Accurate channeling sealing method for steam flooding high-temperature steam channeling well

Abstract

The invention belongs to the field of oil field development and recovery efficiency improvement, and relates to an accurate channeling sealing method for a steam flooding high-temperature steam channeling well, which is used for comprehensively analyzing recent operation, production data and test data of the well, mainly researching well temperature test data and applying an analysis method of'one-view, two-ratio and three-test '. Pulling out an original well pipe column, exploring and washing sand, and drifting to detect leakage; a well temperature curve is measured, and the steam channeling position is verified; selecting a channeling sealing process according to the steam channeling position; measuring the absorption amount of the steam channeling layer; squeezing and injecting the medicament; replacing is conducted; and drilling a plug and testing pressure. After the accurate channeling sealing method for the steam flooding high-temperature steam channeling well is applied to the steam flooding development process of a heavy oil reservoir, the steam channeling position of the high-temperature steam channeling production well is accurately sealed, inter-well steam channeling is effectively inhibited, the displacement effect of the non-steam channeling position is improved, the plugging agent is good in temperature resistance, low in water bleeding rate, high in plugging rate and long in measure validity period, and the method is suitable for large-scale popularization and application. And the steam flooding development effect of the heavy oil reservoir is effectively improved.

Description

Technical Field

[0001] The present invention belongs to the field of oilfield development and recovery enhancement, and relates to a precise sealing method for steam-driven high-temperature steam channeling wells, and specifically to a method suitable for implementing steam drive development in heavy oil reservoirs, and sealing the channeling in production wells corresponding to the steam drive to increase the oil well production. Background Art

[0002] After steam drive development is implemented in heavy oil reservoirs, they generally go through four stages: thermal connectivity, displacement, breakthrough, and erosion adjustment. Affected by factors such as reservoir heterogeneity, few injection stages, and unqualified injection, steam channeling will appear between the injection and production wells, causing the steam injected from the steam injection well to flow along the steam channeling to the production well, resulting in inefficient and ineffective circulation of steam, reducing the steam utilization rate of steam drive and affecting the development effect of steam drive. Some production wells have serious steam channeling, with bottom hole temperatures exceeding 250°C, and production wells showing obvious high temperature, high liquid, and high water content characteristics.

[0003] For high-temperature steam channeling production wells, the production well sealing technology is generally used on site, that is, the plugging agent is squeezed from the production well to seal the steam channeling layer, thereby forcing steam to displace crude oil from the non-steam channeling layer and increase the oil well production. However, in actual applications, on the one hand, due to the non-selectivity of the plugging agent, and on the other hand, the injection process is a general injection into the pipe column, it is impossible to ensure that the agent accurately enters the steam channeling layer. There is a situation where the plugging agent enters the non-steam channeling layer and causes pollution and blockage, affecting the effect of the measures. At the same time, the bottom hole temperature of the high-temperature steam channeling well in the middle and late stages of steam drive development is greater than 250°C, and the plugging agents currently used on site are gel plugging agents or cement plugging agents. The gel plugging agent has a temperature resistance of only 150°C, which cannot meet the technical requirements for sealing high-temperature steam channeling wells, while the cement plugging agent has a temperature resistance of nearly 200°C, and the volume shrinkage rate after curing is 12%. The temperature resistance and water separation rate cannot meet the technical requirements for sealing high-temperature steam channeling wells. Therefore, for steam-driven high-temperature steam channeling wells, there is an urgent need for a precise sealing technology and supporting plugging agents to achieve precise sealing.

