Oil and gas pipeline cleaning device and method based on ice slurry

Abstract

The invention belongs to the technical field of oil and gas pipeline cleaning based on ice slurry, and particularly relates to an oil and gas pipeline cleaning device and method based on ice slurry, and the method comprises the steps that a first main valve and a second main valve are closed, a ball serving valve and a ball receiving valve are opened, and ice slurry is injected into a to-be-cleaned pipeline; the injected ice slurry is metered through a flow meter, and when the ice slurry with the preset flow is injected, injection of the ice slurry is completed; opening a ball serving barrel oil inlet valve and a ball receiving barrel oil outlet valve, adjusting the opening degree of the ball serving barrel oil inlet valve according to the ice slurry melting rate and the shearing stress, and controlling the ice slurry pigging speed; when the ice slurry reaches the ball receiving barrel, the inlet valve of the waste liquid tank is opened, the oil outlet valve of the ball receiving barrel is closed, and the ice slurry after pipe cleaning enters the waste liquid tank.

Description

Technical Field

[0001] The present invention belongs to the technical field of oil and gas pipeline cleaning based on ice slurry, and in particular relates to an oil and gas pipeline cleaning device and method based on ice slurry. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] During the long-term operation of oil and gas pipelines, the accumulation of impurities will lead to a decrease in transportation efficiency, and regular cleaning is required. Currently, commonly used cleaning devices include mechanical cleaning devices, polyurethane foam cleaning devices, and gel cleaning devices, but these cleaning devices have certain limitations. The mechanical cleaning device can be prevented from getting stuck by evaluating its passing performance, but its universality between different oil and gas pipelines is poor; polyurethane foam cleaning devices can solve the problem of blocking by fracturing, but the residues of the cleaning devices affect production; when gel composite cleaning devices are used, cleaning requires the use of other equipment and the shear stress at the pipe wall is small.

[0004] According to the inventors, ice slurry pipe cleaning technology is a new type of pipe cleaning method. It uses ice slurry composed of ice particles, liquid water and freezing point inhibitors. Under the push of the original medium in the pipe, the ice slurry collides with the pipe wall to discharge impurities from the oil and gas pipeline, and can use its own fluidity and melting characteristics to solve the problem of pipe cleaning device blockage. How to set ice slurry pipe cleaning parameters in combination with the actual working conditions of the oil and gas pipeline is a difficult problem that needs to be solved urgently. Summary of the invention

[0005] To solve the above problems, the present invention proposes an oil and gas pipeline cleaning device and method based on ice slurry, which determines the ice slurry pipeline cleaning parameter range according to the pipeline impurity removal requirements and the ice slurry melting characteristics, prepares ice slurry according to the determined ice slurry pipeline cleaning parameter range, and combines the improved ice slurry based oil and gas pipeline cleaning device to efficiently clean the oil and gas pipeline.

[0006] According to some embodiments, a first solution of the present invention provides a method for preparing ice slurry, using the following technical solution:

[0007] A method for preparing ice slurry, comprising:

[0008] Obtain pipeline parameters of the oil and gas pipeline to be cleaned;

[0009] Calculate the melting rate of ice slurry in the oil and gas pipeline to be cleaned according to the obtained pipeline parameters;

[0010] Combined with the obtained melting rate of ice slurry, the shear stress of ice slurry at the end of the pipeline to be cleaned is calculated;

[0011] Based on the obtained shear stress, the ice slurry cleaning parameters are determined to complete the preparation of the ice slurry.

[0012] As a further technical limitation, the obtained pipeline parameters include at least the pipeline ambient temperature, diameter, length, wall thickness, pipe wall material, insulation material and pipe wall impurities; the pipe outer wall temperature is set to the ambient temperature, and the changes in the pipe wall temperature and the ice slurry temperature during the entire pipe cleaning process are calculated based on the pipeline related parameters, initial ice fraction, initial ice slurry volume and pipe cleaning speed; the ice slurry melting rate is calculated based on the difference between the pipeline ambient temperature and the ice slurry temperature, and the melting rate under different ice fractions and pipe cleaning speeds is obtained.

[0013] Furthermore, the melting rate obtained under different conditions during the ice slurry cleaning process is used to calculate the change in ice fraction during the cleaning process, and the change in ice fraction along the pipeline is obtained; the ice slurry shear stress is calculated based on the particle size, ice fraction and cleaning speed, and the change in shear stress along the pipeline is obtained.

[0014] Furthermore, the shear stress value at the end of the pipeline is calculated based on the obtained change in ice slurry shear stress and compared with the minimum shear stress required to remove impurities from the pipe wall. If the shear stress at the end of the ice slurry is greater than the minimum shear stress required to remove impurities from the pipe wall, the ice slurry particle size, ice fraction, ice slurry volume and pipe cleaning speed at this time are used as ice slurry pipe cleaning parameters.

