Method and system for determining reasonable bit pressure of pre-bent BHA

Abstract

The invention discloses a method and system for determining reasonable bit pressure of a pre-bending BHA, and the method comprises the steps: measuring basic parameters which comprise a well track parameter, a drill column structure parameter and a stratigraphic dip angle parameter; according to the basic parameters, by means of a pre-bending BHA three-dimensional mechanical model, the drill bit deviation prevention force of the drilling tool under the maximum drilling pressure in the drilled stratum is calculated; taking the anti-deflection force of the drill bit under the maximum bit pressure as the deflecting force of the drilled stratum, and inverting the anisotropy index of the stratum based on the deflecting force; and according to the anisotropy index of the stratum, the deflecting force of the stratum to be drilled under different bit pressures is calculated, according to the pre-bending BHA three-dimensional mechanical model, the deflection prevention force of the drill bit of the stratum to be drilled under different bit pressures is calculated, and based on this, the reasonable bit pressure is optimized. According to the method, bit pressure selection is carried out by considering the effective deviation prevention force of the pre-bending BHA, and the reasonable bit pressure is reasonably deduced.

Description

Technical Field

[0001] This invention relates to the field of oilfield drilling technology, and in particular to a method and system for determining the appropriate drilling pressure for pre-bent BHA. Background Technology

[0002] For ultra-deep and extra-deep wells, preventing deviation and ensuring rapid drilling has always been a key concern, directly impacting wellbore quality and the dynamic safety of the drill string. While vertical drilling systems have proven effective in ultra-deep and extra-deep wells, their operating costs are very high.

[0003] Pre-bending dynamic anti-deviation and fast drilling technology utilizes pre-bending BHAs for anti-deviation operations, resulting in high anti-deviation force and significant speed-up. Although its anti-deviation and fast drilling effect is slightly inferior to vertical drilling systems, its overall economic benefits are significant, making it highly competitive in some regions. However, determining the maximum drilling pressure (BP) based on formation characteristics and the structural parameters of the pre-bending BHA—that is, the appropriate BP for a given pre-bending BHA—has remained unsolved.

[0004] In the literature titled "Experimental Study on Pre-bending Dynamic Anti-deviation Fast Drilling Technology," based on field experiments of pre-bending dynamic anti-deviation fast drilling technology, it was found that the drilling pressure increase is over 50% compared to pendulum drill string assemblies. Additionally, in the literature titled "Optimization and Application of Conventional Drill String Assemblies for Anti-deviation Fast Drilling Pressure," based on the bending theory of longitudinal and transverse bending beams and tubing, considering the influence of formation build-up force on well deviation, and using the minimum comprehensive force of the drill bit as the criterion, and with the buckling critical force as the constraint, an optimal model for conventional drill string assemblies to achieve anti-deviation fast drilling pressure in vertical wells was established.

[0005] However, the methods for determining reasonable drilling pressure provided in the existing literature are mainly based on experimental exploration. Theoretically, they do not take into account drilling characteristics such as the actual well inclination angle, formation dip angle, and formation anisotropy index. At the same time, they do not consider the limit drilling pressure for preventing deviation by pre-bending structures.

[0006] In summary, the existing technology needs to provide a reasonable drilling pressure determination scheme that simultaneously considers drilling characteristics and pre-bending structure. Summary of the Invention

[0007] The purpose of this invention is to provide a reasonable drilling pressure determination scheme that simultaneously considers drilling characteristics and pre-bending structure.

[0008] To address the aforementioned technical problems, this invention provides a method for determining a reasonable drilling pressure for a pre-bent BHA (Boiler Harness), comprising: measuring basic parameters, including wellbore trajectory parameters, drill string structure parameters, and formation dip angle parameters; calculating the drill bit anti-directional force under the maximum drilling pressure in the drilled formation based on the basic parameters using a three-dimensional mechanical model of the pre-bent BHA; using the drill bit anti-directional force under the maximum drilling pressure as the directional force for the drilled formation, and inverting the formation anisotropy index based on this; calculating the directional force for the formation to be drilled under different drilling pressures based on the formation anisotropy index, and calculating the drill bit anti-directional force for the formation to be drilled under different drilling pressures based on the three-dimensional mechanical model of the pre-bent BHA, and selecting a reasonable drilling pressure based on this.

[0009] Preferably, the wellbore trajectory parameters include the well depth and the inclination angle, azimuth angle, and dogleg angle at the corresponding well depth; the drill string structure parameters include the bend angle and position of the screw or pre-bent connector, as well as the outer diameter, inner diameter, length, and density of the drill string, which includes the drill bit, drill collar, stabilizer, and adapter; the formation dip angle parameters include the dip angle of the drilled formation and the dip angle of the formation to be drilled.

[0010] Preferably, based on the basic parameters, the drill bit anti-deviation force under a specified drilling pressure is calculated using a pre-bent BHA three-dimensional mechanical model. This includes: determining the current well inclination angle and drill string mechanical parameters under a specified drilling pressure based on the basic parameters, wherein the drill string mechanical parameters include the axial pressure at the bottom of the drill string and the contact pressure between the stabilizer and the wellbore; calculating the drill bit lateral force at any tool face angle using the pre-bent BHA three-dimensional mechanical model based on the current well inclination angle, the drill string mechanical parameters under a specified drilling pressure, and the basic parameters; calculating the combined build-up force and the combined azimuth force based on the drill bit lateral force at the arbitrary tool face angle; and calculating the drill bit anti-deviation force and its direction based on the combined build-up force and the combined azimuth force.

