Simulation device and method for calculating dynamic filtration coefficient of supercritical carbon dioxide fracturing fluid
The dynamic filtration coefficient of supercritical carbon dioxide fracturing fluid was calculated by using simulation devices and methods, which solved the problem that existing technologies could not fully measure and simulate the fluid, optimized fracturing parameters, and improved fracturing performance.
Patent Information
- Application Number
- CN202410555368.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-05-07
- Publication Date
- 2025-11-07
Smart Images
Figure CN120908027A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the field of unconventional oil and gas stimulation technology, more particularly, it relates to a simulation device and method for calculating the dynamic filtration coefficient of supercritical carbon dioxide fracturing fluid. BACKGROUND
[0002] As a new unconventional oil and gas reservoir reconstruction technology, supercritical carbon dioxide (SC-CO2) fracturing has great advantages compared to conventional hydraulic fracturing technology, such as incomplete gel breaking, incomplete flowback, and serious reservoir damage. It is an important means to improve the conductivity of unconventional oil and gas reservoirs and realize the commercial exploitation of unconventional oil and gas resources. Moreover, supercritical CO2 has the potential for reservoir reconstruction, carbon utilization, and carbon sequestration. Under the guidance of the "double carbon" goal, supercritical CO2 fracturing technology has broad application prospects.
[0003] Under formation conditions, carbon dioxide is usually in a supercritical state (critical temperature of 31.3℃, critical pressure of 7.3MPa). Super critical carbon dioxide fracturing fluid has many characteristics such as small formation damage, viscosity reduction, anti-swelling, drag reduction, and cleanup aid. Under the condition of a certain amount of injected fluid, if the filtration coefficient is too large, the amount of filtration will be more, resulting in a decrease in fracture width and length, and a smaller fracture volume, which reduces the effective utilization rate of fracturing fluid. If the filtration coefficient is too small, the filtration rate will be slow, which will cause the proppant to gradually deposit in the fracture, easily forming sand plugs, affecting the uniform distribution of proppant in the fracture, and not being able to support the fracture height, resulting in unsatisfactory stimulation effect. Therefore, the key parameter for supercritical carbon dioxide fracturing design is to determine the filtration coefficient of supercritical carbon dioxide fracturing fluid.
[0004] At present, the device research for the filtration coefficient of supercritical carbon dioxide gas fracturing fluid in the laboratory does not consider enough factors, cannot measure the filtration coefficient of supercritical carbon dioxide fracturing fluid under different shear rates and different additive ratios corresponding to different viscosities, and cannot simulate the migration of proppant in supercritical carbon dioxide fracturing fluid. According to the characteristics of field operation, the measurement of static filtration coefficient cannot fully reflect the actual situation. At present, the calculation method for the dynamic filtration coefficient of supercritical carbon dioxide fracturing fluid under formation conditions is simple, and does not characterize the formation stress field to calculate a more realistic dynamic filtration coefficient. Therefore, there is an urgent need for a measuring device and method that can achieve the above functions. SUMMARY
[0005] The application aims to provide a simulation device and method for calculating the dynamic filtration coefficient of supercritical carbon dioxide fracturing fluid, which is used for measuring the dynamic filtration coefficient of supercritical carbon dioxide fracturing fluid under different fracturing fluid viscosities, temperatures, pressures, pressure differences and shear rates, establishing a dynamic filtration coefficient calculation method by characterizing the formation stress field, and realizing the simulation of supercritical carbon dioxide fracturing fluid migration and proppant, thereby providing effective technical support for the application of supercritical carbon dioxide fracturing in unconventional oil and gas development.
[0006] The above technical purpose of the application is achieved by the following technical scheme:
[0007] In a first aspect, the application provides a simulation device for calculating the dynamic filtration coefficient of supercritical carbon dioxide fracturing fluid, which comprises a cooling injection system and a balanced reaction system, and the output end of the cooling injection system is connected to the balanced reaction system; the balanced reaction system is further connected to a temperature and pressure control system and a coefficient calculation system, wherein:
[0008] The coefficient calculation system comprises a filtration instrument and a core holder, the core holder is located in the interior of the filtration instrument, and the filtration instrument is further provided with a differential pressure sensor for measuring the differential pressure between the front end and the rear end thereof; the coefficient calculation system further comprises a back pressure valve, a back pressure pump and a nitrogen cylinder, one end of the back pressure valve is connected to the back pressure pump and the nitrogen cylinder in sequence, and the other end of the back pressure valve is connected to the liquid outlet end of the filtration instrument; the coefficient calculation system further comprises a flow meter and a calculation end, the input end of the flow meter is connected to the liquid outlet end of the filtration instrument, the output end of the flow meter is connected to the calculation end, the calculation end is used for measuring and recording the obtained experimental calculation parameters, and the calculation end comprises a piston container, an electronic balance and a computer connected in sequence, and the piston container is connected to the flow meter.
[0009] The coefficient calculation system is used for calculating the experimental calculation parameters of the dynamic filtration coefficient of different viscosity fracturing fluids in the system under different core conditions under the control of the temperature and pressure control system.
[0010] The simulation device in the application comprises a cooling injection system, a balanced reaction system, a temperature and pressure control system and a coefficient calculation system, wherein: the cooling injection system liquefies gaseous carbon dioxide and then injects it into the balanced reaction system to mix with additives of a certain proportion prepared in advance, and then the balanced reaction system injects the mixed fluid into the coefficient calculation system; under the control of the temperature and pressure control system on the temperature, pressure and differential pressure in the coefficient calculation system, the experimental calculation parameters of the dynamic filtration coefficient of different viscosity fracturing fluids in the system under different core conditions can be calculated.
[0011] In the scheme, the simulation device can simulate and test the filtration degree of the supercritical carbon dioxide fracturing fluid formed by different additive ratios and liquefied carbon dioxide under different temperatures, different pressures, different pressure differentials and different shear rates, and the filtration degree of the fracturing fluid to the reservoir core, through the characterization of the formation stress field, a dynamic filtration coefficient calculation method is established, which provides effective experimental support for the optimization design of the fracturing hydraulic parameters; the filtration of the supercritical carbon dioxide fracturing fluid in the unconventional oil and gas reservoir fracturing stimulation engineering is realized, the dynamic filtration coefficient of the supercritical carbon dioxide fracturing fluid is determined, and the filtration capacity of the supercritical carbon dioxide fracturing fluid is evaluated.
