CN109441342B - Drilling acceleration method in shale formation - Google Patents
Drilling acceleration method in shale formation Download PDFInfo
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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
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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
- E21B10/00—Drill bits
- E21B10/08—Roller bits
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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
- E21B21/00—Methods or apparatus for flushing boreholes, e.g. by use of exhaust air from motor
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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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Abstract
The invention discloses a drilling acceleration method in a shale stratum, wherein for wells with unobvious drilling speed reduction after entering the shale stratum, low-viscosity drilling fluid which is periodically replaced can improve the washout capability of the shale stratum, shale cement which is bonded on a bottom drilling tool assembly is periodically cleaned, the probability of mud pocket phenomenon is greatly reduced, and further the effective application of drilling pressure to the stratum is ensured; for a well with a drilling speed obviously reduced after entering a shale reservoir, the cooperation of the heavy sweeping slurry and the heavy sweeping slurry is utilized, the rock debris which is attached to a well wall and is difficult to carry has extremely strong cleaning capacity, the cleaning degree in a shaft is greatly improved, the increased drilling pressure can be effectively acted to the well bottom through a drill bit, the problems of slow drilling speed and low drilling speed in the shale reservoir in the prior art are solved, the displacement effect of matching different drilling fluids through engineering means is realized, the drilling speed in the shale reservoir is improved, and the purpose of improving the engineering efficiency is achieved.
Description
Technical Field
The invention relates to the field of drilling engineering, in particular to a drilling acceleration method in a shale stratum.
Background
The shale gas refers to unconventional natural gas which is endowed in a reservoir rock system mainly containing organic-rich shale, is biochemical formation gas, thermal formation gas or a mixture of the biochemical formation gas and the thermal formation gas which are continuously generated, can exist in a free state in natural cracks and pores, exists on the surfaces of kerogen and clay particles in an adsorption state, and is stored in a very small amount in the kerogen and the asphaltene in a dissolved state, wherein the proportion of the free gas is generally 20-85%. Shale gas is natural gas extracted from shale layers, the main body of the shale gas is located in dark shale or high-carbon shale, the shale gas is natural gas which exists in shale, high-carbon shale, shale and silty rock interlayer in a free state or a free state on the main body of the natural gas in cracks, pores and other reservoir spaces in a free phase state (about 50%) at various stages of organic origin, the shale gas exists on the surfaces of kerogen, clay particles and pores in an adsorption state (about 50%), and the shale gas is stored in kerogen, asphaltene and petroleum in a dissolving state in a very small amount. Natural gas is also present in layered siltstone, siltstone mudstone, muddy siltstone, and even sandstone formations. After natural gas is produced, it accumulates nearby in the source formation, and behaves in a typical in-situ reservoir mode, with great differences from oil shale, oil sands, bitumen, and the like. Unlike conventional reservoir gas reservoirs, shale is both a source rock for natural gas generation and a reservoir and cap rock for gathering and storing natural gas. Therefore, black shale, high carbon mudstone, etc. with high organic content are often the best shale gas development conditions.
In recent years, the exploration and development of the shale gas in the world are in a rapid development situation under the influence of successful commercial development of the shale gas in the United states and Canada. However, due to the trapped pattern of shale gas in situ formations, the storage medium is a shale formation. For conventional oil and gas fields, shale rock stratums are geological structures serving as oil-producing layers or covering layers, so that the reservoir permeability of shale gas is extremely low, and the exploitation difficulty is high.
