A fracturing method for adjusting and plugging cracks of an oil well

Abstract

The present application relates to oil and gas field production development technical field, disclose a kind of " adjust - block " fracturing method of oil well fracture, the method comprises: introducing water plugging material and displacement fluid to the target zone of target well, soak well;The water plugging material includes polymer gel, body swelling particle and resin sand.The " adjust - block " fracturing method of oil well fracture of the present application, in combination with the concept of water well profile control, at the end of oil well, it can be " adjusted " - polymer gel adjusts water line, and it can be " blocked " - absorbs water and blocks the original high-permeability water line channel and most artificial fractures, and by introducing displacement fluid to leave oil discharge channel, so as to continue production to tap remaining oil, realize the purpose of reducing liquid and increasing oil, while ensuring long-term effectiveness of water plugging.

Description

Technical Field

[0001] This invention relates to the field of oil and gas field production and development technology, specifically to a fracturing method for "adjustment-plugging" fractures in oil wells. Background Technology

[0002] Hydraulic fracturing technology is a widely used production enhancement measure in major oilfields both domestically and internationally. During oilfield development, water injection from wells is primarily used to displace crude oil and replenish formation energy. However, as development time increases, most oilfields enter the mid-to-late stages of development, facing increasingly severe extraction difficulties and deteriorating reservoir properties. To fully revitalize the reservoir, the scale of fracturing increases, and fracture propagation easily leads to cross-contamination with the effective injection wells. Serious problems such as water flooding and water channeling caused by fracturing gradually become prominent, resulting in ineffective water circulation, reduced crude oil recovery, and impacting oilfield production and profitability. In recent years, commonly used water shut-off methods for high water-cut reservoirs include mechanical, physical, and chemical methods. Packer mechanical water shut-off or cementing physical water shut-off completely seals the high water-cut layers, achieving good water shut-off effects but preventing continued production of that layer. Chemical water shut-off only blocks the near-wellbore area, failing to achieve fluid flow diversion or displacement of lateral residual oil. Therefore, it is necessary to study a new fracturing method that can effectively seal fractures to reduce water cut and improve crude oil recovery and production efficiency. Summary of the Invention

[0003] The purpose of this invention is to overcome the problems of increased fracturing scale, water flooding and water channeling caused by fracture expansion, and reduced oil recovery rate in existing technologies. This invention provides a "modulation-plugging" fracturing method for oil well fractures. This method combines the concept of water well profile modification and water plugging fracturing technology, and has the advantages of effectively plugging fractures and increasing production and efficiency.

[0004] To achieve the above objectives, the present invention provides a fracturing method for "adjustment-plugging" fractures in oil wells, the method comprising: introducing water-plugging material and displacement fluid into the target section of the target well, and simmering the well; the water-plugging material includes polymer gel, bulk-swelling particles and resin sand.

[0005] The "adjustment-plugging" fracturing method for oil well fractures of the present invention can both "adjust" the waterline by using polymer gel at the oil well end and "plug" the waterline by absorbing water and blocking the original high-permeability waterline channels and most of the artificial fractures. Furthermore, by introducing displacement fluid, an oil drainage channel is left to continue production and tap the remaining oil, thereby achieving the goal of reducing fluid volume and increasing oil production, while ensuring the long-term effectiveness of water plugging.

[0006] This invention performs "adjustment-plugging" fracturing on oil well fractures. The polymer gel has high final strength and strong shear resistance, adjusting and sealing the distal waterline. The bulk-expanding particles absorb water and expand rapidly, absorbing excess water and expanding in the middle to establish a second barrier. The resin sand has strong bonding properties, ensuring efficient sealing of the fracture opening. An oil drainage channel is reserved, utilizing fluid flow diversion to tap into potential benefits. Attached Figure Description

[0007] Figure 1 This is a schematic diagram of the fracturing method of the present invention.

[0008] Figure 2 This is a flowchart of the fracturing method of the present invention. Detailed Implementation

[0009] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0010] Unless otherwise specified, percentages (%) in this invention refer to mass percentages.

[0011] This invention provides a fracturing method for "adjustment-plugging" fractures in oil wells, the method comprising: introducing water-plugging material and displacement fluid into the target section of the target well, and simmering the well; the water-plugging material includes polymer gel, bulk-swelling particles and resin sand.

[0012] The "adjustment-plugging" fracturing method for oil well fractures of the present invention can both "adjust" the waterline by using polymer gel at the oil well end and "plug" the waterline by absorbing water and blocking the original high-permeability waterline channels and most of the artificial fractures. Furthermore, by introducing displacement fluid, an oil drainage channel is left to continue production and tap the remaining oil, thereby achieving the goal of reducing fluid volume and increasing oil production, while ensuring the long-term effectiveness of water plugging.

[0013] In this invention, a polymer gel adjusts and seals the distal waterline. Commonly used polymer gels can be used in this invention, and there are no special requirements for the composition of the polymer gel. For example, the polymer gel includes a polymer matrix A and a crosslinking agent I. The type and amount of polymer matrix A and crosslinking agent I can be selected according to existing technology. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, polymer matrix A is a suspension acrylamide terpolymer.

[0014] According to a preferred embodiment of the present invention, crosslinking agent I is selected from one or more of paraformaldehyde, resorcinol and ammonium chloride.

[0015] According to a preferred embodiment of the present invention, in the polymer gel, the content of polymer matrix A is 0.2%-0.3%, and the content of crosslinking agent I is 0.01%-0.3%.

