Downhole measurement-while-drilling apparatus

Abstract

This invention provides a downhole measurement-while-drilling (MWD) device, comprising an upstream functional sub and a downstream functional sub connected to each other via a joint mechanism. The joint mechanism includes an upper body fixedly connected to the upstream functional sub and a lower body fixedly connected to the downstream functional sub. An upper conductor embedded in the upper body is electrically connected to a lower conductor embedded in the lower body. The lower body includes a recessed first free-moving groove, and the upper body includes a protruding first free-rotating head that extends into and is freely movable within the first free-moving groove.

Description

Technical Field

[0001] This invention relates to measuring instruments used in oil and gas exploration and development, specifically to a downhole measurement while drilling device, particularly for downhole measurement while drilling devices for wellbores with large curvature and short radius. Background Technology

[0002] Old oil and gas fields will enter a period of declining production after long-term development, leading to increased extraction difficulties and rising development costs.

[0003] Therefore, sidetracking technology for old wells is commonly used to increase oil and gas production. The principle of this technology is to use special drilling tools and measurement-while-drilling instruments to perform directional sidetracking in old wells, ultimately controlling the well inclination angle to about 90 degrees, and maintaining this angle to drill a certain length of well section, thereby increasing the length of the target formation and increasing the drainage area.

[0004] Due to the high precision requirements for target alignment, sidetracking in older wells typically requires a large curvature and a short radius when transitioning from a vertical to a horizontal section. However, drilling with a large curvature and short radius wellbore trajectory in older wells requires both the drilling tools and the measurement-while-drilling (MWD) instruments to have significant flexibility. This is necessary to ensure smooth passage through the sidetracking section and maintain consistency between the MWD instruments and the drilling tools, especially the screw, to ensure the smooth implementation of directional drilling.

[0005] Drilling tools are purely mechanical tools, with a total length of several kilometers. Due to their length, highly flexible metal materials are typically chosen to allow for significant bending. Measurement-while-drilling (MWD) instruments usually refer to probe-type instruments, where the measurement unit is arranged inside the probe, which is installed inside the drill collar. The drill collar is then connected to the drill string assembly and lowered into the well for drilling operations. Existing MWD instruments consist of pulse generator subs, measurement probe subs, power supply subs, etc., all rigidly connected by threads, with a total length varying from 5 to 10 meters. Therefore, the bending of the entire MWD instrument relies solely on the flexibility of the sub steel (or other alloy materials), resulting in a very small bending angle. Forcing significant bending between the subs would require the external pressure tank of the MWD instrument to withstand considerable pressure, and internal components such as circuit boards and sensors would be easily damaged. Therefore, traditional MWD instruments cannot traverse well sections with large curvature and short radii.

[0006] Wireline logging and measurement while drilling (MWD) face similar challenges. Existing wireline logging (including open-hole logging, production logging, and annular logging) instrument assemblies use flexible sections to increase flexibility; once the instruments are interconnected via these flexible sections, relative rotation angles are not a concern. However, existing MWD instruments use rigid connections between sections, with a fixed relative angle between the measuring probe and the build-up screw. Therefore, if the flexible connection method widely used in wireline logging is introduced into MWD, it is necessary to ensure that the probe and screw cannot rotate relative to each other. Otherwise, even if the measuring probe is positioned at a certain toolface angle, it cannot be guaranteed that the screw's bend point is at a specific toolface angle. In this case, if sliding drilling occurs, the drilling direction cannot be guaranteed. Furthermore, the environment during MWD is much harsher than that of wireline logging. MWD instruments must withstand significant vibrations during drilling, and flexible connections are weak points in this vibration, making vibration damping at these locations extremely difficult. Summary of the Invention

[0007] To address the aforementioned deficiencies in existing technologies, the present invention aims to provide a measurement-while-drilling (MWD) device capable of adapting to wellbores with large curvature and short radius. Compared to conventional MWD devices, the MWD device according to the present invention has increased instrument flexibility, thereby better adapting to the MWD requirements under complex conditions such as sidetracking in older wells.

[0008] According to the present invention, a downhole measurement-while-drilling (MWD) device is provided, comprising an upstream functional sub and a downstream functional sub connected to each other via a joint mechanism. The joint mechanism includes an upper body fixedly connected to the upstream functional sub and a lower body fixedly connected to the downstream functional sub. An upper conductor embedded in the upper body is electrically connected to a lower conductor embedded in the lower body. The lower body includes a recessed first free-moving groove, and the upper body includes a protruding first free-rotating head that extends into and is capable of free movement within the first free-moving groove.

