A new drilling tool assembly and drilling parameter optimization method based on vertical drilling system

Abstract

The present invention provides a novel drill tool combination based on a vertical drilling system and a drilling parameter optimization method. In order to achieve anti-deflection and fast drilling, the vertical drilling system is often combined with a screw drill tool. The novel drill tool combination is composed of a drill bit, a straight screw drill tool, a vertical drilling tool, a short drill collar, a drill string stabilizer and an upper drill string connected in sequence. The drill tool combination can change the existing vertical drilling system from a push-type working principle to a pointing type working principle. The use method and the deflection correction principle are completely different from those of the existing drill tool combination, which not only helps to improve the deflection correction ability of the existing vertical drilling system, but also avoids the failure of the bearing of the vertical drilling system and the use of high-cost special screw drill tools, thereby achieving the dual purposes of anti-deflection and fast drilling and reducing drilling costs.

Description

Technical Field

[0001] The invention belongs to the field of petroleum drilling engineering, and in particular to the research and application of vertical well deviation control technology, and specifically to a new drilling tool combination based on a vertical drilling system and a drilling parameter optimization method. Background Art

[0002] Well deflection is a very important practical problem in the process of oil and gas drilling, especially in geological conditions such as high-steep structures, faults, and salt layers. Due to the complex formation conditions and the difficulty of drilling, in serious cases, the well needs to be filled and re-drilled or scrapped, resulting in a long drilling cycle, high drilling costs, and even failure to achieve the purpose of exploration and development. In order to solve the well deflection problem, drilling technicians have proposed anti-deflection and correction technologies such as pendulum drilling tools, full-eye drilling tools, eccentric drilling tools, and eccentric drilling tools. However, with the increasing difficulty of oil and gas development and geological exploration, the above-mentioned anti-deflection and correction technologies have shown their limitations. For example, in order to achieve the deflection correction effect, the pendulum drilling tool reduces its drilling pressure, resulting in a significant reduction in its drilling speed. The full-eye drilling tool increases the rigidity and size of the drilling tool to keep the drilling tool centered in the well, thereby reducing the deflection angle of the drill bit, thereby reducing and limiting the deflection-increasing force caused by the bending of the drill string, and at the same time increases the number of stabilizers to limit the lateral movement of the drill bit, thereby achieving the purpose of deflection correction and reduction. However, the use of full-eye drilling tools requires at least three stabilizers, which greatly increases the friction during the drilling process.

[0003] Automatic vertical drilling technology automatically tracks the predetermined wellbore trajectory without human intervention, and can successfully solve the problem of preventing and correcting deflection in high-steep structures and complex formations with large dip angles. In order to prevent deflection and drill quickly, a low-speed, high-torque screw drill tool is usually placed above the vertical drilling system. The drill tool assembly is "drill bit 01 + vertical drilling tool 02 + drill string stabilizer 03 + straight screw drill tool 04 + upper drill string 05", as shown in the attached figure. Figure 1 As shown. Two important problems need to be solved before using this drill bit combination. On the one hand, when using screw drill bits, the spindle speed of the vertical drilling tool is relatively high, which requires the vertical drilling system to use high-speed bearings. Domestic vertical drilling systems currently lack high-speed bearings; on the other hand, when using screw drill bits, the starting load is relatively large, and the working capacity of the screw drill bits is required to be high. It is necessary to use imported special screw drill bits, which increases drilling costs. In order to avoid the failure of the bearings of the vertical drilling system and the use of high-cost special screw drill bits, the present invention provides a new drill bit combination based on a vertical drilling system and a drilling parameter optimization method, which not only helps to improve the deflection correction capability of the existing vertical drilling system, but also avoids the failure of the bearings of the vertical drilling system and the use of high-cost special screw drill bits, thereby achieving the dual purposes of preventing deflection and reducing drilling costs. Summary of the invention

[0004] In order to avoid bearing failure of the vertical drilling system and the use of high-cost special screw drill tools, and to improve the deflection correction capability of the drilling system, the present invention provides a new drill tool combination based on the vertical drilling system and a drilling parameter optimization method, which improves the deflection correction capability of the existing vertical drilling system and can also avoid bearing failure of the vertical drilling system and the use of high-cost special screw drill tools, thereby achieving the dual purposes of preventing deflection and drilling faster and reducing drilling costs.

