阅读说明：本技术 一种评价致密页岩储层的入井流体的优选方法 (Optimization method for evaluating well-entering fluid of tight shale reservoir ) 是由 谭晓华 陈昌浩 李晓平 李溢龙 漆麟 万翠蓉 王一航 丁磊 李劲涵 王宁 于 2021-10-15 设计创作，主要内容包括：本发明涉及一种评价致密页岩储层的入井流体的优选方法,属于油气田开发领域；本发明通过四种不同配方的入井流体作用页岩储层后,通过研究储层微观结构特征和矿物组分的改变以及宏观孔渗值的改变,进行储层评价,优选与储层适应的入井流体；其技术方案是：将配制好的不同入井流体对岩样进行浸泡和驱替实验,采用X射线衍射、扫描电镜测试、基础孔渗测试结果,对储层岩样分别进行微观和宏观评价,并将微观与宏观评价结果结合进行综合评价,优选出与页岩储层适应的入井流体。与现有技术相比,本发明具有评价体系有效性强,多重评价,说服性强,可推广性强。(The invention relates to a preferable method for evaluating a well entering fluid of a tight shale reservoir, belonging to the field of oil and gas field development; after the shale reservoir is acted by the working fluid with four different formulas, reservoir evaluation is carried out by researching the microstructure characteristics of the reservoir, the change of mineral components and the change of macroscopic pore permeability value, and the working fluid adaptive to the reservoir is optimized; the technical scheme is as follows: soaking and displacing the prepared different well-entering fluids to the rock sample, respectively carrying out microscopic evaluation and macroscopic evaluation on the reservoir rock sample by adopting X-ray diffraction, scanning electron microscope test and basic pore infiltration test results, and carrying out comprehensive evaluation by combining the microscopic evaluation result and the macroscopic evaluation result to preferably select the well-entering fluid adaptive to the shale reservoir. Compared with the prior art, the method has the advantages of strong evaluation system effectiveness, multiple evaluations, strong persuasion and strong popularization.)

1. A preferred method of evaluating a well fluid for tight shale reservoirs, the method comprising the steps of:

s100, drilling four shale reservoir rock samples of the same block and different layers, drying the shale reservoir rock samples after carrying out standardized processing on the shale reservoir rock samples, and measuring the porosity of the shale reservoir rock samples through gasf ₁Measuring permeability of shale reservoir by gask ₁；

S200, cutting a slice with the thickness of 1cm of the shale reservoir rock sample subjected to gas detection along the cross section of the port, and performing in-situ scanning electron microscope and X-ray diffraction experiments to determine the fracture width of the shale reservoir rock sample of the original stratumL ₁Pore diameterD ₁And clay mineral contentW ₁；

S300, preparing four well entry fluids of water-reducing water containing an organic anti-swelling agent, water-reducing water without the organic anti-swelling agent, guanidine gum liquid containing the organic anti-swelling agent and guanidine gum liquid without the organic anti-swelling agent, and standing for 24 hours to automatically break the gel;

s400, vacuumizing the dried shale reservoir rock sample for 12 hours, and pressurizing 15MPa saturated crude oil for 12 hours;

s500, respectively displacing four shale reservoir rock samples saturated by crude oil by using the prepared water reducing and blocking agent containing the organic anti-swelling agent, the water reducing and blocking agent not containing the organic anti-swelling agent, the guanidine gum liquid containing the organic anti-swelling agent and the guanidine gum liquid not containing the organic anti-swelling agent until the solution is expelled;

s600, cutting a slice with the thickness of 1cm of the shale reservoir rock sample after displacement along the section of the port which is cut for the first time, performing in-situ scanning electron microscope and X-ray diffraction experiments, and determining the width of the crack of the shale reservoir rock sample of the stratum after the displacement of the fluid entering the wellL ₂Pore diameterD ₂And clay mineral contentW ₂Calculating the change value of the width of the crack before and after the entering of the well fluidLCalculating the diameter change value of the pore before and after the entering of the well fluidDCalculating the change value of the clay mineral content before and after the entering of the well fluidWBringing the calculation result into the shale reservoir microscopic evaluation coefficientIPerforming shale reservoir microscopic evaluation;

