A downhole flushing and hook-making integrated retrieval tool and retrieval method

Abstract

This invention provides an integrated downhole flushing and hook-making retrieval tool and method. The retrieval tool includes a hook-making section and a flushing section, which are connected. The hook-making section has a hook-making part on its inner wall, which can hook the outer wall of the fish that has entered the hook-making section, so as to tightly connect the retrieval tool with the fish. The flushing section has a flushing part on its inner wall, which has several axially penetrating flushing holes. The fish in the flushing section can form an annulus with the inner wall of the flushing section. Drilling fluid can flush the rock cuttings below the fish along the annulus through the flushing holes to release the rock cuttings from the fish. The drilling fluid circulation can be established through the annulus between the retrieval tool and the fish and the flushing holes to circulate and flush the bottom of the well, gradually clearing the rock cuttings from the fish and the well wall, thereby significantly reducing the tensile force and rotational torque required to release the fish after hook-making.

Description

Technical Field

[0001] This invention relates to the field of downhole object retrieval technology in oil and gas well drilling, specifically to an integrated downhole flushing and hook-making retrieval tool and method. Background Technology

[0002] During oil and gas drilling, downhole drilling assemblies operate under conditions of drilling pressure, torque, and strong axial, radial, circumferential, and combined vibration loads. Due to material defects such as porosity and microcracks in the drilling tools, or stress concentration caused by design flaws, the drilling tools may suffer fatigue damage when operating for a long time. Especially when encountering complex downhole situations such as wellbore collapse, once the drilling tools break and fall into the well, the area around the fallen fish is often filled with rock cuttings and stuck, making retrieval extremely difficult.

[0003] Currently, the only methods for retrieving such fallen fish are to use a male or female cone to create a snag on the upper part of the fish, and then use pulling, pressing, or twisting methods to retrieve it. However, the following problems exist, preventing the fish from being retrieved from the well:

[0004] (1) When conventional fishing tools are a certain distance from the top of the fish, if a large-volume circulation is used to flush the fallen fish, the drilling fluid will cause severe erosion of the well wall and form a large belly, which will cause the well wall to collapse further and bury the fallen fish, making it impossible to carry out hook-making and fishing operations.

[0005] (2) Because the area around the fish is filled with rock cuttings and stuck, when the male or female cone is used to make the connection, it is impossible to establish drilling fluid circulation to clean the rock cuttings and bring them out of the wellhead, thus reducing the stuck state of the fish. Usually, it is impossible to provide enough tension and torque to force the fish out of the stuck state, and the fish cannot be retrieved from the well.

[0006] In summary, existing retrieval tools and methods have a very low success rate when fish are trapped and stuck in the well by rock debris. Breakthroughs in the structure and methods of retrieval tools are urgently needed. Summary of the Invention

[0007] The purpose of this invention is to address at least one of the aforementioned shortcomings of the existing technology. For example, one objective of this invention is to provide an integrated downhole flushing and hook-making retrieval tool and method. This solves the technical problems in the existing technology, such as fish getting stuck in rock cuttings, low retrieval success rate, and high difficulty.

[0008] To achieve the above objectives, the present invention provides a downhole flushing and hook-making integrated fishing tool. The fishing tool may include a hook-making section and a flushing section. The hook-making section is connected to the flushing section. The inner wall of the hook-making section is provided with a hook-making part, which can hook the outer wall of the fish that has fallen into the hook-making section, so as to tightly connect the fishing tool with the fish. The inner wall of the flushing section is provided with a flushing part, which has a plurality of axially penetrating flushing holes. The fish in the flushing section can form an annulus with the inner wall of the flushing section. Drilling fluid can flush the rock cuttings below the fish through the flushing holes along the annulus to release the rock cuttings from the fish.

[0009] Alternatively, the retrieval tool may further include a guide section disposed at the lower end of the rinsing section, the guide section being capable of scraping away rock debris around the fallen fish to guide the fallen fish into the retrieval tool.

[0010] Alternatively, the snap-fit ​​part can be a high-strength female cone retrieval thread, which is used to snap the snap-fit ​​at the upper end of the fallen fish and provide sufficient pulling force to retrieve the fallen fish out of the well.

[0011] Alternatively, the rinsing part may protrude radially inward along the rinsing section, the inner diameter of the rinsing section being larger than the inner diameter of the rinsing part, and the difference between the inner diameter of the rinsing section and the inner diameter of the rinsing part being 2 to 5 cm.

[0012] Alternatively, the number of flushing holes may be 6 to 12, and the flushing holes are distributed circumferentially in the flushing section.

