CN114460120A - Simulation experiment device and method for dense oil imbibition replacement based on nuclear magnetic resonance - Google Patents
Simulation experiment device and method for dense oil imbibition replacement based on nuclear magnetic resonance Download PDFInfo
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- G01N15/0826—Investigating permeability by forcing a fluid through a sample and measuring fluid flow rate, i.e. permeation rate or pressure change
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- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/02—Details not specific for a particular testing method
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- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/02—Details not specific for a particular testing method
- G01N2203/022—Environment of the test
- G01N2203/0236—Other environments
- G01N2203/0242—With circulation of a fluid
Abstract
The invention provides a compact oil imbibition replacement simulation experiment device and a compact oil imbibition replacement simulation experiment method based on nuclear magnetic resonance, which comprises an annular pressure maintaining system, a heating system, a rock core clamping system, a low-field nuclear magnetic resonance analyzer, a displacement system and a liquid receiving system. The method overcomes the defects that the conventional spontaneous imbibition experiment can not simulate the imbibition well-closing process under the stratum condition, can not realize continuous monitoring of the oil-water distribution condition of imbibition displacement, and defines the micro process of imbibition displacement.
Description
Technical Field
The invention belongs to the technical field of fracturing of low-permeability oil and gas fields, and particularly relates to a simulation experiment device and method for compact oil imbibition displacement based on nuclear magnetic resonance.
Background
The Chinese dense oil resource reserves are abundant, are the main resource foundation for increasing the reserves and stabilizing the yield of the Chinese crude oil in future and are mainly distributed in basins such as Erdos, quasi-Sacurel, Songliao, Bohai Bay, and Diesel wood. At present, good construction and production potentials are shown in the China's oil Changqing Longdong compact oil field, the Quercoll basin Jimusala depression, the Dagang oil field Candong depression and the like. Shale oil exploration evaluation is carried out on China petrochemicals in Qiyang depression, dwarasy in Fuxing areas of Chuandong, ancient near systems of basin in Jianhan, Qitong depression in North Suo and the like, and great breakthrough of shale oil exploration is realized in partial areas. In order to efficiently develop compact oil, oil and gas resources, a horizontal well volume fracturing mode becomes the first choice, volume fracturing forms a complex fracture network structure, fracturing fluid enters a fracture through an opened seepage channel, the fracturing fluid and crude oil in a matrix are subjected to imbibition displacement under the action of capillary force under the action of pressure, and the crude oil is lifted to the ground through a fracture with high seepage capacity under the action of natural pressure or mechanical lifting. However, for a shallow fractured reservoir with three low zones (low permeability, low pressure and low abundance), the volume fracturing oil well is difficult to take effect due to insufficient natural energy of the natural reservoir, has large water-breakthrough risk and low yield. Aiming at the oil reservoir with three low levels, researches find that a composite yield increasing technology of pre-pressure energy supplement, fracturing modification and soaking imbibition displacement becomes a main technology of compact oil development, wherein the soaking imbibition displacement is a key link of the technology, and researches find that the soaking imbibition displacement mechanism of the compact reservoir is that the pressure of a fracture water phase (water injection, fracturing fluid and fracturing fluid (containing oil displacement agent)) is greater than that of a matrix water phase in a post-pressure soaking stage, the water phase in the fracture enters the matrix under the action of capillary force, the pressure of a fracture oil phase is less than that of the matrix oil phase, oil flows into the fracture from the matrix, and the matrix and the fracture are subjected to oil-water imbibition displacement.
