CN109856030B - Imbibition experimental device and method for determining imbibition extraction degree - Google Patents

Abstract

The invention provides a imbibition experimental device and a method for determining imbibition extraction degree, which relate to the imbibition field, wherein the experimental device comprises: the seepage bottle is filled with water and a core sample, the seepage bottle is provided with an open end, a test tube is arranged at the open end, scale marks are marked on the test tube from the upper end to the lower end, and the water level in the seepage bottle is not lower than the scale mark at the lowest end of the test tube; the micro-pressure pump is used for providing water with preset pressure to the imbibition bottle; the hanging frame is used for hanging the core sample and is placed on the gravity sensing device, and the gravity sensing device is electrically connected with the data acquisition system; wherein, the infiltration bottle is provided with the water inlet, and the water inlet passes through connecting device with the micropressure pump and is connected, and connecting device includes: the hydraulic control valve is in an open state when the hydraulic control valve detects that the pressures at two sides are unequal; when the hydraulic control valve detects that the pressures at the two sides are equal, the hydraulic control valve is in a closed state. The seepage and suction experimental device provided by the invention is convenient to assemble, high in measurement precision and wide in application range.

Description

Imbibition experimental device and method for determining imbibition recovery degree

Technical Field

The invention relates to the field of imbibition in petroleum engineering, and in particular to an imbibition experimental device and a method for determining an imbibition production degree.

Background technique

Tight rock reservoirs belong to the type of unconventional oil resources, and are mostly found in unconventional reservoirs with low porosity and low permeability. Due to the long-term immersion of formation water, underground rocks have shown hydrophilic characteristics. When oil and water coexist in the pores of rocks, the oil-water interface presents a curved liquid surface due to the difference in wettability. The pressures on both sides of the curved liquid surface are not equal, and the oil phase pressure is higher than the water phase pressure, thus forming a pressure difference. The force formed by the pressure difference is the capillary force. Under the action of the capillary force, water will enter the rock pores and displace the crude oil, which is the imbibition process.

At present, imbibition has become an important mechanism for studying tight oil reservoirs and low permeability oil reservoirs. When studying the imbibition of tight and low permeability rocks, it is necessary to measure the imbibition oil production. In the prior art, the method for measuring the oil production during the imbibition process usually adopts the core weighing method, which is to suspend the rock and immerse it in the formation water, connect the rock to the balance, and use the force balance of the three forces of rock gravity, buoyancy and balance support force. By reading the data of the balance, the gravity change during the rock imbibition process can be obtained, and the oil production can be obtained through further calculation.

In the measurement process using this method, the imbibition oil production is not intuitive enough, and the volume of the imbibed oil film cannot be directly measured. In addition, the applicant found that as the imbibition process proceeds, the rock is gradually placed in a mixed solution of formation water and crude oil, the density of the solution gradually decreases, and the overall volume of the solution remains unchanged, causing the buoyancy of the rock to gradually decrease, and the impact of the change in buoyancy on the measurement results cannot be measured, resulting in a certain error in the measurement results. At the same time, as the imbibition process proceeds, the formation water continues to evaporate, and the buoyancy of the rock changes with the evaporation of the formation water, which also makes the measurement results inaccurate.

It should be noted that the above introduction to the technical background is only for the convenience of providing a clear and complete description of the technical solutions of the present invention and facilitating the understanding of those skilled in the art. It cannot be considered that the above technical solutions are well known to those skilled in the art simply because these solutions are described in the background technology section of the present invention.

Summary of the invention

To achieve the above purpose, the present application provides an imbibition experimental device with high measurement accuracy and simple operation. The device can be used to quantitatively and qualitatively obtain the oil production during the imbibition process under different experimental conditions and its changes over time. The technical solution is as follows:

A percolation experiment device comprises: a percolation bottle, the percolation bottle having a hollow cavity, the hollow cavity containing water and a core sample, the percolation bottle having an open end, the open end being provided with a test tube, the test tube having an upper end and a lower end opposite to each other, scale lines being marked from the upper end to the lower end, the water level in the percolation bottle being not lower than the scale line at the lowest end of the test tube; a micro-pressure pump, the micro-pressure pump being used to provide water of a predetermined pressure into the percolation bottle; a hanger for hanging the core sample, the hanger being placed on a gravity sensing device, the gravity sensing device being electrically connected to a data acquisition system; wherein the percolation bottle is provided with a water inlet, the water inlet being connected to the micro-pressure pump via a connecting device, the connecting device comprising: a hydraulic control valve, which is in an open state when the hydraulic control valve detects that the pressures on both sides are unequal; and is in a closed state when the hydraulic control valve detects that the pressures on both sides are equal.

As a preferred embodiment, the infiltration experimental device further comprises: a siphon catheter and a beaker, wherein the siphon catheter has two opposite ends, one end of which is connected to the infiltration bottle, and the other end of which is connected to the beaker.

