Horizontal well chemical plugging shaft reconstruction method

Abstract

The invention belongs to the field of oil production engineering, and particularly relates to a horizontal well chemical plugging shaft reconstruction method which comprises the following steps: pulling out a horizontal well production pipe column from a stratum, pigging to an artificial well bottom, and injecting clear water to carry out reverse circulation well washing; the imbibition liquid is injected into the stratum through the energy supplementing pipe column till the stratum pressure is kept horizontal and recovered to 95% or above; a first-stage drillable insertion pipe packer with a first-stage oil pipe is put down into the stratum; injecting gel into the primary fracturing crack to fill the support crack; and after the sealing resin plugging agent is injected for replacement, the first-stage oil pipe is pulled out for backwashing and then is lifted up until plugging of each section of primary fracturing crack is completed. According to the method, after the drillable insertion pipe packer is applied and matched with the easy-to-drill-and-grind resin material, the old seam of the horizontal well is precisely blocked in a segmented mode, and the horizontal well shaft is drilled and ground, the problems that in horizontal well refracturing, the construction efficiency is low, a pipe moves outwards, and the size of a sleeve is reduced when a small shaft is reconstructed are solved; and follow-up bridge shooting continuous operation volume fracturing construction and horizontal well efficient repeated fracturing operation can be achieved.

Description

Technical Field

[0001] The invention belongs to the field of oil production engineering, and particularly relates to a horizontal well chemical plugging wellbore reconstruction method. Background Art

[0002] The matrix permeability of ultra-low permeability reservoirs is low (<1.0×10 -3 μm 2 ), staged fracturing of horizontal wells has been applied on a large scale in ultra-low permeability blocks, and the production of single wells has been improved. However, with the extension of horizontal well development time, some horizontal wells have low production, which is mainly affected by factors such as the low initial transformation degree and the reduced conductivity of the fracture system. Repeated fracturing is needed to restore the production of single wells and improve the development effect.

[0003] At present, the following problems exist in repeated fracturing of horizontal wells: First, the double-seal single-card process used in repeated fracturing of horizontal wells has a small number of transformation sections in a single drilling trip, and many trips and drillings, resulting in low operating efficiency; second, the wellbore of old horizontal wells is incomplete, and the problem of pipe leakage between fracture sections is prominent, which seriously affects the effectiveness of pressure distribution; third, the construction of technologies such as small-casing wellbore reconstruction and casing-subsidized wellbore reconstruction causes casing diameter reduction, affecting subsequent oil production and well repair operations.

[0004] The patent with the publication number CN116220608A proposes a horizontal well segmented plugging method, which divides the horizontal well formation into multiple partitions based on the absorption information of the horizontal well formation; determines the composition of the plugging agent of each partition according to the absorption information of each partition; and injects the corresponding plugging agent into each partition. This makes the plugging of well sections with different permeabilities in the horizontal well more targeted, but the method does not propose a specific plugging method, and the use of multiple plugging agents is also relatively complicated in practical application. Summary of the invention

[0005] In view of the above problems, the present invention proposes a horizontal well chemical plugging wellbore reconstruction method, comprising the following steps:

[0006] S1: The horizontal well production string is pulled out from the formation and passed to the bottom of the artificial well, and clean water is injected for reverse circulation to wash the well;

[0007] S2: Inject imbibition fluid into the formation using the energy replenishment string until the formation pressure is restored to a level above 95%;

[0008] S3: inserting a first-stage drillable intubation packer with a first-stage oil pipe into the formation;

[0009] S4: injecting gel into the primary fracturing cracks using the first-stage oil pipe to fill the propped cracks;

[0010] S5: After the gel is injected, a sealing resin plugging agent is injected through the first-stage oil pipe for displacement. After displacement, the first-stage oil pipe is pulled out and backwashed and then lifted up; steps S3-S5 are repeated until each section of the primary fracturing crack is plugged.

