Device and method for oil well sand control using nitrogen foam
By using nitrogen foam sand carrying liquid technology, problems such as complex construction and poor sand protection in oil wells are solved, and efficient sand protection effect is achieved, which significantly improves sand carrying capacity and production cycle.
Patent Information
- Application Number
- CN202210630235.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-06-06
- Publication Date
- 2025-02-14
- Estimated Expiration
- 2042-06-06
AI Technical Summary
The existing oil well sand prevention technology has problems such as complex construction, high cost, poor sand prevention effect, large amount of sand carrying liquid, uneven sand laying of proppants on multi-layer non-homogeneous wells, easy blockage of small holes, and weak sand prevention barriers.
Nitrogen bubble sand-carrying liquid is used to combine equipment such as liquid nitrogen pump truck, sand mixing truck, sand-carrying liquid pump truck, three-phase foam generator to form nitrogen foam sand-carrying liquid, and inject oil wells through sliding wellheads and casings to form sand walls To improve sand protection effect.
It significantly improves the sand carrying capacity and sand prevention effect of foam sand carrying liquid, reduces filtration loss and liquid usage, increases the thickness and length of the sand wall, extends the production cycle, and reduces the sand removal and sand blocking of the leakage wells.
Smart Images
Figure CN114991721B_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the field of oil and gas resource development, and in particular, relates to a device and method for oil well sand prevention using nitrogen foam. Background Art
[0002] my country's loose sandstone reservoirs are widely distributed and occupy an important position in oil production. Sand production from oil wells is one of the main contradictions in the exploitation of such reservoirs. With the development of my country's oil industry, oil well sand control technology has been continuously improved and matured. However, when oil well development enters the middle and late stages, the formation energy often decreases, the number of leaking wells increases, and the sand control effect gradually deteriorates. The amount of sand-carrying fluid used in most sand control wells has gradually increased, especially in multi-layer heterogeneous wells. After multiple sand control, the proppant is easy to penetrate along the large pores, and the small pores cannot be effectively improved and are easily blocked, resulting in a weak sand control barrier.
[0003] In order to achieve the sand control effect, the existing sand control methods include mechanical sand control and chemical sand control. The first type of mechanical sand control uses gravel filling to prevent sand, the second type of mechanical sand control uses sand control pipes for sand control, and chemical sand control uses chemicals to increase the cohesion of sand to form a better adhesive for sand control; the above sand control methods have the following shortcomings:
[0004] (1) The construction of the first type of mechanical sand control is complex and requires high one-time investment. If the gravel size is not selected properly, the formation sand will invade the gravel layer, which will increase the resistance of oil flowing into the well and affect the oil well production capacity after sand control.
[0005] (2) The sand control pipe column of the second type of mechanical sand control is easily blocked by formation sand. It can only prevent formation sand from being produced to the ground but cannot prevent formation sand from entering the wellbore. It has a short effective period and is only suitable for medium and coarse sandstone formations with an oil sand median value greater than 0.1 mm.
[0006] (3) The strength of chemical sand control is low and cannot meet the needs of large-scale production. It has a certain impact on the permeability of the formation. It is suitable for sand control in thin layers with relatively uniform permeability. However, chemical sand control construction in thick layers with large differences within the layer is prone to uneven consolidation due to uneven cone penetration of the injection agent and gravity, which affects the sand control effect. The injection agent of chemical sand control has aging phenomenon and the effective period of sand control is short. It is not suitable for sand control in open hole wells.
[0007] Based on the above reasons, there is an urgent need for an effective oil well sand control device and method to improve the sand carrying capacity of the sand-carrying fluid, reduce the filtration loss of the sand-carrying fluid, prevent sand shedding and sand plugging in the leakage well, thereby efficiently solving the oil well leakage problem, significantly improving the sand control effect, reducing the amount of sand-carrying fluid used in sand control wells, achieving the effect of uniform sand spreading, and at the same time increasing the liquid production and extending the production cycle. Summary of the invention
[0008] In order to solve the defects and shortcomings of the existing methods in oil well sand control, and overcome the problems of serious oil well leakage, poor sand control effect, large amount of sand-carrying fluid, uneven sand spreading of multi-layer heterogeneous well proppants, easy blockage of small pores, and weak sand control barrier, the present invention provides a device and method for oil well sand control using nitrogen foam.
