Pre-drilling productivity prediction method for metamorphic rock buried hill naked eye well completion

Abstract

The invention discloses a pre-drilling productivity prediction method for metamorphic rock buried hill naked eye well completion, and the method comprises the steps: calculating the predicted productivity of a weathering crust of a pre-drilled well, and obtaining the predicted productivity of the weathering crust of the pre-drilled well according to the development magnitude of the weathering crust of the pre-drilled well and a weathering crust productivity template; calculating the predicted capacity of the pre-drilling well crack section, and obtaining the predicted capacity of the pre-drilling well crack section based on the unit crack development comprehensive index capacity of the development area, the crack development comprehensive index of the pre-drilling well and the dominant crack development index of the pre-drilling well; and calculating the buried hill productivity of the pre-drilling well, and obtaining the buried hill productivity of the pre-drilling well based on the predicted productivity of the drilling well weathering crust and the predicted productivity of the pre-drilling well crack section. According to the method, the problems that the productivity of the production well is difficult to split longitudinally and effectively due to the fact that the naked eye section contains different reservoir types and commingled production, and productivity prediction based on a geological model is difficult to establish and carry out are solved, rapid productivity prediction under metamorphic rock buried hill naked eye completion is effectively achieved, and efficient development of buried hill gas reservoirs of the thousand billions of Bohai Sea is guaranteed.

Description

Technical Field

[0001] This invention relates to the field of pre-drilling prediction and evaluation technology in petroleum exploration and development, and in particular to a method for predicting production capacity before drilling in metamorphic buried hill bare-hole completion. Background Technology

[0002] In recent years, the Bohai metamorphic buried hill gas field with a capacity of hundreds of billions of cubic meters has been included in the development agenda. Due to the drastic changes in the heterogeneity of the effective reservoir space of the metamorphic buried hill, the production capacity of the buried hill development wells varies greatly, which restricts the efficient development of the buried hill gas reservoir and affects the drilling success rate of development wells.

[0003] At present, in the domestic and foreign petroleum industry, the main focus of the production capacity of development wells in buried hill oil and gas reservoirs is on interpreting and evaluating the effective reservoirs in buried hills using post-drilling logging data, while there is a lack of relevant technologies for pre-drilling prediction of production capacity of development wells in metamorphic buried hill oil and gas reservoirs.

[0004] Therefore, for the development of buried hill bare-hole completions, it is necessary to develop a production capacity prediction method for buried hill bare-hole completions in metamorphic rocks through technological innovation. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned technical problems and propose a method for predicting the pre-drilling productivity of bare-hole completion wells in metamorphic buried hills.

[0006] To achieve the above objectives, this application provides the following technical solution:

[0007] A method for predicting pre-drilling productivity in bare-hole completion of metamorphic rock buried hill wells includes the following steps:

[0008] The buried hill production capacity of the development well is divided into the fracture section production capacity and the weathered crust production capacity of the development well.

[0009] The predicted productivity of the weathered crust of the pre-drilled well is calculated. The development level of the weathered crust of the pre-drilled well is obtained based on the post-stack interlayer seismic amplitude. The weathered crust productivity template corresponding to the development level of the weathered crust is obtained through the weathered crust productivity of the development well. The predicted productivity of the weathered crust of the pre-drilled well is obtained based on the development level of the weathered crust of the pre-drilled well and the weathered crust productivity template.

[0010] The predicted productivity of the pre-drilled well fractured section is calculated. Based on the comprehensive fracture development index of the development well and the productivity of the fractured section of the development well, the productivity per unit fracture development index of the development area is obtained. Based on the coherence extracted from the post-stack seismic data, the comprehensive fracture development index of the pre-drilled well is obtained. Based on the proportion of the comprehensive fracture development index of the pre-drilled well with a strength of 50% or more, the dominant fracture development index of the pre-drilled well is obtained. Based on the productivity per unit fracture development index of the development area, the comprehensive fracture development index of the pre-drilled well, and the dominant fracture development index of the pre-drilled well, the predicted productivity of the pre-drilled well fractured section is obtained.

