A double fluid unblocking operation method for composite card drill processing

Abstract

This invention provides a dual-liquid unsticking method for handling complex stuck drill bits. The method includes using a dual-liquid unsticking agent, comprising an oil-based unsticking agent and an acid-based unsticking agent used in combination. The method includes: calculating the dosage and additional amount of the dual-liquid unsticking agent for the soaking section, the soaking time and the reserved amount, and predicting the lost circulation zone; injecting the dual-liquid unsticking agent and sealing fluid into the drill string's waterholes, and then circulating them back to the annulus of the section to be soaked and unsticked; correcting the injection and displacement amounts of the dual-liquid unsticking agent, and using the cumulative pump stroke count to determine the well depth where the dual-liquid unsticking agent is located; ensuring the initial interface of the dual-liquid unsticking agent is below the predicted lost circulation zone; ensuring sufficient displacement amount of dual-liquid unsticking agent in the drill string during the soaking period; and performing soaking and unsticking during the process, including moving the unsticking drill string up and down and intermittently twisting the drill string until the stuck drill bit is freed. The advantage of this invention is that it can solve the problem of complex stuck drill bits.

Description

Technical Field

[0001] This invention relates to the field of drilling sticking and unsticking construction technology, specifically to a dual-liquid unsticking operation method for composite stuck drill bit treatment. Background Technology

[0002] In some carbonate formations in the Sichuan-Chongqing region, multiple pressure systems and the coexistence of high and low pressures create a complex formation pressure system, making differential pressure sticking a common occurrence. During drilling, rock fragments frequently fall, forming hard stuck sections. If these hard stuck sections are not addressed promptly, they can lead to adhesive sticking, resulting in a combined stuck pipe formation of rock fragments and differential pressure adhesion. Soaking with a release fluid can resolve differential pressure adhesion issues, but it is ineffective in removing hard stuck sections. Soaking with hydrochloric acid to remove hard stuck sections is highly susceptible to variations in acid concentration, volume, soaking time, and drilling pressure. Prolonged soaking and extended soaking times exacerbate well leakage, and soaking failures increase well control risks. The use of high-density drilling fluid in low-pressure formations creates high pressure differentials in the open hole, and the failure to promptly address downhole rock fragments and other hard stuck sections can lead to combined stuck pipe formations. Currently, in drilling operations, the treatment of combined stuck drill bits (hard stuck and differential pressure adhesion) relies solely on soaking with a single unsticking agent and acid. While soaking with the unsticking agent can resolve differential pressure adhesion, it is ineffective in removing hard stuck bits. Soaking with hydrochloric acid to remove hard stuck bits is highly susceptible to factors such as acid concentration, soaking volume, soaking time, and operating pressure. Prolonged soaking or prolonged soaking exacerbates well leakage, and soaking failure increases well control risks. Therefore, there is a lack of effective unsticking methods for dealing with combined stuck drill bits (hard stuck and differential pressure adhesion).

[0003] According to statistics, in a certain mining area A in the Sichuan-Chongqing region, there were 6 stuck wells and 9 stuck drill bit incidents. One attempt to free the wells involved moving the drill string and using shock; 8 attempts to use a release agent resulted in 5 successful attempts (62% success rate, average release time 16.8 hours); and 6 attempts to use hydrochloric acid resulted in 3 successful attempts (50% success rate, average release time 8.5 hours). The total lost time for handling the stuck drill bits in the 6 wells was 231.5 hours, with an average lost time of 25.72 hours per well.

[0004] In 2022, well X experienced a differential pressure collapse combined with stuck drill bit loss of 168 hours; in 2021, well Y experienced a differential pressure collapse combined with stuck drill bit loss of 240 hours; and in 2019, well Z experienced two differential pressure collapses combined with stuck drill bit loss, resulting in losses of 216 hours and 120 hours respectively. Therefore, it is necessary to design a dual-liquid unsticking method capable of quickly and efficiently unsticking drill bits that are both hard and adhered to the surface.

[0005] Chinese invention patent application CN113863883A, entitled "A Method for Unsticking Differential Pressure Drills and Its Application," provides a method for unsticking differential pressure drills. Chinese invention patent application CN116445147A, entitled "An Acid Solution and Acid Soaking Method for Unsticking Drills in Marine Formations," provides a method for unsticking hard-struck drills. However, neither provides an effective solution for unsticking drills with complex stuck conditions. Summary of the Invention

[0006] The purpose of this invention is to address at least one of the aforementioned shortcomings of the prior art. For example, one objective of this invention is to provide a dual-liquid unblocking method capable of solving the problem of combined stuck drill bits caused by hard clogging and adhesion.