[0005] A new type of drilling tool combination based on a vertical drilling system, the new type of drilling tool combination is formed by connecting a drill bit, a straight screw drill tool, a vertical drilling tool, a short drill collar, a drill string stabilizer and an upper drill string in sequence, the vertical drilling tool is provided with guide ribs, the vertical drilling system is a directional drilling system, the guiding force generated by the vertical drilling system pushes the vertical drilling tool from the lower side of the wellbore to the higher side of the wellbore, and the drill bit rotation angle direction points to the lower side of the wellbore.

[0006] Furthermore, after adopting the novel drilling tool combination, if the guiding force is directed from the high side of the wellbore to the low side of the wellbore, although the lateral force of the drill bit is less than 0, the drill bit angle and the rate of change of the well inclination are both greater than 0, and the drilling effect is to increase the inclination; if the guiding force is directed from the low side of the wellbore to the high side of the wellbore, although the lateral force of the drill bit is greater than 0, the drill bit angle and the rate of change of the well inclination are both less than 0, and the drilling effect is to decrease the inclination.

[0007] The drilling parameter optimization method of the novel drilling tool assembly based on the vertical drilling system is adopted, and the drilling parameter optimization method comprises the following steps:

[0008] Step 1: Select the length of the straight screw drill, the drill bit model and the diameter of the drill string stabilizer according to the drilling formation requirements;

[0009] Step 2: Select medium drilling pressure and medium guiding force, predict the well inclination change rate corresponding to different short drill collar lengths based on the drilling tool assembly mechanical model and the balanced trend inclination rate prediction method, and select the short drill collar length;

[0010] Step 3: Select a drilling pressure value that is suitable for the formation characteristics according to the formation characteristics, predict the well inclination change rate corresponding to different guiding forces based on the drilling tool assembly mechanical model and the balanced trend inclination rate prediction method, and select a suitable guiding force;

[0011] Step 4: Drill according to the determined short drill collar length and guiding force. During the drilling process, adjust the drilling pressure or guiding force in time according to actual needs to drill the formation. Increasing the drilling pressure or guiding force will help improve the deflection correction capability, and vice versa, the drilling pressure or guiding force can be reduced.

[0012] Furthermore, the entire lower drilling tool assembly is divided into three spans and three supports. The first span is from the drill bit center to the upper end face of the straight screw drilling tool, the second span is from the lower end face of the vertical drilling tool to the center of the drill string stabilizer, and the third span is above the center of the drill string stabilizer. The three supports are virtual supports, drill string stabilizers, and contact points between the upper drill string and the well wall. The virtual supports are at the connection between the straight screw drilling tool and the vertical drilling tool. The mechanical model of the drilling tool assembly is:

[0013]

[0014] q3L 4 X(u3)+8M3Y(u3)L3 2 +4M2Z(u3)L3 2 =24EI3[kL3(L1+L 21 +L 22 +L3)-y3+y2] (3)

[0015]

[0016] Where: M i is the internal bending moment at the i-th support (i=1~3);

[0017] X(u i )、Y(u i )、Z(u i ) is the magnification factor of the i-th span beam and column;

[0018] I i ,q i , L i are the moment of inertia, linear weight and length of the i-th span beam respectively; L21 and L22 represent the length of the vertical drilling tool and the short drill collar respectively

[0019] F is the guiding force;

[0020] y i is the ordinate of the i-th support;

[0021] P i is the axial force on each span beam;

[0022] K is the wellbore curvature;

[0023] E is the elastic modulus.

[0024] Furthermore, by solving the mechanical model of the drill tool assembly, the calculation formulas for the drill bit lateral force and the drill bit rotation angle are obtained:

[0025]

[0026] Where: N b is the drill bit lateral force;

[0027] A t is the drill bit angle;

[0028] P B For drilling pressure.

