CN211950450U - A screen pipe cluster structure for hot dry rock fracturing - Google Patents
A screen pipe cluster structure for hot dry rock fracturing Download PDFInfo
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- CN211950450U CN211950450U CN202020214622.5U CN202020214622U CN211950450U CN 211950450 U CN211950450 U CN 211950450U CN 202020214622 U CN202020214622 U CN 202020214622U CN 211950450 U CN211950450 U CN 211950450U
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Abstract
A sieve tube string structure for hot dry rock fracturing comprises a top joint and a bottom joint, wherein a first sieve tube corresponding to a first layer section of a hot dry rock reservoir, a second sieve tube corresponding to a second layer section of the hot dry rock reservoir and a solid non-porous tube corresponding to a third layer section of the hot dry rock reservoir are arranged between the top joint and the bottom joint; selecting a fracturing layer according to a natural fracture development section displayed by a logging result; combining screen pipes with different parameters and solid pipes without holes and putting the screen pipes and the solid pipes into a well; simultaneously preparing clear water, acid liquor with certain concentration, slick water and a small amount of displacing liquid; firstly, injecting acid liquor by using a small displacement pump to remove near-well pollution and corrosion rocks, and then continuously injecting clear water by using the small displacement pump to ensure that reservoir rocks are thermally cracked; sequentially pumping clear water, slick water and acid liquor by adopting a step-up, constant and step-down displacement mode; pumping the displacing liquid to push the acid liquid into the stratum; and stopping the pump to release the pressure after the pump fills a certain amount of fracturing fluid, and circulating the steps.
Description
Technical Field
The utility model belongs to the technical field of hot dry rock development research, concretely relates to a screen pipe cluster structure for hot dry rock fracturing.
Background
The dry hot rock is a clean renewable energy source, the reserve of China is very huge, and according to preliminary estimation, the total amount of dry hot rock resources in the depth of 3-10 km in continental China is 2.5 multiplied by 1025J, about 860 trillion tons of standard coal, the reserves are in the forefront of the world. Even if the heat extraction efficiency of about 2 percent is considered, the amount of electricity converted from the heat energy in the huge reserves is considerable. Therefore, the development of the hot dry rock is of great significance to the adjustment of energy structure and energy safety in China. The development of hot dry rock requires the establishment of an Enhanced Geothermal System (EGS), the core of which is to drill a well into a reservoir and fracture the well to form a fracture network with a certain scale, and to construct a circulation loop of an injection well and a production well to extract heat energy for power generation.
Different from oil and gas reservoirs, the hot dry rock granite mass not only has the physical and mechanical properties of high temperature (more than or equal to 200 ℃), high hardness (HS 70), super-compactness (porosity of 0.3-0.7%) and obvious anisotropy (filling of various altered minerals), but also has the characteristics of large ground stress and large difference coefficient, and is difficult to perform fracturing construction. Therefore, there is a need for methods to overcome high temperatures and reduce fracture initiation and extension pressures. Screen completion and pumping of fracturing fluid into intervals where natural fractures develop is one of the primary measures. Formation rock is influenced by long-term geological action to form a plurality of natural fractures, and because the cementation degree is relatively low, if hydraulic fracturing is carried out on intervals where the natural fractures develop, the pressure is undoubtedly greatly reduced. As one of the EGS projects which are successful in the world, the French Soultz hot dry rock meets a natural fracture zone during artificial heat storage construction, so that the fracture initiation and extension pressure of a fracture is reduced. Therefore, accurately identifying the natural fracture development zone of the reservoir and adopting a proper fracturing process are the key points of the dry-hot rock fracturing. Currently, relatively little research is being done on hot dry rock fracturing methods.