[0009] In a preferred embodiment, the first free-rotating head includes a recessed second free-moving groove, the first free-moving groove including a second free-rotating head extending from the bottom surface, the second free-rotating head extending into the second free-moving groove and being able to move freely within the second free-moving groove.

[0010] In a preferred embodiment, a spherical fit is formed between the first free-rotating head and the first free-moving groove, and a spherical fit is formed between the second free-rotating head and the second free-moving groove.

[0011] In a preferred embodiment, the first free-moving slot includes a flared opening and a receiving portion connected to the flared opening. The larger end of the flared opening is larger than the diameter of the first free-rotating head, while the smaller end is smaller than the diameter of the first free-rotating head. The receiving portion has an inner surface adapted to the outer surface of the first free-rotating head.

[0012] In a preferred embodiment, a movable gap is formed between the receiving portion and the first free-rotating head, and the movable gap is filled with non-conductive grease.

[0013] In a preferred embodiment, the lower end of the upper conductive wire is provided with a conductive contact head, and the upper end of the lower conductive wire is provided with a spiral ring. The conductive contact head extends into the spiral ring to form an electrical connection.

[0014] In a preferred embodiment, the spiral ring is made of an elastic material.

[0015] In a preferred embodiment, the upper conductive wire and the lower conductive wire are respectively covered with an upper insulating layer and a lower insulating wire.

[0016] In a preferred embodiment, the upper body and the lower body are connected to each other by anti-rotation pins.

[0017] In a preferred embodiment, an upper anti-rotation groove and a lower anti-rotation groove are respectively provided on the opposite end faces of the upper body and the lower body, and the anti-rotation pin is disposed in the upper anti-rotation groove and the lower anti-rotation groove by means of a spring.

[0018] In a preferred embodiment, the upstream functional section and the downstream functional section are selected from at least two adjacent sections among the pulser section, the pulser drive section, the power supply section, and the measuring probe section.

[0019] The measurement-while-drilling (MWD) apparatus of the present invention employs a specially structured joint mechanism for connection between each pair of the pulser sub, pulser drive sub, power supply sub, and measurement probe sub. This joint mechanism increases the flexibility of the MWD apparatus, ensures that the probe and screw cannot rotate relative to each other, and provides high vibration resistance. The MWD apparatus of the present invention has a simple structure, is easy to manufacture, and can adapt to wellbores with large curvature and short radius, thus meeting the MWD requirements under complex conditions such as sidetracking of older wells. Attached Figure Description

[0020] The invention will now be described with reference to the accompanying drawings. In the drawings:

[0021] Figure 1The diagram schematically shows a wellbore with a large curvature and a short radius, in which a drill collar containing a measurement-while-drilling device according to the invention is run;

[0022] Figure 2 The schematic diagram illustrates the structure of the joint mechanism of the measurement-while-drilling apparatus according to the present invention;

[0023] Figure 3 yes Figure 2 The enlarged view of the joint mechanism shown illustrates the mating structures within the joint mechanism that are capable of relatively free movement.

[0024] In this application, all accompanying drawings are schematic and are used only to illustrate the principles of the invention, and are not drawn to scale. In all drawings, the same reference numerals are used to denote the same parts or structures. Detailed Implementation

[0025] The present invention will now be described with reference to the accompanying drawings. For ease of understanding, in this application, the direction near the wellhead is defined as upper end, upstream, or similar terms, while the direction away from the wellhead is defined as lower end, downstream, or similar terms; simultaneously, the direction along the length of the measurement-while-drilling device is referred to as longitudinal direction, axial direction, or similar terms, while the direction perpendicular to it is referred to as transverse direction, radial direction, or similar terms. It is readily understood that these directional terms are merely for the convenience of describing the present invention and have no limiting effect.

[0026] Figure 1 The diagram schematically illustrates a wellbore with a large curvature and a short radius, in which a drill collar 2 containing a measurement-while-drilling device 500 according to the invention is lowered. Figure 1 As shown, wellbore 1 comprises a section with high curvature and a short radius. Drill collar 2 is connected to screw 4 and drill bit 3 and is lowered into wellbore 1 for drilling operations. A measurement-while-drilling (MWD) device 500 according to the present invention is installed in drill collar 2. This MWD device 500 comprises functional sections connected in sequence, such as pulser section 5, pulser drive section 6, power supply section 7, and measurement probe section 8. Centralizers 9 are installed on pulser drive section 6, power supply section 7, and measurement probe section 8 to ensure they are centered within wellbore 1. Appropriate pulser section 5 and centralizers 9 can be selected according to the dimensions of wellbore 1.

