High-pressure oil and gas well anti-scaling device based on underground continuous filling and mounting method

Abstract

The invention belongs to the technical field of oil field scale prevention, and provides a high-pressure oil and gas well scale prevention device based on underground continuous filling and an installation method, and the high-pressure oil and gas well scale prevention device comprises a penetrable packer, a capillary tube, an oil tube, a sleeve and a ground unit; the oil pipe is positioned in the sleeve; the casing pipe extends to an underground oil reservoir from the ground; and the penetrating packer is arranged in an annular space between the oil pipe and the sleeve. According to the device, the capillary tube is tripped into the well by modifying the packer and the tubing hanger, quantitative, accurate and continuous filling of the scale inhibitor of the well with the packer is achieved in combination with a ground dosing system, the capillary tube blocking risk is reduced by configuring the high-pressure filter and the device material selection and agent screening process, and meanwhile, the service life of the capillary tube is prolonged. By adopting the single-flow filling head and the check valve, the problem of scale inhibitor backflow possibly caused by high pressure of a gas well is solved, the reliability of the device is ensured through the synergistic effect of the aspects, the scale prevention problem of a high-pressure oil and gas well shaft is solved, and efficient and safe production of an oil field is ensured.

Description

Technical Field

[0001] The invention belongs to the technical field of oilfield anti-scaling, and in particular relates to a high-pressure oil and gas well anti-scaling device based on downhole continuous injection and an installation method. Background Art

[0002] Scaling seriously impacts the integrity of oil and gas wellbores, potentially leading to reduced oil and gas production, under-scale corrosion, and even threatening the safety of wellbores and surface facilities. Oil and gas field scale is categorized into organic and inorganic scale. Common organic scale includes asphaltenes, waxes, and colloids, while common inorganic scale primarily includes calcium, magnesium, barium, strontium, and iron salts. The higher the colloid, asphaltenes, and wax content in the oil product and the lower the temperature, the greater the risk of organic scale formation. Higher water mineralization and the higher the content of calcium, magnesium, barium, strontium, iron, and sulfate ions increase the tendency for inorganic scale formation.

[0003] The cost of descaling a single well is high, and downtime losses are even greater. Maintaining healthy well production is the most effective way to ensure normal oil and gas production. Current major anti-scaling technologies include strong magnetic anti-scaling, electric field anti-scaling, anti-scaling agents, and anti-scaling coatings. Strong magnetic and electric field anti-scaling methods are limited by device size and are not suitable for downhole environments. Anti-scaling coatings require complete tubing replacement, which is uneconomical. Furthermore, the coatings experience performance degradation after exposure to the downhole environment, potentially posing a serious corrosion risk. Chemical anti-scaling agents are currently the most ideal method for wellbore scale prevention. However, the bottleneck of downhole chemical anti-scaling lies in the agent injection method. Current chemical anti-scaling agent injection methods include solid anti-scaling blocks, continuous annular injection, and squeeze injection. The solid anti-scaling block method involves placing a solid anti-scaling agent in the working barrel. As the liquid passes through the anti-scaling block, the anti-scaling agent dissolves in the liquid, acting as a scale preventer. This method is cost-effective, but the dissolution rate of the anti-scaling block is difficult to control. The continuous annular injection method involves periodically dripping a chemical antiscalant into the annular space of the oil well casing. While its advantage is its effective antiscaling effect, its disadvantages are that continuous dosing can sometimes be difficult due to winter freezing and human factors. Furthermore, injection into the tubing can be difficult when a packer is present. The squeeze injection method involves squeezing the antiscalant into the formation, allowing it to fully absorb into the rock. The basic principle is to inject a large dose of a low-concentration antiscalant solution through the wellhead into the perforations and deep within the formation, relying on the antiscalant's adsorption on the rock surface to retain it in the formation pores. However, this method is difficult to control the dosing concentration, requires a high level of chemical, and is complex to operate. Regular squeeze injection is required, impacting production. Summary of the Invention

[0004] In order to solve at least one problem in the background technology, the present invention provides a high-pressure oil and gas well anti-scaling device based on downhole continuous injection and an installation method.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A high-pressure oil and gas well anti-scaling device based on downhole continuous injection, comprising a traversable packer, a capillary tube, an oil pipe, a casing and an uphole unit;

[0007] The oil pipe is located in the casing;

[0008] The casing extends from the surface to the underground oil reservoir;

[0009] The crossing packer is arranged in the annulus between the tubing and the casing;

[0010] One end of the capillary tube passes through the penetration packer and extends to the lower end of the casing, and a one-way chemical injection head is installed at the end;

[0011] The capillary tube extends to the ground surface and is connected to the uphole unit;

[0012] The above-the-hole unit is used for storing the antiscalant and controlling the flow rate when the antiscalant is added.