[0013] Alternatively, the inner diameter of the rinsing section can be 5-12 mm larger than the outer diameter of the fish, so that the fish can pass through the rinsing section and enter the rinsing section and the buckling section.

[0014] Alternatively, the guide portion may be an annular structure with an inclined notch, and the guide portion may be circumferentially rotated to scrape rock debris and catch the fallen fish into the retrieval tool.

[0015] Optionally, a female buckle can be provided at the upper end of the inner wall of the buckling section. The female buckle can cooperate with the male buckle of the upper drill bit of the retrieval tool to fix the retrieval tool to the upper drill bit.

[0016] Optionally, the distance between the flushing section and the lower end of the retrieval tool can be 3 to 8 cm, which can increase the drilling fluid velocity and prevent the drilling fluid from eroding the well wall.

[0017] Another aspect of the present invention provides a method for retrieving fish from a downhole well. The method can employ the downhole flushing and hook-making integrated retrieval tool described above. The retrieval method may include: assessing the degree to which the fish is stuck by downhole cuttings before retrieval; determining the structure and size of the fish, and determining the size of the retrieval tool based on the size of the fish; assembling the retrieval tool and drill string into the downhole drill string; when the distance between the retrieval tool and the fish is a first distance, starting the pump to circulate and flush the bottom of the well, and then continuing to lower the retrieval tool to a second distance at a first speed; rotating the retrieval tool at a first rotational speed to reduce the circulation rate and slow down the drilling. The retrieval tool is lowered to the second speed, and relevant parameters are recorded. When the riser pressure reaches the preset pressure difference range, the descent of the drill string is stopped, and the parameter changes are used to determine whether the retrieval tool has caught the fish. After the retrieval tool catches the fish, circulation and flushing are maintained to flush away the rock cuttings at the bottom of the well and bring them out of the wellhead by the drilling fluid. After the rock cuttings are cleaned up, circulation and rotation of the retrieval tool are stopped. The retrieval tool is then lowered, and a preset torque is applied to the fish at the second speed to create a connection, thus connecting the retrieval tool with the fish. The retrieval tool and the fish are then pulled up to the wellhead, completing the retrieval.

[0018] Alternatively, the size of the fish may include the outer diameter of the fish. The distance L1 from the top of the fallen fish to the stabilizer or the point where the outer diameter increases, and the dimensions of the retrieval tool include the inner diameter of the buckle. The inner diameter of the flushing section The inner diameter of the flushing section The distance L2 between the lower end of the retrieval tool and the buckling part; wherein, L2 = L1 - (7 ~ 10 cm).

[0019] Optionally, the first distance can be 7-10m, the first speed can be 7-12min / m, the second distance can be 2-3m, the first rotation speed can be 5-10r / min, the second speed can be 15-20min / m, the preset pressure difference range can be 0.5-1MPa, the second rotation speed can be 5r / min, and the preset torque can be less than or equal to 55000N·m.

[0020] Alternatively, the recorded relevant parameters may include one or more of the following parameters: recorded rotational torque T1, riser pressure P1, and weight of the weight indicator HL1.

[0021] Alternatively, determining whether the retrieval tool has been fitted onto the fallen fish may include determining whether the suspended weight and rotational torque of the retrieval tool have increased. If they have increased, it indicates that the lower end of the retrieval tool has begun to fit onto the top of the fallen fish.

[0022] Optionally, the time for maintaining the circulation and rinsing after the fishing tool is inserted into the fish can be 3 to 5 hours; if the pressure in the riser suddenly drops by more than 2 MPa during the circulation and rinsing process after the fishing tool is inserted into the fish, the circulation flow rate is increased and the circulation and rinsing continues for 1 to 2 hours; if the pressure in the riser does not drop or drops by less than 2 MPa during the circulation and rinsing process after the fishing tool is inserted into the fish, the lowering is stopped when the top of the fish is 3 to 5 cm away from the hook-making part, and the rinsing continues for 2 to 3 hours.

[0023] Alternatively, the retrieval method may further include, after the retrieval tool is combined with the fallen fish, if the pump can be turned on, continuing the circulation for 1 to 2 hours; if the pump cannot be turned on, performing a release operation until the fallen fish is released.

[0024] Compared with the prior art, the beneficial effects of the present invention include at least one of the following:

[0025] (1) The inclined notch ring structure at the bottom of the retrieval tool of the present invention can effectively scrape the rock debris between the fallen fish and the well wall when rotated clockwise, so as to smoothly put the fallen fish into the retrieval tool, effectively solving the technical problem that the fallen fish is difficult to enter the retrieval tool, and also effectively improving the quality of the hook at the top of the fallen fish, which can provide more than 100 tons of pulling force for the retrieval tool.

