Floating length optimization method, system and equipment

Abstract

The invention belongs to the field of well drilling, particularly relates to a floating length optimization method, system and equipment, and aims to solve the problems that in the prior art, the precision of the selected floating length is poor, and an air section is difficult to descend. The method comprises the steps that well site data in the process from drifting to drilling to bottom are obtained and screened, the position of a drill bit and the optimal solution of hook load are calculated after screening, and data obtained through calculation serve as input data; based on the input data, a drifting friction coefficient is obtained through a pre-constructed rigid rod model; the drifting pipe inner friction resistance coefficient and the drifting pipe outer friction resistance coefficient are added to the safety value, and then the lower casing pipe inner friction resistance coefficient and the lower casing pipe outer friction resistance coefficient are obtained; and the optimal floating length is obtained through a pre-constructed floating length optimization equation in combination with the inner friction resistance coefficient of the lower casing and the outer friction resistance coefficient of the lower casing. According to the invention, the precision of floating length selection is improved, and the problem that the air section is difficult to enter is solved.

Description

Background Art

[0002] In recent years, the floating casing running technology has been widely applied in the domestic shale gas market and extended-reach horizontal wells in various oilfields. It uses a floating collar as a "temporary barrier" in the pipe string. After the casing reaches the bottom, the floating collar is opened by applying pressure at the wellhead, enabling the efficient and safe running of the pipe string. Currently, in floating casing running operations, the floating length is mainly predicted by software simulation, and the maximum hook load value at the wellhead when the casing reaches the bottom is selected as the means to determine the floating length. However, in actual applications, the selected friction coefficient is mostly an empirical value, which does not match the on-site situation. Selecting the maximum hook load value at the wellhead when the casing reaches the bottom as the floating length requires using a back-up tong when the self-weight of the floating section of the casing is insufficient for making up the threads, so there is a problem that an overly long floating length affects the running efficiency. At the same time, in some extended-reach horizontal wells, there is a phenomenon that it is difficult to run the air section when selecting the maximum hook load value at the wellhead when the casing reaches the bottom as the floating length. Summary of the Invention

[0003] To solve the above problems in the prior art, that is, the poor accuracy of the selected floating length and the difficulty in running the air section in the prior art, in the first aspect of the present invention, a method for optimizing the floating length is provided, which is used to calculate the optimal floating length of the floating collar in floating casing running operations, including:

[0004] Step S10: Obtain the wellsite data from the start of hole cleaning to the bottom of the drill and perform screening. After screening, calculate the optimal solutions of the bit position and hook load, and use the calculated data as input data; the wellsite data includes bit position, hook load, rotary speed, pump pressure, displacement, traveling block height, and torque data.

[0005] Step S20: Based on the input data, obtain the hole cleaning friction coefficient through a pre-constructed rigid rod model; the hole cleaning friction coefficient includes the internal friction coefficient of the hole cleaning pipe and the external friction coefficient of the hole cleaning pipe.

[0006] Step S30: Add the internal friction coefficient of the hole cleaning pipe and the external friction coefficient of the hole cleaning pipe to the safety values respectively to obtain the internal friction coefficient of the casing running pipe and the external friction coefficient of the casing running pipe.

[0007] Step S40: Combine the internal friction coefficient of the casing running pipe and the external friction coefficient of the casing running pipe, and obtain the optimal floating length through a pre-constructed floating length optimization equation.

[0008] In some preferred embodiments, the method for obtaining the wellsite data from the start of hole cleaning to the bottom of the drill and performing screening, and calculating the optimal solutions of the bit position and hook load after screening is as follows:

[0009] Screen out the data of the bit position, hook load, and traveling block height corresponding to non-zero values of the rotary speed, pump pressure, displacement, and torque. Group the selected data according to the time sequence and the traveling block height. Each group of data corresponds to the process of a casing from being connected to the pipe string to being lowered to the wellhead. Numerically optimize the bit position and hook load for each group after screening. The optimization formula is:

[0010]

[0011] where M is the optimized bit position; m i is the well depth at a certain moment when the casing in the group is lowered; H is the optimized hook load; h i is the hook load at the wellhead corresponding to the bit position m i in the group; n is the number of data in the group.