SUMMERY OF THE UTILITY MODEL
The above-mentioned not enough to prior art exists, the utility model aims at providing a screen pipe cluster structure for hot dry rock fracturing to based on the hot dry rock reservoir natural fracture situation of developing, pertinence proposes well completion scheme, makes fracturing fluid concentrate in the high position of natural fracture development degree, is favorable to reducing the fracturing crack initiation and extends pressure and increase the crack scale.
In order to achieve the purpose, the utility model adopts the following technical proposal:
a sieve tube string structure for hot dry rock fracturing comprises a top joint and a bottom joint, wherein a first sieve tube corresponding to a first layer section of a hot dry rock reservoir, a second sieve tube corresponding to a second layer section of the hot dry rock reservoir and a solid non-porous tube corresponding to a third layer section of the hot dry rock reservoir are arranged between the top joint and the bottom joint; the fracture density of the first layer section is less than 1.8#/m, the fracture density of the second layer section is more than or equal to 1.8#/m, and the fracture density of the third layer section is not higher than; the first screen has a density of openings that is less than the density of openings of the second screen.
Furthermore, the first sieve tube is spirally provided with holes, the phase angle between the holes is 30 degrees, the hole diameter is 15mm, and the axial hole distance is 80 mm; the second sieve tube is also provided with holes in a spiral shape, the phase angle between the holes is 22.5 degrees, the hole diameter is 15mm, and the axial hole distance is 60 mm.
The utility model has the advantages that: the utility model is used for dry hot rock fracturing's screen pipe cluster structure combines the actual condition that the natural crack of reservoir develops to formulate the well completion scheme, makes fracturing fluid concentrate at the high position of natural crack development degree, is favorable to reducing the fracturing crack initiation and extends pressure and increase the crack scale.
Drawings
Fig. 1 is a schematic structural diagram of a screen pipe string structure for hot dry rock fracturing.
Fig. 2 is a schematic diagram of a first screen of the screen string structure for hot dry rock fracturing.
Fig. 3 is a schematic diagram of a second screen of the screen string structure for hot dry rock fracturing of the present invention.
Fig. 4 is a schematic diagram of the screen string structure for hot dry rock fracturing according to the present invention in practical application.
Fig. 5 is a schematic step diagram of the construction method of the screen string structure for hot dry rock fracturing of the present invention.
Detailed Description
The following describes in detail embodiments of the present invention with reference to the drawings.
As shown in fig. 1-4, the utility model provides a screen pipe string structure for hot dry rock fracturing, including top joint 1 and bottom joint 2, be equipped with the first screen pipe 4 that corresponds hot dry rock reservoir first layer section 3 between the two, correspond the second screen pipe 6 of hot dry rock reservoir second layer section 5 to and correspond the solid pipe 8 of sclausura of hot dry rock reservoir third layer section 7; the crack density of the first layer section 3 is less than 1.8#/m, the crack density of the second layer section 5 is more than or equal to 1.8#/m, and the crack density of the third layer section 7 is not higher than; the first screen 4 has a density of openings less than the density of openings of the second screen 6. Further, the first sieve tube 4 is spirally provided with holes, the phase angle between the holes is 30 degrees, the hole diameter is 15mm, and the axial hole distance is 80 mm; the second sieve tube 6 is also provided with holes in a spiral shape, the phase angle between the holes is 22.5 degrees, the hole diameter is 15mm, and the axial hole distance is 60 mm. The utility model discloses in, the solid pipe of sclausura 8 is ordinary oil casing (diameter 177.8mm, length 11.51m, steel grade P110), and the size and the material parameter of first, second screen pipe are also unanimous with the solid pipe of sclausura (diameter 177.8mm, length 11.51m, steel grade P110). The two sieve tubes are provided with different punching modes and hole densities according to different natural fracture development degrees of reservoirs, and conditions are created for hot dry rock fracturing through the combination of the two sieve tubes and a solid tube.