[0009] To achieve the above object, the present invention adopts the following technical solution:
[0010] The device for oil well sand prevention using nitrogen foam includes: liquid nitrogen pump truck, sand mixing truck, sand-carrying liquid pump truck, three-phase foam generator, sliding wellhead, casing, oil pipe, packer, filling tool, screen, perforation, wire plug, sand wall and artificial well bottom; the characteristics are: 2 units with a pressure of 45MPa and a pumping rate of 2500Nm 3 The bottom of the liquid nitrogen pump truck with a capacity of / h is connected in parallel through a pipeline to the gas phase inlet of the three-phase foam generator with a pressure of 70MPa, so as to pump nitrogen into the three-phase foam generator; the bottom of the sand mixing truck is connected to the top of the sand carrying liquid pump truck through a pipeline, so as to inject sand into the sand carrying liquid pump truck; the sand carrying liquid pump truck is connected to the liquid phase inlet of the three-phase foam generator through a pipeline, so as to input the foam sand carrying liquid into the three-phase foam generator; the outlet of the three-phase foam generator is connected to the sliding wellhead of the oil well through a pipeline, so as to mix nitrogen, sand carrying liquid and sand to make nitrogen foam sand carrying liquid, and inject it into the sliding wellhead; the bottom of the sliding wellhead is connected to the top of the casing and the oil pipe; the casing passes through the overlying strata and sandstone reservoir from top to bottom in sequence. The casing is connected to the upper part of the underlying stratum, and there is an artificial well bottom at the bottom of the casing; perforations are arranged on the casing in the sandstone reservoir, which can provide a channel for the nitrogen foam sand-carrying fluid to enter the sandstone reservoir to form a sand wall, and there are concentric oil pipes inside the casing; the bottom of the oil pipe is connected to the filling tool, and a packer is installed at the position between the top of the sandstone reservoir and the casing of the oil pipe to prevent the nitrogen foam sand-carrying fluid from overflowing to the upper part of the casing; a filling tool is installed below the packer to inject the nitrogen foam sand-carrying fluid between the oil pipe and the casing, and the nitrogen foam sand-carrying fluid is then input into the sandstone reservoir through the perforations; a screen is installed below the filling tool to prevent sand from entering the oil pipe, and there is a channel for liquid to return to the oil pipe at the connection between the screen and the oil pipe, and there is a wire plug at the bottom of the screen.
[0011] The method for oil well sand control using nitrogen foam, using the above-mentioned device for oil well sand control using nitrogen foam, comprises the following steps:
[0012] S1. Preparation before construction;
[0013] S2, nitrogen foam preparation;
[0014] S3, wellhead pressure measurement;
[0015] S4, pre-foam liquid injection and step-by-step sand addition;
[0016] S5, displacement fluid injection;
[0017] S6, let go of pressure, shut down the well to release pressure and release the blowout;
[0018] S7, backwash well;
[0019] S8. Re-explore the sand surface of the center pipe and pull out the pipe string.
