Method and device for evaluating damage condition of working fluid of tight oil-gas horizontal well

Abstract

The invention discloses a method and a device for evaluating the damage condition of working fluid of a tight oil-gas horizontal well. Drilling standard core plungers at different angles according to the direction of the stratigraphic stratification of the reservoir to be evaluated, and cleaning and drying the standard core plungers; determining the first permeability of a water-saturated core plunger with saturated standard core plunger water; performing a working solution damage test based on the angle of each saturated rock core plunger, and determining a second permeability of each saturated rock core plunger after damage; and determining the damage degree of the reservoir to be evaluated at each angle based on the first permeability and the second permeability, and performing damage condition evaluation based on the damage degree. According to the technical scheme, the characteristic that reservoir damage has spatial anisotropy in the horizontal well drilling process is fully considered, reservoir damage is accurately evaluated by evaluating the damage degree of the working fluid to the core plungers in different spatial orientations, and a powerful theoretical basis is provided for formulating a reasonable reservoir protection strategy.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas exploration, and in particular to a method and a device for evaluating damage of working fluid in a tight oil and gas horizontal well. Background Art

[0002] Compared with conventional oil and gas reservoirs, tight oil and gas reservoirs have special geological conditions and are more susceptible to serious reservoir damage during well construction and development and production. Tight oil and gas reservoirs have typical multi-scale structural characteristics such as pore throats, microcracks, mesoscopic cracks and hydraulic fractures. The gas production process is a multi-scale gas mass transfer process. The gas seepage mechanism in seepage channels of different scales is different, and the reservoir damage mechanism is also different. The damage mechanism has significant spatial multi-scale characteristics.

[0003] Tight oil and gas reservoirs are mostly exploited by horizontal wells. The contact area between the horizontal wellbore and the reservoir rock is greatly increased, and the angle between the wellbore and the formation bedding plane is small. Under the influence of the mechanical properties of the rock, the degree of damage of the working fluid varies in spatial orientation, showing spatial anisotropy.

[0004] Therefore, it is urgent to carry out targeted reservoir damage experimental evaluation to effectively evaluate the damage of tight oil and gas reservoirs. Summary of the invention

[0005] The present invention provides a method and device for evaluating the damage of working fluid in a tight oil and gas horizontal well, so as to effectively evaluate the degree of damage to tight oil and gas reservoirs.

[0006] According to one aspect of the present invention, a method for evaluating damage to working fluid in a tight oil and gas horizontal well is provided, comprising:

[0007] Drill standard core plugs at different angles based on the direction of the reservoir formation to be evaluated, and wash and dry them;

[0008] determining a first permeability of a saturated core plug saturated with water of the standard core plug;

[0009] Performing a working fluid damage test based on the angle of each saturated core plug to determine the second permeability of each saturated core plug after damage;

[0010] The damage degree of the reservoir to be evaluated at each of the angles is determined based on the first permeability and the second permeability, and the damage condition is evaluated based on the damage degree.

[0011] Optionally, the angle includes: parallel bedding and vertical bedding relative to the formation bedding and a preset angle formed with the formation bedding.

[0012] Optionally, the water-saturated core plug is obtained by self-imbibing the standard core plug in contact with formation water in a manner that the bedding plane is perpendicular to the water surface.

[0013] Optionally, the first permeability is determined by:

[0014] The first permeability is calculated based on the viscosity and flow rate of the fluid used for testing, the length and cross-sectional area of ​​the saturated core plug, and the test pressure difference across the two ends of the saturated core plug.

[0015] Optionally, the performing of a working fluid damage test based on the angle of each saturated core plunger to determine the second permeability of the damaged saturated core plunger includes:

[0016] The saturated core plungers are respectively installed into the holders of the corresponding drilling angles;

[0017] Under the same formation temperature and pressure conditions as those of the reservoir to be evaluated, damaging each of the saturated core plungers in the holder with a working fluid;

[0018] The second permeability of each of the saturated core plugs after damage is determined.

[0019] Optionally, the second permeability is determined by:

[0020] The second permeability is calculated based on the viscosity and flow rate of the fluid used for testing after damage, the length and cross-sectional area of ​​the saturated core plug, and the test pressure difference across the saturated core plug.

