Wellhead injection device and method for solid asphalt inhibitor

Abstract

The invention discloses a solid asphalt inhibitor wellhead injection device and method, and belongs to the technical field of oil and gas production engineering, the solid asphalt inhibitor wellhead injection device comprises an injection pipe column, the upper end of the injection pipe column is provided with a blind plug, the lower end is fixedly connected with a flat valve, and the lower end of the flat valve is connected with a paraffin removal valve on a Christmas tree. The blind plug and the flat valve are arranged at the upper end and the lower end of the injection pipe column correspondingly, the feeding and feeding amount of the solid asphalt inhibitor can be controlled, and whether asphaltene blockage occurs in an oil and gas well or not is determined according to the field production condition; the solid asphalt inhibitor is periodically put, operation is convenient, the solid asphalt inhibitor injection step can be repeated till the injection amount meets the design requirement, and the injection period can be adjusted on site according to production data and experimental test results. Long-term stable production of a shaft of an asphaltene blocked well and effective prevention of asphalt blockage of a high-pressure oil-gas well are realized through a process of regularly injecting a solid asphalt inhibitor into a well mouth.

Description

Technical Field

[0001] The present invention belongs to the technical field of oil and gas production engineering, and particularly relates to a wellhead injection device and method for solid asphalt inhibitors. Background Art

[0002] Ultra-deep oil resources buried more than 6,000 meters deep are an important replacement area for increasing crude oil reserves and production. However, during the production process of oil wells, heavy components in the crude oil separate and accumulate to form "thrombus", blocking the tubing or surface pipelines. Especially for ultra-deep oil wells, the impact on production and safety is very serious. The problem of oilfield asphalt blockage affects the long-term prevention and control of asphaltene in oil wells.

[0003] Currently, the research on solid asphaltene inhibitors still remains at the stage of formula development and preparation methods, lacking research on implementation processes in high-pressure oil and gas wells such as deep / ultra-deep wells. For example, the invention patent "A Solid Asphaltene Inhibitor and Its Preparation Method" with the application number CN202110746319.9, the invention patent "A Preparation Method and Use of a Solid Asphaltene Inhibitor" with the application number CN202110003905.4, and the invention patent "A Solid Asphaltene Inhibitor and Its Preparation Method and Application" with the application number CN202011332452.1. Due to the lack of suitable processes for high-pressure oil and gas wells in existing solid asphalt inhibitors, there is no effective preventive technology for asphalt blockage in high-pressure oil and gas wells. Once blocked, it relies on passive treatments such as chemical deplugging with liquid asphalt dispersants and paraffin removers or coiled tubing dredging. Even if the blockage problem is solved in the wellbore, it will still appear on the ground, greatly affecting production. Currently, there is no mature and available technology for preventing and controlling asphalt blockage in high-pressure oil and gas wells, and it is urgent to study the technology for preventing and controlling asphalt blockage in ultra-deep oil wells to ensure their continuous production. Summary of the Invention

[0004] In order to overcome the above-mentioned drawbacks of the prior art, the purpose of the present invention is to provide a wellhead injection device and method for solid asphalt inhibitors to solve the problems that existing solid asphalt inhibitors lack suitable processes for high-pressure oil and gas wells and there is no effective preventive technology for asphalt blockage in high-pressure oil and gas wells.

[0005] To achieve the above purpose, the present invention adopts the following technical solutions:

[0006] A wellhead injection device for solid asphalt inhibitors includes an injection string. A blind plug is provided at the upper end of the injection string, and a flat valve is fixedly connected to the lower end. The lower end of the flat valve is connected to the paraffin removal valve on the Christmas tree.

[0007] Preferably, a pressure gauge for safety pressure testing is also provided on the injection string.

[0008] Preferably, the upper end of the injection string is connected to the blind plug by threads.

[0009] Preferably, the lower end of the injection string is fixedly connected to the flat valve through the cooperation of a flange and a flange plate.

[0010] Preferably, the flat valve is connected to the paraffin removal valve on the production tree through a screw thread or a reducing flange.

[0011] Preferably, its length does not exceed 20 m.

[0012] The present invention also discloses a method for injecting a solid asphalt inhibitor into a wellhead using the wellhead injection device for a solid asphalt inhibitor according to any one of the above, including the following steps:

[0013] Judge the blockage condition of the high-pressure oil and gas wellbore and the precipitation depth of asphaltene to determine the injection depth of the solid asphalt inhibitor in the wellbore;

[0014] Determine the parameters of the solid asphalt inhibitor according to the injection depth of the solid asphalt inhibitor in the wellbore;

[0015] Fill the solid asphalt inhibitor into the injection device according to the determined parameters of the solid asphalt inhibitor;

[0016] Inject the solid asphalt inhibitor and track the production data of the oil well in real time to judge whether asphaltene blockage occurs in the oil and gas well.