[0012] Based on the above technical scheme, the application can be further improved as follows.
[0013] Further, the above-mentioned cooling injection system comprises a carbon dioxide gas storage tank, the output end of the carbon dioxide gas storage tank is sequentially connected with an air inlet control valve, a gas purifier, an air inlet pressure gauge, a circulating cooling device, an air inlet valve, an air inlet booster pump and an inlet liquid check valve, the check valve is also connected to the balance reaction system.
[0014] Further, the above-mentioned balance reaction system comprises a balance reaction kettle and a magnetic stirrer, the magnetic stirrer is located in the balance reaction kettle and stirs and mixes the liquid carbon dioxide and the fracturing fluid additive injected through the inlet liquid check valve;
[0015] The balance reaction system further comprises an additive injection structure, the additive injection structure comprises an additive tank, a reagent valve, a reagent pump and a reagent check valve which are sequentially connected, and the output end of the reagent check valve is connected to the balance reaction kettle.
[0016] Further, the above-mentioned temperature and pressure control system comprises a heating pipeline, a confining pressure pump and a thermostat, the output end of the confining pressure pump is connected to the filtration instrument, the balance reaction kettle and the filtration instrument located in the thermostat are connected through the heating pipeline, the heating pipeline comprises a safety valve, a preheater and a circulating pump, one end of the safety valve is sequentially connected with the preheater and the circulating pump, the other end of the safety valve is connected with the balance reaction kettle, the output end of the circulating pump is connected with the filtration instrument, and the output end of the circulating pump is further provided with an inlet thermometer and an inlet pressure gauge.
[0017] Further, the above-mentioned simulation device further comprises a fracturing fluid recovery system, the fracturing fluid recovery system comprises a separation tank, a refrigerator, a filter and a recovery tank, the input end of the separation tank is connected with the liquid outlet end of the filtration instrument, one of the output ends of the separation tank is sequentially connected with the refrigerator, the filter and the recovery tank.
[0018] Further, the other end of the safety valve is further connected with the output end of the proppant filling, and the input end of the proppant filling is connected with the other output end of the separation tank.
[0019] The beneficial effect of the further scheme is that the filter loss ability of the supercritical carbon dioxide fracturing fluid under different influencing factors is evaluated by simulating the migration of the proppant in the supercritical carbon dioxide fracturing fluid.
[0020] In the second aspect, the application provides a method for calculating the dynamic filter loss coefficient of a supercritical carbon dioxide fracturing fluid, which is applied to the simulation device for calculating the dynamic filter loss coefficient of a supercritical carbon dioxide fracturing fluid according to any one of the first aspect, and includes the following specific steps:
[0021] After the simulation device is detected by the air-tight seal, the liquefied carbon dioxide is injected into the equilibrium reaction system by using the cooling injection system;
[0022] The pre-prepared additive with a preset ratio is fully mixed with the liquefied carbon dioxide by using the equilibrium reaction system;
[0023] The fluid obtained after mixing is preheated by using the temperature and pressure control system, and the preheated fluid is injected into the filter loss instrument;
[0024] The temperature and pressure of the core holder clamped in the filter loss instrument are regulated by the temperature and pressure control system, and the pressure difference between the front and rear ends of the filter loss instrument is regulated by the back pressure pump and the nitrogen cylinder, and a plurality of filter loss amounts under different temperatures, different pressures, different pressure differences, different fracturing fluid viscosities and different core conditions are recorded;
[0025] The experimental calculation parameters under the condition are calculated by the change curve of each filter loss amount with time, and the dynamic filter loss coefficient under the condition is calculated by each experimental calculation parameter.
[0026] Further, the above method further includes:
[0027] The dynamic filter loss optimal coefficient is obtained, and the experimental parameters corresponding to the dynamic filter loss optimal coefficient are obtained by inversion of the simulation device, the experimental parameters including temperature data, pressure data, pressure difference data, fracturing fluid viscosity data and core type data;
[0028] The simulation device is run based on the experimental parameters, and the preset proppant is added to the filter loss instrument, and the dynamic filter loss optimal coefficient is verified according to the sand production or sand plugging of the preset proppant.
[0029] Further, the dynamic filter loss coefficient under the condition is calculated by each experimental calculation parameter, and specifically:
[0030]
[0031] C = C1+ C2+ C3, wherein C represents a dynamic filtration coefficient, C1 represents a filtration coefficient affected by the viscosity of the fracturing fluid, C2 represents a filtration coefficient affected by the compressibility of the reservoir fluid, and C3 represents a filtration coefficient affected by the wall-building effect of the fracturing fluid.
[0032] Further, the filtration coefficient affected by the viscosity of the fracturing fluid is specifically:
[0033] wherein:
[0034] wherein C1 represents a filtration coefficient affected by the viscosity of the fracturing fluid, K represents the average permeability of the reservoir, φ represents the original porosity of the reservoir, μ1 represents the viscosity of the fracturing fluid, ΔP e represents the pressure difference inside and outside the fracture, P i represents the pressure at the perforation of the wellbore, P c represents the fracture closure pressure, t represents the initial time of opening of any node on the fracture, and T represents the total fracturing time.
[0035] The filtration coefficient affected by the compressibility of the reservoir fluid is specifically:
[0036] wherein: t = S g C g + S w C w + C f ;
[0037] wherein C2 represents a filtration coefficient affected by the compressibility of the reservoir fluid, K2 represents the average permeability of the reservoir, C t represents the overall compressibility of the reservoir, φ represents the original porosity of the reservoir, μ2 represents the viscosity of the fluid inside the reservoir, S g represents the gas saturation of the reservoir, S w represents the water saturation, C g represents the gas compressibility of the reservoir, C w represents the water compressibility, and C f represents the pore volume compressibility of the reservoir.