[0011] The pre-drilled buried hill capacity is calculated based on the predicted capacity of the weathered crust of the well and the predicted capacity of the fractured section of the pre-drilled well.

[0012] Optionally, the formula for calculating the magnitude of weathering crust development in pre-drilled wells is:

[0013] CR y =10*|(Am y -Am max ) / (Am max -Am min )| (1)

[0014] Among them, CR y The quantity of weathering crust development in the pre-drilled well is on the order of magnitude, dimensionless; Am y Am represents the seismic amplitude of the weathered crust in the pre-drilled well, dimensionless. max Am represents the maximum seismic amplitude of the weathering crust in the study area, dimensionless. min The minimum seismic amplitude of the weathering crust in the study area is dimensionless.

[0015] Optionally, the formula for calculating the comprehensive index of fracture development in pre-drilled wells is as follows:

[0016]

[0017] Where y is the coherent property volume after mirror transformation, dimensionless; x is the coherent property volume, dimensionless; TFR is the fracture development index, dimensionless; top is the depth sounding at the top of the buried hill, m; TD is the depth sounding at the bottom of the well, m; y i C0 is the attribute value of the coherence curve at a certain depth point on the well trajectory, dimensionless; C0 is the background value of the coherence curve, dimensionless; Δh is the difference in measured depth between two adjacent sampling points of the curve, in meters.

[0018] Optionally, the formula for calculating the unit crack development comprehensive index productivity of the development zone is as follows:

[0019]

[0020] Among them, Q LTFR The unit crack development comprehensive index productivity, m 3 / d;Q i For the fractured section productivity of the i-th well in the development zone, m 3 / d; n is the total number of wells involved in the calculation; TFR i denoted as the comprehensive index of fracture development in the i-th well, dimensionless.

[0021] Optionally, the formula for calculating the dominant fracture development factor in pre-drilled wells is as follows:

[0022]

[0023] Among them, y i The curve represents the dominant crack development curve, dimensionless; x i 1 is the normalized coherence curve, dimensionless; F is the dominant fracture development factor, dimensionless; TFR is the comprehensive fracture development index, dimensionless; top is the depth at the top of the buried hill, m; TD is the depth at the bottom of the well, m; Δh is the difference in measurement depth between two adjacent sampling points of the curve, m.

[0024] Optionally, the formula for calculating the production capacity of pre-drilled buried hills is:

[0025]

[0026] Among them, Q TFR For the predicted productivity of the pre-drilled fractured section, m 3 / d; TFR is the pre-drilled fracture development index, dimensionless; Q LTFR The unit crack development comprehensive index production capacity of the development zone, m 3 / d; F is the dominant fracture development factor, dimensionless; b is the dominant fracture productivity correction factor, dimensionless, with a default value of 1; Q y To increase the production capacity of pre-drilled buried hills, m 3 / d;Q CRy For the pre-drilled well, the amount of weathering crust development is on the order of m 3 / d.

[0027] In summary, the technical effects and advantages of this invention are as follows: The method of this invention solves the problem that it is difficult to effectively divide the production capacity of production wells vertically when the bare section contains different reservoir types and the production is combined with other production, and it is difficult to establish and carry out production capacity prediction based on geological models. It effectively realizes rapid production capacity prediction after bare section completion in metamorphic buried hills, and safeguards the efficient development of the hundreds of billions of cubic meters of buried hill gas reservoirs in the Bohai Sea. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a flowchart illustrating a method for predicting pre-drilling productivity in a metamorphic rock buried hill bare-hole well completion according to an embodiment of the present invention.

