In-situ high temperature and high pressure water displacement test device and test method suitable for CT scanning

Abstract

This invention discloses an in-situ high-temperature and high-pressure water displacement testing device and method suitable for CT scanning, belonging to the field of rock physics experiments. The in-situ high-temperature and high-pressure water displacement testing device for CT scanning includes a radiation source, a detector, and an in-situ high-temperature and high-pressure water displacement testing apparatus located on a rotating stage within the CT scanning area formed by the radiation source and detector. The testing apparatus includes a rubber tube fixed to the outside of the core sample, and a PEEK sleeve, a non-metallic heating layer, and a non-metallic thermal insulation layer sequentially arranged outside the rubber tube. The two ends of the test cavity enclosed by the PEEK sleeve are respectively sealed and connected to a displacement loading component and a synchronous monitoring component. Using the above-mentioned in-situ high-temperature and high-pressure water displacement testing device and method suitable for CT scanning, a high degree of synergy can be achieved between in-situ high-temperature and high-pressure water displacement, CT synchronous microscopic imaging, and real-time quantification of the recovery degree.

Description

Technical Field

[0001] This invention relates to the field of rock physics experimental technology, and in particular to an in-situ high-temperature and high-pressure water displacement test apparatus and test method applicable to CT scanning. Background Technology

[0002] In the fields of energy and geological engineering, such as oil and gas field development, shale gas exploration, and CO2 geological storage, core samples are the core microscopic samples that characterize the features of underground reservoirs. Their fluid seepage characteristics (such as fluid flow rate and multiphase fluid distribution patterns) directly determine the reservoir development efficiency and the feasibility of engineering schemes.

[0003] Core displacement testing is a core technical means to study reservoir seepage characteristics. Only by accurately simulating the real occurrence environment of underground strata with high temperature and high pressure can reliable experimental data that closely match the field conditions be obtained.

[0004] The introduction of CT scanning technology has enabled the visualization and observation of the evolution of pore structure inside the core, the tracking of fluid migration paths, and the characterization of multiphase fluid distribution during displacement. This provides an intuitive basis for the microscopic analysis of displacement mechanisms and has become the mainstream technical method in experimental research in this field.

[0005] However, existing conventional core displacement equipment faces significant technical bottlenecks in its compatibility with CT scan in-situ experiments, making it difficult to meet the needs of integrated testing. The main problems are as follows: First, severe imaging interference: the core load-bearing components of traditional displacement equipment have a high attenuation rate for X-rays, easily generating artifacts during scanning and obscuring the true internal structure and fluid distribution information of the core. Second, incompatible device sizes: the cavity space of CT scan equipment is limited, and conventional displacement equipment is too large to fit, and the sample compatibility is poor, easily resulting in problems such as the scanning field of view not covering the entire core and insufficient imaging resolution. Third, asynchronous process detection: the displacement process and recovery degree measurement are separated, easily missing key characteristics of fluid production stages, making it impossible to accurately identify core displacement mechanisms such as crossflow and sweep efficiency, thus leading to misjudgment of the effectiveness of the displacement scheme, reducing displacement efficiency and increasing development costs. Summary of the Invention

[0006] The purpose of this invention is to provide an in-situ high-temperature and high-pressure water displacement test device and test method suitable for CT scanning, thereby solving the above-mentioned technical problems.

[0007] To achieve the above objectives, the present invention provides an in-situ high-temperature and high-pressure water displacement test device suitable for CT scanning, including a radiation source, a detector, and an in-situ high-temperature and high-pressure water displacement test device located on a rotating stage within the CT scanning area formed by the radiation source and the detector. The in-situ high-temperature and high-pressure water displacement test device includes a rubber tube fixed to the outside of the core sample and a PEEK sleeve, a non-metallic heating layer, and a non-metallic thermal insulation layer sequentially arranged outside the rubber tube. The test cavity enclosed by the PEEK sleeve has two ends sealed to the displacement loading component and the synchronous monitoring component respectively through a three-level sealing assembly. The displacement loading component, the synchronous monitoring component, and the non-metallic heating layer are all electrically connected to the data processing module.