[0016] In this invention, a wide range of properties can be selected for the polymer gel. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the final gel strength of the polymer gel is 5 × 10⁻⁶. 4 mPa·s⁻⁷×10⁻⁷ mPa·s⁻⁷ 4 mPa·s.

[0017] According to a preferred embodiment of the present invention, the breakthrough pressure gradient of the polymer gel is 1.2 MPa / cm to 1.6 MPa / cm. The aforementioned technical solution offers the advantages of both effective sealing and increased production efficiency.

[0018] In this invention, commonly used bulk-swellable particles can be used. There are no special requirements for the composition of the bulk-swellable particles. For example, the bulk-swellable particles include cross-linked acrylamide water-absorbing polymers, swelling agents, and fillers. The types and amounts of cross-linked acrylamide water-absorbing polymers, swelling agents, and fillers can be selected according to existing technologies. This invention will not elaborate on these points.

[0019] In this invention, the properties of the bulky particles can be selected from a wide range. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the particle size of the bulky particles is 1 mm to 2 mm.

[0020] According to a preferred embodiment of the present invention, the expansion ratio of the bulk-swelling particles is 6 to 10 times.

[0021] According to a preferred embodiment of the present invention, the pressure of the swollen particles is 13MPa-18MPa. The aforementioned technical solution has the advantages of both effective plugging and increased production and efficiency.

[0022] In this invention, commonly used resin sands can be used. There are no special requirements for the composition of the resin sand. For example, the resin sand includes quartz sand, resin and curing agent. The types and amounts of quartz sand, resin and curing agent can be selected according to the prior art. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the resin is phenolic resin and the curing agent is selected from ammonium chloride and / or ammonium sulfate.

[0023] In this invention, the properties of the resin sand can be selected from a wide range. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the particle size of the resin sand is 0.425mm-0.85mm.

[0024] According to a preferred embodiment of the present invention, the compressive strength of the resin sand is 16MPa-22MPa. The method employing the aforementioned technical solution has the advantages of both effective sealing and increased production efficiency.

[0025] In this invention, a displacement fluid is introduced to create an oil drain channel. The displacement fluid can be a gel fracturing fluid base. There are no special requirements for the composition of the gel fracturing fluid base. For example, the gel fracturing fluid base includes a polymer matrix B. The type and amount of polymer matrix B can be selected according to existing technology. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the polymer matrix B is a modified guar gum.

[0026] According to a preferred embodiment of the present invention, the content of polymer matrix B is 0.2%-0.5%.

[0027] In this invention, the objective can be achieved by introducing the aforementioned water-blocking material and displacement fluid into the target formation of the target well. The range of acceptable dosages for both the water-blocking material and displacement fluid is wide. Those skilled in the art can obtain the dosages of each using any method commonly used in the field. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the dosage of the polymer gel is calculated using the hemispherical volume method. The dosage of the polymer gel is as follows:

[0028]

[0029] In the formula, V1—the amount of polymer gel used, m 3 ;

[0030] r—the clogging radius of the polymer gel, 5m≤r≤8m;

[0031] — Formation porosity.

[0032] In this invention, the radius r in the formula for calculating the amount of polymer gel refers to the plugging radius of the polymer gel, where 5m ≤ r ≤ 8m. For example, the plugging radius r of the polymer gel is 5.5m, 6.0m, 6.5m, 7m, or 7.5m; formation porosity. The data was obtained through well logging. Considering potential losses, during the actual construction process, the actual dosage of polymer gel is generally adjusted to 110%-150% of V1 based on experience and actual conditions. The aforementioned technical solution offers the advantage of both effective plugging and increased production and efficiency.

[0033] According to a preferred embodiment of the present invention, the amount of the bulky particles is:

[0034] V2=(LL f -L y )WH / (1-C v )*2

[0035] In the formula, V2—amount of bulk-expanded particles, m3 ;

[0036] L—Total length of the artificial crack, in meters;

[0037] L f —Designed sealing length of resin sand, m, where the ratio of the designed sealing length of bulk-expanded particles to the designed sealing length of resin sand is (LL f -L y ) / L f =1:(1.5-5);

[0038] L y —Designed length of oil drain channel, in meters;

[0039] W—Width of the artificial crack, in meters;

[0040] H—Height of the artificial crack, in meters;

[0041] C v —Formation filtration coefficient;

[0042] In this invention, the design ratio of bulk-swellable particles to resin sand has a wide range of options and is generally adjusted according to the actual conditions of the target well. This invention exemplifies one implementation method but does not limit the scope of the invention. According to a preferred embodiment, the ratio of the designed plugging length of the bulk-swellable particles to the designed plugging length of the resin sand is (LL... f -L y ) / L f = 1:(1.5-5). The aforementioned technical solution has the advantage of both effectively blocking the blockage and increasing production and efficiency.

[0043] According to a preferred embodiment of the present invention, the amount of resin sand used is:

[0044] V3 = L f WH / (1-C v )*2

[0045] In the formula, V3—resin sand dosage, m 3 ;

[0046] L f - Resin sand design sealing length, m;

[0047] W - Width of the artificial crack, in meters;

[0048] H - Height of the artificial crack, in meters;

[0049] C v - Formation filtration coefficient.

[0050] According to a preferred embodiment of the present invention, the amount of the displacement fluid is:

[0051] V4 = L y WH+V g

[0052] In the formula, V4 represents the amount of displacement solution used, and m represents the volume of the displacement solution. 3 ;

[0053] L y -Designed length of oil drain channel, in meters;

[0054] W - Width of the artificial crack, in meters;

[0055] H - Height of the artificial crack, in meters;

[0056] V g -Tubing volume during fracturing operations, in meters 3 .

