CN114136861A

CN114136861A - Gas storage near-wellbore region drying salting-out effect experiment system and evaluation method

Info

Publication number: CN114136861A
Application number: CN202111435084.8A
Authority: CN
Inventors: 秦正山; 何勇明
Original assignee: Chengdu Univeristy of Technology
Current assignee: Chengdu Univeristy of Technology
Priority date: 2021-11-29
Filing date: 2021-11-29
Publication date: 2022-03-04
Anticipated expiration: 2041-11-29
Also published as: CN114136861B

Abstract

The invention provides a gas storage injection and production well near-wellbore region drying salting-out effect experimental system and an evaluation method. The experiment system consists of an injection system, a displacement system, a metering and waste gas treatment system and a computer processing system, can simulate the real injection and production process of the near-wellbore area of the gas storage, solves the problem that the conventional core indoor evaluation system cannot be applied to the evaluation of the drying salting-out effect of the near-wellbore area of the gas storage, and establishes a reservoir drying salting-out effect evaluation method. The invention establishes an anhydration salting-out effect evaluation method based on experiments, qualitatively and quantitatively combines to evaluate the salt blockage damage condition of the reservoir or the near-well stratum of the gas storage, deeply analyzes and recognizes the stratum damage problem caused by anhydration salting-out of the reservoir and an anhydration salting-out mechanism, guides and formulates corresponding treatment measures and schemes for eliminating or weakening salt blockage, and better solves the anhydration salting-out problem in the gas reservoir development and gas storage construction operation process.

Description

Gas storage near-wellbore region drying salting-out effect experiment system and evaluation method

Technical Field

The invention relates to the field of stratum damage evaluation of a near wellbore zone in the gas storage injection and production process, in particular to a gas storage injection and production well near wellbore zone drying salting-out effect experimental system and an evaluation method.

Background

During the production or storage of natural gas, conditions of contamination or formation damage of various types are often present in the near wellbore region. The stratum drying salting-out effect generated in the gas injection and production process of a gas storage is a type of reservoir pollution. In recent years, reservoir pollution caused by the dry salting-out effect is attracting attention.

Because the formation usually contains a certain amount of formation water, during the production of a gas well or the injection and production process of a gas storage, the produced gas or the injected and produced gas can cause the formation water existing in the pores of the reservoir to generate vaporization, and further cause the drying of the formation and the precipitation of salt precipitates in the pore spaces. The effective pore space of the stratum is reduced, the physical property is deteriorated, the blockage of a near-wellbore area is aggravated in the long-term gas well gas production process or the gas storage injection and production operation process, so that the pore permeability parameter is changed, and the productivity of the gas well or the injection and production capacity of the gas storage injection and production well is finally influenced. The indoor physical simulation experiment is an important basic means for revealing reservoir pollution mechanism and researching pollution on oil and gas reservoir development and gas reservoir building operation. Therefore, the experiment system and the evaluation method for the drying salting-out effect of the near-wellbore zone of the gas storage injection and production well have important guiding significance for the construction and operation of the gas storage.

At present, the field of stratum damage evaluation, a drying salting-out effect experimental system and an evaluation method for a near-wellbore zone of an injection and production well of a gas storage reservoir are in a technical blank at home, and the research of the field of drying salting-out is in a starting stage. The conventional indoor core evaluation system cannot meet the requirement of evaluation of the drying salting-out effect of the near-wellbore zone of the gas storage injection and production well. The main reasons are that: 1) the high-speed non-Darcy flow caused by the change of the flow velocity of the gas reservoir near the wellbore region cannot be simulated; 2) solute diffusion or migration caused by water intrusion cannot be simulated; 3) and the elimination or alleviation measures of salt blockage in the near wellbore region cannot be simulated.

Therefore, the establishment of an experiment system for evaluating the drying salting-out effect is the basis for the establishment of the corresponding evaluation method. The method is suitable for developing an experimental system for evaluating the drying salting-out effect of the near-wellbore region of the gas storage injection and production well, and establishing a corresponding stratum damage evaluation method, and has important significance for evaluating the damage condition of the reservoir stratum or the near-wellbore region of the gas storage, deeply knowing the drying salting-out mechanism, guiding to eliminate or weaken stratum blockage, improving the injection and production capacity of the gas storage injection and production well, and ensuring the stable operation of the gas storage.

Disclosure of Invention

In order to solve the problem that the conventional core indoor evaluation system cannot be applied to evaluation of the drying salting-out effect of the near-wellbore region of the injection and production well of the gas storage, the invention provides an experiment system and an evaluation method for the drying salting-out effect of the near-wellbore region of the gas storage.

In order to achieve the above object, the technical solution of the present invention is as follows.

An experiment system for a drying salting-out effect of a near wellbore zone of an injection and production well of a gas storage reservoir comprises an injection system, a displacement system, a metering and waste gas treatment system and a computer processing system, and comprises a conical steel sand filling cylinder, a screw pump, a gas cylinder, a displacement medium intermediate container and an observation window, wherein the gas cylinder is used for inputting gas and inputting the gas to the displacement medium intermediate container through a control valve, and the displacement medium intermediate container is connected with the conical steel sand filling cylinder; the screw pump, the gas cylinder and the displacement medium intermediate container form an injection system, the conical steel sand filling cylinder and the inlet and outlet observation window form a displacement system, the back pressure valve, the liquid metering device, the dryer, the gas metering device, the injected gas recovery device and the blow-down valve form a metering and waste gas treatment system, and the computer forms a computer processing system.

Simulating an injection and production process and a salt blockage eliminating process through a conical steel sand filling cylinder, wherein the conical steel sand filling cylinder is connected with an observation window, and fluid in and out of the conical steel sand filling cylinder is observed; the displacement medium intermediate container is connected with a screw pump, and fluid is injected through the screw pump.

The observation window comprises an inlet observation window and an outlet observation window, and the inlet fluid and the outlet fluid are observed respectively.

Further, the system comprises a back pressure valve, a liquid metering device, a gas metering device, a dryer, an injected gas recovery device and a computer, wherein the outlet end of the conical steel sand filling cylinder is connected with the back pressure valve and is sequentially connected with the liquid metering device, the dryer and the gas metering device, and metering data are transmitted to the computer.

