A solvent lift soakback method for high-wax wells

Abstract

The application discloses a kind of high-wax well solvent lifting soaking well testing methods, when well-through wireline tool string is placed into tubing, well-through wireline tool string is placed into resistance after, along the inner wall between well-through wireline tool string and tubing, pump into wax dissolving agent, utilize wax dissolving agent to soak and dissolve the wax ring between the inner wall between well-through wireline tool string and tubing, then, after well-through, the test tool string is placed into resistance along tubing, along the inner wall between test tool string and tubing, pump into wax dissolving agent, utilize wax dissolving agent to soak and dissolve the wax ring between the inner wall between test tool string and tubing, utilize the solution cavity structure formed between well-through wireline tool string or test tool string and the inner wall of tubing, place into wax dissolving agent to dissolve wax, can reduce the consumption of wax dissolving agent, and also greatly improve the use rate of wax dissolving agent, effectively solve the problem that tool string meets resistance, meets card, test tool drops, effectively reduce operation risk and cost, improve data acquisition success rate.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas reservoir construction technology, specifically relating to a method for solvent-lifting immersion well testing in high wax content wells. Background Technology

[0002] During the development and production of oil and gas reservoirs, dynamic monitoring and data acquisition are necessary to deepen geological understanding, facilitate efficient block development, support reserve declarations and scheme preparation, including but not limited to formation pressure and temperature monitoring, and production-injection profile monitoring. In some areas, gas reservoirs are deeply buried (8271m), have high pressure (144MPa), high wax content (18.83%), and complex fluid phases. The wax content in the wellbore makes dynamic monitoring data acquisition difficult and challenging. In the past three years, dynamic monitoring was conducted on 63 wells, with 37 encountering obstacles and 38 achieving success, a success rate of 60%. There have also been instances where, during well testing, the wireline tool string encountered obstruction, and during the handling process, the tool string twisted and fell into the well, complicating downhole operations and even affecting oil and gas production.

[0003] For wells with high wax content, in order to improve the success rate of data acquisition, the method of coiled tubing dredging + wireline well testing or coiled tubing dredging + coiled tubing well testing is usually adopted. However, the above technical methods have problems such as long cycle, high cost and slow team organization.

[0004] Currently, to save production costs, when using the wireline well-dredging + wireline well-testing method, if the tool string encounters obstruction, it is usually pulled up to the wellhead, and a wax solvent is pumped into the wellbore. Figure 4 As shown, after dissolving the blockage in the wellbore, a wireline tool string is then lowered. This method has the problems of high consumption of wax solvent and high cost, as well as low dissolution efficiency, which leads to the problem of encountering obstruction and jamming again in the second well test. Therefore, it is necessary to optimize the wireline dropping and retrieval well test process in a targeted manner to improve the success rate of well test operations and meet the needs of geological data acquisition. Summary of the Invention

[0005] The purpose of this invention is to provide a method for solvent-assisted immersion well testing in high wax content wells, in order to overcome the problems of existing tool strings encountering obstruction, jamming, and test tools falling off, effectively reducing operational risks and costs, and improving the data acquisition success rate.

[0006] A method for well testing using solvent-lifting immersion in high-wax-content wells includes the following steps:

[0007] Insert the well-clearing wireline into the tubing. When the wireline encounters resistance, pump a wax solvent between the wireline and the inner wall of the tubing. The wax solvent will soak and dissolve the wax ring between the wireline and the inner wall of the tubing, thus completing the well-clearing operation. Then, remove the wireline.

[0008] Then, the test tool string is inserted along the tubing. When the test tool string encounters resistance, a wax solvent is pumped in between the test tool string and the inner wall of the tubing. The wax solvent is used to soak and dissolve the wax ring between the test tool string and the inner wall of the tubing. After the test tool string reaches the set position for testing, the test tool string is retrieved, and the well test is completed.

