Disclosure of Invention
The invention provides a method for calculating a heterogeneous stress field of a deep shale complex formation, aiming at solving the problems that the stress field of the deep shale complex formation in the prior art changes rapidly in a small area and a rapid and accurate calculation method of the heterogeneous stress field is lacked.
The technical scheme provided by the invention for solving the technical problems is as follows: a method for calculating the inhomogeneous stress field of deep shale complex stratum includes
Determining a stratum triaxial stress gradient under local coordinates of each well position according to stratum stress data and well position coordinate data of drilled wells in a target area;
determining a stratum stress tensor under the central local coordinate of the reservoir at each well position according to the stratum triaxial stress gradient under the local coordinate of each well position and the vertical depth data of the central part of the reservoir in the target area;
determining the formation stress tensor under the central global coordinate of the reservoir at each well position according to the formation stress tensor under the central local coordinate of the reservoir at each well position and a tensor coordinate system conversion algorithm;
determining a stratum stress tensor under the central global coordinate of the reservoir at any position in a target area and a stratum stress tensor component distribution cloud picture under the central global coordinate in the target area according to the stratum stress tensor under the central global coordinate of the reservoir at each well position and a natural adjacent point three-dimensional interpolation method;
determining a stratum triaxial main stress value and a direction component thereof under the middle local coordinate of the reservoir at any position in the target area according to the stratum stress tensor under the middle global coordinate of the reservoir at any position in the target area;
according to stratum triaxial main stress values and direction components of the stratum triaxial main stress values under the middle part local coordinates of the reservoir at any position in the target region, drawing a stratum maximum horizontal main stress value, a stratum minimum horizontal main stress value, a stratum vertical main stress value distribution cloud chart and maximum and minimum horizontal stress direction vector charts under the local coordinates in the target region;
and determining the non-uniform distribution condition of the triaxial stress field of the stratum at any position in the target region according to the distribution cloud graph of the maximum horizontal main stress value, the minimum horizontal main stress value and the vertical main stress value of the stratum under the local coordinate in the target region and the direction vector graphs of the maximum horizontal stress and the minimum horizontal stress.
The further technical scheme is that the method for determining the triaxial stress gradient of the stratum under the local coordinate of each well position according to the stratum stress data and the well position coordinate data of the drilled well in the target area comprises the following steps:
collecting stratum stress data obtained by measuring drilled wells in a target area, wherein the stratum stress data comprises a maximum horizontal main stress value, a minimum horizontal main stress value and a vertical main stress value;
collecting coordinate data of drilled well positions in a target area and the vertical depth of each well stratum stress measuring point, and drawing a well position distribution diagram;
respectively calculating three-axis stress gradients of the stratum under the local coordinates of each well position by using the following formula, wherein the three-axis stress gradients of the stratum comprise a maximum horizontal main stress gradient, a minimum horizontal main stress gradient and a vertical main stress gradient;
in the formula: gi H、Gi h、Gi vThe maximum horizontal main stress gradient, the minimum horizontal main stress gradient and the vertical main stress gradient of the stratum at the No. i well position are Pa/m; sigmaiH、σi h、σi vThe maximum horizontal main stress value, the minimum horizontal main stress value and the vertical main stress value of the stratum at the I-type well position are Pa; diMeasuring the vertical depth m of a formation stress data measuring point of a No. i well; and i is the number of the formation stress value measuring well.
The further technical scheme is that the step of determining the stratum stress tensor of each well position under the central local coordinate of the reservoir according to the triaxial stress gradient of the reservoir under the local coordinate of each well position and the vertical depth data of the central part of the reservoir in the target area comprises the following steps:
collecting vertical depth data of the middle part of a reservoir in a target area;
respectively calculating the stratum triaxial stress values under the middle local coordinates of the reservoir at each well position by using the following formula;
in the formula: gi H、Gi h、Gi vThe maximum horizontal main stress gradient, the minimum horizontal main stress gradient and the vertical main stress gradient of the stratum at the No. i well position are Pa/m; sigmai Hmid、σi hmid、σi vmidThe maximum horizontal main stress value, the minimum horizontal main stress value and the vertical main stress value of the stratum under the middle local coordinate of the reservoir at the position of the No. i well are Pa; dmidThe vertical depth m of the middle part of the reservoir in the target area;
assembling stratum triaxial stress values under the central local coordinates of the reservoir at each well position into a tensor form by using the following formula;
in the formula: sigmai Hmid、σi hmid、σi vmidThe maximum horizontal main stress value, the minimum horizontal main stress value and the vertical main stress value of the stratum under the middle local coordinate of the reservoir at the position of the No. i well are Pa; sigmai mid|localIs the stratum stress tensor Pa under the central local coordinate of the reservoir at the position of the No. i well.
