A method for predicting effectiveness of overburden shale cap rock on drilling targets for oil and gas reservoirs

Abstract

The application provides a method for predicting effectiveness of a shale cap rock over a drilling target of an oil and gas reservoir. The method takes measured displacement pressure of the shale cap rock as a starting point, obtains quantitative threshold thickness data of the shale cap rock according to mutual correlation among burial depth, thickness and sealing property of the shale cap rock through regression and fitting, and then accurately predicts effectiveness of the shale cap rock over the drilling target of the oil and gas reservoir, thereby providing a basis for drilling of the oil and gas reservoir.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of cap rock evaluation of oil and gas reservoir drilling, and particularly relates to a method for predicting effectiveness of overlying argillaceous rock cap rock of oil and gas reservoir drilling target. BACKGROUND

[0002] Cap rock refers to an impermeable layer or a low permeable layer located above a reservoir and capable of preventing oil and gas in the reservoir from spreading upward. Previous statistical studies show that 70% of overlying cap rocks of oil and gas reservoirs are argillaceous rocks, including mudstone, mud shale, silty mudstone, calcareous mudstone, gypsiferous mudstone, etc. The research on oil and gas reservoir drilling target needs to evaluate and predict from four reservoir-forming elements, i.e. oil and gas source, reservoir space, structural trap and overlying cap rock. At present, a large amount of systematic research work from qualitative to quantitative and from pre-drilling prediction to post-drilling evaluation has been accumulated for the first three reservoir-forming elements, i.e. oil and gas source, reservoir space and structural trap, while systematic research on the fourth reservoir-forming element, i.e. overlying cap rock, is still relatively less.

[0003] At present, there are mainly two methods for predicting overlying argillaceous rock cap rock of oil and gas reservoir:

[0004] The first method is to analyze petrological characteristics of overlying argillaceous rock cap rock of discovered oil and gas reservoir, and predict distribution rule of argillaceous rock cap rock in combination with sedimentary rule of strata in the region, but this rule-based research method is difficult to quantitatively determine the sealing capacity of cap rock, and its essence is only to obtain the distribution rule of argillaceous rock, but cannot exactly predict whether the argillaceous rock has sealing capacity;

[0005] The second method is to collect core samples of argillaceous rock cap rock for testing to obtain displacement pressure (also known as breakthrough pressure, which refers to resistance that needs to be overcome by gas to displace water-saturated core) of argillaceous rock, so as to obtain quantitative data of sealing capacity of argillaceous rock (patent "displacement pressure measuring device for gas storage cap rock", publication number CN203479636U). However, since core samples can only be obtained from existing drilling data, this method is difficult to predict sealing capacity of cap rock of un-drilled target, and can only provide reference for drilling target as "precedent" beside the well, and cannot provide direct basis for oil and gas reservoir drilling target. SUMMARY

[0006] In view of the above problems, the present application provides a method for predicting effectiveness of overlying argillaceous rock cap rock of oil and gas reservoir drilling target, which overcomes the above problems or at least partially solves the above problems.

[0007] To solve the above technical problems, the present application provides a method for predicting effectiveness of overlying argillaceous rock cap rock of oil and gas reservoir drilling target, which comprises the following steps:

[0008] acquiring a depth and a thickness of the overlying shale cap rock of the drilled well according to basic data of the drilled well in the target area;

[0009] sampling cores of the overlying shale cap rock and obtaining a displacement pressure test value;

[0010] acquiring a displacement pressure threshold value calculation formula according to the thickness and the displacement pressure test value;

[0011] acquiring a cap rock depth and cap rock displacement pressure correlation formula according to the depth and the displacement pressure test value;

[0012] acquiring a cap rock thickness threshold value calculation formula according to the displacement pressure threshold value calculation formula and the cap rock depth and cap rock displacement pressure correlation formula;

[0013] calculating a threshold thickness and an actual thickness of the overlying shale cap rock of the oil and gas reservoir drilling target according to position data of the oil and gas reservoir drilling target and seismic response characteristics of sandstone layers and shale layers in the target area, and judging whether the overlying shale cap rock of the oil and gas reservoir drilling target is an invalid cap rock.

[0014] Preferably, the basic data includes one or more of logging data, core data, well logging curve data, and oil testing data of the drilled well.

