A pressure-increasing and resistance-reducing device for coiled tubing drilling

Abstract

The present invention provides a pressurized resistance-reducing device for continuous tubing drilling, comprising a resistance-reducing unit, the resistance-reducing unit comprising an oscillating element and a jet element connected to the oscillating element; a pressurizing unit, the pressurizing unit comprising a cylinder having an inner cavity connected to the resistance-reducing unit, a piston rod disposed in the inner cavity, a piston sleeved on the piston rod, and a drill assembly connected to the bottom of the pressurizing unit. The jet element is capable of generating a jet so as to cause the fluid flowing through the resistance-reduction unit to oscillate, and the piston rod is capable of axially moving along the cylinder under the action of the pressure difference on both sides of the outer wall of the cylinder, thereby applying a flexible drilling pressure to the bottom drill assembly. The pressurized resistance-reducing device for continuous tubing drilling of the present invention can increase the drilling pressure of continuous tubing drilling while reducing the friction force exerted on the continuous tubing by the well wall.

Description

Technical Field

[0001] The invention relates to the field of oilfield exploitation, and in particular to a pressure-increasing and resistance-reducing device for continuous tubing drilling. Background Art

[0002] Coiled tubing drilling technology is gaining increasing popularity in oil well drilling due to its advantages, including minimal footprint, minimal pollution, and rapid tripping speeds. This is particularly true in China, where most mature oil fields are already in the middle to late stages of development. Coiled tubing drilling can effectively develop difficult-to-use oil and gas resources. Therefore, coiled tubing drilling technology holds a broad prospect for application.

[0003] However, during coiled tubing drilling, the lack of drill collars in the bottom hole assembly limits the injector head's penetration force and prevents it from providing sufficient drilling pressure. Consequently, coiled tubing drilling technology suffers from severe pressure buildup and difficulty extending horizontal sections.

[0004] In addition, due to its non-rotating, light weight and low rigidity, the coiled tubing can easily cause the tubing string to become unstable and spirally locked when it is subjected to friction from the well wall, making it difficult to apply coiled tubing drilling technology to deep wells. Summary of the Invention

[0005] To address the above technical issues, the present invention provides a pressure-increasing and drag-reducing device for coiled tubing drilling. The pressure-increasing and drag-reducing device for coiled tubing drilling of the present invention can increase drilling pressure during coiled tubing drilling while reducing the friction force exerted on the coiled tubing by the wellbore wall.

[0006] According to the present invention, a pressurized resistance-reducing device for coiled tubing drilling is provided, comprising: a resistance-reducing unit, the resistance-reducing unit including an oscillating element and a jet element connected to the oscillating element; a pressurizing unit, the pressurizing unit including a cylinder having an inner cavity connected to the resistance-reduction unit, a piston rod disposed in the inner cavity and a piston sleeved on the piston rod; and a drill tool assembly connected to the bottom of the pressurizing unit.

[0007] The jet element can generate a jet to cause the fluid flowing through the resistance reduction unit to oscillate, and the piston rod can move axially along the cylinder under the action of the pressure difference on both sides of the outer wall of the cylinder, thereby applying flexible bit pressure to the bottom drilling tool assembly.

[0008] In a preferred embodiment, the jet element is provided with an annular first vortex chamber and a second vortex chamber, as well as a reversing flow channel and a feedback flow channel respectively connecting the first vortex chamber and the second vortex chamber.

[0009] In a preferred embodiment, the reversing flow channel is configured to be substantially V-shaped, and the feedback flow channel is arranged along a common tangential direction of the first vortex chamber and the second vortex chamber.

[0010] In a preferred embodiment, the piston rod is constructed in a tubular shape, a liquid cavity is formed between the piston rod and the inner wall of the cylinder, and the piston is disposed in the liquid cavity.

[0011] In a preferred embodiment, at least one breathing hole communicating with the liquid cavity is further provided on the outer wall of the cylinder.

[0012] In a preferred embodiment, a scraping ring is provided on the outer wall of the piston rod, and the scraping ring is sleeved on the groove of the outer wall of the piston rod.

[0013] In a preferred embodiment, a spline joint connected to the bottom drilling tool is further provided at the end of the cylinder away from the resistance reduction unit, and the spline joint includes a spline shaft and a spline cylinder.

[0014] In a preferred embodiment, an anti-drop half ring is sleeved on the spline shaft.

[0015] In a preferred embodiment, a plurality of pressurizing units are provided in the cylinder.

[0016] In a preferred embodiment, the bottom of the piston rod has a liquid groove, thereby allowing the drilling fluid flowing through the piston rod to enter between the piston rod and the spline shaft, thereby pushing the spline shaft and the piston rod to move together. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The present invention will be described below with reference to the accompanying drawings.

