A method for staged water shutoff of horizontal wells in heavy oil edge-bottom water reservoirs

Abstract

The present invention belongs to the field of oil well water plugging and discloses a staged water plugging method for horizontal wells in heavy oil reservoirs with edge-bottom water, comprising at least the following steps: Step 1, determining whether the water outlet position of the horizontal well is the toe or the heel; Step 2, injecting a granular water-absorbing gel plugging agent into the formation through the horizontal well; Step 3, if the water outlet position is at the toe, executing Step 4; if the water outlet position is at the heel, injecting a predetermined amount of liquid bridge plugging agent into the formation injected with the granular water-absorbing gel plugging agent through the horizontal well, and then executing Step 4; Step 4, injecting a heat-resistant high-strength inorganic sealing agent into the formation through the horizontal well; Step 5, if the water outlet position is at the toe, drilling and milling to the predetermined toe position and then circulating and washing the well; if the water outlet position is at the heel, drilling and milling to the artificial well bottom and then circulating and washing the well. After implementation, the present invention can effectively reduce the comprehensive water content of the horizontal well and increase crude oil production.

Description

Technical Field

[0001] The invention belongs to the field of oil well water plugging, and relates to a staged water plugging method for horizontal wells in heavy oil edge and bottom water reservoirs. Background Art

[0002] The Liaohe Oilfield primarily develops heavy oil. Horizontal wells for heavy oil, with their advantages of long production sections, large drainage areas, and high controlled reserves, have become a key focus for increasing reserve utilization and play a key role in Liaohe's current and future stable production of tens of millions of tons. During the production of edge and bottom water reservoirs using horizontal wells, due to production pressure differentials and uneven recovery rates, the resulting pressure drop around the wellbore causes the oil-water interface to deform into a conical upward shape, leading to edge or bottom water seepage and flooding of the well. Water plugging technology for heavy oil horizontal wells presents two difficulties: First, due to the high viscosity of crude oil, water detection techniques cannot be implemented, and unclear water locations result in a low water plugging success rate; second, because most horizontal wells utilize screen completions, the plugging agent must be both injectable and retainable.

[0003] Currently, the predominantly used water-blocking methods, including single-stage plugging, two-stage plugging, and multi-stage plugging, lack specificity. The main plugging agents used are foams, high-temperature organic gels, and gel granules, though high-temperature organic gels are relatively expensive. Gel granules cannot be injected deep into the formation, and foam plugging agents exhibit insufficient sealing strength. Therefore, developing a staged water-blocking method for horizontal wells in heavy oil reservoirs with marginal and bottom water is imperative. Summary of the Invention

[0004] To overcome two major difficulties in existing technologies, the present invention provides a staged water plugging method for horizontal wells in heavy oil reservoirs with edge and bottom water, achieving the goal of stabilizing oil production and controlling water flow in horizontal wells. This method is particularly suitable for heavy oil steam huff-and-puff development of horizontal wells, effectively ensuring reserve utilization in water-producing heavy oil horizontal wells. It provides technical support for the deployment and development of future horizontal wells and the conversion of methods, and has broad application prospects.

[0005] The above-mentioned object of the present invention is achieved through the following technical solutions:

[0006] A staged water plugging method for a horizontal well in a heavy oil reservoir with edge and bottom water, wherein the water plugging method at least comprises:

[0007] Step 1: Determine whether the water outlet position of the horizontal well is the toe or heel through geological dynamic analysis, selective injection and production effects, well temperature test curves, etc.

[0008] Step 2: injecting granular water-absorbing gel plugging agent into the formation through a horizontal well to effectively block the dominant water flow channel;

[0009] Step 3: If the water outlet is at the toe, then execute step 4; if the water outlet is at the heel, then inject a predetermined amount of liquid temporary bridge plugging agent into the formation into which the granular water-absorbing gel plugging agent has been injected through the horizontal well, and then execute step 4;

[0010] Step 4, injecting a heat-resistant and high-strength inorganic sealing agent into the formation through the horizontal well;

[0011] Step 5: If the water outlet is at the toe, drill and grind to the predetermined position of the toe and then circulate and wash the well; if the water outlet is at the heel, drill and grind to the bottom of the artificial well and then circulate and wash the well; thus completing the staged water plugging construction.

