Non-hydrocarbon gas auxiliary thermal recovery dual anti-channeling process

Abstract

The invention belongs to the technical field of channeling prevention in oilfield exploitation, and discloses a non-hydrocarbon gas assisted thermal recovery'dual 'channeling prevention process, which is characterized in that a'high-strength temporary plugging agent' system is injected at the front end, and the system is prepared from the following components in percentage by mass: 0.6 to 0.8 percent of gelling agent, 0.1 to 0.2 percent of cross-linking agent, 0.05 to 0.2 percent of retardant and the balance of water; a high-strength plugging agent system is injected into the rear end, and the system is prepared from, by mass, 0.4%-0.6% of a curing agent, 5%-6% of a high-temperature-resistant plugging agent, 0.3%-0.5% of a foaming agent, 0.1%-0.2% of polyacrylamide and the balance water. The method is reasonable in design and reliable in basis, has the functions of profile control and gas channeling inhibition, gas injection quantity increase, steam channeling influence reduction and the like compared with a conventional independent non-hydrocarbon gas assisted steam huff and puff technology, and provides an effective method for solving the double channeling problems of gas channeling and steam channeling in non-hydrocarbon gas assisted steam huff and puff.

Description

Technical Field

[0001] This invention belongs to the field of oilfield development anti-channeling technology, and relates to a "dual" anti-channeling process for non-hydrocarbon gas-assisted thermal recovery. Specifically, it relates to a process method for temporarily plugging the front end to prevent non-hydrocarbon gas from channeling during the non-hydrocarbon gas-assisted steam injection process, which would prevent the normal completion of construction, while simultaneously sealing the end to reduce the impact of steam channeling on the non-hydrocarbon gas-assisted injection effect. Background Technology

[0002] The Shuguang Oilfield's heavy and extra-heavy oil reservoirs are developed using steam huff and puff, a depressurization extraction method. With increasing huff and puff cycles, formation pressure gradually decreases from 10-13 MPa in the initial stages to 1-2 MPa in the later stages, resulting in severe formation energy deficiency. Cycle production has dropped from a peak of 1500-2000 tons to an average of 200-400 tons per 25 cycles. Non-hydrocarbon gas-assisted steam huff and puff technology is an effective means to improve this situation. In recent years, the Shuguang Oilfield has implemented nitrogen and CO2 non-hydrocarbon gas-assisted huff and puff technologies in over 200 wells annually, increasing oil production by more than 28,000 tons per year, effectively supplementing formation energy and significantly improving cycle production. In particular, the large-scale implementation of electrically driven nitrogen-assisted steam huff and puff has greatly improved the production benefits of non-hydrocarbon gas-assisted steam huff and puff measures, showing broad prospects for widespread application.

[0003] However, due to the inherent characteristics of heavy and extra-heavy oil reservoirs—high porosity, high permeability, and inter-layer differences—coupled with an increased number of steam huff and puff cycles (averaging 25 cycles), the inter-layer differences are bound to widen further as high-permeability layers are extracted, leading to more widespread non-hydrocarbon gas channeling and steam channeling. Gas channeling prevents non-hydrocarbon gas-assisted steam huff and puff measures from injecting the designed quantities as planned; steam channeling results in poorer energy overflow huff and puffing performance in the well or forces well shutdown due to channeling, impacting production efficiency. Therefore, it is urgent to research a method to address both upstream gas channeling and downstream steam channeling, achieving a "dual" anti-channeling effect with non-hydrocarbon gas-assisted steam huff and puff, improving the success rate of measures, enhancing reservoir utilization, and significantly improving the steam huff and puffing effect for heavy oil.

[0004] CN117143288A discloses a method for preparing an in-situ polymerized gel plugging agent for CO2-driven oil displacement and gas channeling prevention; CN115725017A discloses a high-temperature gas channeling prevention polymer, its preparation method and application; CN115073508A discloses a pH-responsive gas channeling prevention plugging agent, its preparation and application; CN114989796A discloses a gas channeling prevention system and its application; CN109267977A discloses a two-stage gas channeling prevention and carbon dioxide-driven gas channeling prevention process, experimental apparatus and method; CN108516756A discloses a high-temperature resistant gas channeling prevention cement system and its preparation method.

