Shaft reconstruction method combining expansion pipe subsidy and narrow gap well cementation

Abstract

The invention discloses a shaft reconstruction method combining expansion pipe patching and narrow-gap well cementation, and relates to the technical field of reservoir transformation. According to the shaft reconstruction method, strong and weak gel and thermosetting resin are used for blocking primary fracturing cracks and cement sheaths poor in well cementation quality, water breakthrough cracks are effectively blocked, the well cementation quality is improved, and the well cementation efficiency is improved. After the expansion pipe is pressed and expanded, a shaft with a larger size (106mm) is obtained, so that later multi-round repeated fracturing and underground operation are facilitated; a complete and clean new shaft is formed, the well cementation quality is improved, the efficiency of inter-section partial pressure is effectively improved, and subdivision cutting volume fracturing of an old horizontal well is achieved; the requirements of large displacement, large sand amount and large liquid amount fracturing in repeated transformation of the horizontal well can be met, the construction displacement is larger than or equal to 14 m < 3 > / min, and the fracturing efficiency is larger than or equal to 2 sections per day; the expansion pipe, the gel, the resin and other materials are used for effectively plugging water breakthrough cracks, and the mechanical and chemical double water plugging effect is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of reservoir reconstruction, and particularly to a wellbore reconstruction method combining expandable tube patch and narrow-gap cementing. Background Art

[0002] With the continuous extension of production time, the ultra-low permeability Class II and Class III oil reservoirs in Changqing Oilfield are characterized by poor reservoir physical properties and well-developed natural fractures. It is difficult to establish a water injection displacement system, and they generally face problems such as low production and water breakthrough. In recent years, for low-production horizontal wells, aiming at volume fracturing, a large-displacement double-packer single-slotted staged fracturing technology integrating "comprehensive energy supplementation, dynamic temporary plugging, and synchronous fracturing" has been formed, but there are problems such as long construction period and high construction operation costs. Horizontal well volume refracturing is a key technology for tapping the remaining oil in old oilfields, improving oil recovery and production rate. To meet the requirements of horizontal well repeated and efficient staged fracturing process tests, it is necessary to carry out research on key tools and processes for horizontal wellbore reconstruction.

[0003] In the existing horizontal wellbore reconstruction schemes, the following problems exist:

[0004] (1) In chemical plugging wellbore reconstruction, it is difficult to accurately plug each perforation section, the overall pressure-bearing capacity of the wellbore is low, and serious leakage occurs in individual sections, making it difficult to meet the subsequent bridge-perforation combined fracturing;

[0005] (2) In small-casing cementing wellbore reconstruction, the original casing is reduced in diameter, and the wellbore is opened to 94 mm, which cannot meet the requirements of multiple rounds of volume refracturing in the later stage.

[0006] (3) In expandable tube patch wellbore reconstruction, the sealing ring is prone to wear and failure, and it cannot plug the outside-the-tube channeling and water-seeing fractures. Summary of the Invention

[0007] The purpose of the present invention is to provide a wellbore reconstruction method combining expandable tube patch and narrow-gap cementing, which effectively solves the problems of small wellbore size in small-casing cementing and poor inter-stage separation sealing performance in expandable tube patch wellbore reconstruction. By organically combining the two technologies and making the best use of their advantages and avoiding their disadvantages, a new wellbore with large through-diameter and good inter-stage sealing is formed. To achieve the above purpose, the present invention provides the following technical solutions:

[0008] The present invention provides a wellbore reconstruction method combining expandable tube patch and narrow-gap cementing, and the method includes the following steps:

[0009] Step S1: Inject displacement fluid into the formation until the formation pressure recovery level reaches 100%;

[0010] Step S2: Inject weak gel and strong gel into the primary fracturing cracks, shut in the well and wait for setting. The weak gel and strong gel solidify under the formation temperature and pressure conditions.

[0011] Step S3: After processing the wellbore, lower the simulated wellbore cleaning string to the artificial bottom hole to ensure that the wellbore has no deformation and foreign objects. Displace a wellbore volume of metal drag reduction fluid and then pull out the simulated wellbore cleaning string.

[0012] Step S4: Lower the expandable casing cementing string to the artificial bottom hole, circulate to wash out the metal drag reduction fluid and the oil and gas mixture in the wellbore. First, inject the guar gum base fluid, then inject the thermosetting resin, drop a small rubber plug, and displace with clear water until the small rubber plug reaches and coincides with the hollow rubber plug in the expandable hanger to form a composite rubber plug. Increase the pressure by ≥5 MPa, cut the shear pin, continue to displace the composite rubber plug until it touches the pressure ball seat and generates a touch pressure. It is required that the touch pressure ≥20 MPa to complete the cementing.