The displacement medium intermediate container comprises an injected gas intermediate container, a clear water intermediate container and a brine intermediate container, wherein the injected gas intermediate container, the clear water intermediate container and the brine intermediate container are sequentially connected and are respectively connected with the gas cylinder and the screw pump through control valves.

The experimental process is divided into two parts, namely injection and production process simulation and salt blockage elimination process simulation. The concrete connection mode of the injection-production process simulation is as follows: firstly, a screw pump is connected with a control valve, an injected gas intermediate container, a clear water intermediate container and a saturated brine intermediate container are respectively connected, and the transmission of pressure and the entering of other pipeline fluids are controlled by the control valve between each intermediate container and the screw pump. The outlet end of each intermediate container is connected with a control valve, the outlet end of the gas cylinder is connected with a pressure meter and a control valve, and the gas cylinder and each intermediate container are converged on the same trunk line together and are regulated and controlled by the control valve at the trunk line. The control valve is branched into two paths, one line is connected with the inlet observation window, and the other line is connected with the outlet observation window; the two ends of the steel conical sand filling barrel and three positions inside the sand filling barrel are divided into three pressure measuring sections, each section is connected with a differential pressure gauge, and the middle position is connected with a temperature measuring meter for measuring pressure and temperature.

The steel conical sand filling cylinder comprises two end plugging covers, a conical steel inner cylinder, a cylindrical steel outer cylinder and a support frame, wherein the steel inner cylinder is of a conical structure so as to simulate the seepage characteristic of a stratum near a well zone; the steel outer barrel is cylindrical and is sleeved outside the steel inner barrel, and the steel inner barrel and the steel outer barrel are plugged by plugging covers at two ends.

The steel conical sand filling cylinder is divided into three pressure measuring sections between the inlet and the outlet, each section is connected with a differential pressure gauge, and the middle position is connected with a temperature gauge.

A gas storage injection-production well near-wellbore region drying salting-out effect evaluation method comprises a drying salting-out effect physical simulation experiment, a drying salting-out degree influence factor research method, a drying salting-out degree evaluation empirical formula and an analytical formula establishing thought and method, and specifically comprises the following steps:

s1, drying salting-out effect physical simulation experiment content and analysis method

S1.1, testing physical property parameters of simulated rock core

S1.11. porosity

Firstly, weighing net weight of an unfilled sand filling cylinder, then weighing dry weight of the sand filling cylinder after filling the sand filling cylinder to be compact, and assembling the sand filling cylinder into a displacement system. Injecting a prepared stratum water saturated rock core, stopping injection after saturation is finished, immediately cooling and relieving pressure, taking down and weighing the saturated simulated rock core to obtain the wet weight of the simulated rock core, and calculating to obtain the initial pore volume and porosity, namely

In the formula: v_pIs the pore volume, V_bTotal volume (or apparent volume), r₁Is a large section inner diameter r of a steel conical sand filling cylinder₂The inner diameter of the small section of the steel conical sand filling cylinder, L is the length of the simulated rock core (or the transverse distance of the steel conical sand filling cylinder), and m is_WetFor the wet weight of the sand-filling cylinder (including the weight of the sand-filling cylinder), m_{Dry matter}For the dry weight of the sand pack (including the weight of the sand pack), m_{Sand filling cylinder}For net weight of sand-packed cylinder, ρ_wIs the formation water density.

S1.12. permeability

The absolute permeability of rock is divided into liquid permeability and gas permeability according to the difference of injected media. The test was based on the following:

(1) liquid measured permeability

For a conical sand-filling cylinder, it is

Only the geometric dimension of the experimental simulated rock core is known

And (d) measuring the liquid property (mu) in the experiment, and calculating the absolute permeability K value of the rock by measuring the liquid flow (Q) and the pressure difference delta p corresponding to the flow Q at two ends of the rock core.

(2) Gas permeability

Gas permeability is measured by establishing a pressure difference between the two ends of a rock sample with pressurized gas, and measuring inlet and outlet pressures and outlet flow. Assuming that the seepage of gas in the core is a stable flow (which does not change with time), the weight flow of gas flowing through each section is constant, if the expansion process is an isothermal process:

in the formula, K_aFor gas permeability, Q is the flow through the mock core at differential pressure Δ p, Q₀At atmospheric pressure p_oVolume flow of lower gas, p_oTaking the pressure as atmospheric pressure, and taking the pressure of 0.1 MPa; p is a radical of₁And p₂L is the length of the simulated core (or the transverse distance of the steel conical sand filling cylinder) mu is the viscosity of the fluid passing through the simulated core,

the average cross section of the simulated rock core is shown as delta p, the pressure difference of fluid before and after passing through the simulated rock core is shown as delta p, and K is the absolute permeability of the rock core.

And (3) slip correction: in the experimental determination, the mean pressure was varied several times

Then calculating K according to a formula of a gas measurement method_aAnd draw K_aAnd

a relation curve; from formulas

It is seen that K_aAnd

is in a straight line with K_aThe intercept on the shaft is K_∞A value of and with K_∞As the absolute permeability of the rock.

S1.2 percolation test

The seepage experiment contents comprise an anhydration salting-out effect speed sensitivity experiment (a gas injection process speed sensitivity experiment and a gas production process speed sensitivity experiment), a water cut condition dry salting-out effect simulation experiment, a circulating injection-production process anhydration salting-out effect simulation experiment and an anhydration salting-out plugging-removal simulation experiment, and the specific experiment contents are as follows:

s1.21. experiment of speed sensitivity of drying salting-out effect

(1) Speed sensitivity test of gas injection process

1) First, the gas injection process is the reverse of the displacement system, i.e., injection from a small cross-section and outflow from a large cross-section. Adjusting the control valve to form a reverse displacement passage;

2) the displacement system is then warmed to the specified simulated temperature conditions. After the temperature is stable, injecting clear water into the simulated rock core to be fully saturated, and recording the saturated volume;

3) setting back pressure, respectively carrying out gas injection and water displacement experiments on the simulated rock core of the saturated water according to certain stepped gas injection speeds (generally from small to large, 0.5ml/h, 1ml/h, 1.5ml/h, 2ml/h and 2.5ml/h), and testing pore seepage parameters in an initial state. And (4) recording displacement time, pump reading, injection pressure, injection speed, back pressure, differential pressure meter reading and thermometer reading at each position, metering air quantity and water quantity and the like in the experimental process. The above steps were used as a salt-free displacement control group for the experiment;

4) and after the displacement is finished, vacuumizing and restoring the simulated rock core, displacing the simulated rock core by using saturated brine and recording the saturation volume when the system is restored to the specified temperature condition. Respectively carrying out gas injection flooding saturated brine experiments on the simulated rock core of the saturated brine at a certain stepped gas injection speed (the speed is the same as that of a salt-free control group), and recording related experimental data;

5) and after the experiment of gas injection displacement saturated brine is completed, testing the gas logging permeability of the simulated rock core. And after the test is finished, performing reverse unblocking (the displacement system still keeps reverse connection) by using the clear water to displace the rock core so as to restore the initial state of the simulated rock core. And monitoring the water mineralization degree of the outflow end, recording related experimental data in the plugging process when the water mineralization degree is 0 and considering that the plugging removal is finished, testing the pore permeability parameters after the plugging removal, and evaluating the injection capacity change of the simulated rock core and the recovery condition of the pore permeability parameters.

