Patent Application
20230020998
The present application claims the priority of Chinese patent application No. 201911295614.6, entitled “Well Drilling Tool and Method for Determining Parameter thereof” and filed on Dec. 16, 2019, the entire content of which is incorporated herein by reference.
The present invention relates to the technical field of well drilling, in particular to a drilling tool. The invention also relates to a method for determining parameters of the drilling tool. The drilling tool can be used for drilling speed enhancement in oil and gas exploration and exploitation, and in mines, quarries, geological investigations, water wells, geothermal fields, or the like as well.
With the developments of land deep/ultra-deep well drilling, deep-water offshore drilling, shale oil/gas exploitation and hot-dry rock geothermal resource exploitation, the fields of energy development and scientific drilling are constantly broadened. The formations encountered in drilling operations are more ancient with poor rock drillability, causing rather low drilling efficiency. This will directly result in gradually increasing drilling costs, so that there is an increasingly strong demand for speed enhancement in drilling. Rotary percussion drilling technology is one of the effective methods for rapid drilling, wherein various percussion drilling tools are adopted to drive a hammer through drilling fluid to generate a high-frequency percussive load, so that the rock will suffer volumetric fracture, thereby improving rock-breaking efficiency. This type of technology has been developed rapidly since its birth.
In recent years, China has carried out extensive researches on various drilling technologies, and has made breakthroughs in some fields. Especially, in the percussion drilling field, a variety of percussion drilling tools has been developed, which indicates an initial good prospect for speed enhancement. However, these tools are generally immature. The lifespan of percussion drilling tools in oil drilling applications has always been a bottleneck restricting the development of this technology.
Therefore, there is a need for a drilling tool that can improve the speed-enhancing mechanism of conventional percussion drilling tools as described above.
In view of some or all of the above problems, the present invention proposes a drilling tool. The present invention also proposes a method for determining parameters of the drilling tool. This drilling tool improves the speed-enhancing mechanism of conventional percussive drilling tools by combining the principles of rotary percussion drilling and elastic energy storage, thus achieving a major breakthrough in drilling technology. Especially, when applied to difficult-to-drill formations in the lower part of deep/ultra-deep wells, the drilling tool has significant speed-enhancing and efficiency-improving effects, indicating excellent application prospect. Moreover, the drilling tool is durable and has a long service life.
According to a first aspect of the present invention, a drilling tool is proposed, comprising an upstream drilling string, a downstream drilling bit, and a percussive device connected between the upstream drilling string and the downstream drilling bit. In a first state, the upstream drilling string is generated with elastic compression by the percussive device, and in a second state, the upstream drilling string releases the elastic compression to apply impacts on the downstream drilling bit through the percussive device.
Under the action of the percussive device, the upstream drilling string can be elastically compressed. The elastic compression of the upstream drilling string, when released, provides impacts for the percussive device. The impacts are transmitted to the downstream drilling bit, so that the downstream drilling bit can impact the formation. As a result, the drilling bit can impact the formation in rotary drilling, thus breaking the formation more easily. With this arrangement, it is more beneficial to improve the drilling efficiency and reduce the drilling cost.
In one embodiment, the percussive device comprises: a rotary driving part configured to be rotatable about its axis; a rotary working part, which has an upper end in engagement with a lower end of the rotary driving part and a lower end connected with the downstream drilling bit, wherein the rotary working part is configured to be driven by the rotary driving part to rotate about its axis, and axially movable relative to the rotary driving part; and a percussion generating part arranged around the rotary working part, the percussion generating part having an upper end abutting against the upstream drilling string and a lower end abutting against the rotary working part. In the first state, the percussion generating part moves upstream so that the upstream drilling string is generated with the elastic compression, and in the second state, the upstream drilling string releases the elastic compression, so that the percussion generating part moves downstream to apply impact on the rotary working part.
In one embodiment, the rotary driving part comprises a cylindrical driving rod, which has an upper end coupled with a power source. The rotary working part comprises a cylindrical rotary rod, which has an upper end in engagement with a lower end of the driving rod through a driving key, and a lower end connected with the downstream drilling bit. The upper end of the rotary rod is inserted into the lower end of the driving rod and provided at an outer side thereof with the driving key extending along an axial direction of the rotary rod, and the lower end of the driving rod is provided at an inner side thereof with a driving slot extending along an axial direction of the driving rod, wherein the driving key is fitted in the driving slot, so that the rotary rod is fixed relative to the driving rod along a circumferential direction, and movable relative thereto along the axial direction.
