A precise channeling sealing method for steam drive high temperature channeling well

Abstract

The present application belongs to the field of oilfield development and enhanced oil recovery, and relates to a precise channeling sealing method for steam flooding high-temperature channeling wells. The method comprehensively analyzes the recent operation, production data and test data of the well, focuses on the well temperature test data, and applies the analysis method of "one look, two comparisons and three tests". The original well pipe column is pulled out, sand is flushed, the well is passed and leakage is checked. The well temperature curve is measured to verify the channeling layer position. The channeling sealing process is selected according to the channeling layer position. The channeling layer position absorption is measured. The agent is squeezed and injected. The displacement is replaced. The plug is drilled and the pressure is tested. The precise channeling sealing method for steam flooding high-temperature channeling wells is applied in the development process of heavy oil reservoir steam flooding. The channeling layer position of the high-temperature channeling production well is precisely sealed, the interwell channeling is effectively inhibited, the displacement effect of the non-channeling layer position is improved, the blocking agent has good temperature resistance, low water separation rate and high sealing rate, the measure has long effective period, and the development effect of the heavy oil reservoir steam flooding is effectively improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of oilfield development and enhanced oil recovery, and relates to a precise channeling sealing method for steam flooding high-temperature channeling wells, in particular to a method suitable for implementing steam flooding development in heavy oil reservoirs and sealing channeling in production wells corresponding to steam flooding to improve oil well production. BACKGROUND

[0002] After implementing steam flooding development in heavy oil reservoirs, four stages of thermal connection, displacement, breakthrough and denudation adjustment are generally experienced. Influenced by factors such as reservoir heterogeneity, few injection stages and unqualified injection, steam channeling channels will appear between injection and production wells, causing steam injected from the steam injection well to channel to the production well along the steam channeling channel, resulting in inefficient circulation of steam, reducing the steam utilization rate of steam flooding and affecting the development effect of steam flooding. In some cases, the steam channeling of the production well is serious, with a bottom hole temperature exceeding 250℃, and the production well shows obvious high-temperature, high-liquid and high-water characteristics.

[0003] For high-temperature channeling production wells, the field generally uses production well channeling sealing technology, that is, injecting and plugging agents into the steam channeling layer from the production well to force steam to displace crude oil from the non-steam channeling layer and improve oil well production. However, in actual application, on the one hand, the plugging agent is not selective, and on the other hand, the injection process is a general injection string, which cannot ensure that the agent accurately enters the steam channeling layer, and the agent may enter the non-steam channeling layer and cause pollution and blockage, affecting the effect of the measures. At the same time, the bottom hole temperature of the high-temperature channeling well in the middle and late stages of steam flooding development is greater than 250℃, and the plugging agent currently used in the field is a gel plugging agent or a cement plugging agent. The gel plugging agent has a temperature resistance of only 150℃, which cannot meet the technical requirements of high-temperature channeling sealing for high-temperature channeling wells, and the cement plugging agent has a temperature resistance close to 200℃, and the volume shrinkage rate after solidification reaches 12%, which cannot meet the technical requirements of high-temperature channeling sealing for high-temperature channeling wells. Therefore, for steam flooding high-temperature channeling wells, a precise channeling sealing technology and a matching plugging agent are urgently needed to achieve precise channeling sealing.

[0004] Through literature review and field research, the current authorized patents only involve methods of profile control or channeling sealing from steam injection wells, and there is no relevant information or patents on how to channel sealing at high temperature from steam channeling production wells and the corresponding precise channeling sealing process and method. SUMMARY

[0005] In order to solve the problems existing in the prior art, the present application studies and designs a method for precise channeling sealing for high-temperature channeling wells in the process of steam flooding development in heavy oil reservoirs, which clearly defines the steam channeling layer by technical means, designs the injection process and scheme to achieve precise channeling sealing, and designs and develops a high-temperature resistant plugging agent to implement precise channeling sealing for high-temperature channeling production wells, thereby improving the production effect of high-temperature channeling wells.