[0015] According to some embodiments, a second solution of the present invention provides an oil and gas pipeline cleaning device based on ice slurry, which adopts the following technical solution:

[0016] An oil and gas pipeline cleaning device based on ice slurry, comprising an ice slurry component, a ball-serving component, a pipeline to be cleaned, a ball-receiving component and a waste liquid component which are connected in sequence; wherein the ice slurry component comprises an ice slurry storage tank for placing ice slurry prepared by the ice slurry preparation method provided in the first scheme and a flowmeter for measuring the ice slurry flow rate; the ball-serving component comprises a ball-serving barrel, a ball-serving valve, a ball-serving barrel oil inlet valve, a first main valve and an upstream of the pipeline to be cleaned, one end of the upstream of the pipeline to be cleaned is connected to the ball-serving barrel oil inlet valve and the first main valve, the ball-serving barrel and the ball-serving valve are connected in series, and the other ends of the ball-serving barrel oil inlet valve and the first main valve are connected to the ball-serving barrel and the ball-serving barrel, respectively. Valve; the ball collecting assembly includes a ball collecting cylinder, a ball collecting valve, a ball collecting cylinder oil outlet valve, a second main valve and a downstream of the pipeline to be cleaned, one end of the downstream of the pipeline to be cleaned is connected to the ball collecting cylinder oil outlet valve and the second main valve, the ball collecting cylinder and the ball collecting valve are connected in series, and the other ends of the ball collecting cylinder oil outlet valve and the second main valve are connected to the ball collecting cylinder and the ball collecting valve respectively; one end of the pipeline to be cleaned is connected to the ball sending valve and the first main valve, and the other end is connected to the ball receiving valve and the second main valve; the waste liquid assembly includes a waste liquid tank inlet valve and a waste liquid tank, one end of the waste liquid tank inlet valve is connected to the ball collecting cylinder away from the pipeline to be cleaned, and the other end is connected to the waste liquid tank.

[0017] As a further technical limitation, an ice slurry storage tank outlet valve, a volumetric pump, a volumetric pump outlet pressure gauge and a volumetric pump outlet valve are sequentially arranged between the ice slurry storage tank and the flow meter; a ball launching cylinder quick-opening blind plate is arranged at the end of the ball launching cylinder near the flow meter side; and a ball receiving cylinder quick-opening blind plate is arranged at the end of the ball receiving cylinder near the waste liquid tank inlet valve side.

[0018] As a further technical limitation, the ball serving cylinder is provided with a ball serving cylinder bypass valve, a ball serving cylinder pressure gauge and a ball serving indicator in sequence; the ball receiving cylinder is provided with a ball receiving cylinder bypass valve, a ball receiving cylinder pressure gauge and a ball passing indicator in sequence; the ball receiving cylinder is provided with a first sewage valve and a second sewage valve, and the other end of the first sewage valve is connected to the other end of the second sewage valve.

[0019] According to some embodiments, the third solution of the present invention provides an oil and gas pipeline cleaning method based on ice slurry, which adopts the oil and gas pipeline cleaning device based on ice slurry provided by the second solution, and adopts the following technical solutions:

[0020] An oil and gas pipeline cleaning method based on ice slurry, comprising:

[0021] Close the first main valve and the second main valve, open the ball valve and the ball valve, and inject ice slurry into the pipeline to be cleaned;

[0022] The injected ice slurry is measured by a flow meter, and when the preset flow rate of ice slurry is injected, the injection of the ice slurry is completed;

[0023] Open the oil inlet valve of the ball launching cylinder and the oil outlet valve of the ball collecting cylinder, adjust the opening of the oil inlet valve of the ball launching cylinder according to the melting rate of the ice slurry and the shear stress, and control the ice slurry pipe cleaning speed; when the ice slurry reaches the ball collecting cylinder, open the inlet valve of the waste liquid tank, close the oil outlet valve of the ball collecting cylinder, and the ice slurry after pipe cleaning enters the waste liquid tank.

[0024] As a further technical limitation, an oil and gas pipeline cleaning method based on ice slurry also includes pipe cleaning effect detection. Specifically, according to the time when the ice slurry reaches the ball collecting barrel and the time when the ice slurry is completely removed, the same time interval is set, the first drain valve and the second drain valve are opened multiple times to collect ice slurry samples, and the residual amount in the ice slurry sample is collected and detected to judge the ice slurry pipe cleaning effect.

[0025] Furthermore, according to the pipeline material parameters, the temperature difference between the pipe wall and the ice slurry, and the ice fraction, the change in ice slurry length along the pipe length is calculated to obtain the ice slurry length at the end of the pipe. The time it takes for the ice slurry to reach the ball collecting barrel is obtained by the ratio of the difference between the pipe length and the ice slurry length at the end to the pipe cleaning speed. The time it takes for the ice slurry to be completely discharged from the ball collecting barrel is obtained according to the ratio of the pipeline length to the pipe cleaning speed.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The present invention optimizes the ice slurry cleaning parameters and combines the original medium pressure in the oil and gas pipeline to make the ice slurry shear stress greater than the impurity adhesion force, thereby improving the cleaning effect. Due to the melting property of ice slurry, when a blockage occurs, the ice slurry can be discharged by melting, without causing damage to the pipeline and equipment, significantly reducing the risk of accidents.