[0038] The filtration coefficient affected by the wall-building effect of the fracturing fluid is specifically:
[0039] wherein:
[0040] wherein C3 represents a filtration coefficient affected by the wall-building effect of the fracturing fluid, C 3e represents a filtration correction coefficient obtained through experiments, ΔP e represents the pressure difference inside and outside the fracture, ΔP c represents the stress difference of the experiment, A represents the cross-sectional area flowing through the filtration instrument, and m represents an experimental calculation parameter.
[0041] In a third aspect, the present application provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and capable of running on the processor, and the processor implements the method of any one of the second aspect when executing the computer program.
[0042] In a fourth aspect, the present application provides a non-transitory computer readable storage medium, which stores computer instructions, and the computer instructions make the computer execute the method of any one of the second aspect.
[0043] Compared with the prior art, the present application has at least the following beneficial effects:
[0044] In the present application, the simulation device is composed of a cooling injection system, a balanced reaction system, a temperature and pressure control system, and a coefficient calculation system, wherein: the cooling injection system liquefies gaseous carbon dioxide and then injects it into the balanced reaction system to mix with an additive of a certain proportion, and then the balanced reaction system injects the mixed fluid into the coefficient calculation system; under the control of the temperature and pressure control system on the temperature, pressure, pressure difference and other parameters in the system, the coefficient calculation system can measure and calculate the experimental calculation parameters of the different viscosity fracturing fluids in the system for calculating the dynamic filtration coefficient under different core conditions.
[0045] In the present application, the simulation device can simulate and test the filtration degree of the supercritical carbon dioxide fracturing fluid formed by different additive proportions and liquefied carbon dioxide under different temperatures, different pressures, different pressure differences and different shear rates, and through the characterization of the formation stress field, the dynamic filtration coefficient calculation method is established to provide effective experimental support for the optimization design of fracturing hydraulic parameters; and the migration of the supercritical carbon dioxide fracturing fluid supporting agent is simulated, so as to realize the filtration capacity evaluation of the supercritical carbon dioxide fracturing fluid under different influencing factors, realize the filtration of the supercritical carbon dioxide fracturing fluid in the unconventional oil and gas reservoir fracturing stimulation engineering, determine the dynamic filtration coefficient of the supercritical carbon dioxide fracturing fluid, and thus evaluate the filtration capacity of the supercritical carbon dioxide fracturing fluid. BRIEF DESCRIPTION OF DRAWINGS
[0046] The accompanying drawings, which are included to provide a further understanding of the embodiments of the application and constitute a part of this application, illustrate embodiments of the application and do not limit the application. In the drawings:
[0047] Figure 1 It is a connection diagram of the simulation device in the embodiments of the present application;
[0048] Figure 2 It is a schematic diagram of the filtration amount and filtration time change curve in the embodiments of the present application;
[0049] Figure 3 The flow chart of the method for calculating the dynamic filtration coefficient of the supercritical carbon dioxide fracturing fluid in the embodiment of the present application.
[0050] The marks in the drawings and the corresponding names of parts:
[0051] 1, carbon dioxide gas storage tank; 2, gas inlet control valve; 3, gas purifier; 4, gas inlet pressure gauge; 5, circulating cooling device; 6, gas inlet valve; 7, gas inlet booster pump; 8, liquid inlet check valve; 9, balance reaction kettle; 10, magnetic stirrer; 11, additive tank; 12, reagent valve; 13, reagent pump; 14, reagent check valve; 15, safety valve; 16, preheater; 17, circulating pump; 18, filtration instrument; 19, inlet thermometer; 20, inlet pressure gauge; 21, thermostat; 22, differential pressure sensor; 23, confining pressure pump; 24, core holder; 25, back pressure valve; 26, back pressure pump; 27, nitrogen cylinder; 28, flow meter; 29, piston container; 30, electronic balance; 31, computer; 32, separation tank; 33, proppant tank; 34, refrigerator; 35, filter; 36, recovery tank. DETAILED DESCRIPTION
[0052] In order to make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations.
[0053] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative labor are within the scope of protection of the present application.
[0054] It should be noted that: similar marks and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.
[0055] In the description of the embodiments of the present application, it should be noted that if the terms "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the present application is usually placed, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.
[0056] In addition, if the terms "horizontal", "vertical", "overhanging" and the like appear, they do not mean that the component must be absolutely horizontal or overhanging, but can be slightly inclined. For example, "horizontal" only means that it is more horizontal relative to "vertical", and does not mean that the structure must be completely horizontal, but can be slightly inclined.
[0057] In the description of the embodiments of the present application, "a plurality of" represents at least 2.
[0058] In the description of the embodiments of the present application, it should be noted that unless otherwise explicitly specified and limited, if the terms "arrangement", "installation", "connection", "connection" appear, they should be understood in a broad sense, for example, they can be fixedly connected, or can be detachably connected, or integrally connected; can be mechanically connected, or can be electrically connected; can be directly connected, or can be indirectly connected through an intermediate medium; can be connected inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.
[0059] Embodiment 1: In order to realize the simulation of the migration of the supercritical carbon dioxide fracturing fluid supporting agent, the dynamic filtration coefficient of the supercritical carbon dioxide fracturing fluid is calculated to provide effective technical support for the application of supercritical carbon dioxide fracturing in unconventional oil and gas development, the simulation device for calculating the dynamic filtration coefficient of the supercritical carbon dioxide fracturing fluid is provided, which comprises a cooling injection system and a balanced reaction system, the output end of the cooling injection system is connected to the balanced reaction system, the cooling injection system liquefies the gaseous carbon dioxide and then injects it into the balanced reaction system to mix with the additives of a certain proportion prepared in advance; The balanced reaction system is also connected with a temperature and pressure control system and a coefficient calculation system.
[0060] Optionally, the above-mentioned cooling injection system comprises a carbon dioxide gas storage tank 1, the output end of the carbon dioxide gas storage tank 1 is connected with a gas inlet control valve 2, a gas purifier 3, a gas inlet pressure gauge 4, a circulating cooling device 5, a gas inlet valve 6, a gas inlet booster pump 7 and a liquid inlet check valve 8 in sequence, and the check valve is also connected to the balanced reaction system.