[0015] Preferably, acquiring the depth and the thickness of the overlying shale cap rock of the drilled well includes determining a position of an oil and gas layer of the drilled well in the drilled well through logging data, core data, well logging curve data, and oil testing data in the basic data to acquire the depth and the thickness of the oil and gas layer.

[0016] Preferably, the sampling cores of the overlying shale cap rock and obtaining a displacement pressure test value includes steps of:

[0017] acquiring positions of all oil and gas layers in the drilled well;

[0018] acquiring depths of overlying shale cap rocks of all the oil and gas layers;

[0019] sampling cores of the overlying shale cap rocks corresponding to all the oil and gas layers according to the depths;

[0020] performing displacement pressure tests on all the cores and obtaining the displacement pressure test values.

[0021] Preferably, the acquiring a displacement pressure threshold value calculation formula according to the thickness and the displacement pressure test value includes steps of:

[0022] acquiring thicknesses of all the overlying shale cap rocks and the displacement pressure test values corresponding thereto;

[0023] a first scatter plot of all the thicknesses and all the corresponding displacement pressure test values is plotted;

[0024] envelope regression is performed on the first scatter plot;

[0025] a displacement pressure threshold value calculation formula is obtained.

[0026] Preferably, the obtaining a caprock depth-displacement pressure correlation formula according to the depth and the displacement pressure test value comprises the steps of:

[0027] the depth of all the overlying shale caprocks and the corresponding displacement pressure test values are obtained;

[0028] a second scatter plot of all the thicknesses and all the corresponding displacement pressure test values is plotted;

[0029] correlation regression is performed on the second scatter plot;

[0030] a caprock depth-displacement pressure correlation formula is obtained.

[0031] Preferably, the obtaining a caprock thickness threshold value calculation formula according to the displacement pressure threshold value calculation formula and the caprock depth-displacement pressure correlation formula comprises the steps of:

[0032] the displacement pressure threshold value calculation formula is obtained;

[0033] the caprock depth-displacement pressure correlation formula is obtained;

[0034] the displacement pressure threshold value calculation formula is substituted into the caprock depth-displacement pressure correlation formula;

[0035] the caprock thickness threshold value calculation formula is obtained.

[0036] Preferably, the judging whether the overlying shale caprock of the oil and gas reservoir drilling target is an invalid caprock according to the position data of the oil and gas reservoir drilling target and the seismic response characteristics of the sandstone layer and the shale layer in the target region and the threshold thickness and the actual thickness of the overlying shale caprock of the oil and gas reservoir drilling target comprises the steps of:

[0037] the seismic response characteristics of the sandstone layer and the shale layer in the target region are obtained;

[0038] the position data of the oil and gas reservoir drilling target are obtained;

[0039] the coordinates and the depth of the oil and gas reservoir drilling target are obtained;

[0040] the three-dimensional seismic depth domain data body of the target region is obtained;

[0041] acquiring seismic response characteristics of the sandstone layer and the shale layer;

[0042] introducing the depth and the thickness into the three-dimensional seismic depth domain data volume;

[0043] acquiring the actual thickness according to the output of the three-dimensional seismic depth domain data volume and the seismic response characteristics;

[0044] acquiring a caprock thickness threshold calculation formula;

[0045] inputting the actual thickness into the caprock thickness threshold calculation formula and obtaining the threshold thickness;

[0046] determining whether the actual thickness is greater than or equal to the threshold thickness;

[0047] if yes, determining that the overlying shale caprock of the oil and gas reservoir drilling target is an effective caprock;

[0048] if no, determining that the overlying shale caprock of the oil and gas reservoir drilling target is an ineffective caprock.

[0049] Preferably, the acquiring of the seismic response characteristics of the sandstone layer and the shale layer in the target area comprises the steps of:

[0050] acquiring a three-dimensional seismic data volume of the target area;

[0051] performing horizon interpretation on the three-dimensional seismic data volume;

[0052] well-seismic calibration of the drilled well formations in the target area;

[0053] establishing a relationship between three-dimensional seismic wave data and three-dimensional geological body depth according to the calibration result;

[0054] acquiring a three-dimensional seismic depth domain data volume of the target area according to the relationship;

[0055] acquiring the depth and the thickness of the overlying shale caprock of the drilled well;

[0056] introducing the depth and the thickness into the three-dimensional seismic depth domain data volume;

[0057] the three-dimensional seismic depth domain data volume outputs the seismic response characteristics of the sandstone layer and the shale layer.