[0012] In some preferred embodiments, the rigid rod model is:

[0013]

[0014] where K d is the wellbore curvature, C k is the conversion coefficient, Δα is the change in well inclination angle, is the azimuth change rate, K α is the well inclination angle change rate, E is the elastic modulus of the pipe string, I is the moment of inertia of the pipe string, K is the wellbore curvature, τ is the wellbore tortuosity, F t2 represents the axial force at the upper end of the selected pipe string element, F t1 represents the axial force at the lower end of the selected pipe string element, q m represents the self-weight per unit length of the casing, K f represents the buoyancy coefficient, r m represents the drilling fluid density, r s represents the density of the casing string material, α represents the well inclination angle, Δs represents the element length, μ represents the friction coefficient, i.e., the frictional resistance coefficient, N represents the contact pressure between the pipe string and the wellbore wall, ΔK represents the change in wellbore curvature between the upper and lower ends of the element segment, N n represents the uniform contact pressure in the principal normal direction, N b represents the uniform contact pressure in the binormal direction, M b represents the moment in the binormal direction, s represents the selected element length.

[0015] In some preferred embodiments, the preferred equation for the floating length is:

[0016]

[0017] where F xThe sum of the hook loads at the start of lowering to the bottom of the well is \(F\), the measured depth at the bottom of the well is \(z\), the optimal floating length is \(x\), the floating length when the floating collar is placed at the critical resistance angle is \(y\), the function \(f\) is the friction resistance calculation model, i.e., the rigid rod model, \(n\) is the correction value, \(\eta\) is the optimal solution, and when solving for the maximum \(\eta\), \(x\) is the optimal floating length.

[0018] In some preferred embodiments, the friction coefficient inside the reaming pipe and the friction coefficient outside the reaming pipe are respectively added to a safety value, and the method is as follows:

[0019] The friction coefficient inside the reaming pipe and the friction coefficient outside the reaming pipe are respectively added to the safety value to obtain the friction coefficient inside the casing string and the friction coefficient outside the casing string; wherein, the calculation method of the safety value is:

[0020] \(\sigma=\max(|\mu min -\mu|,|\mu - \mu max |)\times150\%\)

[0021] wherein, \(\sigma\) is the safety value, which is 1.5 times the absolute difference among \(\mu min \), \(\mu\), and \(\mu max ; \(\mu\) is the friction coefficient outside the reaming pipe obtained by calculating the optimal solution of the bit position and the hook load through the rigid rod model; \(\mu min is the minimum friction coefficient outside the reaming pipe calculated by using only the unoptimized data; \(\mu max is the maximum friction coefficient outside the reaming pipe calculated by using only the unoptimized data.

[0022] In some preferred embodiments, after step S40, step S50 is further included.

[0023] According to the optimal floating length, through the rigid rod model, calculate the hook load at the wellhead when the entire casing string reaches the optimal floating length. If the hook load is equal to 0, the non-top drive drilling rig equipment adopts the method of connecting the floating collar in advance to avoid the situation of difficult entry of the air section, and the top drive drilling rig equipment adopts the method of top drive downward pressure to increase the axial downward pressure of the pipe string to achieve the expected optimal floating length; wherein, the method of connecting the floating collar in advance is to connect the floating collar when the hook load at the wellhead is a set kN.

[0024] In the second aspect of the present invention, a floating length optimization system is proposed, which is used to calculate the optimal floating length of the floating collar in the floating casing operation. The system includes:

[0025] A data screening module, configured to obtain the wellsite data from the start of reaming to the bottom of the drill and perform screening. After screening, calculate the optimal solution of the bit position and the hook load, and use the calculated data as input data; the wellsite data includes the bit position, the hook load, the rotation speed, the pump pressure, the displacement, the traveling block height, and the torque data.