In order to deeply understand the mechanism of 'soaking, imbibition and displacement', researchers successively develop a device and a method for researching a compact oil imbibition and displacement experiment in a laboratory, mainly comprising a volume method and a mass method, wherein the volume method (such as an imbibition bottle method) is to soak an oil-containing rock core in an imbibition and displacement liquid, and test the displacement efficiency by testing the volume of oil which is imbibed and displaced in a certain time and enters a capillary tube, but the volume method can only measure the oil mass which is exuded and separated from a rock sample, and is difficult to measure the volume of oil beads which are exuded and attached to the wall of the rock sample, so that the measured imbibition and displacement efficiency has larger errors; secondly, the volume method can only be carried out under the conditions of normal temperature and normal pressure, and cannot simulate the seepage and absorption under the formation condition; and the oil quantity entering the capillary tube in different time can be measured only, and the micro process of imbibition displacement cannot be determined. The mass method is to measure the mass change of the rock core in the water phase by using a precision balance (by using the difference between oil and water density) to calculate the oil amount of imbibition displacement, and can adopt a manual counting mode and a computer automatic counting mode, and can also simulate the formation environment by constant temperature; but the vibration or the temperature change of the mass method in the experimental process can cause great influence on the experimental result; the precise balance connected with the rock core cannot be sealed, so that the pressure of the stratum cannot be simulated; in addition, the imbibition process can only observe the imbibition displacement state of the surface of the core in a window photographing mode, and the imbibition displacement process and state inside the core cannot be clear.
The low-field nuclear magnetic resonance technology is widely applied to research in various fields of oil and gas reservoir development with the advantages of rapidness, no damage and high sensitivity, and can quantitatively represent the content and migration characteristics of hydrogen fluid in a rock core under different conditions. The nuclear magnetic resonance technology is used for the research of imbibition, and mainly obtains the volume of the micro-pore imbibition liquid of the rock core by detecting the content change of hydrogen ions in the pores of the rock core at different moments, and explores the migration rule of the fracturing liquid under the imbibition action in real time. The patent (CN 109682850A) discloses a nuclear magnetic resonance testing device for imbibition experiments and an experimental method, which mainly adopt a simplified nuclear magnetic resonance device, place a rock core in a rock core holder, carry out dynamic imbibition through displacement of a advection pump, measure produced liquid at the tail end by a balance, and scan pressurized imbibition to obtain images. This method does not simulate the temperature and pressure conditions of the formation. The patent (CN 209460105U) discloses a visual pressurized rock core imbibition experimental device based on nuclear magnetic resonance, and the device is characterized in that liquid is pumped into a cavity similar to an imbibition bottle through a advection pump, a rock core is placed in the cavity, and an imbibition process image is obtained in an additional nuclear magnetic mode. The method can not measure the change of oil quantity, only can scan the change of microscopic images in the spontaneous imbibition process, and can not simulate the temperature and pressure conditions of the stratum. The patent (CN 111751397A) discloses a shale imbibition core holder for a nuclear magnetic resonance system, and proposes that a holder cavity assembly is made of nonmagnetic metal titanium steel and a high-temperature and high-pressure resistant nonmetal material, so that the influence on a nuclear magnetic field can be effectively avoided, but an experimental method is not given. Patent (CN 111323834 a) discloses an imbibition device for spontaneous imbibition by nuclear magnetic resonance technology, which utilizes the pressure difference of siphon effect to inject liquid into the cavity of imbibition bottle, places the core in the cavity of imbibition bottle, and obtains the image of spontaneous imbibition process by means of additional nuclear magnetism. The method can not measure the change of oil quantity, only can scan the change of microscopic images in the spontaneous imbibition process, and can not simulate the temperature and pressure conditions of the stratum. In the 05 th stage of 2015, the method adopted by the special oil and gas reservoir for researching the shale spontaneous imbibition process based on the nuclear magnetic resonance technology is as follows: and respectively measuring the initial oil content state of the rock sample by using nuclear magnetism, then carrying out nuclear magnetism measurement on the sample after the sample is imbibed in a conventional container, and calculating the oil displacement efficiency of the oil separated from the rock core and observing the distribution rule of the oil in the rock core by using the nuclear magnetism test results before and after the sample is imbibed. However, the method still has the problems that the experimental conditions are normal temperature and normal pressure, the imbibition and the scanning image separation are adopted, and the underground real imbibition process cannot be continuously monitored and reflected. The Zhuyunxuan, published in 2021, 7 months in the literature of 'computational physics' for studying the imbibition rule and the imbibition dynamic distribution of Longmaxi shale in Pengshui region; wang Chenguang, published in 36 years in "West An college of Petroleum institute" on the literature "spontaneous imbibition characteristics under different boundary conditions of tight sandstone reservoir"; the document 'shale pressurized imbibition nuclear magnetic resonance response characteristic experimental study' published in the university of petroleum in southwest by the junior of xianwei 2019 and 12 months. The above documents utilize nuclear magnetic resonance technology to conduct spontaneous imbibition research, and the experimental conditions are normal temperature and normal pressure, and online test cannot be realized, and formation conditions cannot be simulated. The above-described phenomena monitored by nuclear magnetic resonance are spontaneous imbibition, and do not simulate the process of imbibition blind well under the stratum condition.
