Gathering and transportation methods, systems, and electronic equipment for produced fluids from oilfields with extremely high water content

Abstract

This disclosure provides a method, system, and electronic equipment for gathering and transporting produced fluids from oilfields with extremely high water content. The method includes: setting a target gathering and transport temperature for the produced fluid that is greater than its critical gathering and transport temperature and less than its critical wall adhesion temperature. The critical gathering and transport temperature is defined as the temperature at which the adhesion force of the water-bearing condensate deposits formed during the gathering and transport of the produced fluid along the pipeline equals the pressure difference exerted by the produced fluid on the condensate deposits. The solution provided by this disclosure can conveniently and accurately determine the critical gathering and transport temperature below the critical wall adhesion temperature for safe gathering and transport of crude oil with extremely high water content. This allows for further reduction of oilfield energy consumption while ensuring safe gathering and transport.

Description

Technical Field

[0001] This article relates to, but is not limited to, the field of oilfield gathering and transportation, and particularly to, but is not limited to, a method, system, and electronic equipment for gathering and transporting produced fluids from an oilfield with extremely high water content. Background Technology

[0002] During the gathering and transportation of produced fluids from oilfields, the gathering system typically employs heating or water mixing measures to prevent severe oil condensation and adhesion to the walls, which could clog the gathering pipelines. Heating the produced fluids significantly increases the energy consumption of the gathering system, thereby increasing production costs.

[0003] Related research and experiments show that the operation of oilfield produced fluids with different water contents varies within gathering and transportation pipelines, and the resulting oil condensation and adhesion phenomena also have different impacts on the gathering and transportation process. For oilfield produced fluids with extremely high water content, safe gathering and transportation can be carried out at relatively low temperatures. For example, for oilfield produced fluids with relatively high water content, the "critical adhesion temperature" can be used instead of the pour point of the produced fluid as a boundary condition for safe gathering and transportation. The critical adhesion temperature refers to the temperature at which the adhesion rate of the produced fluid increases sharply as the gathering temperature decreases. Further lowering the temperature will cause a large number of oil droplets to adhere to the pipe wall, resulting in a significant increase in wellhead back pressure. However, in related technologies, there is still a lack of in-depth research on the operation of extremely high water-content crude oil within pipelines at the critical adhesion temperature.

[0004] Therefore, how to further reduce oilfield energy consumption while ensuring safe gathering and transportation is an urgent technical problem to be solved. Summary of the Invention

[0005] The following is an overview of the subject matter described in detail herein. This overview is not intended to limit the scope of the claims.

[0006] To accurately and reasonably determine the oil gathering temperature boundary below the critical wall adhesion temperature of waxy crude oil under ultra-high water cut conditions, this disclosure innovatively proposes a method to calculate the critical gathering and transportation temperature boundary by achieving force balance between the pressure differential squeezing force of the oil gathering pipeline and the adhesion force of the condensing section on the pipe wall. This method quantifies the oil gathering temperature and provides the advantage of accuracy and convenience in calculating the critical gathering and transportation temperature boundary. It can further reduce the gathering and transportation temperature below the wall adhesion temperature, thereby achieving further energy conservation and consumption reduction in oil fields.

[0007] This will further reduce the oil gathering temperature below the wall adhesion temperature, thereby achieving energy conservation and consumption reduction in the oilfield.

[0008] This disclosure provides a method for gathering and transporting produced fluid from oilfields with extremely high water content, the method comprising:

[0009] The target gathering and transportation temperature of the oilfield produced fluid is set to be greater than the critical gathering and transportation temperature of the oilfield produced fluid and less than the critical wall adhesion temperature of the oilfield produced fluid.

[0010] The critical gathering and transportation temperature of the oilfield produced fluid is the gathering and transportation temperature at which the adhesion force of the wall-adhering water-containing solidified oil section formed by the accumulation of the oilfield produced fluid along the oil gathering pipeline is equal to the squeezing force of the oilfield produced fluid on the wall-adhering solidified oil section.