[0029] Further, according to the obtained drill bit lateral force and drill bit rotation angle, the drilling trend angle is calculated using the drill bit and formation interaction model. The drilling trend angle A is r The calculation formula is as follows:

[0030]

[0031] In the formula, I b is the drill bit anisotropy index.

[0032] Furthermore, the second span beam includes a vertical drilling tool, a short drill collar and a half drill string stabilizer.

[0033] Furthermore, the build-up rate corresponding to the drilling tool assembly and drilling parameters is obtained according to the balanced trend build-up rate prediction method.

[0034] Furthermore, the drilling parameters include drilling pressure and thrust.

[0035] Furthermore, when the value of the build-up rate is less than 0, it is called a falling slope.

[0036] Beneficial effect: the combined guiding force generated by the vertical drilling system pushes the vertical drilling tool from the lower side of the wellbore to the higher side of the wellbore (completely opposite to the direction of the existing guiding force and the lateral force of the drill bit, which is not conducive to deflection correction), and the drill bit rotation angle is directed to the lower side of the wellbore (completely opposite to the direction of the existing drill bit rotation angle, which is conducive to deflection correction). By optimizing the drill tool assembly and drilling parameters, the positive impact of the drill bit rotation angle on the deflection correction effect is far greater than the negative impact corresponding to the lateral force of the drill bit, ensuring that the new drill tool assembly has a strong deflection correction ability. The present invention not only helps to improve the deflection correction ability of the existing vertical drilling system, but also avoids the failure of the bearings of the vertical drilling system and the use of high-cost special screw drill tools, achieving the dual purposes of preventing deflection and reducing drilling costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 Schematic diagram of a drilling tool assembly of a vertical drilling system in the prior art;

[0038] Figure 2 Schematic diagram of the drilling tool assembly of the new vertical drilling system;

[0039] Figure 3 Schematic diagram of the existing vertical drilling tool assembly deflection correction principle;

[0040] Figure 4 Schematic diagram of the deflection correction principle of the new vertical drilling assembly;

[0041] Figure 5 Schematic diagram of mechanical analysis of the new vertical drilling tool assembly;

[0042] Figure 6 The diagram of the variation of the deflection correction effect with the length of the short drill collar;

[0043] Figure 7 The diagram of the correction effect changing with drilling pressure;

[0044] Figure 8 Diagram showing the law of the correction effect changing with the guiding force;

[0045] Fig. 9 Basic flow chart of the balanced trend slope prediction method. DETAILED DESCRIPTION

[0046] In order to make the purpose, technical scheme and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention, that is, the embodiments described are only part of the embodiments of the present invention, rather than all of the embodiments.

[0047] (1) Overall design and use of new drilling tool assembly

[0048] A new type of drilling tool assembly based on a vertical drilling system, the new type of drilling tool assembly is composed of a drill bit 1, a straight screw drilling tool 5, a vertical drilling tool 2, a short drill collar 7, a drill string centralizer 4 and an upper drill string 6 connected in sequence, and a guide rib 3 is arranged on the vertical drilling tool.

[0049] The existing drilling tool assembly is "drill bit 01 + vertical drilling tool 02 + drill string stabilizer 04 + straight screw drilling tool 05 + upper drill string 06", and the vertical drilling tool is provided with a guide rib 03, such as Figure 1 As shown in FIG. 1 , the basic form of the new drilling tool assembly is “drill bit 01 + straight screw drilling tool 05 + vertical drilling tool 02 + short drill collar 07 + drill string stabilizer 04 + upper drill string 06”. Figure 2 This drilling tool assembly changes the existing vertical drilling system from a push-type working principle to a pointing working principle. Its usage method and deflection correction principle are completely different from those of the existing drilling tool assembly. Figure 3 and Figure 4. The guiding force generated by the vertical drilling system in the present invention pushes the vertical drilling tool from the lower side of the wellbore to the higher side of the wellbore (completely opposite to the direction of the existing guiding force and the lateral force of the drill bit, which is not conducive to deflection correction), and the direction of the drill bit angle points to the lower side of the wellbore (completely opposite to the direction of the existing drill bit angle, which is conducive to deflection correction). The present invention optimizes the drill tool combination and drilling parameters so that the positive impact of the drill bit angle on the deflection correction effect is far greater than the negative impact corresponding to the lateral force of the drill bit, thereby ensuring that the new drill tool combination has a strong deflection correction ability. The present invention not only helps to improve the deflection correction ability of the existing vertical drilling system, but also avoids the failure of the bearings of the vertical drilling system and the use of high-cost special screw drill tools, thereby achieving the dual purposes of preventing deflection and speeding up drilling and reducing drilling costs.