[0026] (2) The inner diameter of the annular protrusion structure of the retrieval tool is slightly larger than the outer diameter of the fish. After being used with the fish, drilling fluid circulation can be established through the hole nozzle of the annular structure. At the same time, the hole nozzle guides the drilling fluid jet to spray towards the rock cuttings in the annulus between the fish and the well wall. After being transported upward through the annular circulation, the fish is gradually put into the interior of the retrieval tool by rotating and pressing it down. At the same time, due to the flow restriction effect of the retrieval tool, the erosion effect of the drilling fluid jet on the well wall is greatly reduced, avoiding the formation of a large belly that could lead to further collapse.

[0027] (3) The drilling fluid circulation can be established between the fishing tool of the present invention and the annulus and flushing hole to circulate and flush the bottom of the well, gradually cleaning the rock cuttings on the bottom of the well and the bottom wall, thereby greatly reducing the tension and rotation torque required to release the bottom of the fish after the hook is made, and there is a certain probability that after the rock cuttings on the bottom of the fish and the bottom wall are cleaned, the blockage in the lower part of the water eye of the bottom fish can be cleared under the action of the internal pressure difference of the bottom fish, thereby establishing a normal circulation from the water eye to the annulus.

[0028] (4) Before the application of the salvage tool and salvage method of the present invention, the conventional mother cone could not be used to untangle and salvage under a pulling force of 190 tons. After thorough rinsing with the salvage tool of the present invention, the salvage was successfully achieved with only 28 tons of pulling force, which greatly reduced the pulling force required for salvage. Attached Figure Description

[0029] The above and other objects and / or features of the present invention will become clearer from the following description taken in conjunction with the accompanying drawings, in which:

[0030] Figure 1 A structural diagram of an integrated downhole flushing and hook-making salvage tool according to an exemplary embodiment of the present invention is shown.

[0031] Figure 2 It shows Figure 1 Cross-sectional view at point AA.

[0032] Figure 3 The diagram shows a fish trapped in rock debris after falling into a well.

[0033] Explanation of reference numerals in the attached figures:

[0034] 1. Buckle-making section, 11. Buckle-making part, 12. Female buckle, 2. Flushing section, 21. Flushing part, 211. Flushing hole, 3. Guide part, 4. Fish falling, 5. Rock debris. Detailed Implementation

[0035] In the following sections, the integrated downhole flushing and hook-making retrieval tool and retrieval method of the present invention will be described in detail with reference to exemplary embodiments.

[0036] In the description of this application, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0037] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0038] In the description of this application, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0039] In related technologies, when the retrieval tool is a certain distance from the top of the fish, if a large-volume circulation is used to flush the fallen fish, the drilling fluid will cause severe erosion of the well wall and form a large belly, leading to further collapse of the well wall and burying the fallen fish, making it impossible to carry out the hooking and retrieval operation. In addition, because the area around the fallen fish is filled with rock cuttings and stuck, when the male or female cone is used for hooking and connection, it is usually impossible to establish drilling fluid circulation to clean and carry the rock cuttings out of the wellhead to reduce the stuck state of the fallen fish. It is also usually impossible to provide enough tension and torque to force the fallen fish out of the stuck state, making it impossible to retrieve the fallen fish from the well.

[0040] Based on this, the present invention provides an integrated downhole flushing and hook-making retrieval tool and retrieval method. The retrieval tool includes a hook-making section and a flushing section, which are connected. The inner wall of the hook-making section is provided with a hook-making part, which can hook the outer wall of the fish that has fallen into the hook-making section, so as to tightly connect the retrieval tool with the fish. The inner wall of the flushing section is provided with a flushing part, which has several axially penetrating flushing holes. The fish in the flushing section can form an annulus with the inner wall of the flushing section. Drilling fluid can flush the rock cuttings below the fish through the flushing holes along the annulus to remove the rock cuttings from the fish.