[0006] To achieve the above purpose, the present application provides the following technical solutions:

[0007] A precise channeling sealing method for steam drive high temperature channeling well, comprising the following steps:

[0008] (1) Comprehensive analysis of the recent operation, production data, test data of the well, focusing on well temperature test data, and applying the analysis method of "one look, two comparison, three test";

[0009] (2) Pull out the original well pipe column, explore sand, and check leakage;

[0010] (3) Measure the well temperature curve and verify the channeling layer;

[0011] (4) Select the channeling sealing process according to the channeling layer;

[0012] (5) Measure the channeling layer absorption: positive water injection, displacement 500L / min; Close the casing valve, measure the channeling layer absorption, the maximum pressure does not exceed 15MPa;

[0013] (6) Agent squeezing: positive water injection to fill the oil casing annulus, positive injection of blocking agent, displacement 500L / min, the maximum pressure during the squeezing process does not exceed 10MPa, if the pressure exceeds 10MPa, stop the construction immediately;

[0014] (7) Displacement: displacement of clean water, displacement 500L / min, the maximum pressure during the displacement process does not exceed 15MPa, if the pressure exceeds 15MPa, stop the displacement immediately; pressure diffusion for 10 minutes, tubing pressure to 0; reverse circulation well flushing, wash out the excess blocking agent, well flushing displacement not less than 500L / min, reverse water injection 1m 3 , the maximum pressure does not exceed 15MPa, the ash surface position is designed to be higher than the upper boundary of the oil layer by 150m;

[0015] (8) Drilling plug, pressure test: after closing the well for 72 hours, explore the ash surface, test pressure 15MPa, 30min pressure drop less than 0.5MPa is qualified, continue to drill plug and sand to the artificial bottom, large displacement reverse well flushing to the consistent water in and out, down the pump and open the well.

[0016] Further, the analysis method of "one look, two comparison, three test" is specifically:

[0017] (1) "One look": study the well temperature curve of high temperature channeling well, the well temperature data of high temperature channeling layer is obviously higher than that of non-channeling layer:

[0018] a) The well temperature of some layer in the production layer is obviously higher than that of other layers, which is judged as the channeling layer;

[0019] b) The well temperature high point is above the production layer, which means that there is a high temperature channeling layer above the production layer, which leads to high temperature channeling in the upper layer of the well, and the channeling layer is the obviously high temperature layer above the well.

[0020] (2) "two ratio": the well temperature curve of the high temperature gas channeling well is compared, the recent well temperature curve is compared and analyzed, the gas channeling time is determined according to the production characteristics of the well, and the corresponding relationship between the gas channeling time and the well temperature curve change is further determined;

[0021] a) if the gas channeling time of the well is between two well temperature tests, the analysis and judgment of the gas channeling layer are based on the following well temperature data;

[0022] b) if there is no well temperature data before and after the well channeling, the next operation well temperature data is analyzed to determine the gas channeling layer;

[0023] (3) "three tests": the well temperature of the high temperature gas channeling well is tested, the gas channeling layer is preliminarily determined through the analysis and judgment of the above two steps, and the well temperature data is further compared and analyzed to further determine the gas channeling layer.

[0024] Further, in the channeling sealing process, when the gas channeling layer is located in the upper part of the oil layer, the sand filling or ash plug process is designed, the distance from the bottom of the well is greater than 30m, the sand filling process is used, and the distance is less than 30m, the ash plug process is used, and the sand surface or ash surface is designed to be above the non-gas channeling layer 1-2m, which protects the non-gas channeling layer.

[0025] Further, in the channeling sealing process, when the gas channeling layer is located in the lower part of the oil layer, the drillable cement retainer + thickened tubing construction string is lowered, the cement retainer is seated in the non-gas channeling layer below 1-2m, the seat is qualified, the plugging agent is injected, and the upper non-gas channeling layer is protected.