As a preferred implementation, a switch control device is provided on the siphon conduit, and the switch control device is specifically a regulating valve capable of changing the opening degree.

As a preferred embodiment, the siphon catheter has a suction section, the suction section is located in the infiltration bottle, and a plurality of water outlet holes are arranged on the suction section.

As a preferred embodiment, the imbibition experiment device further comprises: a constant temperature box, and the constant temperature box is used to adjust the temperature of the imbibition bottle.

A method for determining the degree of imbibition recovery based on the imbibition experimental device, the method comprising: receiving the height from the water inlet of the imbibition bottle to the top of the liquid surface; determining the predetermined pressure of the micro-pressure pump according to the height; receiving the first data measured by the gravity sensing device; starting the micro-pressure pump and receiving the second data measured by the gravity sensing device; determining the volume of oil displaced by imbibition water according to the first data, the second data, the density of water, and the density of oil; determining the degree of imbibition recovery according to the volume of oil displaced by imbibition water, core oil saturation, core porosity, core length, and core diameter.

As a preferred implementation, the calculation formula for the imbibition recovery degree is:

In the formula,

Where, S ₀ represents the oil saturation of the core, in %;

Φ represents the core porosity, in %;

L represents the core length in cm;

D represents the core diameter in cm;

_Mi represents the mass of the core sample at time i, in g;

_m0 represents the initial mass of the core sample, in g;

R _i represents the imbibition recovery degree of the core sample at time i, in %;

ρ _w is the density of injected water, in g/cm ³ ;

ρ _o is the density of oil, in g/cm ³ ;

ΔV is the volume of oil displaced by water at time i relative to the initial time, in cm ³ .

As a preferred implementation, ΔV in the absorption extraction degree calculation formula can also be obtained by reading the scale line on the absorption bottle.

As a preferred implementation, the predetermined pressure determined by the micro-pressure pump is:

P＝ρ _w g(H _i +A)

in,

A represents the height from the water inlet of the infiltration bottle to the oil-water interface, in mm;

g represents the acceleration due to gravity, with the unit being m/s ² ;

_Hi represents the oil height in mm;

ρ _w is the density of injected water, in g/cm ³ .

As a preferred implementation, the setting deviation of the micro-pressure pump is 1 Pa, and the accuracy of the water level rise in the infiltration bottle is 0.1 mm.

The imbibition experimental device provided by the present invention has the following advantages and characteristics: the imbibition experimental device is provided with a micro-pressure pump, and the micro-pressure pump is set with a predetermined pressure. When the water pressure on the core sample decreases, the micro-pressure pump can timely add water to the imbibition bottle, thereby keeping the water pressure in the imbibition bottle unchanged, and ensuring that the water pressure on the core sample is always maintained at the predetermined pressure. Since the buoyancy on the core sample is equivalent to the gravity of the oil-water mixture displaced by the core sample, that is, _Fbuoyancy = _{ρliquid gVdisplacement} = _{ρliquid ghliquid} ·S = _Fpressure , by maintaining the predetermined pressure on the core sample, it can be ensured that the buoyancy on the core sample during the imbibition process remains unchanged. Therefore, when the water pressure in the imbibition bottle decreases, water is added to the imbibition bottle by the micro-pressure pump, which can ensure that the buoyancy on the core sample remains unchanged, thereby avoiding the influence of the buoyancy change on the reading of the gravity sensing device, and improving the accuracy of the measurement result.

In the imbibition experimental device provided by the present invention, a gravity sensing device for measuring changes in the mass of core samples is electrically connected to a data acquisition system, and the data acquisition system records the gravity sensing device in real time. The data acquisition system automatically records changes in the measurement data of the gravity sensing device, saving time and effort and reducing workload.

By recording and analyzing the data measured by the gravity sensing device, the volume of crude oil production can be calculated. At the same time, the imbibition bottle in the imbibition experimental device is provided with a scale line, and the produced oil floats on the water surface. The volume of the produced oil can be directly read and recorded through the scale line, so that the calculated crude oil volume can be verified, which improves the accuracy of the calculation results. The obtained crude oil volume can further calculate the degree of imbibition recovery. This parameter has important guiding significance for estimating the imbibition production effect of actual tight reservoirs and improving the recovery rate of tight reservoirs.

With reference to the following description and accompanying drawings, the specific embodiments of the present application are disclosed in detail, indicating the way in which the principles of the present application can be adopted. It should be understood that the embodiments of the present application are not limited in scope. Within the scope of the spirit and clauses of the appended claims, the embodiments of the present application include many changes, modifications and equivalents.

Features described and/or illustrated with respect to one embodiment may be used in the same or similar manner in one or more other embodiments, combined with features in other embodiments, or substituted for features in other embodiments.

It should be emphasized that the term “include/comprises” when used herein refers to the presence of features, integers, steps or components, but does not exclude the presence or addition of one or more other features, integers, steps or components.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of the structure of an imbibition experiment device in an embodiment of the present application.