[0017] Preferably, after determining the injection depth of the solid asphalt inhibitor in the wellbore, it is also necessary to ensure that the position above the asphaltene precipitation in the wellbore is unobstructed.

[0018] Preferably, the step of determining the parameters of the solid asphalt inhibitor according to the injection depth of the solid asphalt inhibitor in the wellbore specifically includes the following steps:

[0019] S201: Determine the density of the solid asphalt inhibitor according to the density of the crude oil, and the density difference between the solid asphalt inhibitor and the crude oil is not less than 0.1 g / cm3;

[0020] S202: Determine the maximum outer diameter of the solid asphalt inhibitor according to the inner diameter of the wellbore tubing string corresponding to the injection depth of the solid asphalt inhibitor in the wellbore, and the difference between its outer diameter and the inner diameter of the tubing above the asphaltene precipitation depth in the wellbore is not less than 5 mm;

[0021] S203: Determine the minimum length of the solid asphalt inhibitor according to the inner diameter of the wellbore tubing string corresponding to the injection depth of the solid asphalt inhibitor in the wellbore, and its length is not less than 3 times the inner diameter of the tubing above the asphaltene precipitation depth in the wellbore.

[0022] Preferably, filling the solid asphalt inhibitor into the injection device specifically includes the following steps:

[0023] S301: Install and connect the wellhead injection device on the upper part of the wellhead production tree and pass the pressure test;

[0024] S302: Close both the blind plug and the flat valve of the wellhead injection device.

[0025] S303: Slowly open the flat valve at the bottom of the wellhead injection device to relieve the pressure of the wellhead injection device.

[0026] S304: Fill the solid asphalt inhibitor into the wellhead injection device through the bottom, and close the flat valve at the bottom; connect the paraffin removal valve on the Christmas tree.

[0027] When injecting the solid asphalt inhibitor, open the flat valve and the paraffin removal valve, and the solid asphalt inhibitor falls into the wellbore under the action of gravity.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] A solid asphalt inhibitor wellhead injection device disclosed in the present application is provided with a blind plug and a flat valve at the upper and lower ends of the injection string respectively, which is beneficial to controlling the delivery and delivery volume of the solid asphalt inhibitor, and determining whether asphaltene plugging occurs in the oil and gas well in combination with the on-site production situation; the solid asphalt inhibitor is periodically delivered, with convenient operation, and the steps of delivering the solid asphalt inhibitor can be repeated until the delivery volume meets the design requirements. The on-site injection cycle can be adjusted according to the production data and experimental test results. The long-term stable production of the wellbore of the asphaltene plugging well and the effective prevention of asphalt plugging in high-pressure oil and gas wells are realized through the process of regularly injecting the solid asphalt inhibitor at the wellhead.

[0030] A method for injecting a solid asphalt inhibitor at the wellhead disclosed in the present application first determines whether there is asphalt plugging in the wellbore according to the actual production situation of the high-pressure oil and gas well on site, judges the plugging situation of the wellbore of the high-pressure oil and gas well and the precipitation depth of asphalt, determines the parameters of the solid asphalt inhibitor, ensures the smoothness of the wellbore above the asphalt precipitation position through measures, places the wellhead injection device at the upper end of the paraffin removal valve of the Christmas tree through a crane, fills the solid asphalt inhibitor into it through the bottom of the wellhead injection device, and closes the bottom flat valve. Connect the wellhead injection device, close both its blind plug and flat valve, open the lower flat valve of the wellhead injection device and the paraffin removal valve of the Christmas tree, and the solid asphalt inhibitor falls into the wellbore under the action of gravity. Close the paraffin removal valve of the Christmas tree, separate the wellhead injection device from the Christmas tree with the assistance of a crane, open the bottom flat valve, fill the solid asphalt inhibitor into it through the bottom of the wellhead injection device, and repeat the steps of injecting the solid asphalt inhibitor until the injection volume meets the design requirements. Real-time track production data such as oil well production, oil pressure, and casing pressure, and at the same time observe whether there is leakage at the wellhead, and determine whether there is asphalt plugging in the oil and gas well according to the on-site production situation; take an oil sample at regular intervals, conduct a determination of the asphalt content in the crude oil, and evaluate the prevention and control effect and the effective period of asphalt plugging in the oil and gas well. On site, the injection cycle can be adjusted according to the production data and experimental test results, and the long-term stable production of the wellbore of the asphalt plugging well can be realized through the process of regularly injecting the solid asphalt inhibitor at the wellhead. Description of the Drawings

[0031] Figure 1 It is a schematic structural diagram of a wellhead injection device for a solid asphalt inhibitor.

