Heavy oil hot lift testing device and method for deep well low-permeability reservoir
By designing a thermal lift testing device in a deep, low-permeability heavy oil reservoir, a high-temperature dynamic fluid is injected into the well and the mixture is separated and metered. This solves the problem of obtaining production data in deep, low-permeability oil reservoir testing and achieves efficient testing and accurate metering.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ZHANJIANG BRANCH OF CHINA NATIONAL OFFSHORE OIL CORP
- Filing Date
- 2026-03-13
- Publication Date
- 2026-05-12
AI Technical Summary
Existing technologies make it difficult to accurately obtain production data in deep, low-permeability heavy oil reservoirs. Nitrogen injection through coiled tubing can easily cause cooling, and screw pumps have limited depth, making it impossible to effectively test deep, low-permeability reservoirs.
A thermal lift testing device for heavy oil in deep, low-permeability reservoirs is designed. High-temperature dynamic fluid is injected into the well through coiled tubing, keeping the wellbore at a high temperature to prevent the heavy oil from solidifying. A lift valve is used to mix the well fluid and separate and meter it, achieving efficient testing.
It enables the prevention of heavy oil solidification in deep, low-permeability reservoirs, reduces oil flow resistance, improves testing efficiency, and accurately obtains production data.
Smart Images
Figure CN122014187A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of oil well testing technology, and in particular to a thermal lift testing device and method for heavy oil in deep, low-permeability reservoirs. Background Technology
[0002] Current oil and gas exploration is gradually moving towards deeper and ultra-deep reservoirs, with low-permeability reservoirs and heavy oil reservoirs, which are characterized by low production and low grade, becoming the main areas for reserve discovery. These reservoirs are deeply buried, exhibiting low porosity and low permeability, resulting in high initiation pressures for oil flow. The high viscosity of heavy oil further increases these pressures, making it difficult to accurately obtain production data. Currently, well testing typically involves gas lift testing using nitrogen injection through coiled tubing. However, nitrogen injection easily cools the wellbore, making it unsuitable for heavy oil reservoir testing and unable to obtain accurate production data. Screw pump testing can use heating cables to heat the wellbore at a certain depth, but the depth of screw pump insertion is limited, preventing the creation of a larger production pressure differential during testing, thus affecting the accurate evaluation of these reservoirs and making it unsuitable for testing deep, low-permeability reservoirs. Therefore, a suitable testing method is urgently needed for deep, low-permeability, and heavy oil reservoirs to accurately obtain production data and guide the exploration and development of these reservoirs. Summary of the Invention
[0003] The purpose of this invention is to provide a thermal lift testing device for heavy oil in deep well low-permeability reservoirs, which can continuously inject high-temperature dynamic fluid into the well, maintain the wellbore at a high temperature, prevent heavy oil from solidifying, reduce oil flow resistance, and improve the testing efficiency of heavy oil.
[0004] Another objective of this invention is to provide a method for testing the thermal lift of heavy oil in deep, low-permeability reservoirs, which can continuously inject high-temperature dynamic fluid into the well, maintain the wellbore at a high temperature, prevent the heavy oil from solidifying, reduce oil flow resistance, and improve the efficiency of heavy oil testing.
[0005] To achieve the above objectives, the present invention adopts the following technical solution, including a surface device and a downhole tubing string; The surface device includes, in sequence, a coiled tubing assembly, a wellhead flow head, a surface safety valve, an oil nozzle manifold, a three-phase separator, a multi-stage oil-water separation system, a heating power system, a metering tank connected to the multi-stage oil-water separation system and the three-phase separator, and a water source tank connected to the heating power system; the heating power system is connected to the coiled tubing assembly via a main water flow pipe. The downhole tubing string includes a test tubing string, a packer disposed on the outer periphery of the test tubing string, and a lift valve disposed inside the test tubing string; the upper end of the test tubing string is connected to the lower end of the wellhead flow head and is set inside the production casing by the packer; the coiled tubing of the coiled tubing assembly extends into the test tubing string and is connected to the lift valve; a second annulus is provided between the coiled tubing and the test tubing string.