[0004] Through literature review and on-site investigation, the current authorized patents only involve methods of profile adjustment or sealing from steam injection wells. There is currently no relevant information or patents on how to perform high-temperature sealing from steam channeling production wells, as well as the corresponding precise sealing technology and methods. Summary of the invention

[0005] In order to solve the problems existing in the prior art, the present invention studies and designs a method for accurately sealing high-temperature steam channeling production wells during steam drive development of heavy oil reservoirs, aiming at the unsatisfactory production conditions of high-temperature steam channeling wells. The method uses technical means to clarify the steam channeling strata, designs injection processes and schemes to achieve precise sealing, designs and develops high-temperature resistant plugging agents, and implements precise sealing of high-temperature steam channeling production wells, thereby improving the production effect of high-temperature steam channeling wells.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A precise sealing method for steam flooding high-temperature steam channeling wells, comprising the following steps:

[0008] (1) Comprehensively analyze the recent operation, production data, and test data of the well, focusing on the well temperature test data, and apply the analysis method of "one look, two comparisons, and three tests";

[0009] (2) Pull out the original well pipe string, perform sand flushing, and conduct well drilling to check for leaks;

[0010] (3) Logging well temperature curve to verify steam channeling layer;

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

[0012] (5) Measure the absorption of the steam channeling layer: pump clean water at a displacement of 500L / min; close the casing valve and measure the absorption of the steam channeling layer. The maximum pressure shall not exceed 15MPa;

[0013] (6) Injection of chemicals: Fill the casing annulus with clean water and inject plugging agent at a rate of 500L / min. The maximum pressure during the injection process shall not exceed 10MPa. If the pressure exceeds 10MPa, stop the construction immediately.

[0014] (7) Displacement: Displace with clean water at a displacement of 500 L / min. The maximum pressure during the displacement process shall not exceed 15 MPa. If the pressure exceeds 15 MPa, the displacement shall be stopped immediately. The pressure shall diffuse for 10 minutes and the oil pipe shall be depressurized to 0. Reverse circulation shall be used to wash out the excess plugging agent. The displacement of the well shall not be less than 500 L / min. The clean water shall be squeezed out for 1 m 3 , the maximum pressure does not exceed 15MPa, and the gray surface position is designed to be 150m above the upper boundary of the oil layer;

[0015] (8) Drilling and pressure testing: After shutting in the well and waiting for 72 hours, probe the ash surface and test the pressure at 15 MPa. If the pressure drop is less than 0.5 MPa in 30 minutes, it is qualified. Continue drilling and flushing sand to the bottom of the artificial well. Backwash the well with a large displacement until the inlet and outlet water are consistent, and then lower the pump to open the well.

[0016] Furthermore, the analysis method of "one look, two comparisons, three tests" is specifically as follows:

[0017] (1) “At first glance”: The temperature curve of the high-temperature steam channeling well was studied. The temperature data of the high-temperature steam channeling layer was significantly higher than that of the non-steam channeling layer:

[0018] a) The well temperature of some production layers is significantly higher than that of other layers, and it is judged that the layer is a steam channeling layer;

[0019] b) The high point of well temperature is located above the production layer, indicating that there is a high-temperature steam channeling layer above the production layer, which leads to high temperature of the upper layer of the well due to steam channeling. The steam channeling layer is an obviously high-temperature layer in the upper part of the well;

[0020] (2) “Two comparisons”: Compare the well temperature curves of high-temperature steam channeling wells with those of recent well temperature curves, determine the steam channeling time based on the production characteristics of the wells, and further determine the corresponding relationship between the steam channeling time and the change in the well temperature curve;

[0021] a) If the steam channeling time of the well is between two well temperature tests, the analysis and judgment of the steam channeling layer shall be based on the later well temperature data;

[0022] b) If there is no well temperature data before and after the steam breakthrough, the steam breakthrough layer shall be determined by analyzing the well temperature data of the next operation;

[0023] (3) “Three tests”: Conduct well temperature tests on high-temperature steam channeling wells. Through the analysis and judgment of the above two steps, the steam channeling layer has been preliminarily determined. Comparative analysis of the well temperature data can further determine the steam channeling layer.

[0024] Furthermore, when the steam channeling layer in the sealing process is located on the upper part of the oil layer, a sand filling or ash plugging process is designed. The sand filling process is used when the design position is greater than 30m from the bottom of the well, and the ash plugging process is used when the design position is less than 30m. The sand surface or ash surface is designed to be 1-2m above the non-steam channeling layer to protect the non-steam channeling layer.