[0011] Preferably, the drill bit anti-deviation force for the drilled formation is calculated based on the maximum drilling pressure corresponding to the drill bit when it does not increase the deviation in the drilled formation; and the drill bit anti-deviation force for the formation to be drilled under the specified alternative drilling pressure conditions is calculated based on the well inclination angle of the section to be drilled and at least one alternative drilling pressure data.

[0012] Preferably, the three-dimensional mechanical model of the pre-bent BHA is represented by the following expression:

[0013]

[0014] Among them, f a f t represents the friction coefficients in the axial and tangential directions, respectively; x represents the coordinate along the drill string axis, with the bottom end of the i-th drill string as the starting point; E i I represents the elastic modulus of the i-th drill string segment; i u represents the moment of inertia of the i-th segment of the drill string;i v represents the deflection of the i-th drill string along the y-direction; i M represents the deflection of the i-th drill string along the z-direction; ti q represents the torque experienced by the i-th segment of the drill string; i α represents the weight per unit length of the i-th drill string segment in the drilling fluid; i B represents the well inclination angle of the well section containing the i-th drill string segment; i L represents the axial pressure at the bottom of the i-th drill string segment; i N represents the length of the i-th drill string segment; i D represents the contact pressure between the lower end of the i-th drill string and the wellbore; w Indicates the wellbore diameter;

[0015] The lateral force of the drill bit is calculated using the following expression:

[0016]

[0017] Where ω represents the tool face angle, F α(ω) , These represent the lateral forces of the drill bit in different directions under the tool face angle ω.

[0018] Preferably, the combined azimuth force, the drill bit anti-deviation force, and the direction of the anti-deviation force are calculated using the following expressions:

[0019]

[0020] Among them, F sα Indicates the combined oblique force. F represents the resultant azimuth force. s α represents the anti-skew force of the drill bit. s The direction of the anti-swerving force is indicated by , and n represents the total number of calculation points obtained by dividing one revolution of the drill bit into equal parts.

[0021] Preferably, the step of using the drill bit anti-deviation force under the maximum drilling pressure as the drilling force of the drilled formation, and inverting the formation anisotropy index based on this, includes: establishing a drilling force calculation formula characterizing the relationship between formation drilling force, drilling pressure, formation anisotropy index, and formation dip angle; obtaining the current formation anisotropy index using the drilling force calculation formula based on the drill bit anti-deviation force under the maximum drilling pressure, the dip angle of the drilled formation, and the maximum drilling pressure of the drilled formation; and calculating the drilling force of the formation to be drilled under different drilling pressures based on the formation anisotropy index, including: calculating the formation drilling force under different specified drilling pressure conditions using the drilling force calculation formula based on the current formation anisotropy index, the dip angle of the formation to be drilled, and the specified drilling pressure.

[0022] Preferably, the formula for calculating the inclined force is expressed using the following expression:

[0023]

[0024] Among them, F m denoted by , W represents the drilling pressure, h represents the formation anisotropy index, c = π / 180, β represents the formation dip angle, and α represents the well inclination angle.

[0025] Preferably, a reasonable drilling pressure is selected based on the formation build-up force and drill bit anti-deviation force of the formation to be drilled under different drilling pressures. This includes: calculating the effective anti-deviation force of the formation to be drilled under different drilling pressures based on the formation build-up force and drill bit anti-deviation force of the formation to be drilled under different drilling pressures; performing curve fitting on the effective anti-deviation force of the formation to be drilled under different drilling pressures to obtain a curve showing the relationship between drilling pressure and effective anti-deviation force; identifying a reasonable drilling pressure based on the curve showing the relationship between drilling pressure and effective anti-deviation force, wherein the drilling pressure corresponding to zero effective anti-deviation force is extracted from the curve showing the relationship between drilling pressure and effective anti-deviation force, thereby obtaining a reasonable drilling pressure for the formation to be drilled.

[0026] Preferably, the effective anti-deviation force under the corresponding drilling pressure is obtained by calculating the difference between the drill bit anti-deviation force and the formation deflection force under the same drilling pressure.

[0027] On the other hand, embodiments of the present invention provide a system for determining a reasonable drilling pressure for a pre-bent BHA (Boiled Harness Automated) drilling system. The system is used to implement the method described above. The system includes: a measuring device configured to measure basic parameters, including wellbore trajectory parameters, drill string structure parameters, and formation dip angle parameters; a drill bit anti-directional force calculation module for drilled formations, configured to calculate the drill bit anti-directional force under maximum drilling pressure in the drilled formation based on the basic parameters and using a three-dimensional mechanical model of the pre-bent BHA; a formation anisotropy index generation module, configured to use the drill bit anti-directional force under the maximum drilling pressure as the directional force for the drilled formation, and based on this, invert the formation anisotropy index; and a drilling pressure optimization module, configured to calculate the directional force for the formation to be drilled under different drilling pressures based on the formation anisotropy index, and to calculate the drill bit anti-directional force for the formation to be drilled under different drilling pressures based on the three-dimensional mechanical model of the pre-bent BHA, and based on this, optimize a reasonable drilling pressure.

[0028] Compared with the prior art, one or more embodiments of the above solutions may have the following advantages or beneficial effects:

[0029] This invention proposes a method and system for determining the appropriate drilling pressure (DP) for a pre-bent borehole stabilizer (BHA). Based on measured wellbore trajectory parameters, drill string structure parameters, and formation dip angle, the method and system invert the anisotropy index of the formation using the drilled formation dip angle, well inclination angle, and the anti-deviation force of the pre-bent BHA. Subsequently, it determines the effective anti-deviation force of the pre-bent BHA in the formation to be drilled under different DPs. Finally, it determines the maximum DP when the effective anti-deviation force is greater than zero and uses this as the applicable DP for the pre-bent dynamic anti-deviation fast bottom drilling tool assembly. This invention selects the DP by considering the effective anti-deviation force of the pre-bent BHA, reasonably inferring the appropriate DP. It takes into account both the anti-deviation force of the pre-bent BHA and the formation build-up force, making it simple, easy to implement, and low-cost, suitable for widespread use, unlike existing technologies that mainly rely on trial and error to determine the appropriate DP, which lacks evaluation criteria once the formation changes. Secondly, this invention is applicable to all dual-stabilizer pre-bent BHAs with bend angles between 0.75 and 1.5°. Furthermore, this invention is applicable to situations where the maximum well inclination angle is less than 4°.

