A directional sticking warning method and system based on drill string force analysis

Abstract

The present invention relates to the field of drilling technology, and particularly to a directional buckling warning method and system based on drill string force analysis. Determine the critical friction value according to a pre-constructed friction resistance statistical database; calculate the theoretical friction resistance of drilling according to the friction coefficient and the compensation deviation value; when the theoretical friction resistance is less than the critical friction resistance, normal construction is carried out; when the theoretical friction resistance is not less than the critical friction resistance, optimize the profile. If the theoretical friction resistance is less than the critical friction resistance after optimization, normal construction is carried out. If the theoretical friction resistance is still not less than the critical friction resistance after optimization, a warning is given. This method warns in advance of possible buckling phenomena, greatly improving the drilling speed during the drilling process and ensuring the wellbore quality.

Description

Technical Field

[0001] The present invention relates to the technical field of drilling, and particularly to a directional buckling warning method and system based on drill string force analysis. Background Art

[0002] Drilling is an important means for oil exploration and development. Directional drilling is an important branch of the drilling specialty, which is used to control the drill bit to drill along a pre-designed profile during the drilling process to improve the penetration rate of the target layer. During directional drilling, when the drill string is drilled downward, a large frictional force will gradually be generated between the drill string and the wellbore wall. Affected by the frictional force, the weight on bit cannot be transmitted to the drill bit in time, resulting in a series of problems. Especially during the construction of long horizontal sections, one of the problems that is likely to occur is the buckling problem. The directional buckling phenomenon seriously restricts the drilling speed and control accuracy.

[0003] The traditional method for dealing with directional buckling is to passively take corresponding treatment measures during the drilling process based on past experience or according to the buckling phenomenon that has occurred. Especially after the wellbore trajectory has been formed, not only is the effect limited, but it also affects the drilling cycle. Summary of the Invention

[0004] The purpose of the present invention is to provide a directional buckling warning method and system based on drill string force analysis for the defects of the existing technology, which can pre-warn of possible directional buckling phenomena before construction, effectively avoid the occurrence of directional buckling phenomena during construction, and save the construction cycle.

[0005] A directional buckling warning method based on drill string force analysis according to the present invention has the following technical solution:

[0006] Determine the critical friction value according to a pre-constructed friction resistance statistical database;

[0007] Calculate the theoretical friction resistance of the drilling according to the friction coefficient and the compensation deviation value;

[0008] When the theoretical friction resistance is less than the critical friction resistance, normal construction is carried out;

[0009] When the theoretical friction resistance is not less than the critical friction resistance, optimize the profile. If the theoretical friction resistance after optimization is less than the critical friction resistance, normal construction is carried out. If the theoretical friction resistance after optimization is still not less than the critical friction resistance, a warning is given.

[0010] Preferably, the friction resistance statistical database is obtained by statistical analysis of the friction resistance when buckling occurs during the directional process of the drilled wells in previous years.

[0011] Preferably, calculating the theoretical friction resistance of the drilling according to the friction coefficient and the compensation deviation value includes:

[0012] Based on the friction coefficient, calculate the initial theoretical friction value of the drilling operation;

[0013] Sum the initial theoretical friction value and the compensation deviation value to obtain the theoretical friction value.

[0014] Preferably, the method for determining the friction coefficient is as follows:

[0015] Collect the friction coefficients of each block, and calculate the friction of a certain drilling operation using the collected friction coefficients;

[0016] Aim at making the calculated friction infinitely close to the actual friction of the drilling operation, and perform inversion on the friction coefficient to obtain the optimal friction coefficient.

[0017] Preferably, the method for determining the compensation deviation value is as follows:

[0018] Obtain the simulated calculation friction and actual friction data of different drilling operations in the same block;

[0019] Calculate the deviation value between the simulated calculation friction and the actual friction of each drilling operation;

[0020] Take the average value of the deviation values of each drilling operation as the compensation deviation value.

[0021] Preferably, the optimization of the profile includes:

[0022] Change the depth of the build point, the holding angle or the build rate parameters respectively, and design several construction trajectories with different profile types;

[0023] Calculate the sliding drilling friction, rotary drilling torque, technical casing running friction and production casing running friction of each trip for each construction trajectory respectively;

[0024] Select the profile corresponding to the construction trajectory with the optimal comprehensive data among the sliding drilling friction, rotary drilling torque, technical casing running friction and production casing running friction data of each trip as the optimized profile.