in the formula (I), the compound is shown in the specification,Ithe shale reservoir microscopic evaluation coefficient is a dimensionless quantity;Lthe calculation formula is that the change value of the width of the crack before and after the entering of the well fluid isNo dimensional quantity;Dfor the change value of the pore diameter before and after the entering of the well fluid, the calculation formula isNo dimensional quantity;Wthe change value of the clay mineral content before and after the entry of the well fluidNo dimensional quantity;

when in useIWhen the damage is less than or equal to-1, the fluid entering the well has severe damage to the shale reservoirWeighing; when-1 is less than or equal toIWhen the surface area is less than 0, the fluid entering the well slightly damages the shale reservoir; when in useIWhen the value is not less than 0, the fluid entering the well has no improvement on the shale reservoir; when 0 <IWhen the water content is less than or equal to 1, the improvement effect of the well entry fluid on the shale reservoir is weak; when in useIWhen the pressure is more than or equal to 1, the improvement effect of the fluid entering the well on the shale reservoir is good;

s700, measuring the porosity of the shale reservoir rock sample after displacement by using the weighing method againf ₂Measuring the permeability of the shale reservoir through the crude oilk ₂Calculating the change value of the porosity of the shale reservoir rock sample before and after the well entry fluid displacementFCalculating the change value of the permeability of the shale reservoir rock sample before and after the well entry fluid displacementKBringing the calculation result into a shale reservoir macroscopic evaluation coefficientY，

Performing macroscopic evaluation on the shale reservoir;

in the formula (I), the compound is shown in the specification,Ythe method is characterized in that the method is a macroscopic evaluation coefficient of the shale reservoir and has no dimensional quantity;Fthe calculation formula is that the change value of the porosity of the shale reservoir rock sample before and after the well entering fluid displacement isIn units%;Kin order to calculate the change value of the permeability of the shale reservoir rock sample before and after the well fluid displacement, the calculation formula isThe unit mD;

when in useYWhen the damage rate is less than or equal to-1, the fluid entering the well seriously damages the shale reservoir; when-1 is less than or equal toYWhen the surface area is less than 0, the fluid entering the well slightly damages the shale reservoir; when in useYWhen the value is not less than 0, the fluid entering the well has no improvement on the shale reservoir; when 0 <YWhen the water content is less than or equal to 1, the improvement effect of the well entry fluid on the shale reservoir is weak; when in useYWhen the pressure is more than or equal to 1, the improvement effect of the fluid entering the well on the shale reservoir is good;

s800, based on the experiment of displacing the shale reservoir rock sample by four different well-entering fluids, calculatingMicroscopic evaluation coefficient of shale reservoirIAnd the calculated shale reservoir macroscopic evaluation coefficientYSubstituting into shale reservoir comprehensive evaluation coefficientGEvaluating the condition of the shale reservoir by different well entering fluids, thereby preferably selecting the well entering fluid which is suitable for the reservoir;

in the formula (I), the compound is shown in the specification,Gthe comprehensive evaluation coefficient of the shale reservoir is a dimensionless quantity;Ythe method is characterized in that the method is a macroscopic evaluation coefficient of the shale reservoir and has no dimensional quantity;Ithe evaluation coefficient is improved for the shale reservoir microcosmic, and dimension is not included;

when in useGWhen the surface area is less than 0, the fluid entering the well damages the shale reservoir; when in useGWhen the value is not less than 0, the fluid entering the well has no improvement on the shale reservoir; when in useGWhen the pressure is higher than 0, the fluid entering the well has an improvement on the shale reservoir;

s900, calculating the comprehensive evaluation coefficient of the shale reservoirGPreferably a well fluid for shale reservoir improvement.

2. A preferred method of evaluating a well fluid for tight shale reservoirs according to claim 1, wherein: the anti-drag water containing the organic anti-swelling agent comprises the following components in percentage by mass: 0.08 percent of drag reducer, 0.5 percent of organic anti-swelling agent, 0.1 percent of synergist, 0.02 percent of bactericide and 0.01 percent of ammonium persulfate; the anti-drag water without the organic anti-swelling agent comprises the following components in percentage by mass: 0.08 percent of drag reducer, 0.1 percent of synergist, 0.02 percent of bactericide and 0.01 percent of ammonium persulfate; the guanidine gum liquid containing the organic anti-swelling agent comprises the following components in percentage by mass: 0.35 percent of guanidine gum, 0.5 percent of organic anti-swelling agent, 0.025 percent of cleanup additive, 0.025 percent of sodium hydroxide, 0.02 percent of bactericide and 5 percent of cross-linking liquid.