[0057] In this invention, those skilled in the art will understand that in the calculation formula for the dosage of bulk-swelling particles, resin sand, and displacement fluid, the total artificial fracture length L, artificial fracture width W, and artificial fracture height H are obtained by measuring the previous fracturing scale parameters of the target well and by software simulation methods; the designed reserved oil drainage channel length L... y Adjustments are made based on the total length of the artificial crack and the actual situation; this invention is not otherwise limited. The resin sand is designed to seal the crack to a length L. f Adjustments were made based on the total length of the artificial fractures and the design ratio of bulky particles to resin sand; formation filtration coefficient C. v The tubing volume V during fracturing operations was obtained through post-fracturing pressure drop testing. g Calculated using the volume calculation formula.

[0058] This invention performs "adjustment-plugging" fracturing on oil well fractures. The polymer gel has high final strength and strong shear resistance, adjusting and sealing the distal waterline. The bulk-expanding particles absorb water and expand rapidly, absorbing excess water and expanding in the middle to establish a second barrier. The resin sand has strong bonding properties, ensuring efficient sealing of the fracture opening and reserving an oil drainage channel to tap into potential benefits by utilizing fluid flow diversion.

[0059] In this invention, those skilled in the art will understand that polymer gel and displacement liquid can be directly introduced, while bulk-swellable particles and resin sand are generally introduced by a carrier liquid. Any method known to those skilled in the art can be used to introduce the aforementioned water-blocking materials such as polymer gel, bulk-swellable particles, and resin sand, as well as the displacement liquid. This invention exemplifies one implementation method but does not limit the scope of the invention. According to a preferred embodiment of the invention, the method for introducing the water-blocking material and displacement liquid includes: each at a depth of 0.5 m... 3 / min-2.5m 3A polymer gel, a carrier liquid A containing bulked particles, a carrier liquid B containing resin sand, and a displacement liquid are sequentially introduced at a discharge rate of / min. This technical solution offers the advantages of both effective plugging and increased production and efficiency.

[0060] In this invention, there are no special requirements for the type of carrier fluid. Commonly used carrier fluids can achieve the purpose of this invention. For example, the carrier fluid is a gel fracturing fluid.

[0061] In this invention, there are no special requirements for the composition of the gel fracturing fluid. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the gel fracturing fluid includes a polymer matrix B and a crosslinking agent II. The type and amount of polymer matrix B and crosslinking agent II can be selected according to the prior art. For example, polymer matrix B is modified guar gum, and crosslinking agent II is borax. In the gel fracturing fluid, the content of polymer matrix B is 0.2%-0.5%, and the content of crosslinking agent II is 1%-5%.

[0062] In this invention, those skilled in the art will understand that the function of the carrier liquid is to carry the bulked particles and resin sand separately into the container. During the process of the bulked particles and resin sand being carried into the container by the carrier liquid, there are no special requirements for the amount of carrier liquid used. It is generally adjusted according to the amount of bulked particles and resin sand used, as well as the discharge rate of the bulked particles and resin sand introduced (those skilled in the art will understand that the discharge rate of the bulked particles and resin sand introduced is the sand addition rate of the bulked particles and resin sand), the introduction time, etc. At the same time, any method known to those skilled in the art can be used to mix the bulked particles and resin sand separately with the carrier liquid, such as stirring the bulked particles and resin sand separately with the carrier liquid in a tanker.

[0063] In this invention, there are no special requirements for the fracturing equipment used to introduce the water-plugging material and displacement fluid. Commonly used fracturing equipment can be used in this invention, and the specific equipment can be selected according to the site conditions. For example, the water-plugging material and displacement fluid can be pumped in using a fracturing truck. The preparatory work before pumping includes well flushing, pressure testing, and test squeezing to ensure safe subsequent construction operations, as well as preparing the materials required for the operation, such as polymer gel, bulk-expanding particles, resin sand, and fracturing fluid, according to the design plan.

[0064] According to a preferred embodiment of the present invention, the method of introducing the water-blocking material and the displacement liquid includes: (1) using 0.8m 3 / min-1.2m 3 (2) The polymer gel is introduced at a flow rate of 1.2 m / min; 3 / min-1.8m 3 The carrier liquid A containing the bulky particles is introduced at a discharge rate of / min, wherein the discharge rate of the bulky particles, i.e., the sand addition rate of the bulky particles, is 0.2-0.8m. 3 / min; (3) at 1.8m 3 / min-2.2m 3 The resin-containing carrier liquid B is introduced at a discharge rate of / min, wherein the discharge rate of the resin sand, i.e., the sand addition rate, is 0.8-1.5m / min. 3 / min; (4) at 1.9m 3 / min-2.5m 3 The displacement fluid is introduced at a rate of / min. The aforementioned technical solution offers the advantages of both effective plugging and increased production and efficiency.

[0065] In this invention, during step (2) of introducing the carrier liquid A containing swollen particles, the discharge rate of the carrier liquid A containing swollen particles is generally kept constant, while the discharge rate of the swollen particles, i.e., the sand-adding speed of the swollen particles, is gradually increased in multiple stages. The range of possible differences in the discharge rates of adjacent swollen particle introductions, i.e., the sand-adding speed differences of the swollen particles, is relatively wide. This is an exemplary embodiment, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, during step (2) of introducing the carrier liquid A containing swollen particles, the discharge rate of the carrier liquid A containing swollen particles remains constant, and the discharge rate of the swollen particles, i.e., the sand-adding speed of the swollen particles, is gradually increased in 2-4 stages. The difference in the discharge rates of adjacent swollen particle introductions, i.e., the sand-adding speed differences of the swollen particles, is 0.1-0.3 m. 3 / min. The aforementioned technical solution has the advantage of both effectively blocking the blockage and increasing production and efficiency.