[0027] The functions and structures of the aforementioned components of the measurement-while-drilling device 500, the drill collar 2, the screw 4, and the drill bit 3 are well known to those skilled in the art, and therefore detailed descriptions of them are omitted herein.

[0028] Because of the significant curvature of the wellbore 1, conventional measurement-while-drilling (MWD) instruments, due to their rigidity, are difficult to pass through. Therefore, according to the present invention, the MWD device 500 includes an articulation mechanism 10, which is arranged between each pair of the pulser sub 5, pulser drive sub 6, power supply sub 7, and measuring probe sub 8, thereby connecting the pulser sub 5, pulser drive sub 6, power supply sub 7, and measuring probe sub 8 to form the entire MWD device 500. The articulation mechanism 10 of the MWD device 500 according to the present invention has high flexibility, enabling bending at large angles, thus allowing the MWD device 500 to pass through the wellbore 1 with its large curvature and short radius.

[0029] The following is combined with Figure 2 and 3 The joint mechanism 10 of the measurement-while-drilling device 500 according to the present invention will be introduced, wherein, Figure 2 The schematic diagram shows the overall structure of the joint mechanism 10, while Figure 3 This is a magnified view showing the mating structure in the joint mechanism 10 that is able to move relatively freely.

[0030] like Figure 2 As shown, the joint mechanism 10 includes an upper body 100 and a lower body 200. In the specific embodiment shown, both the upper body 100 and the lower body 200 are formed as generally cylindrical bodies so that they can be easily accommodated in the drill collar 2.

[0031] The upper body 100 is formed as a stepped shaft, including a large shaft portion 101 located upstream and a small shaft portion 102 located downstream. A first connector 160 is formed at the upper end of the large shaft portion 102. The first connector 160 is preferably rigid and is used for fixed connection to the downstream end of a short section (e.g., pulser short section 5, pulser drive short section 6, or power supply short section 7) located upstream of the joint mechanism 10. A first free-rotating head 150 is formed at the end of the small shaft portion 102.

[0032] Furthermore, an upper through-hole 105 extending through the upper body 100 in its axial direction is formed therein, and an upper conductive line 110 is arranged within the upper through-hole 105. According to the present invention, an upper insulating layer 120 is provided on the outer periphery of the upper conductive line 110, and a conductive contact 140 (e.g., ...) is provided at the downstream end of the upper conductive line 110. Figure 3 (As shown). The upper conductive line 110 and the conductive contact 140 form a circuit connection, while the upper insulating layer 120 electrically insulates the upper conductive line 110 from the upper body 100. In addition, the entire upper body 100 serves as a common ground.

[0033] like Figure 3As shown, according to the present invention, the first free-rotating head 150 is formed as a generally spherical structure located at the end of the small shaft portion 102 of the upper body 100. The diameter of the first free-rotating head 150 with this generally spherical structure is larger than the diameter of the small shaft portion 102, such that the first free-rotating head 150 is formed as an outwardly bulging structure at the end of the small shaft portion 102. A recessed second free-moving groove 130 is formed in the first free-rotating head 150. The conductive contact head 140 of the upper conductive wire 110 extends from the through hole 105 and enters the second free-moving groove 130. The bottom (i.e., its upstream portion) of the second free-moving groove 130 is preferably formed as having a generally spherical surface.

[0034] like Figure 2 As shown, the lower body 200 is also formed as a stepped shaft, including a large shaft portion 201 located upstream and a small shaft portion 202 located downstream. Figure 2 In the preferred embodiment shown, the small shaft portion 202 of the lower body 200 forms a second connector 260. The second connector 260 is preferably rigid and is used for fixed connection to the upstream end of a short section (e.g., pulse drive short section 6, power supply short section 7, and measuring probe short section 8) located downstream of the joint mechanism 10.

[0035] A lower through hole 205 extending through the lower body 200 in its axial direction is formed therein, and a lower conductive line 210 is arranged within the lower through hole 205. According to the present invention, a lower insulating layer 220 is provided on the outer periphery of the upper conductive line 210, and a spiral ring 240 (e.g., ...) is provided at the upstream end of the upper conductive line 210. Figure 3 (As shown). The lower conductive line 210 and the spiral ring 240 form a circuit connection, while the lower insulating layer 220 insulates the lower conductive line 210 from the lower body 200 for electrical signals. The entire lower body 200 also serves as a common ground and is short-circuited to the upper body 100, forming a common ground for the entire circuit signals.