The further technical scheme is that the step of determining the formation stress tensor under the central global coordinate of the reservoir at each well position according to the formation stress tensor under the central local coordinate of the reservoir at each well position and a tensor coordinate system conversion algorithm comprises the following steps:
collecting the maximum horizontal main stress direction of each well position obtained by the measurement of the drilled well in the target area, and calculating the included angle between the maximum horizontal main stress direction and the x axis of the global coordinate system;
respectively calculating stratum stress tensor components under the central global coordinates of the reservoir at each well position by using a tensor coordinate system conversion algorithm according to the following formula;
in the formula: sigmai xx、σi yy、σi xy、σi xz、σi yz、σi zzThe method comprises the following steps of (1) forming a formation stress tensor component Pa under the central global coordinate of a reservoir at the position of a well I; thetaiThe included angle between the maximum horizontal main stress of the No. i well and the x axis of the global coordinate system is degree; sigmai Hmid、σi hmid、σi vmidThe maximum horizontal main stress value, the minimum horizontal main stress value and the vertical main stress value of the stratum under the middle local coordinate of the reservoir at the position of the No. i well are Pa;
assembling stratum stress tensor components under the central global coordinate of the reservoir at each well position into a tensor form by using the following formula;
in the formula: sigmai xx、σi yy、σi xy、σi xz、σi yz、σi zzThe method comprises the following steps of (1) forming a formation stress tensor component Pa under the central global coordinate of a reservoir at the position of a well I; pa; sigmai mid|globalAnd the formation stress tensor is Pa under the central global coordinate of the reservoir at the position of the No. i well.
The further technical scheme is that the method for determining the stratum stress tensor of the reservoir at any position in the target area under the global coordinate in the middle of the reservoir at each well position and the component distribution cloud pictures of the stratum stress tensor under the global coordinate in the target area according to the stratum stress tensor under the global coordinate in the middle of the reservoir at each well position and the three-dimensional interpolation method of the natural adjacent points comprises the following steps:
according to the stratum stress tensor component under the central global coordinate of the reservoir at each well position, calculating the stratum stress tensor component under the central global coordinate of the reservoir at any position in the target area by a natural adjacent point three-dimensional interpolation method by using the following formula;
in the formula: sigmai mid|globalThe method comprises the steps of (1) forming a formation stress tensor Pa under the global coordinate of the middle part of a reservoir at any position in a target area; sigmaxx、σyy、σxy、σxz、σyz、σzzThe method comprises the following steps of (1) forming a formation stress tensor component Pa under the global coordinate of the middle part of a reservoir at any position in a target area; interp3N is a natural neighboring point three-dimensional interpolation operator;
assembling the formation stress tensor components under the central global coordinate of the reservoir at any position in the target area into a tensor form by using the following formula;
in the formula: sigmai mid|globalThe method comprises the steps of (1) forming a formation stress tensor Pa under the global coordinate of the middle part of a reservoir at any position in a target area; sigmaxx、σyy、σxy、σxz、σyz、σzzThe method comprises the following steps of (1) forming a formation stress tensor component Pa under the global coordinate of the middle part of a reservoir at any position in a target area;
and drawing a distribution cloud picture of the formation stress tensor components under the global coordinate in the target area.