[0066] In this invention, during step (3) of introducing the carrier liquid B containing resin sand, the discharge rate of the carrier liquid B containing resin sand is generally increased gradually in multiple stages while keeping the discharge rate constant. The range of possible differences in the discharge rate between two adjacent introductions of resin sand (i.e., the difference in the resin sand addition rate) is relatively wide. This is an illustrative description of a preferred embodiment, but does not limit the scope of the invention. According to a preferred embodiment of the invention, during step (3) of introducing the carrier liquid B containing resin sand, the discharge rate of the carrier liquid B containing resin sand remains constant, and the discharge rate of the resin sand is increased gradually in 4-6 stages. The difference in the discharge rate between two adjacent introductions of resin sand (i.e., the difference in the resin sand addition rate) is 0.1-0.3 m. 3 / min. The aforementioned technical solution has the advantage of both effectively blocking the blockage and increasing production and efficiency.

[0067] In this invention, there are no special requirements for the simmering time of the well. It is generally adjusted according to the time of resin sand bonding, for example, the simmering time of the well is 2 to 10 days.

[0068] The method of the present invention is suitable for treating wells with high water cut caused by fractured water flooding. It typically selects a formation with relatively rich residual oil and potential for further development. There are no special requirements for parameters such as water cut, single-well production rate, porosity, oil saturation, and formation pressure level of the target well. The following is an illustrative description, but it does not limit the scope of the present invention. According to a preferred embodiment of the present invention, the water cut of the target well is 80%-100%, for example, water cut of 85%, 90%, 95%, and 98%.

[0069] According to a preferred embodiment of the present invention, the single-well recovery rate of the target well is 2%-40%, for example, 5%, 10%, 15%, 20%, 25%, 30% and 35%.

[0070] According to a preferred embodiment of the invention, the porosity of the target well is 10%-20%, for example, 12%, 14%, 16% and 18%.

[0071] According to a preferred embodiment of the present invention, the oil saturation of the target formation in the target well is 40%-100%, for example, 50%, 60%, 70%, 80%, 90% and 100%.

[0072] According to a preferred embodiment of the present invention, the formation pressure retention level of the target well is 80%-100%, for example, 85%, 90% and 95%.

[0073] A schematic diagram of the fracturing method of the present invention is shown below. Figure 1 ,like Figure 1 As shown: The fracturing method of the present invention sequentially introduces polymer gel at the oil well end: polymer gel is introduced at slug 1, bulk-swellable particles are introduced at slug 2, resin sand is introduced at slug 3, and an oil drainage channel is reserved.

[0074] The flowchart of the fracturing method of the present invention is shown below. Figure 2 ,like Figure 2 As shown, the fracturing method of the present invention includes the following steps: first, selecting the target well and the target formation; then, selecting the type of water-blocking material, clarifying the order of addition and the dosage; then, performing "adjustment-plugging" fracturing operation, pumping the water-blocking material into the target well at a low discharge rate to replace it; and finally, opening the well and releasing the flow for production after shutting down the well.

[0075] The "adjustment-plugging" fracturing method for oil well fractures of the present invention can both "adjust" the waterline by using polymer gel at the oil well end and "plug" the waterline by absorbing water and blocking the original high-permeability waterline channels and most of the artificial fractures. Furthermore, by introducing displacement fluid, an oil drainage channel is left to continue production and tap the remaining oil, thereby achieving the goal of reducing fluid volume and increasing oil production, while ensuring the long-term effectiveness of water plugging.

[0076] This invention performs "adjustment-plugging" fracturing on oil well fractures. The polymer gel has high final strength and strong shear resistance, adjusting and sealing the distal waterline. The bulk-expanding particles absorb water and expand rapidly, absorbing excess water and expanding in the middle to establish a second barrier. The resin sand has strong bonding properties, ensuring efficient sealing of the fracture opening. An oil drainage channel is reserved, utilizing fluid flow diversion to tap into potential benefits.

[0077] The present invention will be described in detail below through examples.

[0078] In the following examples and comparative examples:

[0079] The test method for the final gel strength and breakthrough pressure of polymer gels, and the breakthrough pressure of bulk swell particles, is the sand-filled tube test.

[0080] The test method for the particle size of bulk-expanded particles and resin sand is to measure it using vernier calipers.

[0081] The method for testing the expansion ratio of bulky granules is as follows: measure the volume change of the bulky granules before and after soaking in water for 30 minutes.

[0082] The method for testing the compressive strength of resin sand is as follows: after the resin sand is cured at 60-80 degrees Celsius for 48 hours, the compressive strength is tested through a sand-filled tube test.

[0083] The water cut of the target well was measured using production data analysis.

[0084] The method for calculating the single-well recovery rate of the target well is: Recovery rate = Production volume / Geological reserves * 100%.

[0085] The porosity of the target well was measured using density logging.

[0086] The method for testing the oil saturation of the target interval in the target well is: to measure it using density logging.

[0087] The formation pressure holding level of the target well in the target section is tested by measuring the pressure using the liquid level method.

[0088] In the formula:

[0089] The clogging radius of polymer gel is 5m ≤ r ≤ 8m.

[0090] Formation porosity It was obtained through well logging methods.