[0005] The March 2016 issue of "Advances in Fine Petrochemicals" published an article on the research and field application of non-hydrocarbon gas-assisted huff and puff technology, which disclosed the injection method of nitrogen foam + carbon dioxide + steam. The January 2018 issue of "Petroleum Drilling and Production Technology" published an article on the research status and development direction of gas-assisted steam huff and puff in heavy oil reservoirs, which disclosed auxiliary steam huff and puff technologies such as nitrogen, CO2, flue gas, and foam.

[0006] The gas channeling prevention methods mentioned in the aforementioned patents and articles involve the use of polymeric gel plugging agents, gas channeling prevention polymers, pH-responsive gas channeling prevention plugging agents, etc., which have problems such as limited anti-channeling capabilities or complex construction processes. Summary of the Invention

[0007] To overcome the shortcomings of existing technologies, the purpose of this invention is to provide a technically feasible, simple to construct, and effective "dual" anti-channeling process for non-hydrocarbon gas-assisted steam huff and puff. The "dual" anti-channeling process for non-hydrocarbon gas-assisted steam huff and puff described in this invention is an innovative process designed to prevent both gas and steam channeling, which can greatly improve the success rate and effectiveness of non-hydrocarbon gas-assisted steam huff and puff construction.

[0008] The technical solution of the process method provided by this invention is as follows:

[0009] A non-hydrocarbon gas-assisted thermal recovery "dual" anti-channeling process includes the following steps:

[0010] (1) Front-end “high-strength temporary plugging”: The front-end is injected with a “high-strength temporary plugging agent” system, which consists of 0.6-0.8% gelling agent + 0.1-0.2% crosslinking agent + 0.05-0.2% retarder + the balance water;

[0011] (2) Back-end “high-strength sealing”: The back-end is injected with a “high-strength sealing agent” system, which consists of 0.4-0.6% curing agent + 5-6% high-temperature resistant sealing agent + 0.3-0.5% foaming agent + 0.1-0.2% polyacrylamide + the balance water.

[0012] Furthermore, in step (1), the gelling agent is composed of one or more of modified guar gum, konjac gum, and polyacrylamide;

[0013] Furthermore, in step (1), the crosslinking agent is composed of one or more of organic boron and borax;

[0014] Furthermore, the retardant in step (1) is composed of one or more of hydroxycarboxylic acids, aminocarboxylic acids, citric acid, and gluconic acid.

[0015] Furthermore, in step (1), the injection volume of the "high-strength temporary plugging agent" system is based on the change in injection pressure, that is, according to the normal injection discharge rate of non-hydrocarbon gas, which is 800-1200 Nm. 3 / h, through stratified injection testing, the injection pressure of the high-permeability layer is P1, and the injection pressure of the low-permeability layer is P2. The injection volume of the high-strength temporary plugging agent is gradually increased from 10 cubic meters, 15 cubic meters, 20 cubic meters... until the injection pressure reaches P. At the same time, the injection pressure of the high-strength temporary plugging agent is also taken into account, considering the pressure difference between the gas and liquid phases.

[0016] When P = P2 - (H / 1000 × 10 - H / 1000 × 3.3), then the injection stops;

[0017] Wherein, P2 represents the injection pressure of the low-permeability layer, in MPa;

[0018] P - Injection pressure of high-strength temporary plugging agent, in MPa;

[0019] H - Oil layer depth, in meters (m).

[0020] Furthermore, the curing agent in step (2) is composed of one or more of phenolic resin, aryl ether ester diarylamine, hydrogenated methyl nadic anhydride, polyether amine, and thiol amine;

[0021] Furthermore, the high-temperature resistant plugging agent in step (2) is composed of one or more of epoxy resin, silicone resin, polyimide, and polytetrafluoroethylene;

[0022] Furthermore, the foaming agent in step (2) is composed of one or more of sodium alkylbenzene sulfonate, sodium α-alkenyl sulfonate, dodecyl dimethylamine oxide, and dodecyl dimethyl betaine.

[0023] Furthermore, in step (2), the injection volume of the "high-strength plugging agent" system is determined according to the cylinder volume formula Q = πR. 2 hΦ is calculated, where Q is the injection volume, in meters. 3 π is the constant of pi, taken as 3.14; R is the sealing radius, ranging from 1.5 to 2.0, in meters; h is the oil layer thickness, in meters; Φ is the oil layer porosity, in μm. 2 .