[0011] Furthermore, in step S1, the water quality of the water inlet and the water outlet are consistent after the reverse circulation well washing to the backwashing oil pipe.

[0012] Furthermore, in step S3, the first-stage drillable intubation packer is lowered to a position 2 m above the plugged perforation section.

[0013] Furthermore, the method performs the following operations after completing the plugging of each primary fracturing crack:

[0014] The plugged fractures are allowed to solidify for 2-4 days, and the horizontal wellbore is drilled and ground;

[0015] The treated horizontal wellbore is pressure tested, and bridge-shot fracturing construction is carried out after the pressure test is successful.

[0016] Furthermore, in step S2, the injection volume of the imbibition fluid is 95% of the produced fluid volume of the well;

[0017] The imbibition liquid is ES-2 imbibition agent with a mass fraction of 0.3%.

[0018] Furthermore, the energy-boosting string in step S2 is provided with multiple sections from the bottom of the well to the wellhead, including in sequence: a bottom energy-boosting string and a middle energy-boosting string;

[0019] Wherein, the bottommost energy supplement string includes a one-way valve close to the bottom of the well and a sandblaster connected to the one-way valve, and the sandblaster is connected to an end away from the bottom of the well;

[0020] The intermediate section energy supplement pipe string is provided with multiple sections, and each intermediate section energy supplement pipe string includes a sliding sleeve seat, a packer and a sandblaster in sequence from the bottom of the well to the wellhead;

[0021] Each energy-boosting string below the deflection point is installed using chamfered coupling tool tubing, and each energy-boosting string above the deflection point is installed using ordinary tool tubing.

[0022] Furthermore, the packer is a K344 packer, the chamfered coupling tool tubing is a Φ73 mm chamfered coupling tool tubing, and the common tool tubing is a Φ73 mm tool tubing.

[0023] Furthermore, the gel in step S4 is FL-1 gel, and the amount of gel used is the amount of proppant used for initial fracturing.

[0024] Furthermore, the resin plugging agent formula in step S5 is composed of a main agent and a curing agent;

[0025] The main agent is phenolic resin and urea-formaldehyde resin in a volume ratio of 1:1.3, and the curing agent is 0.15% methyl ethyl ketone peroxide.

[0026] Furthermore, in step S5, the displacement amount of the sealing resin plugging agent injected is the inner volume of the first-stage tubing above the first-stage drillable intubating packer.

[0027] Beneficial effects of the present invention:

[0028] The present invention aims to solve the problem that the chemical plugging of old fractures in horizontal wells is not precise enough. By using a drillable intubation packer and matching easy-to-drill and grind resin materials, the old fractures in horizontal wells can be accurately plugged in sections. After drilling and grinding the wellbore of the horizontal well, the original 5 1 / 2 The casing integrity can realize subsequent bridge-shot volume fracturing construction and realize efficient repeated fracturing operation of horizontal wells. The present invention solves the problems of low construction efficiency, pipe leakage and small casing size reduction in repeated fracturing of horizontal wells.

[0029] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing 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, claims and 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 A flow chart of a horizontal well chemical plugging wellbore reconstruction method proposed by the present invention is shown;

[0032] Figure 2 A schematic diagram of an energy replenishment column in an embodiment of the present invention is shown;

[0033] Figure 3 The production curve diagram of the horizontal well before and after chemical plugging in the embodiment of the present invention is shown. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are 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.

[0035] The staged fracturing technology of horizontal wells refers to the friction resistance of the perforated holes that will be generated when the fracturing fluid enters the reservoir at a high speed, and it will increase with the increase of pumping volume, driving the bottom hole pressure to rise. Once the bottom hole pressure exceeds the fracture pressure of multiple fractured layers, cracks will be opened in each layer. It requires that the fracture pressure of each layer is basically close, which can be adjusted by the friction resistance of the perforated holes. Staged fracturing technology is one of the key supporting technologies for horizontal wells. The use of staged fracturing can complete the fracturing of multiple reservoirs at one time in a relatively short time, and minimize the damage to the reservoir, so as to achieve multi-layer joint production, thereby achieving the purpose of increasing the production of a single well and maximizing the degree of geological reserves available.