Firstly, the reservoir of the shale gas reservoir generally has the physical characteristics of low porosity and low permeability, the resistance of the gas flow is larger than that of the conventional natural gas, and all wells can be mined by performing reservoir fracturing modification. Secondly, the recovery ratio of the shale gas is lower than that of the conventional natural gas, the recovery ratio of the conventional natural gas is more than 60%, and the recovery ratio of the shale gas is only 5% -60%. The low production affects the enthusiasm of the individual, and there are several advanced technologies in the united states that can improve the production of shale gas wells. The reservoir of the Chinese shale gas reservoir is different from the United states, for example, the burial depth of the shale gas layer of the Sichuan basin is larger than that of the United states, the depth of the shale gas layer of the United states is 800-2600 meters, and the burial depth of the shale gas layer of the Sichuan basin is 2000-3500 meters. The increase of the shale gas layer depth undoubtedly adds development difficulty on the immature mining technology in China. Specifically, in drilling engineering, a standard shale reservoir is different from a shale stratum with insufficient compaction degree, but is a compact stratum which is fully compacted and deposited, and has the characteristics of compactness, full cementation, high hardness, low drillability, weak slurrying capacity and the like in lithology. The combination of these features shows slow drilling and low drilling speed in drilling engineering. In the prior art, an effective method aiming at the slow drilling time of the shale reservoir is not available, and the shale reservoir can only be drilled slowly by depending on large drilling pressure, so that the engineering efficiency is low, and the cost of manpower and material resources is wasted.
Disclosure of Invention
The invention aims to provide a drilling acceleration method in a shale reservoir to solve the problems of slow drilling speed and low drilling speed in the shale reservoir in the prior art and achieve the purposes of improving the drilling speed in the shale reservoir and improving the engineering efficiency.
The invention is realized by the following technical scheme:
a method of accelerating drilling in a shale formation, comprising the steps of:
(a) drilling to a position 5-10 m vertical depth away from the top of the shale reservoir by using a PDC drill bit according to a designed well track, wherein the viscosity of the drilling fluid is A in the drilling process and the unit centipoise; the density is B, unit g/cm3(ii) a Counting the average drilling speed of nearly 24 hours in the drilling process as X in m/h; the average rotating speed of the drill rod is Y, and the unit rpm is; the average weight on bit is Z, unit ton; the average discharge capacity is Q, and the unit is L/min; circulating, tripping, replacing the drill bit with a tricone bit with the same diameter as the PDC drill bit, and using a new screw drilling tool in the bottom drilling tool assembly;
(b) drilling down to the bottom of the well, detecting the settled sand, drilling into the shale reservoir, continuing drilling at the rotating speed Y, the drilling pressure Z and the discharge Q, and monitoring the average drilling speed X in the shale reservoir within one hour1If X is1Not less than X or X1If the/X is more than or equal to 0.8, continuously drilling at the rotating speed Y, the bit pressure Z and the discharge Q, and replacing 0.8-1.5 m into the drill rod every two hours3A slurry with a viscosity of 0.5A; if X1the/X is less than 0.8, and the step (c) is carried out;
(c) lifting the drill bit off the well bottom, keeping the discharge Q unchanged, and reducing the rotating speed to Y1，Y10.7-0.8, and increasing the bit pressure to Z1，Z1Continuing drilling to obtain the drilling speed X at the moment when the/Z is 1.2-1.82；
(d) If X2＞X1Then the displacement Q and the rotation speed Y are maintained1Weight on bit Z1Drilling is continued, and X is updated every hour2(ii) a If X2≤X1Sequentially replacing 1-2 m into the drill rod3Heavy pulp with density of 1.5-2B and thickness of 1-2 m3The thick slurry with the viscosity of 1.5-2A is judged according to the pump stroke number, when the heavy slurry and the thick slurry are discharged from the drill bit, the drill bit is lifted away from the bottom of the well, and then the discharge capacity Q and the rotating speed Y are used1Weight on bit Z1Drilling is continued, and X is updated every hour2；
(e)X2And (d) carrying out judgment after each updating.