[0041] The inclined notch annular structure at the bottom of the retrieval tool of this invention can effectively scrape away rock debris between the fallen fish and the well wall when rotated clockwise, thus smoothly fitting the fallen fish into the retrieval tool. This effectively solves the technical problem of the fallen fish being difficult to enter the retrieval tool, and also effectively improves the quality of the hook-on at the top of the fallen fish, providing the retrieval tool with a pulling force of over 100 tons. The inner diameter of the annular protrusion structure of the retrieval tool is slightly larger than the outer diameter of the fallen fish. After being fitted with the fallen fish, drilling fluid circulation can be established through the perforated nozzle of the annular structure. At the same time, the perforated nozzle guides the drilling fluid jet towards the rock debris in the annulus between the fallen fish and the well wall. After circulating upwards through the annulus, the fallen fish is gradually fitted into the retrieval tool by rotating and pressing it down. At the same time, due to the flow restriction effect of the retrieval tool, the drilling fluid jet has a certain impact on the well. The erosion effect on the well wall is greatly reduced, avoiding the formation of a large "belly" that could lead to further collapse. The drilling fluid circulation between the retrieval tool and the wellbore through the annulus and flushing holes can be used to circulate and flush the bottom of the well, gradually clearing away rock debris from the wellbore and the fish. This significantly reduces the tensile force and rotational torque required to release the fish after the hook is created. Furthermore, there is a certain probability that after clearing the rock debris from the fish and the wellbore, the internal pressure difference of the fish can clear the blockage in the lower part of the water hole, thus establishing a normal circulation from the water hole to the annulus. Before the application of the retrieval tool and method of this invention, conventional mother cones could not release the fish even with a pulling force of 190 tons. After thorough flushing with the retrieval tool of this invention, retrieval was successfully achieved with only 28 tons of pulling force, greatly reducing the pulling force required for retrieval.

[0042] Exemplary Example 1

[0043] This exemplary embodiment provides an integrated downhole flushing and hook-making salvage tool.

[0044] Figure 1 A structural diagram of an integrated downhole flushing and hook-making retrieval tool according to an exemplary embodiment of the present invention is shown; Figure 2 It shows Figure 1 Cross-sectional view at point AA; Figure 3 The diagram shows a fish trapped in rock debris after falling into a well.

[0045] like Figures 1 to 3 As shown in the exemplary embodiment, the downhole flushing and hook-making integrated retrieval tool may include a hook-making section 1 and a flushing section 2, wherein the hook-making section 1 and the flushing section 2 can be integrally formed and connected, and the inner cavity of the hook-making section 1 can communicate with the inner cavity of the flushing section 2; in the working state of the downhole retrieval tool, the hook-making section 1 is located at the upper end of the flushing section 2; a hook-making part 11 is provided on the inner wall of the hook-making section 1. When the top of the fish 4 extends into the hook-making section 1, the hook-making part 11 can hook the outer wall of the fish 4, thereby tightly connecting the fish 4 with the retrieval tool. The retrieval tool can apply sufficient pulling force to the fish 4 so that the fish 4 can be retrieved from the well together with the retrieval tool.

[0046] The inner wall of the flushing section 2 is provided with a flushing part 21, and the flushing part 21 is provided with multiple flushing holes 211. Each flushing hole 211 can pass through the flushing part 21 axially. When the fish 4 passes through the flushing part 21 and enters the flushing section 2, the outer wall of the fish 4 can form an annulus with the inner wall of the flushing section 2. That is to say, the inner diameter of the flushing section 2 is larger than the outer diameter of the fish 4. Drilling fluid can enter the annulus between the flushing section 2 and the fish 4 from the inner cavity of the buckling section 1, and then spray out from the lower end of the fishing tool along the flushing holes 211 on the flushing part 21, thereby flushing the rock cuttings 5 ​​around the fish 4 at the bottom of the well, thereby relieving the obstruction of the fish 4 by the rock cuttings 5, which is conducive to the fishing operation.

[0047] In this embodiment, the retrieval tool may further include a guide part 3, which may be located at the lower end of the flushing section 2, that is, at the lowest end of the retrieval tool. Usually, the posture of a fish falling to the bottom of the well is not conducive to fitting the top of the fish into the retrieval tool. For example, if the fish is lying horizontally and is stuck by rock cuttings 5 ​​at the bottom of the well, its posture is relatively firm. It is very difficult to simply lower the retrieval tool along the well shaft to fit the fish in. At this time, the guide part 3 of the retrieval tool can be used to scrape the rock cuttings 5 ​​around the fish to reduce the stuck effect of the rock cuttings 5 ​​on the fish. The guide part 3 can also be used to adjust the posture of the fish from a horizontal to a vertical position, and then guide the top of the fish into the retrieval tool, thereby realizing the fitting of the retrieval tool into the fish.

[0048] Alternatively, the guide part 3 can be a ring structure with an inclined notch. When the retrieval tool drives the guide part 3 to rotate circumferentially, the notch structure on the guide part 3 can scrape the rock debris around the fallen fish. Specifically, the direction of circumferential rotation can be clockwise or counterclockwise. The specific rotation direction can be determined according to the opening direction of the inclined notch on the guide part 3. As long as the inclined notch of the guide part 3 can scrape the rock debris during the rotation, the rock debris can be scraped away, which can reduce or even release the holding effect on the fallen fish, making it easier to adjust the fallen fish to a vertical position and thus make it easier to be put into the retrieval tool.