Description of reference numerals:

1. Micro-pressure pump; 2. Water container; 3. Pipeline; 4. Hydraulic control valve; 5. Imbibition bottle; 6. Imbibition produced oil; 7. Copper wire; 8. Core sample; 9. Siphon catheter; 10. Beaker; 11. Hanger; 12. Precision electronic balance; 13. Data cable; 14. Data acquisition system; 15. Constant temperature box; 16. Bottom cover of the mbibition bottle.

Detailed ways

The technical solution of the present invention will be described in detail below in conjunction with the accompanying drawings and specific implementation methods. It should be understood that these implementation methods are only used to illustrate the present invention and are not used to limit the scope. After reading the present invention, various equivalent forms of modifications to the present invention by those skilled in the art all fall within the scope defined by the claims attached to this application.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

It should be noted that when an element is referred to as being "disposed on" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used herein are for illustrative purposes only and are not intended to be the only implementation method.

The embodiment of the present application provides an infiltration experiment device, please refer to FIG1, the infiltration experiment device comprises: an infiltration bottle 5, the infiltration bottle 5 has a hollow cavity, the hollow cavity is filled with water and a core sample 8, the infiltration bottle 5 has an open end, the open end is provided with a test tube, the test tube has an upper end and a lower end opposite to each other, and scale lines are marked from the upper end to the lower end, and the water level in the infiltration bottle 5 is not lower than the scale line at the lowest end of the test tube; a micro-pressure pump 1, the micro-pressure pump 1 is used to pump water into the infiltration bottle 5 Provide water of a predetermined pressure; a hanger 11 for hanging the core sample 8, wherein the hanger 11 is placed on a gravity sensing device, and the gravity sensing device is electrically connected to a data acquisition system 14; wherein the imbibition bottle 5 is provided with a water inlet, and the water inlet is connected to the micro-pressure pump 1 via a connecting device, and the connecting device comprises: a hydraulic control valve 4, which is in an open state when the hydraulic control valve 4 detects that the pressures on both sides are unequal; and is in a closed state when the hydraulic control valve 4 detects that the pressures on both sides are equal.

The imbibition experimental device provided by the present invention has the following advantages and characteristics: the imbibition experimental device is provided with a micro-pressure pump 1, and the micro-pressure pump 1 is set with a predetermined pressure. When the water pressure on the core sample decreases, the micro-pressure pump 1 can timely add water to the imbibition bottle, thereby keeping the water pressure in the imbibition bottle 5 unchanged, and ensuring that the water pressure on the core sample 8 is always maintained at the predetermined pressure. Since the buoyancy on the core sample 8 is equivalent to the gravity of the oil-water mixture displaced by the core sample 8, that is, _Fbuoyancy = _{ρliquid gVdisplacement} = _{ρliquid ghliquid} ·S = _Fpressure , by maintaining the predetermined pressure on the core sample 8, the buoyancy on the core sample 8 during the imbibition process can be ensured to remain unchanged. Therefore, when the water pressure in the imbibition bottle 5 decreases, water is added to the imbibition bottle 5 by the micro-pressure pump 1, which can ensure that the buoyancy on the core sample 8 remains unchanged, thereby avoiding the influence of the buoyancy change on the reading of the gravity sensing device, and improving the accuracy of the measurement result.

In the infiltration experimental device provided by the present invention, the gravity sensing device used to measure the mass change of the core sample 8 is electrically connected to the data acquisition system 14, and the data acquisition system 14 records the gravity sensing device in real time. The data acquisition system 14 automatically records the changes in the measurement data of the gravity sensing device, saving time and effort and reducing workload.

By recording and analyzing the data measured by the gravity sensing device, the volume of crude oil output can be calculated. At the same time, the imbibition bottle 5 in the imbibition experimental device is provided with a scale line, and the produced oil floats on the water surface. The volume of the produced oil can be directly read and recorded through the scale line, so that the calculated crude oil volume can be verified, and the accuracy of the calculation result is improved. The imbibition recovery degree can be further calculated by the obtained crude oil volume. This parameter has important guiding significance for estimating the imbibition mining effect of the actual tight reservoir and improving the recovery rate of the tight reservoir.

The infiltration bottle 5 is a transparent container for containing formation water and core samples 8, which has a hollow cavity structure. The infiltration bottle 5 has a relative upper end and lower end, and a water inlet is provided at the lower end near the bottom cover 16 of the infiltration bottle, so that it is more conducive to the micro-pressure pump 1 to control the water pressure in the infiltration bottle 5. The upper end of the infiltration bottle 5 is open. Specifically, the infiltration bottle 5 includes a main body section, which can be cylindrical and filled with core samples 8 and water. The upper end of the infiltration bottle 5 is provided with an open end, and a test tube is provided at the open end. The test tube has a relative upper end and lower end, and scale lines are marked from the upper end to the lower end. The water level in the infiltration bottle 5 is not lower than the scale line at the lowest end of the test tube. A transition section may be provided between the main section and the test tube, wherein the transition section has upper and lower opposite ends, the upper end of the transition section is matched and connected to the test tube, and the lower end of the transition section is matched and connected to the main section, and the transition section has a conical structure.