[0007] To achieve the above objectives, the present invention provides a two-liquid unsticking method for handling composite stuck drill bits. The method includes using a two-liquid unsticking agent, which may include an oil-based unsticking agent and an acid-based unsticking agent used in combination. The acid-based unsticking agent may include HCl, a corrosion inhibitor, and an iron ion stabilizer. The concentration percentage of HCl in the acid-based unsticking agent is 10-30%, the corrosion inhibitor accounts for 1-9% of the volume of the acid-based unsticking agent, and the iron ion stabilizer accounts for 1-8% of the volume of the acid-based unsticking agent. The raw materials for the oil-based unsticking agent may include: 45-50 parts by volume of diesel oil, 1-8 parts by weight of organic clay, 1-7 parts by weight of emulsifier SP-80, 1-8 parts by volume of aluminum stearate, 1-8 parts by weight of CaO, 10-50 parts by weight of unsticking agent WNSST, and barite. The units for parts by volume and parts by weight correspond to cubic meters and tons, and the amount of barite used is determined according to the target density of the oil-based unsticking agent. The dosage can be determined based on the target density of the oil-based unsticking agent; and the method may include: adjusting drilling fluid properties to maintain pressure balance in the wellbore system; calculating the dosage and additional amount of the dual-liquid unsticking agent, soaking time and reserve amount for each soaking section, and predicting the lost circulation zone; organizing the construction operation to inject the dual-liquid unsticking agent and sealing fluid into the drill string waterhole, with the sealing fluid isolating the oil-based unsticking agent, acid unsticking agent and drilling fluid; and using a drilling pump to replace the drilling fluid volume, with the dual-liquid unsticking agent being replaced to the return drill fluid. The head is moved back to the annulus of the section to be soaked and unstuck; the injection and displacement amounts of the two-liquid unstuck agent are corrected, and the pump is reset to zero at the start of injection, using the cumulative pump count to determine the depth of the two-liquid unstuck agent; the acid unstuck agent soaks the lower formation, and the oil-based unstuck agent soaks the upper formation; during the soaking period, there is a sufficient amount of two-liquid unstuck agent in the drill string for displacement; after the two-liquid unstuck agent has been in place, the unstuck is unstuck according to the soaking time, during which the unstuck drill string is moved up and down and intermittently twisted until the unstuck is unstuck.

[0008] According to one or more exemplary embodiments of one aspect of the present invention, the correction of the injection and displacement amounts of the dual-liquid unsticking agent may include: determining the well depth of the oil-based unsticking agent and the acid unsticking agent based on the cumulative pump stroke count to determine whether the dual-liquid unsticking agent has been injected and displaced in place, wherein: the pump stroke count is reset to zero at the start of injection; when the oil-based unsticking agent exits the drill bit, the cumulative pump stroke count is m1 stroke; when the oil-based unsticking agent is located at the sticking point, the cumulative pump stroke count is m2 stroke; when the acid unsticking agent is located at the hard sticking point, the cumulative pump stroke count is m3 stroke; when the internal and external pressure difference is close to the equilibrium point, the cumulative pump stroke count is m4 stroke; when all the dual-liquid unsticking agent enters the casing shoe, the cumulative pump stroke count is m5 stroke, at which point the top depth of the oil-based unsticking agent is measured; when the top of the oil-based unsticking agent reaches the wellhead, the cumulative pump stroke count is m6 stroke; when all the dual-liquid unsticking agent is discharged, the cumulative pump stroke count is m7 stroke.

[0009] According to one or more exemplary embodiments of one aspect of the present invention, after the replacement is in place, the positive displacement can be increased by 0.5 to 1 m every 30 to 60 minutes. 3 .

[0010] According to an exemplary embodiment of one aspect of the present invention, the soaking and unblocking time can be 4 to 8 hours; during the soaking and unblocking period, the drill bit can be moved every 25 to 30 minutes.

[0011] According to an exemplary embodiment of one aspect of the present invention, when moving the drill bit, a variable tonnage moving method can be used to prevent stress concentration that could lead to drill bit fatigue.

[0012] According to an exemplary embodiment of one aspect of the present invention, the scope of the predicted leakage zone may include formation sections where well leakage has occurred during drilling, formation sections with low designed formation pressure coefficients, formation or key lithology interface sections, fractured formation sections with developed faults or fractures, and formation sections with good permeability.

[0013] According to an exemplary embodiment of one aspect of the present invention, the well section to be soaked and unstuck may include a drill collar, a drilling shock absorber in the middle of the weighted drill pipe, and the entire weighted drill pipe.

[0014] According to an exemplary embodiment of one aspect of the present invention, during the soaking process, the amount of oil-based unblocking agent and acid unblocking agent soaked in each well section can be no less than 3m, ensuring that there is still an effective amount of 1.3 to 1.7m after the contamination.

[0015] According to an exemplary embodiment of one aspect of the present invention, the acid-based unblocking agent may not soak the leak layer during the soaking period.