[0049] In this embodiment, the snap-fit ​​part 11 can be a high-strength female cone retrieval thread. Specifically, the high-strength female cone retrieval thread can be set at the lower end of the inner wall of the snap-fit ​​section 1, close to the flushing section 2. When the fish 4 that has entered the retrieval tool passes through the flushing section 2 and reaches the snap-fit ​​section 1, the top of the fish 4 can be snapped by pressing down on the retrieval tool and applying sufficient torque to the retrieval tool. At the same time, the fish can be tightly inserted into the snap-fit ​​section 1, so that the retrieval tool and the fish 4 are tightly connected. When the retrieval tool applies a sufficiently large upward pulling force to the fish 4, it can also ensure that the fish is lifted while preventing it from falling out of the retrieval tool and causing retrieval failure. However, the present invention is not limited to this. The structure of the snap-fit ​​part 11 is not limited to the high-strength female cone retrieval thread. As long as it can provide sufficient clamping force to lift the fish and prevent it from falling out, the present invention does not make specific limitations.

[0050] Optionally, the flushing section 21 is disposed on the inner wall of the flushing section 2. The flushing section 21 can protrude inward along the radial direction of the flushing section 2. That is, the inner diameter of the flushing section 2 can be larger than the inner diameter of the flushing section 21. The annular space formed between the fish 4 after it passes through the flushing section 21 and enters the flushing section 2 and the inner wall of the flushing section 2 is thus formed. Specifically, the difference between the inner diameter of the flushing section 2 and the inner diameter of the flushing section 21 can be 2 to 5 cm. Therefore, the annular space between the fish 4 in the flushing section 2 and the inner wall of the flushing section 2 can reach a sufficiently large space. When the drilling fluid entering the annular space flows into the area below the fishing tool through the flushing hole 211 on the flushing section 21, the sufficient annular space can provide fluid buffer for the flushing hole 211. However, the present invention is not limited to this. The range of the difference between the inner diameter of the flushing section 2 and the inner diameter of the flushing section 21 can also be arbitrarily selected according to the actual operation needs. It is not limited to the range of 2 to 5 cm defined in this embodiment. The present invention does not make specific limitations in this regard.

[0051] Alternatively, the inner diameter of the flushing section 21 can be slightly larger than the outer diameter of the fish 4. Specifically, the difference between the inner diameter of the flushing section 21 and the outer diameter of the fish 4 can be 5 to 12 mm. Within this range, the fish 4 can be inserted into the flushing section 21. When the drilling fluid enters the annulus between the fish 4 and the inner wall of the flushing section 2, the drilling fluid can maintain sufficient pressure so that the drilling fluid can be sprayed downward along the flushing hole 211 on the flushing section 21. The flushing hole 211 also functions as a nozzle, spraying the drilling fluid towards the lower part of the fishing tool to flush the rock cuttings 5 ​​below the fish 4. However, the present invention is not limited to this. The range of the difference between the inner diameter of the flushing section 21 and the outer diameter of the fish 4 can also be arbitrarily selected according to actual operational needs, and is not limited to the range of 5 to 12 mm defined in this embodiment. The present invention does not make specific limitations in this regard.

[0052] Alternatively, a suitable axial distance must also be maintained between the flushing section 21 and the lower end of the retrieval tool. Specifically, the axial distance between the flushing section 21 and the lower end of the retrieval tool can be 3 to 8 cm. Within this distance range, the drilling fluid can maintain sufficient pressure in the annulus above the flushing section 21, and the drilling fluid sprayed downward from the flushing hole 211 can also maintain a vertically downward spray direction. In other words, within this distance range, while increasing the drilling fluid velocity, the drilling fluid can be prevented from being sprayed directly towards the well wall, causing well wall erosion. However, the present invention is not limited to this. The range of the axial distance between the flushing section 21 and the lower end of the retrieval tool can also be arbitrarily selected according to actual operational needs, and is not limited to the range of 3 to 8 cm defined in this embodiment. The present invention does not make specific limitations in this regard.

[0053] In this embodiment, the number of flushing holes 211 opened on the flushing section 21 can range from 6 to 12. Multiple flushing holes 211 can be distributed circumferentially in the flushing section 21. The arrangement of multiple flushing holes 211 distributed circumferentially ensures that there are flushing holes 211 at each circumferential position at the lower end of the annulus between the fish 4 and the flushing section 2, so that drilling fluid can be sprayed out. This can ensure that the axial pressure at each circumferential position in the annulus remains average, and the pressure of the drilling fluid sprayed towards the bottom of the fishing tool can also remain consistent in the circumferential direction, which can maximize the flushing effect on the rock cuttings 5 ​​around the fish 4. However, the present invention is not limited to this. The number of flushing holes 211 opened on the flushing section 21 can be arbitrarily selected according to the actual operation needs, and is not limited to the range of 6 to 12 limited in this embodiment. The present invention does not make a specific limitation in this regard.