As the imbibition process progresses, crude oil is slowly produced in the core sample 8. Since the density of the imbibition oil 6 is less than that of water, the imbibition oil 6 will float on the surface of the water. When the water level in the imbibition bottle 5 is not lower than the scale line at the bottom of the test tube, the imbibition oil 6 can float to the scale line of the imbibition bottle 5, and the volume of the imbibition oil 6 can be directly read and recorded by the scale line. In order to better further distinguish water from the imbibition oil 6, the injected water can be blue. Of course, the color of the injected water is not specifically limited, and it can be distinguished from the produced oil. The output of the produced oil is small and the oil production rate is slow. The diameter of the test tube should not be too large, so that a more accurate reading can be obtained. By setting scale lines on the test tube, the amount of oil production and the oil production rate can be intuitively observed during the imbibition oil production process, and the imbibition oil production volume can be obtained by reading the height difference of the oil surface.

The micro-pressure pump 1 is specifically a constant pressure pump, which is provided with a water container 2, so that water can be provided to the water inlet of the imbibition bottle 5, and the water body can specifically be formation water. When in use, the micro-pressure pump 1 pre-sets a predetermined pressure, so that the water outlet pressure can be controlled. The water inlet of the imbibition bottle 5 is connected to the micro-pressure pump 1 through a connecting device, and the connecting device includes: a hydraulic control valve 4, when the hydraulic control valve 4 detects that the pressures on both sides are not equal, it is in an open state; when the hydraulic control valve 4 detects that the pressures on both sides are equal, it is in a closed state.

Specifically, the micro-pressure pump 1 and the infiltration bottle 5 can be connected through a pipeline 3, and a hydraulic control valve 4 is provided on the pipeline 3. When the volume and properties of the liquid in the infiltration bottle 5 change due to the reduction of water content or the influence of produced oil, the pressures on both sides of the hydraulic control valve 4 are not equal, that is, the hydraulic pressure acting on the hydraulic control valve 4 is not equal to the predetermined pressure set by the micro-pressure pump 1, and the hydraulic control valve 4 is in an open state. The micro-pressure pump 1 replenishes water for the infiltration bottle 5 until the pressures on both sides of the hydraulic control valve 4 are equal, the hydraulic control valve 4 is closed, and the water supply ends.

In this embodiment, the infiltration experiment device further includes: a siphon tube 9 and a beaker 10 . The siphon tube 9 has two opposite ends, one end of which is connected to the infiltration bottle 5 , and the other end of which is connected to the beaker 10 .

Specifically, the siphon conduit 9 can be made of plastic material, and the specific material is not limited. It has two opposite ends, one end is connected to the infiltration bottle 5, and the infiltration bottle 5 can be provided with a water outlet, the diameter of the water outlet matches the diameter of the siphon conduit 9, and the water outlet can be seamlessly connected with the siphon conduit 9 to prevent water leakage.

The siphon catheter 9 may further have a suction section, and the suction section is located in the imbibition bottle 5. A plurality of water outlet holes may be provided on the suction section, so as to simulate the perforation of the well and further simulate the flow of water. The siphon catheter 9 can slowly discharge the water in the imbibition bottle 5, so as to place the core sample 8 in a dynamic water flow, realize a dynamic imbibition process, and more realistically simulate the imbibition process of water replacing crude oil in a tight oil reservoir environment. When water flows out of the imbibition bottle 5 due to the siphon catheter 9, the water pressure in the bottle decreases, the pressures on both sides of the hydraulic control valve 4 are not equal, the hydraulic control valve 4 is in an open state, and the micro-pressure pump 1 replenishes water for the imbibition bottle 5 until the pressures on both sides of the hydraulic control valve 4 are equal, the hydraulic control valve 4 is closed, and the water supply ends.

In one embodiment, the siphon conduit 9 is provided with a switch control device, which is specifically a regulating valve capable of changing the opening. By changing the opening of the regulating valve, the water flow rate can be controlled, and thus the dynamic water flow rate in the dynamic infiltration process can be adjusted. In addition, when the regulating valve is closed, the water body is in a static state, and the static infiltration process can be simulated. When the regulating valve is opened, the dynamic infiltration process can be simulated.

In this embodiment, when the micro-pressure pump 1 provides water to the infiltration bottle 5, the water level in the infiltration bottle 5 rises to:

Wherein, h represents the height of water level rise, in mm;

_Hi represents the oil height in mm;

ρ _w is the density of injected water, in g/cm ³ ;

ρ _o is the density of oil, in g/cm ³ .