[0025] Preferably, the designed profile types include the five-point six-section profile, the inclined plane circular arc profile or the double two-dimensional profile.

[0026] A directional buckling warning system based on drill string force analysis according to the present invention has a technical solution that includes:

[0027] A calculation module, configured to determine the critical friction value according to a pre-constructed friction statistics database; and calculate the theoretical friction value of the drilling operation according to the friction coefficient and the compensation deviation value;

[0028] A processing module, configured to output a normal construction signal when the theoretical friction value is less than the critical friction value; when the theoretical friction value is not less than the critical friction value, optimize the profile. If the theoretical friction value after optimization is less than the critical friction value, output a normal construction signal. If the theoretical friction value after optimization is still not less than the critical friction value, output a warning signal;

[0029] A warning module, configured to give a warning according to the warning signal.

[0030] The beneficial effects of the present invention are as follows: By determining the critical friction value and comparing the theoretical friction value with the critical friction value, the present method gives an early warning of the possible sticking phenomenon, greatly improves the drilling speed of the drilling stroke, and ensures the wellbore quality. In addition, when the sticking phenomenon may occur, the friction is reduced by optimizing the profile, that is, the present solution formulates a corresponding sticking treatment plan, which helps to quickly solve the possible directional sticking and further saves the construction period. The present invention has more remarkable effects on shale gas three-dimensional horizontal wells, especially horizontal wells with large offset distances and long horizontal sections. Description of the Drawings

[0031] Figure 1 It is a schematic flow chart of the implementation of a directional sticking warning method based on drill string force analysis according to the present invention;

[0032] Figure 2 It is a mechanical analysis graph of the lateral force in Table 4;

[0033] Figure 3 It is a mechanical analysis graph of the friction in Table 4;

[0034] Figure 4 It is a mechanical analysis graph of the axial stress in Table 4. Detailed Embodiment

[0035] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application clearer, the present application will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0036] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0037] It should be understood that the orientation or positional relationship indicated by terms such as "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present application.

[0038] In addition, the terms "first" and "second" are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present application, "a plurality" means two or more unless otherwise specifically defined.

[0039] Embodiment 1

[0040] Figure 1 shows a structural schematic diagram of a directional buckling warning method based on drill string force analysis provided by a preferred embodiment ( Figure 1 shows the first embodiment of the present application). For the convenience of description, only parts related to this embodiment are shown and are described in detail as follows:

[0041] Step 1: Determine the critical friction value according to the pre-constructed friction resistance statistical database.

[0042] The friction resistance statistical database is obtained by statistical analysis of the friction resistance during the directional process of the drilled wells in previous years when buckling occurs. According to statistics, among the wells with slight buckling (during the directional process, normal construction is ensured by adjusting drilling parameters and mud properties, changing the drilling method, and moving the drill string up and down), 78.57% of the wells have a friction resistance of 8 - 10T. Among the wells with severe buckling (normal construction can only be ensured by changing the bit type, adjusting the drill string assembly, or using supporting friction reduction tools), 86.67% of the wells have a friction resistance of more than 10T, with the highest reaching 16T, as shown in Table 1 specifically.

[0043] Table 1 Statistics of Buckling Conditions

[0044]

[0045]

[0046] Therefore, the critical friction value for slight buckling can be roughly determined as 8T, and the critical friction value for severe buckling is 10T. In this embodiment, the critical friction value for slight buckling, which is 8T, is used as the critical friction value of this solution.

[0047] Step 2: Calculate the theoretical frictional resistance of the drilling based on the frictional resistance coefficient and the compensation deviation value.

[0048] Collect the frictional resistance coefficients of each block, and calculate the frictional resistance of a certain well using the collected frictional resistance coefficients.

[0049] Taking the calculated frictional resistance being infinitely close to the actual frictional resistance of the well as the goal, perform inversion on the frictional resistance coefficient to obtain the optimal frictional resistance coefficient.

[0050] Based on the large amount of frictional resistance coefficients collected from each block in the early stage, using drill string force analysis software, by substituting the frictional resistance coefficient and adjusting the frictional resistance coefficient, the calculated frictional resistance can be made close to the actual frictional resistance, which is the inversion of the frictional resistance coefficient. The inversion of the frictional resistance coefficient needs to be verified by multiple wells to prove the universality of this coefficient in the same block. Taking the three wells of Jiaoye ba-2HF, Jiaoye bb-2HF, and Jiaoye bc-2HF as examples, first collect the frictional resistance values during the construction of the second openhole azimuth change of the three wells to obtain the actual frictional resistance of pulling up and lowering. Then, through the inversion calculation of the frictional resistance coefficient, it is found that when the frictional resistance coefficient in the casing section of the second openhole is 0.3 and in the openhole section is 0.4, it is closest to the actual frictional resistance, indicating that the frictional resistance coefficient in the second openhole of this block is 0.3 in the casing section and 0.4 in the openhole section. See Table 2 for details.