[0058] Preferably, the obtaining of the position data of the oil and gas reservoir drilling target comprises the steps of:

[0059] acquiring basic data of drilled wells in the target area;

[0060] acquiring a three-dimensional seismic depth domain data volume of the target area;

[0061] An acquisition oil and gas drilling target comprehensive optimization evaluation method is provided.

[0062] The coordinate and depth of the oil and gas reservoir drilling target are determined according to the oil and gas drilling target comprehensive optimization evaluation method, the basic data and the three-dimensional seismic depth domain data body.

[0063] The one or more technical solutions in the embodiments of the present application have at least the following technical effects or advantages: the method for predicting the effectiveness of the overlying argillaceous cap rock of the oil and gas reservoir drilling target provided by the present application takes the measured displacement pressure of the argillaceous cap rock as the starting point, obtains quantitative threshold thickness data of the argillaceous cap rock through regression and fitting according to the mutual correlation between the burial depth, thickness and sealing property of the cap rock, and then accurately predicts the effectiveness of the overlying argillaceous cap rock of the oil and gas reservoir drilling target, which can provide a basis for oil and gas reservoir drilling. BRIEF DESCRIPTION OF DRAWINGS

[0064] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced as follows. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without any creative effort.

[0065] Figure 1 is a flowchart of the method for predicting the effectiveness of the overlying argillaceous cap rock of the oil and gas reservoir drilling target provided by the embodiments of the present application. DETAILED DESCRIPTION

[0066] The advantages and various effects of the present application will be more clearly presented by the following specific embodiments and examples. Those skilled in the art should understand that these specific embodiments and examples are used to illustrate the present application, rather than limit the present application.

[0067] Throughout the specification, unless otherwise specifically indicated, the terms used herein are to be understood as having the meanings commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meanings as generally understood by those skilled in the art to which the present application belongs. If there is a conflict, the present specification takes precedence.

[0068] Unless otherwise specifically indicated, the various raw materials, reagents, instruments and equipment used in the present application can be purchased from the market or can be prepared by existing methods.

[0069] As Figure 1 In the embodiments of the present application, the present application provides a method for predicting the effectiveness of the overlying argillaceous cap rock of the oil and gas reservoir drilling target, which comprises the following steps:

[0070] S1: obtaining the depth and thickness of the overlying shale cap rock of the drilled well according to the basic data of the drilled well in the target area;

[0071] In the embodiment of the present application, the basic data of the drilled well in the target area in step S1 includes the following steps:

[0072] obtaining the mud logging data of the drilled well;

[0073] obtaining the core data of the drilled well;

[0074] obtaining the logging curve data of the drilled well;

[0075] obtaining the oil testing data of the drilled well.

[0076] In the embodiment of the present application, the method for obtaining the mud logging data of the drilled well is as follows: in the drilling process (i.e. the process of drilling the formation by the drill bit and grinding the rock), the rock debris of the underground formation encountered by the drill bit is brought to the wellhead by using the drilling fluid circulation system, and then the mud logging data is obtained by referring to the Oil and Gas Well Mud Logging Series Standard of the People's Republic of China Petroleum and Natural Gas Industry Standard SYT6831-2011.

[0077] In the embodiment of the present application, the method for obtaining the core data of the drilled well is as follows: in the drilling process (i.e. the process of drilling the formation by the drill bit and grinding the rock), a cylindrical rock sample is taken out from the hole using a ring-shaped core bit when approaching the target layer, and this sample is the core sample.

[0078] In the embodiment of the present application, the method for obtaining the logging curve data of the drilled well is as follows: by using the physical principles of electricity, magnetism, sound, etc., various logging instruments are lowered into the well by using the logging cable, and the ground testing instrument continuously records various changing parameters along the wellbore with depth, so as to obtain the logging curve data.

[0079] In the embodiment of the present application, the method for obtaining the oil testing data of the drilled well is as follows: the underground perforation is performed on the target layer, and then the oil, gas and water production is tested, and the bottom hole pressure and the oil, gas and water physical properties are obtained, and the oil layer, gas layer and water layer are directly determined according to the data.