In one embodiment, the percussion generating part comprises a percussive sleeve, which is arranged around the rotary rod, and has a first sleeve segment with a relatively small inner diameter and a second sleeve segment with a relatively large inner diameter, the second sleeve segment being arranged below and connected with the first sleeve segment, wherein an upper driven tooth is formed at an inner side of the percussive sleeve in an area connecting the first sleeve segment with the second sleeve segment. The rotary rod includes a first rotating segment with a relatively small outer diameter and a second rotating segment with a relatively large outer diameter, the second rotating segment being arranged below and connected with the first rotating segment, wherein a lower driving tooth is formed on an outer side of the rotary rod in an area connecting the first rotating segment with the second rotating segment. The lower driving tooth and the upper driven tooth are configured to be in cooperation with each other, so that when the rotary rod rotates relative to the percussive sleeve, the percussive sleeve reciprocates axially relative to the rotary rod under the cooperation between the lower driving tooth and the upper driven tooth.
In one embodiment, the upper driven tooth and the lower driving tooth are each configured with an upward tooth segment inclined upstream in a direction opposite to a rotating direction, and a downward tooth segment inclined downstream in the direction opposite to the rotating direction, wherein an inclination of the upward tooth segment is smaller than that of the downward tooth segment.
In one embodiment, the rotary rod further comprises a third rotating segment, which is connected to a lower end of the second rotating segment and has an outer diameter larger than that of the second rotating segment, and a percussive step facing upstream is formed between the second rotating segment and the third rotating segment, so that the lower end of the percussive sleeve is opposite to and able to impact on the percussive step. An axial gap is formed between the upper driven tooth and the lower driving tooth when the lower end of the percussive sleeve is in contact with the percussive step.
In one embodiment, a cylindrical outer shell is arranged around the percussive sleeve, the outer shell being slidably engaged with the percussive sleeve through an orienting key, and having an upper end connected with the upstream drilling string. The percussive sleeve is provided at an outer side thereof with the orienting key extending axially, and the outer shell is provided at an inner side thereof with an orienting slot extending axially, the orienting key being fitted in the orienting slot so that the percussive sleeve is fixed relative to the outer shell in the circumferential direction, and movable relative thereto in the axial direction.
In one embodiment, the outer shell includes an upper shell portion connected to the upstream drilling string, and a lower shell portion located below and connected with the upper shell portion, at least a part of the driving rod being disposed within the upper shell portion, wherein a swivel bearing is provided between the upper shell portion and the driving rod to allow rotation of the driving rod relative to the upper shell portion. The lower shell portion surrounds the percussive sleeve. A lower end of the upper shell portion is inserted into an upper end of the lower shell portion, and a supporting sleeve is provided between the lower end of the upper shell portion and the upper end of the percussive sleeve, so that the percussive sleeve exerts a force on the upper shell portion through the supporting sleeve, thereby elastically compressing the upstream drilling string.
In one embodiment, the third rotating segment of the rotary rod is formed on a side wall thereof with a groove, in which a limiting block protruding radially outward relative to the third rotating segment is arranged. A cylindrical outer shell is arranged around the percussive sleeve and extends downward to surround the third rotating segment, and has an engaging portion extending radially inwardly at a lower end of the outer shell, wherein the limiting block is located upstream of the engaging portion, and configured to be able to abut against the engaging portion to restrict a downstream movement of the rotary rod relative to the outer shell.
According to a second aspect of the present invention, a method for determining parameters of the above drilling tool is proposed, wherein the upstream drilling string including a drill pipe and a drill collar located below and connected with the drill pipe. The method includes steps of: determining a value of a minimum percussive power required for drilling based on a compressive strength of rock of a formation to be drilled; determining a value of a preset percussive power based on the determined value of the minimum percussive power, wherein the value of the preset percussive power is not lower than that of the minimum percussive power; determining a minimum WOB required for drilling based on the value of the preset percussive power, and determining a torque value required for operations of the power source and the driving rod based on the minimum WOB required for drilling, and then determining a type of the power source and parameters of the driving rod, and then selecting and determining drilling parameters as required based on power source manual, wherein the drilling parameters include WOB, displacement or rotational speed, and/or determining structural parameters of the rotary rod and the percussive sleeve of the drilling tool based on the minimum WOB required for drilling, wherein the structural parameters include tooth number and tooth height of each of the lower driving tooth and the upper driven tooth.