[0091] The total length L, width W, and height H of the artificial fractures were measured using parameters from the previous fracturing operation of the target well and software simulation methods.

[0092] The design includes a reserved oil drain channel with a length L. yAdjustments are made based on the total length of the artificial crack and the actual situation, as those skilled in the art will know, and this invention is not otherwise limited.

[0093] Formation filtration coefficient C v The test method is obtained through analysis of the post-pressure drop test method.

[0094] Tubing volume V during fracturing operation g Calculated using the volume calculation formula.

[0095] The materials used in the examples and comparative examples are all commercially available.

[0096] In the following examples and comparative examples, the selected target oil wells and target formations, water cut, single-well production level, oil saturation, formation pressure retention level, formation porosity, formation filtration coefficient, and parameters such as the total length, width, and height of the artificial fractures from the previous fracturing operation are shown in Table 1. As can be seen from Table 1, the parameters of the oil wells selected in this invention are slightly different, but all are suitable for fracturing using the method of this invention.

[0097] Example 1

[0098] For a high water-cut oil well undergoing fracture "adjustment-plugging" fracturing, the following conditions were met before fracturing of the target well and the surrounding formation: As shown in Table 1, the water cut of the target well was 100%, the single-well production rate of the target well was 6%, and the porosity of the target well was 15%; the oil saturation of the target formation was 82.5%, the formation pressure retention level of the target formation was 83.2%, the formation filtration coefficient was 0.3, the total length of the artificial fractures in the previous fracturing was 77m, the width of the artificial fractures in the previous fracturing was 0.01m, and the height of the artificial fractures in the previous fracturing was 38m.

[0099] The dosages of polymer gel, bulk-swellable particles, resin sand, and displacement fluid are calculated according to the formula, as shown in Table 2. The plugging radius r of the polymer gel is 8m; the designed plugging length L of the resin sand is... f The length is 44m; the designed reserved oil drain channel length L y The tubing volume V during fracturing operations is 22m. g It is 4.6m 3 Calculations show that the amount of polymer gel used (considering losses, the amount of polymer gel used is the calculated value multiplied by 130%) is 209m³. 3 The dosage of the bulked granules is 12m³. 3 The amount of resin sand used is 48m³. 3 The amount of displacement fluid used was 13m. 3 .

[0100] The construction steps are as follows:

[0101] Step 1: Preparatory work before construction, including well cleaning, pressure testing, and extrusion testing to ensure safe construction. Prepare materials required for the operation, such as polymer gel, bulking particles, resin sand, and fracturing fluid.

[0102] The polymer gel comprises 0.25% suspension acrylamide terpolymer, 0.15% paraformaldehyde, 0.05% resorcinol, and 0.05% ammonium chloride; the final gel strength of the polymer gel is 6×10⁻⁶. 4 mPa·s; The breakthrough pressure of the polymer gel is 1.4 MPa / cm;

[0103] The expanded granules include cross-linked acrylamide-based water-absorbing polymers, expanding agents, and fillers; the particle size of the expanded granules is 1-2 mm; the expansion ratio of the expanded granules is 8 times; and the breakthrough pressure of the expanded granules is 15 MPa.

[0104] Resin sand includes quartz sand, phenolic resin, ammonium chloride, and ammonium sulfate; the particle size of resin sand is 0.425-0.85 mm; the compressive strength of resin sand after curing at 60 degrees Celsius for 48 hours is 18 MPa, and the compressive strength after curing at 80 degrees Celsius for 48 hours is 21 MPa.

[0105] The displacement fluid is a gel fracturing fluid base fluid, and the composition of the gel fracturing fluid is: 0.4% modified guar gum and 3.5% borax crosslinking agent.

[0106] Step 2: Introduce water-plugging material and displacement fluid using the fracturing truck unit:

[0107] With 1m 3 / min displacement introduced 209m 3 Polymer gel;

[0108] At 1.5m 3 A flow rate of / min introduces 12m of fracturing fluid carried by 0.4% gel fracturing fluid. 3 The fracturing fluid containing 0.4% gel containing the swellable particles was introduced at a constant rate. The rate at which the swellable particles were introduced (i.e., the sand-addition rate) was gradually increased in three stages, with each stage starting at 0.3 m³ / s. 3 / min, 0.5m 3 / min and 0.7m 3 / min;

[0109] With 2m 3 / min displacement introduces 48m of fracturing fluid carried by 0.4% gel fracturing fluid. 3Resin-coated fracturing fluid containing 0.4% resin sand was introduced at a constant rate. The rate of resin sand introduction (i.e., the rate at which the resin sand was added) was gradually increased in five stages, with each stage starting at 0.8 m³ / s. 3 / min, 0.9m 3 / min, 1.0m 3 / min, 1.1m 3 / min and 1.3m 3 / min;

[0110] With 2m 3 / min displacement introduced 13m 3 The 0.45% gel fracturing fluid base was used as a substitute;

[0111] Step 3: Seal the well for 6 days;

[0112] Step 4: Open the well and reverse discharge production.

[0113] Following the above method, the water cut of this well decreased by 14.4 percentage points and the daily oil production increased by 0.9t, achieving the goal of reducing fluid content and increasing oil production. The daily oil production and water cut values ​​before and after fracturing are shown in Table 3.

[0114] Example 2

[0115] According to the method in Example 1, another high water-cut oil well was subjected to fracture "adjustment-plugging" fracturing. Before the fracturing operation of the target well and the target section, the following parameters were selected: water cut, single well production degree, porosity, oil saturation, formation pressure retention level, formation filtration coefficient, and the total length, width, and height of the artificial fractures from the previous fracturing operation. These parameters are shown in Table 1.

