Non-intrusive visual rock core model manufacturing method and displacement simulation system and method

Abstract

The invention provides a non-intrusive visual rock core model manufacturing method and a displacement simulation system and method, and belongs to the field of oil and gas field development physical simulation. The manufacturing method comprises the steps that the type of rock skeleton particles and the type of clay mineral particles are determined; the wrapping shell is filled with rock skeleton particles, and an uncemented rock core model built by a rock skeleton is formed after pressurization; preparing chromium acetate and a temperature-resistant polymer into a first cementing solution; injecting a first cementing solution into the uncemented rock core model, and curing to form an incompletely cemented rock core model; preparing clay mineral particles and a NaHCO3 solution to form a second cementing solution; and injecting a second cementing solution into the incompletely cemented rock core model, and curing to form a completely cemented rock core model. According to the method provided by the invention, the non-intervention visual rock core model can be obtained, and the method of detaching, cutting and the like does not need to intervene into the end surface of the experimental rock core in a displacement simulation experiment, so that the real-time visual monitoring of the displacement process is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of physical simulation of oil and gas field development, and in particular to a non-intrusive visual core model, a method for making the non-intrusive visual core model, a displacement simulation experimental system and a displacement simulation experimental method. Background Art

[0002] As a common reservoir simulation object, core has long been used in physical simulation experiments for oil and gas field development. During the displacement process, core has certain temperature and pressure resistance properties, so that the temperature and pressure conditions of the development experiment can be consistent with the actual reservoir.

[0003] Common core models are mainly divided into three types: natural cores, artificial cores and Bailey cores. The mineral composition of natural cores is relatively complex, and because the pore structures of natural cores are quite different, it is difficult to conduct repeated experiments to verify the influence of a certain component in the core on the results of displacement experiments. Bailey cores are closest to natural cores in terms of core physical properties such as pore structure, but different types of clay minerals cannot be effectively filled inside them, and there are deficiencies in studying the influence of reservoir composition on displacement experimental results. Artificial cores are one of the most common experimental cores. Conventional artificial cores are mainly composed of quartz sand and organic binders. Fixed artificial cores are formed by setting specific temperatures and shaping and compacting. However, the degree of cementation of this type of core is high and it cannot be washed away by the injected fluid to migrate. At the same time, the temperature resistance of the cement in the core is poor. When simulating thermal oil recovery experiments, organic binders will have an adverse effect on the experiment.

[0004] For example, a Chinese patent document with a publication date of March 8, 2019 and a publication number of CN109443886A provides a method for making a simulated core with a fixed pore throat and particle surface. The method uses a clay suspension and a fixed-size glass ball to make a core model with a specific pore throat size and clay minerals attached to the pore throat surface. This method can achieve different properties of the particle surface to a certain extent, and can quantitatively control the mass ratio of clay minerals and minerals such as quartz. However, this method has major problems in simulating the composition of the rock skeleton and fixing the structure of the rock sample, and factors such as sand production will have a greater impact on the displacement results. Summary of the invention

[0005] In view of the technical problem that a core model close to the pore structure of the oil reservoir cannot be formed in the prior art, the present invention provides a method for making a non-intrusive visualized core model. The method can form a non-intrusive visualized core model. The core model can be inserted into the end face of the experimental core in the displacement simulation experiment without the need for disassembly and cutting, thereby realizing real-time visualized monitoring of the displacement process.

[0006] In addition, the present invention also provides a displacement simulation experimental method, which can intuitively test the oil and water distribution inside the core model during the displacement process with the help of nuclear magnetic resonance technology, and can analyze the influence of different clay minerals on the macroscopic displacement effect and microscopic oil and water distribution.

[0007] To achieve the above-mentioned purpose, the first aspect of the present invention provides a method for making a non-invasive visual core model, which comprises the following steps: determining the type of rock skeleton particles and the type of clay mineral particles according to the simulated stratum; filling the rock skeleton particles in the encapsulating shell, and forming an uncemented core model constructed by the rock skeleton after pressurization and heating treatment; preparing chromium acetate and a heat-resistant polymer in a preset ratio to form a first cementing solution; the temperature-resistant range of the heat-resistant polymer is above 90°C; injecting the first cementing solution into the uncemented core model, and solidifying it according to a preset displacement confining pressure and a preset displacement cycle to form an incompletely cemented core model; preparing clay mineral particles and NaHCO3 solution to form a second cementing solution; injecting the second cementing solution into the incompletely cemented core model, and solidifying it according to a preset displacement confining pressure and a preset displacement cycle to form a completely cemented core model.

[0008] In an exemplary embodiment of the present invention, the rock skeleton particles may be at least one of quartz sand and feldspar; the clay mineral particles may be at least one of montmorillonite, kaolinite, illite and chlorite.

[0009] In an exemplary embodiment of the present invention, the packaging shell may be made of a transmissive material or a semi-transmissive material.

[0010] In an exemplary embodiment of the present invention, the encapsulating shell may be a polyetheretherketone shell.

[0011] In an exemplary embodiment of the present invention, the temperature-resistant polymer may be polyacrylamide having a temperature resistance of above 90°C.

[0012] In an exemplary embodiment of the present invention, the preparation of clay mineral particles and NaHCO3 solution to form a second binder solution may include: adding clay mineral particles to NaHCO3 solution and continuously stirring to form a binder suspension; vibrating the binder suspension and adding NaOH powder until the pH value of the upper suspension in the binder suspension is greater than 8, thereby obtaining a second binder solution.

[0013] In an exemplary embodiment of the present invention, the manufacturing method may further include: drying the incompletely cemented core model and / or the completely cemented core model.

[0014] A second aspect of the present invention provides a non-intrusive visualized core model, wherein the core model is manufactured according to the above-mentioned method for manufacturing a non-intrusive visualized core model.