[0008] Preferably, the synchronous monitoring component includes a temperature monitoring unit, a dielectric monitoring unit, and a flow monitoring unit sequentially disposed on the produced fluid outflow pipeline connected to the displacement fluid outlet of the test chamber. The temperature monitoring unit, dielectric monitoring unit, and flow monitoring unit are used to monitor the real-time temperature, equivalent dielectric parameter, and mass flow rate of the produced fluid, respectively. The monitoring signals of the three units are synchronously transmitted to the data processing module for temperature and flow correction of the dielectric parameter.

[0009] The end of the produced fluid outlet pipe that is furthest from the displacing fluid outlet extends into the measuring cylinder, and the produced fluid outlet pipe is an insulated non-metallic pipe.

[0010] The produced fluid outflow pipeline between the synchronous monitoring component and the displacement fluid outlet is also equipped with a displacement outlet valve, which is connected to the data processing module.

[0011] Preferably, the temperature monitoring unit is a temperature sensor embedded in the produced fluid outflow pipeline;

[0012] The dielectric monitoring unit consists of a first annular electrode and a second annular electrode axially and sequentially mounted on the produced fluid outflow pipeline. The first annular electrode and the second annular electrode use the produced fluid as the dielectric to form a non-contact parallel plate capacitor. Both the first annular electrode and the second annular electrode are connected to the data processing module via a signal excitation and acquisition module.

[0013] The flow monitoring unit is a mass flow meter.

[0014] Preferably, the axial width of the first annular electrode and the second annular electrode is 5 mm, and the axial distance between the first annular electrode and the second annular electrode is 10 mm.

[0015] Preferably, the displacement loading assembly includes a displacement constant pressure constant flow pump and a displacement confining pressure pump that are sealed and connected to both ends of the test chamber. A pressure sensor and a confining pressure inlet valve are sequentially arranged between the displacement confining pressure pump and the test chamber. A temperature and pressure monitoring unit and a displacement inlet valve are sequentially arranged between the displacement constant pressure constant flow pump and the test chamber. The pressure sensor, the confining pressure inlet valve, the temperature and pressure monitoring unit, and the displacement inlet valve are all connected to the data processing module.

[0016] The input terminals of the displacement constant pressure constant flow pump are connected to the water phase and the oil phase, respectively.

[0017] Preferably, the three-stage sealing assembly includes a screw, an O-ring, and a threaded pair, arranged sequentially from the outside to the inside between the end of the PEEK sleeve and the connecting seat;

[0018] The connecting seat at the bottom is fixed to the rotating platform;

[0019] The end of the test chamber facing the displacement constant pressure constant flow pump is also provided with a radial flow splitting component. The radial flow splitting component includes a flow splitting column sealed inside the test chamber and multiple flow splitting holes axially and uniformly opened on the flow splitting column in a circumferential array.

[0020] Preferably, the non-metallic heating layer is a polyimide film heating tape spirally wound around the outer circumference of the PEEK sleeve;

[0021] The winding spacing of the polyimide film heating belt is 5mm.

[0022] Preferably, the non-metallic thermal insulation layer includes a vacuum insulation layer and a ceramic fiber aluminum silicate thermal insulation layer arranged sequentially from the inside to the outside.

[0023] The test method for an in-situ high-temperature and high-pressure water displacement test device suitable for CT scanning includes the following steps:

[0024] S1. Load the clean and dry core sample into the test chamber to complete the assembly and sealing of the in-situ high temperature and high pressure water displacement test equipment;

[0025] S2. Fix the assembled in-situ high temperature and high pressure water displacement test equipment at the center of the rotary table in the CT scanning area.

[0026] S3. Turn on the non-metallic heating layer, heat the core sample to the in-situ temperature of the formation, and then maintain it.

[0027] S4. Vacuum the test chamber and all fluid pipelines for at least 12 hours.

[0028] S5. Apply confining pressure to the test chamber to the in-situ formation pressure using a displacement confining pressure pump, stabilize the pressure for more than 2 hours, and perform the first CT scan on the dry core sample.

[0029] S6. Heated and pressurized formation water was injected into the test chamber by a displacement constant pressure constant flow pump to continuously saturate the core sample for 48 hours.

[0030] S7. Inject the oil phase into the core sample at a constant rate until no water flows out of the displacement fluid outlet, so that the core sample reaches the state of bound water.