(2) Speed sensitivity test of gas production process

1) The gas production process is the positive process of the displacement system (injection from a large section and outflow from a small section). Adjusting the control valve to form a positive displacement path;

2) the displacement system is warmed to the specified simulated temperature conditions. After the temperature is stable, injecting saturated brine into the simulated rock core to be fully saturated, and recording the saturated volume;

3) respectively carrying out gas injection and brine displacement experiments on a simulated core of saturated brine according to a certain stepped gas injection speed (the injection needs to be carried out from small to large at a small flow rate, namely 0.1ml/h, 0.2ml/h, 0.3ml/h, 0.4ml/h and 0.5ml/h), establishing the saturation of the bound water, and recording related experimental data (generally, an oil displacement method is adopted for establishing the saturation of the bound water, but in order to avoid the problem of influence of crude oil on the properties of the simulated core, low-speed gas injection can be adopted so as to avoid serious gas channeling. Secondly, low-speed rising-speed gas injection is adopted, so that severe gas channeling is avoided, and the gas drive front edge is pushed slowly. For low permeability cores, the method has better applicability).

4) Setting back pressure, injecting the simulated rock core under the bound water according to certain step gas injection speeds (generally from small to large, 0.5ml/h, 1ml/h, 1.5ml/h, 2ml/h and 2.5ml/h) to simulate the gas production process, and recording related experimental data in the experimental process. Testing the gas logging permeability of the simulated rock core after the simulation of the gas production process is finished;

5) and after the test is finished, performing reverse blocking removal treatment (reverse connection of a displacement system) by using the clear water displacement rock core, recording relevant experimental data in the blocking process, testing the pore permeability parameter after blocking removal, and evaluating the injection capacity change of the simulated rock core and the recovery condition of the pore permeability parameter.

In the experimental process, the injection medium adopted in the saturated simulation of the rock core is saturated brine, and the gas displacement water experiment with different mineralization degrees at a constant gas injection speed can be carried out to research the influence of the mineralization degree of the formation water on the drying salting-out effect of the reservoir.

S1.22. simulation experiment of dry salting-out effect under water-invasion condition

(1) Important parameters

For gas-water two-phase displacement, several important parameters are involved as follows:

1) phase (or effective) permeability

The phase permeability refers to the phase permeability or effective permeability of a multiphase fluid when the multiphase fluid coexists and flows, wherein the capacity of the multiphase fluid to pass through the rock is the same. The effective (phase) permeability of each phase of gas and water can be respectively recorded as K_g、K_w。

2) Relative permeability

The relative permeability of a phase fluid is the ratio of the effective permeability to the absolute permeability of the phase fluid and is a direct measure of the amount of fluid that passes through the rock.

The relative permeability of the gas and water is respectively recorded as:

(2) air water relative permeability experimental test

And simulating a water invasion condition according to a gas-water relative permeability experiment testing principle. The test of the relative permeability is divided into a steady-state method and an unsteady-state method, and specific experimental steps can be formulated according to the current recommended standard of GB/T28912-2012 method for determining the relative permeability of the two-phase fluid in rock.

During testing, polluted and uncontaminated simulated cores can be respectively adopted to carry out gas-water co-injection to simulate the invasion of water in the gas production process (the uncontaminated simulated core is selected to eliminate salting-out pollution in the prior art and evaluate the salt blockage condition of the simulated core after the water invasion, and the polluted simulated core is selected to study the influence of the water invasion on the original blockage condition).

After the relative permeability of a certain injection proportion is tested by the gas-water co-injection, the absolute permeability of the simulated rock core needs to be tested. And after the test is finished, performing reverse blocking removal treatment (reverse connection of a displacement system) by using the clear water displacement rock core, recording relevant experimental data in the blocking process, testing the pore permeability parameter after blocking removal, and evaluating the injection capacity change of the simulated rock core and the recovery condition of the pore permeability parameter.

S1.23. simulation experiment of drying salting-out effect in circulating injection-production process

1) Simulating a first circulation gas injection process of a circulation injection and production process, specifically injecting from a small section and flowing out from a large section, and adjusting a control valve to form a reverse displacement passage;

3) carrying out gas injection brine flooding experiment on the simulated rock core of saturated brine at a constant gas injection speed, and testing the gas logging permeability of the simulated rock core after the pressure and flow at the inlet and outlet ends are stable;

4) the injection and production direction is adjusted, saturated brine and injected gas are injected from a large section at the same time, and the saturated brine flows out from a small section to simulate the gas production process (the gas-water ratio is set to be 20: 1) and after the experimental temperature and pressure are stable, testing the gas logging permeability of the simulated rock core. Repeating the steps to simulate the cyclic injection and production process;

5) and (4) recording displacement time, pump reading, injection pressure, injection speed, back pressure, differential pressure meter reading and thermometer reading at each position, metering air quantity and water quantity and the like in the experimental process. And after the simulation experiment of the circulating injection and production process is completed, performing reverse blocking removal treatment (reverse connection of a displacement system) by using a clear water displacement rock core, recording related experimental data in the blocking removal process, and testing the pore permeability parameters after blocking removal.

The above process is a simulation of the circulating injection and production process under the consideration of water intrusion, and the saturated brine and the injected gas can be injected only to simulate the gas production process without injecting the saturated brine and the injected gas together, and the saturated brine and the injected gas are used as a control group of the circulating injection and production process under the condition of no water intrusion.