[0015] The third aspect of the present invention provides a displacement simulation experiment system for performing displacement simulation experiments on the above-mentioned core model, and the displacement simulation experiment system includes: a displacement power device, a nuclear magnetic resonance scanning device and a data acquisition device; the displacement power device is used to inject steam and various fluids into the core model to simulate the development process of the oil reservoir in the multi-component composite drive; the nuclear magnetic resonance scanning device is used to obtain the oil and water distribution identification results inside the non-intrusive visual core model during the displacement process; the data acquisition device is used to collect displacement data, and the displacement data includes pressure, temperature and production measurement.

[0016] The fourth aspect of the present invention provides a displacement simulation experimental method, which is applied to the above-mentioned displacement simulation experimental system. The displacement simulation experimental method includes: connecting a non-intrusive visual core model to a displacement power device to test the basic physical properties of the core, wherein the basic physical properties of the core include the porosity, permeability and initial water saturation of the core model; injecting different fluids into the non-intrusive visual core model to simulate the development process of the oil reservoir in the multi-component composite drive, and during the displacement process, using a nuclear magnetic resonance scanning device to obtain the oil and water distribution identification results inside the non-intrusive visual core model; based on the oil and water distribution identification results, analyzing the displacement effects of different fluids on different pore fillings.

[0017] Through the technical solution provided by the present invention, the present invention has at least the following technical effects:

[0018] (1) The present invention provides a method for making a core model close to the pore structure of an oil reservoir. The method is safe, reliable, and easy to operate. In addition, during the making process, the physical and chemical comprehensive adsorption of the suspension of various inorganic minerals on the surface of the rock skeleton is taken into consideration, thereby strengthening the core pore structure and reducing the influence of chemical and high temperature on the core pore structure.

[0019] (2) The core model obtained by the present invention is a non-intrusive visual core model, which can be used in displacement simulation experiments without the need to intervene in the end face of the experimental core by disassembly and cutting methods, thereby achieving real-time visual monitoring of the displacement process;

[0020] (3) The displacement simulation experimental system and method provided by the present invention can study the influence of multi-fluid displacement on one or more clay minerals, and can continuously perform nuclear magnetic resonance testing during the displacement process to intuitively reflect the oil-water distribution and obtain the microscopic mechanism of multi-thermal fluid composite flooding on clay mineral-containing cores.

[0021] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings are used to provide a further understanding of the embodiments of the present invention and constitute a part of the specification. Together with the following specific implementations, they are used to explain the embodiments of the present invention, but do not constitute a limitation on the embodiments of the present invention. In the accompanying drawings:

[0023] Figure 1 A flow chart of a method for making a non-intrusive visual core model provided by the first embodiment of the present invention;

[0024] Figure 2 A schematic cross-sectional structure diagram of a non-intrusive visualized core model provided by the first embodiment of the present invention;

[0025] Figure 3 A schematic diagram of the structure of a displacement simulation experimental system provided by the second embodiment of the present invention;

[0026] Figure 4 A flow chart of a displacement simulation experimental method provided for a second embodiment of the present invention;

[0027] Figure 5 A T2 spectrum for calculating the recovery factor provided by the third embodiment of the present invention;

[0028] Figure 6 A core nuclear magnetic resonance imaging image of an initial state provided by the fourth embodiment of the present invention;

[0029] Figure 7 This is a nuclear magnetic resonance imaging image of a core at the end of displacement provided by the fourth embodiment of the present invention.

[0030] Description of Reference Numerals

[0031] 1- non-intrusive visual core model; 2- computer; 11- top surface mold cover; 12- top surface sand control net; 13- sand filling pipe part; 14- bottom surface sand control net; 15- bottom surface mold cover; 16- transmissive wrapping shell; 21- high-precision double-cylinder displacement plunger pump; 22- steam generator; 23- oil phase intermediate container; 24- water phase intermediate container; 25- electronic pressure gauge; 26- pressure relief measuring cylinder; 27- six-way valve; 31- core clamp; 32- online nuclear magnetic resonance scanner; 33- injection end electronic thermometer; 34- outlet end electronic thermometer; 41- back pressure valve; 42- measuring cylinder; 43- electronic balance; 44- high-precision single-cylinder back pressure plunger pump. DETAILED DESCRIPTION

[0032] The specific implementation of the embodiment of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the embodiment of the present invention, and is not used to limit the embodiment of the present invention.

[0033] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0034] In the present invention, unless otherwise specified, the directional words used, such as "upper, lower, top, bottom", are usually used to describe the relative positional relationship of the components in terms of the directions shown in the drawings or in terms of the vertical, perpendicular or gravity directions. "First", "second", etc. are only used for the convenience of description and distinction, and cannot be understood as indicating or implying relative importance.

[0035] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "installation", "connection", etc. should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integrated connection; it can be a direct connection, or an indirect connection; it can be a wired connection, or a wireless connection. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0036] Since the rock mineral types filled in conventional core models such as natural cores, Bailey cores and artificial cores are relatively single, the present invention considers manufacturing artificial cores based on the mineral composition of some oil reservoirs or research targets. The present invention adjusts the types and data of rock skeletons and clay minerals according to the simulated strata, and fills the rock skeletons and clay minerals into a transmissive coating shell, and obtains a non-intrusive visual core model close to the pore structure of the reservoir after solidification. During the displacement experiment, by placing the core in a displacement simulation experiment system with a nuclear magnetic resonance instrument, the presence of the transmissive coating shell can enable the core to continuously reflect the oil and water distribution in the displacement process with the help of nuclear magnetic resonance testing, thereby obtaining accurate reservoir permeability, porosity, free fluid, bound fluid and other related parameters, and at the same time, the microstructure in the rock pores and the oil distribution characteristics can be accurately analyzed.

[0037] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0038] Embodiment 1

[0039] The first embodiment of the present invention provides a method for making a non-invasive visual core model. Figure 1 , the method comprises the following steps:

[0040] Step S101: Determine the type of rock skeleton particles and the type of clay mineral particles according to the simulated stratum.