Disclosure of Invention
In order to solve the problems, the invention provides a simulation experiment device and a simulation experiment method for compact oil imbibition displacement based on nuclear magnetic resonance, which overcome the defect that the conventional spontaneous imbibition experiment can not simulate the imbibition well-closing process under the stratum condition, and provide a continuous change monitoring method for the well-closing pressure in the core-closing displacement process; provides a method for continuously monitoring oil-water distribution in the process of seeping and displacing of the blind well and defining the microscopic process of seeping and displacing.
In order to achieve the purpose, the technical scheme adopted by the invention for solving the technical problems is as follows: the utility model provides a compact oil imbibition replacement's simulation experiment device based on nuclear magnetic resonance which characterized in that: the system comprises a ring pressure maintaining system, a heating system, a rock core clamping system, a low-field nuclear magnetic resonance analyzer, a displacement system and a liquid receiving system, wherein the rock core clamping system is arranged in the low-field nuclear magnetic resonance analyzer and comprises a rock core holder and a pressurizing circulation cavity, the pressurizing circulation cavity is sleeved at the rock core of the rock core holder, the input end and the output end of the heating system are respectively connected with an input pipe and an output pipe of the pressurizing circulation cavity, the output end of the displacement system is connected with a fluid injection pipe of the rock core clamping system, a fluid recovery pipe of the rock core clamping system is connected with the liquid receiving system, the ring pressure maintaining system provides ring pressure for the rock core of the rock core holder, and the lateral confining pressure provided for the rock core and the heating system form the same loop.
According to the technical scheme, the displacement system comprises a liquid supplementing container, a constant-pressure constant-speed pump and an intermediate container which are sequentially connected, the intermediate container is connected with a fluid injection pipe of the core clamping system through a liquid inlet valve, and a fluid recovery pipe of the core clamping system is connected with the liquid receiving system through a liquid outlet valve.
The experimental device for simulating the tight oil imbibition and displacement based on nuclear magnetic resonance as claimed in claim 1 or 2, wherein: the low-field nuclear magnetic resonance analyzer comprises a control box and a computer, and the rock core holder is placed in a magnetic field generated by the low-field nuclear magnetic resonance analyzer.
According to the technical scheme, the ring pressure maintaining system comprises two sensors, an air source, a ring pressure tracking pump and a pressure display meter, wherein the two sensors can respectively read the fluid injection pressure of the core holder and the pressure of the fluid flowing out of the core holder, and the ring pressure tracking pump is respectively connected with a pipeline of the heating system and an input pipe of the pressurizing circulation cavity.
According to the technical scheme, the heating device comprises a circulating pump and two heating devices, and the pipelines on the two sides of the two heating devices are respectively provided with a vent valve.
A compact oil imbibition displacement simulation test method based on nuclear magnetic resonance is characterized in that:
s1, establishing an oil displacement rate of the pretreated rock core by using nuclear magnetic crude oil or diesel oil, carrying out seam formation by adopting a manual seam splitting mode, closing the rock core after seam formation, wrapping the rock core by using tin foil paper, and opening two ends of the rock core;
s2, placing the core in a core clamping system of the compact oil imbibition replacement simulation test device based on nuclear magnetic resonance as claimed in any one of claims 1 to 4, and during experiment, opening a liquid inlet valve of the core clamping system and closing a liquid outlet valve of the core clamping system;
s3, adding a imbibition liquid containing a manganese chloride solution as a displacement liquid into the imbibition liquid container for pressurization, wherein the heating system adopts fluorinated oil as a circulating medium;
s4, opening the low-field nuclear magnetic resonance analyzer, opening the heating system to enable the temperature to reach the simulated formation temperature, starting a constant flow pump of the displacement system, and stopping and closing the liquid inlet valve after the imbibition liquid is pressurized to the well closing pressure for simulating imbibition displacement;
s5, starting a ring pressure tracking system to slowly increase the confining pressure to be higher than the pressurizing pressure of the imbibition liquid, and scanning a rock core by adopting nuclear magnetism at intervals to obtain an oil-water distribution image in the imbibition displacement process;
and S6, after the well is closed, opening a liquid outlet valve to naturally release pressure until no liquid enters the metering system, and ending the experiment.