[0030] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the description, claims, and drawings. Attached Figure Description

[0031] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with the embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0032] Figure 1 This is a schematic diagram illustrating the steps of a method for determining the appropriate drilling pressure for a pre-bent BHA according to an embodiment of this application.

[0033] Figure 2 This is a schematic flowchart illustrating the method for determining the appropriate drilling pressure for pre-bent BHA according to an embodiment of this application.

[0034] Figure 3 This is an example diagram of the pre-bent BHA structure in the method for determining the reasonable drilling pressure of the pre-bent BHA according to an embodiment of this application.

[0035] Figure 4 This is an example diagram illustrating the effect of calculating the anti-swerving force of the pre-bent BHA in the method for determining the reasonable drilling pressure of the pre-bent BHA according to an embodiment of this application.

[0036] Figure 5 This is a schematic diagram illustrating the effect of the relationship curve between drilling pressure and effective anti-deviation force in the first example of the method for determining reasonable drilling pressure for pre-bent BHA according to an embodiment of this application.

[0037] Figure 6 This is a schematic diagram illustrating the effect of the relationship curve between drilling pressure and effective anti-deviation force in the second example of the method for determining reasonable drilling pressure for pre-bent BHA according to an embodiment of this application.

[0038] Figure 7 This is a schematic diagram of the system for determining the appropriate drilling pressure for pre-bent BHA according to an embodiment of this application. Detailed Implementation

[0039] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings and examples, so that the process of how the present invention uses technical means to solve technical problems and achieve technical effects can be fully understood and implemented accordingly. It should be noted that, as long as there is no conflict, the various embodiments and features in the various embodiments of the present invention can be combined with each other, and the resulting technical solutions are all within the protection scope of the present invention.

[0040] Furthermore, the steps illustrated in the flowcharts of the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Also, although a logical order is shown in the flowcharts, in some cases the steps shown or described may be performed in a different order than that shown here.

[0041] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments. Unless the context clearly indicates otherwise, the singular forms “a” and “an” as used herein are also intended to include the plural. It should also be understood that the terms “comprising” and / or “including” as used herein specify the presence of the stated features, integers, steps, operations, units, and / or components, without excluding the presence or addition of one or more other features, integers, steps, operations, units, components, and / or combinations thereof.

[0042] To address one or more of the technical problems mentioned in the background section, this application provides a method and system for determining the appropriate drilling pressure for pre-bent BHAs. This method and system, based on pre-bending dynamics and considering factors such as the pre-bending structure, formation dip angle, and formation anisotropy index, determines the appropriate drilling pressure, forming a good anti-deviation and fast drilling application scheme. It has significant practical application value in protecting tools and ensuring deviation control effects.

[0043] Example 1

[0044] Figure 1 This is a schematic diagram illustrating the steps of a method for determining the appropriate drilling pressure for a pre-bent BHA according to an embodiment of this application. Figure 2 This is a schematic flowchart illustrating the method for determining the appropriate drilling pressure for pre-bent BHA according to an embodiment of this application. The following is in conjunction with... Figure 1 and Figure 2The specific steps of the method for determining the reasonable drilling pressure of a pre-bent BHA (also known as the "reasonable drilling pressure determination method") described in the embodiments of the present invention will be explained.

[0045] Step S110: Measure basic parameters. In step S110, the basic parameters include: actual wellbore trajectory parameters, drill string structure parameters, and formation dip angle parameters.

[0046] Specifically, the actual wellbore trajectory parameters include at least: well depth and the inclination angle, azimuth angle, and dogleg angle at the corresponding well depth. The drill string structure parameters include at least: the bend angle and position of the screw or pre-bent connector, and the outer diameter, inner diameter, length, and density of the drill string. In this embodiment of the invention, the drill string includes, but is not limited to: drill bit, drill collar, stabilizer, and adapter. Additionally, the formation dip angle parameters include at least: the dip angle of the drilled formation and the dip angle of the formation to be drilled.

[0047] In this embodiment of the invention, the pre-bent BHA is a double-stabilizer pre-bent BHA, and the pre-bent drill bit used is composed of a single-bent screw with a stabilizer or a special pre-bent short joint.

[0048] In step S110, the structural parameters of the pre-bent bottom auger assembly (pre-bent BHA), i.e., the drill string structural parameters, can be measured using measuring tools such as laser measuring instruments and specialized gauges. Actual wellbore trajectory parameters can be measured using tools such as triaxial accelerometers, fluxgate sensors, MWD, single-point inclinometers, and multi-point inclinometers. Additionally, the dip angles of drilled formations and the formations to be drilled can be determined based on seismic exploration data or other logging data.

[0049] After completing the basic parameter measurements, proceed to step S120.

[0050] Step S120: Based on the basic parameters, the drill bit anti-directional force under the maximum drilling pressure when the drill bit does not increase the directional force in the drilled formation is calculated using the three-dimensional mechanical model of the pre-bent BHA, thereby determining the drill bit anti-directional force of the pre-bent BHA in the drilled formation.

