Rock core displacement device and method

Abstract

The invention belongs to the field of oil exploitation, and discloses a rock core displacement device and method.The rock core displacement device comprises an injection system, a displacement system, a pressure collecting system and an extraction metering system.The injection system comprises a constant-flux pump and a displacement piston container, and an outlet of the constant-flux pump is connected with an inlet of the displacement piston container through a pipeline; an outlet of the displacement piston container is connected with an inlet of the displacement system through a pipeline, an outlet of the displacement system is connected with the extraction metering system through a pipeline, and the displacement system is connected with the pressure collecting system. According to the rock core displacement device and method, the problem of end face blockage can be solved, the real conditions of a shaft and an underground reservoir can be accurately simulated, the accuracy and precision of indoor experiments are improved, and a theoretical basis is provided for application of the scale of an oil field and a mine field.

Description

Technical Field

[0001] The invention belongs to the field of petroleum exploitation, and in particular relates to a core displacement device and method. Background Art

[0002] Low permeability reservoirs generally have strong heterogeneity. Many low permeability reservoirs are dual-porosity media with relatively well-developed fractures. Due to the differences in storage and seepage between fractures and matrix, if conventional water injection development is adopted, water will easily flow along the fractures, resulting in flooding of oil wells and a rapid increase in water content. Therefore, it is necessary to use deep displacement technology to redistribute the liquid flow deep in the formation using displacement agents. The core displacement experiment is a recognized method for studying the flow of fluids in the core, which can effectively evaluate the various performance indicators of the displacement agent. The existing core displacement experiment methods mainly have the following problems: (1) The displacement agent particles are prone to sinking when injected under static conditions; (2) The end effect is serious and the particles are piled up in large quantities, which makes it impossible to carry out the experiment smoothly; (3) It is impossible to simulate the actual situation of the wellbore and underground reservoir. The actual injection process is different: (1) The wellbore is in a turbulent environment, which stirs and disperses the displacement agent and prevents it from accumulating; (2) The perforation aperture is much larger than the pore aperture, which provides initial dispersion of the displacement agent; (3) The displacement agent enters the large pores near the wellbore, further dispersing it and expanding the seepage area.

[0003] Therefore, a core displacement device and method were developed to solve the problem of end face blockage, and can accurately simulate the actual conditions of the wellbore and underground reservoir, improve the accuracy and precision of indoor experiments, and provide a theoretical basis for application at the oil field mine scale. Summary of the invention

[0004] In order to overcome the defects of the above-mentioned prior art, the purpose of the present invention is to provide a core displacement device and method, which can effectively solve the problem of end face blockage, and can accurately simulate the actual situation of the wellbore and underground reservoir, improve the accuracy and precision of indoor experiments, and provide a theoretical basis for application at the oil field mine scale.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A core displacement device includes an injection system, a displacement system, a pressure acquisition system and a production metering system.

[0007] The injection system includes a horizontal flow pump and a displacement piston container. The outlet of the horizontal flow pump is connected to the inlet of the displacement piston container through a pipeline. The outlet of the horizontal flow pump is provided with a valve. The outlet of the displacement piston container is connected to the inlet of the displacement system through a pipeline. The outlet of the displacement system is connected to the production metering system through a pipeline. The outlet and inlet of the displacement system are both provided with valves. The displacement system is connected to the pressure collection system.

[0008] Furthermore, the displacement piston container is three parallel liquid containers, the outlets and inlets of the three liquid containers are provided with valves, and the three liquid containers are used to add simulated oil, simulated formation water and displacement agent respectively.

[0009] Furthermore, the displacement system includes a core holder, and the core holder fixes and installs the target formation core sample through a core rubber plug and a rubber sleeve end plug.

[0010] Furthermore, the displacement system also includes a turbulence generating slot, a simulated perforating device and a high permeability core (7), wherein the turbulence generating slot, the simulated perforating device, the high permeability core and the target formation core sample are fixedly installed in the core holder in sequence, and the turbulence generating slot is located on the side close to the inlet of the displacement system.

[0011] Furthermore, the metering system comprises a collecting container, and the collecting container is connected to the outlet of the core holder through a pipeline.

[0012] Furthermore, the pressure acquisition system includes a pressure sensor and a computer. The pressure sensor is arranged on the target formation core sample, and the pressure sensor and the computer are signal-connected.

[0013] Furthermore, a plurality of pressure sensors are evenly distributed along the axial direction on the outer surface of the target formation core sample.

[0014] Furthermore, the simulated perforating device is a columnar structure with a plurality of horizontal through holes arranged at the axis.

[0015] On the other hand, the present invention also discloses a core displacement method, which is based on the above core displacement device.