[0026] Further, in the channeling sealing process, when the gas channeling layer is located in the middle part of the oil layer, the sand filling or ash plug process is designed, the distance from the bottom of the well is greater than 30m, the sand filling process is used, and the distance is less than 30m, the ash plug process is used, and the sand surface or ash surface is designed to be above the non-gas channeling layer 1-2m, which protects the lower non-gas channeling layer; the drillable cement retainer + thickened tubing construction string is lowered, the cement retainer is seated in the upper non-gas channeling layer below 1-2m, the seat is qualified, the plugging agent is injected, and the upper non-gas channeling layer is protected.

[0027] Further, the plugging agent is composed of inorganic non-metallic cementing agent, microcrystalline reinforcing agent, retarder, thixotropic agent and other additives.

[0028] Further, the inorganic non-metallic cementing agent is an industrial slag with a mass fraction of 72%.

[0029] Further, the microcrystalline reinforcing agent is active alumina powder with a mass fraction of 8%.

[0030] Further, the retarder is a borax / triethanolamine composite retarder with a mass fraction of 5%.

[0031] Further, the thixotropic agent is calcium bentonite, and the mass fraction is 5%.

[0032] Further, the ratio of the other auxiliary agent is 10%.

[0033] Technical index of high-temperature-resistant inorganic channeling sealing agent

[0034] Breakthrough pressure 1.53 MPa / cm Water production ≤0.8％ Temperature resistance 350℃ Shut-off ≥99％ Gel time 4-10 h adjustable

[0035] In the development of the above high-temperature-resistant inorganic channeling sealing agent, the following aspects are included:

[0036] (1) Design the sealing radius. If the steam channeling coefficient (the highest temperature of the steam channeling layer position / the average temperature of the oil layer) <1.5, the sealing radius is 1.5-2m; if the steam channeling coefficient is greater than or equal to 1.5, the sealing radius is 2-2.5m.

[0037] (2) Design the curing time. In combination with the construction time, the curing time is reduced under the premise of construction safety, so as to improve the sealing strength and ensure the sealing effect. The curing time is determined to be 4-6 hours.

[0038] (3) On-site liquid preparation design. When the plugging agent is prepared on site, the mass fraction of the plugging agent to the prepared water is (0.5-1):1, and the prepared water uses the sewage treated by the joint station at a temperature of not higher than 40 DEG C.

[0039] Compared with the prior art, the beneficial effects of the present application are:

[0040] The precise channeling sealing method of the steam flooding high-temperature steam channeling well can realize precise plugging of the steam channeling layer position of the high-temperature steam channeling production well, effectively inhibit the interwell steam channeling, improve the displacement effect of the non-steam channeling layer position, has good temperature resistance, low water separation rate, high plugging rate, long effective period of the plugging agent, and effectively improves the steam flooding development effect of the heavy oil reservoir. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical scheme and advantages of the present application more clear, the following will further describe the patent implementation manner of the present application. Unless otherwise specified, the experimental methods used in the present application are conventional methods, and the experimental apparatus, materials and reagents used can be obtained from commercial channels.

[0042] The present application is applied in a large number of high-temperature steam channeling production wells in the steam flooding development of a certain heavy oil reservoir, and good implementation effect is achieved, which is specifically realized as follows:

[0043] Example 1

[0044] This production well switched to steam drive production in 2011. The production formation ranges from 893.0 to 931.7 meters, comprising eight oil-bearing layers with a total thickness of 15.4 meters. Steam channeling began in August 2019, with an average daily fluid production of 27.8 cubic meters per second. 3 The well produces 1.2 tons of oil per day, with a wellhead temperature of 95℃ and a maximum formation temperature of 218.5℃ according to well temperature data. Previous attempts at general sealing techniques using gel-based plugging agents were ineffective. To improve the well's production level, a precise sealing method using steam-driven high-temperature steam-channeling was implemented.