[0009] Preferably, the maximum diameter of the wellbore wireline tool or test tool string is smaller than the inner diameter of the tubing.

[0010] Preferably, a tensile test is used during the lowering of the test tool string or well-drilling wire tool string to determine whether the test tool string or well-drilling wire tool string encounters any obstruction.

[0011] Preferably, after reaching the set position, the tension value of the test tool string or well-drilling wire tool string at the current position is obtained. If the tension value of the test tool string or well-drilling wire tool string at the current position is less than the set threshold, it indicates whether the test tool string or well-drilling wire tool string has encountered obstruction; otherwise, no obstruction has been encountered.

[0012] Preferably, the blowout preventer installed at the wellhead is pressure tested before well testing.

[0013] Preferably, after the pressure test is passed, the pressure is released to the equilibrium pressure. After the pressure inside the blowout preventer pipe is balanced with the pressure inside the well, the system is fully opened only after ensuring that the blowout preventer system is sealed and leak-free.

[0014] Preferably, when inserting the wireline tool string into the tubing for well cleaning, the speed should not exceed 10 m / min within 50 m of the wellhead and 15 m / min within 100 m of the diameter change position or target position.

[0015] Preferably, the speed of lifting the well wire guide string from the tubing should not exceed 70 m / min.

[0016] Preferably, when the test tool string is placed into the tubing for well cleaning, the speed should not exceed 10 m / min within 50 m of the wellhead and 15 m / min within 100 m of the diameter change position or target position.

[0017] Preferably, the speed at which the test tool string is lifted from the tubing does not exceed 70 m / min.

[0018] Compared with the prior art, the present invention has the following beneficial technical effects:

[0019] This invention provides a method for solvent-assisted well testing in high-wax-content wells. The method involves inserting a wireline tool into the tubing. When the wireline encounters resistance, a wax dissolving agent is pumped between the wireline tool and the inner wall of the tubing. The wax dissolving agent dissolves the wax ring between the wireline tool and the tubing, completing the well cleaning process. The wireline tool is then removed. Next, a test tool is inserted into the tubing. When resistance is encountered, a wax dissolving agent is pumped between the test tool and the inner wall of the tubing. This process further dissolves the wax ring between the test tool and the tubing. After soaking and dissolving, the test tool string is retrieved once it reaches the set position for testing, thus completing the well test. A cavity structure is formed between the wellbore wireline tool string or test tool string and the inner wall of the tubing, allowing for the placement of a wax solvent to dissolve the wax. This reduces the amount of wax solvent consumed and, because dissolution occurs from the top of the wax ring, significantly improves the utilization rate of the wax solvent. The wellbore wireline tool string or test tool string can be lowered or raised immediately after wax dissolution, effectively solving problems such as tool string obstruction, jamming, and test tool drop. This effectively reduces operational risks and costs, and improves the success rate of data acquisition.

[0020] Preferably, the maximum diameter of the wellbore wire guide or test tool string used is smaller than the inner diameter of the tubing; this avoids the problem of jamming due to the tubing's inner diameter being too small during the lowering process.

[0021] Preferably, when the well-clearing wireline tool or test tool string is inserted into the tubing for well-clearing, it is lowered and raised at a set speed to accurately obtain the tension data of the well-clearing wireline tool or test tool string, so as to perform the wax melting operation in a timely manner and improve work efficiency. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the well testing method for solvent-lifted immersion in high wax content wells, as described in an embodiment of the present invention.

[0023] Figure 2 This is a schematic diagram of wax plugging in a high-wax-content wellbore, as shown in an embodiment of the present invention.

[0024] Figure 3 This is a schematic diagram of wellbore blockage after the high wax content well tool string encounters obstruction during operation, as described in an embodiment of the present invention.

[0025] Figure 4 This is a schematic diagram of a wellbore for pumping wax solvent using existing methods.

[0026] Figure 5 This is a schematic diagram of solvent-supported immersion in a high-wax-content well, as shown in an embodiment of the present invention.