According to the technical scheme, a nuclear magnetic resonance device is used for simulating that the temperature of a stratum is between 60 and 120 ℃, the pressure pumping flow of a constant-pressure constant-flow pump in a displacement system is controlled to be between 0.1ml/min and 0.5ml/min, the pressure difference for simulating imbibition displacement is between 5MPa and 20MPa, the pressure pumping is stopped and a liquid inlet valve is closed after the imbibition displacement pressure is reached, the confining pressure is slowly increased to be 2 to 5MPa higher than the imbibition liquid pressure by a ring pressure tracking system, and the concentration range of the manganese chloride of the imbibition liquid is between 2.5 and 5.0 percent.
According to the technical scheme, the time for imbibing and smoldering the core is controlled to be between 10 and 30 hours, and the core is longitudinally scanned every 1 hour in the imbibing and replacing process.
According to the technical scheme, the pressure at different times can be read through the displacement front-stage pressure gauge in the stuffy core process, the change rule of the time and the pressure in the stuffy core process is further obtained, and the recovery ratio of imbibition displacement of the stuffy core at different times is calculated according to the initial oil displacement rate.
According to the technical scheme, the change rule of time and pressure in the stuffy core process is obtained and then the T is passed2And determining the oil displacement rate at different times according to the peak area of the relaxation time graph.
The invention has the beneficial effects that:
1) the invention provides a continuous on-line monitoring process of the stifled well imbibition displacement, a continuous change monitoring state diagram of the stifled well pressure in the stifled core displacement process, a continuous monitoring oil-water distribution diagram in the stifled well imbibition displacement process and a relative content of residual oil in different time in the simulated imbibition displacement process according to the peak area size of a relaxation time diagram of an image formed by nuclear magnetic resonance based on a nuclear magnetic resonance device capable of simulating the formation temperature and the stifled well pressure, the method overcomes the defects that the conventional spontaneous imbibition experiment (mass method and volume method) can not simulate the change of temperature and pressure in the closed well imbibition process and can not realize continuous monitoring of the microscopic state of oil-water distribution in the imbibition replacement process, the method makes up the defect that the conventional nuclear magnetic resonance research imbibition process depends on a natural imbibition or displacement mode, and provides a stuffy well imbibition displacement process for simulating fracture;
2) according to the invention, the stratum temperature and the confining pressure of the blind well core are simulated by a heating system and a ring pressure tracking system which take fluorinated oil as a circulating medium, wherein the fluorinated oil in a pipeline loop is heated in an electric heating mode, so that the core in nuclear magnetic resonance is heated to reach the simulated temperature, the nuclear magnetic resonance is not responded by the fluorinated oil, and the scanned image is not influenced, and meanwhile, the ring pressure required by core clamping can be provided by adjusting the pump speed of a circulating pump of a heating device, so that the simulated blind well seepage and energy absorption can be closer to the real blind well seepage and displacement environment of the stratum;
3) according to the invention, a natural rock core is adopted, an artificial crack is formed by a crack splitting mode, then the rock core is covered by the tinfoil paper, the crack generated after fracturing is simulated, a displacement or natural seepage mode is not adopted, but a liquid outlet valve is closed, a pressure is directly applied to a stuffy well through a constant flow pump, and then a liquid inlet valve is closed for stuffy well, so that the experimental method is closer to a real stratum stuffy well seepage replacement process, and the experimental effect accuracy is higher;
4) the simulation method provided by the invention can better simulate the actual permeation and replacement process of the compact oil, and can provide a new means and a new method for researching the permeation and replacement mechanism and the process of the compact oil.
Drawings
Fig. 1 is a schematic diagram of a nuclear magnetic resonance dense oil imbibition displacement simulation experiment apparatus according to an embodiment of the present invention.