[0012] The above-mentioned method for staged water plugging of horizontal wells in heavy oil and bottom water reservoirs, wherein, in the step 1, the geological dynamic analysis mainly includes the reservoir profile, wellbore trajectory, water quality data, etc., which can be used to preliminarily determine the water outlet location, which serves as condition I; the injection and production effect is the production effect after the injection and production measures are taken in each production cycle. If the injection and production effect is good, it is judged that the toe is producing water, otherwise it is judged that the heel is producing water, which serves as condition II; the well temperature test curve is a curve formed by the well temperature of the horizontal well tested after the end of each production cycle. If the continuous test shows that the toe temperature is high, it is judged that the toe is producing water, otherwise it is judged that the heel is producing water, which serves as condition III; if two or more conditions are met, the water outlet location can be determined.

[0013] In the aforementioned horizontal well segmented water plugging method for heavy oil reservoirs with edge and bottom water, step 3 further includes: after injecting the granular hydrogel plugging agent, closing the horizontal well to wait for setting, and after waiting for setting, performing a circulating well flushing operation on the entire section of the horizontal well. After the well flushing operation, if the water outflow point is at the toe, step 4 is executed; if the water outflow point is at the heel, the liquid bridge plugging agent is injected, the horizontal well is closed again to wait for setting, and after waiting for setting, the horizontal well is subjected to a second circulating well flushing operation, and finally step 4 is executed again.

[0014] In the above-mentioned staged water plugging method for horizontal wells in heavy oil reservoirs with edge and bottom water, in step 5, the predetermined toe position refers to the starting position of the toe water outlet determined according to step 1.

[0015] The above-mentioned staged water plugging method for horizontal wells in heavy oil reservoirs with edge and bottom water, wherein in step 2, the granular water-absorbing gel plugging agent is composed, by weight percentage, of 8-15% polyvinyl alcohol solution, 0.3-0.6% sodium tetraborate cross-linking agent, 1-3% water-based polyurethane reinforcing agent, 1-5% rubber powder solid phase particles, 1%-2% dodecyltrimethylammonium chloride drainage aid, and the balance is water.

[0016] The above-mentioned horizontal well segmented water plugging method for heavy oil edge and bottom water reservoirs, wherein in step 2, the injection amount of the granular water-absorbing gel plugging agent is 900-1300m 3 When injected, the displacement of the granular water-absorbing gel plugging agent is 30-35m 3 / h, the construction pressure is 14-19MPa.

[0017] The above-mentioned staged water plugging method for horizontal wells in heavy oil reservoirs with edge and bottom water, wherein in step 3, the liquid bridge plug temporary plugging agent is composed, by weight percentage, of 15-35% acrylamide monomer, 0.1-0.3% organic chromium cross-linking agent, 0.1-0.2% sodium bisulfite activator, 0.05-0.1% tetramethylethylenediammonium catalyst, and the balance is water.

[0018] The above-mentioned horizontal well segmented water plugging method for heavy oil edge and bottom water reservoirs, wherein in step 3, the injection amount of the liquid bridge plug temporary plugging agent is 8-20m 3 The specific amount is calculated based on the plugging position and wellbore volume.

[0019] The above-described method for staged water plugging in a horizontal well in a heavy oil reservoir with edge-bottom water, wherein in step 4, the heat-resistant, high-strength inorganic sealant is composed, by weight percentage, of 20-25% calcium / iron / silicon / magnesium oxides, 8-10% organic bentonite, 3-5% fly ash, 0.5-1% sodium carbonate triethanolamine, 0.05-0.1% sodium silicate, and the balance water. The calcium / iron / silicon / magnesium oxides are one or more combinations of tricalcium silicate, dicalcium silicate, forsterite, forsterite, and calcium aluminoferrite.

[0020] The above-mentioned horizontal well segmented water plugging method for heavy oil edge and bottom water reservoirs, wherein in step 4, the injection amount of the heat-resistant high-strength inorganic sealing agent is 150-300m 3 When injected, the displacement of the heat-resistant high-strength inorganic sealant is 18-25m 3 / h, construction pressure 9-12MPa.

[0021] The beneficial effects of the present invention compared with the prior art are:

[0022] This invention uses a heat-resistant, high-strength inorganic sealant, injected in liquid form, that can pass smoothly through the perforations of horizontal well screens without accumulation. Compared to similar plugging agents domestically and internationally, it exhibits selective plugging properties, achieving a diversion rate difference of over 90% between high- and low-permeability zones, effectively blocking larger permeabilities without contaminating smaller ones. This facilitates access to the outlet channel without contaminating the oil layer. It also reacts and solidifies at temperatures above 80°C, ensuring a safe and controllable construction process. Its temperature resistance can reach over 350°C, meeting the high-temperature requirements of steam stimulation development for heavy oil horizontal wells.