[0027] In the diagram, 1. casing, 2. tubing, 3. wax ring, 4. packer, 5. perforation section, 6. casing shoe, 7. oil and gas reservoir, 8. wax solvent, and 9. tool string. Detailed Implementation

[0028] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0029] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0030] like Figure 1 As shown, this invention provides a method for high-wax-content well solvent lifting and immersion during well testing, which solves the problems of tool string obstruction, jamming, and test tool drop during wireline well testing operations, effectively reducing operational risks and costs, and improving data acquisition success rate; specifically including the following steps:

[0031] Insert the well-clearing wire tool string into tubing 2. When the well-clearing wire tool string encounters resistance, pump wax solvent along the inner wall between the well-clearing wire tool string and tubing 2. Use the wax solvent to soak and dissolve the wax ring 3 between the well-clearing wire tool string and the inner wall of tubing 2, thus completing the well-clearing work. Then remove the well-clearing wire tool string.

[0032] Then, the test tool string is inserted along tubing 2. When the test tool string encounters resistance, a wax solvent is pumped in between the test tool string and the inner wall of tubing 2. The wax solvent is used to soak and dissolve the wax ring 3 between the test tool string and the inner wall of tubing 2. After the test tool string reaches the set position for testing, the test tool string is retrieved, and the well test is completed.

[0033] like Figure 2As shown, in the oil and gas reservoir well targeted by this application, the casing 1 is installed in the area of ​​the oil and gas reservoir 7. The casing 1 is equipped with a tubing 2 and a casing shoe 6 is installed on the outside of the bottom of the casing 1 to increase the stability of the casing 1 installation. The lower end of the casing 1 is located in the perforation section 5 in the oil and gas reservoir 7 area, with multiple perforations. A packer 4 is installed on the upper end of the casing 1 in the oil and gas reservoir 7 area.

[0034] The maximum diameter of the wellbore wire guide or test tool string used should be smaller than the inner diameter of tubing 2; during the lowering process, avoid the problem of the tubing 2 getting stuck due to its small inner diameter.

[0035] Based on the reservoir department's dynamic monitoring plan and data acquisition plan, this application targets gas wells with high wax content in the block's condensate oil, complex well fluid properties, and a tendency for wax blockage, aromatic hydrocarbon blockage, and mixed blockage to be encountered in the wellbore, and conducts wireline well testing operations.

[0036] During the lowering of the test tool string or well-drilling wireline, the wax on the inner wall of the tubing will accumulate at the end of the test tool string or well-drilling wireline, as shown in Figure 3, forming a wax ring accumulation structure. If the lowering of the test tool string or well-drilling wireline encounters excessive resistance, wax dissolution treatment is required. Specifically, as shown in Figure 3... Figure 5 As shown, a wax solvent is pumped between the tool string and the inner wall of the tubing. The wax solvent is used to soak and dissolve the wax ring between the tool string and the inner wall of the tubing, thus completing the well cleaning operation. After the wax dissolution treatment is completed, when the test tool string or well cleaning wire tool string successfully reaches the set position, the test tool string or well cleaning wire tool string is then lifted to check the tool's passage through the diameter change.

[0037] During the lowering of the test tool string or well-drilling wireline, a tensile test is conducted to determine whether the test tool string or well-drilling wireline encounters resistance. The specific steps are as follows:

[0038] After reaching the set position, obtain the tension value of the test tool string or well-drilling wire tool string at the current position. If the tension value of the test tool string or well-drilling wire tool string at the current position is less than the set threshold, it indicates whether the test tool string or well-drilling wire tool string has encountered any obstruction; otherwise, no obstruction has been encountered.

[0039] In one embodiment of this application, the test tension is increased every 100m from a set depth position (180-220m), and the tension change is calculated to ensure that the tool can be safely pulled out within the limit tension range.