[0016] According to an exemplary embodiment of one aspect of the present invention, during the replacement process, if the acid unblocking agent must pass through the leakage layer, the flow rate can be increased by 0.2 to 0.5 m. 3 The single displacement allows the acid-dissolving agent to quickly pass through the leak layer.

[0017] Compared with the prior art, the beneficial effects of the present invention include at least one of the following:

[0018] (1) The method for unblocking the drilling fluid provided by the present invention is equipped with front and rear sealing and isolation fluids. Relying on the role of the front and rear sealing and isolation fluids, residual acid and drilling fluid can be effectively isolated.

[0019] (2) The method for unblocking the well after unblocking can replace the oil-based unblocking fluid with the stuck section of the well, pull the drill string to the interface between the oil-based unblocking fluid and the diesel isolation fluid, and then carry out residual fluid removal and drilling fluid treatment operations, which helps to avoid the well getting stuck again.

[0020] (3) The unblocking operation method provided by the present invention forms a gas block in the annulus by sealing the isolation fluid, which can further prevent the acid gas generated during acid soaking from rising and greatly reduce the pollution of secondary acid gas to drilling fluid. Attached Figure Description

[0021] 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:

[0022] Figure 1a A schematic diagram of the injection process for a first-stage replacement process according to an exemplary embodiment of the present invention is shown;

[0023] Figure 1b A schematic diagram of the displacement process in a first-stage injection process of an exemplary embodiment of the present invention is shown;

[0024] Figure 2 A schematic diagram of a two-stage injection process according to an exemplary embodiment of the present invention is shown.

[0025] Explanation of key figure labels:

[0026] 1-Sealing fluid, 2-Oil-based unblocking agent, 3-Acid unblocking agent, 4-Drilling fluid, 5-Falling block, 6-Adhesive. Detailed Implementation

[0027] In the following, a dual-liquid unsticking method for composite stuck drill bit processing according to the present invention will be described in detail with reference to exemplary embodiments.

[0028] The terms “S1”, “S2.1”, “S2.2”, “S2.3”, “S2.4”, “S2.5”, “S2.6”, “S2.7”, “S2.8”, “S2.9”, “S2.10”, “S2.11”, “S2.12”, “S2.13”, “S2.14”, “S2.15”, etc. used in this invention are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence.

[0029] Existing card unlocking methods may include the following steps:

[0030] S1: Inspect the circulation system, hoisting system, braking system, transmission system, wellhead tools, well control system, hydrogen sulfide protection equipment, and kill fluid storage equipment.

[0031] S2.1 Adjust the drilling fluid properties to maintain pressure balance in the wellbore system.

[0032] S2.2 Clean the wellbore with a large volume of circulating drilling fluid while ensuring downhole safety.

[0033] During S2.3 circulation, determine whether the drill string is short-circuited based on parameters such as displacement and pump pressure.

[0034] S2.4 During the operation of oil-based unblocking agents, for wells where leakage or well kick may occur, sufficient drilling fluid and plugging and well-killing materials should be reserved in accordance with well control regulations, and a safety construction plan should be prepared.

[0035] S2.5 Carefully inspect well control devices, fire-fighting facilities, and hydrogen sulfide protection equipment.

[0036] S2.6 Carefully inspect drilling pumps, high-pressure manifolds, and power equipment to ensure continuous operation of the injection carding process.

[0037] S2.7 On-site, an oil-based unblocking agent is prepared in the circulating tank according to downhole conditions. It typically consists of diesel fuel, oxidized asphalt, organic clay, surfactants, and weighting materials. Its density is slightly lower than the drilling fluid density in the well (0.05–0.2 g / cm³). 3 .

[0038] Before the S2.8 construction work begins, the on-site construction supervisor organizes and conducts technical briefings.

[0039] S2.9 Check that the ground gate switch is correct, and use the drilling pump to inject the prepared unblocking agent into the drill string water hole in one go.

[0040] S2.10 Use a drilling pump to replace the designed amount of drilling fluid, and return the unsticking agent from the drill bit. The amount returned to the annulus should be enough to soak the drill collar section.

[0041] S2.11 The annular fluid column pressure should be 4 MPa to 5 MPa greater than the fluid column pressure inside the drill string to ensure that there is a sufficient amount of displacing agent in the drill string within the designed soaking time.

[0042] During the S2.12 unblocking agent reaction, personnel must remain at their posts and assign dedicated personnel to guard the drilling fluid outlet to ensure well control safety (the soaking time will be determined based on the specific downhole conditions).

[0043] S2.13 Drilling tools that move up and down intermittently within the safe load range of the equipment and drilling tools.

[0044] S2.14 Inject the designed amount of drilling fluid every 30 minutes.