Technical Field

The invention belongs to the field of oil and gas field development, and particularly relates to a preferable method for evaluating a well entering fluid of a compact shale reservoir.

Background

Since the first discovery of oil and gas resources as fuel, the conventional oil and gas resources face huge exploitation pressure as the exploration and development of the conventional oil and gas reservoirs are fully developed and the exploitation and use amount is larger and larger during the second energy revolution. Therefore, with the great success of the shale gas revolution in the United states, the oil and gas energy pattern in China is promoted to generate great changes. With the progress of exploration technology, China finds huge compact oil and gas resources, wherein the exploration reserves of shale oil and gas are huge, but the exploitation difficulty is increased. The shale oil and gas reservoir belongs to a typical low-porosity and low-permeability reservoir, and has poor fracture development and poor liquidity. Thus, to achieve large-scale industrial exploitation, fracturing modifications must be made to form the productive zone. The application of fracturing technology is a great progress in the exploration of oil and gas resources, but the problem of reservoir damage caused by the fracturing technology becomes a very serious problem. Due to the complexity and the particularity of the components of the shale gas reservoir, the property of the reservoir is very easily influenced by external fluid, so that secondary damage is caused to the reservoir, and the exploitation cost and the exploitation difficulty are increased. In the face of such severe problems, it is urgently needed to find a well fluid adaptive to the shale gas reservoir, so as to reduce the damage degree of the reservoir.

At present, the research on the well entry fluid of an unconventional oil and gas reservoir still stays in the influence of a single fluid on a reservoir, and rarely simultaneously, different well entry fluids are applied to the same reservoir to carry out experiments, so that the well entry fluid adaptive to the reservoir is preferably selected, the aims of reducing the damage of the reservoir and reducing the loss of the reservoir are fulfilled, the aim of improving the seepage environment of the shale gas reservoir is fulfilled, and the preferable method for evaluating the well entry fluid of the compact shale reservoir is obtained.

Disclosure of Invention

The invention aims to: the method aims to solve the problems that solid phase and liquid phase damage is caused to a reservoir after shale oil and gas is subjected to fracturing, and after a well entering fluid enters the reservoir, pore blocking of the reservoir is caused, the connectivity of pore throats is reduced, the permeability of the reservoir is reduced, and the oil and gas output is reduced. According to the method, by using modern scientific and technical means such as a field emission scanning electron microscope and an X-ray diffraction experiment, macroscopic pore permeability parameter change, microscopic pore space and rock sample clay mineral content change after different working fluids act on the shale reservoir are compared, macroscopic data change rate and microscopic structure change rate are calculated and are respectively brought into a macroscopic evaluation coefficient and a microscopic evaluation coefficient, and finally, the comprehensive evaluation of the shale reservoir by four different fluids is carried out by combining the macroscopic evaluation coefficient and the microscopic evaluation coefficient, so that the working fluid adaptive to the shale gas reservoir is optimized, the damage of the reservoir is reduced after the working fluid enters the reservoir, the liquidity of the reservoir is improved, and the recovery ratio of the shale oil gas reservoir is improved.

In order to achieve the above object, the present invention provides a preferable method for evaluating a well fluid of a tight shale gas reservoir, the method comprising the steps of:

s100, drilling four shale reservoir rock samples of the same block and different layers, drying the shale reservoir rock samples after carrying out standardized processing on the shale reservoir rock samples, and measuring the porosity of the shale reservoir rock samples through gasf ₁Measuring permeability of shale reservoir by gask ₁；

S200, cutting a slice with the thickness of 1cm of the shale reservoir rock sample subjected to gas detection along the cross section of the port, and performing in-situ scanning electron microscope and X-ray diffraction experiments to determine the fracture width of the shale reservoir rock sample of the original stratumL ₁Pore diameterD ₁And clay mineral contentW ₁；