[0011] In some embodiments provided in this disclosure, the method for obtaining the critical gathering and transportation temperature T1 includes the following steps:

[0012] Get the following parameters:

[0013] The maximum allowable back pressure P0 of the produced fluid at the starting point of the gathering pipeline, the inner radius R of the gathering pipeline, the density ρ of the produced fluid, the dynamic viscosity μ of the produced fluid, the flow velocity v of the produced fluid in the gathering pipeline, the inlet pressure P1 of the produced fluid at the end of the gathering pipeline, the overall water cut φ of the produced fluid, and the emulsified water cut of the produced fluid. The length L of the oil gathering pipeline from the wellhead to the inlet, and the pour point T of the oilfield produced fluid. GP The temperature T at the pipe wall of the oil collecting pipeline w Temperature T0 of the medium surrounding the oil gathering pipeline, absolute equivalent roughness e, heat transfer coefficient K of the oil gathering pipeline, outer diameter D of the oil gathering pipeline, mass flow rate G of the oilfield produced fluid, specific heat capacity c of the oilfield produced fluid at the average temperature of the oil gathering pipeline, gathering and transportation time t, initial shear stress τ0 at the pipe wall of the oil gathering pipeline, and kinematic viscosity ω of the produced fluid.

[0014] The above parameters can be categorized as follows:

[0015] (1) Physical properties of oilfield produced fluids: density ρ of oilfield produced fluid, dynamic viscosity μ of oilfield produced fluid, flow velocity v of oilfield produced fluid in oil gathering pipeline, comprehensive water content φ of oilfield produced fluid, emulsified water content of oilfield produced fluid. Pour point T of oilfield produced fluid GP , c, the specific heat capacity of the produced fluid at the average temperature of the oil collection point, and ω, the kinematic viscosity of the produced fluid.

[0016] (2) Specifications of oil gathering pipeline: inner radius R of oil gathering pipeline, outer diameter D of oil gathering pipeline, absolute equivalent roughness e, length L of oil gathering pipeline from wellhead to inlet, and heat transfer coefficient K of oil gathering pipeline.

[0017] (3) Operating parameters: the maximum allowable back pressure P0 of the produced fluid at the starting point of the gathering pipeline, the inlet pressure P1 of the produced fluid at the end of the gathering pipeline, the mass flow rate G of the produced fluid, the gathering and transportation time t, the initial shear stress τ0 at the pipe wall of the gathering pipeline, and the temperature T at the pipe wall of the gathering pipeline. w The temperature T0 of the medium surrounding the oil collection pipeline.

[0018] The critical gathering and transportation temperature T1 is calculated according to formula (1):

[0019]

[0020] In formula (1), P0 is the maximum allowable back pressure of the oilfield produced fluid at the starting point of the gathering pipeline, in Pa; λ is the hydraulic friction coefficient, dimensionless; L1 is the distance from the wellhead starting point where the friction temperature drops to the wall adhesion temperature, in m; R is the inner radius of the gathering pipeline, in m; and ρ is the density of the oilfield produced fluid, in kg / m³. 3 v is the flow velocity of the produced fluid in the oil gathering pipeline, in m / s; P1 is the inlet pressure of the produced fluid at the end of the oil gathering pipeline, in Pa; δ is the wall thickness of the sticky solidification section, in m; φ is the overall water content of the produced fluid, %. Emulsion water content of produced fluid from the oilfield, in %;

[0021] In formula (1), f -1 (F1) is the inverse function of F1 = f(T1), and the original function F1 = f(T1) is shown in formula (2):

[0022]

[0023] In formula (2), R is the inner radius of the oil gathering pipeline, in meters; φ is the comprehensive water content of the produced fluid from the oilfield, in percent. L1 is the emulsified water content of the produced fluid, in %; L2 is the distance from the wellhead starting point to the point where the friction temperature drops to the wall-sticking temperature, in meters; L3 is the distance from the end of the pipeline to the point where the friction temperature drops to the wall-sticking temperature (L2 = L - L1), in meters; L is the length of the oil gathering pipeline from the wellhead to the inlet, in meters; T0 is the temperature of the medium surrounding the oil gathering pipeline, in degrees Celsius; ψ is the axial heat dissipation parameter of the oil gathering pipeline, in meters. -1 ; l is the distance from the starting point of the integral infinitesimal segment of the oil collecting pipeline dl to the pipeline; the oil temperature on the infinitesimal segment of the oil collecting pipeline dl is T; a and b are fitting parameters, determined experimentally.

[0024] Formula (2) F1 is a function of T1, and Formula (1) is the inverse function of Formula (2). When using Formula (1), F1 in Formula (1) is calculated using Formula (1.1).

[0025]

[0026] In formula (1.1), P0 is the maximum allowable back pressure of the oilfield produced fluid at the starting point of the gathering pipeline, in Pa; λ is the hydraulic friction coefficient, dimensionless; L1 is the distance from the wellhead starting point where the friction temperature drops to the wall adhesion temperature, in meters; R is the inner radius of the gathering pipeline, in meters; and ρ is the density of the oilfield produced fluid, in kg / m³. 3 v is the flow velocity of the produced fluid in the oil gathering pipeline, in m / s; P1 is the inlet pressure of the produced fluid at the end of the oil gathering pipeline, in Pa; δ is the wall thickness of the sticky solidification section, in m; φ is the overall water content of the produced fluid, %. Emulsified water content of oilfield produced fluid, %.