[0051] Specifically, in embodiments of the present invention, the anti-deviation force of the drill bit under a specified drilling pressure can be calculated based on basic parameters using a pre-bent BHA three-dimensional mechanical model.

[0052] In one embodiment, based on basic parameters, the drill bit anti-deviation force of the pre-bent BHA under the maximum drilling pressure (DBP) in the drilled formation without directional increase is calculated using a three-dimensional mechanical model. The maximum DBP without directional increase can be obtained from historical DBP data of the drilled well.

[0053] Specifically, based on the basic parameters, the drill string mechanical parameters under the current well inclination angle and specified drilling pressure are determined. These parameters include the axial pressure at the bottom of the drill string and the contact pressure between the stabilizer and the wellbore. Then, based on the drill string mechanical parameters under the current well inclination angle and specified drilling pressure, and the basic parameters, the lateral force of the drill bit at any toolface angle is calculated using the pre-bent BHA three-dimensional mechanical model. Next, based on the lateral force of the drill bit at any toolface angle, the combined build-up force and combined azimuth force are calculated. Finally, based on the current combined build-up force and current combined azimuth force, the drill bit anti-deviation force and its direction are calculated.

[0054] In step S120, the specified drill pressure refers to the maximum drill pressure corresponding to the drill string (pre-bent BHA) without increasing the directional deviation in the drilled formation. At this time, in the process of calculating the drill bit anti-directional deviation force of the drilled formation, it is necessary to first determine the drill string mechanical parameters corresponding to the current maximum drill pressure, that is, to calculate the drill bit anti-directional deviation force of the drilled formation based on the maximum drill pressure corresponding to the drill string without increasing the directional deviation in the drilled formation.

[0055] Furthermore, in this embodiment of the invention, the three-dimensional mechanical model of the pre-bent BHA is represented by the following expression:

[0056]

[0057] Among them, f a f t represents the friction coefficients in the axial and tangential directions, respectively; x represents the coordinate along the drill string axis, with the bottom end of the i-th drill string as the starting point; E i I represents the elastic modulus of the i-th drill string segment, in Pa; i The moment of inertia of the i-th segment of the drill string is expressed in meters. 4 ;u i This represents the deflection of the i-th drill string along the y-direction, in meters (m); v i M represents the deflection of the i-th drill string along the z-direction, in meters (m). ti q represents the torque on the i-th segment of the drill string, in N·m; i α represents the weight per unit length of the i-th drill string segment in the drilling fluid, in N / m; i B represents the well inclination angle of the i-th drill string segment, in rad; i L represents the axial pressure (positive pressure) at the bottom of the i-th drill string segment, in N; i N represents the length of the i-th drill string segment, in meters (m); i N represents the contact pressure between the lower end of the i-th drill string and the wellbore. When there is no contact, N is... i =0, unit is N; D w This indicates the wellbore diameter, measured in meters (m).

[0058] The lateral force of the drill bit is calculated using the following expression:

[0059]

[0060] Where ω represents the tool face angle, F α(ω) , These represent the lateral forces of the drill bit in different directions under the tool face angle ω.

[0061] Using the above expressions (1)-(4), the internal mechanical correlation characteristics of each section of the drill string can be listed. Combined with the measurement results of the basic parameters, the lateral force F of the drill bit under the maximum drilling pressure condition corresponding to the drill string (pre-bent BHA) in the drilled formation without increasing the inclination can be calculated using expressions (5) and (6). α(ω) ,

[0062] Furthermore, in this embodiment of the invention, the combined azimuth force, the drill bit anti-deviation force, and the direction of the anti-deviation force are calculated using the following expressions:

[0063]

[0064] Among them, F sα Indicates the combined oblique force. F represents the resultant azimuth force. s α represents the anti-skew force of the drill bit. s The direction of the anti-swerving force is indicated by n, which represents the total number of calculation points obtained by dividing the drill bit into equal parts for one revolution (360°).

[0065] Therefore, after calculating the drill bit lateral force under the maximum drilling pressure condition corresponding to the drilled formation without increasing the directional deviation, substituting the current drill bit lateral force data into expressions (7)-(10) allows for the direct calculation of the drill bit anti-directional deviation force and the corresponding anti-directional deviation force direction for the drilled formation. See [link to relevant documentation]. Figure 4 .

[0066] After completing the drill bit anti-deviation force calculation for the drilled strata, proceed to step S130.

[0067] In step S130, the drill bit anti-directional force under the maximum drilling pressure of the drilled formation calculated in step S120 is used as the directional force of the drilled formation, and the formation anisotropy index is inverted based on the directional force of the drilled formation.

[0068] In step S130, firstly, a formula for calculating the build-up force is established to characterize the relationship between the formation build-up force, drilling pressure, formation anisotropy index, and formation dip angle. Then, based on the drill bit anti-deviation force calculation results obtained in step S120 under the maximum drilling pressure, the dip angle of the drilled formation, and the maximum drilling pressure of the drilled formation, the current formation anisotropy index is obtained using the above formula for calculating the build-up force.

[0069] In this embodiment of the invention, the formula for calculating the inclined force is expressed by the following expression:

[0070]

[0071] Among them, F m denoted by , W represents the drilling pressure, h represents the formation anisotropy index, c = π / 180, β represents the formation dip angle, and α represents the well inclination angle.

[0072] When the drill bit is stable, the anti-deviation force of the drill bit in the drilled formation can be considered to be approximately equal to the formation deflection force of the drilled formation. Therefore, the anti-deviation force of the drill bit in the drilled formation calculated in step S120 can be equal to the formation deflection force of the drilled formation. This force can be substituted into the expression (11) that represents the deflection force calculation formula. Then, combined with the formation dip angle of the drilled formation, the well inclination angle of the drilled section in the wellbore trajectory, and the maximum drilling pressure of the drilled formation, the formation anisotropy index can be calculated in reverse.