[0054] In this embodiment, a female thread 12 may be provided at the upper end of the inner wall of the threading section 1. The female thread 12 can cooperate with the male thread at the lower end of the drill string installed on the upper part of the fishing tool. This can be used to fix the fishing tool to the upper drill string, thereby enabling the fishing tool and the upper drill string to form a complete fishing tool assembly. In the fishing operation, the fishing tool assembly can be lowered into the wellbore as a whole by the top drive of the drilling rig and reach the bottom of the well where the fish fell, so as to facilitate the fishing operation. However, the present invention is not limited to this. The connection structure between the upper end of the threading section 1 and the drill string can also be in other forms, not limited to the cooperation of the female thread and the male thread. The present invention does not make specific limitations on this.

[0055] Exemplary Example 2

[0056] This exemplary embodiment provides a method for retrieving fish that have fallen into a well.

[0057] The downhole fish retrieval method described in this exemplary embodiment can be performed using the integrated downhole flushing and hook-making retrieval tool as described in Exemplary Embodiment 1.

[0058] The salvage method may include:

[0059] Step 1: Based on the drilling operation conditions before the drill string broke, whether drilling fluid circulation could be established at that time, and whether there was any rock cuttings, estimate whether the fish was stuck in the cuttings and the severity of the rock cuttings.

[0060] Step 2: Determine the outer diameter of the fish based on the broken part of the drill bit. Determine if the external structure of the fish has a stabilizer or an increased outer diameter, and determine the distance L1 from the top of the fish to the stabilizer or the increased outer diameter.

[0061] Step 3: Determine the inner diameter of the hook-making part of the retrieval tool based on the size and structure of the fish. Inner diameter of the flushing section of the salvage tool Inner diameter of the flushing section of the salvage tool The distance from the lower end of the retrieval tool to the buckle is L2 = L1 - (7~10cm). The number of rinsing holes on the rinsing part of the retrieval tool is 6~12, the inner diameter of the rinsing hole is 5~10mm, and the depth of the rinsing hole is 4~7mm.

[0062] Step 4: Assemble the fishing tool with the upper drilling tool to form a fishing tool assembly, and then insert the fishing tool assembly into the well for drilling.

[0063] Step 5: When the distance between the retrieval tool and the top of the fish is the first distance (i.e., the length of a single bar, for example, the first distance is 7-10m), start the pump to circulate and flush the bottom of the well at 40%-60% of the normal drilling flow rate, and lower the retrieval tool to the second distance (for example, 2-3m) from the fish head at the first speed (for example, 7-12min / m).

[0064] Step 6: Start the top drive and rotate the retrieval tool at the first speed (e.g., 5-10 r / min). Continue the low displacement cycle and slow down the retrieval tool's lowering speed to the second speed (e.g., 15-20 min / m). Record parameters such as rotational torque T1, riser pressure P1, and weight HL1 of the index weight indicator.

[0065] Step 7: Continue to lower the retrieval tool assembly. When the riser pressure rises to the preset pressure difference range (e.g., 0.5-1 MPa), stop lowering the drill string and observe whether the weight indicator (i.e., the suspended weight of the retrieval tool) and rotation torque increase. If they do, it indicates that the inclined notch ring structure (guide part) at the bottom of the retrieval tool has begun to fit onto the top of the fallen fish.

[0066] Step 8: Slowly lower the retrieval tool assembly, keeping the suspended weight drop no more than 2T and the torque increase no more than 5000N·m. Adjust the drilling fluid discharge rate according to the increase in riser pressure to ensure that the riser pressure is within the range that the drilling equipment can withstand.

[0067] Step 9: Following the operation in step 8, the fish that fell into the well is gradually put into the inner tube of the retrieval tool. After 3 to 5 hours of continuous flushing, the rock debris between the fish and the well wall is gradually washed away and carried away by the drilling fluid.

[0068] (1) If the riser pressure suddenly drops by more than 2 MPa during the circulation flushing process, it indicates that the water hole inside the fish and the annulus at the bottom of the well have been cleared. At this time, the discharge rate can be increased to 70% to 85% of the drilling discharge rate and the circulation flushing can continue for 1 to 2 hours to fully remove the rock debris between the fish and the well wall, creating a good downhole environment for retrieval.