[0026] The friction coefficient calculation module is configured to obtain the wellbore cleaning friction coefficient based on the input data through a pre-constructed rigid rod model; the wellbore cleaning friction coefficient includes the friction coefficient inside the wellbore cleaning pipe and the friction coefficient outside the wellbore cleaning pipe;

[0027] The coefficient weighting module is configured to add the friction coefficient inside the wellbore cleaning pipe and the friction coefficient outside the wellbore cleaning pipe to a safety value respectively to obtain the friction coefficient inside the casing string and the friction coefficient outside the casing string;

[0028] The floating length acquisition module is configured to obtain the optimal floating length through a pre-constructed floating length optimization equation in combination with the friction coefficient inside the casing string and the friction coefficient outside the casing string.

[0029] In a third aspect of the present invention, a floating length optimization device is proposed, including:

[0030] At least one processor; and a memory communicatively connected to at least one of the processors; wherein, the memory stores instructions executable by the processor, and the instructions are used to be executed by the processor to implement the above-mentioned floating length optimization method.

[0031] In a fourth aspect of the present invention, a computer-readable storage medium is proposed, and the computer-readable storage medium stores computer instructions, and the computer instructions are used to be executed by the computer to implement the above-mentioned floating length optimization method.

[0032] Advantages of the present invention:

[0033] The present invention improves the accuracy of floating length selection and solves the problem that it is difficult to lower the air section.

[0034] 1) The method of the present invention screens the well site data, and the screened data can have a smaller variance value with the curve calculated by the pipe string mechanics equation, and is more easily coupled;

[0035] 2) The friction coefficient of the casing string with an additional safety value in the present invention can better approximate the actual construction situation on site, providing clear guidance for the prediction of the hook load during casing string lowering;

[0036] 3) The present invention uses the optimal floating length calculated according to the floating length optimization equation, and can place the floating collar below the critical resistance angle without significantly reducing the bottom hole hook load, thereby increasing the hook load during the lowering process;

[0037] 4) The present invention checks whether the minimum value of the ungrouted air section lowering is greater than zero. If a negative value appears, in actual construction, methods such as connecting the floating collar in advance or using the top drive to press down to increase the axial downward pressure of the pipe string are adopted to lower it, solving the problem that it is difficult to lower the air section. Description of the Drawings

[0038] Other features, objectives, and advantages of the present application will become more apparent by reading the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0039] Figure 1 is a schematic flowchart of a preferred method for floating length in an embodiment of the present invention;

[0040] Figure 2 is a schematic framework flowchart of a preferred system for floating length in an embodiment of the present invention;

[0041] Figure 3 is a schematic simplified flowchart of a preferred method for floating length in an embodiment of the present invention;

[0042] Figure 4 is a schematic diagram of the force analysis of the casing in an embodiment of the present invention. Detailed Embodiments

[0043] The present application will be further described in detail below with reference to the accompanying drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the related invention and are not intended to limit the invention. Additionally, it should be noted that for the sake of convenience of description, only parts related to the relevant invention are shown in the drawings.

[0044] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The present application will be described in detail below with reference to the drawings and embodiments.

[0045] A preferred method for floating length of the present invention is used to calculate the optimal floating length of the floating collar during the operation of floating the casing, as Figure 1 shown, and includes:

[0046] Step S10: Obtain the wellsite data from the start of hole cleaning to the bottom of the drill string and perform screening. After screening, calculate the optimal solutions of the bit position and hook load, and use the calculated data as input data; the wellsite data includes bit position, hook load, rotary speed, pump pressure, displacement, traveling block height, and torque data;

[0047] Step S20: Based on the input data, obtain the hole cleaning friction coefficient through a pre-constructed rigid rod model; the hole cleaning friction coefficient includes the internal friction coefficient of the hole cleaning pipe and the external friction coefficient of the hole cleaning pipe;

[0048] Step S30: Add the internal friction coefficient of the hole cleaning pipe and the external friction coefficient of the hole cleaning pipe to the safety values respectively to obtain the internal friction coefficient of the casing string during running and the external friction coefficient of the casing string during running;

[0049] Step S40: Combine the internal friction coefficient of the casing string and the external friction coefficient of the casing string, and obtain the optimal floating length through a pre-established floating length optimization equation.