[0116] The amounts of polymer gel, bulked particles, resin sand, and displacement fluid were calculated according to the formula, wherein: Unlike Example 1, the plugging radius r of the polymer gel is 6m, and the designed plugging length L of the resin sand is... f Design reserved oil drain channel length L y The tubing volume V during fracturing operations g And after calculation: the amount of polymer gel (considering losses, the amount of polymer gel is the calculated value multiplied by 130%), the amount of bulk granules, the amount of resin sand and the amount of displacement liquid are shown in Table 2.

[0117] In the construction steps: the difference from Example 1 is that the amount of polymer gel, the amount of bulk granules, the amount of resin sand and the amount of displacement liquid are shown in Table 2; the other conditions and materials are the same.

[0118] Based on the above method, the daily oil production and water cut values ​​of this well before and after fracturing are shown in Table 3.

[0119] Example 3

[0120] Following the method in Example 1, another high water-cut oil well was subjected to fracture "adjustment-plugging" fracturing. The selected target well and target interval water cut, single well production degree, porosity, oil saturation, formation pressure retention level, formation filtration coefficient, and parameters such as the total length, width, and height of the artificial fractures from the previous fracturing are shown in Table 1.

[0121] The amounts of polymer gel, bulk-swellable particles, resin sand, and displacement solution were calculated according to the formula. The difference from Example 1 is that the ratio of the designed plugging length of the bulk-swellable particles to the designed plugging length of the resin sand is 1:1. The plugging radius r of the polymer gel and the designed plugging length L of the resin sand are... f The design includes the length of the reserved oil drain channel and the tubing volume V during fracturing operations. g And after calculation: the amount of polymer gel (considering losses, the amount of polymer gel is the calculated value multiplied by 130%), the amount of bulk granules, the amount of resin sand and the amount of displacement liquid are shown in Table 2.

[0122] In the construction steps: the difference from Example 1 is that the amount of polymer gel, the amount of bulk granules, the amount of resin sand and the amount of displacement liquid are shown in Table 2; the other conditions and materials are the same.

[0123] Based on the above method, the daily oil production and water cut values ​​of this well before and after fracturing are shown in Table 3.

[0124] Example 4

[0125] The method of Example 1 was used to perform fracture "adjustment-plugging" fracturing on another high water-cut oil well. The selected target well and target interval water cut, single well production degree, porosity, oil saturation, formation pressure level, formation filtration coefficient, and parameters such as the total length, width, and height of the artificial fractures in the previous fracturing are shown in Table 1.

[0126] The dosages of polymer gel, bulked particles, resin sand, and displacement fluid are calculated according to the formula, where: the plugging radius r of the polymer gel and the designed plugging length L of the resin sand are... f Design reserved oil drain channel length L y The tubing volume V during fracturing operations g And after calculation: the amount of polymer gel (considering losses, the amount of polymer gel is the calculated value multiplied by 130%), the amount of bulk granules, the amount of resin sand and the amount of displacement liquid are shown in Table 2.

[0127] In the construction process: Unlike Example 1, the final gel strength of the polymer gel used is 4 × 10⁻⁶. 4mPa·s; the breakthrough pressure gradient of the polymer gel is 1.0 MPa / cm; the dosage of polymer gel, bulk granules, resin sand and displacement liquid are shown in Table 2; all other conditions and materials are the same.

[0128] Based on the above method, the daily oil production and water cut values ​​of this well before and after fracturing are shown in Table 3.

[0129] Example 5

[0130] The method of Example 1 was used to perform fracture "adjustment-plugging" fracturing on another high water-cut oil well. The selected target well and target interval water cut, single well production degree, porosity, oil saturation, formation pressure level, formation filtration coefficient, and parameters such as the total length, width, and height of the artificial fractures in the previous fracturing are shown in Table 1.

[0131] The dosages of polymer gel, bulked particles, resin sand, and displacement fluid are calculated according to the formula, where: the plugging radius r of the polymer gel and the designed plugging length L of the resin sand are... f Design reserved oil drain channel length L y The tubing volume V during fracturing operations g And after calculation: the amount of polymer gel (considering losses, the amount of polymer gel is the calculated value multiplied by 130%), the amount of bulk granules, the amount of resin sand and the amount of displacement liquid are shown in Table 2.

[0132] In the construction steps: Unlike Example 1, the particle size of the expanded particles used is 0.5-1.0 mm, the expansion ratio of the expanded particles is 4 times, and the breakthrough pressure of the expanded particles is 10 MPa; the amount of polymer gel, expanded particles, resin sand and displacement liquid are shown in Table 2; the other conditions and materials are the same.

[0133] Based on the above method, the daily oil production and water cut values ​​of this well before and after fracturing are shown in Table 3.

[0134] Example 6

[0135] The method of Example 1 was used to perform fracture "adjustment-plugging" fracturing on another high water-cut oil well. The selected target well and target interval water cut, single well production degree, porosity, oil saturation, formation pressure level, formation filtration coefficient, and parameters such as the total length, width, and height of the artificial fractures in the previous fracturing are shown in Table 1.

[0136] The dosages of polymer gel, bulked particles, resin sand, and displacement fluid are calculated according to the formula, where: the plugging radius r of the polymer gel and the designed plugging length L of the resin sand are... f Design reserved oil drain channel length L y The tubing volume V during fracturing operations gAnd after calculation: the amount of polymer gel (considering losses, the amount of polymer gel is the calculated value multiplied by 130%), the amount of bulk granules, the amount of resin sand and the amount of displacement liquid are shown in Table 2.