In the prior art, drilling is slow in a shale reservoir, the drilling speed is low, and due to the extremely weak slurrying capacity of the shale reservoir and the extremely low rock permeability of a shale stratum section, in a shale gas reservoir section in a drilling process, drilling fluid cannot be naturally dehydrated on a well wall to form complete mud cakes, the mud cakes are insufficient, lubrication and buffering between a drilling tool and the well wall are lack, and friction resistance is extremely high. The invention provides a drilling acceleration method in a shale stratum on the basis, the method comprises the steps of normally drilling according to a designed borehole trajectory by using a PDC drill bit before entering the shale stratum, and rapidly drilling an upper stratum by using the excellent cutting performance of the PDC drill bit before entering the shale stratum. Stopping drilling at a position 5-10 m vertical depth away from the top of the shale reservoir to obtain the viscosity A and the density B of the drilling fluid in the drilling process; drilling parameters such as the average drilling speed X, the average rotating speed of a drill rod Y, the average drilling pressure Z and the average discharge capacity Q within about 24 hours are reserved, then circulation is carried out until rock debris at the bottom of a well returns to the well head, the requirement of rock debris logging is met, and the rock debris in the well circulates until the requirement of tripping is met, then tripping is carried out, and the bottom drilling tool combined BHA is replaced, wherein the specific replacement content is as follows: and replacing the bit with a tricone bit with the same diameter as the PDC bit, and using a new screw drill in the bottom hole assembly. If the screw drilling tool is used before, a new screw is replaced, if the screw drilling machine is not used before, a new screw is added, and the new screw drilling tool is replaced, so that enough bottom power is ensured when the shale reservoir is drilled in the well at this time. Change PDC drill bit for tricone bit because PDC drill bit has higher drilling ability, but that is to ordinary stratum, the diamond compact piece on the PDC drill bit can cooperate high rotational speed, and quick carry out the successive layer cutting to the stratum, and this kind of broken rock mode is in the shale rock stratum, because very high compaction degree and compactness of shale rock stratum, can lead to cutting effect not good, and PDC drill bit inefficacy is very fast, need frequently play to playThe drill is replaced. The rock breaking mechanism of the tricone bit is breaking rather than cutting, namely, the cone is eaten into the stratum by utilizing the gravity of a drilling tool, the stratum at the lower part is directly crushed integrally instead of cutting layer by layer, and the rock breaking mode looks like the traditional mode and is more beneficial to the drilling effect in the shale stratum. Therefore, the method abandons the method of pursuing high drilling speed by using the PDC drill bit in the prior art, but specially starts drilling to replace the tricone drill bit, and overcomes the technical bias that the PDC drill bit is inevitably faster than the drilling speed of the roller bit in the prior art. After the drill bit and the screw drill tool are replaced, the well is drilled to the bottom of the well, the settled sand is detected, the shale reservoir is drilled, the drilling is continued at the rotating speed Y, the drilling pressure Z and the discharge Q, and the average drilling speed X in the shale reservoir within one hour is monitored1If X is1Not less than X or X1the/X is more than or equal to 0.8, which shows that the drilling speed is not reduced or the reduction amplitude is small after the shale reservoir stratum enters, and belongs to the result of normal influence of the shale drillability, the drilling is continued at the rotating speed Y, the drilling pressure Z and the discharge Q, and 0.8-1.5 m is replaced into the drill rod every two hours3A slurry with a viscosity of 0.5A. Continuously drilling, and replacing the drill rod with a distance of 0.8-1.5 m every two hours3A slurry with a viscosity of 0.5A. In the drilling process in the shale reservoir, a certain amount of slurry is periodically replaced, the slurry is low-viscosity drilling fluid, the specific viscosity is 0.5A, and the specific viscosity is only half of the viscosity of the drilling fluid in normal drilling. The reason why the slurry is periodically replaced is that the inventor of the application researches that in order to overcome the defect that the slurrying capability of the shale rock stratum is weak, the viscosity of a drilling fluid system in the shale reservoir in the prior art is generally high, so that the erosion capability of the drilling fluid on the stratum and rock debris is weak. In addition, due to the