[0006] Preferably, the lifting valve includes: The outer circumference of the lifting valve outer cylinder is connected to the inner circumference of the test column; an inwardly tapering insertion part is provided at the lower part of the inner circumference of the lifting valve outer cylinder; The inner cylinder of the lifting valve is connected at its upper end to the continuous tubing. A contraction section with a gradually decreasing inner diameter is provided at the upper part of the inner cylinder. A downwardly extending throat is provided on the inner circumference of the contraction section. A downwardly extending outer wall is provided on the outer circumference of the contraction section. A nozzle is formed at the point where the inner diameter of the contraction section is smallest. An insertion portion adapted to the insertion portion is provided at the lower part of the outer wall. A first annular space is formed between the upper part of the outer wall and the outer cylinder of the lifting valve. A first fluid inlet is provided at the lower end of the throat. An annular space is formed between the outer wall and the throat. A first partition for dividing the annular space into upper and lower parts is provided in the lower middle part of the annular space. A second partition is provided in the lower middle part of the throat. The second liquid inlet is located on the side wall of the lower part of the first partition and the throat, and the starting end of the second liquid inlet is located below the second partition. The third liquid inlet is radially disposed on the side wall at the upper end of the throat. The mixture outlet is located above the second partition, passes radially through the throat, the first partition and the outer wall in sequence, and communicates with the first annulus.
[0007] Preferably, multiple sealing grooves are provided on the outer periphery of the insertion part, and a sealing ring is provided in the sealing groove to achieve a sealing fit between the insertion part and the plug-in part.
[0008] Preferably, the wellhead flow head is connected sequentially to a surface safety valve, an oil nozzle manifold, and a three-phase separator via pipelines. The surface safety valve is an emergency shut-off control valve. The oil nozzle manifold is used to regulate the flow rate of the mixture. The three-phase separator is used for preliminary separation of the mixture. The preliminarily separated natural gas is burned through a combustion arm connected to the outside of the ship or naturally dissipates. The preliminarily separated oil enters the metering tank through the first oil flow pipe and the main oil flow pipe. The preliminarily separated water enters the multi-stage oil-water separation system through the first water flow pipe. The multi-stage oil-water separation system performs further separation. The further separated oil enters the metering tank through the second oil flow pipe and the main oil flow pipe. The further separated water enters the heating power system through the second water flow pipe. The heating power system is used to meter the internal water volume and rapidly heat the flowing water to 60-70°C before pumping it out as high-pressure power fluid. It then enters the continuous tubing of the continuous tubing assembly through the main water flow pipe until it enters the inner cylinder of the lift valve. The water source tank is used to provide water to the heating power system or to drain water.
[0009] A method for testing the thermal lift of heavy oil in low-permeability reservoirs in deep wells, using the thermal lift testing device for low-permeability reservoirs in deep wells described above, includes the following steps: S1. The outer cylinder of the lifting valve is lowered into the well along with the test tubing and then set in the production casing by the packer. S2. Lower the continuous tubing and the inner cylinder of the lifting valve, and seal it with the outer cylinder of the lifting valve. S3. Start the heating power system, which heats the power fluid to 60~70℃ and continuously pumps the power fluid into the continuous oil pipe through a pumping pressure of 15~25MPa. S4. The well fluid and the power fluid are mixed in the lifting valve to form a mixture, which flows out through the wellhead flow head. S5. The mixture from the wellhead flow head passes sequentially through the surface safety valve, the nozzle manifold, and into the three-phase separator. Preliminary separation occurs in the three-phase separator. The preliminarily separated natural gas is burned through the combustion arm connected to the outside of the vessel or naturally dissipates. The preliminarily separated oil enters the metering tank, and the preliminarily separated water enters the multi-stage oil-water separation system. The multi-stage oil-water separation system performs further separation. The further separated oil enters the metering tank, and the further separated water enters the heating power system. The heating power system meters the internal water volume and rapidly heats the flowing water to 60-70°C before high-pressure pumping it out as power fluid, which enters the continuous tubing of the continuous tubing assembly through the main water flow pipe. S6. After the pumping stabilizes, the volume increments of oil and water are measured by the metering tank and the heating power system within time t hours, respectively, as ΔV. 油 and ΔV 水 , The daily crude oil production from the well test was then calculated as follows: The daily production of raw water from the oil well test was then calculated as follows: .
[0010] Preferably, the pumped-in stable temperature of the returned mixture reaches 50~60℃, and the mixture contains crude oil.
[0011] The beneficial effects of this invention are: continuous injection of high-temperature dynamic fluid into the well, maintaining the wellbore at a high temperature, preventing heavy oil from solidifying, reducing oil flow resistance, and improving the efficiency of heavy oil testing. Attached Figure Description
[0012] Figure 1 This is a schematic diagram of a thermal lift testing device for heavy oil in a deep well with low permeability reservoir according to the present invention.
[0013] Figure 2 This is a schematic diagram of the lifting valve in this invention. Detailed Implementation
[0014] The invention will now be described in further detail with reference to the accompanying drawings, so that those skilled in the art can implement it based on the description.