[0020] Compared with the prior art, the present invention has the following beneficial effects: it is suitable for oil wells with sand production, serious formation leakage, and large differences in permeability of different formations caused by the mining area spanning multiple formations; compared with conventional sand control, the sand carrying capacity of the foam sand-carrying liquid is effectively improved, and under the same amount of sand-carrying liquid, the amount of sand added is increased by 20%, and the sand carrying capacity is increased by more than 3 times; the filtration loss of the foam sand-carrying liquid is effectively reduced, and the filtration loss is reduced by more than 60%; it is easier to reach the designed sand addition amount, and the liquid consumption is reduced by 20-30% under the same amount of sand addition; the thickness of the sand wall is increased by 1 time, the length is increased by 1 time, the seepage area is increased by 2-3 times, and the dynamic liquid level height is increased by 20%; the phenomenon of sand shedding and sand plugging during the construction of foam sand control in leakage wells is reduced, and the viscosity of the conventional sand-carrying liquid can be increased by more than 3 times; for sand control of heterogeneous old wells, the effect of uniform sand spreading can be achieved; the liquid production is increased by 2 times, and the production cycle is extended by 50%. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] Figure 1 It is a schematic diagram of a device for preventing sand from entering an oil well by using nitrogen foam;
[0022] In the figure: 1. nitrogen pump truck; 2. sand mixing truck; 3. sand-carrying liquid pump truck; 4. three-phase foam generator; 5. sliding wellhead; 6. overlying stratum; 7. casing; 8. oil pipe; 9. packer; 10. filling tool; 11. screen; 12. perforation; 13. wire plug; 14. sand wall; 15. sandstone reservoir; 16. artificial well bottom; 17. underlying stratum. DETAILED DESCRIPTION
[0023] like Figure 1 As shown, the device for preventing sand in oil wells by using nitrogen foam includes: a liquid nitrogen pump truck 1, a sand mixing truck 2, a sand-carrying liquid pump truck 3, a three-phase foam generator 4, a sliding wellhead 5, a casing 7, an oil pipe 8, a packer 9, a filling tool 10, a screen 11, a perforation 12, a wire plug 13, a sand wall 14 and an artificial well bottom 16; among them: two of them have a pressure bearing capacity of 45MPa and a pumping rate of 2500Nm 3The bottom of the liquid nitrogen pump truck 1 with a capacity of 10000 tons / h is connected in parallel through a pipeline to the gas phase inlet of the three-phase foam generator 4 with a pressure of 70 MPa, so as to pump nitrogen into the three-phase foam generator 4; the sand mixing truck 2 is connected to the sand carrying liquid pump truck 3 through a pipeline, and the sand mixing truck 2 injects sand into the sand carrying liquid pump truck 3; the sand carrying liquid pump truck 3 is connected to the liquid phase inlet of the three-phase foam generator 4 through a pipeline, so as to input the foam sand carrying liquid into the three-phase foam generator 4; the three-phase foam generator 4 is used to mix nitrogen, sand carrying liquid and sand to form nitrogen foam sand carrying liquid, and the outlet of the three-phase foam generator 4 is connected to the sliding wellhead 5 of the oil well through a pipeline, and the nitrogen foam sand carrying liquid is injected into the sliding wellhead 5; the bottom of the sliding wellhead 5 is connected to the top of the casing 7 and the oil pipe 8; the casing 7 passes through the overlying stratum 6 and the sandstone reservoir 15 from top to bottom in sequence until the upper part of the underlying stratum 17, The bottom of the casing 7 is connected to the top of the artificial well bottom 16; the casing 7 in the sandstone reservoir 15 is provided with perforations 12, which can provide a channel for the nitrogen foam sand-carrying liquid to enter the sandstone reservoir 15 to form a sand wall 14, and a concentric oil pipe 8 is arranged inside the casing 7; the bottom of the oil pipe 8 is connected to the top of the packing tool 10, and the oil pipe 8 is installed with a packer 9 at a position between the top of the sandstone reservoir 15 and the casing 7, which is used to prevent the nitrogen foam sand-carrying liquid from overflowing to the upper part of the casing 7; the packing tool 10 is installed below the packer 9, which is used to inject the nitrogen foam sand-carrying liquid between the oil pipe 8 and the casing 7, and the nitrogen foam sand-carrying liquid is then input into the sandstone reservoir 15 through the perforations 12; the screen tube 11 is installed below the packing tool 10, which is used to prevent sand from entering the oil pipe 8, and there is a channel for liquid to return to the oil pipe at the connection between the screen tube 11 and the oil pipe 8, and there is a wire plug 13 at the bottom of the screen tube 11.