[0032] Figure 2 It is a schematic flow diagram of a method for injecting a solid asphalt inhibitor at the wellhead.

[0033] Wherein: 1 - blind plug; 2 - injection string; 3 - flange; 4 - steel ring; 5 - flange plate; 6 - flat valve; 7 - pressure gauge; 8 - Christmas tree; 9 - paraffin removal valve. Detailed Embodiments

[0034] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

[0035] It should be noted that the terms "first", "second", etc. in the description, claims and the above-mentioned drawings of the present invention are used to distinguish similar objects, and do not necessarily have to be used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the present invention described here can be implemented in an order other than those illustrated or described here. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0036] The present invention will be further described in detail below with reference to the drawings:

[0037] See Figure 1 , this application discloses a wellhead injection device for solid asphalt inhibitor, which includes an injection string 2. A blind plug 1 is arranged at the upper end of the injection string 2, and a flat valve 6 is fixedly connected to the lower end. The lower end of the flat valve 6 is connected to the paraffin removal valve 9 on the Christmas tree 8. The wellhead injection device is lifted to the upper end of the Christmas tree 8 at the wellhead by a crane, and 4-6 technicians cooperate to place it above the paraffin removal valve 9 of the Christmas tree 8. The solid asphalt inhibitor is filled into it through the bottom of the wellhead injection device, and the bottom flat valve is closed. Connect the wellhead injection device, close its blind plug and flat valve 6, open the lower flat valve 6 of the wellhead injection device and the paraffin removal valve 9 of the Christmas tree 8, and the solid asphalt inhibitor falls into the wellbore under the action of gravity. Close the paraffin removal valve 9 on the Christmas tree 8, separate the wellhead injection device from the Christmas tree 8 with the assistance of the crane, open the bottom flat valve 6, fill the solid asphalt inhibitor into it through the bottom of the wellhead injection device, and repeat the steps of injecting the solid asphalt inhibitor until the injection volume meets the design requirements. The solid asphalt inhibitor is periodically injected, which is convenient to operate. The steps of injecting the solid asphalt inhibitor can be repeated, and the injection cycle can be adjusted on site according to production data and experimental test results. The long-term stable production of the wellbore blocked by asphaltene and the effective prevention of asphalt blockage in high-pressure oil and gas wells are realized through the process of regularly injecting solid asphalt inhibitor at the wellhead.

[0038] In some embodiments, a wellhead injection device for a solid asphalt inhibitor includes an injection string 2. A blind plug 1 is provided at the upper end of the injection string 2, and a flat valve 6 is fixedly connected to the lower end. The lower end of the flat valve 6 is connected to a paraffin removal valve 9 on the Christmas tree 8. A pressure gauge 7 for safety pressure testing is also provided on the injection string 2. The upper end of the injection string 2 is connected to the blind plug 1 by threads, and the lower end is fixedly connected to the flat valve 6 by mating a flange 3 with a flange plate 5. The flat valve 6 is connected to the paraffin removal valve 9 on the Christmas tree 8 by threads or a reducing flange. The wellhead injection device is lifted to the upper end of the wellhead Christmas tree 8 by a crane, and 4 to 6 technicians cooperate to place it above the paraffin removal valve 9 of the Christmas tree 8. The solid asphalt inhibitor is filled into it through the bottom of the wellhead injection device, and the bottom flat valve is closed. The wellhead injection device is connected, and its blind plug and flat valve 6 are both closed. The lower flat valve 6 of the wellhead injection device and the paraffin removal valve 9 of the Christmas tree 8 are opened, and the solid asphalt inhibitor falls into the wellbore under the action of gravity. The paraffin removal valve 9 on the Christmas tree 8 is closed, and with the assistance of the crane, the wellhead injection device is separated from the Christmas tree 8. The bottom flat valve 6 is opened, and the solid asphalt inhibitor is filled into it through the bottom of the wellhead injection device. The steps of injecting the solid asphalt inhibitor are repeated until the injection volume meets the design requirements.

[0039] Real-time track production data such as oil well production, oil pressure, and casing pressure, and at the same time observe whether there is any leakage at the wellhead, and determine whether there is asphalt plugging in the oil and gas well according to the on-site production situation; take an oil sample at regular intervals to carry out the determination of the crude oil asphaltene content, and evaluate the prevention and control effect and the validity period of asphalt plugging in the oil and gas well. The injection cycle can be adjusted on-site according to the production data and experimental test results, and the long-term stable production of the wellbore of the asphalt plugging well can be realized through the process of regularly injecting the solid asphalt inhibitor at the wellhead.