[0045] S2.15 After the stuck part is released, the moving drill string is used to recycle the unsticking agent.

[0046] Existing methods for unjamming drills can handle differential pressure jamming or hard jamming in a single operation, but they cannot effectively solve the combined problem of hard jamming and differential pressure jamming simultaneously. Therefore, this invention provides a dual-liquid unjamming method that can effectively solve the combined jamming problem. The following detailed description of a dual-liquid unjamming method for handling combined jamming drills is based on a first exemplary embodiment.

[0047] First exemplary embodiment

[0048] This exemplary embodiment provides a dual-liquid unsticking operation method for handling composite stuck drill bits.

[0049] Figure 1a A schematic diagram of the injection process for a first-stage replacement process according to an exemplary embodiment of the present invention is shown; Figure 1b A schematic diagram of the displacement process in a first-stage injection process of an exemplary embodiment of the present invention is shown; Figure 2 A schematic diagram of a two-stage injection process according to an exemplary embodiment of the present invention is shown below. Figures 1a-2 This exemplary embodiment describes a dual-liquid unsticking method for composite stuck drill handling.

[0050] In this exemplary embodiment, the two-liquid card removal method mainly involves using a two-liquid card removal agent, which mainly includes an acid-based card removal agent and an oil-based card removal agent. The acid-based card removal agent may include HCl, a corrosion inhibitor, and an iron ion stabilizer. The concentration percentage of HCl in the acid-based card removal agent is 10-30%, the corrosion inhibitor accounts for 1-9% of the volume of the acid-based card removal agent, and the iron ion stabilizer accounts for 1-8% of the volume of the acid-based card removal agent. The corrosion inhibitor may be a solid or liquid corrosion inhibitor; the iron ion stabilizer may be one or more of acetic acid, citric acid, or sulfurous acid. Preferably, the iron ion stabilizer may be acetic acid. The optimal formulation of the acid-based card removal agent may include 10-28% HCl, 2% corrosion inhibitor, and 1% iron ion stabilizer. Specifically, when preparing the acid-based card removal agent, HCl can be prepared first. If the concentration of the HCl to be prepared does not meet the requirements, the concentration of the HCl to be prepared can be adjusted, for example, by dilution, and then the corrosion inhibitor and iron ion stabilizer can be added according to the total volume of the prepared HCl. This optimal formula exhibits good compatibility and consistency, with no precipitation or flotation.

[0051] Oil-based unblocking agents may include diesel fuel, organoclay, SP-80, aluminum stearate, CaO, WNSST, and barite. The dosage relationship is as follows: 45-50 parts by volume of diesel fuel, 1-8 parts by weight of organoclay, 1-7 parts by weight of emulsifier SP-80, 1-8 parts by volume of aluminum stearate, 1-8 parts by weight of CaO, and 10-50 parts by weight of unblocking agent WNSST. The units for volume and weight are cubic meters and tons, respectively. The amount of barite is determined based on the target density of the oil-based unblocking agent. Specifically, when preparing the oil-based unblocking agent, diesel fuel can be added first, followed by organoclay, aluminum stearate, CaO, and WNSST according to the total volume of diesel fuel. Finally, barite is added to adjust the density of the oil-based unblocking agent to meet well control requirements. Through indoor comparative evaluation experiments, the oil-based unblocking agent prepared with high-temperature unblocking agent WNSST is preferred, with an adjustable density range of 0.90-1.85 g / cm³. 3 It has a temperature resistance of up to 150℃. This oil-based unsticking agent can not only remove stuck pipe caused by high pressure differential, but also remove stuck pipe caused by sedimentation beds. The success rate of unsticking in one attempt is over 85%. This formula has good compatibility with drilling fluids, and mixing it into the drilling fluid after unsticking can significantly improve its anti-sticking and lubrication capabilities. In particular, when the density of the oil-based unsticking agent is ≤1.60 g / cm³, it is effective. 3 The optimal formulation of the oil-based unblocking agent is as follows: 50 parts by volume of diesel oil, 2 parts by weight of organic clay, 2 parts by weight of emulsifier SP-80, 1.2 parts by volume of aluminum stearate, 3 parts by weight of CaO, and 35 parts by weight of unblocking agent WNSST. The amount of barite used is determined based on the target density of the oil-based unblocking agent. When the density of the oil-based unblocking agent is >1.60 g / cm³ 3 The optimal formulation for the oil-based unblocking agent is: 45 parts by volume of diesel oil, 3 parts by weight of organic clay, 3 parts by weight of emulsifier SP-80, 1.5 parts by volume of aluminum stearate, 3 parts by weight of CaO, and 40 parts by weight of unblocking agent WNSST. The amount of barite used is determined based on the target density of the oil-based unblocking agent. WNSST is a specific unblocking agent, a polyoxyethylene ether produced by Chongqing Weineng Drilling Additives Co., Ltd.