The further technical scheme is that the stratum triaxial principal stress value under the central local coordinate of the reservoir at any position in the target area is determined according to the stratum stress tensor under the central global coordinate of the reservoir at any position in the target area, and the directional components of the stratum triaxial principal stress value comprise:
according to the stratum stress tensor under the central global coordinate of the reservoir at any position in the target area, calculating the stratum stress tensor eigenvalue and eigenvector matrix under the central local coordinate of the reservoir at any position in the target area by utilizing the following formula through the matrix eigenvalue and eigenvector operation;
[V,D]=eig(σmid|global)
in the formula: eig is a matrix eigenvalue and eigenvector operator; v is a stratum stress tensor eigenvalue matrix Pa under the middle local coordinate of the reservoir at any position in the target area; d is a formation stress tensor eigenvector matrix under the middle local coordinate of the reservoir at any position in the target area, and is dimensionless; sigmamid|globalThe method comprises the steps of (1) forming a formation stress tensor Pa under a global coordinate in the middle of a reservoir;
extracting the maximum horizontal main stress value, the minimum horizontal main stress value, the vertical main stress value and each main stress direction component of the stratum under the middle local coordinate of the reservoir at any position in the target area from the stratum stress tensor eigenvalue and eigenvector matrix under the middle local coordinate of the reservoir at any position in the target area by using the following formula;
V=[σhmid,σHmid,σvmid]
in the formula: v is the characteristic moment of formation stress tensor under the middle local coordinate of the reservoir at any position in the target areaArray, Pa; d is a formation stress tensor eigenvector matrix under the middle local coordinate of the reservoir at any position in the target area, and is dimensionless; sigmaHmid、σhmid、σvmidThe maximum horizontal main stress value, the minimum horizontal main stress value and the vertical main stress value Pa of the stratum under the middle local coordinate of the reservoir at any position in the target area are obtained; x is the number ofhmid、yhmid、zhmidThe minimum horizontal principal stress direction component of the stratum under the middle local coordinate of the reservoir at any position in the target area is dimensionless; x is the number ofHmid、yHmid、zHmidThe method is characterized in that the method is a formation maximum horizontal principal stress direction component under the middle local coordinate of a reservoir at any position in a target region and is dimensionless; x is the number ofvmid、yvmid、zvmidThe vertical principal stress direction component of the stratum under the middle local coordinate of the reservoir at any position in the target area is dimensionless.
The invention has the following beneficial effects: compared with the prior art, the method is specially used for solving the problem that the acquisition means of stress field data of the deep shale complex formation is insufficient, and a tensor coordinate system conversion algorithm and a natural adjacent point three-dimensional interpolation method are combined, so that a calculation method of the non-uniform stress field of the deep shale complex formation is provided; because the method can calculate the inhomogeneous distribution condition of the triaxial stress field of the stratum at any position in the target area only by depending on limited data such as the triaxial stress value, the maximum horizontal main stress direction and the like of the stratum drilled with the well in the target area without large-scale geological structure mechanical modeling, the method solves the problems that the stratum stress field of the complex structure of the deep shale changes faster in a smaller area and a fast and accurate inhomogeneous stratum stress field calculation method is lacked.
Detailed Description
The technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings, and it should be understood that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
As shown in FIG. 1, the method for calculating the inhomogeneous stress field of the deep shale complex formation stratum comprises the following steps:
step A, calculating a stratum triaxial stress gradient under local coordinates of each well position according to drilled well data in a target area;
step A, calculating a flow:
collecting formation stress data obtained by measuring drilled wells in a target area, wherein the formation stress data comprises a maximum horizontal main stress value, a minimum horizontal main stress value and a vertical main stress value;
collecting coordinate data of drilled well positions in the target area and the vertical depth of the stratum stress measuring points of each well, and drawing a well position distribution diagram;
thirdly, calculating three-axis principal stress gradients of the stratum at each well position respectively by using an equation (1), wherein the three-axis principal stress gradients of the stratum comprise a maximum horizontal principal stress gradient, a minimum horizontal principal stress gradient and a vertical principal stress gradient;
in the formula: gi H、Gi h、Gi vThe maximum horizontal main stress gradient, the minimum horizontal main stress gradient and the vertical main stress gradient of the stratum at the No. i well position are Pa/m; sigmai H、σi h、σi vThe maximum horizontal main stress value, the minimum horizontal main stress value and the vertical main stress value of the stratum at the I-type well position are Pa; diMeasuring the vertical depth m of a formation stress data measuring point of a No. i well; and i is the number of the formation stress value measuring well.