[0031] S8. Conduct a constant-rate water displacement experiment and perform a second CT scan on the core sample using the same parameters as the CT scan in step S5.

[0032] S9. Adjust the displacement rate or the amount of injected fluid, repeat the displacement operation step S8, and record the core scanning images under different working conditions.

[0033] S10. Collect real-time capacitance values ​​through the dielectric monitoring unit and calculate the original equivalent dielectric constant of the extracted fluid;

[0034] S11. Based on the real-time monitoring signals from the temperature monitoring unit and the flow monitoring unit, the equivalent dielectric constant is corrected by both temperature and mass flow rate.

[0035] S12. Based on the corrected results from step S11, the volume fraction of the aqueous phase in the produced fluid is calculated using a mixed dielectric model to obtain the degree of water displacement recovery.

[0036] Preferably, the original equivalent dielectric constant of the produced fluid in step S10 is... The calculation formula is as follows:

[0037] ;

[0038] In the formula, The reference capacitor; The real-time capacitance value collected by the dielectric monitoring unit;

[0039] In step S11, the expression for temperature correction of the equivalent dielectric constant is as follows:

[0040] ;

[0041] In the formula, The dielectric constant is based on temperature correction. The real-time monitored temperature collected by the temperature monitoring unit; Reference temperature; This is a temperature correction factor;

[0042] The expression for mass flow rate correction to the equivalent dielectric constant is as follows:

[0043] ;

[0044] In the formula, The dielectric constant is the result of dual correction for temperature and mass flow rate. This is the flow correction factor; Real-time quality flow rate collected by the flow monitoring unit; The baseline mass flow rate;

[0045] The expression for the hybrid dielectric model described in step S12 is as follows:

[0046] ;

[0047] In the formula, The theoretical equivalent dielectric constant of the mixed medium; This represents the volume fraction of the aqueous phase. The dielectric constant of the aqueous phase; The dielectric constant of the oil phase;

[0048] The formula for inverting the volume fraction of aqueous phase in the produced liquid is:

[0049] ;

[0050] Water Displacement Recovery The calculation formula is as follows:

[0051] ;

[0052] in,

[0053] ;

[0054] ;

[0055] In the formula, This represents the cumulative volume of oil produced. This represents the original oil-bearing volume; The total pore volume of the core obtained by CT scanning of a dry core sample; This represents the volume of water bound in the core. This represents the total volume of the extracted fluid. This represents the volume fraction of the oil phase.

[0056] Therefore, the present invention employs the above-mentioned in-situ high-temperature and high-pressure water displacement test device and test method suitable for CT scanning, which has the following beneficial effects:

[0057] 1. Interference-free and high-precision CT imaging: Using low X-ray absorption non-metallic materials such as PEEK sleeve, PI film heating belt (polyimide film heating belt), and ceramic fiber insulation layer, the scan is free of artifacts and does not obscure the core area. The imaging error of the core edge is ≤0.03mm, which meets the requirements of micro-seepage observation.

[0058] 2. Strong adaptability to in-situ temperature and pressure conditions: The device can withstand high temperature of 280℃ and high pressure of over 100MPa, and the deformation rate is ≤0.5% under confining pressure of 50MPa; the PI film heating belt is spirally wound (contact area ≥90%) + double-layer insulation structure, the temperature control is uniform and there is no local overheating, accurately simulating the real temperature and pressure environment of the formation.

[0059] 3. Reliable sealing and stable displacement process: The three-stage sealing structure eliminates confining pressure crossflow and fluid leakage; confining pressure loading ensures that the rubber sleeve fits tightly against the core to eliminate interface effects, radial flow diversion achieves uniform fluid spread, eliminates the high-speed zone at the inlet, and improves the stability of the displacement front.

[0060] 4. Reasonable monitoring cabling and no mechanical interference: The monitoring cables are routed along the edge of the base and connected to the external acquisition box to avoid tangling of the CT rotating stage tubing; the sensors are all made of non-metallic materials and have an external layout, which do not occupy the core scanning area and do not interfere with CT imaging.