S1.24. simulation experiment for drying salting-out and blockage removal

By reversely injecting clear water from the simulated rock core for unblocking (small-section injection and large-section outflow), physical property parameters of the simulated rock core before and after unblocking are tested, pressure data of each section of the displacement system are recorded, and the injection capacity and the variation of the pore permeability parameters of the simulated rock core before and after unblocking are evaluated.

Secondly, from the viewpoint of economic and efficient blockage removal, the blockage removal injection agent is generally selected from clear water.

S2 reservoir drying salting-out effect evaluation method

The reasons for the generation of the reservoir drying salting-out effect and the influencing factors of the salting-out degree are manifold. In the process of natural gas injection and production, salt precipitation in pores can cause the effective pore space to be reduced, the permeability to be poor and the seepage resistance of fluid to be increased. The deformation of the pore space and the change in the fluid are described and are usually characterized by the ratio of the initial and current physical parameters (or the degree of change in the physical parameters). The following were used:

or

Where P is formation pressure, T is formation temperature, ω is mineralization, S_wiIs the initial average water saturation, S_wIs the current average water saturation, v_inIs the gas injection velocity, v_outIs gas production rate, r_eIs the radius of gas supply, E is the energy of the water body, and s is the epidermal factor.

Based on a statistical analysis method and a multiple nonlinear regression (or based on a neural network principle), determining main influence factors of the physical property parameter change degree, and establishing a corresponding empirical formula.

The empirical formula is subjected to error detection, and then the method can be applied to evaluation of the drying salting-out degree of the on-site conventional gas well and the gas injection and production gas well of the gas storage.

Based on the evaluation result, corresponding evaluation standards can be established for guiding gas reservoir development and gas storage bank building operation.

The invention has the beneficial effects that:

1. the improved simulated core, namely the steel conical sand filling barrel of the embodiment of the invention can simulate the high-speed Darcy effect caused by the reduction of the seepage sectional area in the near-wellbore area of the gas storage injection and production well, and establishes the necessary conditions for experimental research on the drying salting-out effect in the near-wellbore area in the gas storage injection and production process. The structure of the displacement system is beneficial to evaluating the salting-out degrees of different positions and guiding to make corresponding blockage removal measures and schemes;

2. the experiment system established by the invention is beneficial to solving the problem that the conventional rock core indoor evaluation system cannot be applied to evaluation of the drying salting-out effect of the near-wellbore zone of the gas storage injection and production well. By utilizing the experimental system provided by the embodiment of the invention, a foundation is laid for the research of the drying salting-out effect mechanism, and an important data body is provided for the evaluation of the drying salting-out effect;

3. the invention establishes a systematic evaluation idea and method of the drying salting-out effect of the near-wellbore region of the gas storage injection well, combines qualitative analysis and quantitative analysis to evaluate the damage condition of the near-wellbore stratum of the gas storage, provides powerful guarantee and solutions for deeply analyzing and recognizing the stratum damage problem caused by drying salting-out of the stratum and the drying salting-out mechanism, and guides related practitioners to make corresponding treatment measures and schemes for eliminating or weakening salt blockage.

Drawings

FIG. 1 is a diagram showing the configuration of an experimental system in which the present invention is implemented.

FIG. 2 is a schematic diagram of an experimental procedure implemented by the present invention.

Fig. 3 is a schematic structural diagram of a displacement system implemented by the present invention.

Fig. 4 is an assembly view of a displacement system implemented in accordance with the present invention.

FIG. 5 is a schematic diagram of a reservoir drying salting-out effect evaluation technique implemented by the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

The basic basis and principle established by the experimental system of the embodiment of the invention are as follows:

firstly, as the gas flows into the well, the flow cross section vertical to the flow direction is smaller close to the well axis, the seepage velocity is increased rapidly, the pressure drop funnel is steeper than the linear seepage, the high-speed flow around the well axis is equivalent to the turbulent flow, namely, the seepage in the near-well area of the gas reservoir has the high-speed non-Darcy effect. By utilizing the conventional core holder, fluid is approximately regarded as one-dimensional unidirectional flow through the cylindrical core, the seepage sectional areas at different positions are the same, the actual seepage sectional area of the near-wellbore zone is reduced along with the distance close to the well shaft, the seepage speed is maximum near the wellbore, and the cylindrical core obviously cannot simulate the characteristic that the seepage sectional area changes along with the position. In the gas injection and production process, the quantity of salt precipitates or the serious salt blockage position at the position is determined by the characteristic that the seepage velocity changes along with the position. In addition to flow rate variation being related to pressure drop, the high velocity non-darcy effect near the wellbore is one of the main causes of flow rate variation. Although, inertial (or turbulent) effects are prevalent when laboratory gas measurements are made on highly permeable cores. The reason for this is not only the size of the percolation resistance (or permeability, viscosity), but also the relatively high flow rate (or the difficulty of measurement if a low pressure gradient is required for a low volume flow rate) for the metering requirements. However, for displacement experiments, the flow rate variation caused by pressure drop has strong randomness (microscopic heterogeneity determination), and the relationship between the salt deposition amount and the position is difficult to characterize. Therefore, it is desirable and necessary to create an improved pseudocore to simulate high velocity seepage in the near wellbore region of a gas reservoir. Just as the steel conical sand filling barrel with dynamic pressure measurement monitoring provided by the embodiment of the invention is convenient for solving the problems or difficulties;

secondly, for a gas reservoir with active water, the gas reservoir water invasion phenomenon is ubiquitous due to the plane and longitudinal heterogeneity of the reservoir. Gas reservoir water invasion can cause water to accumulate in the well bore of the gas well, affecting gas well production. The reservoir drying salting-out effect and gas reservoir water invasion exist simultaneously, and the gas reservoir water invasion can accelerate the diffusion or migration of solutes in the reservoir. Therefore, simulating the solute diffusion or migration phenomenon caused by water intrusion is very important for evaluating the dynamic process of reservoir drying salting-out;

and thirdly, simulating the treatment measures of the salt blockage of the near-wellbore region of the reservoir, having important guiding significance for formulating a solution of the salt blockage and eliminating or weakening the near-wellbore blockage, and providing technical support for better solving the problems of drying and salting out in the processes of gas reservoir development and gas storage construction operation.