B, calculating the maximum horizontal principal stress value, the minimum horizontal principal stress value and the vertical principal stress value of the stratum under the local coordinate of the middle part of the reservoir at each well position based on the triaxial principal stress gradient of the stratum and the vertical depth data of the middle part of the reservoir in the target area in the step A, and assembling the maximum horizontal principal stress value, the minimum horizontal principal stress value and the vertical principal stress value into a stratum stress tensor form under the local coordinate;
step B, calculating a flow:
collecting vertical depth data of the middle part of a reservoir in a target area;
secondly, calculating the stratum triaxial stress value under the middle local coordinate of the reservoir at each well position by using an equation (2), wherein the equation comprises the following steps: the maximum horizontal main stress value, the minimum horizontal main stress value and the vertical main stress value of the stratum;
thirdly, assembling stratum triaxial stress values under the central local coordinate of the reservoir at the position of the well I into a tensor form by using an equation (3);
in the formula: sigmaiHmid、σi hmid、σi vmidThe maximum horizontal main stress value, the minimum horizontal main stress value and the vertical main stress value of the stratum under the middle local coordinate of the reservoir at the position of the No. i well are Pa; dmidThe vertical depth m of the middle part of the reservoir in the target area; sigmai mid|localThe method comprises the following steps of (1) forming a formation stress tensor Pa under a central local coordinate of a reservoir at a well position I;
step C, calculating a stratum stress tensor component under the central global coordinate of the reservoir at each well position through a tensor coordinate system conversion algorithm based on the stratum stress tensor under the central local coordinate of the reservoir at each well position obtained in the step B;
step C, calculating a flow:
collecting the maximum horizontal main stress direction of each well position obtained by drilling and setting well measurement in a target area, and calculating the included angle between the maximum horizontal main stress direction and the x axis of the global coordinate system;
respectively calculating the formation stress tensor components under the central global coordinate of the reservoir at each well position by using an equation (5) through a tensor coordinate system conversion algorithm;
thirdly, assembling the formation stress tensor components under the central global coordinate of the reservoir at each well position into a tensor form by using an equation (4);
in the formula: sigmai xx、σi yy、σi xy、σixz、σi yz、σi zzThe method comprises the following steps of (1) forming a formation stress tensor component Pa under the central global coordinate of a reservoir at the position of a well I; thetaiThe included angle between the maximum horizontal main stress of the No. i well and the x axis of the global coordinate system is degree;
step D, calculating the stratum stress tensor component under the central global coordinate of the reservoir at any position in the target area through a natural adjacent point three-dimensional interpolation method based on the stratum stress tensor under the central global coordinate of the reservoir at each well position obtained in the step C, assembling the stratum stress tensor component into a stratum stress tensor form under the global coordinate, and drawing a stratum stress tensor component distribution cloud picture under the global coordinate in the target area;
step D, calculating a flow:
calculating the stratum stress tensor component under the central global coordinate of the reservoir at any position in a target area by using an equation (7) through a natural adjacent point three-dimensional interpolation method according to the stratum stress tensor component under the central global coordinate of the reservoir at each well position;
assembling the formation stress tensor components under the global coordinate of the middle part of the reservoir at any position in the target area into a tensor form by using an equation (6);
thirdly, drawing a distribution cloud picture of stratum stress tensor components under the global coordinate in the target area;
in the formula: sigmai mid|globalThe method comprises the steps of (1) forming a formation stress tensor Pa under the global coordinate of the middle part of a reservoir at any position in a target area; sigmaxx、σyy、σxy、σxz、σyz、σzzThe method comprises the following steps of (1) forming a formation stress tensor component Pa under the global coordinate of the middle part of a reservoir at any position in a target area; interp3N is a natural neighboring point three-dimensional interpolation operator;