[0050] To more clearly illustrate the floating length optimization method of the present invention, the following will Figure 3 detail each step in the method embodiment of the present invention.

[0051] In the operation of floating the casing string in the present invention, first, according to the data of the wellsite data remote transmission system, the well depth and the corresponding hook load data during the hole cleaning process are screened out; secondly, they are substituted into the string mechanics equation (i.e., the rigid rod model) to calculate the hole cleaning friction coefficient, and then a certain safety value is added as the casing string friction coefficient; then, the optimal floating length is calculated according to the floating length optimization equation, and finally, the hook load condition of the optimal floating length is checked again. The casing string friction coefficient calculated by adding a safety value after calculating through the screened hook load data can better approximate the on-site construction situation, providing clear guidance for the prediction of the casing string hook load; using the optimal floating length calculated according to the floating length optimization equation, the floating collar can be placed below the critical resistance angle without significantly reducing the bottom hole hook load, improving the hook load during the lowering process; checking the hook load condition of the optimal floating length mainly checks whether the minimum value of the air section without grouting during lowering is greater than zero. If a negative value appears, it is recommended to use methods such as connecting the floating collar in advance or pressing down with the top drive to increase the axial downward pressure of the string during actual construction. Specifically as follows:

[0052] Step S10: Obtain the wellsite data from the start of hole cleaning to the bottom of the drill string and perform screening. After screening, calculate the optimal solutions of the bit position and the hook load, and use the calculated data as input data; the wellsite data includes bit position, hook load, rotation speed, pump pressure, displacement, traveling block height, and torque data.

[0053] In this embodiment, after the hole cleaning reaches the bottom, through the wellsite data remote transmission system, select the bit position, hook load, rotation speed, pump pressure, displacement, traveling block height, and torque data from the start of hole cleaning to the bottom of the drill string, and group them in chronological order; screen the data, and screen out the data of the bit position, hook load, and traveling block height corresponding to non-zero rotation speed, pump pressure, displacement, and torque; after screening, calculate the optimal solutions of the bit position and the hook load, and use the calculated data as input data. At this time, the bit position and the corresponding hook load are used as hole cleaning data, and each group of data corresponds to the process of a casing string from being connected to the string to being lowered to the wellhead. Numerically optimize the bit position and hook load of each group after screening. The optimization formula is:

[0054]

[0055] where M is the optimized bit position, m; m iis the well depth at a certain moment when the casing in the group is lowered, m; H is the optimized hook load, kN (the optimized hook load, together with the corresponding well depth, is brought into the rigid rod model to calculate the friction coefficient μ, and H corresponds to the F of the topmost microelement of the entire pipe string in the rigid rod model t2 ); h i is the corresponding bit position in the group, m i is the hook load at the wellhead when m

[0056] Then substitute it into the pipe string mechanics equation (i.e., the rigid rod model described below) to calculate the open hole friction coefficient.

[0057] The data screened by the present invention can have a smaller variance value with the curve calculated by the pipe string mechanics equation and is more easily coupled; this is because the pipe string is not always in a state of force balance and the hook load is in a range of variation values. Considering that the driller's operation of lowering the pipe string during the actual lowering process of the pipe string is "acceleration - constant speed - deceleration", it is necessary to calculate the optimized solution of the hook load during the lowering process, considering the influence brought by the extreme value. The optimized solution is a given value and is more easily coupled.

[0058] Step S20, based on the input data, obtain the open hole friction coefficient through a pre - constructed rigid rod model; the open hole friction coefficient includes the friction coefficient inside the open hole pipe and the friction coefficient outside the open hole pipe.