[0018] Figure 1 A schematic diagram of a pressurized resistance-reducing device for coiled tubing drilling according to one embodiment of the present invention is shown.

[0019] Figure 2 for Figure 1 Schematic diagram of the jet element of the pressurized drag reduction device for coiled tubing drilling.

[0020] Figure 3 A schematic diagram of a cylinder in a pressurizing unit according to the present invention is shown.

[0021] Figure 4 for Figure 1 Schematic diagram of the piston rod of the pressurized resistance reduction device for coiled tubing drilling.

[0022] In this application, all drawings are schematic drawings, which are only used to illustrate the principles of the present invention and are not drawn to scale. DETAILED DESCRIPTION

[0023] The present invention will be described below with reference to the accompanying drawings.

[0024] Figure 1 FIG. 1 shows a pressure-reducing resistance reducing device 100 for coiled tubing drilling according to an embodiment of the present invention. Figure 1 As shown, the pressurized drag reduction device 100 for coiled tubing drilling comprises a drag reduction unit 1 connected to a drill string (not shown). The drag reduction unit 1 comprises an oscillating element 10 and a fluidic element 20 inserted into the oscillating element 10. The fluidic element 20 generates a periodically varying jet of high-pressure fluid flowing through the fluidic element 20, thereby driving the oscillating element 10 to oscillate. This causes the oscillating element 10 to vibrate periodically in the axial direction, thereby driving the downhole drill string (not shown) to vibrate in the axial direction, thereby reducing friction between the drill string and the wellbore wall and achieving the effect of reducing friction and drag.

[0025] Figure 2 for Figure 1 FIG. 1 is a schematic diagram of a jet element 20 of a pressure resistance reducing device 100 for coiled tubing drilling. Figure 2 As shown, a first annular vortex chamber 22 and a second annular vortex chamber 24 are provided within the flow element 20. A liquid inlet 225 and a liquid outlet 245 are provided in the first and second vortex chambers 22, 24, respectively. A reversing flow channel 25 and a feedback flow channel 26 are provided between the first and second vortex chambers 22, 24, respectively connecting the first and second vortex chambers 22, 24.

[0026] like Figure 2 As shown, the reversing flow channel 25 is configured in a substantially V-shape, comprising a first flow channel 251 communicating with the first vortex chamber 22, and a second flow channel 252 and a third flow channel 253 communicating with the first vortex chamber 24. Two feedback flow channels 26 are provided, one arranged along a common tangent direction of the first vortex chamber 22 and the other arranged along a common tangent direction of the second vortex chamber 24.

[0027] After the high-pressure liquid leaves the oscillating element 10, it will pass through the liquid inlet 225 and reach the jet element 20, and form a jet at the liquid inlet 225. The jet will then pass through the first flow channel 251 and the second flow channel 252 respectively and reach the second vortex chamber 24. In this process, since the high-pressure fluid is turbulent and the flow is unstable, the flow rate entering the second flow channel 252 and the third flow channel 253 is different, resulting in the two fluids passing through the second flow channel 252 and the third flow channel 253 respectively impacting each other and flowing out in the second vortex chamber 24. According to the wall attachment effect, the jet will eventually flow from only one of the first flow channel 251 or the second flow channel 252 to the second vortex chamber 24, and form a vortex in the second vortex chamber 24.

[0028] As the vortex in the second vortex chamber 24 grows larger, the fluid flow rate and flow velocity in the feedback flow channel 26 increase accordingly. When the vortex in the second vortex chamber 24 grows to a certain critical value, the fluid in the feedback flow channel 26 impacts the fluid in the second flow channel 252 or the third flow channel 253, causing it to reverse direction, until the vortex in the second vortex chamber 24 is disrupted and gradually dissipates, forming a reverse vortex flow. This periodic switching can produce an oscillation effect, causing the oscillating element 10 to generate a periodically changing axial force, thereby driving the oscillating element 10 to produce periodic vibrations along the axial direction.

[0029] like Figure 1 As shown, the pressurized resistance reduction device 100 for continuous tubing drilling also includes a pressurizing unit 2. The pressurizing unit 2 is arranged downstream of the resistance reduction unit 1 and can receive the periodically switched high-pressure fluid flowing out of the resistance reduction unit 1. The pressurizing unit 2 is connected to a drill bit assembly (not shown) away from the bottom of the resistance reduction unit 1. In the present invention, the oscillation mechanism 10 can cause the high-pressure fluid in the well to produce an oscillating effect, so that the high-pressure fluid with an oscillating effect acts on the pressurizing unit 2. In this way, the high and low pressure differences formed between the high-pressure fluid with an oscillating effect and the bottom drill bit assembly will act on the pressurizing unit 2, so that the pressurizing unit 2 applies a flexible drilling pressure to the bottom drill bit assembly.