[0021] Optionally, damaging each of the saturated core plungers in the holder with the working fluid comprises:

[0022] placing the holder in a closed environment and injecting a working fluid into the closed environment;

[0023] Stirring the working fluid by means of a stirring device;

[0024] The working fluid is heated to the temperature of the reservoir to be evaluated to cause damage for a preset time.

[0025] Optionally, determining the damage degree of the reservoir to be evaluated at each of the angles based on the first permeability and the second permeability includes:

[0026] For each angle of the saturated core plug, the damage degree is calculated by the following formula:

[0027]

[0028] Among them, R di is the degree of damage at angle i; K0i is the first permeability of the saturated core plug at angle i, in units of 10 -3 μm 2 ; K di is the second permeability of the saturated core plug at angle i, in units of 10 -3 μm 2 .

[0029] Optionally, the performing of damage assessment based on the damage extent includes:

[0030] Determine the strong damage direction and the weak damage direction according to the damage degree standard and the damage degree of each angle;

[0031] The damage direction is determined according to the strong damage direction and the weak damage direction.

[0032] According to another aspect of the present invention, a device for evaluating damage of working fluid in a tight oil and gas horizontal well is provided, comprising:

[0033] The core drilling unit is used to drill standard core plugs at different angles based on the direction of the reservoir formation to be evaluated and to clean and dry them;

[0034] A first permeability determination unit, used to determine a first permeability of a saturated core plug saturated with water of the standard core plug;

[0035] A second permeability determination unit, configured to perform a working fluid damage test based on the angle of each saturated core plug, and determine a second permeability of each saturated core plug after damage;

[0036] A damage degree determination unit is used to determine the damage degree of the reservoir to be evaluated at each of the angles based on the first permeability and the second permeability, and to perform damage assessment based on the damage degree.

[0037] The technical solution of the embodiment of the present invention is to drill standard core plungers at different angles based on the direction of the stratigraphic bedding of the reservoir to be evaluated and wash and dry them; determine the first permeability of the saturated core plunger saturated with water of the standard core plunger; perform a working fluid damage test based on the angle of each saturated core plunger to determine the second permeability of each saturated core plunger after damage; determine the degree of damage to the reservoir to be evaluated at each angle based on the first permeability and the second permeability, and evaluate the damage based on the degree of damage. The technical solution of the embodiment of the present invention fully considers that during the horizontal well drilling process, reservoir damage has the characteristics of spatial anisotropy. By evaluating the degree of damage of the working fluid to the core plungers in different spatial orientations, the reservoir damage is accurately evaluated, providing a strong theoretical basis for formulating reasonable reservoir protection strategies.

[0038] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0040] Figure 1 This is a flow chart of a method for evaluating damage to working fluid in a tight oil and gas horizontal well provided in Example 1 of the present invention;

[0041] Figure 2 It is a schematic diagram of coring at different orientations of a stratum applicable to the first embodiment of the present invention;

[0042] Figure 3 It is a schematic diagram of a core plunger self-absorbing formation water applicable to the first embodiment of the present invention;

[0043] Figure 4 It is a structural schematic diagram of a device for evaluating working fluid damage in a tight oil and gas horizontal well provided in Example 2 of the present invention. DETAILED DESCRIPTION

[0044] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0045] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0046] Embodiment 1

[0047] Figure 1 This is a flow chart of a method for evaluating the damage of working fluid in a tight oil and gas horizontal well provided by the first embodiment of the present invention. This embodiment is applicable to the evaluation of reservoir damage in a tight oil and gas horizontal well. The method can be executed by a device for evaluating the damage of working fluid in a tight oil and gas horizontal well. The device can be implemented in the form of hardware and / or software. Figure 1 As shown, the method includes:

[0048] S110. Drill standard core plugs at different angles based on the direction of the reservoir formation to be evaluated, and wash and dry them.

[0049] Conduct a well site data survey, and clarify the formation mechanical parameters and the direction of the wellbore in the reservoir based on the formation data and trajectory design of the drilling design, to ensure that subsequent experiments can accurately reflect the actual situation of the formation.