[0015] It should be understood that terms such as “having,” “comprising,” and “including” as used herein do not exclude the presence or addition of one or more other elements or combinations thereof.
[0016] like Figure 1-2 As shown, the present invention provides a thermal lift testing device for heavy oil in deep well low-permeability reservoirs, comprising: Including surface equipment and downhole tubing; The surface device includes, in sequence, a coiled tubing assembly 110, a wellhead flow head 120, a surface safety valve 130, an oil nozzle manifold 140, a three-phase separator 150, a multi-stage oil-water separation system 160, a heating power system 170, a metering tank 181 connected to the multi-stage oil-water separation system 160 and the three-phase separator 150, and a water source tank 182 connected to the heating power system 170; the heating power system 170 is connected to the coiled tubing assembly 110 via a main water flow pipe 196. The downhole tubing string includes a test tubing string 210, a packer 220 disposed on the outer periphery of the test tubing string 210, and a lift valve 230 disposed inside the test tubing string 210; the upper end of the test tubing string 210 is connected to the lower end of the wellhead flow head 120, and is set inside the production casing 2 by the packer 220; the coiled tubing 111 of the coiled tubing assembly 110 extends into the test tubing string 210 and is connected to the lift valve 230; a second annulus 211 is provided between the coiled tubing 111 and the test tubing string 210.
[0017] In another embodiment, the lifting valve 230 includes: an outer cylinder 231, the outer periphery of which is connected to the inner periphery of the test string 210; a recessed insertion portion 231a is provided at the lower part of the inner periphery of the outer cylinder 231; an inner cylinder 232, the upper end of which is connected to the continuous tubing 111; a contraction section 233 with a gradually decreasing inner diameter is provided at the upper part of the inner cylinder 232; a downwardly extending throat 234 is provided at the inner periphery of the contraction section 233; a downwardly extending outer wall 235 is provided at the outer periphery of the contraction section 233; a nozzle 236 is formed at the minimum inner diameter of the contraction section 233; an insertion portion 235a adapted to the insertion portion 231a is provided at the lower part of the outer wall 235; a first annulus 235b is formed between the upper part of the outer wall 235 and the outer cylinder 231; The lower end of the throat 234 is provided with a first liquid inlet 234a; an annular space is formed between the outer wall 235 and the throat 234, and a first partition 237 is provided in the lower middle part of the annular space to divide the annular space into upper and lower parts; a second partition 238 is provided in the lower middle part of the throat 234; a second liquid inlet 237a is provided on the side wall of the lower part of the first partition 237 and the throat 234, and the starting end of the second liquid inlet 237a is located below the second partition 238; a third liquid inlet 234b is radially provided on the side wall of the upper end of the throat 234; a mixed liquid outlet 237b is located above the second partition 238, and passes radially through the throat 234, the first partition 237 and the outer wall 235 in sequence, and communicates with the first annular space 235b.
[0018] In another embodiment, multiple sealing grooves are provided on the outer periphery of the insertion part 235a, and a sealing ring 239 is provided in the sealing groove to achieve a sealing fit between the insertion part 235a and the insertion part 231a.
[0019] In another embodiment, the wellhead flow head 120 is connected sequentially to a surface safety valve 130, an oil nozzle manifold 140, and a three-phase separator 150 via pipelines. The surface safety valve 130 is an emergency shut-off control valve, the oil nozzle manifold 140 is used to regulate the flow rate of the mixture, and the three-phase separator 150 is used for preliminary separation of the mixture. The preliminarily separated natural gas is burned through a combustion arm connected to the outside of the ship or naturally dissipates. The preliminarily separated oil enters the metering tank 181 through the first oil flow pipe 191 and the main oil flow pipe 192, and the preliminarily separated water enters the multi-stage oil-water separation system 1 through the first water flow pipe 193. 60. The multi-stage oil-water separation system 160 further separates the oil, which then enters the metering tank 181 through the second oil flow pipe 194 and the main oil flow pipe 192. The further separated water enters the heating power system 170 through the second water flow pipe 195. The heating power system 170 is used to meter the internal water volume and rapidly heat the flowing water to 60~70°C before pumping it out as high-pressure power fluid. The water then enters the continuous oil pipe 111 of the continuous oil pipe assembly 110 through the main water flow pipe 196 until it enters the inner cylinder 232 of the lifting valve. The water source tank 182 is used to provide water to the heating power system 170 or to drain water.