[0023] This invention develops a method for finding water in heavy oil horizontal wells to initially determine the location of water production, providing a basis for targeted subsequent water plugging operations. A chemical staged water plugging process is then employed for horizontal wells with different water production locations. This technology, when implemented, can effectively reduce the overall water content of horizontal wells and increase crude oil production.

[0024] The method for finding water in heavy oil horizontal wells has solved the problem of difficulty in testing and finding water due to the heavy oil, achieving a technological breakthrough; for horizontal wells with clear water outlet locations, a chemical staged water plugging process has been developed to improve the targetedness and effectiveness of water plugging. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present invention will be further described below with reference to the accompanying drawings and examples.

[0026] Attachment Figure 1 This is a schematic diagram of the method for finding water in heavy oil horizontal wells. DETAILED DESCRIPTION

[0027] To provide a clearer understanding of the technical features, objectives, and beneficial effects of the present invention, the technical solutions of the present invention are described in detail below with reference to the following specific examples. However, these examples are not to be construed as limiting the scope of the present invention. Unless otherwise specified, the experimental methods employed in the present invention are conventional methods, and the experimental equipment, materials, and reagents used are all commercially available.

[0028] Example 1

[0029] This embodiment provides a staged water plugging method for a horizontal well in a heavy oil reservoir with edge and bottom water. The method uses the Du 32-Xing H452 well in the Liaohe Oilfield as a research object and performs staged water plugging on the horizontal well. The operation steps are as follows:

[0030] Step 1: Through geological dynamic analysis, injection and production effects, well temperature test curves, etc., it is determined that the water outlet position of the horizontal well is 1390m-1507m.

[0031] The specific judgment basis is as follows: (1) The water quality of the well is 1800-2100 mg / L, which is consistent with the bottom water quality of the block; the reservoir profile and wellbore trajectory show that 1390m-1507m is 4-5m away from the bottom of the oil layer, and 1240m-1390m is 5-15m away from the bottom of the oil layer. The initial judgment is that the water-producing position is between 1390m-1507m, which is used as condition I; (2) The effect of the injection and production of the toe of 1390m-1507m in the 2-3 cycles of the well is poor, and the effect of the injection and production of the toe of 1240m-1390m in the 4-6 cycles is good. Therefore, it is judged that water is produced at the toe of 1390m-1507m, which is used as condition II; (3) The horizontal well temperature test curve shows that the temperature of the toe of 1390m-1507m is high in the 2-6 cycle continuous test. It is again judged that water is produced at the toe, which is used as condition III;

[0032] Step 2: Inject granular hydrogel plugging agent into the formation through the horizontal well to effectively block the dominant water flow channel. During injection, the injection volume of granular hydrogel plugging agent is 1250m 3 , injection displacement is 30m 3 / h, with an application pressure of 18MPa. The raw materials for the granular water-absorbing gel plugging agent, calculated by mass percentage, include 13% polyvinyl alcohol solution, 0.5% sodium tetraborate crosslinker, 2.5% water-based polyurethane enhancer, 3.5% rubber powder solid particles, 1.5% dodecyltrimethylammonium chloride drainage aid, and the balance water.

[0033] Step 3: Close the horizontal well and wait for setting for 24 hours, then perform circulation flushing on the entire section of the horizontal well.

[0034] Step 4: Inject high-strength, heat-resistant inorganic sealant into the formation through the horizontal well to resist subsequent high-temperature steam erosion, protect the granular water-absorbing gel plugging agent, and extend the effective period of water plugging measures. During injection, the injection volume of the high-strength, heat-resistant inorganic sealant is 280m 3 , injection displacement is 20m 3 / h, with a construction pressure of 12MPa. The raw materials for the heat-resistant, high-strength inorganic sealant, calculated by mass percentage, include 23.5% solid solution of dicalcium silicate, calcium forsterite, and calcium forster rhodonite, 9% organic bentonite, 3.5% fly ash, 0.8% sodium carbonate triethanolamine, 0.09% sodium silicate, and the balance water.