[0041] Here, different types and quantities of rock skeleton particles and clay mineral particles can be selected to prepare the core model together according to the mineral composition characteristics of the simulated strata. The material selected for the rock skeleton particles can be one or more of quartz sand and feldspar of different particle sizes, with a compressive strength of more than 4MPa and a temperature resistance of more than 400°C. The material selected for the clay mineral particles can be one or more of montmorillonite, kaolinite, illite and chlorite.

[0042] Step S102: rock skeleton particles are filled into the encapsulating shell, and after pressure treatment and heating treatment, an uncemented core model constructed by the rock skeleton is formed.

[0043] Exemplarily, the process of making an uncemented core model constructed from a rock skeleton may include but is not limited to the following sub-steps S1021 to S1024.

[0044] Sub-step S1021: After fixing the leak-proof screen and the bottom mold cover at the bottom of the wrapping shell, fill sand into the wrapping shell. When the sand filling height is slightly higher than the transmissive wrapping shell, fix a 1200-mesh sand-proof net on the top surface of the mold, then open the mold cover on the bottom surface of the mold, and apply an axial pressure of 6MPa on the outside of the sand-proof net on the top and bottom surfaces of the mold.

[0045] It should be noted that the sand filling here refers to filling the rock skeleton particles.

[0046] Sub-step S1022: After the axial stress value stabilizes, the axial stress is increased by 1 MPa every 2 hours. If the rock particles are completely pressed into the mold, the sand-proof net is disassembled after the pressure is released to fill a small amount of rock particles into the end face. After completion, the sand-proof net is re-fixed and the pressure is re-applied from 6 MPa.

[0047] Sub-step S1023: When the pressure increases to 12 MPa and the rock particles are stably slightly higher than the transmissive encapsulation shell, the top and bottom surfaces are covered with molds respectively.

[0048] This pressurization method is to promote the mutual fit of particles in the core through mechanical compaction and improve its structural stability.

[0049] Sub-step S1024: placing the pressurized core wrapped by the encapsulation shell in a constant temperature box at 100° C. for 24 hours to form an uncemented core model constructed by a rock skeleton.

[0050] Step S103: preparing chromium acetate and a temperature-resistant polymer according to a first preset ratio to form a first bonding solution.

[0051] Here, the temperature-resistant polymer has a temperature range of above 90° C. For example, the temperature-resistant polymer may be a temperature-resistant polyacrylamide having a temperature resistance of above 90° C. The temperature-resistant polyacrylamide is a copolymer with acrylamide as the main link but with a ring structure, a strong hydrophilic group, and an associable hydrocarbon chain.

[0052] Step S104: injecting the first cementing solution into the uncemented core model, and solidifying the solution according to a preset displacement confining pressure and a preset displacement period to form an incompletely cemented core model.

[0053] Here, the preset displacement confining pressure can be set to 3 MPa, and the preset displacement period can be set to more than 10 PV, so as to achieve effective consolidation under low pressure conditions. The first cementing solution functions to solidify the rock particle skeleton.

[0054] Furthermore, in this step, the incompletely cemented core model can be placed in a dryer and heated at 80° C. to 90° C. for more than 4 hours to solidify the first cementing solution on the rock surface and consolidate the rock structure.

[0055] Step S105: preparing clay mineral particles and NaHCO3 solution to form a second cementing solution.

[0056] Illustratively, the process of preparing the clay mineral particles and the NaHCO 3 solution to form the second cementing solution includes but is not limited to the following sub-steps S1051 to S1053.

[0057] Sub-step S1051: Mix the inorganic binder in a container according to a second preset ratio and stir thoroughly to form binder powder.

[0058] Among them, inorganic cements mainly include clay mineral particles such as montmorillonite, illite and kaolinite.

[0059] Sub-step S1052: gradually add the binder powder into the NaHCO3 solution, heat the mixed solution and stir it continuously during this process so that the binder powder can be fully dispersed in the solution, and use an ultrasonic stirrer to treat the mixed solution to obtain a relatively stable binder suspension.

[0060] Sub-step S1053: Place the cement suspension in a cleaning machine and vibrate the cement suspension with 30 Hz sound waves. During this process, add a small amount of NaOH powder to adjust the pH value. Take the upper layer of the suspension to measure the pH value. When the pH value reaches above 8, the suspension can be made into a second cement solution.

[0061] Here, the reason for adding NaOH powder to adjust the pH value is to increase the pH value of the solution as quickly as possible. If NaHCO3 solution is added, a large amount of NaHCO3 solution is required to make the pH reach above 8, which makes the water component content in the solution too high.

[0062] Step S106: injecting the second cementing solution into the incompletely cemented core model, and solidifying it according to a preset displacement confining pressure and a preset displacement cycle to form a completely cemented core model.

[0063] The function of the second cementing solution is to adhere clay mineral particles to the surface of the rock skeleton.

[0064] For example, the second cementing solution can be loaded into an intermediate container, and the second cementing solution can be injected into the incompletely cemented core model using a displacement device. The displacement confining pressure is set to 3 MPa, and the displacement cycle exceeds 10 PVs to achieve effective consolidation under medium and high pressure conditions to form a completely cemented core model.

[0065] Furthermore, in this step, the fully cemented core model can be placed in a dryer and heated at 100°C to 120°C for more than 4 hours to allow the clay minerals to adhere to the surface of the rock skeleton, thereby completing the core making process and obtaining a non-intrusive visual core model.

[0066] In this embodiment, the encapsulation shell is made of a transmissive material or a semi-transmissive material, has good plasticity, ray semi-transmissivity and good mechanical properties, can realize the visualization of the core model, and can be inserted into the end face of the experimental core during the displacement process without using methods such as disassembly and cutting. For example, the encapsulation shell can be a polyetheretherketone shell, which is semi-transmissive and does not need to be disassembled for scanning during the displacement process, and can realize real-time visual monitoring during the displacement process.