[0045] This method is applied as follows:

[0046] Step 1: Conduct a comprehensive analysis of the well's recent operational and production data, as well as testing data, with a focus on well temperature testing data. Apply the analytical method of "observe, compare, and test." Comparing the well temperature data before and after steam leakage, the highest well temperature of 218.5℃ appeared at 897.0m after steam leakage, while before steam leakage, the temperature at this location was only 176.2℃. Analysis indicates that steam leakage occurred in this layer, specifically between 893.0-900.6m, a total of 4.8m.

[0047] Step Two: Well workover operations, including pulling in tubing, sand detection, well cleaning and leak testing, and logging temperature profiles. Data shows that the highest formation temperature is still at 897.0m, with a maximum temperature of 225.2℃. Based on the above data, the gas channeling zone is determined to be 893.0-900.6m, a total of 4.8m. The average oil layer temperature is 162.4℃, the gas channeling coefficient is 1.4, the designed sealing radius is 1.8m, and the reagent dosage is 23m³. 3 The curing time is 4 hours, and the specific gravity of the sealant solution is 1.8.

[0048] Step 3: Test the steam leakage absorption rate by injecting clean water at an injection pressure of 3 MPa. The result is 50 m³. 3 / h, meeting construction requirements. Fill the annulus with clean water and inject 23m of plugging agent. 3 Construction pressure: 8.6 MPa. Water extraction depth: 2.5 m. 3 Based on pressure changes, intermittent back-squeezing of clean water for 5.1m 3 The pressure was maintained until it reached 15 MPa, at which point the well was shut in and allowed to solidify for 72 hours.

[0049] Step 4: Probe the sand surface at 752.5m. Test the pressure at 15MPa. If the pressure drop is less than 0.5MPa after 30 minutes, the construction is qualified. Continue drilling and plugging to flush sand to the bottom of the artificial well. Backwash the well until the influent and effluent water are consistent, then lower the pump to open the well.

[0050] Implementation results:

[0051] After the implementation, the formation temperature of the original gas channeling layer of the production well dropped to 159.2℃, and the temperature of the non-gas channeling layer was 182.9℃, which indicated that the original gas channeling layer was effectively plugged. After the well was opened, the daily liquid production of the well decreased, and the daily oil production increased, with an average daily liquid production of 18.3t and an average daily oil production of 5.7t, and the wellhead temperature was 83.6℃, which indicated that the precise channeling plugging of the high-temperature gas channeling well achieved a remarkable effect of increasing production.

[0052] The above-described embodiments are merely preferred embodiments of the present application, and are not all the embodiments that can be implemented by the present application. Any obvious modifications made by those skilled in the art without departing from the principles and spirit of the present application should be considered to be included in the protection scope of the claims of the present application.