[0030] Figure 2 This is a weathering crust development index diagram of a buried hill in a well area according to one embodiment of the present invention;

[0031] Figure 3This is a plan view of the properties of the fractured section of a buried hill in a well area according to one embodiment of the present invention;

[0032] Figure 4 This is a cross-section of the pre-drilled X5 fracture development in one embodiment of the present invention. Detailed Implementation

[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0035] This embodiment provides a pre-drilling productivity prediction method for bare-hole completion of metamorphic buried hill wells, mainly utilizing drilled (development wells) and post-stack seismic data to predict pre-drilling oil and gas productivity. The implementation process is as follows: First, based on the effective reservoir characteristics of the buried hill section, it is vertically classified into weathered crust and fractured sections, and the buried hill productivity is divided into weathered crust and fractured sections based on the weathered crust development level; then, the relative development degree of the weathered crust is quantitatively characterized using the post-stack inter-layer seismic amplitude and transformation, and a productivity template corresponding to the weathered crust development level is obtained through wellpoint productivity distribution calibration, and the weathered crust productivity of the pre-drilled well is obtained based on the weathered crust development degree of the pre-drilled well and the weathered crust productivity template; secondly, coherent volumes are extracted using post-stack seismic bodies and normalized and mirrored in the paleoburied hill section, and the data along the well trajectory is extracted. The coherence curve is obtained; next, the comprehensive index of fracture development in the pre-drilled well in the buried hill section is calculated using an integral formula, and the comprehensive index of fracture development in the drilled well (development well) and the productivity of the fractured section are combined. The productivity value corresponding to the comprehensive index of fracture development per unit of buried hill is obtained by integral summation; next, the dominant fracture development factor is obtained by using the proportion of the comprehensive index of fracture development with intensity above 50%; finally, the productivity of the fractured section of the pre-drilled well is obtained by multiplying the comprehensive index of fracture development in the pre-drilled well by the productivity per unit of the comprehensive index of fracture development, the dominant fracture development factor and the correction coefficient, and the productivity of the weathered crust section and the productivity of the fractured section are added together to obtain the total productivity of the pre-drilled well.

[0036] like Figure 1 As shown, the specific steps include:

[0037] (1) Data Foundation

[0038] The data should include post-stack seismic data and data from drilled production wells, mainly including: ① seismic data in the depth domain and seismic horizons at the top of the buried hill; ② data from drilled wells (development wells), including well trajectories, stratification depths at the top of the buried hill, and production capacity of development wells in the buried hill.

[0039] (2) Weathering crust development magnitude and energy splitting

[0040] The RMS amplitudes of the back-stack buried hilltop and 75m below it were extracted, and after maximum-minimum reversal and normalization, multiplied by 10 to obtain a quantitative characterization value for the relative development level (0-10) of the weathering crust. Based on the weathering crust productivity of the development well, the productivity template corresponding to the weathering crust development level was obtained through well point calibration, as shown in Table 1. The weathering crust productivity Q of the pre-drilled well was obtained by using the productivity template corresponding to the weathering crust development level of the pre-drilled well (Table 1). CRy The formula for calculating the magnitude of weathering crust development in pre-drilled wells is:

[0041] CR y =10*|(Am y -Am max ) / (Am max -Am min )| (1)

[0042] Among them, CR y The quantity of weathering crust development in pre-drilled wells is on the order of dimensionless; Am y Am represents the seismic amplitude of the weathered crust in the pre-drilled well, dimensionless. max Am represents the maximum seismic amplitude of the weathering crust in the study area, dimensionless. min Q represents the minimum seismic amplitude of the weathering crust in the study area, which is dimensionless; CRy For the predicted production capacity of the weathered crust of the pre-drilled well, m 3 / d.

[0043] Table 1. Weathering crust development magnitude and production capacity template

[0044]

[0045] (3) Comprehensive index of fracture development in pre-drilled wells

[0046] Coherence volumes were extracted using post-stack seismic data and normalized and mirrored in the buried hill section. The mirrored transformation showed a positive correlation between the transformed properties and the degree of fracture development. Coherence curves along the well trajectory were extracted, and the comprehensive fracture development index of the buried hill section was calculated using an integral formula (see Table 2). Figure 3 :

[0047]

[0048] Where y is the coherent property volume after mirror transformation, dimensionless; x is the coherent property volume, dimensionless; TFR is the fracture development index, dimensionless; top is the depth sounding at the top of the buried hill, m; TD is the depth sounding at the bottom of the well, m; y i C0 is the attribute value of the coherence curve at a certain depth point on the well trajectory, dimensionless; C0 is the background value of the coherence curve, dimensionless; Δh is the difference in measured depth between two adjacent sampling points of the curve, in meters.