[0040] Before well testing, the following preparations are required: preparation of the well testing winch, preparation of the blowout preventer, preparation of the downhole tool string, and installation and pressure testing of the equipment.

[0041] Preparation of well testing winch: The winch drum is made of φ3.8mm sulfur-resistant steel wire with tensile strength that meets the requirements of this construction project. It is used to hoist the well cleaning wire tool string and the testing tool string.

[0042] The well testing winch is driven by a hydraulic drive device. It is necessary to check that the hydraulic oil is at the standard position: above 2 / 3 of the scale.

[0043] All connecting pipelines of the well testing winch drive device are firm and without leakage. All power supply lines are connected reliably, without short circuit or open circuit.

[0044] Check that the metering device of the well testing winch is in good condition, the tension is accurate, and all control valves are flexible and easy to use.

[0045] Check that the winch meets the operation requirements.

[0046] Blowout preventer equipment preparation:

[0047] Select a wellhead blowout preventer equipment with a pressure resistance level of 105 MPa or above.

[0048] Conduct a base pressure test on the blowout preventer equipment to ensure that the blowout preventer equipment is qualified.

[0049] Ensure that the wire blowout preventer of the blowout preventer equipment has flexible opening and closing.

[0050] Install and connect the flange connection head connecting the blowout preventer equipment to the wellhead to ensure the sealing of the connection.

[0051] All kinds of control pipelines and hand-operated pumps supporting the blowout preventer equipment are prepared and in place.

[0052] Downhole tool string preparation: including a test tool string and a hole cleaning wire tool string.

[0053] The hole cleaning wire tool string includes a wire rope cap, a universal joint, a weight rod, a shock absorber and a hole cleaning gauge, and is hoisted by a well testing winch to form a hole cleaning wire tool string.

[0054] The test tool string includes a wire rope cap, a weight rod, a pressure gauge carrier tube and a setting joint.

[0055] Prepare a wire rope cap matching the wire, and fix the wire screw cap at the front end of the hole cleaning wire tool string.

[0056] Prepare enough weight of weight rods according to the construction requirements, and check that the connection of the weight rods is firm.

[0057] Confirm that the pressure gauge is within the calibration validity period, in good condition without damage, and program it according to the test requirements.

[0058] Before the hole cleaning wire tool string or test tool string is lowered into the well, the test engineer takes pictures and archives them, and records clearly the instrument number, size, and thread type. It can only be lowered into the well after being confirmed on-site by the test monitoring technicians in the operation area.

[0059] Installation and pressure test of equipment:

[0060] a. Place the well test winch at a position set at a distance from the wellhead. In this application, the distance from the wellhead is set to 15m-25m, with the center of the well test winch drum facing the wellhead.

[0061] b. Inspect the connection of the blowout preventer and the test tool string or well cleaning wire tool string as required;

[0062] c. Connect the blowout preventer to the choke string (the blowout preventer with a vent valve should be connected to the lower end of the blowout preventer string);

[0063] d. Install a connecting flange and a wire blowout preventer above the wax removal gate;

[0064] e. Pressure test on the ground to 1.2 times the wellhead pressure, and stabilize the pressure for 30 minutes;

[0065] f. After the blowout preventer is connected to the wellhead, fix the ground anchor and tension rope, and connect the test pressure pipeline;

[0066] g. Use a grease pump to inject sealing grease into the wellhead to 1.2 times the wellhead pressure to seal the blowout preventer;

[0067] h. Use a pressure testing pump to test the blowout preventer at the wellhead. Pressurize slowly in stages, stabilizing the pressure for 5 minutes at each stage and stabilizing the pressure for 15 minutes at the last stage. If there is no leakage, it is considered qualified.

[0068] i. After the pressure test is passed, slowly open the pressure relief valve to release the pressure until it is the same as the wellhead pressure, then close the inlet needle valve and release the pressure of the test pump to zero.