[0061] 5. Real-time and accurate recovery degree measurement: The non-contact annular two-electrode structure is non-corrosive and non-polarized, and can continuously detect the dielectric properties of the produced fluid; combined with temperature + mass flow rate dual correction and a hybrid dielectric model, it can realize real-time recovery degree inversion without separation or interruption of the displacement process, and the data error is controllable.

[0062] 6. Closed-loop experimental data with high reliability: It achieves synchronous matching of three data: CT microscopic imaging, real-time dielectric monitoring, and macroscopic measurement with graduated cylinder. Dry sample CT calibration of pore volume and real-time monitoring calculation of recovery rate are performed. The data is complete and repeatable, providing reliable support for the study of displacement mechanism.

[0063] In summary, this invention employs the aforementioned in-situ high-temperature and high-pressure water displacement testing device and method suitable for CT scanning, enabling continuous and real-time measurement of the recovery rate in water-driven oil experiments, and ensuring the authenticity and accuracy of experimental data. It is applicable to the study of core micro-displacement characteristics in fields such as oil and gas development and geological exploration.

[0064] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0065] Figure 1 This is a schematic diagram of the overall structure of the in-situ high-temperature and high-pressure water displacement test device applicable to CT scanning as described in this invention.

[0066] Figure 2 This is a schematic diagram of the in-situ high-temperature and high-pressure water displacement test device applicable to CT scanning as described in this invention.

[0067] Figure 3 This is a diagram showing the arrangement of the synchronous monitoring components of the in-situ high-temperature and high-pressure water displacement test device applicable to CT scanning as described in this invention.

[0068] Figure 4 This is a schematic diagram of the radial flow splitter component of the in-situ high-temperature and high-pressure water displacement test device applicable to CT scanning as described in this invention.

[0069] Figure Labels

[0070] 1. X-ray source; 2. Detector; 3. In-situ high-temperature and high-pressure water displacement test equipment; 31. Displacement constant pressure and constant flow pump; 32. Radial flow splitter assembly; 321. Flow splitter orifice; 33. PEEK sleeve; 34. Rubber hose; 35. Non-metallic heating layer; 36. Three-stage sealing assembly; 361. Threaded pair; 362. Screw; 363. O-ring sleeve; 37. Non-metallic thermal insulation layer; 371. Vacuum insulation layer; 372. Ceramic fiber aluminum silicate thermal insulation layer; 38. Produced fluid outflow pipeline; 39. Synchronous monitoring assembly; 391. Temperature monitoring unit; 392. Dielectric monitoring unit; 3921. First annular electrode; 3922. Second annular electrode; 393. Flow monitoring unit; 310. Displacement confining pressure pump; 311. Measuring cylinder; 4. Core sample; 5. Rotary stage; 6. CT scanning area. Detailed Implementation

[0071] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are merely illustrative of the embodiments of the present invention and are not intended to limit the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of this application. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout.

[0072] It should be noted that the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion, such as a process, method, system, product, or server that includes a series of steps or units, not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such process, method, product, or device.

[0073] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0074] like Figures 1-4As shown, the in-situ high-temperature and high-pressure water displacement test device suitable for CT scanning includes a radiation source 1, a detector 2, and an in-situ high-temperature and high-pressure water displacement test equipment 3 located within the CT scanning area 6 formed by the radiation source 1 and the detector 2 and situated on a rotating stage 5. The in-situ high-temperature and high-pressure water displacement test equipment 3 includes a rubber tube 34 fixed to the outside of the core sample 4, and a PEEK (polyether ether ketone) sleeve, a non-metallic heating layer 35, and a non-metallic thermal insulation layer 37 sequentially arranged outside the rubber tube 34. The test cavity enclosed by the PEEK sleeve 33 has two ends sealed to the displacement loading component and the synchronous monitoring component 39 respectively via a three-stage sealing assembly 36. The displacement loading component, the synchronous monitoring component 39, and the non-metallic heating layer 35 are all electrically connected to the data processing module. The rubber tube 34 is made of fluororubber, possessing oil resistance, high-temperature resistance, and high-pressure sealing performance, and can completely conform to the outer wall of the core sample. PEEK sleeve 33 is CT scan compatible. It is a special engineering plastic material that is resistant to high temperature and chemical corrosion. It can withstand the corrosion of various displacing fluids, avoiding swelling, degradation and performance decay. In addition, the material has an extremely low absorption coefficient for X-rays, so it will not produce artifacts during scanning and will not obscure the internal target area.