Compared with the prior arts, the present invention has the advantages as follows. The drilling tool of the present application combines the principles of rotary percussion drilling and elastic energy storage, which improves the speed-enhancing mechanism of conventional percussion drilling tools, so that the drilling tool can impact the formation at a high frequency and a high stroke, thereby achieving easy formation-breaking. This can effectively improve drilling efficiency and reduce drilling cost. Moreover, when the drilling tool is applied to difficult-to-drill formations in the lower part of deep/ultra-deep wells, the effect of speed-enhancement and efficiency-enhancement is more significant.
In the following the present invention will be explained in more detail by way of illustrative exemplary embodiments with reference to the accompanying drawings. In the drawings:
In the drawings, the same reference numerals are used to indicate the same components. The drawings are not drawn to actual scale.
As shown in
The driving mechanism 20 includes a cylindrical housing, and a power source enclosed in the cylindrical housing. The housing is located downstream of the stabilizer 13 and connected therewith. For example, according to the parameters (such as WOB, displacement, torque, rotational speed, or the like) required for drilling operations, the driving mechanism 20 can be one of the followings: an upper assembly of a conventional screw-driving drilling tool, which includes a bypass valve assembly, an anti-drop assembly, a motor assembly, and a universal shaft assembly; an upper assembly of a special screw-driving drilling having high-torque structural parameters, which includes a special bypass valve assembly, a special anti-drop assembly, a special motor assembly, and a special universal shaft assembly; an upper assembly of a conventional turbodrill, which includes a turbine joint with a special impeller group, a turbine universal shaft and a turbine bearing section; and an upper assembly of a special turbodrill, which includes a turbine joint with a special impeller group, a special turbine universal shaft and a special turbine bearing section. That is, the power source may be a screw motor, a turbodrill, or the like. The structures of the above-mentioned driving mechanism 20 are all known in the field, and would not be repeated here.
The percussive device 30 includes a rotary driving part, which can be configured, for example, as a cylindrical driving rod 34 (
Specifically, an upper end of the static bearing ring 32 abuts against the screw, or an outer ring of the turbine bearing pack (since the driving mechanism 20 per se includes a bearing pack). At the same time, a second limiting step 321 facing downstream is provided on an outer wall of the static bearing ring 32, and accordingly, a first limiting step 311 facing upstream is provided on an inner wall of the upper shell portion 31. Upon assembly, the first limiting step 311 can cooperate with the second position limiting step 321 to restrict the static bearing ring 32 axially. The above arrangement ensures that the static bearing ring 32 is able to press the screw or the outer ring of the turbine bearing pack tightly. The movable bearing ring 33 is fixedly connected to an outer wall of the upper end of the driving rod 34 by means of, e.g., interference fit, with its upper end face abutting against the screw or an inner ring of the turbine bearing pack, and its lower end face abutting against a positioning shoulder 341 of the driving rod 34. In this manner, the movable bearing ring 33 may function to axially press the screw or the inner ring of the turbine bearing pack. With the swivel bearing, the driving rod 34 and the upper shell portion 31 are prevented from wear. In addition, opposite to an axial lower end of the static bearing ring 32 there is provided with a supporting sleeve 42 (described in detail below), so that the static bearing ring 32 can function to abut against its upstream and downstream members, and transmit force as well.
Downstream of the driving rod 34, a rotary working part is provided, which can be configured, for example, as a cylindrical rotary rod 43. At least a part of the rotary rod 43 is surrounded by the lower shell portion 41. As shown in
The percussive device 30 further includes a percussive sleeve 44, which is arranged around at least a part of the rotary rod 43. As shown in
As shown in
In a preferred embodiment, the wave-shaped upper driven tooth 441B and the wave-shaped lower driving tooth 432B each include an upward tooth segment, and a downward tooth segment connected therewith. As shown in
As shown in
In a preferred embodiment, as shown in
As shown in
As shown in
The fourth rotating segment 434 of the rotary rod 43 is located downstream of the wear-resistant joint 47. A step surface facing upstream is formed between the fourth rotating segment 434 and the third rotating segment 433. When the lower end surface 422B of the percussive sleeve 44 is in contact with the step surface 433B of the rotary rod 43, the step surface between the fourth rotating segment 434 and the third rotating segment 433 will be spaced apart from the downstream end surface of the wear-resistant joint 47.