[0035] Step 5: Use the minor drilling and washing tool to drill to the predetermined toe position of 1390m, lift the tubing string to 900m, and then perform circulating well washing to complete the staged water plugging construction.

[0036] Example 2

[0037] This embodiment provides a staged water plugging method for a horizontal well in a heavy oil reservoir with edge and bottom water. The method uses the Du 32-Xing H451 well in the Liaohe Oilfield as a research object and performs staged water plugging on the well. The operation steps are as follows:

[0038] Step 1: Through geological dynamic analysis, injection and production effects, well temperature test curves, etc., it is determined that the water outlet position of the horizontal well is 1290m-1410m.

[0039] The specific judgment is as follows: (1) The water quality of the well is 2000-2100 mg / L, which is consistent with the bottom water quality of the block; the reservoir profile and wellbore trajectory show that 1290m-1410m is 5-7m away from the bottom of the oil layer, and 1410m-1493m is 7-19m away from the bottom of the oil layer. The initial judgment is that the water-producing position is between 1290m-1410m, which is used as condition I; (2) The effect of the injection and production of the heel 1290m-1410m in the 4-6 cycles is poor, and the effect of the injection and production of the toe 1410m-1493m in the 7-8 cycles is good. Therefore, it is judged that water is produced at the heel 1290m-1410m, which is used as condition II; (3) The horizontal well temperature test curve shows that the temperature of the heel 1290m-1410m is high in the 4-8 cycle continuous test. It is again judged that water is produced at the heel, which is used as condition III;

[0040] Step 2: Inject the granular hydrogel plugging agent into the formation through the horizontal well to effectively block the dominant water flow channel. During injection, the injection volume of the granular hydrogel plugging agent is 1100m 3 , the injection displacement is 31m 3 / h, with an application pressure of 16MPa. The raw materials for the granular water-absorbing gel plugging agent, calculated by mass percentage, include 15% polyvinyl alcohol solution, 0.6% sodium tetraborate crosslinking agent, 2% water-based polyurethane reinforcing agent, 3% rubber powder solid particles, 1% dodecyltrimethylammonium chloride drainage aid, and the balance water.

[0041] Step 3: Close the horizontal well and wait for setting for 24 hours, then perform circulation flushing on the entire section of the horizontal well.

[0042] After the well is flushed, a liquid bridge plugging agent is injected into the formation through the horizontal well to temporarily protect the non-blocking layer. During the injection, the injection volume of the liquid bridge plugging agent is 15m 3 , wherein, by mass percentage, the raw material composition of the liquid bridge plug temporary plugging agent includes 25% acrylamide monomer, 0.2% organic chromium cross-linking agent, 0.15% sodium bisulfite, 0.08% tetramethylethylenediammonium, and the balance is water.

[0043] After the liquid bridge plug temporary plugging agent was injected, the original pipe string was probed to 1410m and encountered resistance, confirming that the plug position in the wellbore was normal; the horizontal well was closed again to wait for setting for 24 hours, and the horizontal well 1290m-1410m was circulated and flushed.

[0044] Step 4: Inject high-strength, heat-resistant inorganic sealant into the formation through the horizontal well to resist subsequent high-temperature steam erosion and protect the granular water-absorbing gel plugging agent. During injection, the injection volume of the high-strength, heat-resistant inorganic sealant is 200m 3 , injection displacement is 18m 3 / h, and the construction pressure is 10MPa. The raw materials of the heat-resistant and high-strength inorganic sealant, calculated by mass percentage, include 20% solid solution of tricalcium silicate, calcium aluminoferrite, and calcium magnesium rhodonite, 8% organic bentonite, 3% fly ash, 0.6% sodium carbonate triethanolamine, 0.06% sodium silicate, and the balance is water.

[0045] Step 5: Use minor drilling and washing tools to drill, grind and circulate the well to the artificial well bottom of 1493m to complete the staged water plugging construction.

[0046] The above-described embodiments are only preferred embodiments of the present invention, and are not intended to be all feasible embodiments of the present invention. Any obvious modifications made by a person skilled in the art without departing from the principles and spirit of the present invention should be considered to be included within the scope of protection of the claims of the present invention.

