High-pressure-bearing leaking stoppage slurry and pressure-bearing capacity evaluation method based on 3D printing artificial core

Abstract

The invention relates to the technical field of well drilling leaking stoppage fluid and pressure bearing capacity evaluation methods, in particular to high-pressure-bearing leaking stoppage slurry and a pressure bearing capacity evaluation method based on a 3D printing artificial rock core. The high-pressure-bearing leaking stoppage slurry comprises water, fine walnut shells, plant fibers, inorganic rigid particles and gel; the inorganic rigid particles are composed of leaking stoppage materials with different particle sizes, different types and different strengths. According to the method, an existing QD-2 leaking stoppage instrument is transformed, the 3D printing technology is combined to simulate the width and the surface roughness of the rock core crack, and the pressure bearing capacity evaluation method which is better in crack simulation reduction degree and higher in experiment credibility is formed. Wherein the high-pressure-bearing leaking stoppage slurry is composed of leaking stoppage materials with different particle sizes, different types and different strengths, a high-strength leaking stoppage layer can be formed, so that the pressure-bearing capacity of a stratum is improved, the pressure-bearing capacity of the leaking stoppage layer formed by the high-pressure-bearing leaking stoppage slurry is evaluated in combination with a pressure-bearing capacity evaluation method, and real simulation of underground conditions can be better achieved.

Description

Technical Field

[0001] The invention relates to the technical field of drilling plugging fluid and pressure bearing capacity evaluation method, in particular to a high-pressure plugging slurry and a 3D printed artificial core and a pressure bearing capacity evaluation method based on the 3D printed artificial core. Background Art

[0002] Well leakage refers to the phenomenon that the drilling fluid partially or completely leaks into the formation during the drilling process. When the amount of drilling fluid loss is large, the mud level in the wellbore annulus will decrease. As the mud level decreases, the bottom hole pressure may become insufficient to balance the fluid pressure from the formation, causing the formation fluid to flow into the wellbore, that is, fluid kick, and well control problems.

[0003] Indoor plugging evaluation method is an important experimental means to evaluate the effect of drilling fluid and plugging materials. For the indoor experiment of formation pressure bearing capacity, the methods used at home and abroad to evaluate the pressure bearing capacity of formations are mostly evaluated by plugging evaluation means, such as the JLX-2 dynamic plugging tester pressure bearing capacity evaluation method, DL-1 plugging test device, HTHP plugging simulation test device, etc. However, this type of evaluation simulation medium can only reflect the characteristics of formation straight fractures and large-scale inclined fractures, and cannot accurately reflect the real structure of the formation with tortuous and interlaced networks. Therefore, it is urgent to develop a pressure bearing capacity evaluation method with better restoration of fracture simulation and higher experimental credibility. Summary of the invention

[0004] The present invention provides a high-pressure plugging slurry and a pressure-bearing capacity evaluation method based on 3D printed artificial cores, which overcome the shortcomings of the above-mentioned prior art. The core is obtained by 3D printing technology, and its degree of restoration of fracture simulation is better; the high-pressure plugging slurry can form a high-strength plugging layer, thereby improving the pressure-bearing capacity of the formation. The pressure-bearing capacity of the plugging layer formed by the high-pressure plugging slurry is evaluated in combination with the pressure-bearing capacity evaluation method, which can better realize the true simulation of the underground situation.

[0005] One of the technical solutions of the present invention is achieved by the following measures: a high-pressure plugging slurry, comprising, by weight, 100 parts of water, 2 to 8 parts of fine walnut shells, 2 to 6 parts of plant fibers, 15 to 25 parts of inorganic rigid particles, and 2 to 6 parts of gel; The plant fiber particle size is 0.15 mm to 0.28 mm; The particle size of the fine walnut shell powder is 0.42 mm to 0.85 mm; The inorganic rigid particles include inorganic rigid particles I with a particle size of 0.45 mm to 2 mm, inorganic rigid particles II with a particle size of 0.28 mm to 0.9 mm, inorganic rigid particles III with a particle size of 0.18 mm to 0.45 mm, and inorganic rigid particles IV with a particle size of 0.15 mm to 0.28 mm; The gel is ZND-2 gel.