S300, preparing four well entry fluids of water-reducing water containing an organic anti-swelling agent, water-reducing water without the organic anti-swelling agent, guanidine gum liquid containing the organic anti-swelling agent and guanidine gum liquid without the organic anti-swelling agent, and standing for 24 hours to automatically break the gel;

s400, vacuumizing the dried shale reservoir rock sample for 12 hours, and pressurizing 15MPa saturated crude oil for 12 hours;

s500, respectively displacing four shale reservoir rock samples saturated by crude oil by using the prepared water reducing and blocking agent containing the organic anti-swelling agent, the water reducing and blocking agent not containing the organic anti-swelling agent, the guanidine gum liquid containing the organic anti-swelling agent and the guanidine gum liquid not containing the organic anti-swelling agent until the solution is expelled;

s600, cutting a slice with the thickness of 1cm of the shale reservoir rock sample after displacement along the section of the port which is cut for the first time, performing in-situ scanning electron microscope and X-ray diffraction experiments, and determining the width of the crack of the shale reservoir rock sample of the stratum after the displacement of the fluid entering the wellL ₂Pore diameterD ₂And clay mineral contentW ₂Calculating the change value of the width of the crack before and after the entering of the well fluidLCalculating the diameter change value of the pore before and after the entering of the well fluidDCalculating the change value of the clay mineral content before and after the entering of the well fluidWBringing the calculation result into the shale reservoir microscopic evaluation coefficientIPerforming shale reservoir microscopic evaluation;

in the formula (I), the compound is shown in the specification,Ithe shale reservoir microscopic evaluation coefficient is a dimensionless quantity;Lthe calculation formula is that the change value of the width of the crack before and after the entering of the well fluid isNo dimensional quantity;Dfor the change value of the pore diameter before and after the entering of the well fluid, the calculation formula isNo dimensional quantity;Wthe change value of the clay mineral content before and after the entry of the well fluidNo dimensional quantity;

when in useIWhen the damage rate is less than or equal to-1, the fluid entering the well seriously damages the shale reservoir; when-1 is less than or equal toIWhen the surface area is less than 0, the fluid entering the well slightly damages the shale reservoir; when in useIWhen the value is not less than 0, the fluid entering the well has no improvement on the shale reservoir; when 0 <IWhen the water content is less than or equal to 1, the improvement effect of the well entry fluid on the shale reservoir is weak; when in useIWhen the pressure is more than or equal to 1, the improvement effect of the fluid entering the well on the shale reservoir is good;

s700, measuring the porosity of the shale reservoir rock sample after displacement by using the weighing method againf ₂Measuring the permeability of the shale reservoir through the crude oilk ₂Calculating the change value of the porosity of the shale reservoir rock sample before and after the well entry fluid displacementFCalculating the change value of the permeability of the shale reservoir rock sample before and after the well entry fluid displacementKBringing the calculation result into a shale reservoir macroscopic evaluation coefficientY，

Performing macroscopic evaluation on the shale reservoir;

in the formula (I), the compound is shown in the specification,Ythe method is characterized in that the method is a macroscopic evaluation coefficient of the shale reservoir and has no dimensional quantity;Fthe calculation formula is that the change value of the porosity of the shale reservoir rock sample before and after the well entering fluid displacement isIn units%;Kin order to calculate the change value of the permeability of the shale reservoir rock sample before and after the well fluid displacement, the calculation formula isThe unit mD;

when in useYWhen the damage rate is less than or equal to-1, the fluid entering the well seriously damages the shale reservoir; when-1 is less than or equal toYWhen the surface area is less than 0, the fluid entering the well slightly damages the shale reservoir; when in useYWhen the value is not less than 0, the fluid entering the well has no improvement on the shale reservoir; when 0 <YWhen the water content is less than or equal to 1, the improvement effect of the well entry fluid on the shale reservoir is weak; when in useYWhen the pressure is more than or equal to 1, the improvement effect of the fluid entering the well on the shale reservoir is good;

s800, based on four different well entering fluids, displacing pagePerforming experiment on rock samples of the rock reservoir according to the calculated microscopic evaluation coefficient of the shale reservoirIAnd the calculated shale reservoir macroscopic evaluation coefficientYSubstituting into shale reservoir comprehensive evaluation coefficientGEvaluating the condition of the shale reservoir by different well entering fluids, thereby preferably selecting the well entering fluid which is suitable for the reservoir;