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] This invention is reasonably designed and based on reliable principles. Compared with previous non-hydrocarbon gas-assisted steam huff and puff technologies, it has functions such as profile control to suppress gas channeling, increase the amount of injected gas, and reduce the impact of steam channeling. It provides an effective method to solve the problem of "double" channeling of gas channeling and steam channeling in non-hydrocarbon gas-assisted steam huff and puff. Detailed Implementation

[0026] The present invention is described in detail below through specific embodiments, but this does not limit the scope of protection of the present invention. Unless otherwise specified, the experimental methods used in the present invention are all conventional methods, and the experimental equipment, materials, reagents, etc. used can all be obtained commercially.

[0027] A "high-intensity temporary plugging" measure is implemented at the front end before the implementation of non-hydrocarbon gas-assisted steam huff and puff, and a "high-intensity sealing" measure is implemented at the end after the implementation of non-hydrocarbon gas-assisted steam huff and puff. The combination of "temporary plugging" and "sealing" not only prevents the leakage and spillage of non-hydrocarbon gas, but also prevents the leakage and impact of steam. This ensures the normal implementation of non-hydrocarbon gas-assisted steam huff and puff, and also ensures that the steam huff and puff effect is not affected.

[0028] First, a "high-strength temporary plugging agent" is injected into the oil layer, followed by non-hydrocarbon gas. When the expected injection volume is reached, another "high-strength sealing agent" is injected simultaneously with nitrogen. After the plugging agent solidifies, steam is then injected. The initial "high-strength temporary plugging agent" functions as a temporary plugging agent, ensuring that non-hydrocarbon gas does not cross-flow between wells. Simultaneously, it acts as a profile control agent, forcing non-hydrocarbon gas to diffuse into low-permeability layers, thus improving reservoir recovery. The final "high-strength sealing agent" functions as a sealing agent and possesses high-temperature resistance, ensuring that the injected steam does not cross-flow during subsequent steam injection, thereby improving steam thermal efficiency.

[0029] The implementation steps of this non-hydrocarbon gas-assisted steam huff and puff "dual" anti-channeling process are as follows:

[0030] 1. Front-end "high-strength temporary plugging": The front-end "high-strength temporary plugging agent" plays a temporary plugging function to ensure that non-hydrocarbon gas does not flow between wells. At the same time, it plays a profile control role, forcing non-hydrocarbon gas to diffuse to low-permeability layers and improving reservoir utilization.

[0031] The system consists of 0.6-0.8% gelling agent, 0.1-0.2% crosslinking agent, 0.05-0.2% retarder, and the balance water.

[0032] The gelling agent is composed of one or more of modified guar gum, konjac gum, and polyacrylamide; the crosslinking agent is composed of one or more of organic boron and borax; and the retarder is composed of one or more of hydroxycarboxylic acid, aminocarboxylic acid, citric acid, and gluconic acid.

[0033] The injection volume is based on changes in injection pressure, specifically a normal non-hydrocarbon gas injection discharge rate of 800-1200 Nm³. 3 / h, through stratified injection testing, the injection pressure of the high-permeability layer is P1, and the injection pressure of the low-permeability layer is P2. The injection volume of the high-strength temporary plugging agent is gradually increased from 10 cubic meters, 15 cubic meters, 20 cubic meters... until the injection pressure reaches P. At the same time, the injection pressure of the high-strength temporary plugging agent is also taken into account, considering the pressure difference between the gas and liquid phases.

[0034] When P = P2 - (H / 1000 × 10 - H / 1000 × 3.3), the injection stops.

[0035] Wherein, P2 represents the injection pressure of the low-permeability layer, in MPa;

[0036] Q - Injection pressure of high-strength temporary plugging agent, in MPa;

[0037] H - Oil layer depth, in meters (m).

[0038] 2. High-strength plugging at the back end: The high-strength plugging agent at the back end performs the plugging function and has high temperature resistance to ensure that the injected steam does not "steam channeling" during the subsequent steam huff and puff process, thereby improving the steam thermal efficiency.

[0039] The system consists of 0.4-0.6% curing agent, 5-6% high-temperature resistant sealant, 0.3-0.5% foaming agent, 0.1-0.2% polyacrylamide, and the balance water.

[0040] The curing agent is composed of one or more of phenolic resin, aryl ether ester diarylamine, hydrogenated methyl nadic anhydride, polyetheramine, thiolamine, etc.; the high-temperature resistant sealing agent is composed of one or more of epoxy resin, organosilicon resin, polyimide, polytetrafluoroethylene, etc.; and the foaming agent is composed of one or more of alkylbenzene sulfonate, α-alkenyl sulfonate, dodecyl dimethylamine oxide, dodecyl dimethyl betaine, etc.