Specifically, as the imbibition reaction proceeds, water can gradually replace the crude oil in the core sample 8, and the overall volume of the solution in the imbibition bottle 5 remains unchanged. As crude oil is produced, the core sample 8 is gradually placed in an oil-water mixture. The density of the oil-water mixture is less than the density of pure water, and the cross-sectional area of the core sample 8 is constant, resulting in a decrease in the pressure on the core sample 8. From the formula: _Ffloat = _{ρliquid gVdischarge} = _{ρliquid ghliquid} ·S = _Fpressure , it can be seen that the reduction in the pressure on the core sample 8 will inevitably lead to a reduction in the buoyancy of the core sample 8. Therefore, in order to keep the buoyancy of the core sample 8 unchanged during the imbibition process, it is necessary to add water to the imbibition bottle 5 to increase the volume of the oil-water mixture in the imbibition bottle 5 so that the hydraulic pressure on the core sample 8 remains unchanged, thereby eliminating the effect of the produced oil on the buoyancy.

The core sample 8 is suspended by a hanger 11, and the hanger 11 is placed on the gravity sensing device. The hanger 11 is provided with a hook, and the core sample 8 is connected to the hook through a copper wire 7. The copper wire 7 passes through the test tube on the infiltration bottle 5, so that the core sample 8 can be suspended. In order to prevent the copper wire 7 from contacting the inner wall of the test tube when the core sample 8 is suspended, the diameter of the test tube should be larger than the diameter of the copper wire 7. Since the core sample 8 has a certain weight, the copper wire 7 can keep the core sample 8 in a vertical state in the water when the core sample 8 is suspended.

The gravity sensing device is used to measure the mass change of the core sample 8, the copper wire 7 and the hanger 11. In the imbibition experiment, by observing and recording the data results measured by the gravity sensing device, the mass change of the core sample 8 can be obtained, thereby further obtaining the oil production. Specifically, the gravity sensing device can be a precision electronic balance 12, which can accurately measure the mass and mass change of the core sample 8, the copper wire 7 and the hanger 11, and the measurement result accuracy is 0.0001g. The precision electronic balance 12 is further electrically connected to the data acquisition system 14, and the data acquisition system 14 can be a computer. The electrical connection method can be a wired connection. Of course, the electrical connection method can also be a wireless connection, such as using WIFI, infrared, Bluetooth and other technologies in the prior art, or other wireless communication technologies can also be used. This application is not specifically limited here. Preferably, the precision electronic balance 12 is connected to the data acquisition system 14 via a data line 13. The data acquisition system 14 connected to the precision electronic balance 12 will record and automatically record the changes in the readings in real time. The whole set of experimental equipment reduces the measurement error and the workload at the same time.

In one embodiment, the infiltration experimental device further includes: a thermostat 15, which is used to adjust the temperature of the infiltration bottle 5. The thermostat 15 is a transparent box structure, and the micro-pressure pump 1, the infiltration bottle 5, the hanger 11, the siphon catheter 9, the beaker, the precision electronic balance 12 and other instruments can be located in the thermostat 15, thereby providing a suitable external environment for the infiltration process.

The present application also provides a method for determining the imbibition extraction degree based on the above-mentioned imbibition experimental device, the method comprising:

S10: receiving the height from the water inlet of the infiltration bottle 5 to the top of the liquid surface; determining the predetermined pressure of the micro-pressure pump 1 according to the height;

S20: receiving first data measured by the gravity sensing device;

S30: Turn on the micro-pressure pump 1 to receive the second data measured by the gravity sensing device;

S40: determining the volume of oil displaced by the absorbed water according to the first data, the second data, the density of water, and the density of oil;

S50: Determine the imbibition recovery degree according to the volume of oil displaced by the imbibition water, the oil saturation of the core, the porosity of the core, the length of the core and the diameter of the core.

After setting the predetermined pressure of the micro-pressure pump 1, start recording the first data recorded by the gravity sensing device. In step S20, the first data is specifically the mass of the core sample initially measured. Turn on the micro-pressure pump 1 and start the imbibition experiment. During the experiment, the micro-pressure pump 1 will add water to the imbibition bottle 5 according to the hydraulic pressure changes in the imbibition bottle 5 to maintain the predetermined pressure on the core sample 8. At the same time, the gravity sensing device continuously records the mass changes of the core sample 8 and obtains the second data. In step S30, the second data is specifically the mass of the core sample measured at time i. Of course, the first data and the second data are not the true mass of the core sample 8, but the difference between the first data and the second data can reflect the mass change of the core sample 8.