[0069] After the pressure test is passed, the well is purged first, followed by testing.

[0070] After the pressure test is passed, the pressure is released to the equilibrium pressure, and the test gate is slowly opened. After the pressure inside the blowout preventer pipe is balanced with the pressure inside the well, the gate is fully opened only after ensuring that the blowout preventer system is sealed and leak-free. During this process, the number of turns of the valve is accurately recorded as the baseline number for normal valve operation.

[0071] When inserting the well-clearing wireline into tubing 2 for well-clearing, the following requirements apply to the tripping speed of the well-clearing wireline: During the tripping process: the speed should not exceed 10 m / min within 50 m of the wellhead, and the speed should not exceed 15 m / min at 100 m from the diameter change position or the target position; during the tripping process, the speed should not exceed 70 m / min.

[0072] During the lowering of the well-drilling wireline tool string, wax melting is required to prevent obstruction or jamming. After wax melting, once the well-drilling wireline tool string successfully reaches the set position, it is then raised to check the tool's diameter change. At the set depth position (180-220m), the tension is tested every 100m, and the tension change is calculated to ensure that the tool can be safely retrieved within the limit tension range.

[0073] Specifically: When the wireline tool string encounters obstruction during its lowering process, place the wireline tool string at the obstruction point and pump in a wax solvent along the gap between the wireline tool string and the inner wall of the tubing. This allows the wax solvent to slide down along the gap between the outer wall of the wireline tool string and the inner wall of the tubing, dissolving the wax ring through lifting and soaking, thereby resolving the wellbore blockage and ensuring that the wireline tool string can be lowered normally.

[0074] Deploying the test tool string: After successful solvent lifting and immersion, the well cleaning process is completed. The well cleaning wire tool string is then removed, and the test tool string is deployed again.

[0075] Connecting the test tool string: After connecting and fixing the wire rope cap (φ38mm), weight rod (φ50mm), pressure gauge support (φ45mm) and landing connector (φ52mm) in sequence, pull or lift the test tool string into the blowout preventer, connect the blowout preventer string to the wire rope blowout preventer, and perform a pressure test;

[0076] After the pressure test is passed, fully open the wax removal gate, lower the test tool string and measure the gradient, with a speed not exceeding 50m / min;

[0077] During the lowering of the test tool string, if it is necessary to prevent obstruction or jamming, wax melting is required. After the wax melting is completed, when the test tool string successfully reaches the set position, the test tool string is then raised to check the tool's diameter change. At the set lower depth position (180-220m), the test tension is increased every 100m, and the tension change is calculated to ensure that the test tool string can be safely lifted out within the limit tension range.

[0078] Specifically: When the test tool string encounters obstruction during its lowering process, the test tool string is placed at the obstruction point, and a wax solvent is pumped in between the test tool string and the inner wall of the tubing. The wax solvent then slides down the gap between the outer wall of the test tool string and the inner wall of the tubing. Through lifting and soaking, the wax ring is dissolved, thereby solving the wellbore blockage problem and ensuring that the test tool string can be lowered normally.

[0079] Retrieve test tool string:

[0080] Connect the pressure gauge retrieval tool string: wire rope cap (φ38mm) + tungsten carbide weight bar (φ50mm) + shock absorber (φ45mm) + JDC (φ46mm); pull or raise the test tool string into the blowout preventer (BOP), connect the BOP string to the wireline BOP, and then perform a pressure test. After the pressure test is passed, fully open the dewaxing gate, lower the pressure gauge retrieval tool to retrieve the pressure gauge. After successful retrieval of the pressure gauge, raise the wellhead to measure the gradient. After the test is completed, restore the wellhead, and the test is finished. If the pressure gauge retrieval test tool string encounters obstruction during lowering, pump a wax dissolving agent along the inner wall between the tool string and the tubing to dissolve the wax ring between the tool string and the inner wall of the tubing until the test tool is successfully retrieved, and the operation is completed.