[0067] The non-intrusive visualized core model of this embodiment can be obtained by the above-mentioned production method. Please refer to Figure 2 The non-intrusive visualized core model consists of a top mold cover 11, a top sand-proof net 12, a sand-filling pipe part 13, a sand-proof net 14, a bottom mold cover 15 and a transmissive wrapping shell 16. The sand-filling pipe part 13 is arranged in the transmissive wrapping shell 16 to fill rock skeleton particles and inorganic cement. The bottom surface of the transmissive wrapping shell 16 is fixed with a bottom sand-proof net 14 and a bottom mold cover 15, and the top surface of the transmissive wrapping shell 16 is fixed with a top sand-proof net 12 and a top mold cover 11 to prevent rock solid particles from leaking from the bottom and top.

[0068] Embodiment 2

[0069] The second embodiment of the present invention provides a displacement simulation experiment system, which mainly includes: a displacement power device, a nuclear magnetic scanning device and a data acquisition device. Among them, the displacement power device is used to inject steam and various fluids into the core model to simulate the reservoir formation and displacement process; the nuclear magnetic scanning device is used to obtain the oil and water distribution identification results inside the non-intrusive visual core model during the displacement process; the data acquisition device is used to collect displacement data, and the displacement data includes pressure, temperature and production measurement.

[0070] like Figure 3 As shown, the displacement power device includes a high-precision double-cylinder displacement plunger pump 21, a steam generator 22, an oil phase intermediate container 23, a water phase intermediate container 24, a pressure relief measuring cylinder 26, a six-way valve 27, a core holder 31, a back pressure valve 41 and a high-precision single-cylinder back pressure plunger pump 44. The nuclear magnetic scanning device includes an online nuclear magnetic scanner 32. The data acquisition device includes an electronic pressure gauge 25, an injection end electronic thermometer 33, an outlet end electronic thermometer 34, a measuring cylinder 42 and an electronic balance 43.

[0071] The core holder 31 is used to place the non-intrusive visualized core model 1, and the online nuclear magnetic resonance scanner 32 is placed on the core holder 31 to test the internal oil and water distribution of the non-intrusive visualized core model. The steam generator 22 is connected to the core holder 31 through a fluid pipeline and a six-way valve 27 to inject steam into the core model.

[0072] The high-precision double-cylinder displacement plunger pump 21 is connected to the oil phase intermediate container 23 and the water phase intermediate container 24 respectively, and is used to provide the oil phase and the water phase conveying power. The oil phase intermediate container 23 and the water phase intermediate container 24 are connected to the core holder 31 through the fluid pipeline and the six-way valve 27, and are used to inject oil and water into the core model.

[0073] The high-precision single-cylinder back-pressure plunger pump 44 is connected to the core holder 31 through a fluid pipeline and a back-pressure valve 41, and is used to apply pressure to the core model. The high-precision single-cylinder back-pressure plunger pump 44 is a back-pressure pump, which provides pressure to the back-pressure valve 41 to ensure that sufficient pressure is accumulated to allow the sand filling pipe to produce fluid.

[0074] The pressure relief cylinder 26 is connected to the six-way valve 27. When the system is over-pressured, the vent switch on the six-way valve can be opened and connected to the pressure relief cylinder 26 to ensure safety during the experiment. Specifically, the pressure relief cylinder can be placed on an electronic weighing meter, and the weight change of the pressure relief cylinder can be measured by the electronic weighing meter.

[0075] The measuring cylinder 42 is placed on an electronic balance 43, and the measuring cylinder 42 is connected to the back pressure valve 41. The electronic balance 43 can measure the weight change of the measuring cylinder, and the measuring cylinder 42 is used to monitor the output.

[0076] The electronic pressure gauge 25 is connected to the six-way valve 27 to monitor the pressure change in the six-way valve. The injection end electronic thermometer 33 and the outlet end electronic thermometer 34 are respectively arranged on both sides of the core holder 31 to monitor the temperature change of the injection end and the outlet end.

[0077] Data acquisition devices such as the electronic pressure gauge 25, the injection end electronic thermometer 33, and the outlet end electronic thermometer 34 are also connected to the computer 2 to collect displacement data and realize dynamic statistics and transmission of displacement data.

[0078] The second embodiment of the present invention also provides a displacement simulation experimental method, please refer to Figure 4 , the experimental method comprises the following steps:

[0079] Step S201: Connect the non-intrusive visualized core model to the displacement power device to test the porosity, permeability and initial water saturation of the core model.

[0080] For example, the porosity of the core model can be calculated by using the vacuum saturated water volume or the filled water volume, wherein the filling method includes the dry filling method and the wet filling method. Specifically, when the dry filling method is used to fill the sand filling pipe part, the porosity of the non-intrusive visualized core model can be calculated by using the vacuum saturated water method, and when the wet filling method is used to fill the sand filling pipe, the porosity of the non-intrusive visualized core model can be calculated by using the filled water volume.

[0081] The calculation formula for porosity is: Among them, V w It is the volume of vacuum saturated water in dry filling method or the volume of water filled in wet filling method; d is the inner radius of the sand filling pipe; h is the length of the sand filling pipe.

[0082] Formation water can be injected into the sand filling pipe part to perform saturated water operation, and the permeability of the core model is calculated according to the injection amount of formation water in the saturated water operation and the pressure difference between the injection end and the outlet end. Specifically, formation water for saturated water operation can be stored in an intermediate displacement container (e.g., a water phase intermediate container), the displacement pump (e.g., a high-precision double-cylinder displacement plunger pump) and the back pressure pump (e.g., a high-precision single-cylinder back pressure plunger pump) are turned on and the parameters are adjusted, the valve of the multi-way valve of the intermediate displacement container is opened, and formation water is injected into the sand filling pipe part at a constant flow rate to perform saturated water operation, and the saturated water volume in the saturated water operation is recorded. After the saturated water operation is completed, wait for the pressure and water production to stabilize, record the pressure difference between the injection end and the outlet end of the sand filling pipe, and calculate the permeability using the Darcy formula.

[0083] The formula for calculating the permeability is: Where k is the permeability, Q is the injection volume, μ W is the viscosity of formation water, L is the length of the sand filling pipe, A is the end surface area of ​​the sand filling pipe, and ΔP is the pressure difference between the injection end and the outlet end of the sand filling pipe.