[0028] The present invention utilizes the original ball receiving device and ball launching device of the oil and gas pipeline device for improvement, does not require additional large-scale equipment investment, and significantly reduces the cost of cleaning the pipeline. The ice slurry melts into water after the cleaning is completed, and will not cause pollution to the environment after being discharged from the pipeline. Compared with the traditional cleaning technology, the present invention is cleaner and more environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The drawings in the specification that constitute a part of this embodiment are used to provide a further understanding of this embodiment. The schematic embodiments of this embodiment and their descriptions are used to explain this embodiment and do not constitute improper limitations on this embodiment.

[0030] Figure 1 is a flow chart of the ice slurry preparation method in Example 1 of the present invention;

[0031] Figure 2 This is a schematic structural diagram of an oil and gas pipeline cleaning device based on ice slurry in Embodiment 2 of the present invention;

[0032] Figure 3 This is a flow chart of an oil and gas pipeline cleaning method based on ice slurry in Embodiment 3 of the present invention;

[0033] Figure 4 This is a schematic diagram of cleaning an oil and gas pipeline with ice slurry in Embodiment 3 of the present invention;

[0034] Among them, 1. Ice slurry storage tank; 2. Ice slurry storage tank outlet valve; 3. Volumetric pump; 4. Volumetric pump outlet pressure gauge; 5. Volumetric pump outlet valve; 6. Flow meter; 7. Ball serving cylinder quick-opening blind plate; 8. Ball serving cylinder; 9. Ball serving valve; 10. Ball serving cylinder oil inlet valve; 11. Ball serving cylinder bypass valve; 12. Ball serving cylinder pressure gauge; 13. Ball serving indicator; 14. First main valve; 15. Second main valve; 16. Pipeline to be cleaned; 17. Ball receiving cylinder oil outlet valve; 18. Ball passing indicator; 19. Ball receiving cylinder pressure gauge; 20. Ball receiving cylinder bypass valve; 21. Ball receiving valve; 22. First sewage valve; 23. Ball receiving cylinder; 24. Second sewage valve; 25. Ball receiving cylinder quick-opening blind plate; 26. Waste liquid tank inlet valve; 27. Waste liquid tank; 28. Upstream of pipeline to be cleaned; 29. ​​Downstream of pipeline to be cleaned. DETAILED DESCRIPTION

[0035] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0036] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0037] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0038] In the present invention, terms such as "upper", "lower", "left", "right", "front", "back", "vertical", "horizontal", "side", "bottom", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings. They are relational words determined only for the convenience of describing the structural relationships of the various parts or elements of the present invention, and do not specifically refer to any part or element in the present invention and should not be understood as limitations on the present invention.

[0039] In the present invention, terms such as "fixed connection", "connected", "connection", etc. should be understood in a broad sense, indicating that it can be fixedly connected, integrally connected or detachably connected; it can be directly connected or indirectly connected through an intermediate medium. For relevant scientific research or technical personnel in this field, the specific meanings of the above terms in the present invention can be determined according to specific circumstances, and they cannot be understood as limitations on the present invention.

[0040] In the absence of conflict, the embodiments of the present invention and the features of the embodiments may be combined with each other.

[0041] Embodiment 1

[0042] Embodiment 1 of the present invention introduces a method for preparing ice slurry.

[0043] like Figure 1 A method for preparing ice slurry is shown, comprising:

[0044] Obtain pipeline parameters of the oil and gas pipeline to be cleaned;

[0045] Calculate the melting rate of ice slurry in the oil and gas pipeline to be cleaned according to the obtained pipeline parameters;

[0046] Combined with the obtained melting rate of ice slurry, the shear stress of ice slurry at the end of the pipeline to be cleaned is calculated;

[0047] Based on the obtained shear stress, the ice slurry cleaning parameters are determined to complete the preparation of the ice slurry.

[0048] As one or more implementation methods, according to the pipeline design parameters and on-site operation conditions, the pipeline ambient temperature, diameter, length, wall thickness, pipe wall material, insulation material, pipe wall impurities and other parameters are obtained. The melting rate of the ice slurry cleaning process is calculated based on the collected pipeline and environmental parameters. First, the pipe wall temperature and the ice slurry injection temperature are determined, and the pipe wall temperature is set to the ambient temperature. The ice slurry injection temperature is generally -5°C. The changes in the pipe wall temperature and the ice slurry temperature during the entire cleaning process are calculated based on the pipeline related parameters, initial ice fraction, initial ice slurry volume and cleaning speed; secondly, the ice slurry melting rate is calculated based on the difference between the pipe wall temperature and the ice slurry temperature, and the melting rate under different ice fractions and cleaning speeds is obtained.

[0049] As one or more implementation modes, the change value of ice fraction during the pipe cleaning process is calculated by the melting rate obtained under different conditions during the ice slurry pipe cleaning process, and the change value of ice fraction along the pipeline is obtained; the shear stress of ice slurry is calculated according to parameters such as particle size, ice fraction, and pipe cleaning speed, and the change value of shear stress along the pipeline is obtained.