[0049] (4) Calculate the production capacity corresponding to the unit crack development comprehensive index of the development zone.

[0050] By combining the comprehensive fracture development index of drilled (development wells) and the productivity of fractured sections, the productivity per unit fracture development index of the development area is obtained using the following formula:

[0051]

[0052] Among them, Q LTFR The unit crack development comprehensive index productivity, m 3 / d;Q i For the fractured section productivity of the i-th well in the development zone, m 3 / d; n is the total number of wells involved in the calculation; TFR i denoted as the comprehensive index of fracture development in the i-th well, dimensionless.

[0053] (5) Determine the dominant crack development factor

[0054] The dominant fracture development is determined by the proportion of fracture development in pre-drilled wells with a strength of 50% or higher.

[0055] Factors, see Table 2:

[0056]

[0057] Among them, y i The curve represents the dominant crack development curve, dimensionless; x i 1 is the normalized coherence curve, dimensionless; F is the dominant fracture development factor, dimensionless; TFR is the comprehensive fracture development index, dimensionless; top is the depth at the top of the buried hill, m; TD is the depth at the bottom of the well, m; Δh is the difference in measurement depth between two adjacent sampling points of the curve, m.

[0058] (6) Determine the pre-drilled well buried hill capacity (total pre-drilled well capacity)

[0059] The fracture section productivity is obtained by multiplying the pre-drilled well's TFR by the productivity scale formed by the drilled fracture section. The pre-drilled well's weathered crust productivity is then added to the predicted productivity of the fracture section to obtain the pre-drilled well's buried hill productivity, as shown in Table 2.

[0060]

[0061] Among them, Q TFR For the predicted productivity of the pre-drilled fractured section, m 3 / d; TFR is the pre-drilled fracture development index, dimensionless; Q LTFR The unit crack development comprehensive index productivity, m 3 / d; F is the dominant fracture development factor, dimensionless; b is the dominant fracture productivity correction factor, dimensionless, with a default value of 1; Q y To increase the production capacity of pre-drilled buried hills, m 3 / d;Q CRy For predicting the production capacity of the weathered crust in pre-drilled wells, m 3 / d.

[0062] Table 2 Calculation Table of Relevant Parameters

[0063]

[0064]

[0065] As can be seen from Table 2, low-yield and inefficient wells are generally classified as low-productivity wells. The overall prediction accuracy rate for productive wells is approximately 85%, with production exceeding 350 cubic meters per day. For example, pre-drilled well X14, after well trajectory optimization, traversed multiple well-developed fracture zones (see attached table). Figure 4 The above method for predicting the production capacity of metamorphic buried hill development wells before drilling has been effectively verified.

[0066] This method solves the problem that the production capacity of production wells is difficult to effectively divide vertically due to the presence of different reservoir types in the bare-hole section and the combined production, making it difficult to establish and conduct production capacity prediction based on geological models. It effectively realizes rapid production capacity prediction after completion of bare-hole metamorphic buried hill wells.

[0067] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the systems disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple; relevant parts can be referred to the method section.