In a preferred embodiment, as shown in
Preferably, the limiting block 45 can be configured as two semi-circular blocking shoes. After mounted, said two blocking shoes press tight the outer wall of the third rotating segment 433 at the groove, and are fixed on the outer wall of the third rotating segment 433 through a mounting wire 46. During tripping operations, the limiting block 45 along with the rotary rod 43 will be lowered relative to the lower shell portion 41, and then received on the wear-resistant joint 47, thus achieving anti-drop effect for the percussive sleeve 44, the rotary rod 43 and the limiting block 45.
The detailed working process of the above drilling tool 1 is as follows.
First, the above-described drilling tool 1 is lowered down to the well to be drilled. During this procedure, the rotary rod 43 moves downward relative to the driving rod 34 to a position where the limiting block 45 abuts against the upper end surface of the wear-resistant joint 47.
When the downstream drilling bit of the drilling tool 1 touches the bottom hole, the drilling tool 1 is continued to be lowered, so that the rotary rod 43 moves upward relative to the driving rod 34, until the upper end face of the percussive sleeve 44 abuts against the supporting sleeve 42.
Then, drilling operation starts. During operation, the downstream drilling bit acts on the formation. The rotary rod 43 and the downstream drilling bit rotate along with the driving rod 34. At the same time, the percussive sleeve 44 reciprocally moves up and down relative to the rotary rod 43. As the percussive sleeve 44 moves upward relative to the rotary rod 43, the drill rod 11 and the drill collar 12 of the upstream drilling string 10 will experience elastic compression. As the percussive sleeve 44 moves downward relative to the rotary rod 43, the elastic compression will be released, so that the percussive sleeve 44 will be pushed by the upstream drilling string 10 to move rapidly downward to impact on the rotary rod 43, thereby generating percussion of the downstream drilling bit toward the formation.
In order to design, manufacture and use the above drilling tool 1, a minimum WOB P1 of the drilling tool 1 should be determined first, and then structural parameters and drilling parameters of the drilling tool are obtained based on the minimum WOB P1.
In a first step, a minimum percussive power W0 required for drilling is determined according to a compressive strength Pr of the rock of the formation to be drilled.
In this step, rock of the formation to be drilled may firstly be sampled, and mechanical properties of the rock are analyzed for the sample taken. For example, lithology, drillability, hardness or the like of the sample can be determined here. The compressive strength Pr of the rock can then be determined from the drillability and hardness of the rock, e.g., according to the table below.
In addition, percussive crushing experiments at different compressive strengths can be performed for the rock of the formation to be drilled. According to the experimental results, the relationship between the percussive power W0 required for breaking the rock and the compressive strength of the rock is determined. For example, a regression curve of the relationship between the percussive power W0 required for breaking the rock and the compressive strength of the rock can be established. Therefore, after the compressive strength of the rock of the formation is determined, the value of the minimum percussive power W0 required for breaking the rock can be determined based on the above-mentioned relationship curve.
For example, for mudstone, W0=0.0034Pr2+0.325Pr+129.91; for sandstone, W0=0.0067Pr2+0.2196Pr+35.571; and for limestone, W0=0.0081Pr2−0.1702 Pr+45.464.
In a second step, according to the value of the minimum percussive power W0 required for breaking the rock, the value of a preset percussive power W for the drilling operation can be determined. The value of the preset percussive power W may be substantially equal to that of the minimum percussive power W0, or alternatively, greater than that of the minimum percussive power W0 if required.
In a third step, the minimum WOB P1 required for drilling is calculated according to the determined value of the preset percussive power W. The minimum WOB P1 required for drilling is the pressure exerted on the drilling tool 1 by an operator on ground during well drilling.