[0025] Furthermore, when the steam channeling layer is located at the lower part of the oil layer in the sealing process, a construction pipe string of a drillable cement retainer + thickened oil pipe is lowered, and the cement retainer is sealed 1-2m below the non-steam channeling layer. After the sealing is qualified, a plugging agent is injected to protect the upper non-steam channeling layer.

[0026] Furthermore, when the steam channeling layer is located in the middle of the oil layer in the sealing process, a sand filling or ash plugging process is designed. If the design position is greater than 30m from the bottom of the well, the sand filling process is used, and if it is less than 30m, the ash plugging process is used. The sand surface or ash surface is designed to be 1-2m above the non-steam channeling layer to protect the lower non-steam channeling layer; a construction string of a drillable cement retainer + thickened oil pipe is lowered, and the cement retainer is sealed 1-2m below the upper non-steam channeling layer. After the sealing is qualified, a plugging agent is injected to protect the upper non-steam channeling layer.

[0027] Furthermore, the plugging agent is composed of an inorganic non-metallic gelling agent, a microcrystalline reinforcing agent, a retarder, a thixotropic agent and other additives.

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

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

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

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

[0032] Furthermore, the ratio of the other auxiliary agents is 10%.

[0033] Technical indicators of high temperature resistant inorganic sealing agent

[0034] Breakthrough pressure 1.53MPa / cm Water separation rate ≤0.8％ Temperature resistance 350℃ Blockage rate ≥99％ Thickening time 4-10h adjustable

[0035] The development of the above-mentioned high temperature resistant inorganic channeling agent is divided into the following aspects:

[0036] (1) Design the sealing radius. If the steam channeling coefficient (maximum temperature of the steam channeling layer / average temperature of the oil layer) is less than 1.5, the sealing radius is 1.5-2m; if the steam channeling coefficient is ≥1.5, the sealing radius is 2-2.5m.

[0037] (2) Design the curing time. Combined with the construction schedule, ensure that the curing time is reduced while ensuring construction safety, thereby improving the sealing strength and ensuring the sealing effect. The curing time is determined to be 4-6 hours.

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

[0039] The beneficial effects of the present invention compared with the prior art are:

[0040] After the precise sealing method of steam-driven high-temperature steam channeling wells was applied in the steam-driven development process of heavy oil reservoirs, the steam channeling layers of high-temperature steam channeling production wells were precisely sealed, the steam channeling between wells was effectively suppressed, and the displacement effect of non-steam channeling layers was improved. The plugging agent has good temperature resistance, low water separation rate, high sealing rate, and a long effective period of the measure, which effectively improves the steam-driven development effect of heavy oil reservoirs. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical scheme and advantages of the present invention clearer, the following is a further detailed description of the implementation methods of the present invention. Unless otherwise specified, the experimental methods used in the present invention are conventional methods, and the experimental equipment, materials, reagents, etc. used can be obtained from commercial channels.

[0042] The present invention has been widely used in high-temperature steam channeling production wells in steam flooding development of a heavy oil reservoir, and has achieved good implementation effects, which are specifically achieved as follows:

[0043] Example 1

[0044] The production well has been converted to steam drive production since 2011. The production layer is 893.0-931.7m, with a total of 8 oil layers and a thickness of 15.4m. Steam channeling began in August 2019, with an average daily liquid production of 27.8m 3 , with a daily oil production of 1.2 tons, a wellhead temperature of 95°C, and well temperature data showing that the highest formation temperature was 218.5°C. In the early stage, a general plugging technology was implemented, using gel plugging agents, but the measures were not effective. In order to improve the production level of the well, the well was precisely plugged with steam drive high-temperature steam channeling wells.

[0045] Apply this method as follows:

[0046] Step 1: Comprehensively analyze the recent operation, production data, and test data of the well, focusing on the well temperature test data, and apply the analysis method of "one look, two comparisons, and three tests". Comparing the well temperature data before and after steam channeling, the highest well temperature point of 218.5℃ appeared at 897.0m after steam channeling, and it was only 176.2℃ before steam channeling. It was analyzed that steam channeling occurred in this layer, and the specific layer was 893.0-900.6m, a total of 4.8m.