characteristic of compact cementation of the shale reservoir, the cementing materials in the shale are easily adhered to the bottom drilling tool assembly, and further, the bit pressure cannot be effectively applied to the stratum, and even mud pockets are induced when the bit pressure is severe. In the invention, the low-viscosity slurry is replaced every two hours, and the replacing amount is only 0.8-1.5 m3And under the normal drilling displacement, the oil can be quickly returned through the annular space, and the stability of the well wall cannot be influenced. After slurry is discharged from the drill bit each time, the low-viscosity characteristic of the slurry is firstly utilized to enter the lower stratumThe strong impact is performed, and the erosion capacity to the stratum is improved instantly. Secondly, the cementing materials in the shale reservoir coated on the outer surface of the bottom drilling tool are diluted and dispersed by utilizing the slurry, so that various cementing materials are separated from the surface of the drilling tool and suspended in the annular space, and are convenient to be carried and returned by the drilling fluid. If X1and/X is less than 0.8, which shows that the drilling rate is obviously reduced after the shale reservoir is entered, and then the shale reservoir enters the step (c) to be treated according to the process method in the steps (c) to (d). The step (c) is as follows: lifting the drill bit off the well bottom, keeping the discharge Q unchanged, and reducing the rotating speed to Y1，Y10.7-0.8, and increasing the bit pressure to Z1，Z1Continuing drilling to obtain the drilling speed X at the moment when the/Z is 1.2-1.82(ii) a Namely, in the step (c), the drill bit is lifted away from the well bottom to adjust the rotating speed, the rotating speed is reduced to 0.7-0.8 time of the original rotating speed Y, and then the drill bit is contacted with the well bottom to drill with the large drilling pressure of 1.2-1.8 times of the original drilling pressure Z. By utilizing drilling parameters of large bit pressure and low rotating speed, the large bit can fully press the bottom ends of the cones of the tricone bit into the stratum, and then the large bit is matched with the low rotating speed to ensure that the cones rotate at a low speed in the stratum to gradually crush and break the stratum, thereby avoiding the problems that the shale layer is cemented compactly, the high rotating speed causes the cone bit to slip in the stratum and the force effect is poor. The applied large drilling pressure can be fully acted in the stratum instead of being used for overcoming friction resistance to rotate at high speed, and the rock breaking capacity of the roller bit is greatly improved. Therefore, in the step (c), the large drilling pressure is sufficiently applied to the interior of the stratum by utilizing a drilling parameter mode that the large drilling pressure is matched with the low rotating speed, so that the tricone bit can sufficiently exert the rock breaking mechanism of the tricone bit and gradually crush and break the lower stratum, the drilling parameters are optimized, and the drilling capacity in the shale reservoir is improved. This is obtained after adjusting the drilling parameters in step (c)The drilling speed is X2(ii) a Then by step (d) for X2Making a comparison if X2＞X1Indicating that good results have been achieved in adjusting the drilling parameters, thus maintaining the displacement Q, the speed of rotation Y1Weight on bit Z1Drilling is continued, and X is updated every hour2(ii) a If X2≤X1The problem that the drilling pressure cannot be directly and effectively loaded on a drill bit at the moment is that the drilling capacity of the shale reservoir cannot be effectively improved by adjusting the drilling parameters, and therefore 1-2 m of drilling pressure can be sequentially replaced into a drill rod3Heavy pulp with density of 1.5-2B and thickness of 1-2 m3The thick slurry with the viscosity of 1.5-2A is judged according to the pump stroke number, when the heavy slurry and the thick slurry are discharged from the drill bit, the drill bit is lifted away from the bottom of the well, and then the discharge capacity Q and the rotating speed Y are used1Weight on bit Z1Drilling is continued, and X is updated every hour2. That is, 1 to 2m is substituted3The heavy slurry with the density of 1.5B-2B is immediately replaced by 1-2 m3The viscosity of the thick slurry is 1.5-2A. The first replaced heavy slurry with density of 1.5-2B is high-density drilling fluid, the suspension capacity of the drilling fluid to rock debris is controlled by viscosity and is in positive correlation with the density of the drilling fluid, therefore, in the invention, the first replaced heavy slurry can effectively lift the rock debris attached to a well wall, so that the rock debris which cannot be carried by the drilling fluid with conventional density and