step E, calculating a stratum triaxial main stress value under the middle local coordinate of the reservoir at any position in the target area and a direction component thereof based on the stratum stress tensor under the middle global coordinate of the reservoir at any position in the target area obtained in the step D;
step E, calculating a flow:
according to the stratum stress tensor under the central global coordinate of the reservoir at any position in the target area, calculating the stratum stress tensor eigenvalue and eigenvector matrix under the central local coordinate of the reservoir at any position in the target area by using an equation (8) through the matrix eigenvalue and eigenvector operation;
extracting the maximum horizontal principal stress value, the minimum horizontal principal stress value, the vertical principal stress value and each principal stress direction component of the stratum under the middle local coordinate of the reservoir at any position in the target area from the stratum stress tensor eigenvalue and the eigenvector matrix under the middle local coordinate of the reservoir at any position in the target area by using equations (9) and (10);
[V,D]=eig(σmid|global) (8)
V=[σhmid,σHmid,σvmid] (9)
in the formula: eig is a matrix eigenvalue and eigenvector operator; v is a stratum stress tensor eigenvalue matrix Pa under the middle local coordinate of the reservoir at any position in the target area; d is a formation stress tensor eigenvector matrix under the middle local coordinate of the reservoir at any position in the target area, and is dimensionless; sigmaHmid、σhmid、σvmidThe maximum horizontal main stress value, the minimum horizontal main stress value and the vertical main stress value Pa of the stratum under the middle local coordinate of the reservoir at any position in the target area are obtained; x is the number ofhmid、yhmid、zhmidThe minimum horizontal principal stress direction component of the stratum under the middle local coordinate of the reservoir at any position in the target area is dimensionless; x is the number ofHmid、yHmid、zHmidThe method is characterized in that the method is a formation maximum horizontal principal stress direction component under the middle local coordinate of a reservoir at any position in a target region and is dimensionless; x is the number ofvmid、yvmid、zvmidThe vertical principal stress direction component of the stratum under the middle local coordinate of the reservoir at any position in the target area is dimensionless;
f, drawing a stratum maximum horizontal main stress value, a minimum horizontal main stress value, a vertical main stress value distribution cloud chart and maximum and minimum horizontal stress direction vector charts under local coordinates in the target region;
and G, determining the non-uniform distribution condition of the triaxial stress field of the stratum at any position in the target region according to the stratum stress tensor component distribution cloud picture under the global coordinate in the target region, the stratum maximum horizontal main stress value, the minimum horizontal main stress value and the vertical main stress value distribution cloud picture under the local coordinate in the target region, and the maximum and minimum horizontal stress direction vector pictures.
Example 1
A method for calculating a nonuniform stress field of a deep shale complex formation comprises the following steps:
actual data of 6 drilled wells in a deep shale gas reservoir area with a certain complex structure are shown in table 1.
TABLE 1 actual data of 6 drilled wells in a deep shale gas reservoir area of a complex structure
The calculation flow diagram of the method according to the invention (as shown in fig. 1) develops an example calculation:
firstly, the triaxial stress gradient of the stratum under the local coordinate of each well position is calculated by using the drilled well data in the target area.
The method comprises the following specific steps: inputting formation stress data obtained by measuring drilled wells in a target area, wherein the formation stress data comprises a maximum horizontal main stress value, a minimum horizontal main stress value and a vertical main stress value; secondly, inputting the coordinate data of the drilled well position in the target area and the vertical depth of the stratum stress measuring point of each well, and drawing a well position distribution diagram as shown in figure 2; thirdly, calculating the three-axis principal stress gradient of the stratum at each well position by using the equation (1), comprising the following steps: maximum horizontal principal stress gradient, minimum horizontal principal stress gradient, vertical principal stress gradient, as shown in table 2.
TABLE 2 three-axis principal stress gradient of formation at each well location
And then, calculating the triaxial stress value of the stratum under the middle local coordinate of the reservoir at each well position by using the middle vertical depth data of the reservoir in the target area.