[0059] In this embodiment, a force analysis of the pipe string is carried out, as Figure 4 shown. Considering the "rigidity" during the pipe string lowering process, a "rigid rod model" is established by considering the sectional bending moment and shear force. This model is based on the following assumptions: ① The pipe string is in linear elastic deformation; ② The pipe string is in continuous contact with the wellbore and their axes are consistent; ③ The wellbore is rigid; ④ The force on the pipe string is in a uniform state; ⑤ The cross - section of the pipe string is circular or annular, etc. The calculation equation obtained using the rigid rod model is:

[0060]

[0061] Among them, K d is the wellbore curvature, ° / 30m; C k is the conversion coefficient, dimensionless. When K d is in the unit of ° / 30m, C k takes 30; Δα is the change in well deviation angle, rad / m; is the azimuth change rate, rad / m; K α is the well deviation angle change rate, rad / m; E is the elastic modulus of the pipe string, N / m2; I is the moment of inertia of the pipe string, m4; K is the wellbore curvature, rad / m; τ is the wellbore torsion, rad / m, F t2 represents the axial force at the upper end of the selected pipe string microelement, N; F t1Denote the axial force at the lower end of the selected pipe string element, N; q m Denote the self-weight per unit length of the casing, N / m; K f Denote the buoyancy coefficient, dimensionless; r m Denote the density of the drilling fluid, kg / m 3 ; r s Denote the density of the casing string material, kg / m 3 ; α denotes the well deviation angle, rad; Δs denotes the element length, m; μ denotes the friction coefficient (i.e., the frictional resistance coefficient, which affects the hook load calculated by the rigid dry model. For an actual well, most of its values in the model are fixed, and the only variable is the friction coefficient. The external and internal friction coefficients of the pipe are both calculated using formula (2). However, when calculating the internal friction coefficient of the pipe, the selected data are the well depth of the casing and the corresponding hook load, because formula (2) calculates the hook load at the top of the pipe string using the Newton iteration method for each small element. When calculating the external friction coefficient of the pipe, calculate the well depth and hook load of the open hole section. When calculating into the casing, only need to iterate the previous results in), dimensionless; N denotes the contact pressure between the pipe string and the wellbore, N; ΔK denotes the change in wellbore curvature between the upper and lower ends of the element section, rad / m; N n Denote the uniformly distributed contact pressure in the principal normal direction, N; N b Denote the uniformly distributed contact pressure in the binormal direction, N; M b Denote the moment in the binormal direction, N / m, s denotes the selected element length, m. That is Figure 4 in respectively denote the binormal direction and the principal normal direction; Denote the tangent direction of the pipe string, q c Denote the uniformly distributed contact force of the element section.

[0062] Step S30, add the internal friction coefficient of the hole opener pipe and the external friction coefficient of the hole opener pipe to the safety value respectively to obtain the internal friction coefficient of the casing string and the external friction coefficient of the casing string;

[0063] In this embodiment, since the hole opener pipe string is a drill pipe, compared with the casing of the same opening sequence, its outer diameter is smaller and the contact area with the wellbore is much smaller. At the same time, the cross-sectional area of the casing is larger than that of the drill pipe, and the additional resistance brought by its rigidity is also larger. Therefore, the friction coefficient of the casing string needs to add a safety value on the basis of the friction coefficient of the hole opener.

[0064] The present invention adds the calculated internal friction coefficient of the hole opener pipe and the external friction coefficient of the hole opener pipe to the safety value respectively to obtain the internal friction coefficient of the casing string and the external friction coefficient of the casing string; among them, the calculation method of the safety value is:

[0065] σ = max(|μ min - μ|, |μ - μ max |) × 150% (3)

[0066] Among them, σ is the safety value and μ is min , μ, μ max 1.5 times the absolute difference between the three, dimensionless; μ is the external friction coefficient of the wellbore pipe calculated by the rigid rod model based on the optimized solution of the drill bit position and hook load, dimensionless; μ min is the minimum external friction coefficient of the wellbore pipe calculated using only screened but unoptimized data; μ max The maximum external friction coefficient of the wellbore calculated using only screened but unoptimized data.

[0067] Step S40, combining the inner friction coefficient of the lower casing and the outer friction coefficient of the lower casing, and obtaining the optimum floating length through a pre-constructed floating length optimization equation.