[0050] As one or more implementation modes, the shear stress value at the end of the pipeline is found according to the obtained ice slurry shear stress change value, and compared with the minimum shear stress required to remove impurities from the pipe wall. If the shear stress at the end of the ice slurry is greater than the minimum shear stress required to remove impurities from the pipe wall, the ice slurry particle size, ice fraction, ice slurry volume, pipe cleaning speed and other pipe cleaning parameters are selected to meet the requirements.

[0051] In order to ensure good fluidity of the ice slurry, in this embodiment, the types of freezing point inhibitors are usually salts, alcohols and surfactants, etc., and the mass percentage is usually 5% to 10% to ensure good fluidity of the ice slurry. Considering the shear stress and melting problems of the ice slurry, the particle size of the ice particles prepared in step S2 is usually less than 1mm, the ice fraction range is usually 50% to 60%, and the volume of the ice slurry is usually 20% to 40% of the volume of the oil and gas pipeline to be cleaned.

[0052] Embodiment 2

[0053] The second embodiment of the present invention introduces an oil and gas pipeline cleaning device based on ice slurry.

[0054] like Figure 2The oil and gas pipeline cleaning device based on ice slurry shown includes an ice slurry storage tank 1, an ice slurry storage tank outlet valve 2, a volumetric pump 3, a volumetric pump outlet pressure gauge 4, a volumetric pump outlet valve 5, a flow meter 6, a ball-launching cylinder quick-opening blind plate 7, a ball-launching cylinder 8, a ball-launching valve 9, a ball-launching cylinder oil inlet valve 10, a ball-launching cylinder bypass valve 11, a ball-launching cylinder pressure gauge 12, a ball-launching indicator 13, a first main valve 14, a second main valve 15, a pipeline to be cleaned 16, a ball-collecting cylinder oil outlet valve 17, a ball-passing indicator 18, a ball-collecting cylinder pressure gauge 19, a ball-collecting cylinder bypass valve 20, a ball-collecting valve 21, a first sewage valve 22, a ball-collecting cylinder 23, a second sewage valve 24, a ball-collecting cylinder quick-opening blind plate 25, a waste liquid tank inlet valve 26, a waste liquid tank 27, an upstream pipeline 28 to be cleaned, and a downstream pipeline 29 to be cleaned.

[0055] Next, this embodiment combines Figure 2 Expand the structure in detail.

[0056] The ice slurry prepared in Example 1 is stored in an ice slurry storage tank 1, and continuous insulation and stirring are required during the storage process; an ice slurry storage tank outlet valve 2 is provided on the outlet pipe of the ice slurry storage tank 1 for controlling the output of the ice slurry in the ice slurry storage tank 1, and a volumetric pump 3 for conveying ice slurry, a volumetric pump outlet pressure gauge 4 for measuring the outlet pressure value of the volumetric pump 3, a volumetric pump outlet valve 5 and a flow meter 6 for measuring the flow rate of ice slurry are sequentially provided on the side pipe of the ice slurry storage tank outlet valve 2 away from the ice slurry storage tank 1.

[0057] The flow meter 6 is connected to the ball serving cylinder 8 through a pipeline. It should be noted that a ball serving cylinder quick-opening blind plate 7 for controlling whether ice slurry can flow in is provided on the ball serving cylinder 8 near the side of the flow meter 6. A ball serving cylinder bypass valve 11, a ball serving cylinder pressure gauge 12 and a ball serving indicator valve 13 are provided on the ball serving cylinder 8 in sequence. The ball serving cylinder 8 near the ball serving indicator valve 13 is connected to the ball serving valve 9 through a pipeline, and the other side of the ball serving valve 9 is respectively connected to the first main valve 14 and the pipeline to be cleaned 16; one side of the first main valve 14 away from the ball serving valve 9 is connected to the upstream 28 of the pipeline to be cleaned and the ball serving cylinder oil inlet valve 10, and the other side of the ball serving cylinder oil inlet valve 10 is connected to the ball serving cylinder 8.

[0058] A ball receiving valve 21 and a second main valve 15 are provided on the other side of the pipeline to be cleaned 16, and a ball receiving cylinder 23 is provided at one end of the ball receiving valve 21 away from the pipeline to be cleaned 16, and a ball passing indicator 18, a ball receiving cylinder pressure gauge 19 and a ball receiving cylinder bypass valve 20 are provided on the ball receiving cylinder 23; the other side of the second main valve 15 is respectively connected to the downstream of the pipeline to be cleaned 29 and the ball receiving cylinder oil outlet valve 17, and the other side of the ball receiving cylinder oil outlet valve 17 is connected to the ball receiving cylinder 23; the ball receiving cylinder 23 is provided with a first sewage outlet 22 and a second sewage outlet 24, and the outlets of the first sewage outlet 22 and the second sewage outlet 24 are connected.

[0059] A ball collecting cylinder quick opening blind plate 25 for controlling whether ice slurry can flow out is arranged on the ball collecting cylinder 23 away from the ball collecting valve 21 , and a waste liquid tank inlet valve 26 and a waste liquid tank 27 are arranged on the pipeline on one side of the ball collecting cylinder quick opening blind plate 25 .

[0060] Embodiment 3

[0061] The third embodiment of the present invention introduces an oil and gas pipeline cleaning method based on ice slurry, which adopts the oil and gas pipeline cleaning device based on ice slurry introduced in the second embodiment.