[0061] Optionally, the above-mentioned balanced reaction system comprises a balanced reaction kettle 9 and a magnetic stirrer 10, which is located in the balanced reaction kettle 9 and stirs and mixes the liquid carbon dioxide and the fracturing fluid additive injected through the liquid inlet one-way valve 8; the balanced reaction system further comprises an additive injection structure, which comprises an additive tank 11, a reagent valve 12, a reagent pump 13 and a reagent one-way valve 14 connected in sequence, and the output end of the reagent one-way valve 14 is connected to the balanced reaction kettle 9.
[0062] Optionally, the above-mentioned temperature and pressure control system comprises a heating pipeline, a confining pressure pump 23 and a thermostat 21, the output end of the confining pressure pump 23 is connected to the filter press 18, the balanced reaction kettle 9 and the filter press 18 located in the thermostat 21 are connected through the heating pipeline, the heating pipeline comprises a safety valve 15, a preheater 16 and a circulating pump 17, one end of the safety valve 15 is connected to the preheater 16 and the circulating pump 17 in sequence, the other end of the safety valve 15 is connected to the balanced reaction kettle 9, the output end of the circulating pump 17 is connected to the filter press 18, and the output end of the circulating pump 17 is further provided with an inlet thermometer 19 and an inlet pressure gauge 20.
[0063] The coefficient measurement system comprises a filter press 18 and a core holder 24, the core holder 24 is located in the inside of the filter press 18, the core holder 24 is used for clamping cores of different materials or types, and the filter press 18 is further provided with a differential pressure sensor 22 for measuring the pressure difference between the front end and the rear end, as shown in Figure 1 The coefficient measurement system further comprises a back pressure valve 25, a back pressure pump 26 and a nitrogen cylinder 27, one end of the back pressure valve 25 is connected to the back pressure pump 26 and the nitrogen cylinder 27 in sequence, the other end of the back pressure valve 25 is connected to the liquid outlet end of the filter press 18, the liquid outlet end is connected to the back pressure pump 26 and the nitrogen cylinder 27 through the back pressure valve 25, so as to provide back pressure for the experiment; the coefficient measurement system further comprises a flow meter 28 and a measurement end, the input end of the flow meter 28 is connected to the liquid outlet end of the filter press 18, the output end of the flow meter 28 is connected to the measurement end, the measurement end is used for measuring and recording the obtained experimental measurement parameters, and the measurement end comprises a piston container 29, an electronic balance 30 and a computer 31 connected in sequence, the piston container 29 is connected to the flow meter 28, the piston container 29 and the electronic balance 30 measure the filtration amount, the electronic balance 30 is connected to the computer 31, and the collected experimental data is recorded in real time.
[0064] The coefficient measurement system is used for measuring the experimental measurement parameters of the fracturing fluid with different viscosities in the system under different core conditions for calculating the dynamic filtration coefficient under the control of the temperature and pressure control system.
[0065] Optionally, the simulation device further comprises a fracturing fluid recovery system, the fracturing fluid recovery system comprises a separation tank 32, a refrigerator 34, a filter 35 and a recovery tank 36, an input end of the separation tank 32 is connected to a liquid outlet end of the filtration instrument 18, one output end of the separation tank 32 is connected to the refrigerator 34, the filter 35 and the recovery tank 36 in sequence; wherein the other end of the safety valve 15 is further connected to an output end of the proppant filling 33, and an input end of the proppant filling 33 is connected to the other output end of the separation tank 32.
[0066] Specifically, the carbon dioxide gas storage tank 1 is connected with the gas inlet control valve 2, as shown in Figure 1 , the carbon dioxide gas is purified by the gas purifier 3, the pipeline pressure is monitored by the gas inlet pressure gauge 4, then the carbon dioxide is refrigerated and liquefied by the circulating cooling device 5, the circulating cooling device 5 is connected with the gas inlet valve 6, then the gas is pressurized by the gas booster pump, when the fluid is pressurized to a certain degree, the fluid enters the balance reaction kettle 9 through the liquid inlet check valve 8; the additives of different proportions in the additive tank 11 are controlled to enter the pipeline through the reagent valve 12, the reagent pump 13 is connected with the reagent check valve 14, the additives are pumped into the balance reaction kettle 9 by the reagent pump 13, the fracturing fluid (liquid carbon dioxide) and the additives are fully mixed by the magnetic stirrer 10 in the balance reaction kettle 9, and the mixed fluid enters the pipeline through the safety valve 15 together with the proppant in the proppant tank, as shown in Figure 1 , the mixed fluid is heated by the preheater 16, then enters the filtration instrument 18 through the circulating pump 17, the inside and the liquid inlet of the filtration instrument 18 are respectively provided with an inlet thermometer 19 and an inlet pressure gauge 20, the outside of the filtration instrument 18 is controlled by the thermostat 21, the front end and the rear end of the filtration instrument 18 are respectively connected with the input ends of the pressure difference sensor 22, at the same time, the inside of the filtration instrument 18 applies the confining pressure to the core clamped by the core holder 24 through the confining pressure pump 23, so as to provide the pressure condition required by the experiment, the core holder 24 is located in the cavity of the filtration instrument 18, the filtration liquid outlet end of the filtration instrument 18 is connected with the back pressure pump 26 and the nitrogen cylinder 27 in sequence through the back pressure valve 25, so as to provide the back pressure for the experiment; the other filtration liquid outlet end of the filtration instrument 18 is connected with the flowmeter 28, the filtration amount is measured by the piston container 29 and the electronic balance 30, the electronic balance 30 is connected with the computer 31, and the experimental data collected in real time are recorded; at the same time, the fracturing fluid outlet end of the filtration instrument 18 is further connected with the separation tank 32, the proppant separated by the separation tank 32 is recovered into the proppant filling 33, the carbon dioxide is cooled by the refrigerator 34, then enters the recovery tank 36 through the filter 35 for recovery treatment.