The method comprises the following specific steps: inputting vertical depth data of the middle part of a reservoir in a target area: 2200 m; secondly, calculating the stratum triaxial stress value under the middle local coordinate of the reservoir at each well position by using an equation (2), wherein the equation comprises the following steps: the maximum horizontal principal stress value, the minimum horizontal principal stress value, and the vertical principal stress value are shown in table 3; thirdly, assembling the triaxial stress values of the stratum under the local coordinates of the middle part of the reservoir at the position of the i-type well into a tensor form by using an equation (3).
TABLE 3 triaxial stress values of the formation at the middle local coordinates of the reservoir at each well location
And then, calculating the stratum stress tensor component under the central global coordinate of the reservoir at each well position by using a tensor coordinate system conversion algorithm.
The method comprises the following specific steps: firstly, inputting the maximum horizontal main stress direction of each well position obtained by drilling and setting well measurement in a target area, namely the included angle between the maximum horizontal main stress direction and the x axis of the global coordinate system; respectively calculating the formation stress tensor components under the central global coordinate of the reservoir at each well position by using an equation (5) through a tensor coordinate system conversion algorithm, as shown in a table 4; and thirdly, assembling the formation stress tensor components under the central global coordinate of the reservoir at each well position into a tensor form by using an equation (4).
TABLE 4 formation stress tensor components at the central global coordinates of the reservoir at each well location
And then, calculating the formation stress tensor component under the central global coordinate of the reservoir at any position in the target area by using a natural adjacent point three-dimensional interpolation algorithm.
The method comprises the following specific steps: calculating the stratum stress tensor component under the central global coordinate of the reservoir at any position in a target area by using an equation (7) through a natural adjacent point three-dimensional interpolation method according to the stratum stress tensor component under the central global coordinate of the reservoir at each well position, and drawing a distribution cloud picture; assembling the formation stress tensor components under the global coordinate of the middle part of the reservoir at any position in the target area into a tensor form by using an equation (6); and thirdly, drawing a distribution cloud picture of each component of the formation stress tensor under the global coordinate in the target area, as shown in fig. 3.
And then, calculating the stratum triaxial stress value and the maximum principal stress direction under the middle local coordinate of the reservoir at any position in the target area by using a tensor coordinate system conversion algorithm.
The method comprises the following specific steps: calculating a stratum stress tensor eigenvalue and an eigenvector matrix under the central local coordinate of the reservoir at any position in the target area by using an equation (8) through the matrix eigenvalue and eigenvector operation according to the stratum stress tensor under the central global coordinate of the reservoir at any position in the target area; extracting the maximum horizontal principal stress value, the minimum horizontal principal stress value, the vertical principal stress value and each principal stress direction component of the stratum under the middle local coordinate of the reservoir at any position in the target area from the stratum stress tensor eigenvalue and the eigenvector matrix under the middle local coordinate of the reservoir at any position in the target area by using equations (9) and (10); and thirdly, drawing a distribution cloud picture of the maximum horizontal principal stress value, the minimum horizontal principal stress value and the vertical principal stress value of the stratum under the local coordinate in the target area, and a direction vector picture of the maximum horizontal stress and the minimum horizontal stress respectively as shown in the figures 4 and 5.
The method is specially used for solving the problem of insufficient data acquisition means of the stress field of the deep shale complex formation, and provides a calculation method of the inhomogeneous stress field of the deep shale complex formation by combining a tensor coordinate system conversion algorithm and a natural adjacent point three-dimensional interpolation method. Because the method can calculate the inhomogeneous distribution condition of the triaxial stress field of the stratum at any position in the target area only by depending on limited data such as the triaxial stress value, the maximum horizontal main stress direction and the like of the stratum drilled with the well in the target area without large-scale geological structure mechanical modeling, the method solves the problems that the stratum stress field of the complex structure of the deep shale changes faster in a smaller area and a fast and accurate inhomogeneous stratum stress field calculation method is lacked.
Although the present invention has been described with reference to the above embodiments, it should be understood that the present invention is not limited to the above embodiments, and those skilled in the art can make various changes and modifications without departing from the scope of the present invention.