in the formula (I), the compound is shown in the specification,Gthe comprehensive evaluation coefficient of the shale reservoir is a dimensionless quantity;Ythe method is characterized in that the method is a macroscopic evaluation coefficient of the shale reservoir and has no dimensional quantity;Ithe evaluation coefficient is improved for the shale reservoir microcosmic, and dimension is not included;

when in useGWhen the surface area is less than 0, the fluid entering the well damages the shale reservoir; when in useGWhen the value is not less than 0, the fluid entering the well has no improvement on the shale reservoir; when in useGWhen the pressure is higher than 0, the fluid entering the well has an improvement on the shale reservoir;

s900, calculating the comprehensive evaluation coefficient of the shale reservoirGPreferably a well fluid for shale reservoir improvement.

The preferable method for improving the well-entering fluid of the compact shale gas reservoir is characterized by comprising the following steps: the anti-drag water containing the organic anti-swelling agent comprises the following components in percentage by mass: 0.08 percent of drag reducer, 0.5 percent of organic anti-swelling agent, 0.1 percent of synergist, 0.02 percent of bactericide and 0.01 percent of ammonium persulfate; the anti-drag water without the organic anti-swelling agent comprises the following components in percentage by mass: 0.08 percent of drag reducer, 0.1 percent of synergist, 0.02 percent of bactericide and 0.01 percent of ammonium persulfate; the guanidine gum liquid containing the organic anti-swelling agent comprises the following components in percentage by mass: 0.35 percent of guanidine gum, 0.5 percent of organic anti-swelling agent, 0.025 percent of cleanup additive, 0.025 percent of sodium hydroxide, 0.02 percent of bactericide and 5 percent of cross-linking liquid.

Compared with the prior art, the invention has the following beneficial effects: (1) the evaluation system is simple and effective; (2) the results are more convincing through multiple evaluations; (3) the popularization is strong.

Drawings

In the drawings:

FIG. 1 is a technical scheme of the method.

FIG. 2 is a scanning electron micrograph of an original rock sample Y-1.

FIG. 3 is a scanning electron micrograph of an original rock sample Y-2.

FIG. 4 is a scanning electron micrograph of an original rock sample Y-3.

FIG. 5 is a scanning electron micrograph of an original rock sample Y-4.

FIG. 6 is an X-ray diffraction pattern of the original rock sample Y-1.

FIG. 7 is an X-ray diffraction pattern of the original rock sample Y-2.

FIG. 8 is an X-ray diffraction pattern of the original rock sample Y-3.

FIG. 9 is an X-ray diffraction pattern of the original rock sample Y-4.

FIG. 10 is a scanning electron micrograph of Y-1 after immersion in well fluid.

FIG. 11 is a scanning electron micrograph of Y-2 after immersion in well fluid.

FIG. 12 is a scanning electron micrograph of Y-3 after immersion in well fluid.

FIG. 13 is a scanning electron micrograph of Y-4 after immersion in well fluid.

FIG. 14 is an X-ray diffraction pattern of Y-1 after a well fluid soak.

FIG. 15 is an X-ray diffraction pattern of Y-2 after a well fluid soak.

FIG. 16 is an X-ray diffraction pattern of Y-3 after a well fluid soak.

FIG. 17 is an X-ray diffraction pattern of Y-4 after a well fluid soak.

Detailed Description

The present invention will be further described with reference to the following embodiments and drawings.

The invention provides a preferable method for improving a well entry fluid of a tight shale gas reservoir, and FIG. 1 is a technical scheme diagram of the method, and the method comprises the following steps:

firstly, shale reservoir rock cores Y-1, Y-2, Y-3 and Y-4 with the same layer are obtained, and the porosity of the shale reservoir rock core is measured through gas after the shale reservoir rock core is driedf ₁And permeability valuek ₁；

TABLE 1

Secondly, cutting a slice with the thickness of 1cm from the shale reservoir rock sample after gas detection along the cross section of the port, and performing an in-situ scanning electron microscope and an X-ray diffraction experiment, wherein the scanning electron microscope images of the original rock samples of Y-1, Y-2, Y-3 and Y-4 are shown in figures 2, 3, 4 and 5, and the X-ray diffraction patterns of the original rock samples of Y-1, Y-2, Y-3 and Y-4 are shown in figures 6, 7, 8 and 9, so as to determine the fracture width of the original stratum shale reservoir rock sampleL ₁Pore diameterD ₁And clay mineral contentW ₁；