[0084] Crude oil may be injected into the sand filling pipe part to perform an oil saturation operation. Specifically, crude oil for oil saturation operation may be stored in an intermediate displacement container (e.g., an oil phase intermediate container), and the displacement pump may be controlled to inject crude oil into the sand filling pipe part at a constant flow rate until no formation water flows out of the outlet end to perform a water saturation operation, and the volume of produced water in the oil saturation operation is recorded. The initial water saturation of the core model is calculated based on the saturated water volume in the water saturation operation and the produced water volume in the oil saturation operation.

[0085] The calculation formula for initial water saturation is: Among them, S wi is the initial water saturation, V wi is the saturated water volume in saturated water operation, V wo is the volume of produced water in saturated oil operation.

[0086] By calculating the porosity, permeability and initial water saturation of the core model, it can be used to evaluate the manufactured core model and also to calculate various displacement experiment parameters.

[0087] Step S202: Inject different fluids into the non-intrusive visual core model to simulate the oil and gas reservoir development process, and record the pressure, temperature and production.

[0088] For example, after the displacement simulation experiment system is assembled, saturated water, saturated oil and other component composite flooding can be carried out successively. Specifically, after the saturated oil operation is completed, the temperature of the thermostat can be set to the reservoir temperature, and the reservoir temperature allows the sand filling pipe part after saturated oil to age for 72h to 144h to give the crude oil and ideal rock particles sufficient contact time, and different types of oil displacement agents are loaded in the intermediate displacement container, and steam and / or gas can be superimposed on the oil displacement agent as a displacement medium for displacement experiments.

[0089] The water phase component in the displacement fluid contains manganese chloride with a mass fraction of 20%. Manganese chloride as a water phase base fluid can shield the signal of water, thereby realizing the oil-water distribution separation of the nuclear magnetic resonance image.

[0090] Step S203: After the simulation development process is completed, the oil and water distribution inside the core model is observed by nuclear magnetic resonance.

[0091] For example, a nuclear magnetic resonance scanning device can be used to take the core image obtained at the end of oil saturation as the starting point. During the displacement process, different injection volume multiples are selected to collect T2 spectrum and other data, and the rock phase, water phase and oil phase are separated and identified using software.

[0092] NMR T2 spectroscopy (eg Figure 5 The envelope area collected by the above method can reflect the total hydrogen content characteristics at different displacement nodes. At the same time, by comparing the areas of the T2 spectrum envelopes at different injection volume multiples, the recovery factor at different times can be calculated using the following formula:

[0093]

[0094] Where R is the recovery factor; S0 is the area enclosed by the envelope of the nuclear magnetic resonance T2 spectrum peak after the core is saturated with oil; S i It is the area enclosed by the envelope of the nuclear magnetic resonance T2 spectrum peak at different injection multiples.

[0095] It should be noted that the distribution image of simulated oil in the core pores during the displacement process formed by nuclear magnetic resonance imaging technology can characterize the strength of the hydrogen signal. The higher the pixel brightness of the distribution image, the stronger the hydrogen signal, that is, the higher the oil content; conversely, the lighter the pixel brightness in the distribution image, the weaker the hydrogen signal.

[0096] Step S204: analyzing the influence of different fluids on different types of clay minerals based on the nuclear magnetic resonance results.

[0097] For example, by adjusting the type and amount of clay minerals, the influence of specific clay minerals on the macroscopic displacement effect can be obtained; on this basis, nuclear magnetic resonance is used to analyze the oil-water distribution after displacement, and the influence of different fluids on the displacement effect of specific pore fillings can be obtained to obtain the influence of specific clay minerals on the microscopic oil-water distribution.

[0098] By controlling the types of steam and displacement agents, the adaptability of different clay minerals to multi-component fluids and high temperatures can be evaluated; on this basis, nuclear magnetic resonance is used to analyze the oil-water distribution after displacement, the influence of different fluids on the displacement effects of different pore fillings, and the microscopic mechanism of multi-component thermal fluid composite flooding on clay mineral-containing cores is obtained, which will promote the development of physical simulation experiments on oil and gas layers with cores as research objects.

[0099] Embodiment 3

[0100] A third embodiment of the present invention provides a method for making an artificial core model, the method comprising the following steps:

[0101] Step S301: Determine the type of rock skeleton particles and the type of clay mineral particles.

[0102] Specifically, 1250 mesh montmorillonite was selected as the only type of clay mineral for filling, and 20 mesh and 40 mesh quartz were selected as rock skeleton particles for filling.

[0103] Step S302: Filling rock skeleton particles to form an uncemented core model constructed by the rock skeleton.

[0104] Specifically, after the bottom surface of the transmissive shell is sealed with a sand-proof net, 200g of quartz sand particles are weighed and placed in the transmissive shell, and axial pressure is applied for compaction. The pressure treatment starts at 6MPa and increases by 1MPa every 2h until the axial pressure reaches 12MPa, so that the rock particles of the transmissive shell are fully compacted. Then, the core wrapped by the transmissive shell after pressurization is placed in a 100°C thermostat and heated for 24h to form an uncemented core model built by a rock skeleton.

[0105] Step S303: Chromium acetate and a temperature-resistant polymer are selected to prepare a bonding chemical solution A (ie, a first bonding solution).

[0106] Step S304: inject the cementing chemical solution A into the uncemented core model by using the displacement device to implement effective consolidation under low pressure conditions to form an incompletely cemented core model. The displacement confining pressure is set to 3 MPa, and the displacement cycle exceeds 10 PV.

[0107] Step S305: selecting clay minerals to prepare a cementing chemical solution B (ie, a second cementing solution).

[0108] Specifically, 80 g of montmorillonite particles were weighed and gradually poured into 800 mL of distilled water and stirred thoroughly, and NaHCO3 powder was stirred in to form a clay mineral suspension. The clay mineral suspension was then placed in a cleaning machine, and the mixed suspension was vibrated with 30 Hz sound waves. During this process, a small amount of NaOH powder was added, and the upper suspension in the suspension was taken to measure the pH value. When the pH value reached 8, the suspension could be made into a cementing chemical solution B.