is laid on the well wall is also lifted by the heavy slurry to enter the air, and then the rock debris lifted by the heavy slurry is further carried to a well mouth to be discharged along with the arrival of subsequent thick slurry by utilizing the characteristic of the thick slurry, therefore, by utilizing the matching of the sweeping heavy slurry and the sweeping thick slurry, the invention has extremely strong cleaning capacity to the rock debris which is attached to the well wall and difficult to be carried, particularly for a directional well, the rock debris accumulation at a low position of a well hole track can be effectively eliminated, and the cleaning degree in a well bore can be greatly improved, therefore, the friction resistance of the whole drilling tool is obviously reduced, the increased bit pressure can be effectively acted to the bottom of the well through the drill bit, and the drilling speed is improved. The density of the thick slurry is preferably the same as that of the heavy slurry, so that the thick slurry has high viscosity and high density, and can effectively clean rock debris in the well at one time. Due to the pumpThe stroke is known, the drilling rod internal diameter is known, therefore according to the pump stroke number, the technical staff in the art can judge when heavy thick liquid, thick liquid go out the drill bit, when heavy thick liquid goes out the drill bit with thick liquid, lift the drill bit off the shaft bottom, in order to avoid carrying many detritus suddenly and lead to the increase of annular space obstructed pump pressure, if the drill bit is at the shaft bottom this moment, the drilling tool does not have the space of downward activity, upward activity has the risk of lifting the card dead drilling tool of card again under the card again, therefore lift the drill bit off the shaft bottom when heavy thick liquid goes out the drill bit and can effectively guarantee the downhole safety to the in-process of detritus clearance in the well, make the drilling tool have the space of transferring. X2And (d) judging after updating every time, and then carrying out judgment in the step (d), so that once the drilling speed is reduced in the last hour, cleaning the well by replacing heavy slurry and thick slurry, and ensuring that the drilling pressure can be effectively loaded on the stratum through a drill bit, thereby solving the problems of slow drilling speed and low drilling speed in the shale reservoir in the prior art, and realizing the purposes of improving the drilling speed in the shale reservoir and improving the engineering efficiency by means of engineering and matching with the replacement effect of different drilling fluids.
Preferably, the discharge capacity for replacing heavy slurry and thick slurry in the step (d) is Q ', and the Q'/Q is 0.6-0.7; and after the thick slurry is completely returned from the wellhead, increasing the discharge capacity to Q again. The low-displacement is used for replacing the heavy slurry and the thick slurry, so that the heavy slurry and the thick slurry can slowly flow in the annular space, the cuttings attached to the well wall are lifted and carried more sufficiently, and the sand-carrying cleaning effect is further improved.
Preferably, the discharge capacity of the slurry replaced in the step (b) is Q ', and the Q'/Q is 1.2-1.4; and after the slurry is completely returned from the wellhead, reducing the discharge capacity to Q again. That is, the slurry is displaced at a high displacement, first causing the slurry to have greater kinetic energy as it exits the drill bit, thereby providing greater washout capability of the formation. And secondly, the slurry can be returned out of the wellhead more quickly, and the stability in the well is maintained.
Preferably, the slurry returns from the wellhead and does not enter a drilling fluid circulating pool after being screened by a vibrating screen. The slurry is prevented from being mixed into the circulating pool to be mixed with the conventional drilling fluid, so that the performance of the drilling fluid is further influenced. The slurry which is environment-friendly and does not contain oil gas and can be directly discharged; otherwise, the sewage is uniformly recovered through the sewage tank for treatment.
Preferably, in the step (b), the rotating speed of the drilling tool is increased when the slurry is judged to be discharged out of the drill bit according to the pump stroke number; and after the slurry returns from the wellhead, the rotating speed is adjusted back to Y. Through the high rotational speed of drilling tool, exert bigger centrifugal force for detritus cementite etc. that adheres to on the drilling tool, the erosion and the dilution of cooperation slurry for the detritus cementite that adheres to on the drilling tool more effectually breaks away from the drilling tool surface, effect when further improving the displacement slurry.