[0041] The injection volume is calculated according to the cylinder volume formula Q = πR 2 hΦ, Q is the injection volume, in meters. 3 π is the constant of pi, taken as 3.14; R is the sealing radius, ranging from 1.5 to 2.0, in meters; h is the oil layer thickness, in meters; Φ is the oil layer porosity, in μm. 2 Injection volume: 30-60 mg / L 2 It is injected synchronously with nitrogen, and the pumping pressure is controlled below 15 MPa.

[0042] Example 1

[0043] A dual anti-channeling technology for non-hydrocarbon gas-assisted steam huff and puff in well Du 212-33-279 of a certain oilfield. The design and construction followed the steps outlined above, including a front-end "high-strength temporary plugging" system: This system consists of 0.6-0.8% modified guar gum + 0.1-0.2% organoboron + 0.05-0.2% aminocarboxylic acid + the balance water.

[0044] The injection volume is based on changes in injection pressure, specifically a normal non-hydrocarbon gas injection discharge rate of 800-1200 Nm³. 3 / h, through layered injection tests, the injection pressure of the high-permeability layer is 2MPa, the injection pressure of the low-permeability layer is 8MPa, and when the injection volume of the high-strength temporary plugging agent is gradually increased from 10 cubic meters, 15 cubic meters, 20 cubic meters to 28 cubic meters, the injection pressure reaches P = P2 - (800 / 1000×10 - 800 / 1000×3.3) = 2.64MPa.

[0045] The wellbore is designed to inject 70,000 Nm³ of nitrogen using a non-hydrocarbon-assisted steam huff and puff scheme. 3 , after injecting 3Nm 3 Gas leakage occurred, forcing a shutdown of the injection system and failing to meet the design requirements. The system then transitioned to steam injection, with a designed steam injection volume of 2000 m³ / h. 3 Inject 1500m 3 At that time, steam leakage occurred, which forced the shutdown of well Du212-33-281. The steam heat utilization rate of this well also decreased accordingly due to steam leakage.

[0046] After implementing the above measures, the well's production cycle was 58 days, with a cycle oil production of 335 tons, an increase of only 45 tons compared to the previous round of conventional huff and puff. This well implemented a non-hydrocarbon-assisted steam huff and puff scheme this cycle, designed to inject 80,000 Nm³ of nitrogen. 3 No gas channeling occurred during the gas injection process, and the required gas injection volume was met. The process then proceeded to the steam huff and puff stage, with a designed steam injection volume of 2100 m³ / h. 3 No steam channeling occurred, and the steam injection effect was good. After the measures were implemented, the well produced oil for 78 days, with a cycle production of 516 tons, an increase of 181 tons compared to the previous non-hydrocarbon-assisted steam injection cycle.

[0047] Example 2

[0048] The Du 8133873 well in a certain oilfield employs a "dual" anti-channeling technology for non-hydrocarbon gas-assisted steam huff and puff. The design and construction follow the steps outlined above, including a front-end "high-strength temporary plugging" system composed of 0.6-0.8% konjac gum, 0.1-0.2% borax, 0.05-0.2% hydroxycarboxylic acid, and the remainder water.

[0049] The injection volume is based on changes in injection pressure, specifically a normal non-hydrocarbon gas injection discharge rate of 800-1200 Nm³. 3 / h, through layered injection tests, the injection pressure of the high-permeability layer is 3MPa, the injection pressure of the low-permeability layer is 10MPa, and when the injection volume of the high-strength temporary plugging agent is gradually increased from 10 cubic meters, 15 cubic meters, to 22 cubic meters, the injection pressure reaches P = P2 - (800 / 1000×10 - 800 / 1000×3.3) = 4.24MPa.

[0050] The wellbore periodically implements a non-hydrocarbon assisted steam huff and puff scheme, designed to inject 60,000 Nm³ of nitrogen. 3 After injecting 40,000 Nm 3Gas leakage occurred, forcing a shutdown of the injection system and failing to meet the design requirements. The system then transitioned to steam injection, with a designed steam injection volume of 1800 m³ / h. 3 Inject 1600m 3 At that time, steam leakage occurred, which forced the shutdown of well Du 8133875, which was affected by the leakage. The steam heat utilization rate of this well also decreased accordingly due to the steam leakage.