[0109] Step S306: Use the displacement device to inject the cementing chemical solution B into the incompletely cemented core model to implement effective consolidation under medium and high pressure conditions to form a completely cemented core model. The displacement confining pressure is set to 3Mpa, and the displacement cycle exceeds 10 PV.

[0110] Step S307: The fully cemented core model is placed in a constant temperature box and heated at 100° C. for 24 hours to allow clay minerals to adhere to the surface of the rock skeleton, completing the core making process and obtaining a non-intrusive visual core model.

[0111] The core model is a regular cylinder with a bottom radius of 2.5 cm and a height of 5 cm.

[0112] The third embodiment of the present invention further provides a displacement simulation experimental method, which comprises the following steps:

[0113] Step S'301: Place the obtained non-intrusive visualized core model into a core holder, select a water-soluble viscosity reducer solution + steam as a displacement agent, connect various parts of the displacement simulation experimental system and test the air tightness of the device.

[0114] Step S'302: Testing the porosity, permeability and initial water saturation of the core model.

[0115] (1) The saturated water process was carried out with an injection flow rate of 0.5 mL / min. After the pressure and water production were stabilized, the pressure difference was recorded as 0.0017 × 10 -1 MPa, and the permeability is calculated using Darcy's formula to be 1248mD.

[0116] (2) Take out the core model and use the mass difference before and after saturation with water (27.48 g) to calculate the porosity to be 0.28.

[0117] (3) After saturation with water, the oil saturation process was carried out at an injection rate of 0.25 mL / min. The core model was then placed in a constant temperature box at the formation temperature for 144 h to simulate the reservoir aging process. The difference in mass between produced water and saturated water was 23.08 g, and the initial water saturation was calculated to be 16%.

[0118] Step S'303: Inject fluid into the core model to simulate the oil and gas reservoir development process, and record the pressure, temperature and production.

[0119] Specifically, steam was injected at an injection rate of 0.2 mL / min, and a water-soluble viscosity reducer solution was injected at an injection rate of 0.1 mL / min to simulate the reservoir development process. When the water content reached 95%, the high-precision dual-cylinder displacement plunger pump was turned off to stop fluid injection, and the pressure, temperature and production change data during the process were recorded. When the temperature dropped to room temperature, the vent valve of the six-way valve was opened to relieve pressure.

[0120] Step S'304: After the simulation development process is completed, the oil and water distribution inside the core model is observed using nuclear magnetic resonance, and the effects of different fluids on different types of clay minerals are analyzed based on the nuclear magnetic resonance results.

[0121] Specifically, after the pressure and temperature return to normal levels, the core model with the transmissive coating shell is taken out and the displacement process is completed. By analyzing the NMR test results during the displacement process, the oil and water distribution is observed, and the impact of the high-temperature viscosity reducer solution on the development of the rock model with a high montmorillonite content is analyzed. Figure 6 and Figure 7 As shown in the figure, it can be found that the pixel brightness of the image decreases significantly after displacement, and the oil saturation in the entire core model decreases significantly.

[0122] Embodiment 4

[0123] A fourth embodiment of the present invention provides a method for making an artificial core model, the method comprising the following steps:

[0124] Step S401: Determine the type of rock skeleton particles and the type of clay mineral particles.

[0125] Specifically, 1250 mesh montmorillonite and kaolinite were selected as the filling clay mineral types, and 20 mesh and 40 mesh quartz and 40 mesh feldspar were selected as the filling rock skeleton particles.

[0126] Step S402: Filling rock skeleton particles to form an uncemented core model constructed by the rock skeleton.

[0127] Specifically, after the bottom surface of the transmissive shell is sealed with a sand-proof net, 100g of quartz sand and feldspar particles are weighed and placed in the transmissive shell, and axial pressure is applied for compaction. The pressure treatment starts at 6MPa and increases by 1MPa every 2h until the axial pressure reaches 12MPa, so that the rock particles of the transmissive shell are fully compacted. Then, the core wrapped by the transmissive shell after pressurization is placed in a 100℃ thermostat and heated for 24h to form an uncemented core model built by a rock skeleton.

[0128] Step S403: Chromium acetate and a temperature-resistant polymer are selected to prepare a bonding chemical solution A (ie, a first bonding solution).

[0129] Step S404: inject the cementing chemical solution A into the uncemented core model by using the displacement device to implement effective consolidation under low pressure conditions to form an incompletely cemented core model. The displacement confining pressure is set to 3Mpa, and the displacement cycle exceeds 10 PV.

[0130] Step S305: selecting clay minerals to prepare a cementing chemical solution B (ie, a second cementing solution).

[0131] Specifically, 40g of montmorillonite and kaolinite were weighed as clay mineral particles, and after the total mass of 80g of clay minerals was fully mixed, they were gradually poured into 800mL of distilled water and fully stirred, and NaHCO3 powder was stirred into it to form a clay mineral suspension. The clay mineral suspension was then placed in a cleaning machine, and the mixed suspension was vibrated with 30Hz sound waves. During this process, a small amount of NaOH powder was added, and the upper suspension in the suspension was taken to measure the pH value. When the pH value reached 10, the suspension could be made into a cementing chemical solution B.

[0132] Step S406: Use the displacement device to inject the cementing chemical solution B into the incompletely cemented core model to implement effective consolidation under medium and high pressure conditions to form a completely cemented core model. The displacement confining pressure is set to 3Mpa, and the displacement cycle exceeds 10 PV.

[0133] For example, the cementing chemical solution B can be gradually poured into the incompletely cemented core model, and the water can be continuously dried in a constant temperature box. When the mass of the evaporated rock reaches 240 g, the pouring of the clay mineral suspension is stopped.

[0134] Step S407: The fully cemented core model is placed in a constant temperature box and heated at 100° C. for 24 hours to allow clay minerals to adhere to the surface of the rock skeleton, completing the core making process and obtaining a non-intrusive visualized core model.