[0016] Further, the core flooding method includes:

[0017] Fill the three displacement piston containers with simulated oil, simulated formation water and displacement agent respectively, and start the pressure acquisition system;

[0018] The displacement system is evacuated, and then simulated oil or simulated formation water or displacement agent is injected into the displacement system at a constant rate;

[0019] After the pressure sensor readings and the outlet fluid of the displacement system are stable, the performance parameters of the target formation core sample and the displacement agent are calculated.

[0020] Technical effects and advantages of the present invention:

[0021] (1) The present invention uses a turbulence generating tank to ultrasonically stir the displacement agent, which can effectively simulate wellbore conditions and avoid the sinking of the displacement agent under static conditions.

[0022] (2) The present invention uses a simulated perforating device to preliminarily disperse the displacement agent, which can effectively simulate the perforation section in the actual reservoir.

[0023] (3) The present invention uses high permeability cores to further disperse the displacement agent, which can effectively simulate the near-wellbore area and expand the seepage area.

[0024] (4) The present invention can effectively solve the problem of end face blockage by providing a turbulence generating groove, a simulated perforating device and a high permeability core, and can accurately simulate the actual conditions of the wellbore and underground reservoir, thereby improving the accuracy and precision of indoor experiments.

[0025] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a structural schematic diagram of the core displacement device of the present invention;

[0027] Figure 2 It is a schematic structural diagram of the simulated perforating device of the present invention.

[0028] Figure numerals: 1. horizontal flow pump; 2. displacement piston container; 3. core holder; 4. target formation core sample; 5. turbulence generating groove; 6. simulated perforating device; 7. high permeability core; 8. collection container; 9. pressure sensor. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] like Figure 1 As shown, the present invention provides a core displacement device, including an injection system, a displacement system, a pressure acquisition system and a production metering system.

[0031] The injection system includes a horizontal flow pump 1 and a displacement piston container 2. The outlet of the horizontal flow pump 1 is connected to the inlet of the displacement piston container 2 through a pipeline. The outlet of the horizontal flow pump 1 is provided with a valve. The outlet of the displacement piston container 2 is connected to the inlet of the displacement system through a pipeline. The outlet of the displacement system is connected to the production metering system through a pipeline. The outlet and inlet of the displacement system are both provided with valves. The displacement system is connected to the pressure acquisition system.

[0032] In some embodiments of the present invention, the displacement piston container 2 is three parallel liquid containers, the outlets and inlets of the three liquid containers are provided with valves, and the three liquid containers are used to add simulated oil, simulated formation water and displacement agent respectively.

[0033] In some embodiments of the present invention, the displacement system includes a core holder 3, and the core holder is fixedly mounted with a target formation core sample 4 through a core rubber plug and a rubber sleeve end plug.

[0034] In some embodiments of the present invention, the displacement system also includes a turbulence generating groove 5, a simulated perforating device 6 and a high permeability core 7. The turbulence generating groove 5, the simulated perforating device 6, the high permeability core 7 and the target formation core sample 4 are fixedly installed in the core holder in sequence, and the turbulence generating groove 5 is located on the side close to the inlet of the displacement system.

[0035] In some embodiments of the present invention, the metering system comprises a collecting container 8 , which is connected to the outlet of the core holder 3 via a pipeline.

[0036] In some embodiments of the present invention, the pressure acquisition system includes a pressure sensor 9 and a computer. The pressure sensor 9 is disposed on the target formation core sample 4, and the pressure sensor 9 is signal-connected to the computer.

[0037] In some embodiments of the present invention, a plurality of pressure sensors are evenly distributed along the axial direction on the outer surface of the target formation core sample, and are used to collect the pressure values ​​along the target formation core sample.

[0038] In some embodiments of the present invention, Figure 2 As shown, the simulated perforating device is a columnar structure with a plurality of horizontal through holes arranged at the axis.

[0039] In another aspect, the present invention discloses a core displacement method, which is based on the core displacement device mentioned above.

[0040] In some embodiments of the present invention, the core flooding method includes:

[0041] Fill the three displacement piston containers with simulated oil, simulated formation water and displacement agent respectively, and start the pressure acquisition system;

[0042] The displacement system is evacuated, and then simulated oil or simulated formation water or displacement agent is injected into the displacement system at a constant rate;

[0043] After the pressure sensor readings and the outlet fluid of the displacement system are stable, the performance parameters of the target formation core sample and the displacement agent are calculated.

[0044] Polymer microspheres are deep flooding and plugging materials developed in recent years. Because of their good retention in pores, they increase the internal specific surface area and reduce the permeability of high permeability layers, and can meet the requirements of injection, blocking and migration of flooding agents. In order to better explain this solution, the following examples are provided to evaluate the deep flooding performance indicators of polymer microspheres and the extent of increased recovery in the core using the core displacement device of the present invention.