[0013] Step S5: After successful touch pressure, continue to apply pressure to 45 MPa. The expandable casing and the expandable hanger are simultaneously stressed and expanded to form a new wellbore with a large diameter. Pull out the drill pipe above the hanger and shut in the well for 72 h of waiting for setting.

[0014] Step S6: Conduct drilling and grinding treatment on the new wellbore of the horizontal well to remove the residual thermosetting resin in the wellbore and conduct flushing to ensure the wellbore is unobstructed.

[0015] Further, in Step S1, the formula of the oil displacement fluid is petroleum sulfonate oil displacement agent with a concentration of 3.0 kg / m 3 + clear water, and the interfacial tension of the oil displacement agent < 1×10 -3 mN / m.

[0016] Further, in Step S2, the gel is a polyacrylamide polymer modified by tetramethylethylenediamine (TMEDA), with a visual density of 1.56 tons / cubic meter, a weak gel concentration of 0.2%, a strong gel concentration of 0.3%, a weak gel viscosity ≥8000 mPa·s, a strong gel viscosity ≥20000 mPa·s, and the displacement rate for lost circulation prevention construction is 0.5 - 0.7 m 3 / min, and the construction pressure ≤20 MPa.

[0017] Further, in Step S3, the simulated wellbore cleaning string is a Φ108mm×Φ70mm guide cone + Φ108mm expandable casing × 3 roots + a coupling nipple + Φ73mm right-hand drill pipe.

[0018] Further, in Step S4, the expandable casing cementing string structure is a Φ108mm guide shoe + Φ108mm spring-type float collar + Φ108mm ball-type float collar + Φ108mm spring-type float collar + Φ108mm pressure ball seat + Φ108mm expandable casing + Φ108mm expandable casing positioning nipple × 1 root + Φ108mm expandable casing + Φ108mm casing positioning nipple × 1 root + Φ108mm expandable casing + Φ108mm coupling nipple + expandable cementing hanger + coupling nipple + Φ73mm right-hand drill pipe.

[0019] Further, the outer diameter of the expandable tube before expansion is 108 mm, the inner diameter is 94 mm, the outer diameter after expansion is 120 mm, the inner diameter is 106 mm, the internal pressure resistance is ≥ 75 MPa, and the external pressure resistance is ≥ 45 MPa.

[0020] Further, in step S4, the viscosity of the thermosetting resin is ≤ 100 mPa·s, the density is ≤ 1.25 g / cm 3 , the initial setting time is ≥ 6 h, and the compressive strength is ≥ 75 MPa.

[0021] Further, in step S4, the designed injection volume of the guar gum base fluid is 4 m 3 , and the mass concentration is 0.5%; the designed injection volume of the thermosetting resin is twice the annular volume between the expandable tube before expansion and the 5 1 / 2-inch wellbore.

[0022] Further, in step S5, after successful pressure bumping, continue to pump to 45 MPa, keep the pressure stable for 30 min to complete the expansion of the expandable tube, and lift the Φ73 mm regular right-hand drill pipe by 2 m to complete the expansion of the expansion hanger.

[0023] Further, in step S6, lower the Φ73 mm tool tubing + flat-bottom mill, drill out the remaining plug surface in the pipe string, then lower the Φ73 mm tool tubing + Φ100 mm hole opener to the position of the pressure holding ball seat for hole opening, reverse circulate to wash the well until the wellbore is clean, and then pull out the hole opening pipe string.

[0024] The technical effects and advantages of the present invention:

[0025] (1) The present invention uses strong and weak gels and thermosetting resins to plug the primary fracturing fractures and the cement sheath with poor cementing quality, effectively plugs the water-producing fractures, and improves the cementing quality. After the expandable tube is expanded by pumping, a wellbore with a larger size (106 mm) is obtained, which is convenient for subsequent multi-round repeated fracturing and downhole operations.

[0026] (2) The present invention forms a complete and clean new wellbore, improves the cementing quality, effectively improves the effective rate of sectional pressure splitting, and enables the old horizontal wells to achieve fine-cut volume fracturing.

[0027] (3) The present invention can meet the requirements of large displacement, large sand volume, and large liquid volume fracturing for repeated transformation of horizontal wells, with the construction displacement ≥ 14 m 3 / min and the fracturing efficiency ≥ 2 sections / day.