[0062] like Figure 3 The oil and gas pipeline cleaning method based on ice slurry comprises:

[0063] Close the first main valve and the second main valve, open the ball valve and the ball valve, and inject ice slurry into the pipeline to be cleaned;

[0064] The injected ice slurry is measured by a flow meter, and when the preset flow rate of ice slurry is injected, the injection of the ice slurry is completed;

[0065] Open the oil inlet valve of the ball launching cylinder and the oil outlet valve of the ball collecting cylinder, adjust the opening of the oil inlet valve of the ball launching cylinder according to the melting rate of the ice slurry and the shear stress, and control the ice slurry pipe cleaning speed; when the ice slurry reaches the ball collecting cylinder, open the inlet valve of the waste liquid tank, close the oil outlet valve of the ball collecting cylinder, and the ice slurry after pipe cleaning enters the waste liquid tank.

[0066] It should be noted that before using the ice slurry-based oil and gas pipeline cleaning device, all valves are in a closed state.

[0067] This embodiment combines Figure 2 Expand the detailed introduction of injecting ice slurry into the pipe to be cleaned:

[0068] Open the ice slurry storage tank outlet valve 2, the volumetric pump 3, the volumetric pump outlet valve 5, the flow meter 6, the ball-launching barrel quick-opening blind plate 7, the ball-launching valve 9, the ball-launching barrel bypass valve 11, the ball-collecting barrel bypass valve 20 and the ball-collecting valve 21 in the ice slurry-based oil and gas pipeline cleaning device, and start to transport ice slurry into the pipeline under the action of the volumetric pump 3. The transported ice slurry enters the pipeline 16 to be cleaned after passing through the ball-launching barrel 8.

[0069] In this embodiment, the volume of the injected ice slurry is calculated based on the shear stress requirement of the ice slurry at the end. The injected ice slurry is measured by the flow meter 6. When the injected volume is reached, the injection of the ice slurry is completed.

[0070] After the injection of ice slurry is completed, it is necessary to close the ice slurry storage tank outlet valve 2, the volumetric pump 3, the volumetric pump outlet valve 5, the flow meter 6, and the ball-launching cylinder quick-opening blind plate 7, open the ball-launching cylinder oil inlet valve 10 and the ball-collecting cylinder oil outlet valve 17, so that the pipeline conveying medium in the upstream 28 of the pipeline to be cleaned enters the ball-launching cylinder through the ball-launching cylinder oil inlet valve, and then pushes the ice slurry to move into the pipeline to be cleaned 16, and starts to use the ice slurry to clean the pipeline.

[0071] like Figure 4 As shown, during the cleaning process, the opening of the ball receiving cylinder oil inlet valve 10 is adjusted according to the melting rate and shear stress of the prepared ice slurry, and the ice slurry pipe cleaning speed range is controlled to be 0.3-1.0 m / s, and the ice slurry pipe cleaning pressure is monitored in real time by the ball sending cylinder pressure gauge 12 and the ball receiving cylinder pressure gauge 19.

[0072] During the cleaning process, the change of ice slurry length along the pipe length is calculated according to the pipe material parameters, the temperature difference between the pipe wall and the ice slurry, the ice fraction and other parameters, and the ice slurry length at the end of the pipe is obtained. The time when the ice slurry reaches the ball collecting cylinder is obtained by the ratio of the difference between the pipe length and the ice slurry length at the end and the cleaning speed. The time when the ice slurry is completely discharged from the ball collecting cylinder is obtained according to the ratio of the pipe length to the cleaning speed. Set the same time interval, open the first drain valve 22 and the second drain valve 24 multiple times to collect ice slurry samples, collect and detect the residual amount of impurities such as sludge and wax in the ice slurry samples, and judge the effect of ice slurry cleaning.

[0073] When the ice slurry is completely removed, close the ball collecting cylinder oil outlet valve 17, open the ball collecting cylinder quick opening blind plate 25 and the waste liquid tank inlet valve 26, and the ice slurry after cleaning the pipeline enters the waste liquid tank 27 through the waste liquid tank inlet valve 26, and the ice slurry after cleaning is collected and stored.

[0074] It should be noted that during the entire ice slurry-based oil and gas pipeline cleaning process, the first main valve 14 and the second main valve 15 are always in a closed state.

[0075] Calculation example

[0076] This example uses an oil and gas mixed pipeline that has been in operation for about 20 years as an oil and gas pipeline to be cleaned.

[0077] The current status of the oil and gas pipeline to be cleaned is investigated: the ambient temperature is 10°C, the length is 2km, the pipeline specification is 12″×18″, the wall thickness is 12.7mm, the design pressure is 4.5MPa, the design temperature is 65°C, and the impurities on the pipe wall are crude oil and wax. Therefore, it is determined that the 2km long oil and gas pipeline to be cleaned in this embodiment meets the conditions for ice slurry cleaning. The ice slurry ice fraction, flow rate, and ice slurry volume are calculated according to the calculation formula.