[0045] Example 1

[0046] Evaluate the performance indicators of deep flooding of polymer microspheres.

[0047] S1: Preparation stage: Connect the injection system, displacement system, pressure acquisition system and production metering system according to the device design structure, install the turbulence generating tank 5, simulated perforating device 6, high permeability core 7 and target formation core 4 in the core holder 3, fill the three displacement piston containers 2 with simulated oil, simulated formation water and displacement agent respectively, and start the pressure acquisition system.

[0048] S2: Water flooding stage: evacuate the displacement system, start the horizontal flow pump 1, inject simulated formation water into the displacement system at a constant rate of 1 mL / min to saturate it, and then collect the output fluid of the displacement system. After the pressure of the first pressure sensor 9 close to the inlet side of the displacement system is stable for more than half an hour and the output fluid of the outlet of the displacement system is stable, calculate the initial water permeability Kw according to the Darcy formula, weigh the total weight of the target formation core 4, and calculate the pore volume PV and porosity φ of the target formation core 4.

[0049] S3: Chemical flooding stage: Start the horizontal flow pump 1, inject the control agent into the displacement system at a constant rate of 1 mL / min, record the readings of each pressure sensor 9 along the target formation core 4, where the change of injection pressure over time can be used to examine the injectability, continuously sample the output fluid of the displacement system every 10 minutes, and stop injecting the control agent after injecting 1 PV.

[0050] S4: Subsequent water flooding stage: Start the horizontal flow pump 1, inject simulated formation water into the displacement system at a constant rate of 1 mL / min to saturate it, and then collect the output fluid of the displacement system. After the pressure of the first pressure sensor 9 close to the inlet side of the displacement system is stable for more than half an hour and the output fluid of the outlet of the displacement system is stable, calculate the water-measured permeability K2 according to the Darcy formula, examine the plugging strength of the displacement agent, and calculate indicators such as breakthrough pressure gradient, resistance coefficient, residual resistance coefficient, and plugging rate.

[0051] Among them, permeability K refers to the ability of rock to allow fluid to pass through under a certain pressure difference, and its expression is:

[0052]

[0053] Where K is the permeability, μm2 ; Q is flow rate, cm 3 ; μ is viscosity, mPa·s; L is core length, cm; A is core cross-sectional area, cm 2 ; ΔP is the pressure difference during the water-agent flooding stage, MPa.

[0054] Drag coefficient R F It refers to the ratio of water mobility to the mobility of the displacement agent, which is used to characterize the ability of the displacement agent to reduce the flow ratio. Its expression is:

[0055]

[0056] In the formula, R F is the resistance coefficient; w is the fluidity of water, μm 2 / (mPa·s);λ p is the fluidity of the displacement agent, μm 2 / (mPa·s);μ w is the viscosity of water, mPa·s; k w is the permeability in the water flooding stage, μm 2 ;μ p is the viscosity of the displacement agent, mPa·s; k p is the permeability of the drug flooding stage, μm 2 ; ΔP1 is the pressure difference during the chemical flooding stage, MPa; ΔP w is the pressure difference during the water-agent flooding stage, MPa.

[0057] Residual resistance coefficient R k It refers to the ratio of the water phase permeability of the oil layer before and after the displacement of the displacement agent, which is used to characterize the ability of the displacement agent to reduce the permeability. Its expression is:

[0058]

[0059] In the formula, R k is the residual resistance coefficient; k2 is the permeability in the subsequent water flooding stage, μm 2 ; ΔP 2 is the pressure difference in the subsequent water flooding stage, MPa.

[0060] The plugging rate η refers to the percentage of water phase permeability reduction before and after the displacement agent is flooded. It is used to characterize the ability of the displacement agent to plug the core. Its expression is:

[0061]

[0062] Where η is the plugging rate, %.

[0063] Example 2

[0064] Evaluate the extent of enhanced oil recovery using polymer microspheres in core.

[0065] S1: Preparation stage: Connect the injection system, displacement system, pressure acquisition system and production metering system according to the device design structure, install the turbulence generating tank 5, simulated perforating device 6, high permeability core 7 and target formation core 4 in the core holder 3, fill the three displacement piston containers 2 with simulated oil, simulated formation water and displacement agent respectively, and start the pressure acquisition system.

[0066] S2: Vacuum the displacement system, start the horizontal flow pump 1, inject simulated formation water into the displacement system at a constant rate of 1 mL / min to saturate it, and then collect the output fluid of the displacement system. After the pressure of the first pressure sensor 9 near the inlet of the displacement system is stable for more than half an hour and the output of the displacement system outlet is stable, calculate the initial water permeability K according to the Darcy formula l , weigh the total weight of the target formation core 4, and calculate the pore volume PV and porosity φ of the target formation core 4.