Based on this, the experimental system of the embodiment of the present invention (fig. 1 and fig. 2 show the schematic diagram of the experiment system of the drying salting-out effect in the near wellbore region of the gas storage injection and production well and the composition diagrams of each system of the experiment system of the embodiment of the present invention) mainly comprises a conical steel sand filling barrel 1, a screw pump 2, a gas cylinder 3, a displacement medium intermediate container (including an injected gas intermediate container 5, a clean water intermediate container 6, and a saturated brine intermediate container 7), an inlet and outlet observation window 8 (including observation windows 1 and 2), a back pressure valve 4, a liquid metering device 9, a dryer 10, a gas metering device 11, an injected gas recovery device 12, and a computer 13.

A displacement medium intermediate container (comprising an injected gas intermediate container 5, a clear water intermediate container 6 and a saturated brine intermediate container 7) and an inlet and outlet observation window 8 are placed in an air bath oven; the data collected by the liquid measuring device 9 and the gas measuring device 11 are input to a computer for processing. The displacement medium intermediate containers (injection gas intermediate container 6, clear water intermediate container 7, brine intermediate container 8) and the displacement system were in an air bath oven to simulate specific reservoir temperature conditions (fig. 1, 2).

The experiment system consists of four parts, namely an injection system, a displacement system, a metering and waste gas treatment system and a computer processing system. Wherein, the screw pump 2, the gas cylinder 3, the displacement medium intermediate container (including the injected gas intermediate container 5, the clear water intermediate container 6, the saturated brine intermediate container 7) and the related control valve constitute the injection system, the conical steel sand filling barrel 1 and the inlet and outlet observation window 8 (including the observation windows 1 and 2) constitute the displacement system, the back pressure valve 4, the liquid metering device 9, the dryer 10, the gas metering device 11 and the injected gas recovery unit 12, the blow-down valve constitutes the metering and waste gas treatment system, and the computer 13 constitutes the computer processing system.

The experimental process is divided into two parts, namely injection and production process simulation and salt blockage elimination process simulation. The concrete connection mode of the injection-production process simulation is as follows: firstly, a screw pump 2 is connected with a control valve 1, an injected gas intermediate container 5, a clear water intermediate container 6 and a saturated brine intermediate container 7 are respectively connected, and pressure transmission and other pipeline fluids entering are controlled between each intermediate container and the screw pump 2 through the control valve 2, the control valve 3 and the control valve 4. The outlet end of each intermediate container is connected with a control valve 6, a control valve 7 and a control valve 8, the outlet end of the gas cylinder 3 is connected with a pressure meter and a control valve 5, the pressure meter and the control valve are converged on the same trunk line together, and the control valve 9 is used for regulating and controlling the trunk line. The control valve 9 is divided into two paths, one line is connected with the control valve 10, the observation window 1, two ends of the steel conical sand filling cylinder 1 and the observation window 2, the space between the inlet and the outlet of the sand filling cylinder 1 is divided into three pressure measuring sections, each section is connected with a differential pressure gauge (the differential pressure gauges 1, 2 and 3 are respectively used for measuring, and the differential pressure gauges 1, 2 and 3 are respectively used for measuring), and the middle position is connected with a temperature gauge.

The outlet end of the displacement system is connected with a back pressure valve, and is sequentially connected with a liquid metering device 9, a dryer 10 and a gas metering device 11, metering data is transmitted to a computer, and the back of the gas metering device is connected with an emptying valve, a control valve 11 and a recovery dissolving container of injected gas (figure 1 and figure 2).

In order to simulate the stratum near the well end plugging removal process, injection media need to be injected from the outlet end of the conical steel sand filling cylinder 1, flow out from the inlet end, and are metered and recovered. The specific connection mode of the salt blockage eliminating process is as follows: at the control valve 9, two branch lines are divided, one branch line enters the large-section-area inlet of the steel sand filling cylinder along the injection process (forward direction) (when in reverse displacement, the control valve 10 is closed), and the other branch line enters the small-section-area inlet of the steel conical sand filling cylinder 1 along the salt blockage eliminating process (reverse direction) (dotted line in figure 1). After the small section flows in, the small section is connected with the observation window 2, the displacement system (namely the conical steel sand filling cylinder 1) and the observation window 1 and is divided into two branch lines. One of which is connected to the control valve 10 (control valve 10 closed in the case of reverse displacement), and the other of which is connected to the metering system via the control valve 12 (dashed line in fig. 1). In addition, after the control valve 7 at the outlet end of the clear water intermediate container is connected with the control valve 13, the clear water intermediate container is connected with the brine intermediate container 7 and used for auxiliary blending of brine. The displacement medium intermediate containers (injection gas intermediate container 5, clear water intermediate container 6, brine intermediate container 7) and the displacement system were in an air bath oven to simulate specific reservoir temperature conditions (fig. 1, fig. 2).

The structure of the steel conical sand filling barrel 1 comprises two end plugging covers 11, a conical steel inner barrel 13, a cylindrical steel outer barrel 12 and a support frame 14, wherein the steel conical sand filling barrel 1 is further provided with a plurality of pressure measuring heads, a middle temperature measuring head (a pressure measuring column and a temperature measuring injection are communicated with the wall surface of the conical steel inner barrel), differential pressure gauges 1, 2 and 3 (as shown in figures 3 and 4, the differential pressure gauges 1, 2 and 3 measure the pressure of the steel conical sand filling barrel in a segmented manner). Designing the size: the length of the core barrel is 1.06 m (the effective length of the simulated core is 1m, the length of the internal thread at two ends of the conical barrel is 3cm, the wall thickness of the internal thread is 0.5cm), the radius R of the large section is 10cm, and the radius R of the small section is 0.25R. The outer diameter of the cylindrical steel outer cylinder is 15cm, and the wall thickness of the outer cylinder is 0.5cm (figures 3 and 4). The steel inner cylinder 13 is of a conical structure so as to simulate the seepage characteristics of the near wellbore zone of the stratum; the steel outer cylinder 12 is cylindrical and is sleeved outside the steel inner cylinder 13, and the steel inner cylinder 13 and the steel outer cylinder 12 are plugged by plugging covers 11 at two ends.

The invention discloses a method for evaluating the drying salting-out effect of a near-wellbore zone of an injection well of a gas storage, which comprises a physical simulation experiment of the drying salting-out effect, a method for researching factors influencing drying salting-out degree, an empirical formula for evaluating the drying salting-out degree and a method for analyzing the formula, and comprises the following steps of:

(I) preparation of test samples

1. Sand for sand filling cylinder: usually, quartz sand or refined ceramic sand grains are selected.

2. The sand consumption is as follows: the sand with different particle sizes is screened and densely filled according to a certain proportion, and the filling method can refer to the patent CN107742031A granted by the inventor to simulate the reservoir conditions under the requirement of specific physical property parameters.