[0020] Example Taking well A in the offshore area as an example, the well depth is 3990m. The 9-5 / 8" production casing is run down to 3565m. The 8-1 / 2" open hole encounters a buried hill oil reservoir. The oil is heavy oil, which is semi-solid at room temperature and is difficult to flow naturally. The component analysis results show that the content of gum and asphaltene is as high as 43%.
[0021] A method for thermal lift testing of heavy oil in low-permeability reservoirs in deep wells includes the following steps: S1. The outer cylinder 231 of the lifting valve is lowered into the well along with the test tubing 210 and set in the production casing 2 by the packer 220. S2. Lower the continuous oil pipe 111 and the inner cylinder 232 of the lifting valve, and seal it with the outer cylinder 231 of the lifting valve; S3. Start the heating power system 170. The heating power system 170 heats the power fluid to 60~70°C and continuously pumps the power fluid into the continuous oil pipe 111 through a pumping pressure of 15~25MPa. S4. After the well fluid flows out of the formation, it enters the throat through the first inlet 234a, then enters the annular space above the first baffle 237a through the second inlet 237a, and finally reaches the third inlet 234b. After the power fluid enters the inner cylinder 232 of the lifting valve, it passes through the contraction section 233 and reaches the nozzle 236. As the inner diameter of the contraction section 233 gradually decreases, the flow rate of the power fluid gradually increases and the pressure decreases, drawing the well fluid from the third inlet 234b into the nozzle 236. The fluid mixes in the throat 234 above the second baffle 238 to form a mixed liquid. The mixed liquid passes through the mixed liquid outlet 234b, the first annulus 235b, and the second annulus 211, and reaches the wellhead flow head 120. S5. The mixture from the wellhead flow head 120 passes sequentially through the surface safety valve 130, the oil nozzle manifold 140, and enters the three-phase separator 150. The three-phase separator 150 performs preliminary separation of the mixture. The preliminarily separated natural gas is burned through the combustion arm connected to the outside of the ship or naturally dissipates. The preliminarily separated oil enters the metering tank 181 through the first oil flow pipe 191 and the main oil flow pipe 192. The preliminarily separated water enters the multi-stage oil-water separation system 160 through the first water flow pipe 193. The multi-stage oil-water separation system 160 further separates the oil and water. The further separated oil enters the metering tank 181 through the second oil flow pipe 195 and the main oil flow pipe 192, and the further separated water enters the heating power system 170 through the second water flow pipe 195. The heating power system 170 measures the internal water volume and rapidly heats the flowing water to 60~70°C before pumping it out as high-pressure power fluid. The water then enters the continuous oil pipe 111 of the continuous oil pipe assembly 110 through the main water flow pipe 196. S6. The pumped-in and returned mixed liquid temperature reaches 50~60℃. After the mixed liquid comes into contact with crude oil, during the 4-hour temperature injection period, the volume increase of oil and water is measured to be 12.8m³ through metering tank 181 and heating power system 170. 3 and 0.49m 3 Therefore, the daily crude oil production was calculated to be 76.8 m³. 3 / d and daily water production of 2.94m 3 / d.
[0022] In summary, the device and method for testing heavy oil thermal lift in deep well low-permeability reservoirs can continuously inject high-temperature dynamic fluid into the well, maintain the wellbore at a high temperature, prevent heavy oil from solidifying, reduce oil flow resistance, and improve the efficiency of heavy oil testing.
[0023] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.
Claims
1. A thermal lift testing device for heavy oil in low-permeability deep well reservoirs, comprising a surface device and a downhole tubing string, characterized in that: The surface device includes, in sequence, a coiled tubing assembly, a wellhead flow head, a surface safety valve, an oil nozzle manifold, a three-phase separator, a multi-stage oil-water separation system, a heating power system, a metering tank connected to the multi-stage oil-water separation system and the three-phase separator, and a water source tank connected to the heating power system; the heating power system is connected to the coiled tubing assembly via a main water flow pipe. The downhole tubing string includes a test tubing string, a packer disposed on the outer periphery of the test tubing string, and a lift valve disposed inside the test tubing string; the upper end of the test tubing string is connected to the lower end of the wellhead flow head and is set inside the production casing by the packer; the coiled tubing of the coiled tubing assembly extends into the test tubing string and is connected to the lift valve; a second annulus is provided between the coiled tubing and the test tubing string.