[0052] The dual-liquid card unlocking method of this exemplary embodiment mainly includes the following steps:

[0053] In accordance with the requirements for card release construction, all operating equipment for card release construction were inspected, and pre-construction treatments were carried out.

[0054] Adjust drilling fluid properties to maintain pressure balance in the wellbore system. Calculate the dosage and additional amount of the dual-liquid unsticking agent for each soaking section, the soaking time and reserve amount, and predict the lost circulation zone. Here, the segmented calculation of oil-based unsticking agent may include: calculating the dosage based on the mud cake location and well diameter, (drop location - mud cake location) × annular well diameter of that section = annular volume of that section; the segmented calculation of acid unsticking agent may include: calculating the dosage based on the drop location and well diameter, (drill bit location - drop location) × annular well diameter of that section = annular volume of that section. The additional amount may be the increased unsticking agent dosage considering a 10% annular wellbore enlargement rate. The reserve amount is the remaining portion of the unsticking agent or acid unsticking agent when the unsticking agent section reaches the predetermined position.

[0055] Organizing construction operations, such as Figure 2 As shown, the dual-liquid unsticking agent and sealing fluid 1 are injected downwards into the drill string's waterhole. The sealing fluid isolates the oil-based unsticking agent 2, the acid unsticking agent 3, and the drilling fluid 4. The sealing fluid 1 may include a pre-sealing fluid at the top layer of the dual-liquid unsticking agent, a post-sealing fluid at the bottom layer, and a middle sealing fluid between the two unsticking agents. The sealing fluid forms a gas trap in the annulus, further preventing the acidic gas generated during the acid unsticking agent's soaking process from rising, significantly reducing secondary acidic gas contamination of the drilling fluid. The sealing fluid may include diesel fuel or other liquids capable of isolating the unsticking agent during the unsticking process; the specific type can be selected according to the well site's operational needs.

[0056] The drilling fluid is replaced by a drilling pump, and the dual-liquid unsticking agent is pushed upwards to the drill bit and back into the annulus of the section to be unsticked. Figure 2 The piece 5, which caused the composite stuck drill problem in the annular space shown, was soaked with the adhering material 6.

[0057] Correct the injection and displacement amounts of the dual-liquid unblocking agent. Reset the pump to zero at the start of injection and use the cumulative pump count to determine the well depth where the dual-liquid unblocking agent is located.

[0058] Acid-based unblocking agent soaks the lower formation (the formation below the lost circulation zone), while oil-based unblocking agent soaks the upper formation (the formation above the lost circulation zone). To prevent prolonged soaking of the lost circulation zone with the acid-based unblocking agent and the associated risk of well leakage, the initial interface of the acid-based unblocking agent (i.e., the interface at the predetermined position where the liquid section of the acid-based unblocking agent reaches its peak) can be below the lost circulation zone during soaking. Furthermore, the acid-based unblocking agent is only permitted to pass rapidly through the lost circulation zone after unblocking or when discharging the two-liquid unblocking agent mixture. The initial interface of the oil-based unblocking agent can be either above or below the lost circulation zone.

[0059] During the soaking period, there is a sufficient amount of two-liquid unsticking agent in the drill string to replace it, meaning that there is a sufficient reserve in the drill string for replacement during the soaking period.

[0060] After the two-component unsticking agent has been in place, the drill bit is soaked and unsticked according to the soaking time. During this period, the drill bit is moved up and down and intermittently twisted until it is unsticked.

[0061] In this exemplary embodiment, due to the limited capacity of the circulation tank and the fact that drilling fluid inlet and outlet are both in the same tank, without cumulative pump flushing correction, it is impossible to know how much has been displaced or where the dual-liquid unsticking agent has been displaced. Therefore, metering correction is required. The correction of the injection and displacement amounts of the dual-liquid unsticking agent may include: determining the well depth of the oil-based and acid-based unsticking agents based on the cumulative pump flushing count to determine whether the dual-liquid unsticking agent has been injected and displaced in place, including:

[0062] The pump is zeroed when injection begins.

[0063] When the oil-based unblocking agent exits the drill bit, the cumulative pump stroke is m1 stroke.

[0064] When the oil-based unblocking agent is located at the sticking point, the cumulative pumping is m2 pumping.

[0065] When the acid-dissolving agent is located at the hard-blocking point, the cumulative pump stroke is m3 strokes.

[0066] When the internal and external pressure difference is close to the equilibrium point, the cumulative pump stroke is m4 strokes.

[0067] When both the oil-based unblocking agent and the acid unblocking agent have entered the upper casing, pump a total of m5 pumps. At this time, measure the top depth of the oil-based unblocking agent to determine whether the top of the oil-based unblocking agent has reached the wellhead.