3. Injecting a medium: mainly comprises nitrogen or methane (carbon dioxide, hydrogen and the like can be considered under special conditions, such as simulation of damage conditions near a well during underground storage of the carbon dioxide or the hydrogen), clean water or distilled water, and saturated or unsaturated brine.

(II) measurement of geometrical and physical parameters of sample

And measuring the weight of the packed gravel, the geometric dimension of the steel conical plunger, the mineralization degree of saturated brine and the like.

(III) test system connection, assembly and tightness detection

And connecting and assembling all components of the experiment system, including an injection system, a displacement system, a metering and waste gas treatment system and a computer processing system. The tightness of the respective system was checked by monitoring the pressure.

(IV) formation temperature and pressure simulation

The air bath oven temperature is set to the actual formation temperature condition. Compared with a cemented rock core, sand grains in the sand filling cylinder are easy to generate pore deformation under the confining pressure effect, and the confining pressure is repeatedly loaded and unloaded, so that the experimental result is not contrastive due to the pore deformation, and the simulated formation pressure condition is temporarily not considered.

(V) physical property parameter test of simulated rock core

1. Porosity of

Porosity reflects the degree of development of pores in the rock, characterizing the ability of a reservoir to store fluids. The testing method generally adopts a weighing method.

2. Permeability rate of penetration

(1) liquid measured permeability

Based on Darcy's formula

Namely, it is

For a conical sand-filling cylinder, can be written as

Therefore, only the geometric dimension of the experimental simulated core is known

(2) Gas permeability

The theoretical basis of permeability gas measurement is still Darcy's law, and the concrete method is to use pressurized gas (nitrogen cylinder or forced draught fan) to establish pressure difference at two ends of rock sample, and measure inlet and outlet pressure and outlet flow.

For the tapered simulated core of the example of the invention, the seepage of gas in the core is assumed to be a stable flow (which does not change along with time), so the weight flow of gas flowing through each section is constant. If the expansion process is an isothermal process, according to the Boyle-Mariotte law:

Qp＝Q_op_ois constant or

In the formula, Q_oAt atmospheric pressure p_oVolumetric flow rate of the lower gas.

Thus, it is possible to provide

Separate the variables, integrate over both sides, then

To obtain

Is transformed to obtain

In the formula, K_aFor gas permeability, Q is the flow through the mock core at differential pressure Δ p, Q₀At atmospheric pressure p_oVolume flow of lower gas, p_oTaking the pressure as atmospheric pressure, and taking the pressure of 0.1 MPa; p is a radical of₁And p₂Is the absolute pressure at the inlet and outlet cross-sections, L is the mock core length (or lateral distance of the steel conical sand pack), μ is the fluid viscosity through the mock core,

And (3) slip correction: and correcting by using a plate. In particular, the average pressure is changed for several times during experimental determination

a relationship curve. Slave maleFormula (II)

It is seen that K_aAnd

(VI) seepage test

The seepage experiment contents comprise an anhydration salting-out effect speed sensitivity experiment (a gas injection process speed sensitivity experiment and a gas production process speed sensitivity experiment), a water cut condition dry salting-out effect simulation experiment, a circulating injection-production process anhydration salting-out effect simulation experiment and an anhydration salting-out unblocking simulation experiment. The specific experimental contents are as follows:

1. speed sensitivity experiment of drying salting-out effect

(1) Speed sensitivity test of gas injection process

2) the displacement system is then warmed to the specified simulated temperature conditions. After the temperature is stable, injecting clear water into the simulated rock core for full saturation (the saturation time is determined by the difference value between the saturation volume and the pore volume), and recording the saturation volume;

(2) Speed sensitivity test of gas production process

2. Simulation experiment of dry salting-out effect under water-cut condition

(1) Important parameters

1) phase (or effective) permeability

2) Relative permeability

The relative permeability of the gas and water is respectively recorded as:

(2) air water relative permeability experimental test

3. Simulation experiment for drying salting-out effect in circulating injection-production process

4. Simulation experiment for drying salting-out and unblocking

Second, reservoir drying salting-out effect evaluation method

Evaluation method establishment basis and evaluation thought

An anhydration salting-out effect physical simulation experiment is the basis for establishing a reservoir anhydration salting-out effect evaluation method. Not only provides a data body for research, but also is the most direct and objective research means for explaining the drying salting-out mechanism.

The reasons for the generation of the reservoir drying salting-out effect and the influencing factors of the salting-out degree are manifold. In the process of natural gas injection and production, salt precipitation in pores can cause the effective pore space to be reduced, the permeability to be poor and the seepage resistance of fluid to be increased. The deformation of the pore space and the change of the fluid are described, and are generally characterized by the ratio of the initial physical parameters to the current physical parameters (or the change degree of the physical parameters). The following were used:

or

The change in porosity, permeability, is two important parameters characterizing the degree of salting out. The influencing factors of the two parameters are multivariate, such as formation pressure P, formation temperature T, degree of mineralization omega, water saturation (initial average water saturation S)_wiAnd the current average water saturation S_w) Gas injection velocity v_inGas production velocity v_outRadius of gas supply r_eWater body energy E, epidermal factor s and the like.

Obviously, each factor and each research target parameter belong to an integral system, and it is difficult to establish an analytical equation containing all the influencing factors. For the grey problem of the complex system, a statistical analysis method is adopted from the concept of the whole according to indoor experiments, numerical simulation, field actual measurement, various dynamic and static data, interpretation result data and the like, the relationship between each factor data and the parameter of a research target and the strength of the influence degree are mined, and a foundation can be laid for establishing the introduction of drying salting-out degree evaluation empirical model formula parameters. Based on the research result of the influence factors of the statistical analysis, the method can also provide reference for establishing a reservoir drying salting-out evaluation analysis model in the later period.

Secondly, in a complex system, each influence factor and a research target parameter have a highly complex nonlinear relation, and the drying degree evaluation empirical formula based on the multiple nonlinear regression can be established to effectively solve the problems. The empirical formula is subjected to error detection, and then the method can be applied to evaluation of the drying salting-out degree of the on-site conventional gas well and the gas injection and production gas well of the gas storage. And establishing corresponding evaluation standards based on the evaluation results to guide gas reservoir development and gas reservoir building operation.