[0067] S3: After the parameters of the target formation core 4 calculated in S2 are qualified, simulated oil is injected into the displacement system to saturate the target formation core 4, and the saturated target formation core 4 is aged in an oven (at formation temperature) for more than 24 hours.

[0068] S4: Water flooding stage: install the target formation core 4 after S3 aging back into the core holder 3, start the horizontal flow pump 1, inject simulated formation water into the target formation core 4 after aging at a constant rate of 1 mL / min, collect the produced fluid, and stop the injection when the water content of the produced fluid reaches 98%.

[0069] S5: Agent flooding stage: Start the horizontal flow pump 1, inject a certain PV number of injection and displacement agent into the aged target formation core 4 at a constant rate of 1 mL / min, and record the readings of each pressure sensor 9 along the aged target formation core 4.

[0070] S6: Subsequent water flooding stage: Start the horizontal flow pump 1, inject simulated formation water into the aged target formation core 4 at a constant rate of 1 mL / min, collect the produced fluid, and stop the injection when the water content of the produced fluid reaches 98%, and calculate the enhanced oil recovery value.

[0071] The oil displacement efficiency refers to the ratio of the oil volume displaced to the original oil content, and its expression is:

[0072]

[0073]

[0074] EOR=E2-E1

[0075] Where, E1 is the oil recovery efficiency in the water flooding stage, %, E2 is the oil recovery efficiency in the subsequent water flooding stage, %, EOR is the enhanced oil recovery value, %, O1 is the cumulative oil production in the water flooding stage, cm 3 , O2 is the cumulative oil production in the subsequent water flooding stage, cm 3 .

[0076] In summary, the present invention can effectively solve the problem of end face blockage by arranging a turbulence generating groove, a simulated perforating device and a high permeability core in the core displacement device, and can accurately simulate the real situation of the wellbore and underground reservoir, thereby improving the accuracy and precision of indoor experiments.

[0077] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A core displacement device, characterized in that: Including injection system, displacement system, pressure acquisition system and production metering system, The injection system comprises a horizontal flow pump (1) and a displacement piston container (2), the outlet of the horizontal flow pump (1) is connected to the inlet of the displacement piston container (2) via a pipeline, the outlet of the horizontal flow pump (1) is provided with a valve, the outlet of the displacement piston container (2) is connected to the inlet of the displacement system via a pipeline, the outlet of the displacement system is connected to the production metering system via a pipeline, the outlet and inlet of the displacement system are both provided with valves, and the displacement system is connected to the pressure acquisition system.

2. A core displacement device according to claim 1, characterized in that: The displacement piston container (2) is three liquid containers connected in parallel, and the outlets and inlets of the three liquid containers are all provided with valves. The three liquid containers are used to add simulated oil, simulated formation water and displacement agent respectively.

3. A core displacement device according to claim 1, characterized in that: The displacement system comprises a core holder (3), and the core holder is used to fix and install a target formation core sample (4) via a core rubber plug and a rubber sleeve end plug.

4. A core displacement device according to claim 3, characterized in that: The displacement system further comprises a turbulence generating groove (5), a simulated perforating device (6) and a high permeability core (7), wherein the turbulence generating groove (5), the simulated perforating device (6), the high permeability core (7) and the target formation core sample (4) are fixedly installed in the core holder in sequence, and the turbulence generating groove (5) is located on a side close to the inlet of the displacement system.

5. A core displacement device according to claim 4, characterized in that: The metering system comprises a collecting container (8), and the collecting container (8) is connected to the outlet of the core holder (3) through a pipeline.

6. A core displacement device according to claim 5, characterized in that: The pressure acquisition system comprises a pressure sensor (9) and a computer. The pressure sensor (9) is arranged on the target formation core sample (4). The pressure sensor (9) and the computer are signal-connected.

7. A core displacement device according to claim 6, characterized in that: The plurality of pressure sensors are evenly distributed along the axial direction on the outer surface of the target formation core sample.

8. A core displacement device according to claim 4, characterized in that: The simulated perforating device is a columnar structure with a plurality of horizontal through holes arranged at the axis.

9. A core flooding method, characterized in that: The method is based on the core displacement device according to any one of claims 1-8.

10. A core flooding method according to claim 9, characterized in that: include: Fill the three displacement piston containers with simulated oil, simulated formation water and displacement agent respectively, and start the pressure acquisition system; The displacement system is evacuated, and then simulated oil or simulated formation water or displacement agent is injected into the displacement system at a constant rate; After the pressure sensor readings and the outlet fluid of the displacement system are stable, the performance parameters of the target formation core sample and the displacement agent are calculated.

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