TABLE 2

Thirdly, preparing four kinds of well entering fluids including the water reducing water containing the organic anti-swelling agent, the water reducing water without the organic anti-swelling agent, the guanidine gum liquid containing the organic anti-swelling agent and the guanidine gum liquid without the organic anti-swelling agent, and standing for 24 hours to automatically break the gel. The formula of the water-reducing agent containing the organic anti-swelling agent is shown in Table 3, the formula of the water-reducing agent not containing the organic anti-swelling agent is shown in Table 4, the formula of the guanidine gum solution containing the organic anti-swelling agent is shown in Table 5, and the formula of the guanidine gum solution not containing the organic anti-swelling agent is shown in Table 6;

TABLE 3

TABLE 4

TABLE 5

TABLE 6

Fourthly, vacuumizing the dried shale reservoir rock sample for 12 hours, and pressurizing 15MPa saturated crude oil for 12 hours;

fifthly, respectively displacing four shale reservoir rock samples saturated by crude oil by utilizing the prepared water reducing and blocking agent containing the organic anti-swelling agent, the water reducing and blocking agent not containing the organic anti-swelling agent, the guanidine gum liquid containing the organic anti-swelling agent and the guanidine gum liquid not containing the organic anti-swelling agent until the solution is expelled;

sixthly, cutting a slice with the thickness of 1cm from the shale reservoir rock sample after displacement along the cross section of the port cut at the last time, and performing an in-situ scanning electron microscope and X-ray diffraction experiment, wherein the scanning electron microscope images of the rock sample after the soaking of the well entering fluids of Y-1, Y-2, Y-3 and Y-4 are shown in figures 10, 11, 12 and 13, and the X-ray diffraction spectra of the rock sample after the soaking of the well entering fluids of Y-1, Y-2, Y-3 and Y-4 are shown in figures 14, 15, 16 and 17, so as to determine the fracture width of the shale reservoir rock sample after the displacement of the well entering fluidsL ₂Pore diameterD ₂And clay mineral contentW ₂The test results are shown in the following table;

TABLE 7

Seventhly, calculating the change value of the width of the crack before and after the entering of the well fluid according to the experimental test resultLCalculating the diameter change value of the pore before and after the entering of the well fluidDCalculating the change value of the clay mineral content before and after the entering of the well fluidWThe calculation results are shown in the following table;

TABLE 8

Eighthly, bringing the calculation result into a shale reservoir microscopic evaluation coefficientITo make shaleMicroscopic evaluation of a reservoir;

in the formula (I), the compound is shown in the specification,Ithe shale reservoir microscopic evaluation coefficient is a dimensionless quantity;Lthe calculation formula is that the change value of the width of the crack before and after the entering of the well fluid isNo dimensional quantity;Dfor the change value of the pore diameter before and after the entering of the well fluid, the calculation formula isNo dimensional quantity;Wthe change value of the clay mineral content before and after the entry of the well fluidNo dimensional quantity;

when in useIWhen the damage rate is less than or equal to-1, the fluid entering the well seriously damages the shale reservoir; when-1 is less than or equal toIWhen the surface area is less than 0, the fluid entering the well slightly damages the shale reservoir; when in useIWhen the value is not less than 0, the fluid entering the well has no improvement on the shale reservoir; when 0 <IWhen the water content is less than or equal to 1, the improvement effect of the well entry fluid on the shale reservoir is weak; when in useIWhen the pressure is more than or equal to 1, the improvement effect of the fluid entering the well on the shale reservoir is good;