[0030] like Figure 1 As shown, the pressurizing unit 2 includes a cylinder 30 having an inner cavity 35. The cylinder 30 is connected to the resistance reduction unit 1 via a joint 31, allowing fluid to flow into the inner cavity 35 after passing through the resistance reduction unit 1. A piston rod 32 is also disposed within the cylinder 30, with a piston 321 sleeved on its outer wall. The piston rod 32 is capable of moving axially along the cylinder 30 under the influence of the internal and external pressure differential exerted on the end surface of the piston 321. Furthermore, the piston rod 32 is tubular in shape and defines a fluid flow channel 351 therein, allowing fluid entering the inner cavity 35 to flow out of the cylinder 30 through the channel 351.

[0031] A liquid chamber 31 is formed between the piston rod 32 and the cylinder barrel 30 disposed outside the piston rod 32. The liquid chamber 31 can provide a temporary storage space for the drilling fluid.

[0032] It is easy to understand that when the fluid pressure in the inner cavity 35 is greater than the fluid pressure in the space 38 outside the cylinder 30, this pressure difference will act on the end faces on both sides of the piston 321, thereby pushing the piston rod 32 to move away from the jet element 20.

[0033] Figure 3 Schematic diagram of the cylinder 30 in the pressurizing unit 2 according to the present invention is shown. Figure 3 As shown, the cylinder 30 is provided with two breathing holes 60 that communicate with the liquid chamber 31. These two breathing holes 60 are preferably radially symmetrically distributed to ensure communication between the liquid chamber 31 and the external annulus. Thus, as the piston 321 and piston rod 32 assembly freely reciprocates axially within the cylinder 30, downhole fluid can be repeatedly drawn in and out through the liquid chamber 31.

[0034] During oil well drilling, drilling fluid first passes through the drill string to the drill bit (not shown) at the bottom of the well. It then passes through the drill bit into the space between the drill string and the wellbore wall, and then returns to the wellhead through the space between the drill string and the wellbore wall, completing the cycle. During this cycle, due to the throttling pressure differential between the drill bit and the bottom hole motor, the pressure of the drilling fluid returning from the space 38 between the drill string and the wellbore wall to the wellhead is always lower than the pressure of the drilling fluid within the drill string.

[0035] Therefore, when the pressurized drag-reducing device 100 for coiled tubing drilling of the present invention is installed on a drill string and participates in drilling fluid circulation, the fluid pressure outside the cylinder 30 is always lower than the fluid pressure within the inner chamber 35. This pressure differential causes the piston rod 32 to move away from the fluidic element 20, transmitting this pressure to the drill assembly below.

[0036] Figure 4 for Figure 1 Schematic diagram of the piston rod 32 of the pressure resistance reduction device 100 for continuous tubing drilling. Figure 4 As shown, a slot 42 is provided on the outer wall of the piston rod 32. This slot is used to fit a scraper ring. The scraper ring is configured as a circular ring that protrudes from the slot 42 and abuts against the inner wall of the cylinder 30. As a result, when the piston rod 32 moves axially along the cylinder 30, the scraper ring 47 cleans the inner wall of the cylinder 30, preventing drilling fluid or other solid impurities from remaining on the inner wall of the cylinder 30.

[0037] like Figure 1As shown, a spline joint 50 is provided at the end of the piston rod 32 distal from the oscillating element 10. The pressure-enhancing drag-reducing device 100 is connected to the drill string via the spline joint 50. Specifically, the spline joint 50 comprises a spline shaft 52 and a spline cylinder 54 that are sleeved together. The spline joint 50 ensures that the pressure-enhancing drag-reducing device 100 for coiled tubing drilling according to the present invention rotates synchronously with the drill string during downhole drilling.

[0038] At the same time, an anti-drop half ring is provided on the outer wall of the spline shaft 52. The anti-drop half ring 56 can be embedded in a slot (not shown) provided on the spline shaft, thereby preventing the spline shaft 52 from slipping and falling into the well bottom, causing an underground accident.

[0039] As will be readily understood, the present invention utilizes the piston rods 32 and spline shaft 52 to achieve two-stage pressurization. This arrangement further enhances the pressurization efficiency of the coiled tubing drilling resistance reduction device 100 of the present invention. Furthermore, a fluid flow groove 322 is provided at the bottom of the piston rods 32. Due to the presence of the fluid flow groove 322, drilling fluid flowing through the first set of piston rods 32 enters the end of the spline shaft 52, effectively resolving the issue of obstructed drilling fluid flow.