[0068] In this embodiment, in order to increase the hook load and the running efficiency during the running process, a coefficient can be added to place the floating collar below the critical resistance angle without significantly reducing the bottom hole hook load, thereby increasing the hook load during the running process. The preferred equation for the floating length is:

[0069]

[0070] Among them, F x is the sum of the hook loads from the time i = 30 m (i = 30, 60, ..., z) to the bottom of the well, kN; z is the bottom depth, m; x is the optimized floating length, m; y is the floating length when the floating coupling is placed at the critical resistance angle; function f is the friction calculation model, and this paper uses the previous rigid rod model; n is the correction value, and the difference between the bottom of the well hook load and the hook load at the critical resistance angle when the optimized floating length is satisfied cannot exceed n. For example, taking n as 3%, the hook load from the bottom of the well after the optimized floating length is 3% less than the maximum value, and the whole hook load is greater than 3%, which improves the running efficiency and reduces the occurrence of resistance during the running process, kN; η is the optimization solution, and x is the optimal floating length when η is the maximum.

[0071] After calculating the optimal floating length, it is necessary to check again, because the maximum hook load of the floating section is when the casing is lowered to the critical resistance angle. After exceeding it, the hook load will decrease. Check whether the minimum value of the ungrouted air section is greater than zero. If a negative value appears, it is recommended to increase the axial downward pressure of the pipe string by connecting the floating coupling in advance or pressing down the top drive in actual construction, as follows:

[0072] After step S40, step S50 is also included, in which the minimum value is verified for the air section that has not been grouted:

[0073] According to the optimal floating length, check whether the minimum value of the ungrouted air section lowered is less than zero. If so, the non-top drive drilling rig equipment adopts the method of pre-connected floating collar to avoid the situation of difficult lowering of the air section. The top drive drilling rig equipment adopts the method of top drive pressing down to increase the axial downward pressure of the pipe string to achieve the expected optimal floating length. That is, according to the optimal floating length, through the rigid rod model, calculate the hook load at the wellhead when the entire casing string reaches the optimal floating length. If the hook load is equal to 0, the non-top drive drilling rig equipment adopts the method of pre-connected floating collar to avoid the situation of difficult lowering of the air section. The top drive drilling rig equipment adopts the method of top drive pressing down to increase the axial downward pressure of the pipe string to achieve the expected optimal floating length; wherein, the method of pre-connected floating collar is to connect the floating collar when the hook load at the wellhead is a set kN (preferably 10 kN in the present invention).

[0074] The floating length optimization system of the second embodiment of the present invention is used to calculate the optimal floating length of the floating collar during the floating casing operation, as Figure 2 shown, the system includes:

[0075] The data screening module 100 is configured to obtain the wellsite data from the start of hole cleaning to the bottom of the drill and perform screening. After screening, calculate the optimal solutions of the bit position and hook load, and use the calculated data as input data; the wellsite data includes bit position, hook load, rotation speed, pump pressure, displacement, traveling block height, torque data;

[0076] The friction coefficient calculation module 200 is configured to obtain the hole cleaning friction coefficient based on the input data through a pre-constructed rigid rod model; the hole cleaning friction coefficient includes the internal friction coefficient of the hole cleaning pipe and the external friction coefficient of the hole cleaning pipe;

[0077] The coefficient weighting module 300 is configured to add the internal friction coefficient of the hole cleaning pipe and the external friction coefficient of the hole cleaning pipe to the safety value respectively to obtain the internal friction coefficient of the casing lowering pipe and the external friction coefficient of the casing lowering pipe;

[0078] The floating length obtaining module 400 is configured to obtain the optimal floating length through a pre-constructed floating length optimization equation in combination with the internal friction coefficient of the casing lowering pipe and the external friction coefficient of the casing lowering pipe.

[0079] Those skilled in the art can clearly understand that for the convenience and simplicity of description, the specific working process and related descriptions of the above-described system can refer to the corresponding process in the foregoing method embodiment and will not be repeated here.

[0080] It should be noted that the floating length optimization system provided in the above embodiments is only illustrated by the division of the above functional modules. In actual applications, the above functions can be allocated to different functional modules according to needs, that is, the modules or steps in the embodiments of the present invention can be further decomposed or combined. For example, the modules in the above embodiments can be combined into one module, or further split into multiple sub-modules to complete all or part of the functions described above. The names of the modules and steps involved in the embodiments of the present invention are only used to distinguish each module or step, and are not regarded as an improper limitation of the present invention.