[0073] Thus, after the anisotropy index of the formation is calculated, the process proceeds to step S140.

[0074] Step S140: Based on the formation anisotropy index calculated in step S130, calculate the formation build-up force of the formation to be drilled under different drilling pressures, and based on the above-mentioned pre-bent BHA three-dimensional mechanical model, calculate the drill bit anti-deviation force of the formation to be drilled under different drilling pressures, and select a reasonable drilling pressure based on the formation build-up force and drill bit anti-deviation force of the formation to be drilled under different drilling pressures.

[0075] In step S140, firstly, based on the formation anisotropy index obtained in step S130, it is necessary to calculate the formation build-up force of the formation to be drilled under different drilling pressures.

[0076] In one embodiment, based on the current formation anisotropy index, the dip angle of the formation to be drilled, the well inclination angle of the well section to be drilled, and the specified drilling pressure, the formation build-up force under different specified drilling pressure conditions is calculated using the build-up force calculation formula. Specifically, multiple alternative drilling pressure data are first allocated, and the currently calculated formation anisotropy index, alternative drilling pressure, well inclination angle of the well section to be drilled, and formation dip angle of the formation to be drilled are substituted into the above expression (11) to directly calculate the formation build-up force under different alternative drilling pressure data conditions.

[0077] Then, based on the well inclination angle of the section to be drilled and at least one alternative drilling pressure data, the drill bit anti-inclination force of the formation to be drilled under the specified alternative drilling pressure conditions is calculated.

[0078] Specifically, multiple alternative drilling pressure data are first allocated, and then the well inclination angle of the section to be drilled and the mechanical parameters of the drill string under the specified alternative drilling pressure are determined by combining the basic parameters. Then, based on the current well inclination angle, the mechanical parameters of the drill string under the specified alternative drilling pressure and the basic parameters, the pre-bent BHA three-dimensional mechanical model is used to calculate the lateral force of the drill bit under any tool face angle under the current alternative drilling pressure by using expressions (1)-(6). Furthermore, the anti-deviation force of the drill bit and the corresponding anti-deviation force direction are calculated under the current alternative drilling pressure by using expressions (7)-(10).

[0079] Therefore, by configuring different alternative drilling pressure data, the drill bit anti-deviation force and the corresponding anti-deviation force direction can be obtained under different alternative drilling pressure conditions.

[0080] For example: determine the corresponding pre-bending BHA anti-swerving force F when the drilling pressure is 60kN, 80kN, 100kN, 120kN, 140kN, 160kN, 180kN, 200kN, etc. s and the strata orogenic force F m .

[0081] Finally, step S140 will also select a reasonable drilling pressure based on the formation deflection force and drill bit anti-deflection force of the formation to be drilled under different alternative drilling pressure data conditions.

[0082] Specifically, firstly, based on the formation deflection force and drill bit anti-deflection force of the formation to be drilled under different drilling pressures, the effective anti-deflection force of the formation to be drilled under different drilling pressures is calculated.

[0083] In one embodiment, the effective anti-deviation force under the corresponding drilling pressure is obtained by calculating the difference between the drill bit anti-deviation force and the formation deflection force under the same drilling pressure.

[0084] Furthermore, the effective anti-deviation force under different (alternative) drill pressure conditions is calculated using the following expression:

[0085] F e =F s -F m =f(W) (12)

[0086] Among them, F e This indicates an effective anti-slant force.

[0087] Then, curve fitting was performed on the effective anti-deviation force of the formation under different drilling pressures to obtain the relationship curve between drilling pressure and effective anti-deviation force. See [link to relevant documentation]. Figure 5 and Figure 6 .

[0088] Finally, based on the currently plotted curve showing the relationship between drill pressure and effective anti-deviation force, a reasonable drill pressure is identified.

[0089] In one embodiment, the drilling pressure corresponding to zero effective anti-directional force is extracted from the relationship curve between drilling pressure and effective anti-directional force, and this drilling pressure is then used as the reasonable drilling pressure for the formation to be drilled. This is determined to be F. e The drilling pressure when = 0 is the applicable drilling pressure for the pre-bending dynamic anti-deviation and fast bottom drilling tool assembly.

[0090] Example 2

[0091] Taking a well numbered 81X as an example, section A in this well is selected as the section to be drilled, and the reasonable drilling pressure determination method described in Example 1 is applied. The implementation process and effects of the reasonable drilling pressure determination method described in this embodiment of the invention are explained below.

[0092] (1) The structural parameters of the pre-bent bottom drill string assembly (pre-bent BHA) were measured using a laser measuring instrument and a special gauge; the structure of one pre-bent BHA used in well 81X is as follows:

[0093] 241.3mm PDC×0.46m+185 screw (H7LZ185×7.0-3DWGL-1.25°, with 236mm stabilizer)×7.63m+178 float valve×0.62m+168 connector (410×411)×0.74m+237mm stabilizer×1.64m+177.8mm non-magnetic drill collar×9.27m+177.8mm non-magnetic suspension×0.97m+177.8mm drill collar×122.64m+177.8mm drilling shock device×5.47m+177.8mm drill collar×18.74m+…

[0094] Structural parameters: L1 = 1.21m; L2 = 8.44m; L21 = 0.75m; Ds1 = 236mm; Ds2 = 237mm. See L1, L2, and L21 for details. Figure 3 As shown, Ds1 and Ds2 are the outer diameters of the two stabilizers, respectively.