It should be noted that: firstly, when the relation between each factor and the research target parameter is researched by adopting a statistical analysis method, the selection of the statistical analysis method is not unique and needs to be selected according to the characteristics of data. The invention provides a statistical analysis method suitable for research of influence factors of the drying salting-out degree, such as a grey correlation method, principal component analysis, an entropy weight method and a stepwise regression method. The gray correlation method is widely applied to the gray problem (the influence degree of various factors and a research target) in a complex research system, and the calculated gray correlation degree can quantitatively evaluate the influence degree of each factor and the research target and guide the elimination of non-sensitive factors. Besides the gray correlation method, both principal component analysis and entropy weight method can solve the correlation research problem (shown in fig. 5, dotted line) between the influencing factors and the research targets under specific data and scenes. Secondly, the main influence factor for determining the drying salting-out degree is the basis for establishing a model and is related to the introduction of empirical formula parameters. Since the stepwise regression method has the characteristic of parameter screening, the screening standard is measured by the error. Therefore, the corresponding empirical model can be established by directly adopting the stepwise regression method without separately researching the main influencing factors influencing the target parameters (fig. 5, dotted line part).

Thirdly, an empirical formula can be established for practical application scenarios, but the obvious disadvantage is that deep physical and functional relationships among physical quantities cannot be revealed, which is unfavorable for theoretical understanding of the drying salting-out rule or mechanism. Therefore, establishing an analysis formula for evaluating the drying salting-out degree is a necessary condition for deeply researching the drying salting-out mechanism, and is also a basis for establishing selection of an empirical formula equation form. Whether empirical formulas are established or analytical models are developed, they have complementary relationships to each other. The empirical formula can provide guidance and thinking for introducing main parameters for establishing the analytical formula, and the establishment of the theoretical analytical formula can also provide guidance (such as an equation form and parameter introduction) for better establishing an empirical model with high prediction precision.

Finally, for the prediction problem of the research target in which the functional relation or the physical relation between the target parameters and the influencing factors in each system is difficult to establish by using an accurate analytical formula in a complex system, the establishment of an empirical formula based on a statistical analysis method and multiple nonlinear regression has good practical value. With regard to the establishment of the empirical formula, it should be noted that: the empirical formula can be characterized by adopting a formula form with clear relationship among parameters, and can also be characterized by establishing a neural network model based on artificial intelligence principle and data characteristics (figure 5, dotted line part). Each method has its own application scenario and data requirements. For the prediction data conditions with a large amount of experiments, production data, dynamic and static data interpretation results and the like, the neural network model is well adapted to the establishment of the neural network model, the application range and the prediction precision are relatively higher, and the establishment of the empirical formula represented in the formula form is more suitable for the specific application scene with limited data.

The present invention is not limited to the above preferred embodiments, and any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An experiment system for a drying salting-out effect of a near wellbore zone of an injection and production well of a gas storage reservoir comprises an injection system, a displacement system, a metering and waste gas treatment system and a computer processing system, and comprises a conical steel sand filling cylinder, a screw pump, a gas cylinder, a displacement medium intermediate container and an observation window, wherein the gas cylinder is used for inputting gas and inputting the gas to the displacement medium intermediate container through a control valve, and the displacement medium intermediate container is connected with the conical steel sand filling cylinder; wherein, the screw pump, the gas cylinder and the displacement medium intermediate container form an injection system, the conical steel sand filling cylinder and the inlet and outlet observation window form a displacement system, the back pressure valve, the liquid metering device, the dryer, the gas metering device, the injected gas recovery device and the blow-down valve form a metering and waste gas treatment system, and the computer forms a computer processing system; simulating an injection and production process and a salt blockage eliminating process through a conical steel sand filling cylinder, wherein the conical steel sand filling cylinder is connected with an observation window, and fluid in and out of the conical steel sand filling cylinder is observed; the displacement medium intermediate container is also connected with a screw pump, and fluid is injected through the screw pump.

2. The gas reservoir near-wellbore region drying salting-out effect experimental system of claim 1, wherein the observation window comprises an inlet observation window and an outlet observation window for observing inlet and outlet fluid respectively.

3. The experiment system for the drying salting-out effect in the near wellbore area of the gas storage reservoir as claimed in claim 1, wherein the system comprises a back pressure valve, a liquid metering device, a gas metering device, a dryer, an injected gas recovery device and a computer, wherein the outlet end of the conical steel sand filling cylinder is connected with the back pressure valve, and is sequentially connected with the liquid metering device, the dryer and the gas metering device, and the metering data are transmitted to the computer.

4. The gas storage near-wellbore region drying salting-out effect experimental system of claim 1, wherein the displacement medium intermediate container comprises an injected gas intermediate container, a clear water intermediate container and a brine intermediate container, and the injected gas intermediate container, the clear water intermediate container and the brine intermediate container are sequentially connected and respectively connected to the gas cylinder and the screw pump through control valves.

5. The experiment system for the drying salting-out effect of the near wellbore area of the gas storage as claimed in claim 1, wherein the steel conical sand filling barrel comprises two end plugs, a conical steel inner barrel, a cylindrical steel outer barrel and a support frame, and the steel inner barrel is of a conical structure to simulate a rock core; the steel outer barrel is cylindrical and is sleeved outside the steel inner barrel, and the steel inner barrel and the steel outer barrel are plugged by plugging covers at two ends.

6. The gas storage near-wellbore region drying salting-out effect experimental system of claim 5, wherein the inlet and outlet positions of the steel conical sand filling barrel are divided into three pressure measuring sections, each section is connected with a differential pressure gauge, and the middle position is connected with a temperature gauge.