[0028] (4) The present invention effectively plugs the water-producing fractures by using materials such as expandable tubes, gels, and resins, realizing the dual water plugging effect of "mechanical + chemical".

[0029] Other features and advantages of the present invention will be described in the following description, and partly become obvious from the description, or be understood by implementing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0031] Figure 1 This is a structural diagram of a wellbore reconstruction string combining an expandable pipe patch and narrow gap cementing according to the present invention. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] The design concept of the present invention is: through pre-fracturing energy replenishment and crack leakage reduction, an expansion pipe and cementing accessories are lowered into a 5.5-inch wellbore, and low-viscosity high-strength resin is injected to complete cementing. Further pressure expansion causes the expansion pipe to expand as a whole to increase the inner diameter, and a portion of the resin in the narrow gap is squeezed into the initial fracturing cracks and the cement ring with poor cementing quality, thereby blocking the initial fracturing cracks and improving the original cementing quality. After closing the well and waiting for solidification, a complete new wellbore is formed, and the bridge-shot combined fracturing process can be applied to greatly improve the fracturing construction efficiency and transformation effect.

[0034] To achieve the above object, the present invention discloses a wellbore reconstruction method combining expansion tube patching with narrow gap cementing, comprising the following steps:

[0035] Step S1, replenishing the formation energy, injecting oil displacement fluid into the formation until the formation pressure is maintained at a level restored to 100%;

[0036] Step S2, injecting weak gel and strong gel into the primary fracturing fracture, shutting down the well and waiting for solidification, the weak gel and strong gel solidify under the formation temperature and pressure conditions, reaching a certain viscosity to form a soft barrier, thereby reducing fracture leakage;

[0037] Step S3: After processing the wellbore, lower the simulated wellbore cleaning string to the artificial bottom hole to ensure that there is no deformation or foreign matter in the wellbore, displace one wellbore volume of metal drag reduction fluid, and pull out the simulated wellbore cleaning string;

[0038] Step S4: Lower the expandable casing cementing string to the artificial bottom hole, circulate to wash out the metal drag reduction fluid and the oil and gas mixture in the wellbore. First, inject 4 m 3 of guar gum base fluid with a concentration of 0.5%, then inject the designed amount of heat-setting resin, drop a small rubber plug, and displace it with clear water until the small rubber plug reaches and coincides with the hollow rubber plug in the expandable hanger to form a composite rubber plug. The pressure rises by ≥5 MPa, cut the shear pin, continue to displace the composite rubber plug until it hits the pressure ball seat and the pressure bump is achieved. It is required that the pressure bump is ≥20 MPa to complete the cementing;

[0039] Step S5: After successful pressure bump, continue to apply pressure to 45 MPa, and the expandable pipe and the expandable hanger are simultaneously stressed and expanded to form a new wellbore with a large diameter. Pull out the Φ73 mm drill pipe, shut in the well and wait for setting for 72 h;

[0040] Step S6: Carry out drilling and grinding treatment on the new wellbore of the horizontal well to remove the residual heat-setting resin in the wellbore and wash the well to ensure the wellbore is unobstructed.

[0041] A further improvement of the present invention is that in step S1, the amount of oil displacement fluid injected into the formation is calculated according to the current formation pressure maintenance level of the well, and the amount of fluid required to restore the formation pressure maintenance level to 100% is calculated based on the material balance equation. The formula of the oil displacement fluid is petroleum sulfonate oil displacement agent with a concentration of 3.0 kg / m 3 + clear water, and the interfacial tension of the oil displacement agent is <1×10 - 3 mN / m.

[0042] A further improvement of the present invention is that in step S2, the gel is a polyacrylamide polymer modified with tetramethylethylenediamine (TMEDA), with an apparent density of 1.56 tons / cubic meter, the viscosity of the weak gel is ≥8000 mPa·s, the viscosity of the strong gel is ≥20000 mPa·s, and the displacement construction flow rate for lost circulation control is 0.5 - 0.7 m 3 / min, and the construction pressure ≤20 MPa.

[0043] A further improvement of the present invention is that in step S3, the simulated wellbore cleaning string is a Φ108 mm×Φ70 mm guide cone + Φ108 mm expandable pipe×3 roots + a variable coupling short joint + Φ73 mm NC drill pipe.