[0006] The following is a further optimization and / or improvement of one of the above-mentioned technical solutions: Furthermore, the inorganic rigid particle material is marble.

[0007] Furthermore, the weight ratio of the inorganic rigid particles I, the inorganic rigid particles II, the inorganic rigid particles III and the inorganic rigid particles IV is 1:1:1:1.

[0008] Furthermore, the high-pressure plugging slurry is prepared according to the following method: gel, fine walnut shells, plant fibers and inorganic rigid particles are sequentially added to water under stirring to obtain the high-pressure plugging slurry.

[0009] The second technical solution of the present invention is achieved by the following measures: a 3D printed artificial core, comprising a core assembly and a high temperature resistant core sleeve (3), wherein the core assembly comprises a 3D printed splicing block (1) for fixing the width of the crack at the top of the core and a 3D printed splicing block (2) for fixing the width of the crack at the bottom of the core; wherein the 3D printed splicing block (1) for fixing the width of the crack at the top of the core, the 3D printed splicing block (2) for fixing the width of the crack at the bottom of the core, and the high temperature resistant core sleeve (3) are assembled together to form a cylinder; the crack at the top of the core One side of the width-fixed 3D printed splicing block (1) and one side of the crack width-fixed 3D printed splicing block (2) at the bottom of the core are both designed to simulate the rough surface of the rock, and the concave and convex parts of the rough surfaces of the two opposite sides are correspondingly fitted together and assembled together to form a cylinder. The high-temperature resistant core sleeve (3) is wrapped around the outside of the core to fix the core into a cylindrical shape, so that a gap is left between the opposite surfaces of the crack width-fixed 3D printed splicing block (1) at the top of the core and the crack width-fixed 3D printed splicing block (2) at the bottom of the core.

[0010] The following is a further optimization and / or improvement of the second technical solution of the above invention: Furthermore, the 3D printed splicing block (1) for fixing the crack width of the upper core, the 3D printed splicing block (2) for fixing the crack width of the lower core, and the high temperature resistant core sleeve (3) are all made of 3D printed materials, and the 3D printed materials are high temperature resistant soluble resins.

[0011] Furthermore, the 3D printer used for the core upper crack width fixed 3D printed splicing block (1), the core lower crack width fixed 3D printed splicing block (2) and the high temperature resistant core sleeve (3) is a light-curing 3D printer FARSOON HT251P.

[0012] Furthermore, the lengths of the 3D printed splicing block (1) for fixing the crack width of the upper core, the 3D printed splicing block (2) for fixing the crack width of the lower core, and the high temperature resistant core sleeve (3) are all 55 mm, and the cross-sectional diameter of the cylinder spliced ​​by the 3D printing is 44 mm; the outer diameter of the high temperature resistant core sleeve (3) is 45 mm, and the inner diameter is 44 mm.

[0013] Furthermore, the distance between the opposing surfaces of the 3D printed splicing block (1) for fixing the crack width of the upper core and the 3D printed splicing block (2) for fixing the crack width of the lower core is 1 mm to 5 mm.

[0014] The third technical solution of the present invention is achieved by the following measures: a method for evaluating the pressure bearing capacity based on a 3D printed artificial core using the high pressure plugging slurry described in the first technical solution, wherein the 3D printed artificial core is the 3D printed artificial core described in the second technical solution; the pressure bearing capacity evaluation method is performed according to the following steps: Step 1: Before the experiment, the core components of the 3D printed artificial core are assembled and buckled to form a core, and a high-temperature resistant core sleeve (3) is wrapped around the outside of the core to fix the core into a cylindrical shape, ensuring that each core component will not be scattered during the process of being placed in the core holder of the plugging instrument, and then placed in the core holder; Step 2: Inject the prepared drilling fluid containing high-pressure plugging slurry into the sleeve of the plugging instrument, and the drilling fluid in the sleeve passes through the ball valve and core holder of the reverse flow device in sequence; Step 3: Adjust the pressure in the sleeve of the plugging instrument and the connected structure, and increase the pressure value from low to high with a starting pressure of 0.5 MPa. After the pressure in the sleeve reaches a certain value, the drilling fluid will pass through the 3D printed artificial core and be discharged into the collection tube; the single increase value is 0.5 MPa and the pressure is maintained for 2 minutes and the volume of the discharged drilling fluid is recorded. When the volume of the discharged drilling fluid suddenly increases, the highest pressure value before the discharge is recorded; Step 4: After recording the maximum breakthrough pressure of the drilling fluid and the leakage volume over a certain period of time, close the connecting valve stem, turn off the gas supply and release the pressure.