[0075] The synchronous monitoring component 39 includes a temperature monitoring unit 391, a dielectric monitoring unit 392, and a flow monitoring unit 393, which are sequentially installed on the produced fluid outflow pipe 38, which is connected to the displacement fluid outlet of the test chamber. The temperature monitoring unit 391, the dielectric monitoring unit 392, and the flow monitoring unit 393 are used to monitor the real-time temperature, equivalent dielectric parameter, and mass flow rate of the produced fluid, respectively. The monitoring signals of the three units are synchronously transmitted to the data processing module for temperature and flow correction of the dielectric parameter. The end of the produced fluid outflow pipe 38 away from the displacement fluid outlet extends into the measuring cylinder 311, and the produced fluid outflow pipe 38 is an insulated non-metallic pipe. The produced fluid outflow pipe 38 between the synchronous monitoring component 39 and the displacement fluid outlet is also equipped with a displacement outlet valve, which is connected to the data processing module.

[0076] Temperature monitoring unit 391 is a temperature sensor embedded in the produced fluid outflow pipe 38; dielectric monitoring unit 392 consists of a first annular electrode 3921 and a second annular electrode 3922 axially sleeved on the produced fluid outflow pipe 38, with the produced fluid serving as the dielectric to form a non-contact parallel plate capacitor; both the first annular electrode 3921 and the second annular electrode 3922 are connected to the data processing module via a signal excitation and acquisition module; flow monitoring unit 393 is a mass flow meter, with the inner walls of both the first annular electrode 3921 and the second annular electrode 3922 adhered to the outside of the produced fluid outflow pipe 38.

[0077] The first annular electrode 3921 and the second annular electrode 3922 each have an axial width of 5 mm, ensuring a sufficient electric field area and avoiding edge electric field distortion. The axial distance between the first annular electrode 3921 and the second annular electrode 3922 is 10 mm, avoiding the problems of electric field concentration and low signal-to-noise ratio caused by too small a distance, and the problems of unstable detection volume and reduced resolution caused by too large a distance. In this embodiment, the signal excitation and acquisition module applies an alternating voltage to the first annular electrode 3921, and the second annular electrode 3922 serves as a signal receiving electrode. A stable, uniform, and repeatable alternating electric field is formed in the sampled fluid between the two electrodes and inside the insulating tube, thereby realizing the sensing of changes in the dielectric properties of the sampled fluid in a non-contact manner through the alternating electric field, and converting the "oil / water mixing ratio" into electrical signals of "capacitance, impedance, and phase angle".

[0078] The displacement loading assembly includes a displacement constant pressure constant flow pump 31 and a displacement confining pressure pump 310, which are sealed and connected to both ends of the test chamber. A pressure sensor and a confining pressure inlet valve are sequentially installed between the displacement confining pressure pump 310 and the test chamber. A temperature and pressure monitoring unit and a displacement inlet valve are sequentially installed between the displacement constant pressure constant flow pump 31 and the test chamber. The pressure sensor, confining pressure inlet valve, temperature and pressure monitoring unit, and displacement inlet valve are all connected to the data processing module. The input end of the displacement constant pressure constant flow pump 31 is connected to the water phase and the oil phase, respectively.

[0079] The three-stage sealing assembly 36 includes a screw 362, an O-ring 363, and a threaded pair 361, which are arranged sequentially from the outside to the inside between the end of the PEEK sleeve 33 and the connecting seat; the connecting seat at the bottom end is fixed on the rotating table 5.

[0080] The end of the test chamber facing the displacement constant pressure constant flow pump 31 is also provided with a radial flow splitting component 32. The radial flow splitting component 32 includes a flow splitting column sealed inside the test chamber and multiple flow splitting holes 321 that are axially uniformly opened in a circumferential array on the flow splitting column. It is used to spread the displacement fluid evenly on the core end face, eliminate the local high-speed zone of the inlet fluid, and improve the stability of the displacement front.