[0044] A further improvement of the present invention is that in step S4, the expandable casing string structure is Φ108mm guide shoe + Φ108mm float collar (spring type) + Φ108mm float collar (float ball type) + Φ108mm float collar (spring type) + Φ108mm bump pressure ball seat + Φ108mm expandable casing + Φ108mm expandable casing positioning short joint × 1 piece + Φ108mm expandable casing + Φ108mm casing positioning short joint × 1 piece + Φ108mm expandable casing + Φ108mm reducer short joint + expandable cementing hanger + reducer short joint + Φ73mm NC drill pipe (such as Figure 1 ). Before expansion, the outer diameter of the expandable casing is 108mm, the inner diameter is 94mm. After expansion, the outer diameter is 120mm, the inner diameter is 106mm, the internal pressure resistance is ≥75MPa, and the external pressure resistance is ≥45MPa. The retrievable hanger is an expandable retrievable hanger, and its size and performance are consistent with those of the expandable casing. The position of the hanger is within 10m above and below the build point. After drilling to the bottom and circulating 2 wellbore volumes, rotate the drill string 20 turns, release the hanger and lift it by 1.2m. After verifying the successful release, lower it to the original suspended weight and start cementing. The viscosity of the thermosetting resin is ≤100mPa.s, the density is ≤1.25g / cm 3 , the initial setting time is ≥6h, and the compressive strength is ≥75MPa. The designed injection volume of the resin is twice the annulus volume between the expandable casing before expansion and the 5.5-inch wellbore.

[0045] A further improvement of the present invention is that in step S5, after successful bump pressure, continue to pump to 45MPa and keep the pressure stable for 30min to complete the expansion of the expandable casing, and lift the Φ73mm NC drill pipe to complete the expansion of the expansion hanger.

[0046] A further improvement of the present invention is that in step S6, lower the Φ73mm work string + flat bottom mill, drill the remaining plug surface in the pipe string, then lower the Φ73mm work string + Φ100mm hole opener to the position of the pressure holding ball seat for hole opening, reverse circulate to wash the well until the wellbore is clean, and then pull out the hole opening string.

[0047] Embodiment

[0048] The specific implementation case includes the following steps:

[0049] Step S1: Supplement the formation energy by injecting 2000 cubic meters of oil displacement fluid into the formation until the formation pressure recovery level reaches 100%;

[0050] Step S2: Inject 300 cubic meters of weak gel and 200 cubic meters of strong gel into the primary fracture, shut in the well and wait for setting. The weak gel and strong gel solidify under the formation temperature and pressure conditions, reach a certain viscosity to form a soft barrier, and reduce fracture leakage;

[0051] Step S3: After processing the wellbore, lower the simulated wellbore cleaning string to the artificial bottom hole to ensure that the wellbore has no deformation and foreign objects. Displace a wellbore volume of metal drag reduction fluid and then pull out the simulated wellbore cleaning string;

[0052] Step S4: Lower the expandable casing cementing string to the artificial bottom hole, circulate to wash out the metal drag reduction fluid and the oil-gas mixture in the wellbore, inject 6.2 cubic meters of hot-setting resin, drop a small rubber plug, displace with clear water until the small rubber plug reaches and coincides with the hollow rubber plug in the expandable hanger to form a composite rubber plug. Increase the pressure by 7 MPa to shear the shear pin, continue to displace the composite rubber plug until it reaches the bump pressure seat for bump pressure. The bump pressure is 27 MPa to complete the cementing;

[0053] Step S6: After successful bump pressure, continue to apply pressure to 45 MPa. The expandable pipe and the expandable hanger are simultaneously stressed and expanded to form a new wellbore with a large diameter. Pull out the Φ73 mm drill pipe and shut in the well for 72 h for setting;

[0054] Step S6: Carry out drilling and grinding treatment on the new wellbore of the horizontal well to remove the residual hot-setting resin in the wellbore and conduct through-washing to ensure the wellbore is unobstructed.