[0027] In formula (1), the distance L1 from the wellhead starting point to the location where the friction temperature drops to the wall adhesion temperature is calculated according to formula (3):

[0028]

[0029] In formula (3), L is the length of the oil gathering pipeline from the wellhead to the inlet, in meters; ψ is the axial heat dissipation parameter of the oil gathering pipeline, in meters. -1 ;T GP φ is the pour point of the produced fluid in the oilfield, in °C; φ is the overall water content of the produced fluid in the oilfield, in %; τ is the shear stress at the inner wall of the oil gathering pipeline, in Pa; T0 is the temperature of the medium surrounding the oil gathering pipeline, in °C.

[0030] k, m, and n are fitting parameters, which are determined based on experiments;

[0031] The axial heat dissipation parameter ψ of the oil gathering pipeline in formula (3) is calculated according to formula (4):

[0032]

[0033] In formula (4), K is the heat transfer coefficient of the oil gathering pipeline, with units of W / (m). 2 ·℃); D is the outer diameter of the oil gathering pipeline, in m; G is the mass flow rate of the produced fluid from the oilfield, in kg / s; c is the specific heat capacity of the produced fluid from the oilfield at the average temperature of the oil gathering, in J / (kg·℃);

[0034] The shear stress τ at the inner wall of the oil gathering pipeline in formula (3) is calculated according to formula (5):

[0035]

[0036] In formula (5), μ is the dynamic viscosity of the oilfield produced fluid, in Pa·s; R is the inner radius of the oil gathering pipeline, in m; v is the flow velocity of the oilfield produced fluid in the oil gathering pipeline, in m / s;

[0037] In formula (1), the wall adhesion thickness δ of the wall-adhering solidification section is calculated according to formula (6):

[0038]

[0039] In formula (6), t is the collection and transportation time, in d; Δ is the wall adhesion velocity, in mm / d;

[0040] In formula (6), the wall-adhesion velocity Δ is calculated according to formula (7):

[0041]

[0042] In formula (7), τ0 is the initial shear stress at the pipe wall of the oil gathering pipeline, in Pa; φ is the comprehensive water cut of the produced fluid in the oilfield, %; τ is the shear stress at the inner wall of the oil gathering pipeline, in Pa; T GP T is the pour point of the produced fluid from the oilfield, expressed in °C. w The temperature at the pipe wall of the oil gathering pipeline is expressed in °C; d, e, f, g, h, i, and j are fitting parameters determined experimentally.

[0043] In formula (1), the hydraulic friction coefficient λ is calculated according to formulas (8), (9), (10), and (11):

[0044] Laminar flow region:

[0045] Hydraulically smooth zone:

[0046] Mixed friction zone:

[0047] Rough area:

[0048] In formulas (8), (9), (10), and (11), Re is the Reynolds number, ε is the relative equivalent roughness of the pipe wall (dimensionless), and e represents the absolute equivalent roughness (in meters). Formula (8) is applicable when Re < 2000, and formula (9) is applicable when... The applicable conditions for formula (10) are as follows: The applicable conditions for formula (11) are as follows:

[0049] In formulas (8), (9), (10), and (11), the Reynolds number Re is calculated according to formula (12), and the relative equivalent roughness ε of the pipe wall is calculated according to formula (13):

[0050]

[0051]

[0052] In formula (12), ω represents the kinematic viscosity of the produced fluid, m 2 / s; v is the flow velocity of the produced fluid in the oilfield in the oil gathering pipeline; R is the inner radius of the oil gathering pipeline, in meters.

[0053] In formula (13), e is the absolute equivalent roughness in m; R is the inner radius of the oil gathering pipeline in m.

[0054] In some embodiments provided in this disclosure, the fitting method for the fitting parameters k, m, and n in formula (3) is as follows: For multiphase produced fluids from oilfields with different comprehensive water cuts, the wall adhesion temperature T is tested by conducting a wall adhesion annular test. s The freezing point T was tested using a freezing point apparatus. GP The values ​​of k, m, and n are determined by fitting.

[0055] In some embodiments provided in this disclosure, the value of k ranges from 5.31 °C·Pa. -n Up to 17.94℃·Pa -n The value of m ranges from 1.71 to 5.43; the value of n ranges from 0.19 to 0.67.