[0095] (2) Measure wellbore trajectory parameters using a triaxial accelerometer, fluxgate sensor or MWD, single-point or multi-point inclinometer;

[0096] The well inclination angle at a depth of 5000m was measured to be 1.1°, the azimuth angle to be 57.2°, and the dogleg degree to be 0° / 30m.

[0097] (3) The maximum dip angle of the drilled strata was measured to be 6°, and the dip angle of the strata to be drilled does not exceed 6°.

[0098] (4) The anti-directional force of the drill bit at the maximum operating pressure in the drilled formation without increasing the directional angle is 10.36 kN. The calculation results are shown in [reference]. Figure 4 ;

[0099] (5) Make the formation anti-inclination force equal to 10.36kN, which means that the formation comprehensive anisotropy index is 0.6541 when the wellbore does not increase in inclination.

[0100] (6) When the drilling pressure is determined to be 60kN, 80kN, 100kN, 120kN, 140kN, 160kN, 180kN, 200kN, 220kN and 240kN, the anti-swerving force of the pre-bent BHA is 10.25kN, 10.35kN, 10.37kN, 10.31kN, 10.46kN, 10.46kN, 10.44kN, 10.50kN, 10.54kN and 10.33kN respectively;

[0101] (7) The build-up forces of the formation to be drilled under the above drilling pressures are determined to be 4.14 kN, 5.52 kN, 6.91 kN, 8.29 kN, 9.67 kN, 11.06 kN, 12.43 kN, 13.81 kN, 15.19 kN, and 15.57 kN, respectively. Combining with step (6), the effective anti-deviation forces of the pre-bending BHA corresponding to different drilling pressures are obtained as follows: 6.11 kN, 4.82 kN, 3.46 kN, 2.02 kN, 0.79 kN, -0.59 kN, -1.99 kN, -3.31 kN, -4.65 kN, and -6.24 kN, respectively. Figure 5 The fitting results of the relationship curve between drilling pressure and effective anti-deviation force in Example 2 are shown. The variation law of effective anti-deviation force with drilling pressure is: Fe=-0.0681W+10.2605.

[0102] (8) Let Fe = 0, the applicable drilling pressure of the pre-bending dynamic anti-slant drilling fast bottom drill assembly is 150.73kN, and 150kN is often used in actual operation.

[0103] Example 3

[0104] Taking a well numbered 81X as an example, section B in this well is selected as the section to be drilled, and the reasonable drilling pressure determination method described in Example 1 is applied. The implementation process and effects of the reasonable drilling pressure determination method described in this embodiment of the invention are explained below.

[0105] (1) Measure the structural parameters of the pre-bent bottom drill assembly (pre-bent BHA) using a laser measuring instrument and special gauges;

[0106] The pre-bent BHA structure used in the Shunbei 81X well is as follows:

[0107] 241.3mm PDC×0.46m+185 screw (H7LZ185×7.0-3DWGL-1.25°, with 236mm stabilizer)×7.63m+178 float valve×0.62m+168 connector (410×411)×0.74m+237mm stabilizer×1.64m+177.8mm non-magnetic drill collar×9.27m+177.8mm non-magnetic suspension×0.97m+177.8mm drill collar×122.64m+177.8mm drilling shock device×5.47m+177.8mm drill collar×18.74m+…

[0108] Structural parameters: L1 = 1.21m; L2 = 8.44m; L21 = 0.75m; Ds1 = 236mm; Ds2 = 237mm. See L1, L2, and L21 for details. Figure 3 As shown, Ds1 and Ds2 are the outer diameters of the two stabilizers, respectively. This BHA is the same as in Example 2.

[0109] (2) Measure wellbore trajectory parameters using a triaxial accelerometer, fluxgate sensor or MWD, single-point or multi-point inclinometer;

[0110] The well inclination angle at a depth of 5000m was measured to be 1.1°, the azimuth angle to be 57.2°, and the dogleg degree to be 0° / 30m.

[0111] (3) The maximum dip angle of the drilled strata was measured to be 6°, and the dip angle of the strata to be drilled was 10°.

[0112] (4) The anti-directional force of the drill bit at the maximum operating pressure in the drilled formation without increasing the directional angle is 10.36 kN. The calculation results are shown in [reference]. Figure 4 ;

[0113] (5) Make the formation anti-inclination force equal to 10.36kN, which means that the comprehensive formation anisotropy index is 0.6541 when the wellbore does not increase in inclination.

[0114] (6) When the drilling pressure is determined to be 60kN, 80kN, 100kN, 120kN, 140kN, 160kN, 180kN, 200kN, 220kN and 240kN, the anti-swerving force of the pre-bent BHA is 10.25kN, 10.35kN, 10.37kN, 10.31kN, 10.46kN, 10.46kN, 10.44kN, 10.50kN, 10.54kN and 10.33kN respectively;

[0115] (7) The build-up forces of the formation to be drilled under the above drilling pressure are determined to be 7.44kN, 9.92kN, 12.40kN, 14.89kN, 17.36kN, 19.85kN, 22.33kN, 24.81kN, 27.29kN, and 29.77kN, respectively. Combined with step (6), the effective anti-deviation forces of the pre-bent BHA under different drilling pressures are obtained to be 2.81kN, 0.43kN, -2.03kN, -4.57kN, -6.91kN, -9.39kN, -11.89kN, -14.31kN, -17.75kN, and -19.44kN, respectively. Figure 6 The fitting results of the relationship curve between drilling pressure and effective anti-deviation force in Example 3 are shown. The variation law of effective anti-deviation force with drilling pressure is: Fe=-0.1231W+10.2605.