[0051] After implementing the above measures, the well's production cycle was 78 days, with a cycle oil production of 545 tons, an increase of only 76 tons compared to the previous round of conventional huff and puff. This well implemented a non-hydrocarbon-assisted steam huff and puff scheme this cycle, designed to inject 70,000 Nm³ of nitrogen. 3 No gas channeling occurred during the gas injection process, and the required gas injection volume was met. The process then proceeded to the steam huff and puff stage, with a designed steam injection volume of 1900 m³. 3 No steam channeling occurred, and the steam injection effect was good. After the measures were implemented, the well produced oil for 105 days per cycle, with a cycle production of 868 tons, an increase of 323 tons compared to the previous non-hydrocarbon-assisted steam injection cycle.

[0052] The embodiments described above are merely preferred embodiments of the present invention, and not all feasible embodiments of the present invention. Any obvious modifications made by those 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 non-hydrocarbon gas-assisted thermal recovery "dual" anti-channeling technology, characterized in that, Includes the following steps: (1) Front-end "high-strength temporary plugging": The front-end is injected with a "high-strength temporary plugging agent" system, which consists of 0.6-0.8% gelling agent + 0.1-0.2% crosslinking agent + 0.05-0.2% retarder + the balance water; (2) Back-end "high-strength sealing": The back-end is injected with a "high-strength sealing agent" system, which consists of 0.4-0.6% curing agent + 5-6% high-temperature resistant sealing agent + 0.3-0.5% foaming agent + 0.1-0.2% polyacrylamide + the balance water.

2. The non-hydrocarbon gas-assisted thermal recovery "dual" anti-channeling process according to claim 1, characterized in that, Step (1) The gelling agent is composed of one or more of the following: modified guar gum, konjac gum, and polyacrylamide.

3. The non-hydrocarbon gas-assisted thermal recovery "dual" anti-channeling process according to claim 1, characterized in that, Step (1) The crosslinking agent is a mixture of one or more of organic boron and borax.

4. The non-hydrocarbon gas-assisted thermal recovery "dual" anti-channeling process according to claim 1, characterized in that, Step (1) The retardant is composed of one or more of hydroxycarboxylic acid, aminocarboxylic acid, citric acid, and gluconic acid.

5. The non-hydrocarbon gas-assisted thermal recovery "dual" anti-channeling process according to claim 1, characterized in that, Step (1) The injection volume of the "high-strength temporary plugging agent" system is based on the change in injection pressure, that is, according to the normal injection discharge rate of non-hydrocarbon gas, 800-1200 Nm. 3 / h, through stratified injection testing, the injection pressure of the high-permeability layer is P1, and the injection pressure of the low-permeability layer is P2. The injection volume of the high-strength temporary plugging agent is gradually increased from 10 cubic meters, 15 cubic meters, 20 cubic meters... until the injection pressure reaches P. At the same time, the injection pressure of the high-strength temporary plugging agent is also taken into account, considering the pressure difference between the gas and liquid phases. When P = P2 - (H / 1000 × 10 - H / 1000 × 3.3), then the injection stops; Wherein, P2 represents the injection pressure of the low-permeability layer, in MPa; P - Injection pressure of high-strength temporary plugging agent, in MPa; H - Oil layer depth, in meters (m).

6. The non-hydrocarbon gas-assisted thermal recovery "dual" anti-channeling process according to claim 1, characterized in that, Step (2) The curing agent is composed of one or more of phenolic resin, aryl ether ester diarylamine, hydrogenated methyl nadic anhydride, polyether amine, and thiol amine.

7. The non-hydrocarbon gas-assisted thermal recovery "dual" anti-channeling process according to claim 1, characterized in that, Step (2) The high-temperature resistant sealant is composed of one or more of epoxy resin, silicone resin, polyimide, and polytetrafluoroethylene.

8. The non-hydrocarbon gas-assisted thermal recovery "dual" anti-channeling process according to claim 1, characterized in that, Step (2) The foaming agent is composed of one or more of sodium alkylbenzene sulfonate, sodium α-alkenyl sulfonate, dodecyl dimethylamine oxide, and dodecyl dimethyl betaine.

9. The non-hydrocarbon gas-assisted thermal recovery "dual" anti-channeling process according to claim 1, characterized in that, Step (2) The injection volume of the "high-strength plugging agent" system is determined according to the cylinder volume formula Q = πR. 2 hΦ is calculated, where Q is the injection volume, in meters. 3 π is the constant of pi, taken as 3.14; R is the sealing radius, ranging from 1.5 to 2.0, in meters; h is the oil layer thickness, in meters. Φ represents the porosity of the oil reservoir, in μm. 2 .