[0137] In the construction steps: Unlike Example 1, the resin sand used has a particle size of 1-2 mm. The compressive strength of the resin sand after curing at 60 degrees Celsius for 48 hours is 12 MPa, and the compressive strength after curing at 80 degrees Celsius for 48 hours is 15 MPa. The amounts of polymer gel, bulk granules, resin sand, and displacement liquid are shown in Table 2. All other conditions and materials are the same.

[0138] Based on the above method, the daily oil production and water cut values ​​of this well before and after fracturing are shown in Table 3.

[0139] Example 7

[0140] The method of Example 1 was used to perform fracture "adjustment-plugging" fracturing on another high water-cut oil well. The selected target oil well and target interval water cut, single well production degree, porosity, oil saturation, formation pressure holding level, formation filtration coefficient, and the total length, width, and height of the artificial fractures from the previous fracturing are shown in Table 1.

[0141] The dosages of polymer gel, bulked particles, resin sand, and displacement fluid are calculated according to the formula, where: radius r, designed sealing length of resin sand L... f Design reserved oil drain channel length L y The tubing volume V during fracturing operations g And after calculation: the amount of polymer gel (considering losses, the amount of polymer gel is the calculated value multiplied by 130%), the amount of bulk granules, the amount of resin sand and the amount of displacement liquid are shown in Table 2.

[0142] In the construction process, unlike Example 1, the displacement of the 0.4% gel fracturing fluid containing the swellable particles and resin sand was 1.9 m³. 3 The rate at which the bulky particles are introduced (i.e., the sand-adding speed of the bulky particles) is gradually increased in three stages, with the initial rate being 0.3 m / min. 3 / min, 0.5m 3 / min, 0.7m 3 / min;

[0143] The displacement of the 0.4% resin-containing gel fracturing fluid introduced was 2.3 m³. 3 The rate at which resin sand is introduced (i.e., the rate at which resin sand is added) is gradually increased in three stages, with the rate increasing sequentially by 0.9 m / min. 3 / min, 1.1m 3 / min, 1.3m 3 / min.

[0144] The dosages of polymer gel, bulked particles, resin sand, and displacement solution are shown in Table 2.

[0145] All other conditions and materials are the same;

[0146] Based on the above method, the daily oil production and water cut values ​​of this well before and after fracturing are shown in Table 3.

[0147] Comparative Example 1

[0148] Following the method in Example 1, another high water-cut oil well was subjected to fracture "adjustment-plugging" fracturing. The selected target well and target interval water cut, single well production degree, porosity, oil saturation, formation pressure retention level, formation filtration coefficient, and parameters such as the total length, width, and height of the artificial fractures from the previous fracturing are shown in Table 1.

[0149] Unlike Example 1, no polymer gel was added, and the clogging radius r of the polymer gel was 0m.

[0150] The dosages of bulk-swelling particles, resin sand, and displacement fluid are calculated according to the formula, where: the adjustment radius r of the polymer gel, the design sealing length L of the resin sand, and the displacement fluid are all specified. f The design includes the length of the reserved oil drain channel and the tubing volume V during fracturing operations. g And after calculation: the dosage of bulk-swellable particles, the dosage of resin sand and the dosage of displacement liquid are shown in Table 2;

[0151] In the construction steps: Unlike Example 1, no polymer gel was added. The amounts of bulk-swellable particles, resin sand, and displacement liquid are shown in Table 2; all other conditions and materials are the same.

[0152] Based on the above method, the daily oil production and water cut values ​​of this well before and after fracturing are shown in Table 3.

[0153] Comparative Example 2

[0154] Following the method in Example 1, another high water-cut oil well was subjected to fracture "adjustment-plugging" fracturing. The selected target well and target interval water cut, single well production degree, porosity, oil saturation, formation pressure retention level, formation filtration coefficient, and parameters such as the total length, width, and height of the artificial fractures from the previous fracturing are shown in Table 1.

[0155] Unlike Example 1, no bulk-swelling particles were added, thus increasing the resin sand design sealing length L. f .

[0156] The dosages of polymer gel, resin sand, and displacement fluid are calculated according to the formula, where: the plugging radius r of the polymer gel and the designed plugging length L of the resin sand are... f The design includes the length of the reserved oil drain channel and the tubing volume V during fracturing operations. g And after calculation: the amount of polymer gel, the amount of resin sand and the amount of displacement liquid are shown in Table 2;

[0157] In the construction steps: Unlike Example 1, the amounts of polymer gel, resin sand and displacement liquid are shown in Table 2, while the other conditions and materials are the same.

[0158] Based on the above method, the daily oil production and water cut values ​​of this well before and after fracturing are shown in Table 3.

[0159] Comparative Example 3

[0160] Following the method in Example 1, another high water-cut oil well was subjected to fracture "adjustment-plugging" fracturing. The selected target oil well and target interval water cut, single well production degree, porosity, oil saturation, formation pressure holding level, formation filtration coefficient, and parameters such as the total length, width, and height of the artificial fractures from the previous fracturing are shown in Table 1.

[0161] Unlike Example 1, no polymer gel or bulked particles were added, and the resin sand design sealing length L was increased. f .