[0056] In some embodiments provided in this disclosure, the value of k increases with the increase of the oil phase wax content in the multiphase produced fluid of the oilfield, while the values ​​of m and n decrease with the increase of the oil phase wax content in the multiphase produced fluid of the oilfield.

[0057] In some implementation schemes provided in this disclosure, the fitting method for the fitting parameters d, e, f, g, h, i, j in formula (5) is as follows: for multiphase produced fluids from oilfields with different comprehensive water cuts, a wall adhesion rate Δ is tested by conducting a wall adhesion loop experiment, and the values ​​of d, e, f, g, h, i, j are determined by fitting.

[0058] In some embodiments provided in this disclosure, the value of d ranges from 0.001 m·s. -1 ·Pa -e ·℃ -j up to 0.03 m·s -1 ·Pa -e ·℃ -jThe values ​​of e range from -1.91 to -0.53; the values ​​of f range from 0.37 to 0.99; the values ​​of g range from 4.27 to 8.63; the values ​​of h range from -0.99 to -0.03; the values ​​of i range from -2.14 to -0.99; and the values ​​of j range from 1.75 to 4.99.

[0059] The values ​​of d, e, h, and i increase with the increase of wax content in the oil phase of multiphase produced fluids from oilfields;

[0060] The values ​​of f, g, and j decrease as the wax content of the oil phase in the multiphase produced fluid of the oilfield increases.

[0061] In some embodiments provided in this disclosure, the method for obtaining the critical wall-sticking temperature includes the following steps:

[0062] Obtain the following parameters: Pour point T of the oilfield produced fluid. GP The overall water cut φ of the produced fluid from the oilfield, and the shear stress τ at the inner wall of the oil gathering pipeline.

[0063] The critical wall adhesion temperature T s Calculate according to formula (14):

[0064] T s =T GP -kφ m τ m …………………………(14)

[0065] In formula (14), T GP φ is the pour point of the produced fluid in the oilfield, in °C; φ is the overall water content of the produced fluid in the oilfield; τ is the shear stress at the inner wall of the oil gathering pipeline, in Pa.

[0066] k, m, and n are fitting parameters, which are the same as the fitting parameters k, m, and n in formula (3).

[0067] In some embodiments provided in this disclosure, the emulsified water content of the oilfield produced fluid The range is 0% to 47%.

[0068] In some embodiments provided in this disclosure, the water content of the oilfield produced fluid is 70% to 99%.

[0069] In some embodiments provided in this disclosure, the fitting methods for the fitting parameters k, m, n in formula (3) and formula (14) and the fitting parameters d, e, f, g, h, i, j in formula (7) include:

[0070] For multiphase produced fluids from oilfields with different overall water cuts, wall adhesion tests were conducted to measure the wall adhesion temperature T. sGiven the wall adhesion velocity Δ, and the annular channel material being the same as the pipeline material in the gathering and transportation method, the values ​​of k, m, n and the values ​​of d, e, f, g, h, i, j are determined by fitting.

[0071] Set up different comprehensive moisture contents (φ1, φ2, φ3... φ) n The oil-water mixture was tested using a pour point apparatus to measure the pour point (T) of the mixture with different water contents. GP1 ,T GP2 ,T GP3 ...T GPn The density of the mixture (ρ1, ρ2, ρ3...ρ) was measured using a hydrometer. n );

[0072] A loop test was conducted on the prepared crude oil emulsion, allowing the oil-water mixture to circulate within the pipeline while the system was slowly cooled. The test section had a pipe length of κ. When the test data showed a continuous increase in the pressure differential within the test section, the system temperature at this point was identified as the wall adhesion temperature (T) for mixtures with different water contents. s1 ,T s2 ,T s3 ...T sn According to formula (5), the shear stresses at the pipe wall are calculated as (τ1, τ2, τ3...τ). n The initial shear stress at the pipe wall is τ0, and the temperature at the pipe wall is T. w ;

[0073] After running for a period of time, record the pipeline pressure difference (ΔP1, ΔP2, ΔP3...ΔP) for oil-water mixtures with different water contents. n After running for a period of time Δt, record the pressure differences at this time as (ΔP′1, ΔP′2, ΔP′3...ΔP′). n );

[0074] Calculate the wall adhesion rate corresponding to different water contents of the mixture according to formula (15):

[0075]

[0076] In formula (15), v is the flow velocity of the oilfield produced fluid in the oil gathering pipeline (which is the flow velocity of the mixture in the loop test in formula (15)), in m / s; κ is the length of the test section pipe, in m; and a hydrometer is used to measure the density of the mixture (ρ1, ρ2, ρ3...ρ). n (Unit: kg / m³) 3 λ is the hydraulic friction coefficient, dimensionless; Δt is the experimental running time, in seconds; (ΔP1, ΔP2, ΔP3...ΔP n The unit of (ΔP′1, ΔP′2, ΔP′3...ΔP′) is Pa. nThe unit of ) is Pa;