[0078] According to the pipeline parameters and ice slurry injection parameters, the changes of pipe wall temperature and ice slurry temperature along the pipeline can be obtained, that is, the calculation formula of ice slurry temperature and pipe wall temperature:

[0079]

[0080] Where T is the ice slurry temperature, K; (ρC p ) is Ice slurry volume heat capacity, J / (m 3 ·K); Cp is is the specific heat capacity of ice slurry, J / (kg / m 3 ), u is the flow velocity, m / s, λ is is the thermal conductivity of ice slurry, W / (m·K); λ p is the thermal conductivity of the tube wall, W / (m·K); U I U value between ice slurry and pipe wall, W / (m2·K); T p is the tube wall temperature, K; r I is the inner radius of the pipe, m; r o is the outer radius of the pipe, m; (ρCp) P is the volume heat capacity of the tube wall, J / (m3·K); ρ P is the pipe density, kg / m3; Cp P is the specific heat capacity of the pipeline, J / (kg / m3); T e is the ambient temperature, K; U O is the U value between the fluid and the pipe wall, W / (m2·K); h is the convective heat transfer coefficient between the pipe and seawater.

[0081] The difference between the pipe wall temperature and the ice slurry temperature is brought in, and the melting rate of the ice slurry is calculated by combining the pipe diameter, length, and ice slurry physical properties. That is, the melting rate calculation temperature is:

[0082]

[0083] Where, λ is the thermal conductivity of ice slurry, W / (m·K); h if Latent heat of fusion, J / kg; V melt is the melting volume m 3 ; V is is the ice slurry volume, m 3 ; l is is the ice slurry length, m; ρ is is the ice slurry density, kg / m 3 ; u is the ice slurry cleaning speed, m / s.

[0084] The remaining ice particle volume is calculated by the melting rate of the ice slurry, and the change of ice fraction along the pipeline is calculated by the ratio of the remaining ice particle volume to the injected ice slurry volume, and the ice fraction calculation formula is obtained; that is,

[0085]

[0086] Among them, V iVolume of ice particles after melting, m 3 ; M is the melting rate.

[0087] The shear stress variation along the pipeline is calculated based on the parameters such as pipeline diameter, ice slurry particle size, ice fraction, and cleaning speed. The shear stress at the end of the pipeline is compared with the minimum shear stress required to remove impurities on the pipe wall. If the shear stress at the end of the pipeline is greater than the minimum shear stress required to remove impurities on the pipe wall, it means that the particle size, ice fraction, ice slurry volume, and cleaning speed meet the requirements. The shear stress calculation formula adopts the HB model, that is,

[0088]

[0089] Among them, τ w is the wall shear stress, Pa; γ w is the shear rate, s -1 ; τ y is the yield stress, Pa; d is the ice particle size, m; K is the rheological coefficient, Pa·s; p is the rheological index; γ crit is the critical shear rate, s -1 .

[0090] The initial length of the ice slurry is obtained according to the selected injected ice slurry volume and the pipe diameter; the change of the ice slurry length along the pipe is calculated according to the pipe parameters, the temperature difference between the pipe wall and the ice slurry, the ice slurry parameters, etc.; the change of the ice slurry volume is obtained by the change of the ice slurry length and the pipe diameter, and the calculation formula of the ice slurry length is obtained, namely

[0091]

[0092] e pipe =(r o -r I )ρ P C pP ΔT;

[0093]

[0094] Among them, l is0 is the initial length of ice slurry, m; e pipe Provides the maximum energy per unit area of ​​the actual pipeline, J / m 2 ; e is the maximum energy per unit area provided by a pipe with infinite wall thickness, J / m 2 ; V is is the ice slurry volume, m 3 .

[0095] According to the design parameters and production operation parameters of the oil and gas pipeline to be cleaned, the freezing point inhibitor required for preparing the ice slurry is determined to be 5wt.% sodium chloride, the ice slurry particle size is selected to be 0.3mm, the ice fraction is selected to be in the range of 52% to 60%, and the ice slurry volume range is 11.192m3 to 51.76m3. According to the site conditions, ice is made on the cleaning site or transported to the cleaning site through the ice slurry storage tank after preparation.

[0096] According to the location of oil and gas pipelines, ball launching barrels and ball receiving barrels, determine the installation location of ice slurry storage tanks and waste liquid tanks, open up temporary sites for the storage of vehicles and equipment, and set up site cordons.

[0097] Before the ice slurry is injected into the pipeline, the ice slurry storage tank 1 is connected to the volumetric pump 3 and the electromagnetic flowmeter 6, and the pumping pressure is measured at the outlet of the volumetric pump 3, wherein the ice slurry storage tank outlet valve 2 and the volumetric pump outlet valve 5 are installed at the outlet of the ice slurry storage tank 1 and on the ice slurry injection pipeline; the ball cylinder quick-opening blind plate 7 is opened, and the ice slurry injection pipeline is connected to the ball cylinder 8; the ball collection cylinder 23 is connected to the waste liquid tank 27 through the waste liquid tank inlet valve 26; the ball valve 9 and the ball collection valve 21 are opened, the first main valve 14 and the second main valve 15 are closed, and the ball cylinder 8 and the ball collection cylinder 23 are connected to the oil and gas pipeline to be cleaned. During the ice slurry injection process, the outlet pressure of the volumetric pump 3 and the ice slurry injection flow are detected by the volumetric pump outlet pressure gauge 4 and the flowmeter 6.