[0162] The dosage of resin sand and displacement fluid is calculated according to the formula, where: the plugging radius r of the polymer gel and the designed plugging length L of the resin sand are... f The design includes the length of the reserved oil drain channel and the tubing volume V during fracturing operations. g And after calculation, the dosage of resin sand and displacement liquid is shown in Table 2;

[0163] In the construction steps: the difference from Example 1 is that the amount of resin sand and displacement liquid used is shown in Table 2; the other conditions and materials are the same.

[0164] Based on the above method, the daily oil production and water cut values ​​of this well before and after fracturing are shown in Table 3.

[0165] Table 1

[0166]

[0167] Table 2

[0168]

[0169] Table 3

[0170]

[0171] The results above show that the "adjustment-plugging" fracturing method for oil well fractures of the present invention can effectively plug the fractures and increase production and efficiency, resulting in significantly better performance.

[0172] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A fracturing method for "adjustment-plugging" fractures in oil wells, characterized in that, The method includes: introducing water-blocking material and displacement fluid into the target section of the target well, and saturating the well; the water-blocking material includes polymer gel, bulk-swelling particles and resin sand.

2. The method according to claim 1, characterized in that, The polymer gel comprises a polymer matrix A and a crosslinking agent I; Among them, polymer matrix A is a suspension acrylamide terpolymer; Crosslinking agent I is selected from one or more of paraformaldehyde, resorcinol, and ammonium chloride; In the polymer gel, the content of polymer matrix A is 0.2%-0.3% by weight, and the content of crosslinking agent I is 0.01%-0.3%.

3. The method according to claim 1 or 2, characterized in that, The final gel strength of the polymer gel is 5×10. 4 mPa·s⁻⁷×10⁻⁷ mPa·s⁻⁷ 4 mPa·s; The breakthrough pressure gradient of the polymer gel is 1.2 MPa / cm to 1.6 MPa / cm.

4. The method according to claim 1 or 2, characterized in that, The bulked particles comprise cross-linked acrylamide-based water-absorbing polymers, a swelling agent, and a filler.

5. The method according to claim 1 or 2, characterized in that, The particle size of the bulky particles is 1mm-2mm; The expansion ratio of the bulk-swelling particles is 6 to 10 times; The breakthrough pressure of the swollen particles is 13MPa-18MPa.

6. The method according to claim 1 or 2, characterized in that, The resin sand includes quartz sand, resin, and curing agent.

7. The method according to claim 1 or 2, characterized in that, The resin sand has a particle size of 0.425mm-0.85mm; The compressive strength of the resin sand is 16MPa-22MPa.

8. The method according to claim 1 or 2, characterized in that, The displacement fluid is a gel fracturing fluid base fluid.

9. The method according to claim 1 or 2, characterized in that, The amount of the polymer gel used is: In the formula, V1—the amount of polymer gel used, m 3 ; r—the clogging radius of the polymer gel, 5m≤r≤8m; — Formation porosity.

10. The method according to claim 1 or 2, characterized in that, The amount of the bulky granules used is: V2=(L-L f -L y )WH / (1-C v )*2 In the formula, V2—amount of bulk-expanded particles, m 3 ; L—Total length of the artificial crack, in meters; L f —Designed sealing length of resin sand, m, where the ratio of the designed sealing length of bulk-expanded particles to the designed sealing length of resin sand is (LL f -L y ) / L f =1:(1.5-5); L y —Designed length of oil drain channel, in meters; W—Width of the artificial crack, in meters; H—Height of the artificial crack, in meters; C v — Formation filtration coefficient.

11. The method according to claim 1 or 2, characterized in that, The amount of resin sand used is: V3 = L f WH / (1-C v )*2 In the formula, V3—resin sand dosage, m 3 ; L f —Designed sealing length of resin sand, in meters; W—Width of the artificial crack, in meters; H—Height of the artificial crack, in meters; C v — Formation filtration coefficient.

12. The method according to claim 1 or 2, characterized in that, The amount of the displacement solution used is: V4=L y WH+V g In the formula, V4—volume of displacement solution, m 3 ; L y —Designed length of oil drain channel, in meters; W—Width of the artificial crack, in meters; H—Height of the artificial crack, in meters; V g —Tubing volume during fracturing operations, in meters 3 .

13. The method according to claim 1 or 2, characterized in that, Methods for introducing water-blocking materials and displacement fluid include: each at a depth of 0.5m... 3 / min-2.5m 3 A flow rate of / min is used to sequentially introduce polymer gel, carrier liquid A containing bulked particles, carrier liquid B containing resin sand, and displacement liquid.

14. The method according to claim 13, characterized in that, Methods for introducing plugging materials and displacement fluids include: (1) With 0.8m 3 / min-1.2m 3 The polymer gel is introduced at a rate of / min; (2) With 1.2m 3 / min-1.8m 3 The carrier liquid A containing the bulky particles is introduced at a rate of 0.2-0.8 m³ / min, wherein the rate of introduction of the bulky particles is 0.2-0.8 m³ / min. 3 / min; (3) With 1.8m 3 / min-2.2m 3 The resin-containing carrier liquid B is introduced at a discharge rate of 0.8-1.5 m³ / min, wherein the discharge rate of the resin sand is 0.8-1.5 m³ / min. 3 / min; (4) at 1.9m 3 / min-2.5m 3 The displacement fluid is introduced at a rate of / min.

15. The method according to claim 1 or 2, wherein, The well-sealing time is 2 to 10 days; The water cut of the target well is 80%-100%; The single-well recovery rate of the target well is 2%-40%; The porosity of the target well is 10%-20%; The oil saturation of the target formation in the target well is 40%-100%; The formation pressure retention level of the target well in the target section is 80%-100%.

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