[0040] In some embodiments, a solid asphalt inhibitor wellhead injection device includes an injection string 2, the upper end of the injection string 2 is provided with a blind plug 1, the lower end is fixedly connected with a flat valve 6, and the lower end of the flat valve 6 is connected to the wax removal valve 9 on the Christmas tree 8. The injection string 2 is also provided with a pressure gauge 7 for safety pressure testing, the upper end of the injection string 2 is connected to the blind plug 1 through a thread, and the lower end is fixedly connected to the flat valve 6 through a flange 3 and a flange plate 5, and the flat valve 6 is connected to the wax removal valve 9 on the Christmas tree 8 through a thread or a reducer flange. Combined with different dosages of reagents, the length of the wellhead injection device is determined, the longest is generally not more than 20m, and there are 2-4 sections connected and sealed by thread. Because the wellhead injection device is heavy, generally more than 500kg, the wellhead injection device is hoisted to the upper end of the wellhead Christmas tree by a crane, and 4-6 technicians cooperate to place it at the upper end of the Christmas tree wax removal valve, fill the solid asphalt inhibitor into it through the bottom of the wellhead injection device, and close the bottom flat valve. Connect the wellhead injection device, close its blind plug and flat valve 6, open the flat valve 6 at the bottom of the wellhead injection device and the wax cleaning valve of the Christmas tree, and the solid asphalt inhibitor falls into the wellbore under the action of gravity. Close the wax cleaning valve of the Christmas tree, separate the wellhead injection device from the Christmas tree with the help of a crane, open the bottom flat valve, fill the solid asphalt inhibitor into it through the bottom of the wellhead injection device, and repeat the solid asphalt inhibitor injection steps until the injection amount meets the design requirements.

[0041] Real-time tracking of production data such as oil well production, oil pressure, casing pressure, etc., while observing whether there is leakage at the wellhead, and determining whether asphaltene blockage has occurred in the oil and gas well based on the on-site production situation; taking oil samples at regular intervals, conducting crude oil asphaltene content determination, and evaluating the prevention and control effect and validity period of asphaltene blockage in oil and gas wells. The on-site filling cycle can be adjusted according to production data and experimental test results, and the long-term stable production of the wellbore of the asphaltene-blocked well can be achieved through the process of regularly injecting solid asphalt inhibitors at the wellhead.

[0042] See also Figure 2 , the present invention also proposes a wellhead injection method of solid asphalt inhibitor suitable for high-pressure oil and gas wells, the specific steps are as follows:

[0043] S1: Determine the blockage of the wellbore of high-pressure oil and gas wells and the depth of asphaltene precipitation to determine the depth of the solid asphalt inhibitor in the wellbore;

[0044] S2: Determine the parameters of the solid asphalt inhibitor according to the depth of the solid asphalt inhibitor in the wellbore;

[0045] S3: Filling the solid asphalt inhibitor in the injection device according to the determined solid asphalt inhibitor parameters;

[0046] S4: inject solid asphalt inhibitor and track oil well production data in real time to determine whether asphaltene blockage occurs in the oil and gas well.

[0047] The present application discloses a method for injecting solid asphalt inhibitor into a wellhead. First, according to the actual production situation of the high-pressure oil and gas well, determine whether the wellbore is blocked by asphalt, judge the blockage of the wellbore and the depth of asphalt precipitation, determine the parameters of the solid asphalt inhibitor, take measures to ensure that the asphalt precipitation position in the wellbore is shallow and unobstructed, place the wellhead injection device at the upper end of the wax cleaning valve of the oil tree by a crane, fill the solid asphalt inhibitor into it through the bottom of the wellhead injection device, and close the bottom flat valve. Connect the wellhead injection device, close its blind plug and flat valve, open the lower flat valve of the wellhead injection device and the wax cleaning valve of the oil tree, and the solid asphalt inhibitor falls into the wellbore under the action of gravity. Close the wax cleaning valve of the oil tree, separate the wellhead injection device from the oil tree with the help of the crane, open the bottom flat valve, fill the solid asphalt inhibitor into it through the bottom of the wellhead injection device, and repeat the solid asphalt inhibitor injection steps until the injection amount meets the design requirements. Real-time tracking of production data such as oil well production, oil pressure, casing pressure, etc., while observing whether there is leakage at the wellhead, and determining whether asphaltene blockage has occurred in the oil and gas well based on the on-site production situation; taking oil samples at regular intervals, conducting crude oil asphaltene content determination, and evaluating the prevention and control effect and validity period of asphaltene blockage in oil and gas wells. The on-site filling cycle can be adjusted according to production data and experimental test results, and the long-term stable production of asphaltene-blocked wells can be achieved through the process of regularly injecting solid asphalt inhibitors at the wellhead.