[0069] (2) If the pressure in the riser does not drop or drops by less than 2 MPa during the continuous flushing process after the fishing tool is put into the fish, it indicates that the water hole inside the fish and the annulus at the bottom of the well have not been cleared. When the top of the fish is 3 to 5 cm away from the hook-making part of the fishing tool, stop lowering the drill string and continue flushing for 2 to 3 hours.

[0070] Step 10: After the rock debris is cleared, stop the circulation and stop the top drive rotation (i.e. stop rotating the retrieval tool). Slowly lower the retrieval tool until the suspended weight drops by more than 25T. Turn on the top drive to rotate the retrieval tool at the second speed (e.g., 5r / min) to apply torque to the fallen fish to no more than 55000N·m. This completes the fastening part of the retrieval tool fastening the top material of the fallen fish.

[0071] Step 11: After the retrieval tool is combined with the fish, if the pump can be turned on, continue the circulation for 1 to 2 hours. If the pump cannot be turned on, perform pulling, pressing, and shocking operations to release the fish until it is released.

[0072] Step 12: Pull the drill string to the wellhead and complete the retrieval operation.

[0073] In summary, the inclined notch annular structure at the bottom of the retrieval tool of this invention can effectively scrape away rock debris between the fallen fish and the well wall when rotated clockwise, thus smoothly fitting the fallen fish into the retrieval tool. This effectively solves the technical problem of the fallen fish being difficult to enter the retrieval tool, and also effectively improves the quality of the hook-up at the top of the fallen fish, providing the retrieval tool with a pulling force of over 100 tons. The inner diameter of the annular protrusion structure of the retrieval tool is slightly larger than the outer diameter of the fallen fish. After being fitted with the fallen fish, drilling fluid circulation can be established through the perforated nozzle of the annular structure. At the same time, the perforated nozzle guides the drilling fluid jet towards the rock debris in the annulus between the fallen fish and the well wall. After circulating upwards through the annulus, the fallen fish is gradually fitted into the retrieval tool by rotating and pressing down. Simultaneously, due to the flow restriction effect of the retrieval tool, the drilling fluid jet... The erosive effect of the flow on the well wall is greatly reduced, avoiding the formation of a large "belly" that could lead to further collapse. The drilling fluid circulation between the retrieval tool and the wellbore through the annulus and flushing holes can be used to circulate and flush the bottom of the well, gradually clearing away rock debris from the wellbore and the fish. This significantly reduces the tensile force and rotational torque required to release the fish after the hook is created. Furthermore, there is a certain probability that after clearing the rock debris from the fish and the wellbore, the internal pressure difference of the fish can clear the blockage in the lower part of the water hole, thus establishing normal circulation from the water hole to the annulus. Before the application of the retrieval tool and method of this invention, conventional mother cones could not release the fish even with a pulling force of 190 tons. After thorough flushing with the retrieval tool of this invention, retrieval was successfully achieved with only 28 tons of pulling force, greatly reducing the pulling force required for retrieval.

[0074] Although the present invention has been described above in conjunction with exemplary embodiments and accompanying drawings, those skilled in the art should understand that various modifications can be made to the above embodiments without departing from the spirit and scope of the claims.

Claims

1. A downhole flushing and hook-making integrated retrieval tool, characterized in that, The salvage tool includes a buckling section and a rinsing section, wherein... The hook-making section is connected to the rinsing section. The inner wall of the hook-making section is provided with a hook-making part, which can hook the outer wall of the fish that has fallen into the hook-making section so as to tightly connect the fishing tool with the fish. The inner wall of the flushing section is provided with a flushing part, and the flushing part has several axially penetrating flushing holes. The falling fish in the flushing section can form an annulus with the inner wall of the flushing section. The drilling fluid can pass through the flushing holes along the annulus to flush the rock cuttings below the falling fish, so as to release the rock cuttings from the obstruction of the falling fish. The retrieval tool also includes a guide section, which is located at the lower end of the rinsing section. The guide section can scrape away rock debris around the fallen fish to guide the fish into the retrieval tool. The guide part is a ring structure with an inclined notch. The guide part can be rotated circumferentially to scrape rock debris and put the fallen fish into the retrieval tool. The inner diameter of the rinsing section is 5-12 mm larger than the outer diameter of the fish, so that the fish can pass through the rinsing section and enter the rinsing section and the buckling section. The distance between the flushing section and the lower end of the retrieval tool is 3-8 cm, which can increase the drilling fluid velocity and prevent the drilling fluid from eroding the well wall.

2. The integrated downhole flushing and hook-making retrieval tool according to claim 1, characterized in that, The snap-fitting part is a high-strength female cone retrieval thread. The high-strength female cone retrieval thread is used to snap the snap-fitting thread at the upper end of the fallen fish and provide sufficient pulling force to retrieve the fallen fish out of the well.