TABLE 9

The tested calculation results show that after different well entering fluids enter the shale reservoir, the shale reservoir is subjected to microscopic evaluation coefficient comparison, and different well entering fluids are found to have different degrees of damage to the shale reservoir, the most serious damage is a rock sample soaked by guanidine gum without an organic anti-swelling agent, and the least damaged is shale soaked by anti-drag water containing the anti-swelling agent;

ninthly, measuring the porosity of the shale reservoir rock sample after displacement by using the weighing method againf ₂Measuring the permeability of the shale reservoir through the crude oilk ₂Calculating the change value of the porosity of the shale reservoir rock sample before and after the well entry fluid displacementFCalculating the change value of the permeability of the shale reservoir rock sample before and after the well entry fluid displacementKThe calculation results are shown below;

watch 10

Ninth, the calculation result is brought into a shale reservoir macroscopic evaluation coefficientYPerforming macroscopic evaluation on the shale reservoir;

in the formula (I), the compound is shown in the specification,Ythe method is characterized in that the method is a macroscopic evaluation coefficient of the shale reservoir and has no dimensional quantity;Fthe calculation formula is that the change value of the porosity of the shale reservoir rock sample before and after the well entering fluid displacement isIn units%;Kin order to calculate the change value of the permeability of the shale reservoir rock sample before and after the well fluid displacement, the calculation formula isThe unit mD;

when in useYWhen the damage rate is less than or equal to-1, the fluid entering the well seriously damages the shale reservoir; when-1 is less than or equal toYWhen the surface area is less than 0, the fluid entering the well slightly damages the shale reservoir; when in useYWhen the value is not less than 0, the fluid entering the well has no improvement on the shale reservoir; when 0 <YWhen the water content is less than or equal to 1, the improvement effect of the well entry fluid on the shale reservoir is weak; when in useYWhen the pressure is more than or equal to 1, the improvement effect of the fluid entering the well on the shale reservoir is good;

TABLE 11

Measuring basic pore permeability of rock samples before and after different well entering fluids are displaced, and performing macroscopic evaluation on the shale reservoir according to a calculation result, wherein the evaluation result shows that the guar gum without the organic anti-swelling agent has the most serious damage on the shale reservoir and the drag reduction water containing the organic anti-swelling agent has the least damage on the shale reservoir;

tenthly, based on the experiment of displacing the shale reservoir rock sample by four different well-entering fluids, according to the calculated microscopic improvement evaluation coefficient of the shale reservoirIAnd the calculated shale reservoir macroscopic improvement evaluation coefficientYSubstituting the comprehensive coefficient into shale reservoir stratum to improve and evaluateGEvaluating the improvement condition of the shale reservoir by different well entering fluids, so as to preferably select the well entering fluid adaptive to the reservoir;

in the formula (I), the compound is shown in the specification,Gcomprehensive coefficients are improved and evaluated for the shale reservoir, and dimension is not needed;Ythe evaluation coefficient is macroscopically improved for the shale reservoir, and the dimensionless quantity is avoided;Ithe evaluation coefficient is improved for the shale reservoir microcosmic, and dimension is not included;

when in useGWhen the surface area is less than 0, the fluid entering the well damages the shale reservoir; when in useGWhen the value is not less than 0, the fluid entering the well has no improvement on the shale reservoir; when in useGWhen the pressure is higher than 0, the fluid entering the well has an improvement on the shale reservoir;

s900, evaluating comprehensive coefficient through calculated shale reservoir improvementGPreferably a well fluid for shale reservoir improvement;

TABLE 12

Combining the microscopic evaluation coefficient and the macroscopic evaluation coefficient of the shale reservoir, calculating the comprehensive evaluation coefficient of the shale reservoir, and obtaining the calculation result that the damage degree of the guanidine gum without the organic anti-swelling agent to the shale reservoir is larger than that of the drag reduction water without the organic anti-swelling agent than that of the guanidine gum with the organic anti-swelling agent, and the damage to the shale reservoir is the drag reduction water with the organic anti-swelling agent, so that the drag reduction water with the organic anti-swelling agent is preferably selected to be the entry fluid of the shale reservoir through the evaluation of the effect of different entry fluids and the shale reservoir.

Further, the shale reservoir microscopic evaluation, the shale reservoir macroscopic evaluation and the evaluation of the shale reservoir comprehensive coefficient are carried out.

Compared with the prior art, the invention has the following beneficial effects: (1) the evaluation system is simple and effective; (2) the results are more convincing through multiple evaluations; (3) the popularization is strong.

Finally, it should be noted that: although the present invention has been described in detail with reference to the above embodiments, it should be understood by those skilled in the art that: modifications and equivalents may be made thereto without departing from the spirit and scope of the invention and it is intended to cover in the claims the invention as defined in the appended claims.