[0048] In some embodiments, a method for injecting solid asphalt inhibitor into a wellhead suitable for high-pressure oil and gas wells comprises the following specific steps:

[0049] S1: Determine the blockage of the wellbore of high-pressure oil and gas wells and the depth of asphaltene precipitation to determine the depth of the solid asphalt inhibitor in the wellbore;

[0050] Determine the blockage of high-pressure oil and gas wells and the depth of asphaltene precipitation

[0051] 1) First, determine whether the wellbore is blocked by asphalt based on the actual production conditions of the high-pressure oil and gas well. You can also analyze the components of the blockages brought out by mechanical wax removal and continuous tubing dredging operations to determine whether it is asphalt blockage;

[0052] 2) Determine the wellbore blockage and asphaltene precipitation depth of high-pressure oil and gas wells. Determine the wellbore blockage depth based on the previous well cleaning operation or continuous tubing dredging operation. Determine the depth of solid asphalt inhibitor in the wellbore based on the asphaltene precipitation depth of the wellbore. The depth of the solid asphalt inhibitor should not be less than the asphaltene precipitation depth of the wellbore. The depth of wax precipitation in the wellbore should preferably be more than 50m;

[0053] S2: Determine the parameters of the solid asphalt inhibitor according to the depth of the solid asphalt inhibitor in the wellbore;

[0054] 1) Determine the density of the solid asphalt inhibitor based on the density of the crude oil, with the density difference between the solid asphalt inhibitor and the crude oil being no less than 0.1 g / cm3;

[0055] 2) Determine the maximum outer diameter of the solid asphalt inhibitor according to the inner diameter of the wellbore tubing string corresponding to the depth where the solid asphalt inhibitor is to be lowered into the wellbore. The difference between its outer diameter and the inner diameter of the tubing above the asphaltene precipitation depth in the wellbore is no less than 5 mm, facilitating the fall of the solid asphalt inhibitor in the tubing;

[0056] 3) Determine the minimum length of the solid asphalt inhibitor according to the inner diameter of the wellbore tubing string corresponding to the depth where the solid asphalt inhibitor is to be lowered into the wellbore. Its length is no less than 3 times the inner diameter of the tubing above the asphaltene precipitation depth in the wellbore, avoiding sticking caused by the accumulation of the agent during the lowering process;

[0057] Ensure unobstructed flow above the asphaltene precipitation position in the wellbore

[0058] 1) Install a wireline operation blowout preventer and pressure test it to be qualified according to requirements; if a reduced-diameter and reduced-pressure flange is required, it shall be prepared by the construction organization unit;

[0059] 2) It is acceptable to use wireline operation to ream the well or coiled tubing operation to dredge to a depth deeper than the depth where the solid asphalt inhibitor is to be lowered into the wellbore, ensuring unobstructed flow in the tubing, which is beneficial for the subsequent lowering of the solid asphalt inhibitor, and pressure test it to be qualified according to requirements;

[0060] 3) If the wireline operation to ream the well cannot reach the specified depth, then adopt coiled tubing operation to dredge to a depth deeper than the asphaltene precipitation depth in the wellbore;

[0061] S3: Fill the solid asphalt inhibitor in the injection device according to the determined parameters of the solid asphalt inhibitor;

[0062] 1) Install and connect the wellhead injection device above the wellhead Christmas tree and pressure test it to be qualified;

[0063] 2) Close both the blind plug and the flat valve 6 of the wellhead injection device;

[0064] 3) Slowly open the flat valve at the bottom of the wellhead injection device to relieve the pressure of the wellhead injection device;

[0065] 4) Fill the solid asphalt inhibitor into it through the bottom of the wellhead injection device and close the bottom flat valve.

[0066] S4: Inject the solid asphalt inhibitor and continuously track the production data of the oil well to judge whether asphaltene blockage occurs in the oil and gas well.

[0067] 1) Connect the wellhead injection device, open the lower flat valve 6 of the wellhead injection device and the paraffin removal valve of the Christmas tree, and the solid asphalt inhibitor falls into the wellbore under the action of gravity;

[0068] 2) Close the paraffin removal valve of the Christmas tree. With the assistance of a crane, separate the wellhead injection device from the Christmas tree, open the bottom flat valve, and fill the solid asphalt inhibitor into it through the bottom of the wellhead injection device.