[0015] The following is a further optimization and / or improvement of the third technical solution of the above invention: Furthermore, the inner diameter of the core holder of the reverse discharge device of the plugging instrument is 45.1 mm.

[0016] The present invention provides a high-pressure plugging slurry and a pressure-bearing capacity evaluation method based on 3D printed artificial cores. By modifying the existing QD-2 plugging instrument and combining 3D printing technology to simulate the width and surface roughness of the core cracks, a pressure-bearing capacity evaluation method with better restoration of crack simulation and higher experimental credibility is formed. Among them, the high-pressure plugging slurry is composed of plugging materials of different particle sizes, types, and strengths, which can form a high-strength plugging layer, thereby improving the pressure-bearing capacity of the formation. The pressure-bearing capacity of the plugging layer formed by the high-pressure plugging slurry is evaluated in combination with the pressure-bearing capacity evaluation method, which can better achieve a true simulation of the underground situation. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Attached Figure 1 This is a schematic diagram of an enlarged top view of the 3D printed artificial core structure of an embodiment of the present invention.

[0018] Attached Figure 2 It is a schematic diagram of the main structure of the existing leak plugging instrument.

[0019] Attached Figure 3 It is a cross-sectional enlarged structural schematic diagram of the reverse discharge device.

[0020] The codes in the accompanying drawings are: 1 is a 3D printed splicing block for fixing the crack width of the upper core, 2 is a 3D printed splicing block for fixing the crack width of the lower core, 3 is a high temperature resistant core sleeve, 4 is a cup seat, 5 is a base, 6 is a handle, 7 is a sleeve, 8 is a pressure divider, 9 is a screw cover, 10 is a support tube, 11 is a fastening handle, 12 is a connecting valve stem, 13 is a three-way assembly, 14 is an air source end cover, 15 is a ball valve, 16 is a marble bed tube, 17 is a faucet joint, 18 is a core clamp, 19 is a connecting nut, 20 is an output joint A, 21 is an air source valve, 22 is an output joint B, 23 is an output nut, and in is the spacing. DETAILED DESCRIPTION

[0021] The present invention is not limited by the following embodiments, and specific implementation methods can be determined based on the technical solution of the present invention and actual conditions.

[0022] In the present invention, for the convenience of description, the relative position relationship of each component is described according to the attached Figure 1 The layout is described in detail, such as the positional relationship of front, back, top, bottom, left, right, etc., which is based on the attached manual. Figure 1 The layout direction is determined by the

[0023] If the specific conditions are not specified in the examples, the experiments were carried out under conventional conditions or conditions recommended by the manufacturer. If the manufacturers of the reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0024] As attached Figure 1As shown, the present invention provides a 3D printed artificial rock core, comprising a rock core assembly and a high temperature resistant rock core sleeve (3), wherein the rock core assembly comprises a 3D printed splicing block (1) for fixing the crack width of the upper part of the rock core and a 3D printed splicing block (2) for fixing the crack width of the lower part of the rock core; wherein the 3D printed splicing block (1) for fixing the crack width of the upper part of the rock core, the 3D printed splicing block (2) for fixing the crack width of the lower part of the rock core and the high temperature resistant rock core sleeve (3) are assembled together to form a cylinder; one side of the 3D printed splicing block (1) for fixing the crack width of the upper part of the rock core and one side of the 3D printed splicing block (2) for fixing the crack width of the lower part of the rock core are both arranged to simulate the rough surface of the rock, and the concave and convex parts of the rough surfaces of the two opposite sides are correspondingly fitted together, and assembled together to form a cylinder, and the high temperature resistant rock core sleeve (3) is wrapped around the outside of the rock core to fix the rock core into a cylinder, so that a spacing is left between the opposite surfaces of the 3D printed splicing block (1) for fixing the crack width of the upper part of the rock core and the 3D printed splicing block (2) for fixing the crack width of the lower part of the rock core.