[0050] In the embodiment of the present invention, the angle includes: parallel bedding and vertical bedding relative to the stratum bedding and a preset angle formed with the stratum bedding.

[0051] According to the direction of the stratum bedding, a certain number of standard core plugs are drilled along parallel bedding, vertical bedding and other directions, washed and dried.

[0052] For example, Figure 2 Schematic diagram of coring at different positions of a stratum applicable to the first embodiment of the present invention. Figure 2 In the figure, 1 is the wellbore, 2 is the reservoir rock with bedding, and 3 is the cores in different directions. First, the formation mechanical parameters and the wellbore advancing direction are determined, and then the downhole cores are drilled along the 90°, 45°, 0°, -45° and -90° directions of the wellbore.

[0053] S120, determining a first permeability of the saturated core plug of the standard core plug saturated with water.

[0054] In the embodiment of the present invention, the water-saturated core plug is obtained by self-imbibing the standard core plug in contact with formation water in a manner that the bedding plane is perpendicular to the water surface.

[0055] Figure 3 Schematic diagram of a core plunger self-absorbing formation water applicable to the first embodiment of the present invention, Figure 3 In the figure, 1 is a core plug at different angles, 2 is a formation bedding plane, and 3 is formation water. Specifically, the standard core plug is in contact with the formation water for self-imbibition according to the corresponding angles in a manner that the bedding plane is perpendicular to the water surface.

[0056] Permeability is a measure of the ability of a porous medium to allow fluid to pass through it. It describes how easy it is for a fluid to flow through a porous medium under a certain pressure difference. Factors such as the pore size, shape, distribution, and connectivity between pores in the rock have a significant impact on permeability. The larger the pores and the better the connectivity, the higher the permeability is generally, and the easier it is for fluid to pass through the rock. Different mineral compositions can affect the physical properties of rocks. For example, some minerals may block pores, thereby reducing permeability. Fluid properties such as viscosity and density can also affect permeability. Fluids with higher viscosity encounter greater resistance in different directions when flowing in rocks, and have relatively lower permeability. The initial permeability of drilled core plugs may be different, which reflects the anisotropic characteristics of the reservoir in space. By studying the permeability of core plugs in different directions, we can better understand the spatial characteristics of the reservoir and provide a basis for the development of oil and gas production and reservoir protection strategies.

[0057] In the embodiment of the present invention, the first permeability is determined by:

[0058] The first permeability is calculated based on the viscosity and flow rate of the fluid used for testing, the length and cross-sectional area of ​​the saturated core plug, and the test pressure difference across the two ends of the saturated core plug.

[0059] Specifically, the first permeability can be calculated by Darcy's formula:

[0060]

[0061] Where K is the first permeability, in units of 10 -3 μm 2 ; Q is the flow rate of the fluid used for testing, in cm 3 / s; μ is the viscosity of the fluid used for testing, in mPa·s; the fluid used for testing can be oil or gas; L is the length of the saturated core plunger, in cm; A is the cross-sectional area of ​​the saturated core plunger, in cm 2 ; ΔP is the test pressure difference, unit is MPa.

[0062] S130, performing a working fluid damage test based on the angle of each saturated core plug to determine the second permeability of each saturated core plug after damage.

[0063] In the embodiment of the present invention, step S130 specifically includes:

[0064] The saturated core plungers are respectively installed into the holders of the corresponding drilling angles;

[0065] Under the same formation temperature and pressure conditions as those of the reservoir to be evaluated, damaging each of the saturated core plungers in the holder with a working fluid;

[0066] The second permeability of each of the saturated core plugs after damage is determined.

[0067] Specifically, core plungers saturated with formation water are respectively loaded into the corresponding position of the holders. The position of the holders must strictly correspond to the core drilling position, and all core holders must be installed on the same wellbore device. They are damaged with working fluid for a certain period of time under the same conditions as the formation temperature and pressure. The permeability of the damaged core plungers is tested to obtain the permeability of the damaged core plungers (i.e., the second permeability).