In this embodiment, the calculation formula of the imbibition extraction degree is:

In the formula,

Where, S ₀ represents the oil saturation of the core, in %;

Φ represents the core porosity, in %;

L represents the core length in cm;

D represents the core diameter in cm;

_Mi represents the mass of the core sample at time i, in g;

m ₀ represents the initial core sample mass in g;

R _i represents the imbibition recovery degree of the core sample at time i, in %;

ρ _w is the density of injected water, in g/cm ³ ;

ρ _o is the density of oil, in g/cm ³ ;

ΔV is the volume of oil displaced by water at time i relative to the initial time, in cm ³ .

Specifically, the original oil-bearing volume of the core is:

Assume that the buoyancy of the core in the imbibition bottle 5 is F, and the equation at the initial moment is:

At the i-th moment, the equation is satisfied:

From equations (2) and (3), the volume of oil absorbed is:

Wherein, V _wi represents the volume of bound water in the rock sample, in units of cm ³ .

In one embodiment, ΔV in the calculation formula for the degree of absorption and extraction can also be obtained by reading the scale line on the absorption bottle 5 .

Therefore, during the imbibition experiment, ΔV can be obtained by two methods: the first method is to obtain the mass change of the core sample 8 by reading the data recorded by the precision electronic balance 12, and to obtain the volume of the oil replaced by the imbibition water by formula (4); the second method is to directly read the scale on the imbibition bottle 5, and to obtain the volume of the oil replaced by the imbibition water by reading the height difference of the oil film liquid surface. Therefore, during the experiment, the imbibition experimental device can simultaneously obtain the two parameters of the volume of the imbibition produced oil 6 and the mass change of the core sample 8, which can not only intuitively reflect the oil production, but also improve the accuracy of the calculation results. At the same time, these two parameters can be verified with each other, which greatly improves the experimental efficiency.

In this embodiment, the predetermined pressure determined by the micro-pressure pump 1 is:

P＝ρ _w g(H _i +A)

in,

A represents the height from the water inlet of the infiltration bottle to the oil-water interface, in mm;

g represents the acceleration due to gravity, with the unit being m/s ² ;

_Hi represents the oil height in mm;

ρ _w is the density of injected water, in g/cm ³ .

In this embodiment, the setting deviation of the micro-pressure pump 1 is 1 Pa, and the accuracy of the water level rise height is 0.1 mm.

From the formula P = ρ _w g (H _i + A), we can get: When the deviation of the setting value of the micro-pressure pump 1 is 1 Pa, the error of _Hi + A is 0.1 mm. Therefore, by setting the micro-pressure pump 1 to supply water to the infiltration bottle 5, the rising speed of the liquid level can be accurately controlled.

In order to better understand the present application, the imbibition experimental device provided by the present application will be explained below in conjunction with a specific application scenario.

A device for infiltration experiment, please refer to FIG1, the device for infiltration experiment comprises: an infiltration bottle 5, the infiltration bottle 5 has a hollow cavity, the hollow cavity is filled with water and a core sample 8, the infiltration bottle 5 has an open end, the open end is provided with a test tube, the test tube has an upper end and a lower end opposite to each other, and scale lines are marked from the upper end to the lower end, and the water level in the infiltration bottle 5 is not lower than the scale line at the lowest end of the test tube; a micro-pressure pump 1, the micro-pressure pump 1 is used to provide water with a predetermined pressure into the infiltration bottle 5 ; A hanger 11 for hanging the core sample 8, the hanger 11 is placed on a precision electronic balance 12, and the precision electronic balance 12 is connected to a data acquisition system 14 via a data line 13; wherein the infiltration bottle 5 is provided with a water inlet, the water inlet is connected to the micro-pressure pump 1 via a pipeline 3, a hydraulic control valve 4 is provided on the pipeline, when the hydraulic control valve 4 detects that the pressures on both sides are unequal, it is in an open state; when the hydraulic control valve 4 detects that the pressures on both sides are equal, it is in a closed state.

Furthermore, the infiltration experiment device also includes: a siphon tube 9 and a beaker 10, and the infiltration bottle 5 is provided with a water outlet that can be seamlessly connected with the siphon tube 9. The siphon tube 9 has a suction section, and the suction section is located in the infiltration bottle 5. The suction section is provided with a plurality of water outlet holes, so as to simulate the perforation of a well. The siphon tube 9 guides the water in the infiltration bottle 5 into the beaker 10, and the siphon tube 9 is provided with a regulating valve that can change the opening.

The infiltration bottle 5 comprises: a main body section, which is cylindrical and contains a core sample 8 and water, and the water is blue. A transition section may be provided between the main body section and the test tube, and the transition section has upper and lower opposite ends, the upper end of the transition section is matched and connected with the test tube, and the lower end of the transition section is matched and connected with the main body section, and the transition section has a conical structure.