[0025] The 3D printed cores simulating fractured leakage formations can be reused to evaluate the pressure bearing capacity of the plugging layer of the plugging slurry.

[0026] The present invention improves the existing QD-2 type leak plugging instrument (such as the attached Figure 2 The core holder 18 (as shown in the attached Figure 3 The inner diameter of the core holder 18 is set to 45.1 mm to install the 3D printed artificial core. The operation method of the QD-2 plugging instrument refers to the operating procedures of the QD-2 plugging material test instrument.

[0027] The present invention provides a pressure-bearing plugging slurry, which comprises, by weight, 100 parts of water, 2 to 8 parts of fine walnut shells, 2 to 6 parts of plant fibers, 15 to 25 parts of inorganic rigid particles, and 2 to 6 parts of gel; the plant fiber particle size is 0.15 mm to 0.28 mm; The particle size of the fine walnut shell powder is 0.42 mm to 0.85 mm; the inorganic rigid particles include inorganic rigid particles I with a particle size of 0.45 mm to 2 mm, inorganic rigid particles II with a particle size of 0.28 mm to 0.9 mm, inorganic rigid particles III with a particle size of 0.18 mm to 0.45 mm, and inorganic rigid particles IV with a particle size of 0.15 mm to 0.28 mm; the gel is ZND-2 gel. The inorganic rigid particle material is marble.

[0028] The present invention will be further described below in conjunction with embodiments: Example 1 The specific preparation method of high pressure plugging slurry is as follows: Under stirring conditions, 100 parts by weight of water, 5 parts by weight of fine walnut shells, 4 parts by weight of plant fibers, 20 parts by weight of inorganic rigid particles, and 4 parts by weight of gel are sequentially added to 100 parts by weight of water to obtain a high-pressure plugging slurry A1 for use in vicious leakage formations.

[0029] The inorganic rigid particles include inorganic rigid particles I with a particle size of 0.45 mm to 2 mm, inorganic rigid particles II with a particle size of 0.28 mm to 0.9 mm, inorganic rigid particles III with a particle size of 0.18 mm to 0.45 mm, and inorganic rigid particles IV with a particle size of 0.15 mm to 0.28 mm; the weight ratio of the inorganic rigid particles I, the inorganic rigid particles II, the inorganic rigid particles III, and the inorganic rigid particles IV is 1:1:1:1. Subsequent Examples 2 to 3 use inorganic rigid particles of the same specifications.

[0030] Example 2 The specific preparation method of high pressure plugging slurry is as follows: Under stirring conditions, 100 parts by weight of water, 8 parts by weight of fine walnut shells, 6 parts by weight of plant fibers, 25 parts by weight of inorganic rigid particles, and 6 parts by weight of gel are sequentially added to 100 parts by weight of water to obtain a high-pressure plugging slurry A2 for use in vicious leakage formations.

[0031] Example 3 The specific preparation method of high pressure plugging slurry is as follows: Under stirring conditions, 100 parts by weight of water, 2 parts by weight of fine walnut shells, 2 parts by weight of plant fibers, 15 parts by weight of inorganic rigid particles, and 2 parts by weight of gel are sequentially added to 100 parts by weight of water to obtain a high-pressure plugging slurry A3 for use in vicious leakage formations.

[0032] Comparative Example 1 The remaining features are the same as those of Example 1, except that the amount of inorganic rigid particles added is 0 parts by weight, and plugging slurry D1 is obtained.

[0033] Comparative Example 2 The remaining characteristics are the same as those of Example 1, except that the amount of fine walnut shell added is 0 parts by weight, and plugging slurry D2 is obtained.

[0034] Comparative Example 3 The remaining features are the same as those of Example 1, except that the amount of plant fiber added is 0 parts by weight, and plugging slurry D3 is obtained.