[0068] When the top of the oil-based unblocking agent reaches the wellhead, the cumulative pumping volume is m6.

[0069] When all the two-liquid unblocking agent has been discharged, the cumulative pump flushing level is m7.

[0070] In this exemplary embodiment, the soaking and unblocking time can be 4 to 8 hours; for example, 4.6 hours, 5.1 hours, or 5.8 hours. During the soaking and unblocking period, the top can be 0.5 to 1 meter every 30 to 60 minutes. 3 For example, 0.6m of positive peak every 32 minutes, 47 minutes, or 56 minutes. 3 0.8m 3 or 0.9m 3 Move the drill string every 25-35 minutes, for example, every 26, 27, or 32 minutes, to perform a release operation. While waiting for the release agent to react, observe and record changes in stand pressure each time the drilling fluid is applied to the surface, and maintain unobstructed circulation. In particular, if mud cake peels off the wellbore or sand settles during the soaking process, to prevent annular blockage, immediately stop soaking if there is an abnormal increase in stand pressure, promptly drain the release agent, and ensure unobstructed flow inside and outside the drill string.

[0071] Furthermore, during the soaking process, soaking combined with vibration yields better results in releasing stuck drill bits. When moving the drill string, the number of movements should be strictly limited, and a variable tonnage method should be adopted to prevent stress concentration that could lead to fatigue fracture of the drill string. If vibration is applied during the lifting process, care should be taken to ensure that the drill string reaches its tensile strength before applying vibration, to avoid exceeding the tensile strength of the drill string and causing it to break.

[0072] In this exemplary embodiment, intermittent torsion is performed within the torsional strength range of the drill string, based on the original suspended weight; the drill string is moved up and down during torsion. Typically, the drill string operates at 20-50% of its minimum torsional yield strength. Preferably, the torsional value is controlled at 50% (within the clamping torque range), and the tensile value is controlled at 30-50%. After every 3-5 movements, the original suspended weight is returned, and the torque is released. For example, a weak point in a drill string is a first-grade 139.7mm double-step threaded drill string, with steel grade S135, wall thickness 9.17mm, tensile strength 2760KN, torsional strength 94050N.m, and clamping torque 55728N.m; while controlling the torsional value at 50% (within the clamping torque range) and torsion of the drill string (torque 0-45KN·m), the tensile value is controlled at 50% of the movement range (suspended weight 300-1600KN). After every 3-5 movements, for example, 4 times, the original suspended weight is returned, and the torque is released. Here, weak points in the drill string can be determined based on the drill string's tool structure, dimensions, tool grade, and usage time. For example, weak points may be found at variable thread joints in drill string assemblies of the same size, at dimensional changes in assemblies of different sizes, or at the top drive or rotary table where the maximum tensile and torsional loads are applied. Problems are prone to occur at weak points during torque stress and require close monitoring.

[0073] Additionally, when the torque is increased, the tensile and torsional strength of the drill string will decrease. At this point, it's crucial to control the lifting tonnage carefully. If either the tensile ultimate strength or the torsional yield strength of the drill string approaches or reaches its limit, the other parameter must not approach or reach its limit strength. When applying torque, avoid overtightening the threads, leaving room for explosive loosening.

[0074] In this exemplary embodiment, the well section to be soaked and unstuck may include the drill collar, the drilling shock absorber in the middle of the weighted drill pipe, and the entire weighted drill pipe.

[0075] In this exemplary embodiment, during soaking, the liquid height of both the oil-based unblocking agent and the acid unblocking agent in each well section should not be less than 3m, ensuring that an effective quantity of 1.3 to 1.7m remains after contamination, for example, 1.4m, 1.5m, or 1.7m. Here, contamination before and after means that the oil-based unblocking agent column and the acid unblocking agent column each have four contact interfaces, and that an effective quantity of 1.3 to 1.7m remains after contamination of the four contact interfaces. During injection and displacement operations, the displacement volume each time should not be less than 0.5m. 3 To ensure the substitution is effective.