[0068] In an embodiment of the present invention, damaging each of the saturated core plungers in the holder with a working fluid comprises:

[0069] placing the holder in a closed environment and injecting a working fluid into the closed environment;

[0070] Stirring the working fluid by means of a stirring device;

[0071] The working fluid is heated to the temperature of the reservoir to be evaluated to cause damage for a preset time.

[0072] Specifically, the saturated core plunger is placed in the clamp, which is a clamping device with a 360° rotation function. While clamping the core, it can be rotated to the corresponding angle of the core. The clamp is placed in a closed environment, such as a glass cylinder, and the working fluid is added. The stirring system is turned on and heated to the reservoir temperature to simulate the real environment of the reservoir, and the working fluid damage is performed for a preset time.

[0073] In the embodiment of the present invention, the second permeability is determined by:

[0074] determining the post-damage flow rate of each of the saturated core plugs under standard test conditions;

[0075] The second permeability is determined based on the post-damage flow rate, the size of the saturated core plug, the environmental information under the standard test conditions, and the concentration of the working fluid.

[0076] The second permeability can also be calculated by Darcy's formula. The second permeability can be calculated by replacing the parameters in Darcy's formula accordingly. Specifically, the parameters introduced into the Darcy's formula described above are: K is the second permeability, the unit is 10 -3 μm 2 , Q is the flow rate of the fluid used for testing, in cm 3 / s; μ is the viscosity of the fluid used for testing, in mPa·s; L is the length of the saturated core plug, in cm; A is the cross-sectional area of ​​the saturated core plug, in cm 2 ; ΔP is the test pressure difference, unit is MPa.

[0077] S140: Determine the degree of damage of the reservoir to be evaluated at each of the angles based on the first permeability and the second permeability, and perform damage assessment based on the degree of damage.

[0078] In an embodiment of the present invention, determining the damage degree of the reservoir to be evaluated at each of the angles based on the first permeability and the second permeability includes:

[0079] For each angle of the saturated core plug, the damage degree is calculated by the following formula:

[0080]

[0081] Among them, R di is the degree of damage at angle i; K 0i is the first permeability of the saturated core plug at angle i, in units of 10 -3 μm 2 ; K di is the second permeability of the saturated core plug at angle i, in units of 10 -3 μm 2 .

[0082] By comparing the permeability of the core plug before and after damage, we can intuitively understand the damage of the working fluid to the reservoir, calculate the degree of damage, and quantitatively evaluate the degree of damage to the reservoir.

[0083] In the embodiment of the present invention, the damage situation is evaluated based on the damage degree, including:

[0084] Determine the strong damage direction and the weak damage direction according to the damage degree standard and the damage degree of each angle;

[0085] The damage direction is determined according to the strong damage direction and the weak damage direction.

[0086] The following is a detailed explanation of the solution of the embodiment of the present invention through a specific embodiment:

[0087] The design data of a certain well was collected to determine the formation mechanical parameters and the direction of wellbore advancement. Based on this data, downhole cores were drilled along the wellbore directions of 90°, 45°, 0°, -45° and -90°, and numbered 1, 2, 3, 4 and 5 respectively.

[0088] The core is dried and cleaned according to the above embodiment. Figure 2 Self-absorb formation water to establish initial water saturation;

[0089] Place 5 cores in the core holder of the working fluid damage assessment device and turn them to the corresponding angle. Then add the working fluid, turn on the stirring system, and heat to the reservoir temperature to simulate the real reservoir environment.

[0090] Under the conditions of confining pressure of 5 MPa and pressure difference of 2 MPa, the initial flow rates Q11, Q21, Q31, Q41 and Q51 of five cores were tested.

[0091] Three hours after the damage, the flow rates Q12, Q22, Q32, Q42 and Q52 of the five cores after damage were tested under the conditions of confining pressure of 5 MPa and pressure difference of 2 MPa.

[0092] The initial permeability and the permeability after damage of the core are calculated respectively by Darcy's formula in the above embodiment.