[0080] In the embodiment of the present application, the advantage of obtaining the basic data of the drilled well in the target area is that the existing production data of the oilfield can be fully utilized, and it is not necessary to measure these data from zero, so as to reduce the cost of obtaining the original data as much as possible while realizing the prediction effect of the present application

[0081] In the embodiment of the present application, the step of obtaining the depth and thickness of the overlying shale cap rock of the drilled well according to the basic data of the drilled well in the target area in step S1 includes the following steps:

[0082] obtaining logging data, core data, well logging curve data and oil testing data in the basic data of the drilled well;

[0083] drawing a wellbore column chart and a lithology chart of the drilled well according to the logging data, the core data and the well logging curve data;

[0084] determining the oil and gas layer of the drilled well according to the oil testing data;

[0085] positioning the oil and gas layer in the wellbore chart;

[0086] obtaining the depth and thickness of the oil and gas layer from the wellbore chart;

[0087] obtaining the depth and thickness of the overlying shale cap rock of the drilled well from the wellbore chart.

[0088] In the embodiment of the present application, the wellbore column chart is drawn and the lithology chart is generated according to the logging data, the core data and the well logging curve data, and then the oil and gas layer in the target area is determined according to the oil testing data; then the oil and gas layer is positioned in the wellbore column chart, and the depth and thickness of the oil and gas layer and the depth and thickness of the overlying shale cap rock are directly obtained from the wellbore column chart.

[0089] In the embodiment of the present application, the advantage of obtaining the depth and thickness of the overlying shale cap rock of the drilled well according to the basic data of the drilled well in the target area is that the next step of fitting relationship of depth and thickness can be prepared, and the oil and gas layer of the drilled well can be determined according to the well number and depth of the oil testing data. The basic principle of the wellbore column chart is to provide a vertical depth display and display the data such as the depth, thickness and lithology of the oil and gas layer along the depth, so that the depth and thickness of the oil and gas layer and the depth and thickness of the overlying shale cap rock can be directly obtained from the wellbore column chart.

[0090] S2: sampling the core of the overlying shale cap rock and obtaining the displacement pressure test value;

[0091] In the embodiment of the present application, the step of sampling the core of the overlying shale cap rock and obtaining the displacement pressure test value in step S2 comprises the steps of:

[0092] obtaining the positions of all the oil and gas layers in the drilled well;

[0093] obtaining the depths of the overlying shale cap rocks of all the oil and gas layers;

[0094] sampling the cores of the overlying shale cap rocks corresponding to all the oil and gas layers according to the depths;

[0095] performing displacement pressure test on all the cores and obtaining the displacement pressure test values.

[0096] In the embodiment of the present application, the core is sampled according to the depth of the overlying argillaceous cap rock of the oil and gas reservoir obtained in step S1, and then the core is subjected to displacement pressure test. Specifically, the test steps of the displacement pressure test refer to the “People's Republic of China Petroleum and Natural Gas Industry Standard SY / T 5748-2013 Method for Determining Rock Gas Breakthrough Pressure”, which will not be described herein again. In addition, in order to enhance the representativeness of the results of the displacement pressure test of the core and improve the regression effect of the displacement pressure below, as many cores as possible need to be selected for testing, that is, the depth and thickness of the core sample should cover the range of all oil and gas reservoirs as much as possible.

[0097] In the embodiment of the present application, the core of the overlying argillaceous cap rock is sampled and the displacement pressure test value is obtained. The advantage is that the displacement pressure of the laboratory test is more accurate and can represent the sealing performance of the argillaceous cap rock.

[0098] S3: obtaining a displacement pressure threshold value calculation formula according to the thickness and the displacement pressure test value;

[0099] In the embodiment of the present application, step S4 of obtaining a displacement pressure threshold value calculation formula according to the thickness and the displacement pressure test value includes the steps of:

[0100] obtaining the thickness of all the overlying argillaceous cap rocks and the corresponding displacement pressure test values thereof;

[0101] preparing a first scatter plot of all the thicknesses and all the corresponding displacement pressure test values thereof;

[0102] envelope regression is performed on the first scatter plot;

[0103] obtaining the displacement pressure threshold value calculation formula.

[0104] As known, there are two basic factors for cap rock sealing, one is thickness, when the cap rock is thicker, the sealing ability is stronger; the other is sealing degree (displacement pressure), when the displacement pressure is higher, the sealing ability is stronger. These two factors can complement each other, when the thickness is large, the displacement pressure can be appropriately small, and it can also become an effective cap rock; when the displacement pressure is large, the thickness can be small, and it can also become an effective cap rock. According to this basic law, the displacement pressure threshold value regression of cap rocks of different thicknesses can be carried out according to the thickness and the displacement pressure test value.