[0047] Step 2: Well repair, pipe lifting, sand flushing, well leak detection, well temperature curve logging. Data shows that the highest point of the formation temperature is still at 897.0m, and the highest temperature is 225.2℃. Based on the above data, the steam channeling layer is determined to be 893.0-900.6m, a total of 4.8m. The average temperature of the oil layer is 162.4℃, the steam channeling coefficient is 1.4, the sealing radius is designed to be 1.8m, and the amount of reagents is 23m 3 , the curing time is 4 hours, and the specific gravity of the plugging agent solution is 1.8.

[0048] Step 3: Squeeze clean water to test the steam channeling absorption. The squeezing pressure is 3MPa and the result is 50m 3 / h, meeting the construction requirements. Clean water is squeezed to fill the casing annulus, and plugging agent is injected 23m 3 , construction pressure 8.6MPa. Positive squeeze water 2.5m 3 , according to the pressure change, intermittently squeeze out clean water 5.1m 3 , until the pressure rises to 15MPa, shut in the well and wait for 72 hours.

[0049] Step 4: Exploring the ash surface, the ash surface position is 752.5m, the test pressure is 15MPa, the pressure drop in 30min is less than 0.5MPa, the construction is qualified. Continue drilling and flushing sand to the bottom of the artificial well, backwash the well until the inlet and outlet water are consistent, and then lower the pump to open the well.

[0050] Implementation effect:

[0051] After the implementation, the formation temperature of the original steam channeling layer of the production well dropped to 159.2℃, and the temperature of the non-steam channeling layer was 182.9℃, indicating that the original steam channeling layer was effectively blocked. After the well was opened, the daily liquid production of the well decreased compared with that before the measures, and the daily oil production increased, with an average daily liquid and oil production of 18.3 / 5.7t, and the wellhead temperature was 83.6℃, ​​indicating that the precise blocking of the high-temperature steam channeling well in the well achieved a significant increase in production.

[0052] The above-described embodiments are only preferred embodiments of the present invention, but not all feasible embodiments of the present invention. For those skilled in the art, any obvious changes made thereto without departing from the principles and spirit of the present invention should be considered to be included in the scope of protection of the claims of the present invention.

Claims

1. A precise sealing method for steam flooding high-temperature steam channeling wells, characterized in that: The following steps are involved: (1) Comprehensively analyze the recent operation, production data, and test data of the well, focusing on the well temperature test data, and apply the "one look, two comparisons, three tests" analysis method; (2) Pull out the original well pipe string, perform sand flushing, and conduct well drilling to check for leaks; (3) Logging well temperature curve to verify steam channeling layer; (4) Select sealing technology according to the steam channeling layer; (5) Measure the absorption of the steam channeling layer: pump clean water at a displacement of 500L / min; close the casing valve and measure the absorption of the steam channeling layer. The maximum pressure shall not exceed 15MPa; (6) Injection of chemicals: Fill the casing annulus with clean water and inject plugging agent at a rate of 500L / min. The maximum pressure during the injection process shall not exceed 10MPa. If the pressure exceeds 10MPa, stop the construction immediately. (7) Displacement: Displace with clean water at a displacement of 500 L / min. The maximum pressure during the displacement process shall not exceed 15 MPa. If the pressure exceeds 15 MPa, the displacement shall be stopped immediately. The pressure shall diffuse for 10 minutes and the oil pipe shall be depressurized to 0. Reverse circulation shall be used to wash out the excess plugging agent. The displacement of the well shall not be less than 500 L / min. The clean water shall be squeezed out for 1 m 3 , the maximum pressure does not exceed 15MPa, and the gray surface position is designed to be 150m above the upper boundary of the oil layer; (8) Drilling and pressure testing: After shutting in the well and waiting for 72 hours, probe the ash surface and test the pressure at 15 MPa. If the pressure drop is less than 0.5 MPa in 30 minutes, it is qualified. Continue drilling and flushing sand to the bottom of the artificial well. Backwash the well with a large displacement until the inlet and outlet water are consistent, and then lower the pump to open the well.