[0081] The non-metallic heating layer 35 is a polyimide film heating strip spirally wound around the outer circumference of the PEEK sleeve 33; the winding spacing of the polyimide film heating strip is 5mm. The polyimide (PI) film heating element is made of non-metallic material, which has minimal impact on X-ray penetration, avoiding scanning artifacts caused by the heating device. Moreover, it adopts a spiral winding arrangement, with the PI film heating element spirally wound along the axial direction of the PEEK sleeve 33 at a winding spacing of 5mm. This method allows the contact area between the heating element and the outer wall of the sleeve to reach more than 90%, avoiding local overheating that could lead to uneven core temperature.

[0082] The non-metallic thermal insulation layer 37 includes a vacuum insulation layer 371 and a ceramic fiber aluminum silicate thermal insulation layer 372 arranged sequentially from the inside to the outside. The main component of the ceramic fiber aluminum silicate thermal insulation layer 372 is a lightweight inorganic material that does not significantly absorb or scatter X-rays.

[0083] It should be noted that the aforementioned electronic products are all mature products on the market. This embodiment only requires purchasing them and connecting them according to the instructions; no modifications have been made. Therefore, their circuit connection structure and principle will not be described in detail here. Furthermore, in this embodiment, all traces pass through the edge axis of the bottom connector and then electrically connect to the external data processing module via a slip ring, avoiding the problem of cable entanglement caused by spin.

[0084] The test method for an in-situ high-temperature and high-pressure water displacement test device suitable for CT scanning includes the following steps:

[0085] S1. Load the clean and dry core sample into the test chamber to complete the assembly and sealing of the in-situ high temperature and high pressure water displacement test equipment;

[0086] S2. Fix the assembled in-situ high temperature and high pressure water displacement test equipment at the center of the rotary table in the CT scanning area.

[0087] S3. Turn on the non-metallic heating layer, heat the core sample to the in-situ temperature of the formation, and then maintain it.

[0088] S4. Vacuum the test chamber and all fluid pipelines for at least 12 hours.

[0089] S5. Apply confining pressure to the test chamber to the in-situ formation pressure using the displacement confining pressure pump, stabilize the pressure for more than 2 hours, and perform the first CT scan on the dry core sample to ensure that the hose is tightly attached to the core sample, avoid the interface effect, and ensure that the displacement fluid penetrates evenly along the height of the core.

[0090] S6. Heated and pressurized formation water was injected into the test chamber by a displacement constant pressure constant flow pump to continuously saturate the core sample for 48 hours.

[0091] S7. Inject the oil phase into the core sample at a constant (low) speed until no water flows out of the displacement fluid outlet, so that the core sample reaches the state of bound water.

[0092] S8. Conduct a constant-rate water displacement experiment and perform a second CT scan on the core sample using the same parameters as the CT scan in step S5.

[0093] S9. Adjust the displacement rate or the amount of injected fluid, repeat the displacement operation step S8, and record the core scanning images under different working conditions.

[0094] S10. Collect real-time capacitance values ​​through the dielectric monitoring unit and calculate the original equivalent dielectric constant of the extracted fluid;

[0095] S11. Based on the real-time monitoring signals from the temperature monitoring unit and the flow monitoring unit, the equivalent dielectric constant is corrected by both temperature and mass flow rate.

[0096] S12. Based on the corrected results from step S11, the volume fraction of the aqueous phase in the produced fluid is calculated using a mixed dielectric model to obtain the degree of water displacement recovery.

[0097] Preferably, the original equivalent dielectric constant of the produced fluid in step S10 is... The calculation formula is as follows:

[0098] ;

[0099] In the formula, The reference capacitor; The real-time capacitance value collected by the dielectric monitoring unit;

[0100] In step S11, the expression for temperature correction of the equivalent dielectric constant is as follows:

[0101] ;

[0102] In the formula, The dielectric constant is based on temperature correction. The real-time monitored temperature collected by the temperature monitoring unit; Reference temperature; This is a temperature correction factor;

[0103] The expression for mass flow rate correction to the equivalent dielectric constant is as follows:

[0104] ;

[0105] In the formula, The dielectric constant is the result of dual correction for temperature and mass flow rate. This is the flow correction factor; Real-time quality flow rate collected by the flow monitoring unit; The baseline mass flow rate;