The utility model also provides a construction method that is used for dry hot rock fracturing's screen pipe cluster structure, includes the following step:
s1, selecting a fracturing horizon according to the dry heat rock reservoir displayed by the logging result;
s2, combining the top joint 1, the bottom joint 2 and the first sieve tube 4, the second sieve tube 6 and the solid pipe 8 between the top joint and the bottom joint through threads and putting the combined parts into a well, so that the first sieve tube 4, the second sieve tube 6 and the solid pipe 8 correspond to the first layer section 3, the second layer section 5 and the third layer section 7 of the hot dry rock reservoir respectively, and cementing the well above a target layer;
s3, preparing a fracturing fluid: preparing sufficient clear water, and preparing acid liquor with a certain concentration, slick water and a small amount of displacement liquid; the acid solution is high-temperature resistant earth acid and comprises 10% of hydrochloric acid, 10% of hydrofluoric acid and a high-temperature resistant material, and the slickwater is common viscous slickwater;
s4, chemical stimulation and thermal disruption: aiming at the characteristics of high temperature, high hardness and high quartz content of dry hot granite, firstly, less than 0.5m is adopted3Injecting acid liquor by a displacement pump at a displacement of/min to remove near-well pollution and corrode rocks, and then continuously adopting a pump with a volume of less than 0.5m3Injecting clear water by a displacement pump at the rate of/min to ensure that the reservoir rock is thermally cracked;
s5, variable-displacement multi-hydraulic pump injection: clean water, slick water and acid liquor are sequentially pumped by adopting a mode of step-up displacement, constant displacement and step-down displacement, and the initial displacement is 0.3-0.5 m3Min, the increase and decrease of the discharge capacity is less than 50 percent, and the maximum discharge capacity is not more than 3.5m3/min；
S6, pump injection of a displacement liquid: injecting a displacing liquid by using a constant displacement pump, and ejecting the acid liquid pumped in the S5 into the stratum;
s7, intermittent pump injection: and stopping the pump to relieve the pressure after the pump is filled with a certain amount of fracturing fluid, and circulating the steps S5, S6 and S7.
The utility model discloses on the basis of fully considering prior art condition and hot dry rock reservoir characteristic, increase the volume that the hot dry rock reservoir built, realize artifical heat-storage and build.
Further, in order to ensure the strength of the pipe string, the joints of the first screen pipe 4, the second screen pipe 6 and the solid pipes 8 without holes are 1.5m without holes, and the lowest ends of the bottom joints are two solid pipes which are used as sand settling pipes. As shown in fig. 4 and 5, in step S2, according to the natural fracture shown by the logging result, the first screen pipe 4 is inserted into the fracture section with discontinuous secondary development (the first layer section 3), the second screen pipe 6 is inserted into the continuous fracture section with relatively development (the second layer section 5), the solid pipe 8 without hole corresponds to the section without fracture development in the target layer (the third layer section 7), the standard of development and secondary development is a quantitative parameter of natural fracture tested by electrical imaging, the fracture density is greater than or equal to 1.8#/m and is considered as relatively developing natural fracture, and the fracture density is less than 1.8#/m and is considered as secondary development. By adopting the mode, the fracturing fluid is concentrated at the position with high development degree of the natural fracture, so that the fracture initiation and extension pressure of the fracture can be reduced, and the fracture scale can be increased.
It should be understood that the hot dry rock frac well set forth in the present disclosure is a vertical well, subject to the limitations of high temperature directional drilling techniques. Because the natural fractures are one of the prerequisites for fracturing fractures of the dry hot rock, the step S1 is to screen out the natural fractures randomly distributed in the dry hot rock reservoir by different logging means, the temperature of the dry hot rock reservoir is often more than 200 ℃, and the temperature amplitude is gradually increased along with the increase of the depth, so that the exploring tube for implementing the logging needs to resist the high temperature of 260 ℃, and the main logging items include: resistivity logging, acoustic imaging logging, electrical imaging logging, acoustic wave remote detection and radioactive logging can effectively identify natural fractures of the well wall.