[0024] The above-mentioned device and method for oil well sand control using nitrogen foam include the following steps:
[0025] S1. Preparation before construction
[0026] The original production tubing in the well was pulled out at a rate of 40-50 pipes / hour, and the scaling and corrosion of the tools were observed and described, and recorded; the original wellhead was replaced with a sliding wellhead, and the pressure test was required to be qualified; the oil pipe was lowered, and the sand surface was adjusted by sand flushing; the casing was scraped to the well depth, and scraped at the packer setting position; the sand control tubing was measured and equipped according to the tubing design on site. The sand control tubing was a combination of tubing, filling tools, screens and wire plugs, and was smoothly lowered into the well so that the sand control tubing faced the oil layer; the hanging weight and leakage of the tubing were recorded; the tubing was lifted 35cm, and water was poured into the tubing. After it was filled, the tubing was pressurized in stages to 4MPa, 6MPa, and 8M Pa, 10MPa, 12MPa, 14MPa, each maintain pressure for 3 minutes; press down and lift the pipe column to test the sealing. After passing the test, continue to increase the pressure to 18MPa, the pressure suddenly drops to 0, and the filling channel is opened. After the filling channel is opened, the well is washed to the outlet and the liquid returns normally, and the well washing pressure is normal; connect 2 nitrogen pump trucks in parallel to the gas phase inlet of the three-phase foam generator through pipelines, connect the sand mixing truck to the sand carrying liquid pump truck through pipelines, and connect the sand carrying liquid pump truck to the liquid phase inlet of the three-phase foam generator through pipelines, and connect the three-phase foam generator outlet to the sliding wellhead; a single liquid nitrogen pump truck has a pressure bearing capacity of 45MPa and a pumping rate of 2500Nm 3 / h, the three-phase foam generator can withstand a pressure of 70MPa; connect the sand control and backwash well construction pipelines; conduct a pressure test on the ground pipeline, the test pressure is 33MPa, and it is considered qualified if there is no puncture or leakage within 5 minutes.
[0027] S2. Nitrogen foam preparation
[0028] 99.999% liquid nitrogen is injected into two parallel liquid nitrogen pump trucks respectively; guar gum, 0.01% by volume of bactericide, 1% by volume of anti-swelling agent, 0.5% by volume of drainage agent and 1% by volume of foaming agent are added to clean water to prepare foaming sand-carrying liquid; the sand particle size gradation in the sand mixing truck is 20-40 mesh (sieve mesh size 0.85mm-0.425mm), and the compressive strength meets the design requirements; the sand is mixed with the foaming sand-carrying liquid to prepare foam sand-carrying liquid, and the foam sand-carrying liquid and nitrogen are added into the foam generator at the same time and fully mixed to generate nitrogen foam sand-carrying liquid, which is injected into the sliding wellhead after inspection.
[0029] S3, wellhead pressure measurement
[0030] Monitor the wellhead injection pressure on site and adjust the nitrogen foam sand-carrying fluid injection rate according to the wellhead injection pressure. When the wellhead injection pressure is 0-10MPa, the injection rate is 3m 3 / min; when the wellhead injection pressure is 10-20MPa, the injection rate is 2.5m 3 / min, when the wellhead injection pressure is 20-33MPa, the injection rate is 2m 3 / min; the construction pressure limit of nitrogen foam sand-carrying liquid injection is 33MPa.