[0069] 3) Repeat the steps of injecting the solid asphalt inhibitor until the injection volume meets the design requirements.

[0070] 4) Close the blind plug and flat valve 6 of the wellhead injection device.

[0071] On-site test effect tracking and evaluation

[0072] Track production data such as oil well production, oil pressure, and casing pressure in real time. At the same time, observe whether there is any leakage at the wellhead, and determine whether there is asphalt plugging in the oil and gas well according to the on-site production situation.

[0073] Take an oil sample at regular intervals, conduct the determination of the crude oil asphalt content, and evaluate the prevention and control effect and the effective period of asphalt plugging in the oil and gas well.

[0074] Subsequent injection of solid asphalt inhibitor

[0075] 1) On-site, the injection cycle can be adjusted according to production data and experimental test results. Through the process of regularly injecting the solid asphalt inhibitor at the wellhead, long-term stable production of the wellbore of the asphalt-plugged well can be achieved.

[0076] 2) The solid asphalt inhibitor has adaptability and an effective period. It needs to be regularly put in combination with the actual situation of a single well. Before the next delivery, it is necessary to clean the well first to ensure the wellbore is unobstructed before putting it in, so as to avoid ineffective delivery caused by the solid asphalt inhibitor being unable to reach the designated depth of the wellbore.

[0077] In some embodiments, to ensure the safety and controllability of the process of injecting the solid asphalt inhibitor into high-pressure oil and gas wells, the wellhead injection device needs to be pressure-tested according to requirements, and the device should be regularly observed for any leakage and damage.

[0078] In some embodiments, the wellhead injection device for the solid asphalt inhibitor can be disassembled after the injection volume in one time meets the production requirements. Before disassembly, it is necessary to first close the paraffin removal valve on the upper part of the Christmas tree to isolate its energy, and then disassemble the wellhead injection device for the solid asphalt inhibitor for subsequent injection use.

[0079]

Embodiment

[0080] Well M-1 is a high-pressure oil well in an oil field in the west. It was put into production in March 2020. In October, the tool string was stuck at 104m. The continuous tubing + screw drill + pump truck crude oil circulation was unblocked. The pipe string structure: 1.25″ continuous tubing + Φ38.1mm screw pump + Φ38.1mm drill bit. The continuous tubing encountered obstructions at 1041-1047m, 1382-1386m, 1473-1478m, 1612-1618m, 1772-1778m, 2405m, 2485m, and 3889, and the drill mill unblocked it. The continuous tubing was found to have lost circulation at the outlet at 2687m, and it was blocked when it was pulled up to 2238m. The obstruction was obtained. The sample brought out by the tool string looked like dry asphalt powder, which could be quickly dissolved by adding asphalt dispersant; it was flammable and would have carbon-like residues after burning, and it would flow in a fluid when burning.

[0081] The experimental analysis results of the blockage at 2260m in the well: 1) Infrared analysis showed that it was mainly asphaltene, and the composition analysis showed that the asphaltene content was 88.88%, the wax content was 5.0%, and the colloid content was 0.50%.

[0082] Table 1M-1 Well Crude Oil Density Data Table

[0083]

[0084] The first step is to determine the blockage of the high-pressure oil and gas wellbore and the depth of asphaltene precipitation

[0085] 1) Determine that asphaltene blockage has occurred in the wellbore based on the actual on-site production situation of high-pressure oil and gas wells;

[0086] 2) Determine the blockage of the wellbore of high-pressure oil and gas wells and the asphaltene precipitation depth of 3889m. The depth of the solid asphalt inhibitor should not be lower than the asphaltene precipitation depth of the wellbore. The wax precipitation depth of the wellbore is 300m deep, that is, 4189m;

[0087] Step 2: Determine the parameters of solid asphalt inhibitor

[0088] 1) Refer to Table 1, according to the density of crude oil, the density of solid asphalt inhibitor is determined to be 0.84g / cm3, the difference between the density of solid asphalt inhibitor and the density of crude oil is not less than 0.1g / cm3, and 0.95g / cm3 is selected;

[0089] 2) According to the wellbore solid asphalt inhibitor's insertion depth of 4189m and the inner diameter of the wellbore tubing corresponding to the minimum inner diameter of the shallow oil pipe of 69.89mm, the maximum outer diameter of the solid asphalt inhibitor is determined to be 50mm;

[0090] 3) According to the wellbore oil pipe string inner diameter 76mm corresponding to the wellbore solid asphalt inhibitor insertion depth, the minimum length of the solid asphalt inhibitor is determined to be 500mm;

[0091] Step 3: Ensure that the position in the wellbore where asphalt precipitates is unobstructed above the shallower part.