[0013] Preferably, a fixer is further installed on the oil pipe, and the fixer is used to fix the capillary tube.

[0014] Preferably, a traversable tubing hanger is installed on the top of the tubing, and the capillary tube passes through the traversable tubing hanger and is connected to the uphole unit.

[0015] Preferably, the uphole unit comprises a first needle valve, a check valve, a high-pressure filter, a pressure gauge, a second needle valve, a metering plunger pump and an antiscalant storage tank connected in sequence;

[0016] One end of the first needle valve away from the check valve is connected to the capillary tube.

[0017] Preferably, an agitator is installed in the antiscalant storage tank.

[0018] An installation method for the above-mentioned high-pressure oil and gas well anti-scaling device based on downhole continuous injection comprises the following steps:

[0019] Configure antiscalant;

[0020] Select the wellhead unit, capillary tube and one-way chemical injection head that are compatible with the scale inhibitor;

[0021] Determine the injection flow rate and pumping pressure of the antiscalant;

[0022] Unseal the original packer, remove it, and replace it with a crossing packer;

[0023] Install the capillary tube and install a one-way chemical injection head at one end of the capillary tube;

[0024] Connect the other end of the capillary to the well unit.

[0025] Preferably, preparing the antiscalant comprises the following steps:

[0026] Obtain downhole scale type, water quality and temperature;

[0027] Screening of antiscalant formulations based on scale type, water quality and temperature;

[0028] The cleanliness of the scale inhibitor is tested and it is qualified if the cleanliness meets the requirement of no more than level 10.

[0029] Preferably, installing the capillary tube comprises the following steps:

[0030] Use 5000psi nitrogen to test the capillary tube pressure. After ensuring there is no blockage or leakage, pass the end of the capillary tube through the through hole of the packer and seal it.

[0031] Install a one-way chemical injection head at the end of the capillary;

[0032] Use a holder to fix the capillary tube to one side of the tubing;

[0033] Run the oil tubing and capillary tube into the casing simultaneously;

[0034] After reaching the bottom of the well, the capillary is cut off and passed through the traversable tubing hanger and sealed.

[0035] Preferably, connecting the other end of the capillary tube to the uphole unit comprises the following steps:

[0036] Connect the capillary tube to the first needle valve, check valve, high-pressure filter, pressure gauge, second needle valve, metering plunger pump and antiscalant storage tank in sequence.

[0037] Beneficial effects of the present invention:

[0038] The device of the present invention lowers the capillary into the well by modifying the packer and the oil pipe hanger, and combines with the ground dosing system to realize the quantitative, accurate and continuous injection of scale inhibitors in the well with the packer. The risk of capillary blockage is reduced by configuring a high-pressure filter and the device material selection and drug screening process. At the same time, the use of a single-flow filling head and a check valve eliminates the problem of scale inhibitor backflow caused by the high pressure of the gas well. Through the synergistic effect of the above aspects, the reliability of the device is guaranteed, the problem of scale prevention in the wellbore of high-pressure oil and gas wells is solved, and the efficient and safe production of the oil field is guaranteed.

[0039] Other features and advantages of the present invention will be described in the following description, and in part will become apparent from the description, or will be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0041] Figure 1 A schematic structural diagram of a high-pressure oil and gas well anti-scaling device based on downhole continuous injection according to the present invention is shown;

[0042] Figure 2 Shown is the installation flow chart of the high-pressure oil and gas well anti-scaling device.