[0105] In the embodiment of the present application, the caprock thickness obtained in step S2 and the displacement pressure test value are plotted into a scatter plot, and then envelope regression is performed on the scatter plot by using MATLAB software, so that an envelope line (i.e. a threshold line) of the caprock thickness and the displacement pressure test value is obtained, and an envelope regression formula is generated, which is the displacement pressure threshold value calculation formula for different thickness values.

[0106] In the embodiment of the present application, the expression of the displacement pressure threshold value calculation formula is:

[0107] H = 353 x P -1.414 ,

[0108] wherein H represents the caprock thickness, and the unit is m; P represents the displacement pressure, and the unit is MPa.

[0109] In the embodiment of the present application, the advantage of obtaining the displacement pressure threshold value calculation formula according to the thickness and the displacement pressure test value is that the common sense of the complementary relationship between the displacement pressure and the thickness is quantified.

[0110] S4: obtaining a caprock depth and caprock displacement pressure correlation formula according to the depth and the displacement pressure test value;

[0111] In the embodiment of the present application, obtaining the caprock depth and caprock displacement pressure correlation formula according to the depth and the displacement pressure test value in step S4 includes the steps of:

[0112] obtaining the depth of all the overlying shale caprocks and the corresponding displacement pressure test values thereof;

[0113] plotting a second scatter plot of all the thicknesses and all the corresponding displacement pressure test values thereof;

[0114] performing correlation regression on the second scatter plot;

[0115] obtaining the caprock depth and caprock displacement pressure correlation formula.

[0116] It is known that the sealing property of a shale caprock is not acquired at the time of deposition, but gradually increases with the burial depth after deposition and burial. Previous studies have shown that the shale caprocks in various regions have good correlation with displacement pressure, so the caprock depth and caprock displacement pressure correlation formula can be obtained according to the depth and the displacement pressure test value.

[0117] In the embodiment of the present application, the caprock depth obtained in step S2 and the displacement pressure test value are plotted into a scatter plot, and then correlation regression is performed by using the least square method in the excel software, and a caprock depth value and displacement pressure value correlation formula is obtained.

[0118] In the embodiment of the present application, the expression of the formula of the correlation between the cap layer depth and the cap layer displacement pressure is:

[0119] D = 1385.6 x P 0.47 ,

[0120] wherein D represents the cap layer depth, and the unit is m; and P represents the displacement pressure, and the unit is MPa.

[0121] In the embodiment of the present application, the advantage of obtaining the formula of the correlation between the cap layer depth and the cap layer displacement pressure according to the depth and the displacement pressure test value is that the common sense of the complementary relationship between the cap layer depth and the cap layer displacement pressure is quantified.

[0122] S5: obtaining a cap layer thickness threshold value calculation formula according to the displacement pressure threshold value calculation formula and the formula of the correlation between the cap layer depth and the cap layer displacement pressure;

[0123] In the embodiment of the present application, obtaining the cap layer thickness threshold value calculation formula according to the displacement pressure threshold value calculation formula and the formula of the correlation between the cap layer depth and the cap layer displacement pressure in step S5 includes the following steps:

[0124] obtaining the displacement pressure threshold value calculation formula;

[0125] obtaining the formula of the correlation between the cap layer depth and the cap layer displacement pressure;

[0126] substituting the displacement pressure threshold value calculation formula into the formula of the correlation between the cap layer depth and the cap layer displacement pressure;

[0127] obtaining the cap layer thickness threshold value calculation formula.

[0128] In the embodiment of the present application, the displacement pressure threshold value calculation formula obtained in step S3 is substituted into the formula of the correlation between the cap layer depth and the cap layer displacement pressure in step S5, so that the cap layer thickness threshold value calculation formula is obtained.

[0129] In the embodiment of the present application, the basic principle of obtaining the cap layer thickness threshold value calculation formula according to the displacement pressure threshold value calculation formula and the formula of the correlation between the cap layer depth and the cap layer displacement pressure is that the two correlation formulas have a common parameter “displacement pressure”, which can be brought into calculation. The significance of formula conversion is that, by bringing in and converting the intermediate parameter “displacement pressure”, the cap layer sealing property can be directly predicted by using the thickness and the depth. Since the test of the displacement pressure is derived from the coring experiment of the drilled well, it can only be used for “post-drilling” evaluation, and cannot be used for “pre-drilling” evaluation. However, the thickness and the depth data can be obtained from the analysis of the three-dimensional seismic data, so that the “pre-drilling” evaluation can be realized.