[0067] Embodiment 2: In order to calculate the dynamic filtration coefficient of the supercritical carbon dioxide fracturing fluid, to provide effective technical support for the application of supercritical carbon dioxide fracturing in unconventional oil and gas development, the embodiment provides a method for calculating the dynamic filtration coefficient of the supercritical carbon dioxide fracturing fluid, which is applied to the simulation device for calculating the dynamic filtration coefficient of the supercritical carbon dioxide fracturing fluid in any one of Embodiment 1, as shown in Figure 3 The method comprises the following specific steps:
[0068] S1, after the simulation device is detected by the gas tightness, the liquefied carbon dioxide is injected into the balance reaction system by using the cooling injection system.
[0069] Wherein, the gas tightness of the whole pipeline and the core holder 24 should be checked before the experiment; when checking the gas tightness of the core holder 24, a steel core with the same size as the core can be put into the core holder 24 to simulate the filtration experiment, and whether there is gas flowing out of the outlet end is detected; if so, it indicates that the sealing is not good, or there is a gap between the core and the rubber sleeve, or the sealing of each part is not good; otherwise, it indicates that the sealing is good.
[0070] S2, the pre-prepared pre-proportioned additive is fully mixed with the liquefied carbon dioxide by using the balance reaction system.
[0071] S3, the fluid obtained after mixing is preheated by using the temperature and pressure control system, and the preheated fluid is injected into the filtration instrument 18.
[0072] Specifically, after the gas tightness is detected, the circulating cooling device 5 in the cooling injection system is started, when the temperature of the cooling water in the circulating cooling device 5 reaches the set temperature, the carbon dioxide gas storage tank 1 and the gas inlet control valve 2 are opened to release CO2 gas, the CO2 gas is liquefied through the circulating cooling device 5, and then is pressurized into the balance reaction kettle 9 through the gas booster pump, the different proportion of additives is prepared to realize the addition of the additive tank 11, the additive is pumped into the balance reaction kettle 9 through the reagent pump 13 to fully stir with the carbon dioxide fracturing fluid, at the same time, the thermostat 21 is opened, the required temperature is set, the circulating pump 17 is opened, and the pressurized and preheated liquid CO2 starts to circulate into the filtration instrument 18.
[0073] S4, the temperature and pressure of the core clamped by the core holder 24 in the filtration instrument 18 are regulated by the temperature and pressure control system, and the pressure difference between the front and rear ends of the filtration instrument 18 is regulated by the back pressure pump 26 and the nitrogen cylinder 27, and a plurality of filtration amounts under different temperature, pressure, pressure difference, fracturing fluid viscosity and different core conditions are recorded.
[0074] S5, the experimental parameters under the condition are calculated through the change curve of the filtration loss of each over time, and the dynamic filtration coefficient under the condition is calculated through the experimental parameters.
[0075] Optionally, the method further comprises:
[0076] S51, the dynamic filtration optimal coefficient is obtained, and the experimental parameters corresponding to the dynamic filtration optimal coefficient are obtained through the inversion of the simulation device. The experimental parameters include temperature data, pressure data, differential pressure data, fracturing fluid viscosity data, and core type data.
[0077] S52, the simulation device is run based on the experimental parameters, and the preset proppant is added to the filter press 18. The dynamic filtration optimal coefficient is verified according to the sand production or sand plugging of the preset proppant.
[0078] Wherein, when performing experimental test, the computer 31 is opened and the experimental system is started, the experiment is started when the temperature and pressure reach the set value and are stable, the temperature and pressure data of the core at different positions are automatically recorded by the inlet thermometer 19 and the inlet pressure gauge 20 at certain time intervals, and the experimental time is recorded. The differential pressure sensor 22 monitors the differential pressure change in the experimental process; since the filtration differential pressure, fluid properties, shear rate, core permeability, temperature, pressure and other factors are important factors affecting filtration, when the filtration under different differential pressures needs to be measured, the size of back pressure can be changed through the back pressure pump 26, that is, different differential pressures can be obtained; the fracturing fluid with different viscosities can be adjusted according to the different additive ratios in the additive tank 11; at the same time, different cores can be replaced to measure the influence of different permeabilities on the filtration; if the filtration under different shear rates needs to be tested, the operating frequency of the circulating pump 17 can be changed; by setting different temperatures of the thermostat 21 and pressures of the confining pressure pump 23, the filtration under different temperatures and pressures can be measured; the fracturing fluid filtration is accurately measured through the flowmeter 28, the piston container 29 and the electronic balance 30, and the experimental data is transmitted to the computer 31 in real time, so as to draw the relationship curve of the filtration Vsp and the time t, as shown in Figure 2 After the experimental parameters corresponding to the optimal filtration coefficient are determined, the proppant used in the operation is added to the proppant storage tank to simulate the migration of the proppant in the supercritical carbon dioxide fracturing fluid, and the sand production or sand plugging of the proppant is observed to verify the experimental results.
[0079] Specifically, after the experiment is completed, the circulating pump 17 and the safety valve 15 of the liquid inlet end of the core holder 24 should be turned off, the refrigerator 34 and the filter 35 in the fracturing fluid recovery system are turned on, the fracturing fluid is recovered and treated, and the experimental device is cleaned, and then the experiment is completed.
[0080] Optionally, the dynamic filtration coefficient under this condition is calculated using the parameters measured in the various experiments, as follows:
[0081]
[0082] In the formula, C represents the dynamic filtration coefficient, m / min 0.5 C1 represents the filtration loss coefficient affected by fracturing fluid viscosity, in m / min. 0.5 C2 represents the filtration loss coefficient affected by reservoir fluid compressibility, in m / min. 0.5 C3 represents the filtration coefficient affected by the wall-building effect of fracturing fluid, in m / min. 0.5 .
[0083] In the classical filtration theory, the filtration loss of fracturing fluid during hydraulic fracturing needs to be considered in conjunction with three factors: filtration viscosity, formation fluid compressibility, and fracturing fluid wall-building properties. The amount of fracturing fluid filtration loss is often expressed by the magnitude of the filtration coefficients: C1, which is affected by the viscosity of the fracturing fluid; C2, which is affected by the compressibility of the reservoir fluid; and C3, which is affected by the wall-building properties of the fracturing fluid.
