CN-121993149-A - Method and system for determining comprehensive anisotropy index

CN121993149ACN 121993149 ACN121993149 ACN 121993149ACN-121993149-A

Abstract

The invention discloses a method and a system for determining a comprehensive anisotropy index, wherein the method comprises the steps of measuring basic parameters, wherein the basic parameters comprise a borehole track parameter, a drill string structure parameter and a stratum dip angle parameter; and calculating the drill bit anti-tilting force of the drilling tool in the drilled stratum by utilizing the pre-bending BHA three-dimensional mechanical model according to the basic parameters, taking the drill bit anti-tilting force under the maximum drilling pressure as the deflecting force of the drilled stratum, and inverting the stratum anisotropy index based on the deflecting force. The invention can comprehensively consider drilling characteristics and the pre-bending structure, thereby forming a comprehensive anisotropic index determination scheme.

Inventors

CHEN XIUPING
LI SHUANGGUI
ZHAO CHANGJU
ZHANG CHAOQUN
HUA SONG
ZHANG XIAOLONG

Assignees

中国石油化工股份有限公司
中国石油化工股份有限公司西北油田分公司

Dates

Publication Date: 20260508
Application Date: 20241104

Claims (10)

1. A method for determining an integrated anisotropy index, comprising: Measuring basic parameters including borehole trajectory parameters, drill string structural parameters and formation dip parameters; Calculating the drill bit anti-tilting force of the drilling tool in the drilled stratum by utilizing a pre-bending BHA three-dimensional mechanical model according to the basic parameters; And taking the drill bit anti-tilting force under the maximum drilling pressure as the deflecting force of the drilled stratum, and inverting the stratum anisotropy index based on the deflecting force.
2. The method of claim 1, wherein the step of determining the position of the substrate comprises, The well track parameters comprise well depths, well angles, azimuth angles and dog legs under corresponding well depths; the drill string structural parameters comprise the bent angle and the position of a screw rod or a pre-bent short joint, the outer diameter, the inner diameter, the length and the density of a drilling tool, and the drilling tool comprises a drill bit, a drill collar, a stabilizer and an adapter; The formation dip parameters include the dip of the drilled formation and the dip of the formation to be drilled, as measured in the first step.
3. The method of claim 2, wherein in the step of calculating the anti-slop force of the drill bit in the drilled formation using the pre-curved BHA three-dimensional mechanical model based on the base parameters, And calculating the drill bit inclination preventing force of the drilled stratum by utilizing the pre-bending BHA three-dimensional mechanical model according to the maximum bit pressure corresponding to the drilling tool when the drilling tool is not inclined in the drilled stratum.
4. The method of claim 3, wherein the step of, According to the basic parameters, determining the mechanical parameters of the drill string under the maximum drilling pressure corresponding to the current well inclination angle and the non-inclination increase, wherein the mechanical parameters of the drill string comprise the axial pressure at the bottom end of the drill string and the contact pressure between the stabilizer and the well wall; According to the current well inclination angle, the mechanical parameters and the basic parameters of the drill string under the current maximum drilling pressure, calculating the lateral force of the drill bit under any tool face angle by utilizing a pre-bending BHA three-dimensional mechanical model; calculating combined oblique force and combined azimuth force according to the lateral force of the drill bit under any tool face angle; And calculating the drill bit anti-tilting force according to the combined tilting force and the combined azimuth force.
5. The method of claim 3 or 4, wherein the pre-curved BHA three-dimensional mechanical model is represented by the following expression: Wherein f a 、f t represents the axial and tangential friction coefficients, x represents the coordinate along the axis of the drill string with the bottom end of the ith drill string as a starting point, E i represents the elastic modulus of the ith drill string, I i represents the section moment of inertia of the ith drill string, u i represents the deflection of the ith drill string in the y direction, v i represents the deflection of the ith drill string in the z direction, M ti represents the torque exerted on the ith drill string, q i represents the weight per unit length of the ith drill string in the drilling fluid, alpha i represents the well inclination angle of the well section where the ith drill string is located, B i represents the axial pressure of the bottom end of the ith drill string, L i represents the length of the ith drill string, N i represents the contact pressure between the lower end of the ith drill string and the well wall, and D w represents the diameter of the well bore; Bit side force was calculated using the following expression: wherein ω represents a tool face angle, F α(ω) , Respectively representing bit side forces in different directions at the toolface angle ω.
6. The method of any one of claims 3-5, wherein the combined oblique force, combined azimuth force, drill bit anti-oblique force are calculated using the following expression: Wherein F sα represents a combined oblique force, The resultant force is denoted by F s , the drill bit tilting prevention force is denoted by n, and the total calculated number of times obtained by equally dividing the drill bit rotation by one turn is denoted by n.
7. The method according to any one of claims 1 to 6, wherein the step of taking the bit anti-dip force at the maximum drilling pressure as a whipstock force of the drilled formation and inverting the formation anisotropy index based thereon comprises: Establishing a whipstock calculation formula for representing the relation among the formation whipstock, the weight on bit, the formation anisotropy index and the formation dip angle; And obtaining the current stratum anisotropy index by using the calculation method of the deflecting force according to the drill bit tilting prevention force under the maximum drilling pressure, the inclination angle of the drilled stratum and the maximum drilling pressure of the drilled stratum.
8. The method of claim 7, wherein the whipstock calculation is represented by the following expression: Wherein F m represents the formation making bias, W represents the weight on bit, h represents the formation anisotropy index, c=pi/180, β represents the formation dip angle, and α represents the well dip angle.
9. The method according to any one of claims 1-8, further comprising: And determining reasonable weight on bit required when drilling the stratum to be drilled according to the stratum anisotropy index.
10. A system for determining an integrated anisotropy index, wherein the system is configured to implement the method of any of claims 1-9, wherein the system comprises: A measurement device configured to measure basic parameters including wellbore trajectory parameters, drill string structure parameters, and formation dip parameters; The drill bit anti-tilting force calculation module of the drilled stratum is configured to calculate the drill bit anti-tilting force of the drilling tool in the drilled stratum by utilizing a pre-bending BHA three-dimensional mechanical model according to basic parameters; And the comprehensive anisotropy index generation module is used for taking the drill bit anti-inclination force under the maximum drilling pressure as the deflecting force of the drilled stratum and inverting the stratum anisotropy index based on the drill bit anti-inclination force.