Compared with the prior art, the invention has the following advantages and beneficial effects:
1. according to the drilling acceleration method in the shale stratum, the cone is enabled to be eaten into the stratum by utilizing the gravity of the drilling tool, the integral crushing is directly carried out on the stratum at the lower part, the cutting is not carried out layer by layer, the rock breaking mode looks like the traditional mode, and the drilling effect in the shale stratum is better. Therefore, the method abandons the method of pursuing high drilling speed by using the PDC drill bit in the prior art, but specially starts drilling to replace the tricone drill bit, and overcomes the technical bias that the PDC drill bit is inevitably faster than the drilling speed of the roller bit in the prior art.
2. According to the drilling acceleration method in the shale stratum, the large drilling pressure is fully applied to the inside of the stratum by utilizing the drilling parameter mode that the large drilling pressure is matched with the low rotating speed, so that the tricone bit can fully exert the rock breaking mechanism of the tricone bit and gradually crush and break the lower stratum, the drilling parameter is optimized, and the drilling capacity in the shale stratum is improved.
3. For wells with unobvious drilling speed reduction after entering the shale reservoir, the drilling fluid with low viscosity which is periodically replaced can improve the washout capability of the shale reservoir, and shale cement which is adhered on a bottom drilling assembly is periodically cleaned, so that the possibility of the occurrence of the mud pocket phenomenon is greatly reduced, and further, the effective application of the drilling pressure to the stratum is ensured, and the drilling speed can be stabilized at a relatively high level in the drilling process of the shale reservoir.
4. The drilling acceleration method in the shale reservoir provided by the invention has the advantages that for a well with obviously reduced drilling speed after entering the shale reservoir, the cooperation of the heavy sweeping slurry and the heavy sweeping slurry is utilized, the cleaning capability for the hard-to-carry rock debris attached to the well wall is extremely strong, particularly for a directional well, the rock debris accumulation at the low position of the well track can be effectively eliminated, the cleaning degree in the well shaft can be greatly improved, the friction resistance borne by the whole drilling tool is obviously reduced, the increased drilling pressure can be effectively acted to the well bottom through the drill bit, the drilling speed is improved, the problems of slow drilling speed and low drilling speed in the shale reservoir in the prior art are solved, and the purposes of improving the drilling speed in the shale reservoir and improving the engineering efficiency by means and matching with the displacement effect of different drilling fluids are realized.
Drawings
The accompanying drawings, which are included to provide a further understanding of the embodiments of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principles of the invention. In the drawings:
FIG. 1 is a schematic flow chart of an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to examples and accompanying drawings, and the exemplary embodiments and descriptions thereof are only used for explaining the present invention and are not meant to limit the present invention.
Example 1:
a method of accelerating drilling in a shale formation as illustrated in fig. 1, comprising the steps of:
(a) drilling to a position 5-10 m vertical depth away from the top of the shale reservoir by using a PDC drill bit according to a designed well track, wherein the viscosity of the drilling fluid is A in the drilling process and the unit centipoise; the density is B, unit g/cm3(ii) a Counting the average drilling speed of nearly 24 hours in the drilling process as X in m/h; the average rotating speed of the drill rod is Y, and the unit rpm is; the average weight on bit is Z, unit ton; the average discharge capacity is Q, and the unit is L/min; circulation, tripping, replacing drill bit with PDC drill bit or the likeA tricone bit with a diameter, and a new screw drill is used in the bottom drill assembly;
(b) drilling down to the bottom of the well, detecting the settled sand, drilling into the shale reservoir, continuing drilling at the rotating speed Y, the drilling pressure Z and the discharge Q, and monitoring the average drilling speed X in the shale reservoir within one hour1If X is1Not less than X or X1If the/X is more than or equal to 0.8, continuously drilling at the rotating speed Y, the bit pressure Z and the discharge Q, and replacing 0.8-1.5 m into the drill rod every two hours3A slurry with a viscosity of 0.5A; if X1the/X is less than 0.8, and the step (c) is carried out;
(c) lifting the drill bit off the well bottom, keeping the discharge Q unchanged, and reducing the rotating speed to Y1，Y10.7-0.8, and increasing the bit pressure to Z1，Z1Continuing drilling to obtain the drilling speed X at the moment when the/Z is 1.2-1.82；
(d) If X2＞X1Then the displacement Q and the rotation speed Y are maintained1Weight on bit Z1Drilling is continued, and X is updated every hour2(ii) a If X2≤X1Sequentially replacing 1-2 m into the drill rod3Heavy pulp with density of 1.5-2B and thickness of 1-2 m3The thick slurry with the viscosity of 1.5-2A is judged according to the pump stroke number, when the heavy slurry and the thick slurry are discharged from the drill bit, the drill bit is lifted away from the bottom of the well, and then the discharge capacity Q and the rotating speed Y are used1Weight on bit Z1Drilling is continued, and X is updated every hour2；
(e)X2And (d) carrying out judgment after each updating.