[0130] S6: calculating a threshold thickness and an actual thickness of the shale cap rock overlying the oil and gas drilling target according to position data of the oil and gas drilling target and seismic response characteristics of sandstone layers and shale layers in the target area, and judging whether the shale cap rock overlying the oil and gas drilling target is an invalid cap rock.

[0131] obtaining seismic response characteristics of sandstone layers and shale layers in the target area;

[0132] obtaining position data of an oil and gas drilling target;

[0133] obtaining coordinates and depth of the oil and gas drilling target;

[0134] obtaining a three-dimensional seismic depth domain data body of the target area;

[0135] obtaining seismic response characteristics of the sandstone layers and the shale layers;

[0136] inputting the coordinates and the depth into the three-dimensional seismic depth domain data body;

[0137] obtaining the actual thickness according to output of the three-dimensional seismic depth domain data body and the seismic response characteristics;

[0138] obtaining a cap rock thickness threshold value calculation formula;

[0139] inputting the actual thickness into the cap rock thickness threshold value calculation formula and obtaining the threshold thickness;

[0140] judging whether the actual thickness is greater than or equal to the threshold thickness;

[0141] if yes, judging that the shale cap rock overlying the oil and gas drilling target is a valid cap rock;

[0142] if no, judging that the shale cap rock overlying the oil and gas drilling target is an invalid cap rock.

[0143] In the embodiments of the present application, the coordinates and depth of the oil and gas drilling target are obtained, and the three-dimensional seismic depth domain data body is obtained, then the depth of the shale cap rock overlying the oil and gas drilling target is obtained according to the obtained seismic response characteristics of the sandstone layers and the shale layers, the depth of the shale cap rock overlying the oil and gas drilling target is input into the cap rock thickness threshold value calculation formula in step S5, the cap rock thickness threshold value calculation formula can output the threshold thickness of the shale cap rock overlying the oil and gas drilling target at the depth, then whether the shale cap rock overlying the oil and gas drilling target is a valid cap rock is judged by judging whether the actual thickness is greater than or equal to the threshold thickness. If the actual thickness is greater than or equal to the threshold thickness, it is judged that the shale cap rock overlying the oil and gas drilling target is a valid cap rock; otherwise, it is judged that the shale cap rock overlying the oil and gas drilling target is an invalid cap rock.

[0144] In the embodiment of the present application, the advantage of calculating the threshold thickness and the actual thickness of the overlying shale cap rock of the drilling target of the oil and gas reservoir according to the position data and the seismic response characteristics of the shale cap rock is that the depth and thickness data of the shale cap rock of the drilling target can be obtained, so as to perform pre-drilling cap rock evaluation.

[0145] In the embodiment of the present application, the step S6 of obtaining the seismic response characteristics of the sandstone layer and the shale layer in the target area comprises the steps of:

[0146] obtaining a three-dimensional seismic data volume of the target area;

[0147] performing horizon interpretation on the three-dimensional seismic data volume;

[0148] performing well-seismic calibration on the drilled formation in the target area;

[0149] establishing a relationship between the three-dimensional seismic wave data and the depth of the three-dimensional geological body according to the calibration result;

[0150] obtaining a three-dimensional seismic depth domain data volume of the target area according to the relationship;

[0151] obtaining the depth and the thickness of the overlying shale cap rock of the drilled well;

[0152] introducing the depth and the thickness into the three-dimensional seismic depth domain data volume;

[0153] the three-dimensional seismic depth domain data volume outputs the seismic response characteristics of the sandstone layer and the shale layer.

[0154] In the embodiment of the present application, after collecting the three-dimensional seismic data volume in the field, the horizon interpretation is performed on the three-dimensional seismic data volume, and the well-seismic calibration is performed on the drilled formation, so that the relationship between the three-dimensional seismic wave data and the depth of the three-dimensional geological body can be established, and finally the three-dimensional seismic depth domain data volume is obtained. Then the depth and the thickness of the drilled shale cap rock obtained in the step S2 are introduced into the three-dimensional seismic depth domain data volume, and the output of the three-dimensional seismic depth domain data volume is the seismic response characteristics of the sandstone layer and the shale layer.