[0043] In the figure: 1. Traversable packer; 2. Capillary tube; 3. One-way chemical injection head; 4. Fixer; 5. Oil pipe; 6. Traversable oil pipe hanger; 7. First needle valve; 8. Check valve; 9. High-pressure filter; 10. Pressure gauge; 11. Second needle valve; 12. Metering plunger pump; 13. Antiscalant storage tank; 14. Agitator; 15. Oil reservoir; 16. Casing. DETAILED DESCRIPTION

[0044] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0045] Example 1

[0046] A high-pressure oil and gas well anti-scaling device based on downhole continuous injection, such as Figure 1 As shown, the system comprises a traversable packer 1, a capillary tube 2, an oil pipe 5, a casing 16, and an uphole unit. The oil pipe 5 is located within the casing 16, with an annular space between them. The casing 16 extends from the surface to the underground reservoir 15. The traversable packer 1 is fixedly installed in the annulus between the oil pipe 5 and the casing 16. One end of the capillary tube 2 extends through the traversable packer 1 to the lower end of the casing 16, and a one-way chemical injection head 3 is installed at the end. The other end of the capillary tube 2 extends to the surface and connects to the uphole unit. The uphole unit is used to store the scale inhibitor and control the flow rate during the injection of the scale inhibitor.

[0047] Furthermore, a fixture 4 is installed on the oil pipe 5, and the fixture 4 is used to fix the capillary tube 2. Moreover, a traversable oil pipe hanger 6 is installed on the top of the oil pipe 5, and the capillary tube 2 passes through the traversable oil pipe hanger 6 and is connected to the uphole unit.

[0048] The uphole unit further includes a first needle valve 7, a check valve 8, a high-pressure filter 9, a pressure gauge 10, a second needle valve 11, a metering plunger pump 12, and an antiscalant tank 13, which are connected in sequence. The end of the first needle valve 7 away from the check valve 8 is connected to the capillary tube 2. The antiscalant tank 13 is equipped with an agitator 14.

[0049] It should be noted that the operation process of the device in Example 1 is as follows: the scale inhibitor that has passed the test is stored in the scale inhibitor storage tank 13, and the agitator 14 is turned on; the first needle valve 7 and the second needle valve 11 are opened; the flow rate of the metering plunger pump 12 is calculated and set according to the gas well production and the scale inhibitor injection concentration, and the metering plunger pump 12 is turned on; the scale inhibitor is injected into the oil reservoir 15 in sequence through the scale inhibitor storage tank 13, the metering plunger pump 12, the second needle valve 11, the high-pressure filter 9, the check valve 8, the first needle valve 7, the capillary 2 and the one-way chemical injection head 3; finally, the scale inhibitor reacts with the medium in the oil reservoir 15 to achieve the purpose of scale inhibition.

[0050] It should be noted that this device, while primarily designed for high-pressure oil and gas wells, can also be applied to conventional oil and gas wells. By modifying the downhole packer and wellhead tubing hanger, a capillary tube 2 is lowered into the annulus between the tubing 5 and the casing 16, and in conjunction with a surface scale inhibitor metering system, this method provides wellbore scale prevention. This device overcomes the challenges of injecting chemicals into wellbores with packers, resolving the difficulties of injecting chemicals into conventional high-pressure oil and gas wells with packers, such as difficulty, poor results, uncontrollable dosing, and clogging and fluid return, thereby improving wellbore scale prevention in oil and gas fields.

[0051] Furthermore, the device takes into account the relatively small diameter of the capillary tube 2, employing a high-pressure filter 9 and a process for selecting materials and selecting reagents to ensure reliability and reduce the risk of clogging. Furthermore, the present invention addresses the issue of excessive pressure in high-pressure oil and gas wells by employing a one-way chemical injection head 3 and a check valve 8 to prevent scale inhibitor backflow.

[0052] Example 2

[0053] An installation method such as Figure 2 As shown, a high-pressure oil and gas well anti-scaling device based on downhole continuous injection used in Example 1 includes the following steps: S1: preparing a scale inhibitor; S2: selecting an uphole unit, a capillary tube 2, and a one-way chemical injection head 3 that are compatible with the scale inhibitor; S3: determining the injection flow rate and pumping pressure of the scale inhibitor; S4: unsealing the original packer, removing it, and replacing it with the through packer 1;

[0054] S5: Install the capillary tube 2 and install the one-way chemical injection head 3 at one end of the capillary tube 2; S6: Connect the other end of the capillary tube 2 to the uphole unit.

[0055] Furthermore, when configuring the scale inhibitor, the following steps are specifically included:

[0056] Obtain the scale type, water quality and temperature downhole, then screen the scale inhibitor formula based on the scale type, water quality and temperature. Then test the cleanliness of the scale inhibitor. If the cleanliness meets the requirements of no more than level 10, it is qualified. The cleanliness is in accordance with the SAE AS4059 standard.