[0093] The damage degrees of the five cores are calculated according to the formula in the above embodiment. For example, the damage degrees are shown in the following table:

[0094]

[0095] Table 1: Damage degree of core plugs in different directions

[0096] As shown in Table 1, in horizontal well drilling, the reservoir working fluid damage has obvious spatial anisotropy, among which the core damage degree is the smallest at 90° relative to the wellbore direction, and the core damage degree is the largest at -90° in the wellbore direction. And the damage rate along the directions of 90°, 45°, 0°, -45° and -90° shows a gradual increase. Taking 0° (parallel to the bedding plane) as the standard, -45° and -90° are strong damage directions, and 90° and 45° are weak damage directions.

[0097] The solution of the embodiment of the present invention has at least the following advantages and improvements:

[0098] (1) The spatial anisotropy of reservoir damage during horizontal well drilling is fully considered. By evaluating the degree of damage of the working fluid to the core plungers in different spatial orientations, the reservoir damage is accurately evaluated, providing a strong theoretical basis for formulating reasonable reservoir protection strategies.

[0099] (2) The influence of well type on reservoir damage is taken into account. Therefore, this method is also applicable to the spatial anisotropy evaluation of reservoir damage in the deflection section of horizontal wells and has strong generalizability.

[0100] (3) The actual environment of the reservoir is comprehensively considered and the real environment of the reservoir is simulated. The test results can reflect the real situation of the reservoir and have a good guiding role in the actual engineering.

[0101] Embodiment 2

[0102] Figure 4 Schematic diagram of the structure of a device for evaluating the damage of working fluid in a tight oil and gas horizontal well provided by the second embodiment of the present invention. Figure 4 As shown, the device comprises:

[0103] The core drilling unit 410 is used to drill standard core plugs of different angles based on the direction of the reservoir formation to be evaluated, and to clean and dry them.

[0104] The first permeability determination unit 420 is used to determine the first permeability of the saturated core plug saturated with water of the standard core plug.

[0105] The second permeability determination unit 430 is used to perform a working fluid damage test based on the angle of each saturated core plug, and determine the second permeability of each saturated core plug after damage.

[0106] The damage degree determination unit 440 is used to determine the damage degree of the reservoir to be evaluated at each of the angles based on the first permeability and the second permeability, and to perform damage assessment based on the damage degree.

[0107] Optionally, the angle includes: parallel bedding and vertical bedding relative to the formation bedding and a preset angle formed with the formation bedding.

[0108] Optionally, the first permeability determination unit 420 is configured to execute:

[0109] The standard core plug is brought into contact with formation water and self-absorbed in a manner that the bedding plane is perpendicular to the water surface, thereby obtaining the saturated core plug;

[0110] The first permeability of the saturated core plug is determined.

[0111] Optionally, the first permeability determination unit 420 is configured to execute:

[0112] The first permeability is calculated based on the viscosity and flow rate of the fluid used for testing, the length and cross-sectional area of ​​the saturated core plug, and the test pressure difference across the two ends of the saturated core plug.

[0113] Optionally, the second permeability determination unit 430 is configured to execute:

[0114] The saturated core plungers are respectively installed into the holders of the corresponding drilling angles;

[0115] Under the same formation temperature and pressure conditions as those of the reservoir to be evaluated, damaging each of the saturated core plungers in the holder with a working fluid;

[0116] The second permeability of each of the saturated core plugs after damage is determined.

[0117] Optionally, the second permeability determining unit 430 is configured to determine the second permeability in the following manner:

[0118] The second permeability is calculated based on the viscosity and flow rate of the fluid used for testing after damage, the length and cross-sectional area of ​​the saturated core plug, and the test pressure difference across the saturated core plug.

[0119] Optionally, the second permeability determination unit 430 is configured to execute:

[0120] placing the holder in a closed environment and injecting a working fluid into the closed environment;

[0121] Stirring the working fluid by means of a stirring device;

[0122] The working fluid is heated to the temperature of the reservoir to be evaluated to cause damage for a preset time.

[0123] Optionally, the damage degree determination unit 440 is configured to execute:

[0124] For each angle of the saturated core plug, the damage degree is calculated by the following formula:

[0125]

[0126] Among them, R di is the degree of damage at angle i; K 0i is the first permeability of the saturated core plug at angle i, in units of 10 -3 μm 2 ; K di is the second permeability of the saturated core plug at angle i, in units of 10 -3 μm 2 .