[0092] 1) Install a blowout preventer for wireline operations and pressure test it to 90 MPa as required and pass the test.

[0093] 2) Use wireline operations to run a wellbore cleaner to a depth of 4500 m below the depth where asphaltene precipitates in the wellbore, ensuring the tubing is unobstructed, which is beneficial for the subsequent injection of solid asphalt inhibitors. Pressure test it to 90 MPa as required and pass the test.

[0094] Step 4: Inject solid asphalt inhibitors

[0095] 1) Install a connection and injection device above the wellhead Christmas tree, with a maximum length of 20 m, and pressure test it to 90 MPa as required and pass the test.

[0096] 2) Close both the blind plug and the flat valve 6 of the wellhead injection device.

[0097] 3) Slowly open the flat valve at the bottom of the wellhead injection device to relieve the pressure of the wellhead injection device.

[0098] 4) Fill the wellhead injection device with solid asphalt inhibitors through the bottom of the wellhead injection device, a total of 15 m (30 pieces, 28 kg), and then close the bottom flat valve.

[0099] 5) Connect the wellhead injection device, open the lower flat valve 6 of the wellhead injection device and the paraffin removal valve of the Christmas tree, and the solid asphalt inhibitors will fall into the wellbore under the action of gravity.

[0100] 6) Close the paraffin removal valve of the Christmas tree, separate the wellhead injection device from the Christmas tree with the assistance of a crane, open the bottom flat valve, and fill the wellhead injection device with solid asphalt inhibitors through the bottom of the wellhead injection device.

[0101] 7) Repeat steps 4) - 6) of the solid asphalt inhibitor injection once, with a cumulative amount of 30 m (60 pieces, 56 kg), meeting the design requirements of the injection volume.

[0102] 8) Close the blind plug and the flat valve 6 of the wellhead injection device.

[0103] Step 5: Track and evaluate the on-site test effect

[0104] 1) Real-time track production data such as oil well production, oil pressure, and casing pressure, and at the same time observe whether there is any leakage at the wellhead, and determine whether asphalt plugging occurs in the oil and gas well according to the on-site production situation.

[0105] 2) Take an oil sample every 1 week to measure the crude oil asphaltene content, and evaluate the prevention and control effect and the effective period of asphalt plugging in the oil and gas well.

[0106] Step 6: Subsequent injection of solid asphalt inhibitors

[0107] 1) The injection cycle can be adjusted to 60 days according to production data and experimental test results on-site. The long-term stable production of the wellbore blocked by asphaltene can be achieved through the process of regularly injecting solid asphaltene inhibitor at the wellhead.

[0108] 2) The solid asphaltene inhibitor has adaptability and a valid period. It needs to be regularly injected in combination with the actual situation of a single well. Before the next injection, the wellbore needs to be circulated to ensure it is unobstructed before injecting, to avoid ineffective injection caused by the solid asphaltene inhibitor failing to reach the designated depth in the wellbore.

[0109] A method for injecting solid asphaltene inhibitor at the wellhead disclosed in this application first determines whether asphaltene blockage occurs in the wellbore based on the actual on-site production situation of high-pressure oil and gas wells, judges the blockage situation of the high-pressure oil and gas wellbore and the asphaltene precipitation depth, determines the parameters of the solid asphaltene inhibitor, ensures the smoothness of the wellbore above the asphaltene precipitation position through measures, places the wellhead injection device at the upper end of the paraffin removal valve of the Christmas tree through a crane, fills the solid asphaltene inhibitor into it through the bottom of the wellhead injection device, and closes the bottom flat valve. Connect the wellhead injection device, close both its blind plug and flat valve, open the lower flat valve of the wellhead injection device and the paraffin removal valve of the Christmas tree, and the solid asphaltene inhibitor falls into the wellbore under the action of gravity. Close the paraffin removal valve of the Christmas tree, separate the wellhead injection device from the Christmas tree with the assistance of a crane, open the bottom flat valve, fill the solid asphaltene inhibitor into it through the bottom of the wellhead injection device, and repeat the steps of injecting the solid asphaltene inhibitor until the injection volume meets the design requirements. Real-time track production data such as the oil well output, oil pressure, and casing pressure, and at the same time observe whether there is any leakage at the wellhead, and determine whether asphaltene blockage occurs in the oil and gas well according to the on-site production situation; take an oil sample at regular intervals to conduct the determination of the crude oil asphaltene content, and evaluate the prevention and control effect and the valid period of the asphaltene blockage in the oil and gas well. The injection cycle can be adjusted according to production data and experimental test results on-site, and the long-term stable production of the wellbore blocked by asphaltene can be achieved through the process of regularly injecting solid asphaltene inhibitor at the wellhead.

