cavity.
In the step S5, the ground detonating device sends a detonating signal to the detonating device on the explosive tube cavity to realize detonating and fracture rock to form a fracture network, thereby achieving the purpose of low-cost production enhancement and development of shale gas.
Claims (7)
1. A drilling, completion and production enhancement system for use in a shale gas reservoir, the system comprising a coiled tubing;
a drilling system to drill a fishbone-shaped multi-branch horizontal well, the drilling system comprising a drilling robot A and a drilling tool, wherein the drilling tool is provided at a front end of the drilling robot A and comprises a first centralizer, a jar and a drill bit which are sequentially connected, and the coiled tubing is connected to the drilling robot A at a rear end of the drilling robot A and cooperates with the drilling robot A to drill the fishbone-shaped multi-branch horizontal well by the use of the drilling tool;
a slim hole completion system for use in the fishbone-shaped multi-branch horizontal well, the slim hole completion system comprising a drilling robot B and a well completion tool, wherein the well completion tool is provided at a front end of the drilling robot B and comprises a float shoe, a float collar, a magnetic locater sub, and a second centralizer which arc sequentially connected within a bushing, and the coiled tubing is connected to the drilling robot B at a rear end of the drilling robot B and cooperates with the drilling robot B to complete the fishbone-shaped multi-branch horizontal well by the use of the well completion tool; and a blasting reconstruction system for use in the fishbone-shaped multi-branch horizontal well completed by the slim hole completion system, the blasting reconstruction system comprising a drilling robot C being connected to the coiled tubing at a rear end of the drilling robot C;
a multifunctional thin-walled housing having an explosive tube cavity to be filled with a fast curing liquid explosive, the explosive tube cavity comprising a spray nozzle at its head, a one-way valve and a detonator;
a piston cylinder which is provided between a front end of the drilling robot C and a tail of the multifunctional thin-walled housing and provides a hydraulic pressure to force the liquid explosive within the explosive tube cavity to open the spray nozzle thus allowing the spraying of the liquid explosive; and a connector separable under an electric control which is provided between a tail of the explosive tube cavity and the drilling robot C, wherein the connector is powered off upon the completion of the spraying of the liquid explosive to retain the multifunctional thin-walled housing at a bottom of the fishbone-shaped multi-branch well, and the drilling robot C is detached from the multifunctional thin-walled housing and is pulled out of the fishbone-shaped multi-branch well together with the coiled tubing.
a drilling system to drill a fishbone-shaped multi-branch horizontal well, the drilling system comprising a drilling robot A and a drilling tool, wherein the drilling tool is provided at a front end of the drilling robot A and comprises a first centralizer, a jar and a drill bit which are sequentially connected, and the coiled tubing is connected to the drilling robot A at a rear end of the drilling robot A and cooperates with the drilling robot A to drill the fishbone-shaped multi-branch horizontal well by the use of the drilling tool;
a slim hole completion system for use in the fishbone-shaped multi-branch horizontal well, the slim hole completion system comprising a drilling robot B and a well completion tool, wherein the well completion tool is provided at a front end of the drilling robot B and comprises a float shoe, a float collar, a magnetic locater sub, and a second centralizer which arc sequentially connected within a bushing, and the coiled tubing is connected to the drilling robot B at a rear end of the drilling robot B and cooperates with the drilling robot B to complete the fishbone-shaped multi-branch horizontal well by the use of the well completion tool; and a blasting reconstruction system for use in the fishbone-shaped multi-branch horizontal well completed by the slim hole completion system, the blasting reconstruction system comprising a drilling robot C being connected to the coiled tubing at a rear end of the drilling robot C;
a multifunctional thin-walled housing having an explosive tube cavity to be filled with a fast curing liquid explosive, the explosive tube cavity comprising a spray nozzle at its head, a one-way valve and a detonator;
a piston cylinder which is provided between a front end of the drilling robot C and a tail of the multifunctional thin-walled housing and provides a hydraulic pressure to force the liquid explosive within the explosive tube cavity to open the spray nozzle thus allowing the spraying of the liquid explosive; and a connector separable under an electric control which is provided between a tail of the explosive tube cavity and the drilling robot C, wherein the connector is powered off upon the completion of the spraying of the liquid explosive to retain the multifunctional thin-walled housing at a bottom of the fishbone-shaped multi-branch well, and the drilling robot C is detached from the multifunctional thin-walled housing and is pulled out of the fishbone-shaped multi-branch well together with the coiled tubing.