When the volume and properties of the liquid in the infiltration bottle 5 change due to water discharge from the siphon tube 9, water volatilization or the influence of produced oil, the pressures on both sides of the hydraulic control valve 4 are not equal, that is, the hydraulic pressure acting on the hydraulic control valve 4 is not equal to the predetermined pressure set by the micro-pressure pump 1, the hydraulic control valve 4 is in an open state, and the micro-pressure pump 1 replenishes water to the infiltration bottle 5 until the pressures on both sides of the hydraulic control valve 4 are equal, the hydraulic control valve 4 is closed, and the water supply ends.

During the experiment, the micro-pressure pump 1 is set to a predetermined pressure of 0.255MPa, the bottom diameter of the infiltration bottle 5 is 10cm, and the distance from the water inlet of the infiltration bottle 5 to the top of the liquid surface is about 20cm. As the infiltration process proceeds, water continues to evaporate, and water in the infiltration bottle 5 continues to flow out through the siphon tube 9, accompanied by the production of infiltration oil 6, which causes the hydraulic pressure of the core sample 8 to decrease, resulting in a decrease in buoyancy. The specific principle has been explained above, and this application will not be repeated in detail. At this time, the hydraulic control valve 4 is opened, and the micro-pressure pump 1 replenishes water for the infiltration bottle 5 until the pressure on both sides of the hydraulic control valve 4 is equal, the hydraulic control valve 4 is closed, and the water supply ends.

By recording the data measured by the precision electronic balance 12 through the data acquisition system 14, the volume of crude oil output can be calculated, and then the imbibition recovery degree can be calculated through a proprietary formula. This parameter can be used to estimate the actual imbibition recovery effect of tight reservoirs, which has important guiding significance for improving the recovery rate of tight reservoirs. Since the buoyancy of the core sample 8 can always be kept unchanged during the entire experiment, the mass change of the core sample 8 during the imbibition process can be directly obtained by measuring the data changes of the precision electronic balance 12, and then converted into the volume of the produced crude oil. In addition, the imbibition produced oil 6 will float on the scale position of the imbibition bottle 5. By reading the height difference of the produced oil surface, the volume of the seeping crude oil can be obtained, so that the converted crude oil volume can be further verified.

During the imbibition experiment, the imbibition experimental device can obtain the imbibition oil 6 by directly reading the scale line on the imbibition bottle 5. Therefore, the two parameters of the imbibition oil production volume and the mass change of the core sample 8 can be obtained at the same time, and can be verified with each other, which can greatly improve the accuracy of the calculation results. The obtained crude oil production volume can be further obtained through a proprietary formula to obtain the imbibition recovery degree, so as to study the recovery rate of tight reservoirs.

The proprietary formula is as follows:

In the formula,

Where, S ₀ represents the oil saturation of the core, in %;

Φ represents the core porosity, in %;

L represents the core length in cm;

D represents the core diameter in cm;

_Mi represents the mass of the core sample at time i, in g;

m ₀ represents the initial core sample mass in g;

R _i represents the imbibition recovery degree of the core sample at time i, in %;

ρ _w is the density of injected water, in g/cm ³ ;

ρ _o is the density of oil, in g/cm ³ ;

ΔV is the volume of oil displaced by water at time i relative to the initial time, in cm ³ .

The imbibition experimental device provided in the embodiment of the present application has the following advantages over the measuring device in the prior art:

(1) During the imbibition experiment, the imbibition experimental device can simultaneously obtain two parameters: the imbibition oil production volume and the change in core sample mass. These two parameters can be verified with each other, which can greatly improve the accuracy of the calculation results.

(2) The imbibition experimental device can simulate both static imbibition and dynamic imbibition processes.

(3) The imbibition experiment device can avoid the influence of the buoyancy change of the core sample on the experimental results by controlling the hydraulic pressure in the imbibition bottle, thereby ensuring the accuracy of the measurement results.

(4) The micro-pressure pump and precision electronic balance in the infiltration experimental device have high measurement accuracy, ensuring the accuracy of the experimental results.

(5) By connecting the precision electronic balance to the data acquisition system, data can be automatically recorded and saved in real time, saving time and effort and reducing workload.

(6) The imbibition experiment device is easy to operate and has high measurement accuracy. Compared with the nuclear magnetic resonance imaging measurement device in the prior art, it has low cost and a wide range of applications.

The above embodiments are only for illustrating the technical concept and features of the present application, and their purpose is to enable people familiar with the technology to understand the content of the present application and implement it accordingly, and they cannot be used to limit the protection scope of the present application. Any equivalent changes or modifications made according to the spirit of the present application should be included in the protection scope of the present application.

All articles and references disclosed, including patent applications and publications, are incorporated herein by reference for all purposes. The term "consisting essentially of..." to describe a combination should include the identified elements, ingredients, parts or steps and other elements, ingredients, parts or steps that do not substantially affect the basic novel characteristics of the combination. The use of the terms "comprising" or "including" to describe a combination of elements, ingredients, parts or steps herein also contemplates embodiments that consist essentially of these elements, ingredients, parts or steps. By using the term "may", it is intended to indicate that any attribute described that "may" be included is optional.