[0055] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A wellbore reconstruction method combining expandable tubular patch and narrow-gap cementing, characterized in that, The method includes the following steps: Step S1: Inject displacement fluid into the formation until the formation pressure recovery level reaches 100%; Step S2: Inject weak gel and strong gel into the primary fracture, shut in the well and wait for gelation. The weak gel and strong gel solidify under the formation temperature and pressure conditions; Step S3: After treating the wellbore, run in a simulated wellbore cleaning string to the artificial bottom hole to ensure that there is no deformation or foreign matter in the wellbore. Displace one wellbore volume of metal drag reduction fluid, and pull out the simulated wellbore cleaning string; Step S4: Run in an expandable casing cementing string to the artificial bottom hole, circulate to wash out the metal drag reduction fluid and the oil and gas mixture in the wellbore. First inject guar gum base fluid, then inject thermosetting resin, drop a small rubber plug, displace the small rubber plug with clean water until it coincides with the hollow rubber plug in the expandable hanger to form a composite rubber plug. Increase the pressure by ≥5MPa, cut the shear pin, continue to displace the composite rubber plug until it hits the pressure bump seat and the pressure bump is ≥20MPa to complete cementing; Step S5: Continue to apply pressure up to 45MPa, and the expandable casing and the expandable hanger expand simultaneously to form a new wellbore with a large diameter. Pull out the drill pipe above the hanger and shut in the well to wait for gelation; Step S6: Carry out drilling and grinding treatment on the new wellbore of the horizontal well to remove the residual thermosetting resin in the wellbore and conduct through-washing to ensure the wellbore is unobstructed; 2. The wellbore reconstruction method combining expandable tube patch and narrow-gap cementing according to claim 1, wherein, In step S1, the formulation of the oil-displacing fluid is petroleum sulfonate oil-displacing agent with a concentration of 3.0 kg / m 3 + fresh water, and the interfacial tension of the oil-displacing agent is < 1×10 -3 mN / m.

3. A wellbore reconstruction method combining expandable-tube patch and narrow-gap cementing according to claim 1 or 2, characterized in that, In step S2, the gel is a tetramethylethylenediamine (TMEDA)-modified polyacrylamide polymer, with a bulk density of 1.56 tons / cubic meter, a weak gel concentration of 0.2%, a strong gel concentration of 0.3%, a weak gel viscosity ≥ 8000 mPa.s, a strong gel viscosity ≥ 20000 mPa.s, and a lost circulation control construction displacement of 0.5 - 0.7 m 3 / min, and the construction pressure ≤ 20 MPa.

4. A wellbore reconstruction method combining expandable tube patch and narrow-gap cementing according to claim 2, characterized in that, In Step S3, the simulated wellbore cleaning string is a Φ108mm×Φ70mm guide cone + Φ108mm expandable casing × 3 pieces + a variable-coupling short joint + Φ73mm NC drill pipe; 5. A wellbore reconstruction method combining expandable tubular patch and narrow-gap cementing according to claim 1, characterized in that, In Step S4, the expandable casing cementing string structure is a Φ108mm guide shoe + Φ108mm spring-type float collar + Φ108mm ball-type float collar + Φ108mm spring-type float collar + Φ108mm pressure bump seat + Φ108mm expandable casing + Φ108mm expandable casing positioning short joint × 1 piece + Φ108mm expandable casing + Φ108mm casing positioning short joint × 1 piece + Φ108mm expandable casing + Φ108mm variable-coupling short joint + expandable cementing hanger + variable-coupling short joint + Φ73mm NC drill pipe; 6. A wellbore reconstruction method combining expandable tube patch and narrow annulus cementing according to claim 5, characterized in that The outer diameter of the expandable casing before expansion is 108mm, the inner diameter is 94mm, the outer diameter after expansion is 120mm, the inner diameter is 106mm, the internal pressure resistance is ≥75MPa, and the external pressure resistance is ≥45MPa; 7. A wellbore reconstruction method combining expandable tube patch and narrow annulus cementing according to claim 1, 2 or 5, characterized in that In step S4, the viscosity of the thermosetting resin is ≤ 100 mPa·s, the density is ≤ 1.25 g / cm 3 , the initial setting time is ≥ 6 h, and the compressive strength is ≥ 75 MPa.

8. A wellbore reconstruction method combining expandable tube patch and narrow annulus cementing according to claim 1, characterized in that In step S4, the designed injection volume of the guar gum base fluid is 4 m 3 , and the mass concentration is 0.5%; the designed injection volume of the thermosetting resin is twice the annulus volume between the expanded liner and the 5.5-inch wellbore before the liner expansion.

9. A wellbore reconstruction method combining expandable tube patch and narrow annulus cementing according to claim 1, characterized in that, In Step S5, after successful pressure bump, continue to apply pressure up to 45MPa, keep the pressure stable for 30min to complete the expansion of the expandable casing, and lift the Φ73mm NC drill pipe by 2m to complete the expansion of the expandable hanger; 10. A wellbore reconstruction method combining expandable tube patch and narrow annulus cementing as claimed in claim 1, characterized in that, In Step S6, run in a Φ73mm tool tubing + flat-bottomed milling shoe, drill out the remaining plug surface in the string, then run in a Φ73mm tool tubing + Φ100mm wellbore cleaning gauge to the position of the pressure bump seat for wellbore cleaning. Conduct reverse circulation washing until the wellbore is clean, and pull out the wellbore cleaning string.

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