[0031] S4, pre-foam injection and step-by-step sanding
[0032] Inject 50-80m of pre-foam liquid into the well 3 , the pre-foam liquid component is the formation water of this block with a volume percentage of 1% foaming agent, the pressure fluctuation does not exceed 2MPa, the pressure is stable for 5min, and sand addition begins; the foam sand-carrying liquid with a volume ratio of sand to foam sand-carrying liquid of 10% is injected, and after the wellhead pressure is stable for 2min, the foam sand-carrying liquid with a volume ratio of sand to foam sand-carrying liquid of 20% is injected, and after the wellhead pressure is stable for 2min, the next level of sand addition is started, and each level of sand addition concentration increases by 10% compared with the previous level, until the volume ratio of sand to foam sand-carrying liquid is 70%, and it is stable for 2min; if the pressure rises by more than 2MPa within 2min, stop adding sand, and inject 10m of foam sand-carrying liquid without sand 3 , observe the changes in pumping pressure. If the pressure tends to be stable, continue to add sand according to the construction design until the construction is completed and the design requirements are met; if the pressure continues to rise, stop construction.
[0033] S5. Displacement fluid injection
[0034] After the sand is added, the foaming sand-carrying liquid without sand and nitrogen is injected according to the designed displacement amount. The displacement amount formula is:
[0035] V 顶替 =(V 地面 +V 油管 )×90%
[0036] Among them, V 顶替 is the displacement fluid volume, V 地面 is the surface pipeline volume, V 油管 is the tubing volume; the injection rate is 0.5m 3 / min, the injection pressure shall not exceed 10MPa; on-site technicians need to adjust the construction displacement according to the wellhead pressure.
[0037] S6, let go of pressure, shut down the well to release pressure and release the blowout
[0038] Lift the tubing to the original hanging weight, rotate the tubing column 30 times forward to achieve tubing release, and lift the tubing to 1m above the wellhead; close the tubing and casing valves for 24 hours. If the tubing and casing wellhead pressure is not 0, install an oil nozzle at the tubing outlet and select the corresponding oil nozzle diameter in Table 1 according to the tubing wellhead pressure, and spray until the wellhead pressure is 0.
[0039] Table 1 Correspondence between tubing wellhead pressure and nozzle diameter
[0040] Tubing wellhead pressure >5.0MPa 3.0-5.0MPa 1.0-3.0MPa <1.0MPa Nozzle diameter 3mm 5mm 8mm Open
[0041] S7, backwash well
[0042] Use the formation water in this area to backwash the well, with the formation water injection rate of 300-600L / min, until the returned fluid has the same fluidity as the injected formation water; after the well washing is completed, pull out the discarding string.
[0043] S8. Re-exploring the sand surface of the central pipe and pulling out the pipe string
[0044] A sand flushing string containing at least 80m of Φ42mm flushing pipe and oil pipe is lowered to re-explore the sand surface of the central pipe. If there is sand, backwash the sand until the thread plug is found. The formation water of the area is used for sand flushing, and the injection rate is 300-600L / min, until the returned fluid is consistent with the injected formation water. The sand flushing string in the well is pulled out and the construction is completed.
[0045] Thus, the present invention can effectively improve the sand carrying capacity of the foam sand-carrying liquid, reduce the filtration loss of the foam sand-carrying liquid, reduce the amount of liquid used, increase the thickness and length of the sand wall, reduce the sand shedding and sand plugging phenomena during the foam sand prevention construction process of the lost well, significantly improve the viscosity of the sand-carrying liquid, achieve the effect of uniform sand spreading, significantly increase the liquid production, and extend the production cycle.