Multiple elements, compositions, parts or steps can be provided by a single integrated element, composition, part or step. Alternatively, a single integrated element, composition, part or step can be divided into separate multiple elements, compositions, parts or steps. The disclosure "one" or "an" used to describe an element, composition, part or step is not intended to exclude other elements, compositions, parts or steps.

It should be understood that the above description is for illustration and not for limitation. Many embodiments and many applications beyond the examples provided will be apparent to those skilled in the art upon reading the above description. Therefore, the scope of the present teachings should not be determined with reference to the above description, but should be determined with reference to the appended claims and the full scope of equivalents possessed by such claims. For the purpose of comprehensiveness, all articles and references, including disclosures of patent applications and publications, are incorporated herein by reference. The omission of any aspect of the subject matter disclosed herein in the preceding claims is not intended to be a waiver of the subject matter, nor should it be considered that the applicant has not considered the subject matter as part of the disclosed application subject matter.

Claims (5)

1. A method for determining the degree of imbibition extraction of an imbibition experimental device, characterized in that the imbibition experimental device comprises: An infiltration bottle, the infiltration bottle having a hollow cavity, the hollow cavity containing water and a core sample, the infiltration bottle having an open end, the open end being provided with a test tube, the test tube having an upper end and a lower end opposite to each other, scale lines being marked from the upper end to the lower end, and the water level in the infiltration bottle not being lower than the scale line at the lowest end of the test tube; A micro-pressure pump is used to provide water of a predetermined pressure into the infiltration bottle; the predetermined pressure determined by the micro-pressure pump is: P＝ρ _w g(H _i +A) in, A represents the height from the water inlet of the infiltration bottle to the oil-water interface, in mm; g represents the acceleration due to gravity, with the unit being m/s ² ; _Hi represents the oil height in mm; ρ _w represents the density of the injected water, in units of g/cm ³ , the setting deviation of the micro-pressure pump is 1 Pa; the accuracy of the water level rise in the infiltration bottle is 0.1 mm; The infiltration experiment device further includes: a siphon catheter, the siphon catheter has two opposite ends, one end of which is connected to the infiltration bottle; the siphon catheter can drain the water in the infiltration bottle; the infiltration bottle is provided with a water outlet, the diameter of the water outlet matches the diameter of the siphon catheter; the siphon catheter has a suction section, the suction section is located in the infiltration bottle, and the suction section is provided with a plurality of water outlet holes, so as to simulate the perforation of a well; A hanger for hanging the core sample, the hanger being placed on a gravity sensing device, and the gravity sensing device being electrically connected to a data acquisition system; Wherein, the infiltration bottle is provided with a water inlet, and the water inlet is connected to the micro-pressure pump through a connecting device, and the connecting device comprises: a hydraulic control valve, when the hydraulic control valve detects that the pressures on both sides are not equal, it is in an open state; when the hydraulic control valve detects that the pressures on both sides are equal, it is in a closed state; A thermostatic box, the thermostatic box is used to adjust the temperature of the infiltration bottle; The method comprises: Receive the height from the water inlet of the infiltration bottle to the top of the liquid surface; determine the predetermined pressure of the micro-pressure pump according to the height; thereby controlling the water outlet pressure; receiving first data measured by the gravity sensing device; Turning on the micro-pressure pump to receive the second data measured by the gravity sensing device; Determine the volume of oil displaced by the imbibed water according to the first data, the second data, the density of water, and the density of oil; The imbibition recovery degree is determined based on the volume of oil displaced by the imbibition water, the oil saturation of the core, the porosity of the core, the length of the core and the diameter of the core. 2. The method for determining the degree of imbibition extraction of the imbibition experimental device according to claim 1, characterized in that the imbibition experimental device further comprises: a beaker, and the other end of the siphon tube is connected to the beaker. 3. The method for determining the degree of imbibition extraction of the imbibition experimental device as described in claim 2 is characterized in that a switch control device is provided on the siphon catheter, and the switch control device is specifically a regulating valve that can change the opening degree. 4. The method for determining the imbibition extraction degree according to claim 1, wherein the calculation formula of the imbibition extraction degree is: In the formula, Where, S ₀ represents the oil saturation of the core, in %; Φ represents the core porosity, in %; L represents the core length in cm; D represents the core diameter in cm; _Mi represents the mass of the core sample at time i, in g; _m0 represents the initial mass of the core sample, in g; R _i represents the imbibition recovery degree of the core sample at time i, in %; ρ _w is the density of injected water, in g/cm ³ ; ρ _o is the density of oil, in g/cm ³ ; ΔV is the volume of oil displaced by water at time i relative to the initial time, in cm ³ . 5. The method for determining the degree of imbibition extraction as described in claim 4 is characterized in that ΔV in the calculation formula for the degree of imbibition extraction can also be obtained by reading the scale line on the imbibition bottle.