2. The precise sealing method for high-temperature steam channeling wells in steam drive according to claim 1 is characterized in that: The analysis method of "one look, two comparisons, three tests" is specifically: (1) "At a glance": The temperature curve of the high-temperature steam channeling well was studied. The temperature data of the high-temperature steam channeling layer was significantly higher than that of the non-steam channeling layer: a) The well temperature of some production layers is significantly higher than that of other layers, and it is judged that the layer is a steam channeling layer; b) The high point of well temperature is located above the production layer, indicating that there is a high-temperature steam channeling layer above the production layer, which leads to high temperature of the upper layer of the well due to steam channeling. The steam channeling layer is an obviously high-temperature layer in the upper part of the well; (2) "Two comparisons": compare the well temperature curves of high-temperature steam channeling wells with those of recent well temperature curves, determine the steam channeling time based on the production characteristics of the wells, and further determine the corresponding relationship between the steam channeling time and the change in the well temperature curve; a) If the steam channeling time of the well is between two well temperature tests, the analysis and judgment of the steam channeling layer shall be based on the later well temperature data; b) If there is no well temperature data before and after the steam breakthrough, the steam breakthrough layer shall be determined by analyzing the well temperature data of the next operation; (3) "Three tests": well temperature tests are conducted on high-temperature steam channeling wells. Through the analysis and judgment of the above two steps, the steam channeling layer has been preliminarily determined. Comparative analysis of the well temperature data is then conducted to further determine the steam channeling layer.

3. The precise sealing method for steam flooding high-temperature steam channeling wells according to claim 1 is characterized in that: When the steam channeling layer in the sealing process is located at the upper part of the oil layer, a sand filling or ash plugging process is designed. The sand filling process is used when the design position is greater than 30m from the bottom of the well, and the ash plugging process is used when the design position is less than 30m. The sand surface or ash surface is designed to be 1-2m above the non-steam channeling layer to protect the non-steam channeling layer.

4. The precise sealing method for steam flooding high-temperature steam channeling wells according to claim 1 is characterized in that: When the steam channeling layer is located at the lower part of the oil layer in the sealing process, a construction pipe string of a drillable cement retainer + thickened oil pipe is lowered, and the cement retainer is sealed 1-2m below the non-steam channeling layer. After the sealing is qualified, a plugging agent is injected to protect the upper non-steam channeling layer.

5. The precise sealing method for steam flooding high-temperature steam channeling wells according to claim 1 is characterized in that: When the steam channeling layer is located in the middle of the oil layer in the sealing process, a sand filling or ash plugging process is designed. The sand filling process is used when the design position is greater than 30m from the bottom of the well, and the ash plugging process is used when the design position is less than 30m. The sand surface or ash surface is designed to be 1-2m above the non-steam channeling layer to protect the lower non-steam channeling layer; a construction string of a drillable cement retainer + thickened oil pipe is lowered, and the cement retainer is sealed 1-2m below the upper non-steam channeling layer. After the sealing is qualified, a plugging agent is injected to protect the upper non-steam channeling layer.

6. The precise sealing method for high-temperature steam channeling wells in steam drive according to claim 1 is characterized in that: The plugging agent is composed of an inorganic non-metallic gelling agent, a microcrystalline reinforcing agent, a retarder, a thixotropic agent and other auxiliary agents.

7. The precise sealing method for steam flooding high-temperature steam channeling wells according to claim 6 is characterized in that: The inorganic non-metallic gelling agent is an industrial slag with a mass fraction of 72%.

8. The precise sealing method for high-temperature steam channeling wells in steam drive according to claim 6 is characterized in that: The microcrystalline reinforcing agent is active alumina micropowder, and the mass fraction thereof is 8%.

9. The precise sealing method for high-temperature steam channeling wells in steam drive according to claim 6, characterized in that: The retarder is a borax / triethanolamine composite retarder with a mass fraction of 5%.

10. The precise sealing method for steam flooding high-temperature steam channeling wells according to claim 6, characterized in that: The thixotropic agent is calcium bentonite, and the mass fraction thereof is 5%.