[0155] Specifically, the method for obtaining the three-dimensional seismic data volume of the target area further comprises: collecting data (i.e., three-dimensional seismic data) reflected by the underground stratum after field shooting by using a receiver, and then processing the three-dimensional seismic data by using ProMax software, so as to obtain a three-dimensional seismic data volume; then importing the three-dimensional seismic data volume into Landmark software, and determining a seismic wavelet by using a self-correlation statistical method; then importing the logging curve data in step S1 into the three-dimensional seismic data volume, and using the seismic wavelet to calibrate and interpret the horizon of the target stratum; and then calibrating the stratum of the drilled well to establish the relationship between the three-dimensional seismic wave data and the depth of the three-dimensional geological volume, so as to obtain a three-dimensional seismic depth domain data volume.

[0156] In the embodiment of the present application, the advantage of obtaining the seismic response characteristics of the sandstone layer and the argillaceous rock layer in the target area is that the depth and thickness data of the drilled target argillaceous rock cap layer can be obtained.

[0157] In the embodiment of the present application, the obtaining of the position data of the oil and gas reservoir drilling target in step S6 comprises the steps of:

[0158] Obtaining the basic data of the drilled well in the target area;

[0159] Obtaining a three-dimensional seismic depth domain data volume of the target area;

[0160] Obtaining an oil and gas drilling target comprehensive optimization evaluation method;

[0161] According to the oil and gas drilling target comprehensive optimization evaluation method, the basic data and the three-dimensional seismic depth domain data volume, the coordinates and depth of the oil and gas reservoir drilling target are determined.

[0162] In the embodiment of the present application, according to the obtained basic data of the drilled well in the target area in step S1, the obtained three-dimensional seismic depth domain data volume of the target area in step S6, and the oil and gas drilling target comprehensive optimization evaluation method in the public number CN106199754B, the coordinate position and depth of the oil and gas reservoir drilling target are obtained.

[0163] In the embodiment of the present application, the advantage of obtaining the position data of the oil and gas reservoir drilling target is to obtain the depth and thickness data of the drilled target argillaceous rock cap layer, so as to perform pre-drilling cap layer evaluation.

[0164] The method for predicting the effectiveness of the overlying argillaceous rock cap layer of the oil and gas reservoir drilling target provided in the present application takes the measured displacement pressure of the argillaceous rock cap layer as the starting point, obtains the quantitative threshold thickness data of the argillaceous rock cap layer according to the mutual correlation between the cap layer burial depth, thickness and sealing property, and by using the regression and fitting method, and then accurately predicts the effectiveness of the overlying argillaceous rock cap layer of the oil and gas reservoir drilling target, which can provide a basis for oil and gas reservoir drilling.

[0165] It has to be noted that, in the present document, relational terms are intended only to convey a possible relationship between elements or

[0166] In conclusion, the above description merely illustrates the preferred embodiments of the present application and is not intended to limit the scope of the present application. Any modification, equivalent replacement or improvement made without departing from the spirit and principle of the present application shall fall within the scope of the present application.