[0050] The analysis results of an example are shown in Figure 6 It can be seen that after adopting the new drilling tool assembly, if the guiding force is still directed from the high side of the wellbore to the low side of the wellbore (the suffix "push down"), although the lateral force of the drill bit is less than 0, the drill bit angle and the rate of change of the well inclination are both greater than 0, and the actual drilling effect is to increase the inclination, rather than to decrease the inclination; if the guiding force is changed from the low side of the wellbore to the high side of the wellbore (the suffix "push up"), although the lateral force of the drill bit is greater than 0, the drill bit angle and the rate of change of the well inclination are both less than 0, and the actual drilling effect is to decrease the inclination.

[0051] (2) Analysis and solution of drilling tool assembly mechanical model

[0052] The longitudinal and transverse bending beam method is used to establish the drilling tool assembly stress analysis model. Figure 5 Based on the structure and working principle of the push-type vertical drilling tool, the vertical drilling tool and the guiding force are equivalent to a concentrated force, the connection between the screw drill and the vertical drilling tool is equivalent to a virtual support, and the entire lower drilling tool assembly is divided into three spans and three supports (virtual support, drill string stabilizer, and the intersection point between the drill string and the well wall). Among them, the first span is from the center of the drill bit to the upper end face of the screw drill, the second span is from the lower end face of the vertical drilling tool to the center of the drill string stabilizer (including the vertical drilling tool, the short drill collar and half of the drill string stabilizer), and the drill string above the drill string stabilizer is the third span.

[0053] Finally, the basic equations corresponding to the drilling tool assembly mechanical model are obtained:

[0054]

[0055] q3L 4 X(u3)+8M3Y(u3)L3 2 +4M2Z(u3)L3 2 =24EI3[kL3(L1+L2+L2+L3)-y3+y2] (3)

[0056]

[0057] Where: Mi is the internal bending moment at the i-th support (i=1~3);

[0058] X(u i )、Y(u i )、Z(u i ) is the magnification factor of each i-th span beam and column;

[0059] I i ,q i , L i are the moment of inertia, linear weight and length of the i-th span beam respectively;

[0060] F is the guiding force;

[0061] y i is the ordinate of the i-th support.

[0062] P i is the axial force on each span beam;

[0063] K is the wellbore curvature.

[0064] After solving the above equations, the drill bit lateral force and drill bit rotation angle can be obtained:

[0065]

[0066] (3) Solution of the equilibrium trend slope prediction method

[0067] The lateral force and inclination of the drill bit can be obtained by using the mechanical model of the lower drilling tool assembly. Then, the drilling trend angle can be calculated by using the interaction model between the drill bit and the formation, providing basic data for the prediction of the build-up rate.

[0068] Drilling trend angle (A r )The calculation formula is shown in formula (7).

[0069]

[0070] In the formula, I b is the drill bit anisotropy index; the meanings of other variables are the same as above.

[0071] Finally, the inclination rate corresponding to the current drilling tool assembly and drilling parameters is calculated according to the basic process of the balanced trend inclination rate prediction method. The balanced trend inclination rate prediction process is as follows: Fig. 9 As shown in the figure, the estimated value of the build-up rate is given first, and then the RSBHA mechanical model is solved to find the drill bit lateral force and drill bit rotation angle; then the well inclination trend angle A is found. r Then judge whether it satisfies |A r|≈0; if the condition is met, the trial calculation is stopped, and the wellbore curvature corresponding to the trial calculation result is the build-up rate of the given drilling conditions; otherwise, the build-up rate is re-estimated and the above process is repeated until the trial calculation termination condition is met.