[0057] Furthermore, installing the capillary tube 2 comprises the following steps:

[0058] The capillary tube 2 is pressure-tested with 5000 psi nitrogen to ensure it is free of blockage and leakage. The end of the capillary tube 2 is then passed through the through-hole of the through-packer 1 and sealed. A one-way chemical injection head 3 is installed at the end of the capillary tube 2. The capillary tube 2 is secured to one side of the tubing 5 using a retainer 4. The tubing 5 and the capillary tube 2 are then simultaneously lowered into the casing 16. Once at the bottom of the well, the capillary tube 2 is cut and passed through the traversable tubing hanger 6 and sealed.

[0059] Furthermore, the other end of the capillary 2 is connected to the uphole unit, which specifically includes the following steps: connecting the capillary 2 to the first needle valve 7, the check valve 8, the high-pressure filter 9, the pressure gauge 10, the second needle valve 11, the metering plunger pump 12 and the scale inhibitor storage tank 13 in sequence.

[0060] Finally, after passing the test, the scale inhibitor is continuously injected, and the scale inhibitor formula and injection flow rate are adjusted according to the feedback of the downhole scaling condition.

[0061] It should be noted that the above method achieves continuous downhole scale inhibitor injection in high-pressure oil and gas wells equipped with packers. Furthermore, by fully considering issues such as bottomhole high pressure, agent particle size, and key component materials, it avoids backflow, blockage, and corrosion in the capillary tube 2 injection system, ensuring the reliability and safety of the scale inhibitor injection system. Finally, compared with the solid anti-scaling block method, this method achieves controllable and adjustable scale inhibitor injection concentration. Compared with the traditional annular continuous injection method, this method achieves continuous downhole scale inhibitor injection in high-pressure oil and gas wells equipped with packers. Compared with the squeeze injection method, the scale inhibitor release rate is more controllable, with less impact on production and better economic efficiency.

[0062] Example 3

[0063] The formation water in an oilfield is of poor quality and high salinity. The fluid is prone to inorganic and organic scaling as it flows through the perforations and wellbores. Since the start of production, scaling has been a problem in several producing wells in this oilfield. The scale is primarily composed of organic and acid-soluble inorganic scale. Due to the presence of a packer in the wellbore, traditional scale prevention methods are difficult to apply. A capillary continuous injection scale prevention device was installed in a scaling well in this oilfield.

[0064] (1) First, based on the scale type, water quality, and temperature analysis, select the appropriate scale inhibitor formula and test the cleanliness of the candidate scale inhibitor. The cleanliness level must not exceed level 10 to prevent capillary blockage.

[0065] (2) Carry out material selection for key components of the continuous filling system of capillary tube 2, evaluate the compatibility of capillary tube 2, one-way chemical injection head 3, first needle valve 7, check valve 8, high-pressure filter 9, second needle valve 11 and metering plunger pump 12 with candidate antiscalants, and determine to use 304L stainless steel as the material of the above key components;

[0066] (3) Determine the injection flow rate of the scale inhibitor based on the scale inhibitor laboratory evaluation results and the production of the well, and calculate the flow resistance of the scale inhibitor in the capillary tube 2 based on the relevant parameters of the well to determine the pumping pressure of the metering plunger pump 12;

[0067] (4) Unseal the original packer, remove it, and replace it with the crossing packer 1;

[0068] (5) Use 5000psi nitrogen to test the capillary 2. After ensuring that there is no blockage or leakage, pass the end of the capillary 2 through the through hole of the packer 1 and seal it. Here, a capillary with a diameter of 1 / 4" and made of 304L stainless steel is selected;

[0069] (6) A one-way chemical injection head 3 is installed at the end of the capillary tube 2. Here, a one-way chemical injection head 3 with a 3 / 8" interface, an outer diameter of 1", a length of 7.5", a working pressure of 10,000 psi, and a material of 304L stainless steel is selected;

[0070] (7) Use the fixture 4 to fix the injection head and the capillary tube 2 to one side of the oil pipe 5; lower the oil pipe 5 and the capillary tube 2 together into the wellbore casing 16;

[0071] (8) After reaching the bottom of the well, reserve enough length of capillary tube 2, cut the capillary tube 2, pass it through the passable oil pipe hanger 6, and seal it;

[0072] (9) Capillary tube 2 is sequentially connected to the first needle valve 7, check valve 8, high-pressure filter 9, pressure gauge 10, second needle valve 11, metering plunger pump 12, and antiscalant tank 13, and used after testing. The high-pressure filter 9 selected here has a rated working pressure of 5000 psi, the check valve 8 has a rated working pressure of 5000 psi, the pressure gauge has a range of 0-5000 psi, and the metering plunger pump 12 has a plunger stroke length of 0.6", a plunger size of 1 / 4", a rated working pressure of 5000 psi, and is explosion-proof certified and solar-powered.