[0076] In this exemplary embodiment, the placement of the oil-based unsticking agent and the acid-based unsticking agent is adjusted according to the stuck drill situation. For example, different replacement processes can be implemented depending on the stuck drill situation, and the replacement process may include a primary replacement process, a secondary replacement process, or a tertiary replacement process. For example, Figure 1a As shown, during the first-stage injection and replacement process, the pre-sealing and isolation fluid, acid-based unblocking agent 3, intermediate isolation fluid, oil-based unblocking agent 2, and post-sealing and isolation fluid can be injected into the wellbore in the following order from top to bottom, so that the wellbore contains, from top to bottom, post-sealing and isolation fluid, oil-based unblocking agent 2, intermediate isolation fluid, acid-based unblocking agent 3, and pre-sealing and isolation fluid; Figure 2 As shown, during a two-stage injection-displacement process, the pre-sealing and isolating fluid, oil-based unblocking agent 2, intermediate isolating fluid, acid unblocking agent 3, and post-sealing and isolating fluid are injected into the wellbore in the following order from top to bottom: post-sealing and isolating fluid, acid unblocking agent 2, intermediate isolating fluid, oil-based unblocking agent 2, and pre-sealing and isolating fluid. During a three-stage injection-displacement process, the pre-sealing and isolating fluid, oil-based unblocking agent, intermediate isolating fluid, acid unblocking agent, intermediate isolating fluid, oil-based unblocking agent, and post-sealing and isolating fluid are injected into the wellbore in the following order from top to bottom: post-sealing and isolating fluid, oil-based unblocking agent intermediate isolating fluid, acid unblocking agent intermediate isolating fluid, oil-based unblocking agent, and pre-sealing and isolating fluid. During displacement, the layer distribution order of the two-liquid unblocking agent and isolating fluid is reversed compared to the injection order. For example, as shown... Figure 1b As shown, in the first-stage displacement process, the reagents displaced into the annulus are positioned from top to bottom as follows: pre-sealing and isolating fluid, acid-based unblocking agent 3, intermediate isolating fluid, oil-based unblocking agent 2, and post-sealing and isolating fluid. Specifically, before injecting the dual-liquid unblocking agent, it is possible to check for accidental leaks in ground pipelines and drill bits.

[0077] In this exemplary embodiment, the dual-liquid unsticking operation method may further include: replacing the stuck section with a subsequent oil-based unsticking agent or a post-sealing fluid. For example, if a single-stage or three-stage injection process is used, after unsticking, the subsequent oil-based unsticking agent is replaced with the stuck section; if a two-stage injection process is used, after unsticking, the subsequent post-sealing fluid is replaced with the stuck section. The drill string is pulled up to the interface between the oil-based unsticking agent and the last layer of oil-based unsticking fluid before the unsticking, and then residual fluid removal and drilling fluid treatment are performed; the top drive is rotated, the pump is slowly started, and residual acid (here, residual acid refers to the product of the chemical reaction between hydrochloric acid and formation cuttings or wellbore in the open hole, including unused acid unsticking agent or contaminants formed by mixing with drilling fluid and other media) is discharged directly to the emergency pool; after draining the residual fluid, the drill string is moved up and down, the drilling fluid density is circulated and adjusted, the mud performance is treated, and a short trip-out operation is performed for verification.

[0078] In this exemplary embodiment, during the soaking period, the acid-based unblocking agent may not soak the drain layer; that is, soaking begins from the time the unblocking agent is in place until the end of soaking, and the top layer of the acid-based unblocking agent is kept as low as possible below the drain layer. If the acid-based unblocking agent must pass through the drain layer during the replacement process, for example, after unblocking or when discharging the two-component unblocking agent, the distance can be increased by 0.2 to 0.5 m. 3 The single displacement amount allows the acid unblocking agent to quickly pass through the lost circulation zone, shortening the residence time of the acid unblocking agent in the lost circulation zone and reducing the risk of hydrochloric acid corroding the mud cake in the lost circulation zone, leading to well leakage.

[0079] In summary, the advantages of the present invention may include at least one of the following:

[0080] (1) The unblocking agent operation method provided by the present invention can effectively solve the composite stuck drill problem of hard stuck + pressure differential adhesion, and improve construction efficiency;

[0081] (2) The method for unblocking operations provided by the present invention improves safety and environmental protection measures on the basis of solving the problem of stuck drill in the well site, better meets the needs of leakage prevention and unblocking, improves the timeliness of fault handling, and minimizes the economic losses and negative impacts caused by compound stuck drill.

[0082] (3) The method for unblocking operations provided by the present invention further enhances the degree of risk control and avoids situations such as safety risks and increased drilling costs.

[0083] Although the present invention, a dual-liquid unsticking method for handling composite stuck drills, has been described above in conjunction with exemplary embodiments, those skilled in the art should understand that various modifications and changes can be made to the exemplary embodiments of the present invention without departing from the spirit and scope defined by the claims.