[0036] The present invention proposes a horizontal well chemical plugging wellbore reconstruction method, such as Figure 1 As shown, the specific steps include:

[0037] S1: Pull out the horizontal well production string from the formation and run it to the bottom of the artificial well, inject clean water for reverse circulation to wash the well; wash the well until the water quality at the water inlet and outlet is consistent;

[0038] S2: Inject imbibition fluid into the formation using the energy replenishment string until the formation pressure is restored to a level above 95%;

[0039] This step is to use the energy supplement string to supplement the formation energy construction, and remove the energy supplement string after completing the energy supplement; wherein, the injection volume of the injected imbibition fluid is 95% of the produced fluid volume of this well, and the formula of the imbibition fluid is ES-2 imbibition agent with a mass fraction of 0.3%;

[0040] The energy replenishment process is a fixed pipe injection process, which specifically injects the imbibed fluid into the formation in large sections, reducing the operation procedures of raising and lowering the energy replenishment pipe, reducing the operation cost, and shortening the well occupation period of the energy replenishment operation procedure.

[0041] The energy replenishment string in step S2 is arranged in multiple sections from the bottom of the well to the wellhead, which includes:

[0042] The bottom energy replenishment string and the middle section energy replenishment string; wherein the middle section energy replenishment string is provided with multiple sections;

[0043] The bottommost energy supplement pipe string includes a one-way valve close to the bottom of the well and a sandblaster connected to the one-way valve, wherein the sandblaster is connected to an end away from the bottom of the well;

[0044] Each intermediate section of the energy supplement string includes a sliding sleeve seat, a packer and a sandblaster in sequence from the bottom of the well to the wellhead;

[0045] Each energy-boosting string below the deflection point is installed using chamfered coupling tool tubing, and each energy-boosting string above the deflection point is installed using ordinary tool tubing.

[0046] In an exemplary embodiment of the present invention, the structure of the energy supplement string is as follows: Figure 2 As shown, the energy replenishment string includes from the bottom of the well to the wellhead in sequence: a check valve, a sleeve seat, a packer, a sleeve sandblaster (i.e., the sandblaster in the figure), a chamfered tool tubing, a sleeve seat, a packer, a sleeve sandblaster, a chamfered tool tubing, a packer, a chamfered coupling tool tubing (20m above the inclination point) and a tool tubing to the wellhead, and the above structures are all adapted. In one embodiment of the present invention, the packer is a K344 packer, the chamfered tool tubing is a Φ73mm chamfered tool tubing, the chamfered coupling tool tubing is a Φ73mm chamfered coupling tool tubing, and the tool tubing is a Φ73mm tool tubing.

[0047] A packer refers to a downhole tool connected to the downhole tubing and used to seal the annular space between the oil pipe and the oil and gas well casing or the open hole wall. The K344 expandable packer is composed of an expansion sealing rubber tube, a central pipe, a coupling and other components. It can be used in oil field stratified water injection, stratified acidification, stratified plugging, stratified fracturing and other construction processes. When the K344 packer is lowered to the predetermined position, hydraulic pressure is added from the oil pipe. When the internal and external pressure difference reaches 0.5-0.7Mpa, the rubber tube expands, seals the annular space of the oil casing, releases the pressure in the oil pipe, and the rubber tube is retracted and unsealed.