For example, the minimum WOB P1 can be calculated by the following formula:
wherein P1 is the minimum WOB required for drilling, W is the preset percussive power, h is the stroke of the percussive device, Lp is the length of the drill pipe, Ap is the cross-sectional area of the drill pipe, Ep is the elastic modulus of the drill pipe, Lc is the length of the drill collar, Ac is the cross-sectional area of the drill collar, and Ec is the elastic modulus of the drill collar.
The above parameters, such as the stroke h, the length Lp of the drill pipe, the cross-sectional area Ap of the drill pipe, the elastic modulus Ep of the drill pipe, the length Le of the drill collar, the cross-sectional area Ac of the drill collar, the elastic modulus Ec of the drill collar or the like, can each be preset to a value. If the value of the minimum WOB P1 does not meet the actual drilling requirements, at least one of the above-mentioned parameters can be re-determined and re-calculated, until the minimum WOB P1 as calculated is within the applicable range of drilling.
In a fourth step, in the method for designing and manufacturing the drilling tool 1, after the above-mentioned minimum WOB P1 is obtained by calculation, a torque value required for operations of the power source (e.g., the screw motor and the turbodrill) and the driving rod 34 can be determined according to the minimum WOB P1, and based on which, the type of the power source and the parameters of the driving rod 34 can be determined. Accordingly, all drilling parameters can be selected and determined based on a design manual for the power source. For example, the drilling parameters may include WOB, displacement, rotational speed, or the like.
In a fifth step, key structural parameters of core members of the tool, i.e., the rotary rod 43 and the percussive sleeve 44, are determined according to the minimum WOB P1 and the stroke h. For example, the key structural parameters may include tooth number and tooth height of each of the lower driving tooth and the upper driven tooth.
As an alternative, according to the needs of the drilling site, the value of the minimum WOB P1 can also be preset, and the value of the preset percussive power W can be determined according to the preset value of the minimum WOB P1. Then, the value of the preset percussive power W is compared with that of the minimum percussive power W0. If the value of the preset percussive power W is substantially greater than or equal to that of the minimum percussive power W0, the preset value of the minimum WOB P1 can be used in subsequent operations. Otherwise, the value of the minimum WOB P1 and/or the value of at least one of the above parameters should be re-preset, and calculation is performed again, until the value of the preset percussive power W is substantially greater than or equal to that of the minimum percussive power W0.
The drilling tool 1 described above is particularly suitable for vertical well drilling in hard formation environments with a depth exceeding several thousand meters. The length of the drill pipe is at least ten times the stroke h. Assuming that the lower part of the drilling string is a 200 m drill collar, when the well depth is greater than 200 m plus 10 times the length of the stroke (h), the drill pipe has a relatively small rigidity, and can be considered as an elastic drilling string. At this time, the deformation is mainly caused by the drill pipe.
For example, thrust augment required for achieving a certain stroke (for example, 10 mm) will decrease rapidly with the increase of the drill pipe. The calculation results show that as long as a 100 m drill pipe is connected, the required thrust augment will decrease rapidly from 17.92t to 4.38t, and then gradually approach 0.
The drilling tool 1 according to the present invention is based on composite dual-drive and elastic energy storage of the upstream drilling string 10. In operation, the upstream drilling string 10 can be compressed and recovered, and during the downward recovering procedure, potential energy will drive the downstream drilling bit to impact the formation reciprocally, generating a comprehensive effect of high-speed rotation and high-frequency percussion. Therefore, the drilling tool 1 according to the present invention has the advantages of high rock-breaking frequency, strength and efficiency, achieving an improved speed-enhancing effect. The upstream drilling string 10 can provide much greater elastic compression than elastic members commonly used in the field (e.g., helical springs, disc springs, etc.). Accordingly, the downstream drilling bit is allowed to generate percussion of relatively high frequency and magnitude, which is more beneficial to improve the drilling speed and drilling efficiency of the drilling tool 1.
In addition, the above drilling tool 1 does not have any weak part in structure, which is beneficial to improve the structural stability of the drilling tool 1 and prolong the service life of the drilling tool 1.
Although the present invention has been described with reference to the preferred embodiments, various modifications may be made and equivalents may be substituted for components thereof without departing from the scope of the present invention. In particular, under the condition that there is no structural conflict, each technical feature mentioned in each embodiment can be combined in any manner. The present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 201911295614.6 | Dec 2019 | CN | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/CN2020/114857 | 9/11/2020 | WO |