[0072] The inclination rate obtained at this time is the change rate of well inclination corresponding to the vertical drilling system under the current conditions (when this value is less than 0, it is called the slope reduction rate). The inclination rate prediction method integrates the mechanical model of the drilling tool assembly and the interaction model between the drill bit and the formation. It can comprehensively consider the influence of factors such as the drilling tool structure, wellbore geometry, drilling parameters, drill bit and formation characteristics on the inclination rate, and can reveal the influencing factors and laws of the inclination correction ability of the new vertical drilling assembly.

[0073] (4) Drilling tool assembly and drilling parameter optimization

[0074] By solving the above mechanical model and the well inclination change rate corresponding to the given conditions through programming, the influence of drilling tool assembly structural parameters (beam length per span, stabilizer diameter and position), drilling pressure, guiding force, drill bit anisotropy, and formation anisotropy index on the deflection correction effect can be analyzed. Based on the analysis of the factors and rules affecting the deflection rate, the drilling tool assembly design can be optimized and the drilling parameters can be selected to obtain the best deflection correction effect.

[0075] Taking a domestic vertical drilling system as an example, the default calculation parameters are: drill bit diameter 333.5mm, current well inclination angle 1°; vertical drilling tool outer diameter 230mm, guide force 15kN; screw drill length 9.45m; short drill collar length 5.0m; stabilizer diameter 329mm; drilling pressure 120kN; drill bit anisotropy index 0.04. The influence of short drill collar length, drilling pressure, and guide force on the correction effect are shown in Figure 6 (The legend ends with "Push Up"), Figure 7 and Figure 8 It can be seen that appropriately lengthening the short drill collar and appropriately increasing the drilling pressure and guiding force are all helpful to improve the deflection correction capability.

[0076] A drilling parameter optimization method for a new drilling tool assembly based on a vertical drilling system is adopted, and the drilling parameter optimization method comprises the following steps:

[0077] Step 1: Select the length of the straight screw drill, the drill bit model and the diameter of the drill string stabilizer according to the drilling formation requirements;

[0078] Step 2: Select medium drilling pressure and medium guiding force, predict the well inclination change rate corresponding to different short drill collar lengths based on the drilling tool assembly mechanical model and the balanced trend inclination rate prediction method, and select the short drill collar length;

[0079] Step 3: Select a drilling pressure value that is suitable for the formation characteristics according to the formation characteristics, predict the well inclination change rate corresponding to different guiding forces based on the drilling tool assembly mechanical model and the balanced trend inclination rate prediction method, and select a suitable guiding force;

[0080] Step 4: Drill according to the determined short drill collar length and guiding force. During the drilling process, adjust the drilling pressure or guiding force in time according to actual needs to drill the formation. Increasing the drilling pressure or guiding force will help improve the deflection correction capability, and vice versa, the drilling pressure or guiding force can be reduced.