Claims
1. A method for oil well sand control using nitrogen foam, and a device for oil well sand control using nitrogen foam, comprising: Liquid nitrogen pump truck, sand mixer truck, sand-carrying liquid pump truck, three-phase foam generator, sliding wellhead, casing, tubing, packer, filling tool, screen, perforation, wire plug, sand wall and artificial well bottom; among them, 2 units have a pressure of 45MPa and a pumping rate of 2500Nm 3 The bottom of the liquid nitrogen pump truck with a capacity of / h is connected in parallel through a pipeline to the gas phase inlet of the three-phase foam generator with a pressure of 70MPa, so as to pump nitrogen into the three-phase foam generator; the bottom of the sand mixing truck is connected to the top of the sand carrying liquid pump truck through a pipeline, so as to inject sand into the sand carrying liquid pump truck; the sand carrying liquid pump truck is connected to the liquid phase inlet of the three-phase foam generator through a pipeline, so as to input the foam sand carrying liquid into the three-phase foam generator; the outlet of the three-phase foam generator is connected to the sliding wellhead of the oil well through a pipeline, so as to mix nitrogen, sand carrying liquid and sand to make nitrogen foam sand carrying liquid, and inject it into the sliding wellhead; the bottom of the sliding wellhead is connected to the top of the casing and the oil pipe; the casing passes through the overlying strata and the sandstone reservoir from top to bottom in sequence until it reaches the upper surface of the underlying strata The casing has an artificial bottom; the casing in the sandstone reservoir is provided with perforations, which can provide a channel for the nitrogen foam sand-carrying liquid to enter the sandstone reservoir to form a sand wall, and there is a concentric oil pipe inside the casing; the bottom of the oil pipe is connected to the filling tool, and a packer is installed at the position between the top of the sandstone reservoir and the casing of the oil pipe to prevent the nitrogen foam sand-carrying liquid from overflowing to the upper part of the casing; a filling tool is installed below the packer to inject the nitrogen foam sand-carrying liquid between the oil pipe and the casing, and the nitrogen foam sand-carrying liquid is then input into the sandstone reservoir through the perforations; a screen is installed below the filling tool to prevent sand from entering the oil pipe, and there is a channel for liquid to return to the oil pipe at the connection between the screen and the oil pipe, and there is a wire plug at the bottom of the screen; it is characterized in that it includes the following steps: S1. Preparation before construction; S2, nitrogen foam preparation; S3, wellhead pressure measurement; S4, pre-foam liquid injection and step-by-step sand addition; S5, displacement fluid injection; S6, let go of pressure, shut down the well to release pressure and release the blowout; S7, backwash well; S8. Re-explore the sand surface of the center pipe and pull out the pipe string; The steps of S1 are as follows: pull out the original production tubing in the well at a rate of 40-50 tubes / hour, observe and describe the scaling and corrosion of the tools, and record them; replace the original wellhead with a sliding wellhead, and require the pressure test to be qualified; lower the oil pipe, and adjust the sand surface by sand flushing; scrape the casing to the well depth, and scrape it at the packer setting position; measure and equip the sand control tubing according to the tubing design on site. The sand control tubing is a combination of tubing, filling tools, screens and wire plugs, and is lowered steadily into the well so that the sand control tubing faces the oil layer; record the hanging weight and leakage of the tubing; lift the tubing 35cm, fill the tubing with water, and after it is filled, pressurize the tubing in stages to 4MPa and 6MPa , 8MPa, 10MPa, 12MPa, 14MPa, each maintaining pressure for 3 minutes; press down and lift the pipe column to test the sealing. After passing the test, continue to increase the pressure to 18MPa, the pressure suddenly drops to 0, and the filling channel is opened. After the filling channel is opened, the well is washed to the outlet with normal return liquid and normal well washing pressure; connect 2 nitrogen pump trucks in parallel to the gas phase inlet of the three-phase foam generator through pipelines, connect the sand mixing truck to the sand carrying liquid pump truck through pipelines, and connect the sand carrying liquid pump truck to the liquid phase inlet of the three-phase foam generator through pipelines, and connect the three-phase foam generator outlet to the sliding wellhead; a single liquid nitrogen pump truck has a pressure resistance of 45MPa and a pumping rate of 2500Nm 3 / h, the three-phase foam generator can withstand