Claims

1. A dual-liquid unblocking method for handling composite stuck drill bits, characterized in that, The method includes using a two-component unblocking agent, which comprises an oil-based unblocking agent and an acid-based unblocking agent used in combination; wherein the acid-based unblocking agent comprises HCl, a corrosion inhibitor, and an iron ion stabilizer, wherein the concentration percentage of HCl in the acid-based unblocking agent is 10-30%, the corrosion inhibitor accounts for 1-9% of the volume of the acid-based unblocking agent, and the iron ion stabilizer accounts for 1-8% of the volume of the acid-based unblocking agent; The raw materials for the oil-based unblocking agent include: 45-50 parts by volume of diesel oil, 1-8 parts by weight of organic clay, 1-7 parts by weight of emulsifier SP-80, 1-8 parts by volume of aluminum stearate, 1-8 parts by weight of CaO, 10-50 parts by weight of unblocking agent WNSST, and barite. The units for volume and weight are cubic meters and tons, respectively. The amount of barite used is determined based on the target density of the oil-based unblocking agent. The method includes: Adjust the drilling fluid properties to maintain pressure balance in the wellbore system; Calculate the dosage and additional amount of dual-liquid unblocking agent for each soaking section, the soaking time and the reserved amount, and predict the leakage layer. Organize the construction operation and inject the dual-liquid unsticking agent and sealing and isolating fluid into the water hole of the drill string. The sealing and isolating fluid isolates the oil-based unsticking agent, acid unsticking agent and drilling fluid. The drilling fluid volume is replaced by a drilling pump, and the dual-liquid unsticking agent is displaced to the return drill bit and returned to the annulus of the section of the well to be soaked and unsticked; Correct the injection and displacement amounts of the dual-liquid unblocking agent. Reset the pump to zero at the start of injection and use the cumulative pump count to determine the well depth where the dual-liquid unblocking agent is located. Acid-based unblocking agent was used to soak the lower formation, while oil-based unblocking agent was used to soak the upper formation. During the soaking period, there is a sufficient amount of two-liquid unsticking agent in the drill string to replace the stuck material. After the two-component unsticking agent has been in place, the drill bit is soaked and unsticked according to the soaking time. During this period, the drill bit is moved up and down and intermittently twisted until it is unsticked.

2. The dual-liquid unblocking method for handling composite stuck drill bits according to claim 1, characterized in that, The correction of the injection and displacement amounts of the dual-liquid unblocking agent includes: The depth of the well where the oil-based unsticking agent and the acid unsticking agent are located is determined based on the cumulative number of pump strokes to determine whether the dual-liquid unsticking agent has been injected and replaced in place. The pump is zeroed at the start of injection; When the oil-based unblocking agent exits the drill bit, the cumulative pump stroke is m1 stroke; When the oil-based unblocking agent is located at the sticking point, the cumulative pumping is m2 pumping. When the acid-dissolving agent is located at the hard-blocking point, the cumulative pump stroke is m3 strokes. When the internal and external pressure difference is close to the equilibrium point, the cumulative pump stroke is m4 strokes; When all the dual-liquid unblocking agent has entered the casing shoe, pump a total of m5 times, and at this time measure the top depth of the oil-based unblocking agent. When the top of the oil-based unblocking agent reaches the wellhead, the cumulative pumping volume is m6. When all the two-liquid unblocking agent has been discharged, the cumulative pump flushing level is m7.

3. The dual-liquid unblocking method for composite stuck drill bit processing according to claim 1, characterized in that, After the replacement is in place, the top is 0.5-1m every 30-60 minutes. 3 .

4. The dual-liquid unblocking method for composite stuck drill bit processing according to claim 1, characterized in that, The soaking and unblocking time is 4 to 8 hours; during the soaking and unblocking period, the drill string is moved every 25 to 30 minutes.

5. The dual-liquid unblocking method for composite stuck drill bit processing according to claim 4, characterized in that, When operating the drilling tool, the variable tonnage method is used, which can lead to stress concentration and drill tool fatigue.

6. The dual-liquid unblocking method for composite stuck drill bit processing according to claim 1, characterized in that, The scope of the predicted leakage zones includes well sections in formations where well leakage has occurred during drilling, well sections in formations with low designed formation pressure coefficients, well sections at the junction of formations or key lithologies, well sections in fractured formations with developed faults or fractures, and well sections in formations with good permeability.

7. The dual-liquid unblocking method for composite stuck drill bit processing according to claim 1, characterized in that, The section of well to be soaked and unstuck includes the drill collar, the drilling shock absorber in the middle of the weighted drill pipe, and the entire weighted drill pipe.

8. The dual-liquid unblocking method for composite stuck drill bit processing according to claim 1, characterized in that, During the soaking process, the amount of oil-based unblocking agent and acid unblocking agent soaked in each well section shall not be less than 3m, ensuring that there is still an effective amount of 1.3 to 1.7m after the contamination.

9. The dual-liquid unblocking method for composite stuck drill bit processing according to claim 1, characterized in that, During the soaking period, the acid-based unblocking agent does not soak the leak layer.

10. The dual-liquid unblocking method for composite stuck drill bit processing according to claim 9, characterized in that, During the replacement process, if the acid unblocking agent must pass through the leakage layer, increase the concentration by 0.2–0.5 m. 3 The single displacement allows the acid-dissolving agent to quickly pass through the leak layer.

Images