[0098] After the ice slurry injection is completed, disconnect the ball-launching cylinder 8 from the ice slurry injection pipeline, close the ball-launching cylinder quick-opening blind plate 7, open the ball-launching cylinder oil inlet valve 10, open the ball-receiving cylinder oil outlet valve 17, and use the original conveying medium in the oil and gas pipeline to promote the ice slurry to clean the pipe. According to the melting rate of the ice slurry and the shear stress requirements, adjust the opening of the ball-receiving cylinder oil inlet valve 10 to control the ice slurry cleaning speed range to 0.3-1.0 m / s, and monitor the ice slurry cleaning pressure through the ball-launching cylinder pressure gauge 12; the original medium in the pipe promotes the ice slurry to clean the pipe, and the time when the ice slurry arrives at the ball-receiving cylinder 23 is obtained according to the length of the oil and gas pipeline and the ice slurry cleaning speed; open the waste liquid tank inlet valve 26, close the ball-receiving cylinder oil outlet valve 17, and the ice slurry after cleaning passes through valve 26 and finally enters the waste liquid tank 27.

[0099] When the ice slurry starts to be discharged from the ball collecting cylinder 23, the time it takes for the ice slurry to be completely discharged is obtained based on the ice slurry length and the pipe cleaning speed. At the same time interval, the first sewage valve 22 and the second sewage valve 24 are opened to collect 10 ice slurry samples for testing, and the residual amount of impurities such as sludge and wax in the ice slurry is checked. The collected ice slurry is chemically tested to determine whether the pipe cleaning effect is up to standard.

[0100] This embodiment optimizes the ice slurry cleaning parameters and combines the original medium pressure in the oil and gas pipeline to make the ice slurry shear stress greater than the impurity adhesion force, thereby improving the cleaning effect. Due to the melting property of ice slurry, when a blockage occurs, the ice slurry can be discharged by melting, without causing damage to the pipeline and equipment, significantly reducing the risk of accidents.

[0101] The original ball receiving device and ball launching device of the oil and gas pipeline are used for improvement, and no additional large-scale equipment investment is required, which significantly reduces the cost of cleaning the pipeline. The ice slurry melts into water after the cleaning is completed, and will not cause pollution to the environment after being discharged from the pipeline. Compared with the traditional cleaning technology, the present invention is cleaner and more environmentally friendly.

[0102] The above description is only a preferred embodiment of the present embodiment and is not intended to limit the present embodiment. For those skilled in the art, the present embodiment may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present embodiment shall be included in the protection scope of the present embodiment.

Claims

1. A method for preparing ice slurry, characterized in that: include: Obtain pipeline parameters of the oil and gas pipeline to be cleaned; Calculate the melting rate of ice slurry in the oil and gas pipeline to be cleaned according to the obtained pipeline parameters; Combined with the obtained melting rate of ice slurry, the shear stress of ice slurry at the end of the pipeline to be cleaned is calculated; Based on the obtained shear stress, the ice slurry cleaning parameters are determined to complete the preparation of the ice slurry.

2. A method for preparing ice slurry as claimed in claim 1, characterized in that: The obtained pipeline parameters include at least pipeline ambient temperature, diameter, length, wall thickness, pipe wall material, insulation material and pipe wall impurities; the outer wall temperature of the pipeline is set to the ambient temperature, and the changes of the pipe wall temperature and the ice slurry temperature in the whole pipe cleaning process are calculated according to the pipeline related parameters, initial ice fraction, initial ice slurry volume and pipe cleaning speed; the ice slurry melting rate is calculated according to the difference between the pipeline ambient temperature and the ice slurry temperature, and the melting rate under different ice fractions and pipe cleaning speeds is obtained.

3. A method for preparing ice slurry as claimed in claim 2, characterized in that: The melting rate obtained under different conditions during the ice slurry cleaning process is used to calculate the change in ice fraction during the cleaning process, and the change in ice fraction along the pipeline is obtained. The shear stress of the ice slurry is calculated based on the particle size, ice fraction and cleaning speed, and the change in shear stress along the pipeline is obtained.

4. A method for preparing ice slurry as claimed in claim 3, characterized in that: According to the obtained change in ice slurry shear stress, the shear stress value at the end of the pipeline is calculated and compared with the minimum shear stress required to remove impurities from the pipe wall. If the shear stress at the end of the ice slurry is greater than the minimum shear stress required to remove impurities from the pipe wall, the ice slurry particle size, ice fraction, ice slurry volume and pipe cleaning speed at this time are used as ice slurry pipe cleaning parameters.