[0051] Table 2 Comparison between the frictional resistance calculated by the inverted frictional resistance coefficient and the actual frictional resistance

[0052]

[0053] To obtain the compensation deviation value, it is necessary to obtain the simulated calculated frictional resistance and actual frictional resistance data of different wells in the same block; calculate the deviation value between the simulated calculated frictional resistance and the actual frictional resistance of each well; take the average value of the deviation values of each well as the compensation deviation value. See Table 3 for details.

[0054] Table 3 Statistical analysis of deviation values

[0055]

[0056]

[0057] Through statistical analysis, it is found that the deviation between the simulated calculated frictional resistance value and the actual frictional resistance value in this block is basically between ±1.5T, and the average value of 0.8T is taken as the compensation deviation value.

[0058] After obtaining the frictional resistance coefficient, first calculate the initial theoretical frictional resistance value of the well based on the frictional resistance coefficient; then sum the initial theoretical frictional resistance value and the compensation deviation value to obtain the theoretical frictional resistance value.

[0059] Step 3: Use drill string force analysis software to calculate the sliding drilling friction. In the calculation, the influences of factors such as wellbore trajectory, drill string assembly, wellbore structure, mud density, drilling mode, and drilling pressure must be comprehensively considered. Finally, calculate the sliding drilling friction value. When the calculated theoretical friction value is less than the critical friction of 8T, normal construction can be carried out; when the theoretical friction value is not less than the critical friction of 8T, optimize the profile. If the theoretical friction value is less than the critical friction of 8T after optimization, normal construction can be carried out. If the theoretical friction value is still not less than the critical friction of 8T after optimization, give an early warning and formulate a corresponding treatment plan for sticking prevention in advance.

[0060] More preferably, the optimization of the profile includes:

[0061] Change the depth of the build point, the holding angle, or the build rate parameters respectively, and design several construction trajectories with different profile types;

[0062] Calculate the sliding drilling friction, rotary drilling torque, technical casing running friction, and production casing running friction for each trip of each construction trajectory respectively;

[0063] Select the profile corresponding to the construction trajectory with the best comprehensive data among the sliding drilling friction, rotary drilling torque, technical casing running friction, and production casing running friction data for each trip as the optimized profile.

[0064] More preferably, the designed profile types include the five-point six-section profile, the inclined plane circular arc profile, or the double two-dimensional profile.

[0065] In this embodiment, the warning prompt table is shown in Table 4. Among them, the mechanical analysis diagrams of lateral force, friction, and axial stress are as Figures 2 to 4 shown.

[0066] Table 4 XX Well Sticking Prevention Warning Prompt Table

[0067]

[0068] This method has been applied to more than 200 wells in the southwestern region, and the early warning effective rate is over 90%. It has a unique effect in shale gas three-dimensional horizontal wells, especially in horizontal wells with large offset and long horizontal section.

[0069] Embodiment 2

[0070] The present invention is applied to Well A with a 2,800-meter long horizontal section in the Fuling Shale Gas Field, belonging to a horizontal well with a large offset and reverse displacement long horizontal section. Through the statistics of the previous directional sticking friction data in this block, the critical friction for slight sticking can be roughly determined to be 8T, and the critical friction for severe sticking is 10T. The friction coefficient in the oil-based mud environment during the third drilling stage is 0.15 inside the casing and 0.20 in the open hole section. Through calculation, the sliding drilling friction in the second and third drilling stages of this well is relatively large, both exceeding the critical friction of 10T for severe sticking. Therefore, a sticking warning was promptly issued for this well, and the well profile was first optimized.

[0071] The optimization ideas are as follows: respectively change parameters such as the build point depth, holding angle, and build rate, and design three construction design trajectories: five-point six-section system, inclined plane arc, and double two-dimensional; calculate the friction torque in various working conditions such as rotary drilling and sliding drilling respectively.