[0116] (8) Let Fe = 0, the applicable drilling pressure of the pre-bending dynamic anti-slant drilling fast bottom drill assembly is 83.35 kN, and 80 kN is often used in actual operation.

[0117] Example 4

[0118] Based on the reasonable drill pressure determination method described in Embodiments 1 to 3 above, this invention also provides a system for determining the reasonable drill pressure for pre-bent BHAs (also referred to as a "reasonable drill pressure determination system"). This reasonable drill pressure determination system is used to implement the above-described reasonable drill pressure determination method.

[0119] Figure 7 This is a schematic diagram of a system for determining the appropriate drilling pressure for a pre-bent BHA, according to an embodiment of this application. Figure 7 As shown, the reasonable drilling pressure determination system described in this embodiment of the invention includes: a measuring device 71, a drill bit anti-deviation force calculation module 72 for drilled formations, a formation anisotropy index generation module 73, and a drilling pressure optimization module 74.

[0120] Specifically, the measuring device 71 is implemented according to the method described in step S110 above, and is configured to measure basic parameters, including wellbore trajectory parameters, drill string structure parameters, and formation dip angle parameters; the drill bit anti-deviation force calculation module 72 for drilled formations is implemented according to the method described in step S120 above, and is configured to calculate the drill bit anti-deviation force under maximum drilling pressure in the drilled formation based on the basic parameters and using the pre-bent BHA three-dimensional mechanical model; the formation anisotropy index generation module 73 is implemented according to the method described in step S130 above, and is configured to use the drill bit anti-deviation force under maximum drilling pressure as the deflection force of the drilled formation, and based on this, inversely calculate the formation anisotropy index; the drilling pressure optimization module 74 is implemented according to the method described in step S140 above, and is configured to calculate the deflection force of the formation to be drilled under different drilling pressures based on the formation anisotropy index, and calculate the drill bit anti-deviation force of the formation to be drilled under different drilling pressures based on the pre-bent BHA three-dimensional mechanical model, and based on this, optimize a reasonable drilling pressure.

[0121] This invention discloses a method and system for determining the appropriate drilling pressure (DP) for a pre-bent borehole stabilizer (BHA). Based on measured wellbore trajectory parameters, drill string structure parameters, and formation dip angle, the method and system invert the anisotropy index of the formation using the drilled formation dip angle, well inclination angle, and the anti-deviation force of the pre-bent BHA. Subsequently, the effective anti-deviation force of the pre-bent BHA in the formation to be drilled under different DPs is determined. Finally, the maximum DP when the effective anti-deviation force is greater than zero is determined and used as the applicable DP for the pre-bent dynamic anti-deviation fast bottom drilling tool assembly. This invention selects the DP by considering the effective anti-deviation force of the pre-bent BHA, reasonably inferring the appropriate DP. It considers both the anti-deviation force of the pre-bent BHA and the formation build-up force, making it simple, easy to implement, and low-cost, suitable for widespread use, unlike existing technologies that mainly rely on trial and error to determine the appropriate DP, which lacks evaluation criteria once the formation changes. Secondly, this invention is applicable to all dual-stabilizer pre-bent BHAs with bend angles between 0.75 and 1.5°. Furthermore, this invention is applicable to situations where the maximum well inclination angle is less than 4°.

[0122] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

[0123] In the description of this invention, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," "outer," "front end," "rear end," "head," "tail," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0124] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0125] It should be understood that the embodiments disclosed herein are not limited to the specific structures, processing steps, or materials disclosed herein, but should be extended to equivalent substitutions of these features as understood by those skilled in the art. It should also be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting.

[0126] The phrase "an embodiment" or "an embodiment" used in this specification means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. Therefore, the phrase "an embodiment" or "an embodiment" appearing in various places throughout the specification does not necessarily refer to the same embodiment.

[0127] While the embodiments disclosed in this invention are as described above, the content is merely for the purpose of facilitating understanding of the invention and is not intended to limit the invention. Any person skilled in the art to which this invention pertains may make any modifications and changes in form and detail of the implementation without departing from the spirit and scope disclosed herein; however, the scope of patent protection of this invention shall still be determined by the scope defined in the appended claims.

Claims

1. A method for determining the appropriate drilling pressure for pre-bent BHAs, characterized in that, include: Measure basic parameters, including wellbore trajectory parameters, drill string structure parameters, and formation dip angle parameters; Based on the basic parameters, the anti-deviation force of the drill bit under the maximum drilling pressure in the drilled formation is calculated using the three-dimensional mechanical model of pre-bent BHA. The drill bit anti-directional force under the maximum drilling pressure is used as the directional force of the drilled formation, and based on this, the formation anisotropy index is inverted. Based on the formation anisotropy index, the drilling force of the formation under different drilling pressures is calculated, and based on the pre-bent BHA three-dimensional mechanical model, the anti-deviation force of the drill bit under different drilling pressures is calculated, and based on this, a reasonable drilling pressure is selected.

2. The method according to claim 1, characterized in that, The wellbore trajectory parameters include the well depth and the inclination angle, azimuth angle and dogleg degree at the corresponding well depth; The drill string structural parameters include the bend angle and position of the screw or pre-bent short joint, as well as the outer diameter, inner diameter, length and density of the drill string, which includes a drill bit, drill collar, stabilizer and adapter. The formation dip angle parameters include the dip angle of the drilled formation and the dip angle of the formation to be drilled.