Claims

1. A method for predicting the effectiveness of overlying argillaceous caprock over a drilling target in an oil and gas reservoir, characterized in that, The method includes the following steps: The depth and thickness of the overlying argillaceous caprock of the drilled wells are obtained based on the baseline data of the drilled wells in the target area. Core samples were taken from the overlying argillaceous caprock, and displacement pressure test values ​​were obtained. The formula for calculating the displacement pressure threshold value is obtained based on the thickness and the displacement pressure test value. A formula relating caprock depth to caprock displacement pressure is obtained based on the depth and the displacement pressure test value. The formula for calculating the caprock thickness threshold is obtained based on the displacement pressure threshold calculation formula and the correlation formula between caprock depth and caprock displacement pressure, including: Obtain the formula for calculating the displacement pressure threshold; Obtain the correlation formula between the caprock depth and the caprock displacement pressure; Substitute the formula for calculating the displacement pressure threshold into the formula for the correlation between caprock depth and caprock displacement pressure; Obtain the formula for calculating the cap layer thickness threshold; Based on the location data of the oil and gas reservoir drilling target and the seismic response characteristics of the sandstone and argillaceous layers in the target area, the threshold thickness and actual thickness of the overlying argillaceous caprock of the oil and gas reservoir drilling target are calculated to determine whether the overlying argillaceous caprock of the oil and gas reservoir drilling target is an invalid caprock, including: Obtain the three-dimensional seismic data volume of the target area; Perform layer interpretation on the aforementioned three-dimensional seismic data volume; Well-seismic calibration of the drilled formations in the target area; Establish the relationship between 3D seismic wave data and 3D geological body depth based on the calibration results; Based on the aforementioned relationship, obtain the three-dimensional seismic depth domain data volume of the target area; Obtain the depth and thickness of the overlying argillaceous caprock of the drilled well; Import the depth and thickness into the three-dimensional seismic depth domain data volume; The three-dimensional seismic depth domain data volume outputs the seismic response characteristics of the sandstone and argillaceous rock layers; Obtain location data of oil and gas reservoir drilling targets; Obtain the coordinates and depth of the oil and gas reservoir drilling target; Obtain the three-dimensional seismic depth domain data volume of the target area; Obtain the seismic response characteristics of the sandstone and argillaceous rock layers; Import the coordinates and depth into the three-dimensional seismic depth domain data volume; The actual thickness is obtained based on the output of the three-dimensional seismic depth domain data volume and the seismic response characteristics; Obtain the formula for calculating the cap layer thickness threshold; Input the actual thickness into the cap layer thickness threshold value calculation formula to obtain the threshold thickness; Determine whether the actual thickness is greater than or equal to the threshold thickness; If so, the overlying mudstone caprock over the oil and gas reservoir drilling target is determined to be an effective caprock; If not, the overlying mudstone caprock over the oil and gas reservoir drilling target is determined to be an invalid caprock.

2. The method for predicting the effectiveness of overlying argillaceous caprock over a drilling target in an oil and gas reservoir according to claim 1, characterized in that, The basic data includes one or more of the well logging data, core data, well logging curve data, and well testing data from the drilled wells.

3. The method for predicting the effectiveness of overlying argillaceous caprock over a drilling target in an oil and gas reservoir according to claim 2, characterized in that, Obtaining the depth and thickness of the overlying argillaceous caprock of the drilled well includes determining the location of the oil and gas layer in the drilled well using the logging data, core data, well logging curve data, and oil testing data in the basic data, in order to obtain the depth and thickness of the oil and gas layer.

4. The method for predicting the effectiveness of overlying argillaceous caprock over a drilling target in an oil and gas reservoir according to claim 1, characterized in that, The steps of sampling the core of the overlying argillaceous caprock and obtaining the displacement pressure test value include: Obtain the location of all oil and gas layers in the drilled well; Obtain the depth of the overlying argillaceous caprock over all the oil and gas reservoirs; Core samples were taken from the overlying argillaceous caprock corresponding to all the oil and gas layers at the specified depth. Displacement pressure tests were performed on all the core samples, and the displacement pressure test values ​​were obtained.

5. The method for predicting the effectiveness of overlying argillaceous caprock over a drilling target in an oil and gas reservoir according to claim 1, characterized in that, The formula for calculating the displacement pressure threshold value based on the thickness and the displacement pressure test value includes the following steps: Obtain the thickness of all the overlying argillaceous caprock layers and their corresponding displacement pressure test values; Compile a first scatter plot of all the stated thicknesses and their corresponding displacement pressure test values; Perform envelope regression on the first scatter plot; Obtain the formula for calculating the displacement pressure threshold.

6. The method for predicting the effectiveness of overlying argillaceous caprock over a drilling target in an oil and gas reservoir according to claim 1, characterized in that, The step of obtaining the correlation formula between caprock depth and caprock displacement pressure based on the depth and the displacement pressure test value includes the following steps: Obtain the depth of all the overlying argillaceous caprock layers and their corresponding displacement pressure test values; Compile a second scatter plot of all the stated depths and their corresponding displacement stress test values; Perform correlation regression on the second scatter plot; Obtain the correlation formula between the caprock depth and the caprock displacement pressure.

7. The method for predicting the effectiveness of overlying argillaceous caprock over a drilling target in an oil and gas reservoir according to claim 1, characterized in that, The process of obtaining the location data of oil and gas reservoir drilling targets includes the following steps: Obtain basic data on drilled wells in the target area; Obtain the three-dimensional seismic depth domain data volume of the target area; A comprehensive evaluation method for obtaining oil and gas drilling targets; The coordinates and depth of the oil and gas reservoir drilling target are determined based on the comprehensive optimization and evaluation method for oil and gas drilling targets, the basic data, and the three-dimensional seismic depth domain data volume.

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