Claims

1. A method for accurate channeling plugging of steam drive high temperature channeling wells, characterized in that, Comprise the following steps: (1) the recent operation of the well, production data, test data analysis, focusing on the study of well temperature test data, the application of "one look, two comparison, three test" analysis method; "one look, two comparison, three test" analysis method is specifically: (1) "one look": the well temperature curve of high temperature steam channeling well is studied, and the well temperature data of high temperature steam channeling layer is obviously higher than that of non steam channeling layer: a) the well temperature of part of the production layer is obviously higher than that of other layers, and the layer is judged to be steam channeling layer; b) the well temperature high point is above the production layer, which indicates that there is a high temperature steam channeling layer above the production layer, which leads to high temperature steam channeling in the upper layer of the well, and the steam channeling layer is the obviously high temperature layer above the well; (2) "two comparison": the well temperature curve of high temperature steam channeling well is compared, and the recent well temperature curve is compared and analyzed, the steam channeling time is determined according to the production characteristics of the well, and the corresponding relationship between the steam channeling time and the well temperature curve change is further determined; a) if the steam channeling time of the well is between two well temperature tests, the analysis and judgment of the steam channeling layer is based on the following well temperature data; b) if there is no well temperature data before and after the steam channeling of the well, the next operation well temperature data is used to analyze and judge the steam channeling layer; (3) "three test": the well temperature test is carried out on the high temperature steam channeling well, the steam channeling layer is preliminarily determined through the analysis and judgment of the above two steps, and the well temperature data is compared and analyzed again to further determine the steam channeling layer; (2) pull out the original well pipe column, explore sand, well cleaning and leakage test; (3) measure well temperature curve and verify steam channeling layer; (4) select steam channeling process according to steam channeling layer; When the steam channeling layer is located in the upper part of the oil layer, the sand filling or ash plug process is designed, the design position is more than 30m from the bottom of the well, the sand filling process is used, and the ash plug process is used when it is less than 30m, the sand surface or ash surface is designed to be 1-2m above the non steam channeling layer, which protects the non steam channeling layer; When the steam channeling layer is located in the lower part of the oil layer, the construction pipe column of drillable cement retainer + thickened oil pipe is lowered, the cement retainer is sealed 1-2m below the non steam channeling layer, the sealing is qualified, the plugging agent is injected, and the upper non steam channeling layer is protected; When the steam channeling layer is located in the middle part of the oil layer, the sand filling or ash plug process is designed, the design position is more than 30m from the bottom of the well, the sand filling process is used, and the ash plug process is used when it is less than 30m, the sand surface or ash surface is designed to be 1-2m above the non steam channeling layer, which protects the lower non steam channeling layer; the construction pipe column of drillable cement retainer + thickened oil pipe is lowered, the cement retainer is sealed 1-2m below the upper non steam channeling layer, the sealing is qualified, the plugging agent is injected, and the upper non steam channeling layer is protected; (5) measure the absorption of steam channeling layer: positive water, displacement 500L / min; Close the casing valve, measure the absorption of steam channeling layer, the highest pressure does not exceed 15MPa; (6) squeeze agent: fill the oil casing annulus with clear water, inject the plugging agent, the displacement is 500L / min, the highest pressure does not exceed 10MPa during the squeezing process, if the pressure exceeds 10MPa, stop the construction immediately; (7) Displacement: Displacement of clean water, displacement capacity 500 L / min, the highest pressure during displacement does not exceed 15 MPa, if the pressure exceeds 15 MPa, immediately stop displacement; pressure diffusion for 10 minutes, oil pipe pressure to 0; reverse circulation washing, wash out the excess plugging agent, washing displacement is not less than 500 L / min, reverse squeeze clean water 1 m 3 , the highest pressure does not exceed 15 MPa, the gray surface position is designed to be higher than the upper boundary of the oil layer by 150 m; (8) drill plug and pressure test: after sealing for 72 hours, explore the ash surface, test the pressure of 15MPa, and the pressure drop is less than 0.5MPa for 30min, which is qualified, continue to drill plug and sand to the artificial well bottom, large displacement reverse washing well until the water in and out is consistent, lower pump and open well.

2. The method for accurate channeling control of steam flooding high temperature channeling well according to claim 1, characterized in that, The blocking agent is composed of inorganic non-metallic cementing agent, microcrystalline reinforcing agent, retarder, thixotropic agent and other additives.

3. The method for accurate channeling control of steam flooding high temperature channeling well according to claim 2, characterized in that, The inorganic non-metallic cementing agent is an industrial slag, and the mass fraction is 72%.

4. The method for accurate channeling of steam drive high temperature channeling well according to claim 2, characterized in that, The microcrystalline reinforcing agent is active alumina powder, and the mass fraction is 8%.

5. The method for accurate channeling of steam drive high temperature channeling well according to claim 2, characterized in that, The retarder is borax / triethanolamine composite retarder, and the mass fraction is 5%.

6. The method for accurate channeling of steam drive high temperature channeling well according to claim 2, characterized in that, The thixotropic agent is calcium bentonite, and the mass fraction is 5%.