[0035] Leakage plugging performance evaluation experiment: The improved QD-2 plugging instrument was used to test the plugging performance of the plugging slurries obtained in the above embodiments and comparative examples. The specific experimental steps are as follows: Step 1: Before the experiment, the core components of the 3D printed artificial core (the spacing between the opposite surfaces of the 3D printed splicing block (1) for fixing the crack width of the upper part of the core and the 3D printed splicing block (2) for fixing the crack width of the lower part of the core is 4 mm) are assembled and buckled to form a core, and a high-temperature resistant core sleeve (3) is wrapped around the outside of the core to fix the core into a cylindrical shape, ensuring that each core component will not be scattered during the process of being placed in the core holder 18 of the plugging instrument, and then placed in the core holder 18; Step 2: Inject the prepared drilling fluid containing high-pressure plugging slurry into the sleeve 7 of the plugging instrument, and the drilling fluid in the sleeve passes through the ball valve 15 and the core holder 18 of the reverse flow device in sequence; Step 3: Adjust the pressure in the sleeve 7 of the plugging instrument and the connected structure, and increase the pressure value from low to high with a starting pressure of 0.5 MPa. After the pressure of the drilling fluid in the sleeve 7 reaches a certain value, it will pass through the 3D printed artificial core and be discharged into the collection tube through the output connector B 22; the single increase value is 0.5 MPa and the pressure is stabilized for 2 minutes and the volume of the discharged drilling fluid is recorded. When the volume of the discharged drilling fluid suddenly increases, the highest pressure value before the discharge is recorded; Step 4: After recording the maximum breakthrough pressure of the drilling fluid and the leakage volume for a certain period of time, close the connecting valve stem 12, close the gas supply source and release the pressure. The experimental data is shown in Table 1.

[0036] From the data in Table 1, we can see that: (1) The pressure bearing effect of the plugging layer of the high-pressure plugging slurry in Examples 1 to 3 is A1>A2>A3, and the plugging layer of A1 has the best pressure bearing effect of 10 MPa; (2) The pressure bearing effect of the plugging layer of the plugging slurry in Comparative Examples 1-3 is D1<D2=D3, and the plugging layer of D1 has the best pressure bearing effect of 4MPa; In summary, the pressure-bearing effect of the high-pressure plugging slurry plugging layer provided in the embodiments is greater than the pressure-bearing effect of the plugging layer of the comparison plugging slurry. Among them, the plugging layer of the A1 plugging slurry has the best pressure-bearing effect of 10 MPa, indicating that the plugging slurry composed of plugging materials of different particle sizes, types and strengths can form a high-strength plugging layer, thereby improving the pressure-bearing capacity of the formation.

[0037] The above technical features constitute the embodiments of the present invention, which have strong adaptability and implementation effect. Non-essential technical features can be added or reduced according to actual needs to meet the requirements of different situations.

Claims

1. A high pressure plugging slurry, characterized in that The composition comprises, by weight, 100 parts of water, 2 to 8 parts of fine walnut shells, 2 to 6 parts of plant fibers, 15 to 25 parts of inorganic rigid particles, and 2 to 6 parts of gel; The plant fiber particle size is 0.15 mm to 0.28 mm; The particle size of the fine walnut shell powder is 0.42 mm to 0.85 mm; The inorganic rigid particles include inorganic rigid particles I with a particle size of 0.45 mm to 2 mm, inorganic rigid particles II with a particle size of 0.28 mm to 0.9 mm, inorganic rigid particles III with a particle size of 0.18 mm to 0.45 mm, and inorganic rigid particles IV with a particle size of 0.15 mm to 0.28 mm; The gel is ZND-2 gel.

2. The high pressure plugging slurry according to claim 1, characterized in that The inorganic rigid particle material is marble.

3. The high pressure plugging slurry according to claim 1 or 2, characterized in that The weight ratio of the inorganic rigid particles I, the inorganic rigid particles II, the inorganic rigid particles III and the inorganic rigid particles IV is 1:1:1:

1.

4. The high pressure plugging slurry according to claim 1, characterized in that The method is as follows: gel, fine walnut shells, plant fibers and inorganic rigid particles are sequentially added to water under stirring to obtain a high-pressure plugging slurry.