a pressure of 70MPa; connect the sand control and backwash well construction pipelines; test the surface pipelines at a pressure of 33MPa, and if there is no puncture or leakage within 5 minutes, it is considered qualified; Step S2 is as follows: inject 99.999% liquid nitrogen into two parallel liquid nitrogen pump trucks respectively; add guar gum, 0.01% by volume of fungicide, 1% by volume of anti-swelling agent, 0.5% by volume of drainage agent and 1% by volume of foaming agent into clean water to prepare foaming sand-carrying liquid; the sand particle size gradation in the sand mixing truck is 20-40 mesh, and the compressive strength meets the design requirements; mix the sand with the foaming sand-carrying liquid to prepare foam sand-carrying liquid, add the foam sand-carrying liquid and nitrogen into the foam generator at the same time and mix them fully to generate nitrogen foam sand-carrying liquid, and inject it into the sliding wellhead after inspection; The S3 step is as follows: monitor the on-site wellhead injection pressure, adjust the nitrogen foam sand-carrying fluid injection rate according to the wellhead injection pressure, and the injection rate is 3m when the wellhead injection pressure is 0-10MPa. 3 / min; when the wellhead injection pressure is 10-20MPa, the injection rate is 2.5m 3 / min, when the wellhead injection pressure is 20-33MPa, the injection rate is 2m 3 / min; The construction pressure limit of nitrogen foam sand-carrying liquid injection is 33Mpa; The steps of S4 are as follows: Inject 50-80m3 of pre-foam fluid into the well. 3 The pre-foam liquid component is the formation water of this block with a volume percentage of 1% foaming agent. The pressure fluctuation does not exceed 2MPa. After the pressure is stable for 5 minutes, sand addition begins. The foam sand-carrying liquid with a volume ratio of sand to foam sand-carrying liquid of 10% is injected. After the wellhead pressure is stable for 2 minutes, the foam sand-carrying liquid with a volume ratio of sand to foam sand-carrying liquid of 20% is injected. After the wellhead pressure is stable for 2 minutes, the next level of sand addition is started. Each level of sand addition concentration increases by 10% compared with the previous level, until the volume ratio of sand to foam sand-carrying liquid is 70%, and it is stable for 2 minutes. If the pressure rises by more than 2MPa within 2 minutes, stop adding sand and inject 10m of foam sand-carrying liquid without sand. 3 , observe the changes in pumping pressure. If the pressure tends to be stable, continue to add sand according to the construction design until the construction is completed and the design requirements are met; if the pressure continues to rise, stop the construction; Step S5 is as follows: After the sand is added, the foaming sand-carrying liquid without sand and nitrogen is injected according to the designed displacement amount. The displacement amount formula is: in, is the displacement fluid volume, is the surface pipeline volume, is the tubing volume; the injection rate is 0.5m 3 / min, the injection pressure shall not exceed 10MPa; on-site technicians need to adjust the construction displacement according to the wellhead pressure.
2. The method for oil well sand control using nitrogen foam according to claim 1, characterized in that: The steps of S6 are as follows: lift the tubing to the original hanging weight, rotate the tubing column 30 times forward to achieve tubing column release, and lift the tubing to 1m above the wellhead; close the tubing and casing valves for 24 hours. If the tubing and casing wellhead pressure is not 0, install an oil nozzle at the tubing outlet, and select the corresponding oil nozzle diameter according to the tubing wellhead pressure, and spray until the wellhead pressure is 0.
3. The method for oil well sand control using nitrogen foam according to claim 2, characterized in that: Step S7 is as follows: backwash the well with formation water in this area, with the formation water injection rate being 300-600L / min, until the returned fluid has the same fluidity as the injected formation water; after the well washing is completed, the hand-release string is removed.
4. The method for oil well sand control using nitrogen foam according to claim 3, characterized in that: The steps of S8 are as follows: lower a sand flushing string containing at least 80m of Φ42mm flushing pipe and oil pipe to re-explore the sand surface of the central pipe. If there is sand, backwash the sand until the thread plug is blocked; use formation water in this area for sand flushing, with an injection rate of 300-600L / min, until the returned fluid is consistent with the injected formation water, then pull out the sand flushing string in the well and the construction is completed.
Citation Information
Patent Citations
Sand-preventing filling method and equipment for oil and gas well
CN102434131A