[0110] The above content is only to illustrate the technical idea of the present invention and cannot be used to limit the protection scope of the present invention. Any modification made on the basis of the technical solution according to the technical idea proposed by the present invention falls within the protection scope of the claims of the present invention.

Claims

1. A solid asphalt inhibitor wellhead injection device, characterized in that: The utility model comprises an injection pipe column (2), wherein a blind plug (1) is arranged at the upper end of the injection pipe column (2), a flat valve (6) is fixedly connected at the lower end, and the lower end of the flat valve (6) is connected to a wax removal valve (9) on an oil production tree (8).

2. A solid asphalt inhibitor wellhead injection device according to claim 1, characterized in that: The injection column (2) is also provided with a pressure gauge (7) for safety pressure testing.

3. A solid asphalt inhibitor wellhead injection device according to claim 1, characterized in that: The upper end of the injection pipe column (2) is connected to the blind plug (1) via a thread.

4. A solid asphalt inhibitor wellhead injection device according to claim 1, characterized in that: The lower end of the injection column (2) is fixedly connected to the flat valve (6) through the flange (3) and the flange plate (5).

5. A solid asphalt inhibitor wellhead injection device according to claim 1, characterized in that: The flat valve (6) is connected to the wax removal valve (9) on the Christmas tree (8) via a thread or a reducing flange.

6. A solid asphalt inhibitor wellhead injection device according to claim 1, characterized in that: Its length shall not exceed 20m.

7. A method for injecting a solid asphalt inhibitor wellhead injection device based on any one of claims 1 to 6, characterized in that: The following steps are involved: Determine the blockage of high-pressure oil and gas wells and the depth of asphaltene precipitation to determine the depth of solid asphalt inhibitors in the wellbore; Determine the parameters of the solid asphalt inhibitor according to the depth of the solid asphalt inhibitor in the wellbore; Filling the solid asphalt inhibitor in the injection device according to the determined parameters of the solid asphalt inhibitor; Inject solid asphalt inhibitors and track oil well production data in real time to determine whether asphaltene blockage occurs in the oil and gas well.

8. A method for injecting solid asphalt inhibitor into a wellhead according to claim 7, characterized in that: After determining the depth of the solid asphalt inhibitor in the wellbore, it is also necessary to ensure that the asphalt precipitation location in the wellbore is shallow and unobstructed.

9. A method for injecting solid asphalt inhibitor into a wellhead according to claim 7, characterized in that: Determining the parameters of the solid asphalt inhibitor according to the depth of the solid asphalt inhibitor in the wellbore specifically includes the following steps: S201: Determine the density of the solid asphalt inhibitor according to the density of the crude oil, and the difference between the density of the solid asphalt inhibitor and the density of the crude oil is not less than 0.1 g / cm3; S202: Determine the maximum outer diameter of the solid asphalt inhibitor according to the inner diameter of the wellbore oil pipe string corresponding to the depth of the wellbore solid asphalt inhibitor, and the difference between the outer diameter and the inner diameter of the shallow oil pipe at the wellbore asphaltene precipitation depth is not less than 5 mm; S203: Determine the minimum length of the solid asphalt inhibitor according to the inner diameter of the wellbore tubing corresponding to the depth of the wellbore solid asphalt inhibitor being lowered, and the length shall not be less than 3 times the inner diameter of the shallow tubing at the wellbore asphaltene precipitation depth.

10. A method for injecting solid asphalt inhibitor into a wellhead according to claim 7, characterized in that: Filling a solid asphalt inhibitor in an injection device specifically includes the following steps: S301: Install a wellhead injection device on the upper part of the wellhead Christmas tree (8) and pass the pressure test; S302: Close the blind plug (1) and the flat valve (6) of the wellhead injection device; S303: slowly open the flat valve (6) at the bottom of the wellhead injection device to relieve the pressure of the wellhead injection device; S304: Fill the solid asphalt inhibitor into the bottom of the wellhead injection device, close the flat valve (6) at the bottom; connect the wax removal valve (9) on the Christmas tree (8); When injecting the solid asphalt inhibitor, the flat valve (6) and the wax removal valve (9) are opened, and the solid asphalt inhibitor falls into the wellbore under the action of gravity.

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