[0077] The calculated wall adhesion rates of oil-water mixtures with different water contents are (Δ1, Δ2, Δ3...Δ n );

[0078] According to the experimental data set (T) s1 ,T s2 ,T s3 ...T sn ), (T GP1 ,T GP2 ,T GP3 ...T GPn (φ1,φ2,φ3...φ) n (τ1,τ2,τ3...τ) n The least squares method was used to fit the formula for calculating the wall adhesion temperature (14): T s =T GP -kφ m τ n Determine the values ​​of the fitting parameters k, m, and n;

[0079] Based on the experimental data set (Δ1, Δ2, Δ3...Δ n (φ1,φ2,φ3...φ) n (τ1,τ2,τ3...τ) n ), (T GP1 ,T GP2 ,T GP3 ...T GPn ), and τ0, T w The least squares method was used to fit the formula for calculating the wall adhesion rate (7), and the values ​​of the fitting parameters d, e, f, g, h, i, and j were determined.

[0080] In some embodiments provided in this disclosure, the fitting parameters a and b in formula (2) are fitted using the following experiments:

[0081] The yield stress of waxy crude oil increases exponentially with decreasing measurement temperature, conforming to formula (16):

[0082] τ y =exp(a-bT)……………………(16)

[0083] In the formula, τ y denoted as ρ, Pa; T is the yield stress of water-containing solidified oil adhering to the wall; and a and b are experimental fitting parameters.

[0084] By adjusting the temperature, the yield stress of the oilfield produced fluid was experimentally tested, and the fitting parameters a and b in formula (2) were obtained.

[0085] In some embodiments provided in this disclosure, the value of a ranges from 5.72 to 43.69; the value of b ranges from 0.01 to 0.97.

[0086] In some embodiments provided in this disclosure, the value of a increases with the increase of the oil phase wax content in the multiphase produced fluid of the oilfield, and the value of b decreases with the increase of the oil phase wax content in the multiphase produced fluid of the oilfield.

[0087] On another front, this disclosure provides a gathering and transportation system for oilfield produced fluids, including the aforementioned method for gathering and transporting oilfield produced fluids with extremely high water content, the system comprising:

[0088] The first acquisition module is used to acquire the following parameters: the maximum allowable back pressure P0 of the produced fluid at the starting point of the gathering pipeline, the inner radius R of the gathering pipeline, the density ρ of the produced fluid, the dynamic viscosity μ of the produced fluid, the flow velocity v of the produced fluid in the gathering pipeline, the inlet pressure P1 of the produced fluid at the end of the gathering pipeline, the comprehensive water content φ of the produced fluid, and the emulsified water content of the produced fluid. The length L of the oil gathering pipeline from the wellhead to the inlet, and the pour point T of the oilfield produced fluid. GP The temperature T at the pipe wall of the oil collecting pipeline w Temperature T0 of the medium surrounding the oil gathering pipeline, absolute equivalent roughness e, heat transfer coefficient K of the oil gathering pipeline, outer diameter D of the oil gathering pipeline, mass flow rate G of the produced fluid from the oilfield, specific heat capacity c of the produced fluid at the average temperature of the oil gathering pipeline, gathering and transportation time t, initial shear stress τ0 at the pipe wall of the oil gathering pipeline, and kinematic viscosity ω of the produced fluid.

[0089] The second acquisition module is used to calculate the critical gathering and transportation temperature of the oilfield produced fluid using formulas (1) to (13) and formulas (15) to (16); and to calculate the critical wall adhesion temperature of the oilfield produced fluid using formulas (14) and (15).

[0090] The third acquisition module is used to determine the target gathering and transportation temperature of the oilfield produced fluid based on the critical gathering and transportation temperature of the oilfield produced fluid; the target gathering and transportation temperature of the oilfield produced fluid is greater than the critical gathering and transportation temperature of the oilfield produced fluid and less than the critical wall adhesion temperature of the oilfield produced fluid.

[0091] The gathering and transportation module is used to gather and transport the produced fluid from the oilfield at the target gathering and transportation temperature.

[0092] In another aspect, this disclosure provides an electronic device including a memory and a processor, the memory storing a computer program, and the processor executing the method as described above when running the computer program.

[0093] In another aspect, this disclosure provides a storage medium for storing a computer-readable program, which, when run, performs the methods described above.