Fig. 2 is a schematic diagram of a change rule of imbibition pressure with time according to an embodiment of the invention.
Fig. 3 is a diagram showing an oil-water distribution at the time of 1 hour of imbibition displacement according to an embodiment of the present invention.
FIG. 4 is a diagram showing an oil-water distribution at the time of 5 hours of imbibition displacement according to an embodiment of the present invention
FIG. 5 is a diagram showing the oil-water distribution at the time of 15 hours of imbibition displacement according to the embodiment of the present invention.
Fig. 6 is a graph of T2 relaxation times at different times according to an embodiment of the present invention.
In the figure: 1-a sensor; 2-a ring pressure tracking pump; 3-pressure display meter; 4-a heating device; 5-a circulating pump; 6-a magnet; 7-a back pressure system; 8-large container; 9-small container; 10-a core holder; 11-constant pressure constant flow pump; 12-a blow-down valve; 13-fluid infusion container; 14-a weighing chamber; 15-liquid inlet valve; 16-a port valve; 17-a pressurized circulation chamber; 18-a gas source; 19-pressure display gauge.
Detailed Description
In order to make the technical solutions and technical advantages of the present invention clearer, the following will make clear and complete descriptions of the technical solutions in the implementation process of the present invention with reference to the embodiments.
As shown in fig. 1, the nuclear magnetic resonance compact oil imbibition replacement simulation testing apparatus provided in this embodiment includes a ring pressure maintaining system, a heating system, a core holding system, a low-field nuclear magnetic resonance analyzer, a displacement system, and a liquid receiving system.
The low-field nuclear magnetic resonance analyzer further comprises a control box and a computer, the core holding system is arranged in the low-field nuclear magnetic resonance analyzer and comprises a core holder 10 and a pressurizing circulation cavity 17 which is sleeved at the core of the core holder, the pressurizing circulation cavity 17 is used for providing the temperature of a simulated formation and the confining pressure of a stifled well core for the core, the input end and the output end of the heating system are respectively connected with the input pipe and the output pipe of the pressurizing circulation cavity 17, the output end of the displacement system is connected with the fluid injection pipe of the core holder 10, the fluid recovery pipe of the core holder 10 is connected with the liquid receiving system, the annular pressure maintaining system provides lateral confining pressure for the core holder, and the lateral confining pressure provided for the core and the heating device are the same loop. The core holder 10 is a conventional art, and is not described herein.
The heating device comprises a circulating pump 5 and two heating devices 4, and emptying valves 12 are respectively arranged on pipelines at two sides of the two heating devices. The ring pressure maintaining system provides ring pressure for the core holder and comprises a sensor 1, an air source 18, a ring pressure tracking pump 2, a pressure display meter 3 and a pressure display meter 19, wherein the two sensors 1 can respectively read the fluid injection pressure and the fluid outflow pressure of the core holder, the ring pressure tracking pump 2 is respectively connected with the input end of a pressurizing circulation cavity 17 and a pipeline of a heating device and used for providing lateral confining pressure for the core, and the pressure is read through the pressure display meter 19. In this embodiment, the heating system and the ring pressure tracking pump that use fluorinated oil as the circulating medium simulate the formation temperature and the confining pressure of stifled well core, specifically are: fluorinated oil in the heating pipeline loop is heated in an electric heating mode, and then the core in the nuclear magnetic resonance is heated to reach the simulation temperature, the fluorinated oil does not respond to nuclear magnetic resonance and does not influence a scanning image, meanwhile, the circulating pressure of the air source 18 pressure and the circulating pump 5 is adjusted through the ring pressure tracking pump 2, the fluorinated oil is applied to the pressure under the combined action, and then the ring pressure required by the core in the holder is applied.
The liquid receiving system comprises a back pressure system 7 and a weighing chamber 14, which can read the volume of oil and water after the well is closed.