[0084] Specifically, the filtration loss of fracturing fluid is controlled by three mechanisms simultaneously, and the overall filtration loss coefficient is: The formula for calculating the comprehensive dynamic filtration coefficient can be obtained from the partial pressure drop formula:
[0085] Optionally, the filtration loss coefficient affected by the fracturing fluid viscosity mentioned above is specifically as follows:
[0086] in:
[0087] In the formula, C1 represents the filtration loss coefficient affected by the fracturing fluid viscosity, in m / min. 0.5 K is the average reservoir permeability, MPa; φ is the original reservoir porosity, %; μ1 is the fracturing fluid viscosity, Pa·s; ΔP e P represents the pressure difference between the inside and outside of the crack, in MPa; i P represents the pressure at the wellbore perforation point, in MPa; c t represents the fracture closure pressure, MPa; t represents the initial time for any node on the fracture to open, min; T represents the total fracturing time, min.
[0088] During hydraulic fracturing, the formation stress field can be characterized by the net fracture pressure and fracturing time. The stress difference between the inside and outside of the hydraulic fracture can be expressed as the difference between the net reservoir fracture pressure, the closure pressure, and the original formation pore pressure. The pressure difference between the inside and outside of the fracture can be expressed as: ΔP e =ΔP+P cP1(1), wherein: ΔP is the net pressure of the fracture during the hydraulic fracturing process, MPa; P1 is the original formation pore pressure, MPa; P c is the fracture closure pressure, MPa. According to the stress state and the attenuation law of the fracture during the extension process, the change relation of the net pressure ΔP about the position x can be expressed by the following formula:
[0089]
[0090] wherein: P i is the pressure at the wellbore perforation, MPa; l is the fracture extension distance, m; x is the position at any place in the fracture from the wellbore wall, m; wherein, wherein: t is the initial time of the opening of any node of the fracture, min; T is the total fracturing time, min; m is the fracture extension index, dimensionless; according to the research of Nordgren on the fracture extension index, under the condition of considering the filtration effect of the fracturing fluid, m is usually taken as 0.5 to describe the fracture extension process. The relation of the net pressure of the fracture during the hydraulic fracturing process and the fracturing time can be obtained by combining formula (2) and formula (3): Substituting formula (4) into formula (1) can obtain:
[0091] Further, the filtration coefficient affected by the compressibility of the reservoir fluid is specifically:
[0092] wherein: C t = S g C g + S w C w + C f ;
[0093] wherein, C2 represents the filtration coefficient affected by the compressibility of the reservoir fluid, m / min 0.5 ; K2 represents the average permeability of the reservoir, MPa; C t represents the comprehensive compression coefficient of the reservoir, MPa -1 ; φ represents the original porosity of the reservoir, %; μ2 represents the viscosity of the fluid inside the reservoir, Pa.S; S g is the gas saturation of the reservoir, %; S w is the water saturation, %; C g is the gas compression coefficient of the reservoir, MPa -1 ; C w is the water compression coefficient, MPa -1 ; C f is the pore volume compression coefficient of the reservoir.
[0094] Further, the filtration coefficient affected by the wall-building effect of the fracturing fluid is specifically:
[0095] wherein:
[0096] wherein, C3 represents the filtration coefficient under the effect of the fracturing fluid wall-building property, m / min 0.5 ; C 3e represents the filtration correction coefficient obtained from the experiment, m / min 0.5 ; ΔP e represents the pressure difference inside and outside the fracture, MPa; ΔP c represents the stress difference in the experiment, MPa; A represents the cross-sectional area through which the filtration instrument flows, cm 2 ; m represents the experimental calculation parameter, i.e., the tangent slope of the filtration amount-time curve in the experiment, dimensionless, as shown in Figure 2 .
[0097] Example 3: The example provides a system for calculating the dynamic filtration coefficient of supercritical carbon dioxide fracturing fluid, applied to the method for calculating the dynamic filtration coefficient of supercritical carbon dioxide fracturing fluid in any one of example 2, comprising:
[0098] The first module is configured to inject the liquefied carbon dioxide into the equilibrium reaction system by using the cooling injection system after the simulation device is detected by the gas tightness.
[0099] The second module is configured to fully mix the pre-prepared additive with the preset proportion and the liquefied carbon dioxide by using the equilibrium reaction system.
[0100] The third module is configured to preheat the fluid obtained after mixing by using the temperature and pressure control system, and inject the preheated fluid into the filtration instrument 18.
[0101] The fourth module is configured to adjust the temperature and pressure of the core clamped by the core holder 24 in the filtration instrument 18 by the temperature and pressure control system, and adjust the pressure difference between the front and rear ends of the filtration instrument 18 by the back pressure pump 26 and the nitrogen cylinder 27, and record a plurality of filtration amounts under different temperatures, different pressures, different pressure differences, different fracturing fluid viscosities and different core conditions.
[0102] The fifth module is configured to calculate the experimental calculation parameter under the condition by the change curve of each filtration amount with time, and calculate the dynamic filtration coefficient under the condition by each experimental calculation parameter.
[0103] The example provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, and the processor implements the method in any one of example 2 when executing the computer program.
[0104] The embodiment of the application further provides a non-transitory computer readable storage medium, the non-transitory computer readable storage medium stores computer instructions, and the computer instructions cause a computer to execute the method in any one of the embodiments 2.
[0105] The above detailed description of the specific embodiments of the application has further explained the purposes, technical solutions and beneficial effects of the application. It should be understood that the above detailed description is only a specific embodiment of the application and is not used to limit the protection scope of the application. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the application should be included in the protection scope of the application.
Claims
1. A simulation device for calculating the dynamic filtration coefficient of supercritical carbon dioxide fracturing fluid, characterized in that, The cooling injection system and the balance reaction system are connected, and the output end of the cooling injection system is connected to the balance reaction system; the balance reaction system is also connected with a temperature and pressure control system and a coefficient measuring system, wherein: The coefficient measuring system comprises a filter loss instrument and a core holder, the core holder is located in the filter loss instrument, and the filter loss instrument is also provided with a differential pressure sensor for measuring the differential pressure between the front and rear ends thereof; the coefficient measuring system further comprises a back pressure valve, a back pressure pump and a nitrogen cylinder, one end of the back pressure valve is connected with the back pressure pump and the nitrogen cylinder in sequence, the other end of the back pressure valve is connected with the liquid outlet end of the filter loss instrument; the coefficient measuring system further comprises a flow meter and a measuring end, the input end of the flow meter is connected with the liquid outlet end of the filter loss instrument, the output end of the flow meter is connected with the measuring end, the measuring end is used for measuring and recording the experimental and calculated parameters obtained, and the measuring end comprises a piston container, an electronic balance and a computer connected in sequence, and the piston container is connected with the flow meter; The coefficient measuring system is used for measuring the experimental and calculated parameters of the dynamic filtration coefficient of the fracturing fluid with different viscosities in different cores under the control of the temperature and pressure control system.