[0094] Compared with the prior art, the technical solutions provided in this disclosure have at least the following advantages:

[0095] This disclosure calculates the critical gathering and transportation temperature of produced fluid from ultra-high water-cut oilfields using a calculation function formula for critical gathering and transportation temperature. Based on this critical gathering and transportation temperature, a target gathering and transportation temperature is determined. The target gathering and transportation temperature is greater than the critical gathering and transportation temperature but less than the critical wall adhesion temperature. The produced fluid is then gathered and transported at the target temperature. This method allows for the convenient and accurate determination of the critical gathering and transportation temperature below the critical wall adhesion temperature, enabling safe gathering and transportation of ultra-high water-cut crude oil. This further reduces oilfield energy consumption while ensuring safe gathering and transportation.

[0096] Other features and advantages of this disclosure will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the disclosure. Other advantages of this disclosure may be realized and obtained by means of the methods described in the specification. Attached Figure Description

[0097] The accompanying drawings are used to provide an understanding of the technical solutions of this disclosure and form part of the specification. They are used together with the embodiments of this disclosure to explain the technical solutions of this disclosure and do not constitute a limitation on the technical solutions of this disclosure.

[0098] Figure 1 This is an exemplary schematic diagram illustrating the distribution characteristics of oil condensation along the walls of an oil gathering pipeline, according to some embodiments of this disclosure.

[0099] Figure 2 This is an exemplary schematic diagram showing the wall thickness and adhesion cross-sectional arc length of the wall-adhesive solidification section according to some embodiments of this disclosure.

[0100] Figure 3 This is an exemplary schematic diagram of a gathering and transportation system for oilfield produced fluids with extremely high water content, according to some embodiments of this disclosure.

[0101] Figure 4 This is an exemplary structural diagram of an electronic device according to some embodiments of the present disclosure.

[0102] Figure 5 This diagram illustrates the effect of gathering and transportation at 22°C and 20°C below the critical wall adhesion temperature, based on the critical gathering and transportation temperature obtained in Example 1, on the change of back pressure at the wellhead. Detailed Implementation

[0103] To more clearly illustrate the technical solutions of the embodiments of this disclosure, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are merely some examples or embodiments of this disclosure. For those skilled in the art, these drawings can be applied to other similar scenarios without creative effort. Unless obvious from the context or otherwise specified, the same reference numerals in the drawings represent the same structures or operations.

[0104] It should be understood that the terms “system,” “device,” “unit,” and / or “module” used herein are one method of distinguishing different components, elements, parts, sections, or assemblies at different levels. However, if other words can achieve the same purpose, they may be replaced by other expressions.

[0105] As shown in this disclosure and claims, unless the context clearly indicates otherwise, the words "a," "an," "an," and / or "the" are not specifically singular and may include the plural. Generally speaking, the terms "comprising" and "including" only indicate the inclusion of expressly identified steps and elements, which do not constitute an exclusive list, and the method or apparatus may also include other steps or elements.

[0106] Flowcharts are used in this disclosure to illustrate the operations performed by a system according to embodiments of this disclosure. It should be understood that the preceding or following operations are not necessarily performed in exact order. Instead, the steps can be processed in reverse order or simultaneously. Furthermore, other operations can be added to these processes, or one or more steps can be removed from them.

[0107] This disclosure provides an exemplary embodiment of a method for gathering and transporting produced fluid from an oilfield with extremely high water content, the method comprising:

[0108] The target gathering and transportation temperature of the oilfield produced fluid is set to be greater than the critical gathering and transportation temperature of the oilfield produced fluid and less than the critical wall adhesion temperature of the oilfield produced fluid.

[0109] The critical gathering and transportation temperature of the oilfield produced fluid is the gathering and transportation temperature at which the adhesion force of the wall-adhering water-containing solidified oil section formed by the accumulation of the oilfield produced fluid along the oil gathering pipeline is equal to the squeezing force of the oilfield produced fluid on the wall-adhering solidified oil section.

[0110] For example, the method for obtaining the critical gathering and transportation temperature T1 includes the following steps:

[0111] Get the following parameters:

[0112] The maximum allowable back pressure P0 of the produced fluid at the starting point of the gathering pipeline, the inner radius R of the gathering pipeline, the density ρ of the produced fluid, the dynamic viscosity μ of the produced fluid, the flow velocity v of the produced fluid in the gathering pipeline, the inlet pressure P1 of the produced fluid at the end of the gathering pipeline, the overall water cut φ of the produced fluid, and the emulsified water cut of the produced fluid. The length L of the oil gathering pipeline from the wellhead to the inlet, and the pour point T of the oilfield produced fluid. GP The temperature T at the pipe wall of the oil collecting pipeline w Temperature T0 of the medium surrounding the oil gathering pipeline, absolute equivalent roughness e, heat transfer coefficient K of the oil gathering pipeline, outer diameter D of the oil gathering pipeline, mass flow rate G of the oilfield produced fluid, specific heat capacity c of the oilfield produced fluid at the average temperature of the oil gathering pipeline, gathering and transportation time t, initial shear stress τ0 at the pipe wall of the oil gathering pipeline, and kinematic viscosity ω of the oilfield produced fluid.