7. A method for evaluating the drying salting-out effect of a near wellbore zone of an injection and production well of a gas storage reservoir is characterized in that the method utilizes the system of claim 1 and comprises the following specific steps:

S1.1, testing physical property parameters of simulated rock core

S1.11. porosity

Firstly weighing an unfilled conical steel sand filling cylinder, then filling the conical steel sand filling cylinder to be compact, weighing the conical steel sand filling cylinder to be dry, assembling, injecting a prepared formation water saturated core, stopping injection after saturation is finished, immediately cooling and relieving pressure, taking down and weighing a saturated simulated core to obtain the wet weight of the simulated core, and calculating to obtain the initial pore volume and porosity, namely

In the formula: v_pIs the pore volume, V_bIs the total volume, r₁Is a large section inner diameter r of a steel conical sand filling cylinder₂The inner diameter of the small section of the steel conical sand filling cylinder, L is the length of the simulated rock core (or the transverse distance of the steel conical sand filling cylinder), and m is_WetFor the wet weight of the sand-filling cylinder (including the weight of the sand-filling cylinder), m_{Dry matter}M is dry weight of sand filling cylinder_{Sand filling cylinder}For net weight of sand-packed cylinder, ρ_wIs the formation water density.

S1.12. permeability

The absolute permeability of rock is divided into liquid permeability and gas permeability according to the difference of injected media, and the test is based on the following:

(1) liquid measured permeability

For a conical sand-filling cylinder, it is

Only the geometric dimension of the experimental simulated rock core is known

(2) Gas permeability

Gas permeability measurement is to establish pressure difference at two ends of a rock sample by using pressurized gas, and measure inlet and outlet pressures and outlet flow; assuming that the seepage of gas in the core is a stable flow, the weight flow of the gas flowing through each section is constant, and if the expansion process is an isothermal process:

S1.2 percolation test

The seepage experiment contents comprise an anhydration salting-out effect speed sensitivity experiment, an anhydration salting-out effect simulation experiment under a water invasion condition, an anhydration salting-out effect simulation experiment in a circulating injection-production process and an anhydration salting-out blockage removal simulation experiment, and the specific experiment contents are as follows:

s1.21. experiment of speed sensitivity of drying salting-out effect

(1) Speed sensitivity test of gas injection process

1) Firstly, the gas injection process is the reverse process of the displacement system, namely, the gas is injected from a small section and flows out from a large section; adjusting the control valve to form a reverse displacement passage;

2) then, heating the displacement system to a specified simulated temperature condition; after the temperature is stable, injecting clear water into the simulated rock core to be fully saturated, and recording the saturated volume;

3) setting back pressure, respectively carrying out gas injection and water flooding experiments on the simulated rock core of the saturated water according to a certain stepped gas injection speed, and testing pore permeability parameters in an initial state;

4) after the displacement is finished, vacuumizing and restoring the simulated rock core, displacing the simulated rock core by using saturated brine when the system is restored to a specified temperature condition, and recording the saturated volume; respectively carrying out gas injection flooding saturated brine experiments on the simulated rock core of the saturated brine according to a certain stepped gas injection speed, and recording related experimental data;

5) after the experiment of gas injection displacement saturated brine is finished, testing the gas logging permeability of the simulated rock core; after the test is finished, the core is displaced by clear water for reverse unblocking so as to restore the initial state of the simulated core; and monitoring the water mineralization degree of the outflow end, considering that the plugging removal is finished when the water mineralization degree is 0, recording relevant experimental data in the plugging removal process, testing pore permeability parameters after the plugging removal, and evaluating the injection capacity change of the simulated rock core and the recovery condition of the pore permeability parameters.

(2) Speed sensitivity test of gas production process

1) The gas production process is a positive process of the displacement system, and a control valve is adjusted to form a positive displacement passage;

2) heating the displacement system to a specified simulated temperature condition; after the temperature is stable, injecting saturated brine into the simulated rock core to be fully saturated, and recording the saturated volume;

3) respectively injecting gas according to a certain step gas injection speed; performing a gas injection brine displacement experiment on a simulated rock core of saturated brine, establishing saturation of bound water, and recording related experiment data;

4) setting back pressure according to certain stepped gas injection speed; injecting a simulated rock core under bound water to simulate a gas production process, and recording related experimental data in the experimental process; testing the gas logging permeability of the simulated rock core after the simulation of the gas production process is finished;

5) and after the test is finished, performing reverse blocking removal treatment by using clear water to displace the rock core, recording relevant experimental data in the blocking removal process, testing the pore permeability parameter after blocking removal, and evaluating the injection capacity change of the simulated rock core and the recovery condition of the pore permeability parameter.

During testing, the salt plugging polluted core and the uncontaminated simulated core are respectively adopted to carry out gas-water co-injection so as to simulate the invasion of the water body in the gas production process.

4) adjusting the injection and production direction, injecting saturated brine and injected gas from a large section at the same time, flowing out from a small section to simulate the gas production process, and testing the gas logging permeability of the simulated rock core after the experiment temperature and pressure are stable; repeating the steps in the above way to simulate the cyclic injection and production process;

5) recording displacement time, pump reading, injection pressure, injection speed, back pressure, differential pressure gauge reading and thermometer reading at each position in the experimental process, and metering air quantity and water quantity; and after the simulation experiment of the circulating injection and production process is completed, performing reverse blocking removal treatment by using clear water to displace the rock core, recording relevant experimental data in the blocking process, and testing pore permeability parameters after blocking removal.

S1.24. simulation experiment for drying salting-out and blockage removal

And (3) performing blockage removal by reversely injecting clear water from the simulated rock core, testing physical property parameters of the simulated rock core before and after blockage removal, recording pressure data of each section of the displacement system, and evaluating the injection capacity of the simulated rock core before and after blockage removal and the change of the pore permeability parameters.

S2 method for evaluating drying salting-out effect of near wellbore zone of gas storage injection and production well

The deformation of the pore space and the change of the fluid are described, and the deformation and the change of the fluid are characterized by the ratio of the initial physical parameters to the current physical parameters or the change degree of the physical parameters, as follows:

or

Wherein P is groundFormation pressure, T is formation temperature, ω is mineralization, S_wiIs the initial average water saturation, S_wIs the current average water saturation, v_inIs the gas injection velocity, v_outIs gas production rate, r_eIs the radius of gas supply, E is the energy of the water body, and s is the epidermal factor.

8. The method for evaluating the drying salting-out effect of the near wellbore zone of the gas storage injection well as claimed in claim 7, wherein in the step S1.12, the permeability and the slippage correction are needed: in the experimental determination, the mean pressure was varied several times

a relation curve; from formulas

It is seen that K_aAnd

9. The method for evaluating the drying salting-out effect of the near-wellbore region of the gas storage injection and production well according to claim 7, wherein in the step S1.21, in the drying salting-out effect speed sensitivity experiment process, an injection medium adopted in the process of saturating the simulated core is saturated brine.