2. The simulation device for calculating the dynamic filtration coefficient of supercritical carbon dioxide fracturing fluid according to claim 1, characterized in that, The cooling injection system comprises a carbon dioxide gas storage tank, and the output end of the carbon dioxide gas storage tank is connected with a gas inlet control valve, a gas purifier, a gas inlet pressure gauge, a circulating cooling device, a gas inlet valve, a gas inlet booster pump and a liquid inlet check valve in sequence, and the check valve is connected to the balance reaction system.
3. The simulation device for calculating the dynamic filtration coefficient of supercritical carbon dioxide fracturing fluid according to claim 2, characterized in that, The balance reaction system comprises a balance reaction kettle and a magnetic stirrer, the magnetic stirrer is located in the balance reaction kettle, and the liquid carbon dioxide and the fracturing fluid additives injected through the liquid inlet check valve are stirred and mixed; The balance reaction system further comprises an additive injection structure, the additive injection structure comprises an additive tank, a reagent valve, a reagent pump and a reagent check valve connected in sequence, and the output end of the reagent check valve is connected to the balance reaction kettle.
4. The simulation device for calculating the dynamic filtration coefficient of supercritical carbon dioxide fracturing fluid according to claim 3, characterized in that, The temperature and pressure control system comprises a heating pipeline, a confining pressure pump and a thermostat, the output end of the confining pressure pump is connected to the filter loss instrument, the balance reaction kettle and the filter loss instrument located in the thermostat are connected through the heating pipeline, the heating pipeline comprises a safety valve, a preheater and a circulating pump, one end of the safety valve is connected with the preheater and the circulating pump in sequence, the other end of the safety valve is connected with the balance reaction kettle, the output end of the circulating pump is connected with the filter loss instrument, and the output end of the circulating pump is also provided with an inlet thermometer and an inlet pressure gauge.
5. The simulation device for calculating the dynamic filtration coefficient of supercritical carbon dioxide fracturing fluid according to claim 4, characterized in that, The simulation device further comprises a fracturing fluid recovery system, the fracturing fluid recovery system comprises a separation tank, a refrigeration machine, a filter and a recovery tank, the input end of the separation tank is connected with the liquid outlet end of the filter loss instrument, one of the output ends of the separation tank is connected with the refrigeration machine, the filter and the recovery tank in sequence.
6. The simulation device for calculating the dynamic filtration coefficient of supercritical carbon dioxide fracturing fluid according to claim 5, characterized in that, The other end of the safety valve is also connected with the output end of the proppant filling, and the input end of the proppant filling is connected with the other output end of the separation tank.
7. The method for calculating the dynamic filtration coefficient of supercritical carbon dioxide fracturing fluid applied to the simulation device for calculating the dynamic filtration coefficient of supercritical carbon dioxide fracturing fluid according to any one of claims 1-6, characterized in that, The simulation device further comprises a fracturing fluid recovery system, the fracturing fluid recovery system comprises a separation tank, a refrigeration machine, a filter and a recovery tank, the input end of the separation tank is connected with the liquid outlet end of the filter loss instrument, one of the output ends of the separation tank is connected with the refrigeration machine, the filter and the recovery tank in sequence. The simulation device further comprises a fracturing fluid recovery system, the fracturing fluid recovery system comprises a separation tank, a refrigeration machine, a filter and a recovery tank, the input end of the separation tank is connected with the liquid outlet end of the filter loss instrument, one of the output ends of the separation tank is connected with the refrigeration machine, the filter and the recovery tank in sequence. The simulation device further comprises a fracturing fluid recovery system, the fracturing fluid recovery system comprises a separation tank, a refrigeration machine, a filter and a recovery tank, the input end of the separation tank is connected with the liquid outlet end of the filter loss instrument, one of the output ends of the separation tank is connected with the refrigeration machine, the filter and the recovery tank in sequence. The simulation device further comprises a fracturing fluid recovery system, the fracturing fluid recovery system comprises a separation tank, a refrigeration machine, a filter and a recovery tank, the input end of the separation tank is connected with the liquid outlet end of the filter loss instrument, one of the output ends of the separation tank is connected with the refrigeration machine, the filter and the recovery tank in sequence. The simulation device further comprises a fracturing fluid recovery system, the fracturing fluid recovery system comprises a separation tank, a refrigeration machine, a filter and a recovery tank, the input end of the separation tank is connected with the liquid outlet end of the filter loss instrument, one of the output ends of the separation tank is connected with the refrigeration machine, the filter and the recovery tank in sequence. The simulation device further comprises a fracturing fluid recovery system, the fracturing fluid recovery system comprises a separation tank, a refrigeration machine, a filter and a recovery tank, the input end of the separation tank is connected with the liquid outlet end of the filter loss instrument, one of the output ends of the separation tank is connected with the refrigeration machine, the filter and the recovery tank in sequence. The simulation device further comprises a fracturing fluid recovery system, the fracturing fluid recovery system comprises a separation tank, a refrigeration machine, a filter and a recovery tank, the input end of the separation tank is connected with the liquid outlet end of the filter loss instrument, one of the output ends of the separation tank is connected with the refrigeration machine, the filter and the recovery tank in sequence. The simulation device further comprises a fracturing fluid recovery system, the fracturing fluid recovery system comprises a separation tank, a refrigeration machine, a filter and a recovery tank, the input end of the separation tank is connected with the liquid outlet end of the filter loss instrument, one of the output ends of the separation tank is connected with the refrigeration machine, the filter and the recovery tank in sequence. The simulation device further comprises a fracturing fluid recovery system, the fracturing fluid recovery system comprises a separation tank, a refrigeration machine, a filter and a recovery tank, the input end of the separation tank is connected with the liquid outlet end of the filter loss instrument, one of the output ends of the separation tank is connected with the refrigeration machine, the filter and the