[0113] The above parameters can be categorized as follows:

[0114] (1) Physical properties of oilfield produced fluids: density ρ of oilfield produced fluid, dynamic viscosity μ of oilfield produced fluid, flow velocity v of oilfield produced fluid in oil gathering pipeline, comprehensive water content φ of oilfield produced fluid, emulsified water content of oilfield produced fluid. Pour point T of oilfield produced fluid GP , c, the specific heat capacity of the produced fluid at the average temperature of the oil collection point, and ω, the kinematic viscosity of the produced fluid.

[0115] (2) Specifications of oil gathering pipeline: inner radius R of oil gathering pipeline, outer diameter D of oil gathering pipeline, absolute equivalent roughness e, length L of oil gathering pipeline from wellhead to inlet, and heat transfer coefficient K of oil gathering pipeline.

[0116] (3) Operating parameters: the maximum allowable back pressure P0 of the produced fluid at the starting point of the gathering pipeline, the inlet pressure P1 of the produced fluid at the end of the gathering pipeline, the mass flow rate G of the produced fluid, the gathering and transportation time t, the initial shear stress τ0 at the pipe wall of the gathering pipeline, and the temperature T at the pipe wall of the gathering pipeline. w The temperature T0 of the medium surrounding the oil collection pipeline.

[0117] The critical gathering and transportation temperature T1 is calculated according to formula (1):

[0118]

[0119] In formula (1), P0 is the maximum allowable back pressure of the oilfield produced fluid at the starting point of the gathering pipeline, in Pa; λ is the hydraulic friction coefficient, dimensionless; L1 is the distance from the wellhead starting point where the friction temperature drops to the wall adhesion temperature, in m; R is the inner radius of the gathering pipeline, in m; and ρ is the density of the oilfield produced fluid, in kg / m³. 3v is the flow velocity of the produced fluid in the oil gathering pipeline, in m / s; P1 is the inlet pressure of the produced fluid at the end of the oil gathering pipeline, in Pa; δ is the wall thickness of the sticky solidification section, in m; φ is the overall water content of the produced fluid, %. Emulsion water content of produced fluid from the oilfield, in %;

[0120] In formula (1), f -1 (F1) is the inverse function of F1 = f(T1), and the original function F1 = f(T1) is shown in formula (2):

[0121]

[0122] In formula (2), R is the inner radius of the oil gathering pipeline, in meters; φ is the comprehensive water content of the produced fluid from the oilfield, in percent. L1 is the emulsified water content of the produced fluid, in %; L2 is the distance from the wellhead starting point to the point where the friction temperature drops to the wall-sticking temperature, in meters; L3 is the distance from the end of the pipeline to the point where the friction temperature drops to the wall-sticking temperature (L2 = L - L1), in meters; L is the length of the oil gathering pipeline from the wellhead to the inlet, in meters; T0 is the temperature of the medium surrounding the oil gathering pipeline, in degrees Celsius; ψ is the axial heat dissipation parameter of the oil gathering pipeline, in meters. -1 ; l is the distance from the starting point of the integral infinitesimal segment of the oil collecting pipeline dl to the pipeline; the oil temperature on the infinitesimal segment of the oil collecting pipeline dl is T; a and b are fitting parameters, determined experimentally.

[0123] Formula (2) F1 is a function of T1, and Formula (1) is the inverse function of Formula (2). When using Formula (1), F1 in Formula (1) is calculated using Formula (1.1).

[0124]

[0125] In formula (1.1), P0 is the maximum allowable back pressure of the oilfield produced fluid at the starting point of the gathering pipeline, in Pa; λ is the hydraulic friction coefficient, dimensionless; L1 is the distance from the wellhead starting point where the friction temperature drops to the wall adhesion temperature, in meters; R is the inner radius of the gathering pipeline, in meters; and ρ is the density of the oilfield produced fluid, in kg / m³. 3 v is the flow velocity of the produced fluid in the oil gathering pipeline, in m / s; P1 is the inlet pressure of the produced fluid at the end of the oil gathering pipeline, in Pa; δ is the wall thickness of the sticky solidification section, in m; φ is the overall water content of the produced fluid, %. Emulsified water content of oilfield produced fluid, %.