[0106] The expression for the hybrid dielectric model described in step S12 is as follows:

[0107] ;

[0108] In the formula, The theoretical equivalent dielectric constant of the mixed medium; This represents the volume fraction of the aqueous phase. The dielectric constant of the aqueous phase; The dielectric constant of the oil phase;

[0109] The formula for inverting the volume fraction of aqueous phase in the produced liquid is:

[0110] ;

[0111] Water Displacement Recovery The calculation formula is as follows:

[0112] ;

[0113] in,

[0114] ;

[0115] ;

[0116] In the formula, This represents the cumulative volume of oil produced. This represents the original oil-bearing volume; The total pore volume of the core obtained by CT scanning of a dry core sample; This represents the volume of water bound in the core. This represents the total volume of the extracted fluid. This represents the volume fraction of the oil phase.

[0117] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. An in-situ high temperature and high pressure water flooding test device suitable for CT scanning, characterized in that: The test equipment includes a radiation source, a detector, and an in-situ high-temperature and high-pressure water displacement test device located on a rotating stage within the CT scanning area formed by the radiation source and the detector. The in-situ high-temperature and high-pressure water displacement test device includes a rubber tube fixed to the outside of the core sample and a PEEK sleeve, a non-metallic heating layer, and a non-metallic thermal insulation layer arranged sequentially on the outside of the rubber tube. The test chamber formed by the PEEK sleeve is sealed to the displacement loading component and the synchronous monitoring component at both ends by a three-level sealing assembly. The displacement loading component, the synchronous monitoring component, and the non-metallic heating layer are all electrically connected to the data processing module. The synchronous monitoring component includes a temperature monitoring unit, a dielectric monitoring unit, and a flow monitoring unit sequentially installed on the produced fluid outflow pipeline connected to the displacement fluid outlet of the test chamber. The temperature monitoring unit, dielectric monitoring unit, and flow monitoring unit are used to monitor the real-time temperature, equivalent dielectric parameter, and mass flow rate of the produced fluid, respectively. The monitoring signals of the three units are synchronously transmitted to the data processing module for temperature and flow correction of the dielectric parameter. The end of the produced fluid outlet pipe that is furthest from the displacing fluid outlet extends into the measuring cylinder, and the produced fluid outlet pipe is an insulated non-metallic pipe. The produced fluid outflow pipeline between the synchronous monitoring component and the displacement fluid outlet is also equipped with a displacement outlet valve, which is connected to the data processing module. The displacement loading assembly includes a displacement constant pressure constant flow pump and a displacement confining pressure pump that are sealed and connected to both ends of the test chamber. A pressure sensor and a confining pressure inlet valve are sequentially installed between the displacement confining pressure pump and the test chamber. A temperature and pressure monitoring unit and a displacement inlet valve are sequentially installed between the displacement constant pressure constant flow pump and the test chamber. The pressure sensor, confining pressure inlet valve, temperature and pressure monitoring unit, and displacement inlet valve are all connected to the data processing module. The input terminals of the displacement constant pressure constant flow pump are connected to the water phase and the oil phase, respectively; The three-stage sealing assembly includes, from the outside to the inside, a screw, an O-ring, and a threaded pair, which are arranged sequentially between the end of the PEEK sleeve and the connecting seat; The connecting seat at the bottom is fixed to the rotating platform; The end of the test chamber facing the displacement constant pressure constant flow pump is also provided with a radial flow splitting component. The radial flow splitting component includes a flow splitting column sealed inside the test chamber and multiple flow splitting holes axially and uniformly opened on the flow splitting column in a circumferential array.

2. The in-situ high-temperature and high-pressure water displacement test device suitable for CT scanning according to claim 1, characterized in that: The temperature monitoring unit is a temperature sensor embedded in the produced fluid outflow pipeline; The dielectric monitoring unit consists of a first annular electrode and a second annular electrode axially and sequentially mounted on the produced fluid outflow pipeline. The first annular electrode and the second annular electrode use the produced fluid as the dielectric to form a non-contact parallel plate capacitor. Both the first annular electrode and the second annular electrode are connected to the data processing module via a signal excitation and acquisition module. The flow monitoring unit is a mass flow meter.