Description

Method and system for determining comprehensive anisotropy index Technical Field The invention relates to the technical field of oilfield drilling, in particular to a method and a system for determining an integrated anisotropy index. Background For ultra-deep and ultra-deep wells, the fast anti-whipping is one of the important concerns, not only directly related to the well quality, but also closely related to the dynamic safety of the drill string. Although the vertical drilling system plays a good role in drilling ultra-deep wells and ultra-deep wells, the use cost is high. The pre-bending dynamics anti-diagonal drilling quick technology utilizes the BHA with the pre-bending structure to perform anti-diagonal operation, has large anti-diagonal force and obvious accelerating effect, has obvious comprehensive economic benefit and has extremely strong competitiveness in some areas although the anti-diagonal drilling quick effect is slightly worse than that of a vertical drilling system. How to determine the maximum weight-on-bit, i.e., the appropriate weight-on-bit for a given pre-bent BHA, based on formation characteristics and pre-bent BHA structural parameters has not been addressed. Of these, the most critical is the inability to know the overall anisotropy index of the formation (including the anisotropic nature of the drill bit and the formation). In the literature technology entitled "a method for expressing drilling characteristics of drill bit and stratum anisotropy", rock anisotropy indexes are obtained and classified according to acting forces in all directions and drilling speeds in all directions of the drill bit. In addition, in the literature technique entitled "calculation and application of formation making Tilt force", a formation anisotropy index formula is derived, which is applicable to calculating formation anisotropy indexes given bit offset angle, steady well offset angle, formation dip angle. However, the method for determining the comprehensive anisotropy index provided by the prior document is mainly based on an empirical formula or a theoretical formula, related parameters are difficult to obtain, the anisotropy index of the stratum is determined without combining the actual well inclination angle, the stratum inclination angle and the steady inclined acting force of drilling, and meanwhile, the drilling tool combination structure is not considered. In view of the foregoing, there is a need in the art to provide a comprehensive anisotropy index determination scheme that considers both drilling characteristics and pre-bent structure. Disclosure of Invention It is an object of the present invention to provide a comprehensive anisotropy index determination scheme that considers both drilling characteristics and pre-bent structure. In order to solve the technical problems, the embodiment of the invention provides a method for determining an integrated anisotropy index, which comprises the steps of measuring basic parameters including a borehole trajectory parameter, a drill string structure parameter and a stratum inclination angle parameter, calculating a drill bit anti-inclination force of a drilling tool in a drilled stratum by using a pre-bending BHA three-dimensional mechanical model according to the basic parameters, taking the drill bit anti-inclination force under the maximum drilling pressure as a deflecting force of the drilled stratum, and inverting the stratum anisotropy index based on the drill bit anti-inclination force. Preferably, the well track parameters comprise well depth and well inclination, azimuth and dog leg angle under the corresponding well depth, the drill string structure parameters comprise the bent angle and position of a screw or a pre-bent short joint, and the outer diameter, inner diameter, length and density of a drilling tool, the drilling tool comprises a drill bit, a drill collar, a stabilizer and a conversion joint, and the stratum inclination parameters comprise the inclination of the stratum to be drilled and the inclination of the stratum to be drilled, which are measured in the first step. Preferably, in the step of calculating the drill bit anti-tilting force of the drilling tool in the drilled stratum by utilizing the pre-bending BHA three-dimensional mechanical model according to the basic parameters, the drill bit anti-tilting force of the drilled stratum is calculated by utilizing the pre-bending BHA three-dimensional mechanical model according to the maximum bit pressure corresponding to the drilling tool when the drilling tool is not tilted in the drilled stratum. Preferably, according to basic parameters, determining drill string mechanical parameters under the corresponding maximum drilling pressure when the current well inclination angle and the inclination are not increased, wherein the drill string mechanical parameters comprise the axial pressure of the bottom end of a drill string and the contact pressure of a stabilizer and a