[0068] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for predicting pre-drilling productivity in bare-hole completion of metamorphic buried hill wells, characterized in that, Includes the following steps: The buried hill production capacity of the development well is divided into the fracture section production capacity and the weathered crust production capacity of the development well. The predicted productivity of the weathered crust of the pre-drilled well is calculated. The development level of the weathered crust of the pre-drilled well is obtained based on the post-stack interlayer seismic amplitude. The weathered crust productivity template corresponding to the development level of the weathered crust is obtained through the weathered crust productivity of the development well. The predicted productivity of the weathered crust of the pre-drilled well is obtained based on the development level of the weathered crust of the pre-drilled well and the weathered crust productivity template. The predicted productivity of the pre-drilled well fractured section is calculated. Based on the comprehensive fracture development index of the development well and the productivity of the fractured section of the development well, the productivity per unit fracture development index of the development area is obtained. Based on the coherence extracted from the post-stack seismic data, the comprehensive fracture development index of the pre-drilled well is obtained. Based on the proportion of the comprehensive fracture development index of the pre-drilled well with a strength of 50% or more, the dominant fracture development index of the pre-drilled well is obtained. Based on the productivity per unit fracture development index of the development area, the comprehensive fracture development index of the pre-drilled well, and the dominant fracture development index of the pre-drilled well, the predicted productivity of the pre-drilled well fractured section is obtained. The pre-drilled buried hill capacity is calculated based on the predicted capacity of the weathered crust of the well and the predicted capacity of the fractured section of the pre-drilled well.

2. The method for predicting pre-drilling productivity in bare-hole completion of metamorphic buried hill wells according to claim 1, characterized in that, The formula for calculating the magnitude of weathering crust development in pre-drilled wells is: CR y =10*|(Am y -Am max ) / (Am max -Am min )| (1) Among them, CR y The quantity of weathering crust development in the pre-drilled well is on the order of magnitude, dimensionless; Am y Am represents the seismic amplitude of the weathered crust in the pre-drilled well, dimensionless. max Am represents the maximum seismic amplitude of the weathering crust in the study area, dimensionless. min The minimum seismic amplitude of the weathering crust in the study area is dimensionless.

3. The method for predicting pre-drilling productivity in bare-hole completion of metamorphic buried hill wells according to claim 1, characterized in that, The formula for calculating the comprehensive index of fracture development in pre-drilled wells is as follows: Where y is the coherent property volume after mirror transformation, dimensionless; x is the coherent property volume, dimensionless; TFR is the fracture development index, dimensionless; top is the depth sounding at the top of the buried hill, m; TD is the depth sounding at the bottom of the well, m; y i C0 is the attribute value of the coherence curve at a certain depth point on the well trajectory, dimensionless; C0 is the background value of the coherence curve, dimensionless; Δh is the difference in measured depth between two adjacent sampling points of the curve, in meters.

4. The method for predicting pre-drilling productivity in bare-hole completion of metamorphic buried hill wells according to claim 1, characterized in that, The formula for calculating the unit crack development comprehensive index productivity of the development zone is as follows: Among them, Q LTFR The comprehensive index of crack development capacity is expressed in m. 3 / d;Q i For the fractured section productivity of the i-th well in the development zone, m 3 / d; n is the total number of wells involved in the calculation; TFR i denoted as the comprehensive index of fracture development in the i-th well, dimensionless.

5. The method for predicting pre-drilling productivity in bare-hole completion of metamorphic buried hill wells according to claim 1, characterized in that, The formula for calculating the dominant fracture development factor in pre-drilled wells is as follows: Among them, y i The curve represents the dominant crack development curve, dimensionless; x i 1 is the normalized coherence curve, dimensionless; F is the dominant fracture development factor, dimensionless; TFR is the comprehensive fracture development index, dimensionless; top is the depth at the top of the buried hill, m; TD is the depth at the bottom of the well, m; Δh is the difference in measurement depth between two adjacent sampling points of the curve, m.

6. The method for predicting pre-drilling productivity in bare-hole completion of metamorphic buried hill wells according to claim 1, characterized in that, The formula for calculating the production capacity of pre-drilled buried hills is: Among them, Q TFR For the predicted productivity of the pre-drilled fractured section, m 3 / d; TFR is the pre-drilled fracture development index, dimensionless; Q LTFR The unit crack development comprehensive index production capacity of the development zone, m 3 / d; F is the dominant fracture development factor, dimensionless; b is the dominant fracture productivity correction factor, dimensionless, with a default value of 1; Q y To increase the production capacity of pre-drilled buried hills, m 3 / d;Q CRy For the pre-drilled well, the amount of weathering crust development is on the order of m 3 / d.

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