2. The drilling, completion and production enhancement system according to claim 1, wherein the well drilling robot A, the well drilling robot B and the well drilling robot C are identical in structure, each of which is provided with a driving device for driving the well drilling robot to move autonomously; the well drilling robot A is provided with a channel therein for pumping of liquid during a well drilling stage, the well drilling robot B is provided with a channel therein for pumping of liquid during a well completion stage, and the well drilling robot C is provided with a channel therein for pumping of liquid during a blasting reconstruction and production stabilization stage; and wherein a first end of the coiled tubing is connected with ground support equipment, and a second end of the coiled tubing, being opposite to the first end of the coiled tubing, communicates with the channel of the well drilling robot A, the well drilling robot B or the well drilling robot C.
3. The drilling, completion and production enhancement system according to claim 1, wherein the drilling tool is provided with a plurality of sensors for monitoring downhole conditions. downhole positioning and downhole operations.
4. The drilling, completion and production enhancement system according to claim 1 or claim 2, wherein the front end and the rear end of each of the well drilling robot A, the well drilling robot B and the well drilling robot C are provided with an adapter respectively, wherein a first end of the adapter is connected with an electro-hydraulic passage of the coiled tubing, and a second end of the adapter, being opposite to the first end of the adapter, is connected with the drilling tool, the well completion tool or the multifunctional thin-walled housing.
5. The drilling, completion and production enhancement system according to claim 2, wherein the ground support equipment is a coiled tubing operation platform or a coiled tubing operation vehicle.
6. The drilling, completion and production enhancement system according to claim 2, wherein the detonator is connected with the ground control equipment through a detonating circuit on the detonator.
7. The drilling, completion and production enhancement system according to claim 1, wherein the slim hole completion system uses a well completion tool with a difficulty level of TAML4.
Applications Claiming Priority (5)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410665275.7A CN104533287B (en) | 2014-11-20 | 2014-11-20 | A kind of fish spicule shape multilevel branch horizontal well shale gas reservoir that bores is drilled well and stimulation system |
| CN201410665671.XA CN104533288B (en) | 2014-11-20 | 2014-11-20 | A kind of fish spicule shape multilevel branch horizontal well shale gas reservoir that bores is drilled the method that well is with increasing production |
| CN201410665671.X | 2014-11-20 | ||
| CN201410665275.7 | 2014-11-20 | ||
| PCT/CN2015/100360 WO2016078627A1 (en) | 2014-11-20 | 2015-12-31 | Production enhancement system using robot drill for drilling multi-branched fishbone and radial microholes in shale gas reservoir, and method therefor |
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| US10087736B1 (en) * | 2017-10-30 | 2018-10-02 | Saudi Arabian Oil Company | Multilateral well drilled with underbalanced coiled tubing and stimulated with exothermic reactants |
| CN110965979B (en) * | 2019-10-24 | 2021-11-26 | 中国石油大学(华东) | Deep combustion and explosion fracturing method in radial slim hole |
| CN111119789B (en) * | 2019-12-30 | 2022-04-01 | 河南工程学院 | Well completion method for coal bed gas ground L-shaped pre-pumping well with double-well-opening structure |
| CN113482556A (en) * | 2021-08-25 | 2021-10-08 | 成都理工大学 | Closed-loop well flushing method based on coiled tubing and telescopic robot |
| CN113756802B (en) * | 2021-09-28 | 2024-02-23 | 平安煤矿瓦斯治理国家工程研究中心有限责任公司 | Method for investigating fracturing drainage effect of coal bed gas horizontal well |
| CN115012893B (en) * | 2022-05-31 | 2024-04-16 | 贵州大学 | Ultrasonic wave cooperated hydraulic fracturing device for increasing yield of coalbed methane |
| CN115163041B (en) * | 2022-06-08 | 2023-06-16 | 中国地质大学（武汉） | Visual experimental simulation method for grouting and water plugging of horizontal branch well of coal seam floor |
| CN117722132A (en) * | 2023-11-23 | 2024-03-19 | 中能建数字科技集团有限公司 | Method for reforming depleted gas reservoir into compressed air gas reservoir and product |
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| CN100549358C (en) * | 2006-05-23 | 2009-10-14 | 辽河石油勘探局 | A kind of fish bone type branch well drilling and completing method |
| US7740069B2 (en) * | 2007-01-04 | 2010-06-22 | Michael Roy Young | Process for two-step fracturing of subsurface formations |
| US20090159286A1 (en) * | 2007-12-21 | 2009-06-25 | Schlumberger Technology Corporation | Method of treating subterranean reservoirs |
| CN101397888B (en) * | 2008-11-03 | 2011-12-14 | 中国石油集团长城钻探工程有限公司 | Fishbone-shaped branch well drilling and completion process |
| CN104533288B (en) * | 2014-11-20 | 2017-03-08 | 西南石油大学 | A kind of fish spicule shape multilevel branch horizontal well shale gas reservoir that bores is drilled the method that well is with increasing production |
| CN104533287B (en) * | 2014-11-20 | 2017-03-08 | 西南石油大学 | A kind of fish spicule shape multilevel branch horizontal well shale gas reservoir that bores is drilled well and stimulation system |
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