[0081] The present invention discloses a method for solvent-assisted well testing in high-wax-content wells. The method involves inserting a wireline tool into the tubing. When the wireline encounters resistance, a wax dissolving agent is pumped between the wireline tool and the inner wall of the tubing. The wax dissolving agent dissolves the wax ring between the wireline tool and the tubing, completing the well cleaning process. The wireline tool is then removed. Next, a test tool is inserted into the tubing. When resistance is encountered, a wax dissolving agent is pumped between the test tool and the inner wall of the tubing. This process dissolves the wax ring between the test tool and the tubing. After soaking and dissolving, the test tool string is retrieved once it reaches the set position for testing, thus completing the well test. A cavity structure is formed between the wellbore wireline tool string or test tool string and the inner wall of the tubing. Wax dissolving agent is then placed inside to dissolve the wax, reducing the amount of wax dissolving agent consumed. Dissolving from the top of the wax ring also significantly improves the utilization rate of the wax dissolving agent. The wellbore wireline tool string or test tool string can be lowered or raised immediately after wax dissolution, effectively solving problems such as tool string obstruction, jamming, and test tool drop. This effectively reduces operational risks and costs, and improves the success rate of data acquisition.

Claims

1. A method for well testing using solvent-lifting immersion in high-wax-content wells, characterized in that, Includes the following steps: Insert the well-clearing wireline into the tubing. When the wireline encounters resistance, pump a wax solvent between the wireline and the inner wall of the tubing. The wax solvent will soak and dissolve the wax ring between the wireline and the inner wall of the tubing, thus completing the well-clearing operation. Then, remove the wireline. Then, the test tool string is inserted along the tubing. When the test tool string encounters resistance, a wax solvent is pumped in between the test tool string and the inner wall of the tubing. The wax solvent is used to soak and dissolve the wax ring between the test tool string and the inner wall of the tubing. After the test tool string reaches the set position for testing, the test tool string is retrieved, and the well test is completed.

2. The well testing method for solvent-lifted immersion in high-wax-content wells according to claim 1, characterized in that, The maximum diameter of the wellbore wireline tool or test tool string is smaller than the inner diameter of the tubing.

3. The well testing method for solvent-lifted immersion in high-wax-content wells according to claim 1, characterized in that, During the lowering of the test tool string or well-drilling wire tool string, a tensile test is conducted to determine whether the test tool string or well-drilling wire tool string encounters any obstruction.

4. The well testing method for solvent-lifted immersion in high-wax-content wells according to claim 1, characterized in that, Before well testing, the blowout preventer installed at the wellhead is pressure tested.

5. The well testing method for solvent-lifted immersion in high-wax-content wells according to claim 1, characterized in that, After the pressure test is passed, the pressure is released to the equilibrium pressure. Once the pressure inside the blowout preventer is balanced with the pressure inside the well, the system can be fully opened only after ensuring that the blowout preventer is sealed and leak-free.

6. The well testing method for solvent-lifted immersion in high-wax-content wells according to claim 1, characterized in that, When inserting the wireline tool string into the tubing for well cleaning, the speed should not exceed 10 m / min within 50 m of the wellhead, and should not exceed 15 m / min within 100 m of the diameter change position or target position.

7. The well testing method for solvent-lifted immersion in high-wax-content wells according to claim 1, characterized in that, The speed during the lifting of the wellbore wire rope from the tubing should not exceed 70 m / min.

8. The well testing method for solvent-lifting and soaking high-wax-content wells according to claim 1, characterized in that, When lowering the test tool string into the tubing for well cleaning, the speed should not exceed 10 m / min within 50 m of the wellhead, and should not exceed 15 m / min within 100 m of the diameter change position or target position.

9. The well testing method for solvent-lifting and soaking high-wax-content wells according to claim 1, characterized in that, The speed at which the test tool string is lifted from the tubing shall not exceed 70 m / min.

Images