recovery tank in sequence. The simulation device further comprises a fracturing fluid recovery system, the fracturing fluid recovery system comprises a separation tank, a refrigeration machine, a filter and a recovery tank, the input end of the separation tank is connected with the liquid outlet end of the filter loss instrument, one of the output ends of the separation tank is connected with the refrigeration machine, the filter and the recovery tank in sequence. The simulation device further comprises a fracturing fluid recovery system, the fracturing fluid recovery system comprises a separation tank, a refrigeration machine, a filter and a recovery tank, the input end of the separation tank is connected with the liquid outlet end of the filter loss instrument, one of the output ends of the separation tank is connected with the refrigeration machine, the filter and the recovery tank in sequence. The simulation device further comprises a fracturing fluid recovery system, the fracturing fluid recovery system comprises a separation tank, a refrigeration machine, a filter and a recovery tank, the input end of the separation tank is connected with the liquid outlet end of the filter loss instrument, one of the output ends of the separation tank is connected with the refrigeration machine, the filter and the recovery tank in sequence. The simulation device further comprises a fracturing fluid recovery system, the fracturing fluid recovery system comprises a separation tank, a refrigeration machine, a filter and a recovery tank, the input end of the separation tank is connected with the liquid outlet end of the filter loss instrument, one of the output ends of the separation tank is connected with the refrigeration machine, the filter and the recovery tank in sequence. The simulation device further comprises a fracturing fluid recovery system, the fracturing fluid recovery system comprises a separation tank, a refrigeration machine, a filter and a recovery tank, the input end of the separation tank is connected with the liquid outlet end of the filter loss instrument, one of the output ends of the separation tank is connected with the refrigeration machine, the filter and the recovery tank in sequence. The simulation device further comprises a fracturing fluid recovery system, the fracturing fluid recovery system comprises a separation tank, a refrigeration machine, a filter and a recovery tank, the input end of the separation tank is connected with the liquid outlet end of the filter loss instrument, one of the output ends of the separation tank is connected with the refrigeration machine, the filter and the recovery tank in sequence. The simulation device further comprises a fracturing fluid recovery system, the fracturing fluid recovery system comprises a separation tank, a refrigeration machine, a filter and a recovery tank, the input end of the separation tank is connected with the liquid outlet end of the filter loss instrument, one of the output ends of the separation tank is connected with the refrigeration machine, the filter and the recovery tank The fluid obtained after mixing is preheated by a temperature and pressure control system, and the preheated fluid is injected into the fluid loss instrument; The temperature and pressure of the core held by the core holder in the fluid loss instrument are regulated by the temperature and pressure control system, and the pressure difference between the front and rear ends of the fluid loss instrument is regulated by the back pressure pump and the nitrogen cylinder, and a plurality of filtration losses under different temperatures, different pressures, different pressure differences, different fracturing fluid viscosities and different core conditions are recorded; The experimental calculation parameters under the condition are calculated through the change curves of the filtration losses with time, and the dynamic filtration coefficient under the condition is calculated through the experimental calculation parameters.
8. The simulation method for calculating the dynamic filtration coefficient of supercritical carbon dioxide fracturing fluid of claim 7, characterized in that, The method further comprises: The dynamic filtration optimal coefficient is obtained, and the experimental parameters corresponding to the dynamic filtration optimal coefficient are obtained through inversion of the simulation device, the experimental parameters including temperature data, pressure data, pressure difference data, fracturing fluid viscosity data and core type data; The simulation device is run based on the experimental parameters, and preset proppants are added to the fluid loss instrument, and the dynamic filtration optimal coefficient is verified according to the sand production or sand plugging of the preset proppants.
9. The simulation method for calculating the dynamic filtration coefficient of supercritical carbon dioxide fracturing fluid of claim 7, characterized in that, The dynamic filtration coefficient under the condition is calculated through the experimental calculation parameters, specifically: In the formula, C represents the dynamic filtration coefficient, C1 represents the filtration coefficient affected by the fracturing fluid viscosity, C2 represents the filtration coefficient affected by the compressibility of the reservoir fluid, and C3 represents the filtration coefficient affected by the wall-building effect of the fracturing fluid.
10. The simulation method for calculating the dynamic filtration coefficient of supercritical carbon dioxide fracturing fluid of claim 9, wherein, The filtration coefficient affected by the fracturing fluid viscosity is specifically: wherein: wherein C1 represents the filtration coefficient affected by the viscosity of the fracturing fluid, K is the average permeability of the reservoir, φ is the original porosity of the reservoir, μ1 is the viscosity of the fracturing fluid, ΔP e represents the pressure difference inside and outside the fracture, P i represents the pressure at the perforation of the wellbore, P c represents the fracture closure pressure, t represents the initial time at which any node on the fracture opens, and T represents the total fracturing time; The filtration coefficient affected by the compressibility of the reservoir fluid is specifically: wherein: C t = S g C g + S w C w + C f ; where C2 represents the filtration coefficient affected by the compressibility of the reservoir fluid, K2 represents the average permeability of the reservoir, C t represents the overall compressibility of the reservoir, φ represents the original porosity of the reservoir, μ2 represents the viscosity of the fluid inside the reservoir, S g is the gas saturation of the reservoir, S w is the water saturation, C g is the gas compressibility of the reservoir, C w is the water compressibility, C f is the pore volume compressibility of the reservoir; The filtration coefficient affected by the wall-building effect of the fracturing fluid is specifically: wherein: where C3 represents the filtration coefficient under the effect of the wall-building action of the fracturing fluid, C 3e represents the filtration correction factor obtained from the experiment, ΔP e represents the pressure difference between the inside and outside of the fracture, ΔP c represents the stress difference in the experiment, A represents the cross-sectional area through which the filtration instrument flows, and m represents the experimentally calculated parameter.