[0048] S3: lowering a first-stage drillable intubation packer with a first-stage oil pipe into the formation; the first-stage drillable intubation packer is lowered to a position 2 m above the perforation section to be plugged;

[0049] S4: using the first-stage oil pipe to inject gel into the primary fracturing crack to fill the propped crack; specifically, FL-1 gel can be used; the amount of injected gel is the amount of proppant used in the initial fracturing;

[0050] S5: After the gel is injected, the sealing resin plugging agent is injected through the first-stage oil pipe to replace it, and then the first-stage oil pipe is pulled out, and the first-stage oil pipe is backwashed and then lifted up; steps S3-S5 are repeated until each section of the primary fracturing crack is plugged; the first-stage oil pipe is the oil pipe that is lowered into the formation into the first-stage drillable intubation packer belt;

[0051] The resin plugging agent used in step S5 is composed of a main agent and a curing agent, wherein the main agent is a mixture of phenolic resin and urea-formaldehyde resin in a volume ratio of 1:1.3, and the curing agent is 0.15% methyl ethyl ketone peroxide; in an exemplary embodiment of the present invention, the amount of injected plugging agent is 2 cubic meters; the displacement amount is the volume of the first-stage oil pipe at the top of the first-stage drillable intubation packer, that is, the amount of clean water used to push the resin plugging agent from the wellhead position to the target layer position of the wellbore, so as to achieve the resin plugging agent entering the crack and sealing.

[0052] A horizontal well chemical plugging wellbore reconstruction method proposed by the present invention also includes the following steps:

[0053] S6: After 48 hours of waiting, the horizontal wellbore is drilled and ground;

[0054] S7: After the wellbore pressure test reaches 50MPa and no problems are found, the bridge-shot continuous fracturing operation can be resumed.

[0055] The implementation process of the above method is described in detail below in conjunction with a specific embodiment, which specifically includes the following steps:

[0056] Step 1) pull out the horizontal well production string, clear the well to the artificial bottom, and inject a large amount of clean water for reverse circulation to wash the well until the water quality at the inlet and outlet is consistent;

[0057] Step 2) According to the current well produced fluid volume of 8375 cubic meters, in order to replenish the formation energy, before repeated fracturing, 7956 cubic meters of imbibition fluid with a formula of 0.3% ES-2 is injected into the formation in three sections, 2652 cubic meters in each section;

[0058] Energy replenishment string structure (from bottom to top): check valve + sandblaster + sleeve seat + K344 packer (position: 2620.0±1.0m) + sleeve sandblaster + Φ73mm chamfered tool tubing + sleeve seat + K344 packer (position: 2382.0±1.0m) + sleeve sandblaster + Φ73mm chamfered tool tubing + K344 packer (position: 2152.0±1.0m) + Φ73mm chamfered coupling tool tubing (20m above the inclination point) + Φ73mm tool tubing to the wellhead.

[0059] Step 3) Run the first-stage drillable intubation packer (2802 m) with the first-stage tubing, 2800 m above the first perforation section;

[0060] Step 4) using the first-stage oil pipe to inject 35 cubic meters of FL-1 gel into the primary fracturing crack, and adding 35 cubic meters of sand for the first stage of initial transformation;

[0061] Step 5) After the gel injection is completed, continue to inject 2 cubic meters of sealing resin plugging agent through the first-stage oil pipe to replace 8.4 cubic meters, pull out the oil pipe, backwash the oil pipe and then lift it up;

[0062] Step 6) The horizontal well is initially reformed in 9 sections, and steps 3-5 are repeated to complete the plugging of each fracture section;

[0063] Step 7) waiting for 48 hours;

[0064] Step 8) drilling and grinding the horizontal wellbore;

[0065] Step 9) testing the horizontal wellbore pressure to 50 MPa;

[0066] Step 10) Re-arrange the seams and carry out bridge-shot continuous fracturing construction.

[0067] The production curves before and after chemical plugging of the horizontal well in this embodiment are as follows: Figure 3 As shown in the figure, after plugging, the daily oil production and liquid production have increased significantly, while the water content has decreased. It can be seen that the horizontal well can be plugged by the horizontal well chemical plugging wellbore reconstruction method proposed in the present invention to achieve bridge-shot continuous volume fracturing construction, thereby solving the problems of low construction efficiency, pipe leakage and reduced casing size in repeated fracturing of horizontal wells.