[0036] According to the present invention, the large shaft portion 201 of the lower body 200 is made of a slightly elastic material and has a recessed first free-moving groove 230. The first free-moving groove 230 includes a flared opening portion 232 and a receiving portion 235 connected to the flared opening portion 232. The larger end of the flared opening portion 232 is selected to be larger than the diameter of the first free-rotating head 150 to facilitate the insertion of the first free-rotating head 150 into the first free-moving groove 230. The smaller end of the flared opening portion 232 is selected to be smaller than the diameter of the first free-rotating head 150, so that the first free-rotating head 150 cannot be dislodged from the first free-moving groove 230 (specifically, the receiving portion 235) after being inserted into it. The receiving portion 235 of the first free-moving groove 230 is configured to have a shape complementary to the first free-rotating head 150, but slightly larger in size, thereby forming a movable gap 400 between them (e.g., Figure 3 (As shown). Thus, the first free-rotating head 150 can rotate freely within the first free-moving groove 230.

[0037] like Figure 3 As shown, a second freely rotating head 250 extending from the bottom of the first freely movable groove 230 of the lower body 200 is provided, and its free end (i.e., the upstream end) is preferably formed with a generally spherical surface. When the first freely rotating head 150 is inserted into the first freely movable groove 230, the second freely rotating head 250 of the lower body 200 enters the second freely movable groove 130 of the upper body 100. Since both the second freely rotating head 250 and the second freely movable groove 130 have spherical surfaces, the second freely rotating head 250 can rotate freely within the second freely movable groove 130.

[0038] It is readily understood that, according to the present invention, the spherical surface of the second free-rotating head 250 and the spherical surface of the second free-moving groove 130 are configured to be mutually adapted, but slightly smaller in size, so as to facilitate the free rotation of the second free-rotating head 250 within the second free-moving groove 130.

[0039] like Figure 3 As shown, according to the present invention, the spiral ring 240 is disposed at the upstream end of the lower conductive line 210 and is also located in the lower through hole 205. The lower through hole 205 passes through the second free-rotating head 250 of the lower body 200. Thus, when the first free-rotating head 150 is inserted into the first free-moving groove 230, the second free-rotating head 250 of the lower body 200 enters the second free-moving groove 130 of the upper body 100. At this time, the conductive contact head 140 at the end of the upper conductive line 110 enters the spiral ring 240 of the lower body 200, thereby establishing an effective electrical connection between the conductive contact head 140 and the spiral ring 240.

[0040] In a preferred embodiment, the inner diameter of the helical ring 240 is chosen to be slightly larger than the outer diameter of the electrical contact 140, so that the electrical contact 140 can slide relative to the helical ring 240. Additionally, the axial length of the helical ring 240 is chosen to be greater than the axial length of the electrical contact 140, so that the electrical contact 140 can be fully accommodated within the helical ring 240.

[0041] Therefore, according to the present invention, when the upper body 100 of the joint mechanism 10 is connected to the lower body 200, the first free-rotating head 150 of the upper body 100 is inserted into the first free-moving groove 230 of the lower body 200 and can move freely in the first free-moving groove 230; the second free-rotating head 250 of the lower body 200 is inserted into the second free-moving groove 130 of the upper body 100 and can move freely in the second free-moving groove 130; simultaneously, the electrical contact head 140 at the end of the first conductive line 110 of the upper body 100 enters into the spiral ring 240 at the end of the second conductive line 210 of the lower body 200 and can move freely. Through these three free movements, the entire joint mechanism 10 has high flexibility, which makes the measurement-while-drilling device 500 also highly flexible. Thus, the measurement-while-drilling device 500 according to the present invention can smoothly pass through wellbore 1 with large curvature and short radius.

[0042] In a preferred embodiment of the invention, the helical ring 240 is made of an elastic material. In this case, due to the elasticity of the helical ring 240 itself, even under strong vibration, a good electrical connection between the conductive contact head 140 and the helical ring 240 can still be maintained. Thus, the measurement-while-drilling device 500 according to the invention can ensure effective electrical connection between the subs in directional drilling.

[0043] According to a preferred embodiment of the present invention, the movable gap 400 is filled with non-conductive grease, which serves both as lubrication and insulation.

[0044] In addition, such as Figure 2 As shown, in a preferred embodiment of the present invention, the upper body 100 and the lower body 200 are connected to each other by an anti-rotation pin 300, thereby preventing mutual rotation between the upper body 100 and the lower body 200. Specifically, the upper body 100 and the lower body 200 are provided with opposing upper anti-rotation grooves 170 and 270, and the anti-rotation pin 300 is disposed in these two anti-rotation grooves 170 and 270 to connect the upper body 100 and the lower body 200 in an anti-rotation manner.