Considering that the friction resistance gradually increases in the crack propagation process, in step S5, the fracturing fluids should be pumped and injected in the sequence of clear water, slickwater and acid liquor, the pumping sequence of each fracturing fluid should be followed by the step-up displacement, constant displacement and step-down displacement, and the step-up displacement stage pumps 80-100 m3The fracturing fluid is pumped and injected into the stage with constant discharge capacity of 150-200 m3The fracturing fluid is pumped to 40-60 m in the stage of step-down displacement3The fracturing fluid of (1). In step S6, the displacement pump has a filling amount of 40m3The displacement fluid is low-concentration common oil-based fracturing fluid. Considering that the high displacement amplification is at risk of inducing higher level micro-earthquakes, the step up displacement of the step S5In the process, when the discharge capacity is less than 2.5m3At the time of/min, the discharge capacity is increased by 40-50%. When the discharge capacity is increased to be more than 2.5m3At the time of/min, the discharge capacity is increased by 20-30%.
Considering the actual situation of the hot dry rock fracturing construction, the steps S5, S6 and S7 are the pumping content in one day, the pumping construction in the daytime and the pumping stopping and pressure relief in the night to form intermittent and slug type pumping, and the pumping liquid amount in one day is 1000m3And stopping the pump to release the pressure for not less than 10 hours, and circulating the pump to inject until the designed liquid amount is finished. The small-displacement, long-period, intermittent, multi-fluid and variable-displacement pump injection is the main characteristic of the hot dry rock fracturing.
It should be noted that the above mentioned embodiments are only preferred embodiments of the present invention, and the purpose is to make those skilled in the art better understand the present invention, and should not be used to limit the scope and application of the present invention, and any modification, equivalent replacement, improvement, etc. made within the spirit or principle of the present invention should be included in the protection scope of the present invention.
Claims (2)
1. A sieve tube string structure for hot dry rock fracturing is characterized by comprising a top joint and a bottom joint, wherein a first sieve tube corresponding to a first layer section of a hot dry rock reservoir, a second sieve tube corresponding to a second layer section of the hot dry rock reservoir and a solid non-porous tube corresponding to a third layer section of the hot dry rock reservoir are arranged between the top joint and the bottom joint; the fracture density of the first layer section is less than 1.8#/m, the fracture density of the second layer section is more than or equal to 1.8#/m, and the fracture density of the third layer section is not higher than; the first screen has a density of openings that is less than the density of openings of the second screen.
2. The screen string structure for hot dry rock fracturing of claim 1, wherein: the first sieve tube is spirally provided with holes, the phase angle between the holes is 30 degrees, the hole diameter is 15mm, and the axial hole distance is 80 mm; the second sieve tube is also provided with holes in a spiral shape, the phase angle between the holes is 22.5 degrees, the hole diameter is 15mm, and the axial hole distance is 60 mm.
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| CN202020214622.5U CN211950450U (en) | 2020-02-26 | 2020-02-26 | A screen pipe cluster structure for hot dry rock fracturing |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111206907A (en) * | 2020-02-26 | 2020-05-29 | 中国地质调查局水文地质环境地质调查中心 | Sieve tube string structure for hot dry rock fracturing and construction method thereof |
| CN113389537A (en) * | 2021-06-29 | 2021-09-14 | 太原理工大学 | Hot dry rock geothermal exploitation method for filling thermal reservoir in later stage of deep crack |
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2020
- 2020-02-26 CN CN202020214622.5U patent/CN211950450U/en active Active
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111206907A (en) * | 2020-02-26 | 2020-05-29 | 中国地质调查局水文地质环境地质调查中心 | Sieve tube string structure for hot dry rock fracturing and construction method thereof |
| CN113389537A (en) * | 2021-06-29 | 2021-09-14 | 太原理工大学 | Hot dry rock geothermal exploitation method for filling thermal reservoir in later stage of deep crack |
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