[0135] The core model is a regular cylinder with a bottom radius of 2.5 cm and a height of 5 cm.

[0136] The fourth embodiment of the present invention further provides a displacement simulation experimental method, which comprises the following steps:

[0137] Step S'401: Place the obtained non-intrusive visualized core model into a core holder, select carbon dioxide + steam + oil-soluble viscosity reducer as a displacement agent, connect various parts of the displacement simulation experimental system and test the air tightness of the device.

[0138] Step S'402: Testing the porosity, permeability and initial water saturation of the core model.

[0139] (1) The saturated water process was carried out with an injection flow rate of 0.5 mL / min. After the pressure and water production were stabilized, the pressure difference was recorded as 0.0013 × 10 -1 MPa, and the permeability calculated using Darcy's formula is 954mD.

[0140] (2) Take out the core model and use the mass difference before and after saturation with water to calculate the porosity to be 0.25.

[0141] (3) After saturation with water, the oil saturation process was carried out at an injection rate of 0.25 mL / min. The core model was then placed in a constant temperature box at the formation temperature for 144 h to simulate the reservoir aging process. The difference in mass between produced water and saturated water was 22.23 g, and the initial water saturation was calculated to be 12%.

[0142] Step S'403: Inject fluid into the core model to simulate the oil and gas reservoir development process, and record the pressure, temperature and production.

[0143] Specifically, the steam generator was turned on to inject steam at an injection rate of 0.1 mL / min, the gas flow controller was turned on to inject carbon dioxide gas at an injection rate of 0.1 mL / min, and the high-precision single-cylinder displacement plunger pump was turned on to inject oil-soluble viscosity reducer at an injection rate of 0.1 mL / min to simulate the reservoir development process until the water content reached 95%, and then the high-precision double-cylinder displacement plunger pump was turned off to stop fluid injection, and the pressure, temperature and production change data during the process were recorded. The thermostat was closed, and after the temperature dropped to room temperature, the vent valve of the six-way valve was opened to relieve pressure.

[0144] Step S'404: After the simulation development process is completed, the oil and water distribution inside the core model is observed using nuclear magnetic resonance, and the effects of different fluids on different types of clay minerals are analyzed based on the nuclear magnetic resonance results.

[0145] Specifically, after the pressure and temperature return to normal levels, the core model with the permeable shell is taken out and the displacement process is completed. By analyzing the nuclear magnetic resonance test results during the displacement process, the oil and water distribution is observed, and the impact of the composite flooding of hot gas (steam + carbon dioxide gas + oil-soluble viscosity reducer) on the development of rock models with high kaolinite and montmorillonite content is analyzed.

[0146] Embodiment 5

[0147] A fifth embodiment of the present invention provides a method for making an artificial core model, the method comprising the following steps:

[0148] Step S501: Determine the type of rock skeleton particles and the type of clay mineral particles.

[0149] The type and content of the filler are determined based on the core X-ray diffraction whole-rock mineral analysis report of the actual oil reservoir. The relevant parameters are shown in Table 1.

[0150] Table 1 X-ray diffraction analysis report of a real oil reservoir core

[0151]

[0152] Therefore, in this embodiment, various clay mineral particles with a particle size of 1250 mesh in Table 1 are selected, that is, montmorillonite, illite, kaolinite and chlorite are selected as the clay mineral particles for filling, and quartz and feldspar with a mass proportion of 51% and 33% respectively in Table 1 are selected as the rock skeleton particles for filling. The particle size of quartz and feldspar is 40 mesh.

[0153] Step S502: Filling rock skeleton particles to form an uncemented core model constructed by the rock skeleton.

[0154] Specifically, after the bottom surface of the transmissive shell is sealed with a sand-proof net, 200g of quartz sand particles and feldspar particles are weighed and placed in the transmissive shell, and axial pressure is applied for compaction. The pressure treatment starts at 6MPa and increases by 1MPa every 2h until the axial pressure reaches 15MPa, so that the rock particles of the transmissive shell are fully compacted. Then, the core wrapped by the transmissive shell after pressurization is placed in a 100℃ thermostat and heated for 24h to form an uncemented core model built by a rock skeleton.

[0155] Step S503: Chromium acetate and a temperature-resistant polymer are selected to prepare a bonding chemical solution A (ie, a first bonding solution).

[0156] Step S504: inject the cementing chemical solution A into the uncemented core model by using the displacement device to implement effective consolidation under low pressure conditions to form an incompletely cemented core model. The displacement confining pressure is set to 3 MPa, and the displacement cycle exceeds 10 PV.

[0157] Step S505: Select clay minerals to prepare a cementing chemical solution B (ie, a second cementing solution).

[0158] Specifically, 80 g of clay mineral particles are weighed and gradually poured into 800 mL of distilled water and stirred thoroughly, and NaHCO3 powder is stirred in to form a clay mineral suspension. The clay mineral suspension is then placed in a cleaning machine, and the mixed suspension is vibrated with 30 Hz sound waves. During this process, a small amount of NaOH powder is added, and the upper suspension in the suspension is taken to measure the pH value. When the pH value reaches 8, the suspension can be made into a cementing chemical solution B.

[0159] Step S506: Use the displacement device to inject the cementing chemical solution B into the incompletely cemented core model to implement effective consolidation under medium and high pressure conditions to form a completely cemented core model. The displacement confining pressure is set to 3Mpa, and the displacement cycle exceeds 10 PV.

[0160] For example, the cementing chemical solution B can be gradually poured into the incompletely cemented core model, and the water can be continuously dried in a constant temperature box. When the mass of the evaporated rock reaches 240 g, the pouring of the clay mineral suspension is stopped.

[0161] Step S507: The fully cemented core model is placed in a constant temperature box and heated at 100° C. for 24 hours to allow clay minerals to adhere to the surface of the rock skeleton, completing the core making process and obtaining a non-intrusive visualized core model.

[0162] The core model is a regular cylinder with a bottom radius of 2.5 cm and a height of 5 cm.