[0081] Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by technicians in this technical field within the essential scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. A drilling parameter optimization method using a new drilling tool assembly based on a vertical drilling system is characterized in that: The novel drilling tool assembly is formed by connecting a drill bit, a straight screw drilling tool, a vertical drilling tool, a short drill collar, a drill string stabilizer and an upper drill string in sequence. The vertical drilling tool is provided with a guide rib. The vertical drilling system is a directional drilling system. The guide force generated by the vertical drilling system pushes the vertical drilling tool from the lower side of the wellbore to the higher side of the wellbore, and the drill bit rotation direction points to the lower side of the wellbore. After adopting the novel drilling tool assembly, if the guide force points from the higher side of the wellbore to the lower side of the wellbore, although the drill bit lateral force is less than 0, the drill bit rotation angle and the well inclination change rate are both greater than 0, and the drilling effect is to increase the inclination. If the guide force points from the lower side of the wellbore to the higher side of the wellbore, although the drill bit lateral force is greater than 0, the drill bit rotation angle and the well inclination change rate are both less than 0, and the drilling effect is to decrease the inclination. The drilling parameter optimization method comprises the following steps: Step 1: Select the length of the straight screw drill, the drill bit model and the diameter of the drill string stabilizer according to the drilling formation requirements; Step 2: Select medium drilling pressure and medium guiding force, predict the well inclination change rate corresponding to different short drill collar lengths based on the drilling tool assembly mechanical model and the balanced trend inclination rate prediction method, and select the short drill collar length; Step 3: Select a drilling pressure value that is suitable for the formation characteristics according to the formation characteristics, predict the well inclination change rate corresponding to different guiding forces based on the drilling tool assembly mechanical model and the balanced trend inclination rate prediction method, and select a suitable guiding force; Step 4: Drilling is performed according to the determined short drill collar length and guiding force. During the drilling process, the drilling pressure or guiding force is adjusted in time according to actual needs to perform formation drilling. Increasing the drilling pressure or guiding force is helpful to improve the deflection correction capability, and vice versa, reducing the drilling pressure or guiding force. The entire lower drilling tool assembly is divided into three spans and three supports. The first span is from the drill bit center to the upper end face of the straight screw drilling tool, the second span is from the lower end face of the vertical drilling tool to the center of the drill string stabilizer, and the third span is above the center of the drill string stabilizer. The three supports are virtual supports, drill string stabilizers, and contact points between the upper drill string and the well wall. The virtual supports are at the connection between the straight screw drilling tool and the vertical drilling tool. The mechanical model of the drilling tool assembly is: <h2 style=";text-align:left;direction:ltr">q3L3<h2 style=";text-align:left;direction:ltr"> 4 <h2 style=";text-align:left;direction:ltr"> X(u3)+8M3Y(u3)L3<h2 style=";text-align:left;direction:ltr"> 2 <h2 style=";text-align:left;direction:ltr"> +4M2Z(u3)L3<h2 style=";text-align:left;direction:ltr"> 2 <h2 style=";text-align:left;direction:ltr"> =24EI3[kL3(L1+L<h2 style=";text-align:left;direction:ltr"> 21 <h2 style=";text-align:left;direction:ltr"> +L<h2 style=";text-align:left;direction:ltr"> 22 <h2 style=";text-align:left;direction:ltr"> +L3)-y3+y2](3) Where: M i is the internal bending moment at the i-th support (i=1~3); X(u i )、Y(u i )、Z(u i ) is the magnification factor of the i-th span beam and column; I i ,q i , L i are the moment of inertia, linear weight and length of the i-th span beam respectively; L21 and L22 represent the length of the vertical drilling tool and the short drill collar respectively; F is the guiding force; y i is the ordinate of the i-th support; P i is the axial force on each span beam; K is the wellbore curvature; E is the elastic modulus.

2. The method for optimizing drilling parameters of a new drilling tool assembly based on a vertical drilling system according to claim 1, characterized in that: By solving the mechanical model of the drilling tool assembly, the calculation formulas for the drill bit lateral force and the drill bit rotation angle are obtained: Where: N b is the drill bit lateral force; A t is the drill bit angle; P B For drilling pressure.

3. The method for optimizing drilling parameters of a new drilling tool assembly based on a vertical drilling system according to claim 2, characterized in that: According to the obtained drill bit lateral force and drill bit rotation angle, the drilling trend angle is calculated using the drill bit and formation interaction model. The drilling trend angle A is r The calculation formula is as follows: In the formula, I b is the drill bit anisotropy index.

4. The method for optimizing drilling parameters of a new drilling tool assembly based on a vertical drilling system according to claim 1, characterized in that: The second span beam comprises a vertical drilling tool, a short drill collar and a half drill string centralizer.

5. The drilling parameter optimization method of a new drilling tool assembly based on a vertical drilling system according to claim 1, characterized in that: The build-up rate corresponding to the drilling tool assembly and drilling parameters is obtained according to the balanced trend build-up rate prediction method.

6. The method for optimizing drilling parameters of a new drilling tool assembly based on a vertical drilling system according to claim 5, characterized in that: The drilling parameters include drilling pressure and thrust force.

7. The method for optimizing drilling parameters of a new drilling tool assembly based on a vertical drilling system according to claim 5, characterized in that: When the value of the build-up rate is less than 0, it is called the falling slope.

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