[0068] Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent substitutions for some of the technical features therein; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A horizontal well chemical plugging wellbore reconstruction method, characterized in that: The following steps are involved: S1: The horizontal well production string is pulled out from the formation and passed to the bottom of the artificial well, and clean water is injected for reverse circulation to wash the well; S2: Inject imbibition fluid into the formation using the energy replenishment string until the formation pressure is restored to a level above 95%; S3: inserting a first-stage drillable intubation packer with a first-stage oil pipe into the formation; S4: injecting gel into the primary fracturing cracks using the first-stage oil pipe to fill the propped cracks; S5: After the gel is injected, a sealing resin plugging agent is injected through the first-stage oil pipe for displacement. After displacement, the first-stage oil pipe is pulled out and backwashed and then lifted up; steps S3-S5 are repeated until each section of the primary fracturing crack is plugged.

2. The horizontal well chemical plugging wellbore reconstruction method according to claim 1 is characterized in that: In step S1, the reverse circulation well is washed until the water quality of the water inlet and the water outlet are consistent after the oil pipe is backwashed.

3. The horizontal well chemical plugging wellbore reconstruction method according to claim 1 is characterized in that: In step S3, the first-stage drillable intubation packer is lowered to a position 2 m above the plugged perforation section.

4. The horizontal well chemical plugging wellbore reconstruction method according to claim 1, characterized in that: The method performs the following operations after completing the plugging of each primary fracturing fracture: The plugged fractures are allowed to solidify for 2-4 days, and the horizontal wellbore is drilled and ground; The treated horizontal wellbore is pressure tested, and bridge-shot fracturing construction is carried out after the pressure test is successful.

5. The horizontal well chemical plugging wellbore reconstruction method according to claim 1, characterized in that: In step S2, the injection volume of the imbibition fluid is 95% of the produced fluid volume of the well; The imbibition liquid is ES-2 imbibition agent with a mass fraction of 0.3%.

6. The horizontal well chemical plugging wellbore reconstruction method according to claim 1, characterized in that: In step S2, the energy-boosting string is provided in multiple sections from the bottom of the well to the wellhead, including: a bottom energy-boosting string and a middle energy-boosting string; Wherein, the bottommost energy supplement string includes a one-way valve close to the bottom of the well and a sandblaster connected to the one-way valve, and the sandblaster is connected to an end away from the bottom of the well; The intermediate section energy supplement pipe string is provided with multiple sections, and each intermediate section energy supplement pipe string includes a sliding sleeve seat, a packer and a sandblaster in sequence from the bottom of the well to the wellhead; Each energy-boosting string below the deflection point is installed using chamfered coupling tool tubing, and each energy-boosting string above the deflection point is installed using ordinary tool tubing.

7. The horizontal well chemical plugging wellbore reconstruction method according to claim 6, characterized in that: The packer is a K344 packer, the chamfered coupling tool tubing is a Φ73 mm chamfered coupling tool tubing, and the common tool tubing is a Φ73 mm tool tubing.

8. The horizontal well chemical plugging wellbore reconstruction method according to claim 1, characterized in that: In step S4, the gel is FL-1 gel, and the amount of gel used is the amount of proppant used for initial fracturing.

9. The horizontal well chemical plugging wellbore reconstruction method according to claim 1, characterized in that: In step S5, the resin plugging agent formula consists of a main agent and a curing agent; The main agent is phenolic resin and urea-formaldehyde resin in a volume ratio of 1:1.3, and the curing agent is 0.15% methyl ethyl ketone peroxide.

10. The horizontal well chemical plugging wellbore reconstruction method according to claim 1, characterized in that: In step S5, the displacement amount of the injected sealing resin plugging agent is the first-stage tubing inner volume above the first-stage drillable intubating packer.

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