[0045] Furthermore, preferably, springs 310 are fixedly connected to both anti-rotation grooves 170 and 270, and the two ends of the anti-rotation pin 300 are respectively connected to the two springs 310. The springs 310 are preferably anti-vibration springs. Thus, due to the anti-vibration springs, the upper body 100 and the lower body 200 can be bent at a certain angle relative to each other. Based on the above structural design, the problem of relative angular rotation being impossible in the prior art can be solved, while also reducing the damage caused by vibration to the drilling measurement device during operation.

[0046] It is easy to understand that, in a preferred embodiment of the present invention, the upper body 100 and the lower body 200 are connected to each other by a plurality of anti-rotation pins 300 arranged evenly spaced apart in the circumferential direction.

[0047] The measurement-while-drilling (MWD) device 500 according to the present invention employs a specially structured joint mechanism 10 to connect each pair of the pulser sub 5, pulser drive sub 6, power supply sub 7, and measurement probe sub 8. By using this joint mechanism 10, the flexibility of the MWD device 500 is increased, the probe and screw are prevented from rotating relative to each other, and it exhibits high vibration resistance. The MWD device 500 according to the present invention has a simple structure, is easy to manufacture, and can adapt to wellbores with large curvature and short radius, thus meeting the MWD requirements under complex conditions such as sidetracking of old wells.

[0048] It is readily understood that, in an embodiment of the invention (not shown), the aforementioned articulation mechanism 10 is used for connection only between a portion of adjacent sections of the pulser section 5, the pulser drive section 6, the power supply section 7, and the measuring probe section 8. This achieves a similar technical effect.

[0049] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and does not constitute any limitation to the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to replace some of the technical features therein with equivalents. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of protection of the present invention.

Claims

1. A downhole measurement-while-drilling device (500) includes an upstream functional sub and a downstream functional sub connected to each other via a joint mechanism (10), wherein the joint mechanism (10) includes an upper body (100) fixedly connected to the upstream functional sub and a lower body (200) fixedly connected to the downstream functional sub, and an upper conductor (110) embedded in the upper body (100) is electrically connected to a lower conductor (210) embedded in the lower body (200). in, The lower body (200) includes a recessed first free-moving groove (230), and the upper body (100) includes a protruding first free-rotating head (150). The first free-rotating head (150) extends into the first free-moving groove (230) and can move freely within the first free-moving groove (230). The first free-rotating head (150) includes a recessed second free-moving groove (130), and the first free-moving groove (230) includes a second free-rotating head (250) extending from the bottom surface. The second free-rotating head (250) extends into the second free-moving groove (130) and can move freely within the second free-moving groove (130). A gap-type spherical fit is formed between the first free-rotating head (150) and the first free-moving groove (230), and a gap-type spherical fit is formed between the second free-rotating head (250) and the second free-moving groove (130). The upper body (100) and the lower body (200) are connected to each other by an anti-rotation pin (300). The first free-moving groove (230) includes a flared opening (232) and a receiving portion (235) connected to the flared opening (232). The larger end of the flared opening (232) is larger than the diameter of the first free-rotating head (150), while the smaller end is smaller than the diameter of the first free-rotating head (150). The receiving portion (235) has an inner surface that is adapted to the outer surface of the first free-rotating head (150). An active gap (400) is formed between the receiving portion (235) and the first free-rotating head (150), and the active gap (400) is filled with non-conductive grease. The lower end of the upper conductive wire (110) is provided with a conductive contact head (140), and the upper end of the lower conductive wire (210) is provided with a spiral ring (240). The conductive contact head (140) extends into the spiral ring (240) to form an electrical connection. The upper body (100) and the lower body (200) are respectively provided with an upper anti-rotation groove (170) and a lower anti-rotation groove (270) on their opposite end faces. The anti-rotation pin (300) is provided in the upper anti-rotation groove (170) and the lower anti-rotation groove (270) by means of a spring (310).

2. The downhole measurement-while-drilling device (500) according to claim 1, characterized in that, The spiral ring (240) is made of an elastic material.

3. The downhole measurement-while-drilling device (500) according to claim 1, characterized in that, The upper conductive line (110) and the lower conductive line (210) are respectively covered with an upper insulating layer (120) and a lower insulating line (220).

4. The downhole measurement-while-drilling device (500) according to claim 1, characterized in that, The upstream functional section and the downstream functional section are selected from at least two adjacent sections of the pulser section (5), the pulser drive section (6), the power supply section (7), and the measuring probe section (8).

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