[0072] Through friction simulation calculations for the three profiles respectively and analysis of the calculation results, the inclined plane arc has the smallest friction in sliding drilling at each drilling stage, rotary drilling torque, friction in running the technical casing, and friction in running the production casing, etc. Therefore, the inclined plane arc profile is preferably selected for construction. Specifically as shown in Table 5.

[0073] Table 5 Comparison of friction torque of three profiles

[0074]

[0075] After the well profile was optimized, the sliding drilling friction in the third drilling stage of this well still exceeded the critical friction of 8T for sticking. Therefore, a sticking warning was given to the drilling team, and corresponding technical measures were taken in advance. Finally, this well successfully completed the construction of the 2,800-meter horizontal section using a conventional directional drill string assembly.

[0076] A directional sticking warning system based on drill string force analysis according to the present invention, its technical solution is as follows:

[0077] A calculation module, used to determine the critical friction value according to a pre-constructed friction statistics database; and calculate the theoretical friction value of the drilling according to the friction coefficient and the compensation deviation value;

[0078] A processing module, used to output a normal construction signal when the theoretical friction value is less than the critical friction; when the theoretical friction value is not less than the critical friction, optimize the well profile. If the theoretical friction value after optimization is less than the critical friction, output a normal construction signal. If the theoretical friction value after optimization is still not less than the critical friction, output a warning signal;

[0079] A warning module, used to give a warning according to the warning signal.

[0080] It should be understood that the sequence numbers of the steps in the above embodiments do not indicate the order of execution, and the execution order of each process should be determined by its function and internal logic, and should not constitute any limitation to the implementation process of the embodiments of the present application.

[0081] The above embodiments are only used to illustrate the technical solutions of the present application, rather than limiting them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A directional drag warning method based on drill string force analysis, characterized in that: Determine the critical friction value according to the pre-constructed friction resistance statistical database; Calculate the theoretical friction resistance of the drilling according to the friction coefficient and the compensation deviation value; When the theoretical friction resistance is less than the critical friction resistance, normal construction is carried out; When the theoretical friction resistance is not less than the critical friction resistance, optimize the profile. If the theoretical friction resistance after optimization is less than the critical friction resistance, normal construction is carried out. If the theoretical friction resistance after optimization is still not less than the critical friction resistance, a warning is given; The friction resistance statistical database is obtained by statistical analysis of the friction resistance when the drag phenomenon occurs during the directional process of the drilled wells over the years; The method for determining the compensation deviation value is as follows: Obtain the simulated calculation friction resistance and actual friction resistance data of different drillings in the same block; Calculate the deviation value between the simulated calculation friction resistance and the actual friction resistance of each drilling; Take the average value of the deviation values of each drilling as the compensation deviation value; Calculating the theoretical friction resistance of the drilling according to the friction coefficient and the compensation deviation value includes: Based on the friction coefficient, calculate the initial theoretical friction resistance of the drilling; Sum the initial theoretical friction resistance and the compensation deviation value to obtain the theoretical friction resistance; The method for determining the friction coefficient is as follows: Collect the friction coefficients of each block, and calculate the friction resistance of a certain drilling using the collected friction coefficients; Taking the calculated friction resistance as infinitely close to the actual friction resistance of the drilling as the goal, invert the friction coefficient to obtain the optimal friction coefficient; The optimization of the profile includes: Respectively change the build point depth, holding angle or build rate parameter, and design several construction tracks with different profile types; Calculate the sliding drilling friction resistance, rotary drilling torque, technical casing running friction resistance and production casing running friction resistance of each run for each construction track respectively; Select the profile corresponding to the construction track with the best comprehensive data among the sliding drilling friction resistance, rotary drilling torque, technical casing running friction resistance and production casing running friction resistance data of each run as the optimized profile; The designed profile types include five-point six-section profile, inclined plane circular arc profile or double two-dimensional profile.

2. A system for implementing the method as described in claim 1, characterized in that: It includes A calculation module, used to determine the critical friction value according to the pre-constructed friction resistance statistical database; and calculate the theoretical friction resistance of the drilling according to the friction coefficient and the compensation deviation value; A processing module, used to output a normal construction signal when the theoretical friction resistance is less than the critical friction resistance; when the theoretical friction resistance is not less than the critical friction resistance, optimize the profile. If the theoretical friction resistance after optimization is less than the critical friction resistance, output a normal construction signal. If the theoretical friction resistance after optimization is still not less than the critical friction resistance, output a warning signal; A warning module, used to give a warning according to the warning signal.

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