[0127] Optionally, the damage degree determination unit 440 is configured to execute:

[0128] Determine the strong damage direction and the weak damage direction according to the damage degree standard and the damage degree of each angle;

[0129] The damage direction is determined according to the strong damage direction and the weak damage direction.

[0130] The device for evaluating the damage condition of working fluid in tight oil and gas horizontal wells provided in an embodiment of the present invention can execute the method for evaluating the damage condition of working fluid in tight oil and gas horizontal wells provided in any embodiment of the present invention, and has the corresponding functional modules and beneficial effects of the execution method.

[0131] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the present invention can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of the present invention can be achieved, and this document does not limit this.

[0132] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for evaluating the damage of working fluid in tight oil and gas horizontal wells, characterized in that: include: Drill standard core plugs at different angles based on the direction of the reservoir formation to be evaluated, and wash and dry them; determining a first permeability of a saturated core plug saturated with water of the standard core plug; Performing a working fluid damage test based on the angle of each saturated core plug to determine the second permeability of each saturated core plug after damage; The damage degree of the reservoir to be evaluated at each of the angles is determined based on the first permeability and the second permeability, and the damage condition is evaluated based on the damage degree.

2. The method according to claim 1, characterized in that The angles include: parallel bedding and vertical bedding relative to the stratum bedding and a preset angle formed with the stratum bedding.

3. The method according to claim 1, characterized in that The water-saturated core plug is obtained by self-imbibing the standard core plug in contact with formation water in a manner that the bedding plane is perpendicular to the water surface.

4. The method according to claim 3, characterized in that The first permeability is determined by: The first permeability is calculated based on the viscosity and flow rate of the fluid used for testing, the length and cross-sectional area of ​​the saturated core plug, and the test pressure difference across the two ends of the saturated core plug.

5. The method according to claim 1, characterized in that The method of performing a working fluid damage test based on the angle of each saturated core plug to determine the second permeability of the damaged saturated core plug includes: The saturated core plungers are respectively installed into the holders of the corresponding drilling angles; Under the same formation temperature and pressure conditions as those of the reservoir to be evaluated, damaging each of the saturated core plungers in the holder with a working fluid; The second permeability of each of the saturated core plugs after damage is determined.

6. The method according to claim 5, characterized in that The second permeability is determined by: The second permeability is calculated based on the viscosity and flow rate of the fluid used for testing after damage, the length and cross-sectional area of ​​the saturated core plug, and the test pressure difference across the saturated core plug.

7. The method according to claim 5, characterized in that The damaging of each of the saturated core plungers in the holder with the working fluid comprises: placing the holder in a closed environment and injecting a working fluid into the closed environment; Stirring the working fluid by means of a stirring device; The working fluid is heated to the temperature of the reservoir to be evaluated to cause damage for a preset time.

8. The method according to claim 1, characterized in that The determining the damage degree of the reservoir to be evaluated at each of the angles based on the first permeability and the second permeability includes: For each angle of the saturated core plug, the damage degree is calculated by the following formula: Among them, R di is the degree of damage at angle i; K 0i is the first permeability of the saturated core plug at angle i, in units of 10 -3 μm 2 ; K di is the second permeability of the saturated core plug at angle i, in units of 10 -3 μm 2 .

9. The method according to claim 1, characterized in that: The damage assessment based on the damage extent includes: Determine the strong damage direction and the weak damage direction according to the damage degree standard and the damage degree of each angle; The damage direction is determined according to the strong damage direction and the weak damage direction.

10. A device for evaluating the damage of working fluid in a tight oil and gas horizontal well, characterized in that: include: The core drilling unit is used to drill standard core plugs at different angles based on the direction of the reservoir formation to be evaluated and to clean and dry them; A first permeability determination unit, used to determine a first permeability of a saturated core plug saturated with water of the standard core plug; A second permeability determination unit, configured to perform a working fluid damage test based on the angle of each saturated core plug, and determine a second permeability of each saturated core plug after damage; A damage degree determination unit is used to determine the damage degree of the reservoir to be evaluated at each of the angles based on the first permeability and the second permeability, and to perform damage assessment based on the damage degree.

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