3. The method according to claim 2, characterized in that, Based on the basic parameters, the anti-directional force of the drill bit under a specified drilling pressure is calculated using the three-dimensional mechanical model of pre-bent BHA, including: Based on the basic parameters, determine the drill string mechanical parameters under the current well inclination angle and specified drilling pressure. The drill string mechanical parameters include the axial pressure at the bottom of the drill string and the contact pressure between the stabilizer and the well wall. Based on the current well inclination angle, drill string mechanical parameters and basic parameters under a specified drilling pressure, the lateral force of the drill bit under any tool face angle is calculated using the pre-bent BHA three-dimensional mechanical model. Calculate the combined directional force and the combined azimuth force based on the lateral force of the drill bit under any tool face angle. Based on the combined inclination force and the combined azimuth force, calculate the drill bit anti-inclination force and its direction.

4. The method according to claim 3, characterized in that, Calculate the anti-deviation force of the drill bit in the drilled formation based on the maximum drilling pressure when the drill bit does not increase the directional deviation in the drilled formation; Based on the well inclination angle of the section to be drilled and at least one alternative drilling pressure data, calculate the drill bit anti-inclination force of the formation to be drilled under the specified alternative drilling pressure conditions.

5. The method according to claim 3 or 4, characterized in that, The three-dimensional mechanical model of the pre-bent BHA is represented by the following expression: Among them, f a f t represents the friction coefficients in the axial and tangential directions, respectively; x represents the coordinate along the drill string axis, with the bottom end of the i-th drill string as the starting point; E i I represents the elastic modulus of the i-th drill string segment; i u represents the moment of inertia of the i-th segment of the drill string; i v represents the deflection of the i-th drill string along the y-direction; i M represents the deflection of the i-th drill string along the z-direction; ti q represents the torque experienced by the i-th segment of the drill string; i α represents the weight per unit length of the i-th drill string segment in the drilling fluid; i B represents the well inclination angle of the well section containing the i-th drill string segment; i L represents the axial pressure at the bottom of the i-th drill string segment; i N represents the length of the i-th drill string segment; i D represents the contact pressure between the lower end of the i-th drill string and the wellbore; w Indicates the wellbore diameter; The lateral force of the drill bit is calculated using the following expression: Where ω represents the tool face angle, F α(ω) , These represent the lateral forces of the drill bit in different directions under the tool face angle ω.

6. The method according to any one of claims 3 to 5, characterized in that, The following expressions are used to calculate the combined inclination force, combined azimuth force, drill bit anti-inclination force, and direction of the anti-inclination force: Among them, F sα Indicates the combined oblique force. F represents the resultant azimuth force. s α represents the anti-skew force of the drill bit. s The direction of the anti-swerving force is indicated by , and n represents the total number of calculation points obtained by dividing one revolution of the drill bit into equal parts.

7. The method according to any one of claims 1 to 6, characterized in that, The step of using the drill bit anti-directional force under the maximum drilling pressure as the directional force of the drilled formation, and inverting the formation anisotropy index based on this, includes: Establish a formula for calculating the formation buildup force that characterizes the relationship between formation buildup force, drilling pressure, formation anisotropy index, and formation dip angle; Based on the drill bit anti-directional force under maximum drilling pressure, the dip angle of the drilled formation, and the maximum drilling pressure of the drilled formation, the anisotropy index of the current formation is obtained using the aforementioned formula for calculating the directional force. The step of calculating the drilling force of the formation under different drilling pressures based on the formation anisotropy index includes: Based on the current formation anisotropy index, the dip angle of the formation to be drilled, and the specified drilling pressure, the formation build-up force under different specified drilling pressure conditions is calculated using the aforementioned build-up force calculation formula.

8. The method according to claim 7, characterized in that, The formula for calculating the inclined force is expressed by the following expression: Among them, F m denoted by , W represents the drilling pressure, h represents the formation anisotropy index, c = π / 180, β represents the formation dip angle, and α represents the well inclination angle.

9. The method according to any one of claims 1 to 8, characterized in that, Based on the formation inclination force and drill bit anti-inclination force of the formation to be drilled under different drilling pressures, the optimal drilling pressure is selected, including: Calculate the effective anti-deviation force of the formation to be drilled under different drilling pressures based on the formation deflection force and drill bit anti-deviation force of the formation to be drilled under different drilling pressures. Curve fitting was performed on the effective anti-deviation force of the formation to be drilled under different drilling pressures to obtain the relationship curve between drilling pressure and effective anti-deviation force. Based on the relationship curve between drilling pressure and effective anti-deviation force, a reasonable drilling pressure is identified. Specifically, the drilling pressure corresponding to the effective anti-deviation force being zero is extracted from the relationship curve, thereby obtaining the reasonable drilling pressure for the formation to be drilled.

10. The method according to claim 9, characterized in that, The effective anti-deviation force under the corresponding drilling pressure is obtained by calculating the difference between the drill bit anti-deviation force and the formation deflection force under the same drilling pressure.

11. A system for determining the appropriate drilling pressure for a pre-bent BHA, characterized in that, The system is used to implement the method as described in any one of claims 1 to 10, wherein the system comprises: A measuring device configured to measure basic parameters, including wellbore trajectory parameters, drill string structure parameters, and formation dip angle parameters; The drill bit anti-deviation force calculation module for drilled formations is configured to calculate the drill bit anti-deviation force under the maximum drilling pressure in drilled formations based on basic parameters and using the pre-bent BHA three-dimensional mechanical model. The formation anisotropy index generation module is configured to use the drill bit anti-directional force under the maximum drilling pressure as the directional force of the drilled formation, and based on this, to invert the formation anisotropy index. The drilling pressure optimization module is configured to calculate the directional force of the formation to be drilled under different drilling pressures based on the formation anisotropy index, and to calculate the anti-directional force of the drill bit under different drilling pressures based on the pre-bent BHA three-dimensional mechanical model, and to optimize a reasonable drilling pressure accordingly.

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