[0040] It should be noted that the staff can also set multiple sets of piston rods 32 according to the actual working conditions on site and the overall tensile and torsional strength of the tool to determine the actual pressurization levels, which is not limited here.

[0041] The following briefly describes the working process of the pressure-increasing and resistance-reducing device 100 for coiled tubing drilling according to the present invention.

[0042] The pressure-reducing drag reduction device 100 for coiled tubing drilling of the present invention is designed to be connected to a drill string and lowered into an oil and gas well along with the drill string. During drilling, the drag reduction unit 1 generates periodic hydraulic oscillations, causing the pressure-reducing drag reduction device 100 to vibrate periodically along the axial direction, driving the drill string downhole in a periodic manner. This reduces friction between the drill string and the wellbore wall, achieving the desired effect of reducing friction and drag.

[0043] At the same time, during the circulation of the drilling fluid, since the pressure of the drilling fluid in the cylinder 30 is always higher than the pressure of the drilling fluid between the cylinder 30 and the well wall, a pressure difference is generated on the radial sides of the cylinder 30, pushing the piston rod 32 and the piston 321 on the piston rod 32 to move away from the oscillating element 10, thereby transmitting the pressure to the drill tool assembly on the side of the piston rod 32 away from the oscillating element 10, thereby generating a pressurizing effect.

[0044] 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 pressure-increasing and drag-reducing device (100) for coiled tubing drilling, comprising: A resistance reduction unit (1), comprising an oscillating element (10) and a fluidic element (20) connected to the oscillating element; a pressurizing unit (2) arranged downstream of the resistance reducing unit, the pressurizing unit comprising a cylinder (30) having an inner cavity (35) connected to the resistance reducing unit, the cylinder being connected to the resistance reducing unit via a joint, a piston rod (32) being provided in the inner cavity, a piston (321) being sleeved on the piston rod, the piston rod being tubular, a liquid cavity (31) being formed between the piston rod and the inner wall of the cylinder, the piston being provided in the liquid cavity, and at least one breathing hole (60) being provided on the outer wall of the cylinder for communicating with the liquid cavity, connecting the liquid cavity with the space (38) outside the cylinder, and when the fluid pressure in the inner cavity is greater than the fluid pressure in the space, the pressure difference acts on the end faces on both sides of the piston, thereby pushing the piston rod to move in a direction away from the jet element; and, A drilling assembly connected to the bottom of the pressurizing unit, The jet element can generate a jet to cause the fluid flowing through the resistance reduction unit to oscillate, and the piston rod can move axially along the cylinder under the action of the pressure difference on both sides of the outer wall of the cylinder, thereby applying flexible bit pressure to the bottom drilling tool assembly.

2. The pressure-reducing resistance device (100) for coiled tubing drilling according to claim 1, characterized in that: The jet element is provided with an annular first vortex chamber (22) and a second vortex chamber (24), as well as a reversing flow channel (25) and a feedback flow channel (26) respectively communicating with the first vortex chamber and the second vortex chamber.

3. The pressure-reducing resistance device (100) for coiled tubing drilling according to claim 2, characterized in that: The reversing flow channel is configured to be substantially V-shaped, and the feedback flow channel is arranged along a common tangential direction of the first vortex chamber and the second vortex chamber.

4. The pressure-reducing resistance device (100) for coiled tubing drilling according to claim 1, characterized in that: A scraping ring (47) is provided on the outer wall of the piston rod, and the scraping ring is sleeved on the groove (42) of the outer wall of the piston rod.

5. The pressure-increasing and resistance-reducing device (100) for coiled tubing drilling according to any one of claims 1 to 4, characterized in that: A spline joint connected to the bottom drilling tool is further provided at the end of the cylinder away from the resistance reduction unit. The spline joint includes a spline shaft and a spline cylinder.

6. The pressure-increasing and resistance-reducing device (100) for coiled tubing drilling according to claim 5, characterized in that: An anti-drop half ring is also sleeved on the spline shaft.

7. The pressure-increasing and resistance-reducing device (100) for coiled tubing drilling according to any one of claims 1 to 4, characterized in that: A plurality of pressurizing units are arranged in the cylinder.

8. The pressure-reducing resistance device (100) for coiled tubing drilling according to any one of claims 1 to 4, characterized in that: The bottom of the piston rod is provided with a liquid groove, thereby allowing the drilling fluid flowing through the piston rod to enter between the piston rod and the spline shaft, thereby pushing the spline shaft and the piston rod to move together.

Images