5. An oil and gas pipeline cleaning device based on ice slurry, characterized in that: It comprises an ice slurry assembly, a ball-serving assembly, a pipeline to be cleaned, a ball-receiving assembly and a waste liquid assembly which are sequentially connected; wherein the ice slurry assembly comprises an ice slurry storage tank for placing ice slurry prepared by the ice slurry preparation method as described in any one of claims 1 to 4 and a flowmeter for measuring the flow rate of ice slurry; the ball-serving assembly comprises a ball-serving barrel, a ball-serving valve, a ball-serving barrel oil inlet valve, a first main valve and an upstream of the pipeline to be cleaned, one end of the upstream of the pipeline to be cleaned is connected to the ball-serving barrel oil inlet valve and the first main valve, the ball-serving barrel and the ball-serving valve are connected in series, and the other ends of the ball-serving barrel oil inlet valve and the first main valve are connected to the ball-serving barrel and the ball-serving valve respectively; the ball-receiving assembly comprises an ice slurry storage tank for storing ice slurry prepared by the ice slurry preparation method as described in any one of claims 1 to 4 and a flowmeter for measuring the flow rate of ice slurry; the ball-serving assembly comprises a ball-serving barrel, a ball-serving valve, a ball-serving barrel oil inlet valve, a first main valve and an upstream of the pipeline to be cleaned, one end of the upstream of the pipeline to be cleaned is connected to the ball-serving barrel oil inlet valve and the first main valve, the ball-serving barrel and the ball-serving valve are connected in series, and the other ends of the ball-serving barrel oil inlet valve and the first main valve are connected to the ball-serving barrel and the ball-serving valve respectively; The component includes a ball collecting cylinder, a ball collecting valve, a ball collecting cylinder oil outlet valve, a second main valve and a downstream pipeline to be cleaned, one end of the downstream pipeline to be cleaned is connected to the ball collecting cylinder oil outlet valve and the second main valve, the ball collecting cylinder and the ball collecting valve are connected in series, and the other ends of the ball collecting cylinder oil outlet valve and the second main valve are connected to the ball collecting cylinder and the ball collecting valve respectively; one end of the pipeline to be cleaned is connected to the ball sending valve and the first main valve, and the other end is connected to the ball receiving valve and the second main valve; the waste liquid component includes a waste liquid tank inlet valve and a waste liquid tank, one end of the waste liquid tank inlet valve is connected to the ball collecting cylinder away from the pipeline to be cleaned, and the other end is connected to the waste liquid tank.

6. An oil and gas pipeline cleaning device based on ice slurry as claimed in claim 5, characterized in that: An ice slurry storage tank outlet valve, a volumetric pump, a volumetric pump outlet pressure gauge and a volumetric pump outlet valve are arranged in sequence between the ice slurry storage tank and the flow meter; a ball launching cylinder quick-opening blind plate is arranged at the end of the ball launching cylinder near the flow meter side; and a ball receiving cylinder quick-opening blind plate is arranged at the end of the ball receiving cylinder near the waste liquid tank inlet valve side.

7. An oil and gas pipeline cleaning device based on ice slurry as claimed in claim 5, characterized in that: The ball serving cylinder is provided with a ball serving cylinder bypass valve, a ball serving cylinder pressure gauge and a ball serving indicator in sequence; the ball receiving cylinder is provided with a ball receiving cylinder bypass valve, a ball receiving cylinder pressure gauge and a ball passing indicator in sequence; the ball receiving cylinder is provided with a first sewage valve and a second sewage valve, and the other end of the first sewage valve is connected to the other end of the second sewage valve.

8. An ice slurry-based oil and gas pipeline cleaning method, using the ice slurry-based oil and gas pipeline cleaning device according to any one of claims 5 to 7, characterized in that: include: Close the first main valve and the second main valve, open the ball valve and the ball valve, and inject ice slurry into the pipeline to be cleaned; The injected ice slurry is measured by a flow meter, and when the preset flow rate of ice slurry is injected, the injection of the ice slurry is completed; Open the oil inlet valve of the ball launching cylinder and the oil outlet valve of the ball collecting cylinder, adjust the opening of the oil inlet valve of the ball launching cylinder according to the melting rate of the ice slurry and the shear stress, and control the ice slurry pipe cleaning speed; when the ice slurry reaches the ball collecting cylinder, open the inlet valve of the waste liquid tank, close the oil outlet valve of the ball collecting cylinder, and the ice slurry after pipe cleaning enters the waste liquid tank.

9. The oil and gas pipeline cleaning method based on ice slurry as claimed in claim 8, characterized in that: It also includes pipe cleaning effect detection. Specifically, according to the time when the ice slurry reaches the ball collecting barrel and the time when the ice slurry is completely discharged, the same time interval is set, the first sewage valve and the second sewage valve are opened multiple times to collect ice slurry samples, and the residual amount in the ice slurry sample is collected and detected to judge the ice slurry pipe cleaning effect.

10. The oil and gas pipeline cleaning method based on ice slurry as claimed in claim 9, characterized in that: According to the pipeline material parameters, the temperature difference between the pipe wall and the ice slurry, and the ice fraction, the change of the ice slurry length along the pipe length is calculated to obtain the ice slurry length at the end of the pipeline. The time for the ice slurry to reach the ball collecting barrel is obtained by the ratio of the difference between the pipe length and the ice slurry length at the end to the pipe cleaning speed. The time for the ice slurry to be completely discharged from the ball collecting barrel is obtained according to the ratio of the pipeline length to the pipe cleaning speed.

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