Taking a certain shale gas trap in south-west province of Chuan Qing drilling contract as an example, comparing three adjacent wells with very close geological conditions, taking one adjacent well as a reference well, and using a conventional operation method, the drilling parameters of the shale reservoir layer with the PDC drill bit are as follows: the viscosity of the drilling fluid is 60cp, and the density of the drilling fluid is 1.20g/cm3The average drilling speed X is 10.4m/h, and the average rotating speed Y of a drill rod is 60 rpm; the average weight on bit Z is 8 tons; the average discharge capacity Q is 3800L/min. And the other two wells are used as comparison wells, construction is carried out by using the method in the embodiment, wherein one comparison well is subjected to X-ray after the tricone bit is replaced1Since it is 7.1m/h, the process proceeds to steps (c) to (d) and adjustment is made by taking Y1At 45rpm, Z1Is 12 tons, X is obtained2Is 12.3 m/h. After drilling for 10 hours, X2The decrease was 7.4m/h, thus replacing 2m3The density was 2.0g/cm3Heavy pulp, 2m3And (3) finishing the replacement of the thick slurry with the viscosity of 100cp, and after the heavy slurry and the thick slurry are fully returned out, increasing the drilling speed to 15.8 m/h. After the tricone bit is replaced in another contrast well, X110.1m/h, and has very small difference with the original drilling speed X, so that the original drilling parameters are kept to continue drilling, and 1m of drilling rod is replaced into the drilling rod every two hours3And after each replacement of the slurry with the viscosity of 30cp is finished, the drilling speed is increased by 4-5 m/h in the next hour.
Example 2:
in a drilling acceleration method in a shale formation as shown in fig. 1, on the basis of embodiment 1, the displacement volume when heavy and thick slurry is replaced in step (d) is Q ', and Q'/Q is 0.6; and after the thick slurry is completely returned from the wellhead, increasing the discharge capacity to Q again. The discharge capacity when the slurry is replaced in the step (e) is Q ', wherein Q'/Q is 1.4; and after the slurry is completely returned from the wellhead, reducing the discharge capacity to Q again. And the slurry returns out from the wellhead and does not enter a drilling fluid circulating pool after rock debris is screened by the vibrating screen. And after the thin slurry is screened from the rock debris by the vibrating screen, the thin slurry enters a sump oil tank to be recovered.