Claims

1. A staged water plugging method for horizontal wells in heavy oil reservoirs with edge and bottom water, characterized in that: The water blocking method comprises at least the following steps: Step (1) is to determine whether the water-producing position of the horizontal well is the toe or the heel through geological dynamic analysis, injection and production effects, and well temperature test curves; the geological dynamic analysis includes reservoir profiles, wellbore trajectories, and water-quality data; the injection and production effects are the production effects after injection and production measures are taken in each production cycle. If the injection and production effect is good, it is determined that the toe is producing water, otherwise it is determined that the heel is producing water; the well temperature test curve is a curve formed by the horizontal well temperature tested after each production cycle. If the continuous test shows that the toe temperature is high, it is determined that the toe is producing water, otherwise it is determined that the heel is producing water; Step (2), injecting a granular water-absorbing gel plugging agent into the formation through a horizontal well to effectively block the dominant water flow channel; In step (3), if the water outlet position is at the toe, step (4) is executed; if the water outlet position is at the heel, a predetermined amount of liquid bridge plugging agent is injected into the formation into which the granular hydrophilic gel plugging agent has been injected through the horizontal well, and then step (4) is executed; after the granular hydrophilic gel plugging agent is injected, the horizontal well is closed to wait for setting, and after the waiting for setting is completed, the entire well section of the horizontal well is circulated and washed, and after the well washing is completed, if the water outlet position is at the toe, step (4) is executed; if the water outlet position is at the heel, the liquid bridge plugging agent is injected, and then the horizontal well is closed to wait for setting again, and after the waiting for setting is completed, the horizontal well is circulated and washed twice, and finally step (4) is executed; Step (4), injecting a heat-resistant and high-strength inorganic sealing agent into the formation through the horizontal well; Step (5): if the water outlet position is at the toe, the well is circulated and washed after drilling and grinding to the predetermined position of the toe; if the water outlet position is at the heel, the well is circulated and washed after drilling and grinding to the bottom of the artificial well; thereby completing the segmented water plugging construction; the predetermined toe position refers to the starting position of the toe water outlet determined according to step (1).

2. A staged water plugging method for horizontal wells in heavy oil edge and bottom water reservoirs according to claim 1, characterized in that: In step (2), the granular water-absorbing gel plugging agent is composed of the following components by mass percentage: 8-15% of polyvinyl alcohol solution, 0.3-0.6% of sodium tetraborate crosslinking agent, 1-3% of water-based polyurethane reinforcing agent, 1-5% of rubber powder solid phase particles, 1%-2% of dodecyltrimethylammonium chloride drainage aid, and the balance is water.

3. The method for staged water plugging in a horizontal well of a heavy oil reservoir with edge and bottom water according to claim 1, wherein: In step (2), the injection amount of the granular water-absorbing gel plugging agent is 900-1300m 3 When injected, the displacement of the granular water-absorbing gel plugging agent is 30-35m 3 / h, the construction pressure is 14-19MPa.

4. The method for staged water plugging of a horizontal well in a heavy oil reservoir with edge and bottom water according to claim 1, wherein: In step (3), the liquid bridge plugging agent is composed of the following components by mass percentage: 15-35% acrylamide monomer, 0.1-0.3% organic chromium crosslinking agent, 0.1-0.2% sodium bisulfite activator, 0.05-0.1% tetramethylethylenediammonium catalyst, and the balance is water.

5. The method for staged water plugging in a horizontal well of a heavy oil reservoir with edge and bottom water according to claim 1, wherein: In step (3), the injection volume of the liquid bridge plugging agent is 8-20m 3 .

6. The method for staged water plugging of a horizontal well in a heavy oil reservoir with edge and bottom water according to claim 1, wherein: In step (4), the heat-resistant and high-strength inorganic sealant is composed of the following components by mass percentage: 20-25% of calcium / iron / silicon / magnesium oxides, 8-10% of organic bentonite, 3-5% of fly ash, 0.5-1% of sodium carbonate triethanolamine, 0.05-0.1% of sodium silicate, and the balance is water.

7. A staged water plugging method for horizontal wells in heavy oil edge and bottom water reservoirs according to claim 6, characterized in that: The calcium / iron / silicon / magnesium oxides refer to one or more combinations of tricalcium silicate, dicalcium silicate, forsterite, rhodonite, and calcium aluminoferrite.

8. The method for staged water plugging of horizontal wells in heavy oil edge and bottom water reservoirs according to claim 1, characterized in that: In step (4), the injection amount of the heat-resistant high-strength inorganic sealant is 150-300m 3 When injected, the displacement of the heat-resistant high-strength inorganic sealant is 18-25m 3 / h, construction pressure 9-12MPa.

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