[0163] The fifth embodiment of the present invention further provides a displacement simulation experimental method, which comprises the following steps:

[0164] Step S'501: Place the obtained non-intrusive visualized core model into a core holder, select carbon dioxide + steam + water-soluble viscosity reducer solution as a displacement agent, connect various parts of the displacement simulation experimental system and test the air tightness of the device.

[0165] Step S'502: Testing the porosity, permeability and initial water saturation of the core model.

[0166] (1) Carry out the saturated water process with an injection flow rate of 0.5 mL / min. After the pressure and water production are stable, record the pressure difference as 0.001×10 -1 MPa, and the permeability is calculated using Darcy's formula to be 733mD.

[0167] (2) Take out the core model and use the mass difference before and after saturation with water (23.76 g) to calculate the porosity to be 0.242.

[0168] (3) After saturation with water, the oil saturation process was carried out at an injection rate of 0.25 mL / min. The core model was then placed in a constant temperature box at the formation temperature for 144 h to simulate the reservoir aging process. The difference in mass between produced water and saturated water was 20.17 g, and the initial water saturation was calculated to be 15%.

[0169] Step S'503: Inject fluid into the core model to simulate the oil and gas reservoir development process, and record the pressure, temperature and production.

[0170] Specifically, the steam generator was turned on to inject steam at a rate of 0.1 mL / min, the gas flow controller was turned on to inject carbon dioxide gas at an injection rate of 0.1 mL / min, and the high-precision single-cylinder displacement plunger pump was turned on to inject water-soluble viscosity reducer solution at an injection rate of 0.1 mL / min to simulate the reservoir development process until the water content reached 95%, and then the high-precision double-cylinder displacement plunger pump was turned off to stop fluid injection, and the pressure, temperature and production change data during the process were recorded. The thermostat was closed, and after the temperature dropped to room temperature, the vent valve of the six-way valve was opened to relieve pressure.

[0171] Step S'504: After the simulation development process is completed, the oil and water distribution inside the core model is observed using nuclear magnetic resonance, and the effects of different fluids on different types of clay minerals are analyzed based on the nuclear magnetic resonance results.

[0172] Specifically, after the pressure and temperature return to normal levels, the core model with the permeable shell is taken out and the displacement process is completed. By analyzing the nuclear magnetic resonance test results during the displacement process, the oil and water distribution is observed, and the impact of the composite flooding of hot gas (steam + carbon dioxide gas + water-soluble viscosity reducer solution) on the development of rock models simulating real oil reservoirs is analyzed.

[0173] The preferred embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0174] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0175] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A method for making a non-intrusive visual core model, characterized in that: The production method comprises: Determine the type of rock skeleton particles and clay mineral particles based on simulated strata; The rock skeleton particles are filled in the encapsulation shell, and after pressure treatment and heating treatment, an uncemented core model constructed by the rock skeleton is formed; The chromium acetate and the temperature-resistant polymer are prepared according to a preset ratio to form a first cementing solution; Injecting the first cementing solution into the uncemented core model and solidifying it according to a preset displacement confining pressure and a preset displacement cycle to form an incompletely cemented core model; preparing clay mineral particles and NaHCO3 solution to form a second cementing solution; The second cementing solution is injected into the incompletely cemented core model, and solidified according to a preset displacement confining pressure and a preset displacement cycle to form a completely cemented core model.

2. The method for making a non-intrusive visual core model according to claim 1, characterized in that: The rock skeleton particles are at least one of quartz sand and feldspar; the clay mineral particles are at least one of montmorillonite, kaolinite, illite and chlorite.

3. The method for making a non-intrusive visual core model according to claim 1, characterized in that: The packaging shell is made of a transmissive material or a semi-transmissive material.

4. The method for making a non-intrusive visualized core model according to claim 3, characterized in that: The wrapping shell is a polyetheretherketone shell.

5. The method for making a non-intrusive visualized core model according to claim 1, characterized in that: The heat-resistant polymer is polyacrylamide with a temperature resistance of more than 90°C.

6. The method for making a non-intrusive visualized core model according to claim 1, characterized in that: The step of preparing the clay mineral particles and the NaHCO3 solution to form a second cementing solution comprises: Put the clay mineral particles into NaHCO3 solution and stir it continuously to form a cement suspension; The cement suspension is vibrated and NaOH powder is added until the pH value of the upper suspension in the cement suspension is greater than 8, thereby obtaining a second cement solution.

7. The method for making a non-intrusive visualized core model according to claim 1, characterized in that: The manufacturing method further comprises: drying the incompletely cemented core model and / or the completely cemented core model.

8. A non-intrusive visual core model, characterized in that: The core model is made according to the method for making a non-intrusive visualized core model according to any one of claims 1 to 7.

9. A displacement simulation experimental system, characterized in that: Used to carry out displacement simulation experiment on the core model described in claim 8, the displacement simulation experiment system comprises: a displacement power device, a nuclear magnetic scanning device and a data acquisition device; The displacement power device is used to inject steam and various fluids into the core model to simulate the development process of the reservoir in the multi-component composite flooding; The nuclear magnetic resonance scanning device is used to obtain the oil and water distribution identification results inside the non-intrusive visual core model during the displacement process; The data acquisition device is used to acquire displacement data, and the displacement data includes pressure, temperature and production measurement.

10. A displacement simulation experimental method, characterized in that: Applied to the displacement simulation experiment system according to claim 9, the displacement simulation experiment method comprises: Connecting the non-intrusive visualized core model to a displacement power device to test the basic physical properties of the core, wherein the basic physical properties of the core include the porosity, permeability and initial water saturation of the core model; Different fluids are injected into the non-intrusive visual core model to simulate the development process of the reservoir in multi-component flooding. During the flooding process, the nuclear magnetic resonance scanning device is used to obtain the oil and water distribution identification results inside the non-intrusive visual core model; Based on the oil-water distribution identification results, the displacement effects of different fluids on different pore fillings are analyzed.

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