5. A 3D printed artificial rock core, characterized in that The invention comprises a core assembly and a high temperature resistant core sleeve (3), wherein the core assembly comprises a 3D printed splicing block (1) for fixing the crack width of the upper part of the core and a 3D printed splicing block (2) for fixing the crack width of the lower part of the core; wherein the 3D printed splicing block (1) for fixing the crack width of the upper part of the core, the 3D printed splicing block (2) for fixing the crack width of the lower part of the core and the high temperature resistant core sleeve (3) are assembled together to form a cylinder; one side of the 3D printed splicing block (1) for fixing the crack width of the upper part of the core and one side of the 3D printed splicing block (2) for fixing the crack width of the lower part of the core are both arranged to simulate the rough surface of the rock, and the concave and convex parts of the rough surfaces of the two opposite sides are correspondingly fitted together, and assembled together to form a cylinder; the high temperature resistant core sleeve (3) is wrapped around the outside of the core to fix the core into a cylinder, so that a distance is left between the opposite surfaces of the 3D printed splicing block (1) for fixing the crack width of the upper part of the core and the 3D printed splicing block (2) for fixing the crack width of the lower part of the core.

6. The 3D printed artificial core according to claim 5, characterized in that The 3D printed splicing block (1) for fixing the width of the upper crack of the core, the 3D printed splicing block (2) for fixing the width of the lower crack of the core, and the high temperature resistant core sleeve (3) all use 3D printing materials, and the 3D printing materials are high temperature resistant soluble resins; or / and, the 3D printer used by the 3D printed splicing block (1) for fixing the width of the upper crack of the core, the 3D printed splicing block (2) for fixing the width of the lower crack of the core, and the high temperature resistant core sleeve (3) is a light-curing 3D printer FARSOON HT251P.

7. The 3D printed artificial core according to claim 5 or 6, characterized in that The lengths of the 3D printed splicing block (1) for fixing the crack width of the upper core, the 3D printed splicing block (2) for fixing the crack width of the lower core, and the high temperature resistant core sleeve (3) are all 55 mm, and the cross-sectional diameter of the cylinder spliced ​​by the 3D printing is 44 mm; the outer diameter of the high temperature resistant core sleeve (3) is 45 mm, and the inner diameter is 44 mm.

8. The 3D printed artificial core according to claim 7, characterized in that The spacing between the opposing surfaces of the 3D printed splicing block (1) for fixing the crack width of the upper core and the 3D printed splicing block (2) for fixing the crack width of the lower core is 1 mm to 5 mm.

9. A method for evaluating the pressure bearing capacity of a 3D printed artificial core using the high pressure plugging slurry according to any one of claims 1 to 4, characterized in that The 3D printed artificial core is the 3D printed artificial core according to any one of claims 5 to 7; the pressure bearing capacity evaluation method is performed according to the following steps: Step 1: Before the experiment, the core components of the 3D printed artificial core are assembled and buckled to form a core, and a high-temperature resistant core sleeve (3) is wrapped around the outside of the core to fix the core into a cylindrical shape, ensuring that each core component will not be scattered during the process of being placed in the core holder of the plugging instrument, and then placed in the core holder; Step 2: Inject the prepared drilling fluid containing high-pressure plugging slurry into the sleeve of the plugging instrument, and the drilling fluid in the sleeve passes through the ball valve and core holder of the reverse flow device in sequence; Step 3: Adjust the pressure in the sleeve of the plugging instrument and the connected structure, and increase the pressure value from low to high with a starting pressure of 0.5 MPa. After the pressure in the sleeve reaches a certain value, the drilling fluid will pass through the 3D printed artificial core and be discharged into the collection tube; the single increase value is 0.5 MPa and the pressure is maintained for 2 minutes and the volume of the discharged drilling fluid is recorded. When the volume of the discharged drilling fluid suddenly increases, the highest pressure value before the discharge is recorded; Step 4: After recording the maximum breakthrough pressure of the drilling fluid and the leakage volume over a certain period of time, close the connecting valve stem, turn off the gas supply and release the pressure.

10. The pressure bearing capacity evaluation method based on 3D printing artificial core according to claim 7, characterized in that The inner diameter of the core holder of the reverse discharge device of the plugging instrument is 45.1mm.

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