The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are merely exemplary embodiments of the present invention, and are not intended to limit the scope of the present invention, and any modifications, equivalent substitutions, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (5)
1. A method of accelerating drilling in a shale formation, comprising the steps of:
(a) drilling to a position 5-10 m vertical depth away from the top of the shale reservoir by using a PDC drill bit according to a designed well track, wherein the viscosity of the drilling fluid is A in the drilling process and the unit centipoise; the density is B, unit g/cm3(ii) a Counting the average drilling speed of nearly 24 hours in the drilling process as X in m/h; the average rotating speed of the drill rod is Y, and the unit rpm is; the average weight on bit is Z, unit ton; the average discharge capacity is Q, and the unit is L/min; circulating, tripping, replacing the drill bit with a tricone bit with the same diameter as the PDC drill bit, and using a new screw drilling tool in the bottom drilling tool assembly;
(b) drilling down to the bottom of the well, detecting the settled sand, drilling into the shale reservoir, continuing drilling at the rotating speed Y, the drilling pressure Z and the discharge Q, and monitoring the average drilling speed X in the shale reservoir within one hour1If X is1If the/X is larger than or equal to 0.8, continuing drilling at the rotating speed Y, the drilling pressure Z and the discharge capacity Q, and replacing the thin slurry with the thinning pulp with the 0.5A of 0.8-1.5 m of high-speed plantation viscosity into the drill rod every two hours; if X1the/X is less than 0.8, and the step (c) is carried out;
(c) lifting the drill bit off the well bottom, keeping the discharge Q unchanged, and reducing the rotating speed to Y1，Y1Y =0.7~0.8, while increasing the weight on bit to Z1，Z1the/Z = 1.2-1.8, and the drilling is continued to obtain the drilling speed X at the moment2；
(d) If X2＞X1Then the displacement Q and the rotation speed Y are maintained1Weight on bit Z1Drilling is continued, and X is updated every hour2(ii) a If X2≤X1Sequentially replacing heavy slurry with the density of 1.5B-2B and thick slurry with the viscosity of 1.5A-2A into the drill rod, lifting the drill bit away from the bottom of the well when judging that the heavy slurry and the thick slurry are discharged out of the drill bit according to the pump stroke number, and then lifting the drill bit at the discharge capacity Q and the rotation speed Y1Weight on bit Z1Drilling is continued, and X is updated every hour2；
（e）X2And (d) carrying out judgment after each updating.
2. The method of claim 1, wherein the displacement volume for replacing the heavy and thick slurry in step (d) is Q ', wherein Q'/Q = 0.6-0.7; and after the thick slurry is completely returned from the wellhead, increasing the discharge capacity to Q again.
3. A method of accelerating drilling into a shale formation as claimed in claim 1, wherein displacement of the slurry in step (b) is Q ", said Q"/Q = 1.2-1.4; and after the slurry is completely returned from the wellhead, reducing the discharge capacity to Q again.
4. The method of claim 1, wherein the slurry is returned from the wellhead and screened through the shaker screen against cuttings before entering the drilling fluid circulation sump.
5. The method of claim 1, wherein in step (b), the rotational speed of the drilling tool is increased when the slurry exits the drill bit as determined by the pump stroke count; and after the slurry returns from the wellhead, the rotating speed is adjusted back to Y.
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| US9663995B2 (en) * | 2013-04-17 | 2017-05-30 | Baker Hughes Incorporated | Drill bit with self-adjusting gage pads |
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| WO2012080819A2 (en) * | 2010-12-13 | 2012-06-21 | Schlumberger Technology B.V. (Stbv) | Optimized drilling |
| CN103046918A (en) * | 2011-10-13 | 2013-04-17 | 中国石油天然气集团公司 | Method and system for optimizing drilling parameters |
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Effective date of registration: 20200820 Address after: 257000 Six Drilling Stems in Shengli Oilfield, Dongying District, Dongying City, Shandong Province Patentee after: SHENGLI OILFIELD BOYOU MUD TECHNOLOGY Co.,Ltd. Address before: 610000 Shiyang Industrial Park, hi tech Zone, Chengdu, Sichuan Patentee before: CHENGDU KESHENG PETROLEUM TECHNOLOGY Co.,Ltd. |
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Denomination of invention: A method of accelerating drilling in shale formation Effective date of registration: 20230307 Granted publication date: 20200407 Pledgee: Dongying laishang Village Bank Co.,Ltd. Xindian sub branch Pledgor: SHENGLI OILFIELD BOYOU MUD TECHNOLOGY CO.,LTD. Registration number: Y2023980034153 |