[0081] A floating length optimization device according to the third embodiment of the present invention includes at least one processor; and a memory communicatively connected to at least one of the processors; wherein the memory stores instructions executable by the processor, and the instructions are used to be executed by the processor to implement the above-mentioned floating length optimization method.

[0082] A computer-readable storage medium according to the fourth embodiment of the present invention stores computer instructions, and the computer instructions are used to be executed by the computer to implement the above-mentioned floating length optimization method.

[0083] Those skilled in the art can clearly understand that for the convenience and brevity of description, the specific working processes and related descriptions of the above-described floating length optimization device and computer-readable storage medium can refer to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0084] Those skilled in the art should be able to realize that the modules and method steps of each example described in combination with the embodiments disclosed herein can be implemented by electronic hardware, computer software, or a combination of the two. The programs corresponding to the software modules and method steps can be placed in a random access memory (RAM), internal memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, removable disk, CD-ROM, or any other form of storage medium known in the art. To clearly illustrate the interchangeability of electronic hardware and software, the components and steps of each example have been generally described according to their functions in the above description. Whether these functions are executed in the form of electronic hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of the present invention.

[0085] The term "comprising" or any other similar term is intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus / device that comprises a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to those process, method, article, or apparatus / device.

[0086] So far, the technical solution of the present invention has been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easily understood by those skilled in the art that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the protection scope of the present invention.

Claims

1. A method for optimizing the floating length, which is used to calculate the optimal floating length of the floating collar during the floating casing operation, Characterized in that, This method includes the following steps: Step S10: Obtain the wellsite data from the start of hole cleaning to the bottom of the drill and perform screening. After screening, calculate the optimal solutions of the bit position and hook load, and use the calculated data as input data; the wellsite data includes the bit position, hook load, rotation speed, pump pressure, displacement, traveling block height, and torque data; Step S20: Based on the input data, obtain the hole cleaning friction coefficient through a pre-constructed rigid rod model; the hole cleaning friction coefficient includes the internal friction coefficient of the hole cleaning pipe and the external friction coefficient of the hole cleaning pipe; Step S30: Add the internal friction coefficient of the hole cleaning pipe and the external friction coefficient of the hole cleaning pipe to the safety value respectively to obtain the internal friction coefficient of the casing pipe and the external friction coefficient of the casing pipe; Step S40: Combine the internal friction coefficient of the casing pipe and the external friction coefficient of the casing pipe, and obtain the optimal floating length through a pre-constructed floating length optimization equation.

2. A method for optimizing the floating length according to claim 1, Characterized in that, The method for obtaining the wellsite data from the start of hole cleaning to the bottom of the drill and performing screening, and calculating the optimal solutions of the bit position and hook load after screening is as follows: Screen out the bit position, hook load, and traveling block height data corresponding to non-zero rotation speed, pump pressure, displacement, and torque. Group the selected data according to the time sequence and traveling block height. Each group of data corresponds to the process of a casing from being connected to the string to being lowered to the wellhead; perform numerical optimization on the bit position and hook load of each group after screening, and the optimization formula is: Among them, M is the optimized bit position; m i is the well depth when the casing in the group reaches a certain moment; H is the optimized hook load; h i is the hook load at the wellhead corresponding to the bit position m i in the group; n is the number of data in the group.

3. A method for optimizing the floating length according to claim 2, Characterized in that, The rigid rod model is: Among them, K d is the wellbore curvature, C k is the conversion coefficient, Δα is the change in well deviation angle, is the azimuth change rate, K α is the well deviation angle change rate, E is the elastic modulus of the pipe string, I is the moment of inertia of the pipe string, K is the wellbore curvature, τ is the wellbore torsion, F t2 represents the axial force at the upper end of the selected pipe string element, F t1 represents the axial force at the lower end of the selected pipe string element, q m represents the self-weight per unit length of the casing, K f represents the buoyancy coefficient, r m represents the density of the drilling fluid, r s represents the density of the casing string material, α represents the well deviation angle, Δs represents the element length, μ represents the friction coefficient, i.e., the friction resistance coefficient, N represents the contact pressure between the pipe string and the wellbore, ΔK represents the change in wellbore curvature between the upper and lower ends of the element section, N n represents the uniform contact pressure in the principal normal direction, N b represents the uniform contact pressure in the binormal direction, M b represents the moment in the binormal direction, s represents the selected element length.