The embodiment also provides a compact oil imbibition displacement simulation experiment method based on nuclear magnetic resonance, which specifically comprises the following steps:
s1, pre-treating the core such as cutting, grinding, drying, testing permeability of gas logging (see table 1), and using 0 for the pre-treated core#The oil displacement rate is established by diesel oil, a manual seam splitting mode is adopted for seam making, after seam making is completed, the rock core is closed and wrapped by tin foil paper, and two ends of the rock core are opened;
s2, placing the core in the core clamping system 10 of the nuclear magnetic resonance testing device, and during the experiment, opening a liquid inlet valve 15 of the core clamping system and closing a liquid outlet valve 16 of the core clamping system;
s3, adding a seepage liquid containing a manganese chloride solution (the mass concentration range of the manganese chloride of the seepage liquid is 3.5%) into a seepage liquid container as a displacement liquid for pressurization, wherein the heating system adopts fluorinated oil as a circulating medium;
s4, opening the low-field nuclear magnetic resonance analyzer 6, opening a circulating pump 5 and a heating device 4 of a constant-temperature heating system to enable the temperature to reach 60 ℃ of the simulated formation temperature, starting a constant-pressure constant-flow pump 11, pumping imbibition liquid in a large container 8 and a small container 9 into a rock core of a rock core clamping system 10 at a constant flow rate of 0.1ml/min until the pressure of a pressure display table 3 reaches 20MPa, and then stopping and closing an inlet valve 15;
s5, starting a ring pressure maintaining system to slowly increase the pressure to 22Mpa, carrying out 1-time nuclear magnetic resonance scanning on a low-field nuclear magnetic resonance analyzer 6 to obtain an initial oil-water distribution image, continuing to perform imbibition and stewing for 15 hours, and scanning the image of the rock core every 1 hour in the imbibition and replacement process of the stifled well to respectively obtain oil-water distribution images in the imbibition and replacement process (as shown in figures 3-5); in the core choke process, the pressure of the blind well at different time (shown in table 2) can be read through the displacement liquid pressure gauge 19, and then the change rule of the time and the pressure in the core choke process is obtained (shown in figure 2). Obtaining T at different times in the process of stuffy core through nuclear magnetic scanning2Relaxation time patterns, T obtained over time with scan2The relaxation time difference is a relative value that characterizes the oil content (FIG. 6). Through T2The oil displacement rate was determined from the relative values of the peak areas of the relaxation times (Table 3).
And S6, opening the liquid inlet valve 15 of the core holder 10 to naturally release pressure after the well closing is finished.
TABLE 1 base parameters of imbibition cores
| Reservoir characterization | Density g/mL | Diameter/mm | Height/mm | Porosity/%) | permeability/mD | Dry weight/g |
| Ultra-low permeability | 2.3 | 24.88 | 76.53 | 12.040 | 2.002 | 86.38 |
TABLE 2 variation of stuffy core pressure over time during imbibition displacement
TABLE 3 variation of stuffy core pressure over time during imbibition displacement
Although the present invention has been described with reference to the preferred embodiments, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (10)
1. The utility model provides a compact oil imbibition replacement's simulation experiment device based on nuclear magnetic resonance which characterized in that: the system comprises a ring pressure maintaining system, a heating system, a rock core clamping system, a low-field nuclear magnetic resonance analyzer, a displacement system and a liquid receiving system, wherein the rock core clamping system is arranged in the low-field nuclear magnetic resonance analyzer and comprises a rock core holder and a pressurizing circulation cavity, the pressurizing circulation cavity is sleeved at the rock core of the rock core holder, the input end and the output end of the heating system are respectively connected with an input pipe and an output pipe of the pressurizing circulation cavity, the output end of the displacement system is connected with a fluid injection pipe of the rock core clamping system, a fluid recovery pipe of the rock core clamping system is connected with the liquid receiving system, and the ring pressure maintaining system provides ring pressure for the rock core of the rock core holder.
2. The experimental device for simulating the tight oil imbibition and replacement based on the nuclear magnetic resonance as claimed in claim 1, wherein: the displacement system comprises a liquid supplementing container, a constant-pressure constant-speed pump and an intermediate container which are sequentially connected, the intermediate container is connected with a fluid injection pipe of the core clamping system through a liquid inlet valve, and a fluid recovery pipe of the core clamping system is connected with the liquid receiving system through a liquid outlet valve.
3. The experimental device for simulating the tight oil imbibition and displacement based on nuclear magnetic resonance as claimed in claim 1 or 2, wherein: the low-field nuclear magnetic resonance analyzer comprises a control box and a computer, and the rock core holder is placed in a magnetic field generated by the low-field nuclear magnetic resonance analyzer.