3. The in-situ high-temperature and high-pressure water displacement test device suitable for CT scanning according to claim 2, characterized in that: The first and second annular electrodes each have an axial width of 5 mm, and the axial distance between the first and second annular electrodes is 10 mm.

4. The in-situ high-temperature and high-pressure water displacement test device suitable for CT scanning according to claim 3, characterized in that: The non-metallic heating layer is a polyimide film heating strip spirally wound around the outer circumference of the PEEK sleeve; The winding spacing of the polyimide film heating belt is 5mm.

5. The in-situ high-temperature and high-pressure water displacement test apparatus suitable for CT scanning according to claim 4, characterized in that: The non-metallic thermal insulation layer includes a vacuum insulation layer and a ceramic fiber aluminum silicate thermal insulation layer arranged sequentially from the inside to the outside.

6. The test method of the in-situ high-temperature and high-pressure water displacement test device applicable to CT scanning as described in claim 5, characterized in that: Includes the following steps: S1. Load the clean and dry core sample into the test chamber to complete the assembly and sealing of the in-situ high temperature and high pressure water displacement test equipment; S2. Fix the assembled in-situ high temperature and high pressure water displacement test equipment at the center of the rotary table in the CT scanning area. S3. Turn on the non-metallic heating layer, heat the core sample to the in-situ temperature of the formation, and then maintain it. S4. Vacuum the test chamber and all fluid pipelines for at least 12 hours. S5. Apply confining pressure to the test chamber to the in-situ formation pressure using a displacement confining pressure pump, stabilize the pressure for more than 2 hours, and perform the first CT scan on the dry core sample. S6. Heated and pressurized formation water was injected into the test chamber by a displacement constant pressure constant flow pump to continuously saturate the core sample for 48 hours. S7. Inject the oil phase into the core sample at a constant rate until no water flows out of the displacement fluid outlet, so that the core sample reaches the state of bound water. S8. Conduct a constant-rate water displacement experiment and perform a second CT scan on the core sample using the same parameters as the CT scan in step S5. S9. Adjust the displacement rate or the amount of injected fluid, repeat the displacement operation step S8, and record the core scanning images under different working conditions. S10. Collect real-time capacitance values ​​through the dielectric monitoring unit and calculate the original equivalent dielectric constant of the extracted fluid; S11. Based on the real-time monitoring signals from the temperature monitoring unit and the flow monitoring unit, the equivalent dielectric constant is corrected by both temperature and mass flow rate. S12. Based on the corrected results from step S11, the volume fraction of the aqueous phase in the produced fluid is calculated using a mixed dielectric model to obtain the degree of water displacement recovery.

7. The test method for the in-situ high-temperature and high-pressure water displacement test apparatus applicable to CT scanning according to claim 6, characterized in that: The original equivalent dielectric constant of the produced fluid mentioned in step S10 The calculation formula is as follows: ； In the formula, The reference capacitor; The real-time capacitance value collected by the dielectric monitoring unit; In step S11, the expression for temperature correction of the equivalent dielectric constant is as follows: ； In the formula, The dielectric constant is based on temperature correction. The real-time monitored temperature collected by the temperature monitoring unit; Reference temperature; This is a temperature correction factor; The expression for mass flow rate correction to the equivalent dielectric constant is as follows: ； In the formula, The dielectric constant is the result of dual correction for temperature and mass flow rate. This is the flow correction factor; Real-time quality flow rate collected by the flow monitoring unit; The baseline mass flow rate; The expression for the hybrid dielectric model described in step S12 is as follows: ； In the formula, The theoretical equivalent dielectric constant of the mixed medium; This represents the volume fraction of the aqueous phase. The dielectric constant of the aqueous phase; The dielectric constant of the oil phase; The formula for inverting the volume fraction of aqueous phase in the produced liquid is: ； Water Displacement Recovery The calculation formula is as follows: ； in, ； ； In the formula, This represents the cumulative volume of oil produced. This represents the original oil-bearing volume; The total pore volume of the core obtained by CT scanning of a dry core sample; This represents the volume of water bound in the core. This represents the total volume of the extracted fluid. This represents the volume fraction of the oil phase.

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