4. A method for optimizing the floating length according to claim 3, Characterized in that, The floating length optimization equation is: Among them, F x is the sum of the hook loads when starting to lower to the bottom of the well, z is the measured depth at the bottom of the well, x is the optimal floating length, y is the floating length when the floating collar is placed at the critical resistance angle, the function f is the friction resistance calculation model, that is, the rigid rod model, n is the correction value, η is the optimal solution, and when solving for the maximum η, x is the optimal floating length.

5. A method for optimizing the floating length according to claim 1, Characterized in that, The method for adding the internal friction coefficient of the hole cleaning pipe and the external friction coefficient of the hole cleaning pipe to the safety value respectively is as follows: The internal friction coefficient of the hole cleaning pipe and the external friction coefficient of the hole cleaning pipe are added to the safety value respectively to obtain the internal friction coefficient of the casing pipe and the external friction coefficient of the casing pipe; among them, the calculation method of the safety value is: σ = max(|μ min - μ|, |μ - μ max |) × 150% where σ is the safety value, and is μ min , μ, μ max 1.5 times the absolute difference among the three; μ is the coefficient of external friction of the drift pipe calculated from the optimal solution of the bit position and the hook load through the rigid rod model; μ min is the minimum coefficient of external friction of the drift pipe calculated using only the unoptimized screened data; μ max is the maximum coefficient of external friction of the drift pipe calculated using only the unoptimized screened data.

6. A method for optimizing the floating length according to any one of claims 1-5, Characterized in that, After step S40, it further includes step S50, According to the optimal floating length, through the rigid rod model, calculate the hook load at the wellhead when the entire casing string reaches the optimal floating length. If the hook load is equal to 0, the non-top drive drilling rig equipment adopts the method of connecting the floating collar in advance to avoid the difficult situation of the air section being lowered. The top drive drilling rig equipment adopts the method of top drive pressing down to increase the axial downward pressure of the pipe string to achieve the expected optimal floating length; among them, the method of connecting the floating collar in advance is to connect the floating collar when the hook load at the wellhead is the set kN.

7. A floating length optimization system, which is used to calculate the optimal floating length of the floating collar during the floating casing operation, Characterized in that, This system includes: A data screening module, configured to obtain wellsite data during the process from well flushing start to drill bit reaching the bottom and perform screening, calculate the optimal solutions of the drill bit position and hook load after screening, and use the calculated data as input data; the wellsite data includes drill bit position, hook load, rotation speed, pump pressure, displacement, traveling block height, and torque data. A friction coefficient calculation module, configured to obtain the well flushing friction coefficient based on the input data through a pre-constructed rigid rod model; the well flushing friction coefficient includes the friction coefficient inside the well flushing pipe and the friction coefficient outside the well flushing pipe. A coefficient weighting module, configured to add the friction coefficient inside the well flushing pipe and the friction coefficient outside the well flushing pipe to a safety value respectively to obtain the friction coefficient inside the casing pipe and the friction coefficient outside the casing pipe. A floating length obtaining module, configured to obtain the optimal floating length through a pre-constructed floating length optimization equation in combination with the friction coefficient inside the casing pipe and the friction coefficient outside the casing pipe.

8. A floating length optimization device characterized in that it includes: at least one processor; and a memory communicatively connected to at least one of the processors; wherein, the memory stores instructions executable by the processor, and the instructions are used to be executed by the processor to implement a floating length optimization method according to any one of claims 1-6.

9. A computer-readable storage medium characterized in that the computer-readable storage medium stores computer instructions, and the computer instructions are used to be executed by the computer to implement a floating length optimization method according to any one of claims 1-6.

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