4. The experimental device for simulating the tight oil imbibition and replacement based on the nuclear magnetic resonance as claimed in claim 2, wherein: the ring pressure maintaining system comprises two sensors, an air source, a ring pressure tracking pump and a pressure display meter, wherein the two sensors can respectively read the fluid injection pressure of the rock core holder and the pressure of the fluid flowing out of the rock core holder, and the ring pressure tracking pump is respectively connected with a pipeline of the heating system and an input pipe of the pressurizing circulation cavity.
5. The experimental device for simulating the tight oil imbibition and displacement based on nuclear magnetic resonance as claimed in claim 1 or 2, wherein: the heating device comprises a circulating pump and two heating devices, and emptying valves are respectively arranged on pipelines at two sides of the two heating devices.
6. A compact oil imbibition displacement simulation test method based on nuclear magnetic resonance is characterized in that:
s1, establishing an oil displacement rate of the pretreated rock core by using nuclear magnetic crude oil or diesel oil, forming a seam in a manual seam-splitting mode, closing the rock core after seam formation, wrapping the rock core by using tinfoil paper, and opening two ends of the rock core;
s2, placing the core in a core clamping system of the compact oil imbibition replacement simulation test device based on nuclear magnetic resonance as claimed in any one of claims 1 to 4, and during experiment, opening a liquid inlet valve of the core clamping system and closing a liquid outlet valve of the core clamping system;
s3, adding a imbibition liquid containing a manganese chloride solution as a displacement liquid into the imbibition liquid container for pressurization, wherein the heating system adopts fluorinated oil as a circulating medium;
s4, opening the low-field nuclear magnetic resonance analyzer, opening the heating system to enable the temperature to reach the simulated formation temperature, starting a constant flow pump of the displacement system, and stopping and closing the liquid inlet valve after the imbibition liquid is pressurized to the well closing pressure for simulating imbibition displacement;
s5, starting a ring pressure tracking system to slowly increase the confining pressure to be higher than the pressurizing pressure of the imbibition liquid, and scanning a rock core by adopting nuclear magnetism at intervals to obtain an oil-water distribution image in the imbibition displacement process;
and S6, after the well is closed, opening a liquid outlet valve to naturally release pressure until no liquid enters the metering system, and ending the experiment.
7. The compact oil imbibition displacement simulation test method based on nuclear magnetic resonance as claimed in claim 5, wherein: the nuclear magnetic resonance device is used for simulating that the temperature of the stratum is between 60 and 120 ℃, the pressure pumping flow of a constant-pressure constant-flow pump in the displacement system is controlled to be between 0.1ml/min and 0.5ml/min, the pressure difference for simulating imbibition displacement is between 5MPa and 20MPa, the pressure pumping is stopped and the liquid inlet valve is closed after the imbibition displacement pressure is reached, the confining pressure is slowly increased to be 2 to 5MPa higher than the imbibition liquid pressure by the ring pressure tracking system, and the concentration range of the manganese chloride of the imbibition liquid is between 2.5 and 5.0 percent.
8. The compact oil imbibition displacement simulation test method based on nuclear magnetic resonance as claimed in claim 5, wherein: and controlling the time for soaking and smoldering the core to be between 10 and 30 hours, and longitudinally scanning the core every 1 hour in the process of soaking and replacing.
9. The compact oil imbibition displacement simulation test method based on nuclear magnetic resonance as claimed in claim 5, wherein: the pressure of different times is read through the displacement front-stage pressure gauge in the stuffy core process, the change rule of the time and the pressure in the stuffy core process is further obtained, and the recovery ratio of imbibition displacement of the stuffy core after different times is calculated according to the initial oil displacement rate.
10. The nuclear magnetic resonance-based compact oil imbibition displacement simulation test method of claim 9, wherein: passing through T after obtaining the change rule of time and pressure in the process of stuffy core2And determining the oil displacement rate at different times according to the peak area of the relaxation time graph.
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| CN115078222A (en) * | 2022-07-07 | 2022-09-20 | 西安石油大学 | Imbibition physical simulation experiment device and method considering seam end pressure difference |
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