2. The deep well low-permeability reservoir heavy oil thermal lift testing device according to claim 1, characterized in that, The lifting valve includes: The outer circumference of the lifting valve outer cylinder is connected to the inner circumference of the test column; an inwardly tapering insertion part is provided at the lower part of the inner circumference of the lifting valve outer cylinder; The inner cylinder of the lifting valve is connected at its upper end to the continuous tubing. A contraction section with a gradually decreasing inner diameter is provided at the upper part of the inner cylinder. A downwardly extending throat is provided on the inner circumference of the contraction section. A downwardly extending outer wall is provided on the outer circumference of the contraction section. A nozzle is formed at the point where the inner diameter of the contraction section is smallest. An insertion portion adapted to the insertion portion is provided at the lower part of the outer wall. A first annular space is formed between the upper part of the outer wall and the outer cylinder of the lifting valve. A first fluid inlet is provided at the lower end of the throat. An annular space is formed between the outer wall and the throat. A first partition for dividing the annular space into upper and lower parts is provided in the lower middle part of the annular space. A second partition is provided in the lower middle part of the throat. The second liquid inlet is located on the side wall of the lower part of the first partition and the throat, and the starting end of the second liquid inlet is located below the second partition. The third liquid inlet is radially disposed on the side wall at the upper end of the throat. The mixture outlet is located above the second partition, passes radially through the throat, the first partition and the outer wall in sequence, and communicates with the first annulus.
3. The deep well low-permeability reservoir heavy oil thermal lift testing device according to claim 2, characterized in that: Multiple sealing grooves are provided on the outer periphery of the insertion part, and a sealing ring is provided in the sealing groove to achieve a sealing fit between the insertion part and the plug-in part.
4. The thermal lift testing device for heavy oil in low-permeability reservoirs in deep wells according to claim 1, characterized in that: The wellhead flow head is connected sequentially to a surface safety valve, an oil nozzle manifold, and a three-phase separator via pipelines. The surface safety valve is an emergency shut-off control valve. The oil nozzle manifold is used to regulate the flow rate of the mixture. The three-phase separator is used for preliminary separation of the mixture. The preliminarily separated natural gas is burned through a combustion arm connected to the outside of the ship or naturally dissipates. The preliminarily separated oil enters the metering tank through the first oil flow pipe and the main oil flow pipe. The preliminarily separated water enters the multi-stage oil-water separation system through the first water flow pipe. The multi-stage oil-water separation system performs further separation. The further separated oil enters the metering tank through the second oil flow pipe and the main oil flow pipe. The further separated water enters the heating power system through the second water flow pipe. The heating power system is used to meter the internal water volume and rapidly heat the flowing water to 60~70°C before pumping it out as high-pressure power fluid. It then enters the continuous tubing of the continuous tubing assembly through the main water flow pipe until it enters the inner cylinder of the lifting valve. The water source tank is used to provide water to the heating power system or for drainage.
5. A method for testing the thermal lift of heavy oil in a deep well with low permeability, using the thermal lift testing device for heavy oil in a deep well with low permeability as described in claims 1-4, comprising the following steps: S1. The outer cylinder of the lifting valve is lowered into the well along with the test tubing and then set in the production casing by the packer. S2. Lower the continuous tubing and the inner cylinder of the lifting valve, and seal it with the outer cylinder of the lifting valve. S3. Start the heating power system, which heats the power fluid to 60~70℃ and continuously pumps the power fluid into the continuous oil pipe through a pumping pressure of 15~25MPa. S4. The well fluid and the power fluid are mixed in the lifting valve to form a mixture, which flows out through the wellhead flow head. S5. The mixture from the wellhead flow head passes sequentially through the surface safety valve, the nozzle manifold, and into the three-phase separator. Preliminary separation occurs in the three-phase separator. The preliminarily separated natural gas is burned through the combustion arm connected to the outside of the vessel or naturally dissipates. The preliminarily separated oil enters the metering tank, and the preliminarily separated water enters the multi-stage oil-water separation system. The multi-stage oil-water separation system performs further separation. The further separated oil enters the metering tank, and the further separated water enters the heating power system. The heating power system meters the internal water volume and rapidly heats the flowing water to 60-70°C before high-pressure pumping it out as power fluid, which enters the continuous tubing of the continuous tubing assembly through the main water flow pipe. S6. After the pumping stabilizes, the volume increments of oil and water are measured by the metering tank and the heating power system within time t hours, respectively, as ΔV. 油 and ΔV 水 , The daily crude oil production from the well test was then calculated as follows: The daily production of raw water from the oil well test was then calculated as follows: 。 6. The method for testing the thermal lift of heavy oil in low-permeability reservoirs in deep wells according to claim 5, characterized in that: The pumped-in mixture is stabilized when the temperature of the returned mixture reaches 50~60℃, and crude oil is visible in the mixture.