3. The integrated downhole flushing and hook-making retrieval tool according to claim 1, characterized in that, The rinsing part protrudes inward along the radial direction of the rinsing section, and the inner diameter of the rinsing section is larger than the inner diameter of the rinsing part. The difference between the inner diameter of the rinsing section and the inner diameter of the rinsing part is 2~5cm.

4. The integrated downhole flushing and hook-making retrieval tool according to claim 1, characterized in that, The number of flushing holes is 6 to 12, and the flushing holes are distributed circumferentially in the flushing section.

5. The integrated downhole flushing and hook-making retrieval tool according to claim 1, characterized in that, The upper end of the inner wall of the buckling section is provided with a female buckle, which can cooperate with the male buckle of the upper drill bit of the salvage tool to fix the salvage tool to the upper drill bit.

6. A method for retrieving fish that have fallen into a well, characterized in that, The retrieval method employs the integrated downhole flushing and hook-making retrieval tool as described in any one of claims 1 to 5. The retrieval method includes: assessing the degree to which the fish is stuck by downhole cuttings before retrieval; determining the structure and size of the fish, and determining the size of the retrieval tool based on the size of the fish; assembling the retrieval tool and drill string into the downhole; when the distance between the retrieval tool and the fish is a first distance, starting the pump to circulate and flush the bottom of the well, and then continuing to lower the retrieval tool to a second distance at a first speed; rotating the retrieval tool at a first rotational speed to reduce the circulation rate and slow down the lowering of the retrieval tool. The drill string is lowered to the second speed, and relevant parameters are recorded. When the riser pressure reaches the preset pressure difference range, the drill string is lowered to the second speed. The changes in parameters are used to determine whether the retrieval tool has caught the fish. After the retrieval tool catches the fish, circulation and flushing are maintained to flush the rock cuttings at the bottom of the well and bring them out of the wellhead by the drilling fluid. After the rock cuttings are cleaned up, circulation and rotation of the retrieval tool are stopped. The retrieval tool is lowered, and a preset torque is applied to the fish at the second speed to create a connection, thus connecting the retrieval tool with the fish. The retrieval tool and the fish are pulled up to the wellhead to complete the retrieval.

7. The method for retrieving fish from a well as described in claim 6, characterized in that, The dimensions of the fish being retrieved include the outer diameter φ1 of the fish, the distance L1 from the top of the fish to the stabilizer or the point where the outer diameter increases, and the dimensions of the retrieval tool include the inner diameter φ2 of the buckling part, the inner diameter φ3 of the rinsing section, the inner diameter φ4 of the rinsing part, and the length L2 from the lower end of the retrieval tool to the buckling part. in, φ2=φ1; φ3 = φ1 + (2~5cm); φ4 = φ1 + (5~12mm); L2 = L1 - (7~10cm).

8. The method for retrieving fish from a well as described in claim 6, characterized in that, The first distance is 7~10m, the first speed is 7~12min / m, the second distance is 2~3m, the first rotation speed is 5~10r / min, the second speed is 15-20min / m, the preset pressure difference range is 0.5~1MPa, the second rotation speed is 5r / min, and the preset torque is less than or equal to 55000N·m.

9. The method for retrieving fish from a well as described in claim 6, characterized in that, The recorded relevant parameters include one or more of the following: rotational torque T1, riser pressure P1, and weight of the index weight HL1.

10. The method for retrieving fish from a well as described in claim 6, characterized in that, The determination of whether the retrieval tool has been fitted onto the fallen fish includes determining whether the suspended weight and rotational torque of the retrieval tool have increased. If they have increased, it indicates that the lower end of the retrieval tool has begun to fit onto the top of the fallen fish.

11. The method for retrieving fish from a well as described in claim 6, characterized in that, The retrieval tool is kept in a continuous rinsing process for 3-5 hours after the fish has fallen into it. If the pressure in the riser suddenly drops by more than 2 MPa during the continuous rinsing process after the fishing tool is fitted onto the fish, the rinsing flow rate should be increased and the rinsing should continue for 1-2 hours. If the pressure in the riser does not drop or drops by less than 2 MPa during the continuous rinsing process after the fishing tool is inserted into the fish, then the lowering should be stopped when the top of the fish is 3-5 cm away from the hook-making part, and rinsing should continue for 2-3 hours.

12. The method for retrieving fish from a well as described in claim 6, characterized in that, The retrieval method also includes, after the retrieval tool is combined with the fallen fish, if the pump can be turned on, then continue to circulate for 1 to 2 hours; if the pump cannot be turned on, then perform the unblocking operation until the fallen fish is unblocked.

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