[0073] After passing the test, the scale inhibitor is continuously injected. During the injection process, the scale inhibitor formula and injection flow rate can be adjusted according to the feedback of the downhole scaling condition.

[0074] Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high-pressure oil and gas well anti-scaling device based on downhole continuous injection, characterized in that: It includes a traversable packer (1), a capillary tube (2), an oil pipe (5), a casing (16) and an uphole unit; The oil pipe (5) is located in the casing (16); The casing (16) extends from the surface to the underground oil reservoir (15); The crossing packer (1) is arranged in the annulus between the oil pipe (5) and the casing (16); One end of the capillary tube (2) passes through the penetration packer (1) and extends to the lower end of the casing (16), and a one-way chemical injection head (3) is installed at the end; The capillary tube (2) extends to the ground surface and is connected to the uphole unit; The above-the-hole unit is used for storing the antiscalant and controlling the flow rate when the antiscalant is added.

2. A high-pressure oil and gas well anti-scaling device based on downhole continuous injection according to claim 1, characterized in that: A fixer (4) is also installed on the oil pipe (5), and the fixer (4) is used to fix the capillary tube (2).

3. A high-pressure oil and gas well anti-scaling device based on downhole continuous injection according to claim 2, characterized in that: A traversable oil pipe hanger (6) is installed on the top of the oil pipe (5), and the capillary tube (2) passes through the traversable oil pipe hanger (6) and is connected to the uphole unit.

4. The high-pressure oil and gas well anti-scaling device based on downhole continuous injection according to claim 1 is characterized in that: The uphole unit comprises a first needle valve (7), a check valve (8), a high-pressure filter (9), a pressure gauge (10), a second needle valve (11), a metering plunger pump (12) and an antiscalant storage tank (13) which are connected in sequence; One end of the first needle valve (7) away from the check valve (8) is connected to the capillary tube (2).

5. A high-pressure oil and gas well anti-scaling device based on downhole continuous injection according to claim 4, characterized in that: An agitator (14) is installed in the antiscalant storage tank (13).

6. An installation method, characterized in that: A high-pressure oil and gas well anti-scaling device based on downhole continuous injection, used in any one of claims 1-5.

7. An installation method according to claim 6, characterized in that: The following steps are involved: Configure antiscalant; Selecting an uphole unit, a capillary tube (2) and a one-way chemical injection head (3) that are compatible with the scale inhibitor; Determine the injection flow rate and pumping pressure of the antiscalant; Unseal the original packer, remove it, and replace it with the crossing packer (1); Installing a capillary tube (2), and installing a one-way chemical injection head (3) at one end of the capillary tube (2); Connect the other end of the capillary (2) to the well unit.

8. An installation method according to claim 7, characterized in that: The preparation of antiscalant includes the following steps: Obtain downhole scale type, water quality and temperature; Screening of antiscalant formulations based on scale type, water quality and temperature; The cleanliness of the scale inhibitor is tested and it is qualified if the cleanliness meets the requirement of no more than level 10.

9. The installation method according to claim 7, characterized in that: Installing the capillary tube (2) comprises the following steps: The capillary tube (2) is pressure tested with 5000 psi nitrogen to ensure that there is no blockage or leakage, and then the end of the capillary tube (2) is passed through the through hole of the packer (1) and sealed; A one-way chemical injection head (3) is installed at the end of the capillary tube (2); Use a holder (4) to fix the capillary tube (2) to one side of the oil tube (5); Lower the oil pipe (5) and the capillary tube (2) into the casing (16) simultaneously; After reaching the bottom of the well, the capillary tube (2) is cut off and passed through the traversable oil pipe hanger (6) and sealed.

10. The installation method according to claim 7, characterized in that: Connecting the other end of the capillary tube (2) to the well unit includes the following steps: The capillary tube (2) is sequentially connected to the first needle valve (7), the check valve (8), the high-pressure filter (9), the pressure gauge (10), the second needle valve (11), the metering plunger pump (12) and the antiscalant storage tank (13).

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