[0126] In formula (1), the distance L1 from the wellhead starting point to the location where the friction temperature drops to the wall adhesion temperature is calculated according to formula (3):

[0127]

[0128] In formula (3), L is the length of the oil gathering pipeline from the wellhead to the inlet, in meters; ψ is the axial heat dissipation parameter of the oil gathering pipeline, in meters. -1 ;T GP φ is the pour point of the produced fluid in the oilfield, in °C; φ is the overall water content of the produced fluid in the oilfield, in %; τ is the shear stress at the inner wall of the oil gathering pipeline, in Pa; T0 is the temperature of the medium surrounding the oil gathering pipeline, in °C.

[0129] k, m, and n are fitting parameters, which are determined based on experiments;

[0130] The axial heat dissipation parameter ψ of the oil gathering pipeline in formula (3) is calculated according to formula (4):

[0131]

[0132] In formula (4), K is the heat transfer coefficient of the oil gathering pipeline, with units of W / (m). 2 ·℃); D is the outer diameter of the oil gathering pipeline, in m; G is the mass flow rate of the produced fluid from the oilfield, in kg / s; c is the specific heat capacity of the produced fluid from the oilfield at the average temperature of the oil gathering, in J / (kg·℃);

[0133] The shear stress τ at the inner wall of the oil gathering pipeline in formula (3) is calculated according to formula (5):

[0134]

[0135] In formula (5), μ is the dynamic viscosity of the oilfield produced fluid, in Pa·s; R is the inner radius of the oil gathering pipeline, in m; v is the flow velocity of the oilfield produced fluid in the oil gathering pipeline, in m / s;

[0136] In formula (1), the wall adhesion thickness δ of the wall-adhering solidification section is calculated according to formula (6):

[0137]

[0138] In formula (6), t is the collection and transportation time, in d; Δ is the wall adhesion velocity, in mm / d;

[0139] In formula (6), the wall-adhesion velocity Δ is calculated according to formula (7):

[0140]

[0141] In formula (7), τ0 is the initial shear stress at the pipe wall of the oil gathering pipeline, in Pa; φ is the comprehensive water cut of the produced fluid in the oilfield, %; τ is the shear stress at the inner wall of the oil gathering pipeline, in Pa; T GP T is the pour point of the produced fluid from the oilfield, expressed in °C. w The temperature at the pipe wall of the oil gathering pipeline is expressed in °C; d, e, f, g, h, i, and j are fitting parameters determined experimentally.

[0142] In formula (1), the hydraulic friction coefficient λ is calculated according to formulas (8), (9), (10), and (11):

[0143] Laminar flow region:

[0144] Hydraulically smooth zone:

[0145] Mixed friction zone:

[0146] Rough area:

[0147] In formulas (8), (9), (10), and (11), Re is the Reynolds number, ε is the relative equivalent roughness of the pipe wall (dimensionless), and e represents the absolute equivalent roughness (in meters). Formula (8) is applicable when Re < 2000, and formula (9) is applicable when... The applicable conditions for formula (10) are as follows: The applicable conditions for formula (11) are as follows:

[0148] In formulas (8), (9), (10), and (11), the Reynolds number Re is calculated according to formula (12), and the relative equivalent roughness ε of the pipe wall is calculated according to formula (13):

[0149]

[0150]

[0151] In formula (12), ω represents the kinematic viscosity of the produced fluid, m 2 / s; v is the flow velocity of the produced fluid in the oil gathering pipeline, in m / s; R is the inner radius of the oil gathering pipeline, in m.

[0152] In formula (13), e is the absolute equivalent roughness in m; R is the inner radius of the oil gathering pipeline in m.

[0153] For example, the fitting parameters a and b in formula (2) are fitted using the following experiment:

[0154] The yield stress of waxy crude oil increases exponentially with decreasing measurement temperature, conforming to formula (16):

[0155] τ y =exp(a-bT)……………………(16)

[0156] In the formula, τ y denoted as ρ, Pa; T is the yield stress of water-containing solidified oil adhering to the wall; and a and b are experimental fitting parameters.

[0157] By adjusting the temperature, the yield stress of the oilfield produced fluid was experimentally tested, and the fitting parameters a and b in formula (2) were obtained.

[0158] For example, the value of a ranges from 5.72 to 43.69; the value of b ranges from 0.01 to 0.97.

[0159] For example, the value of a increases with the increase of the oil phase wax content in the multiphase produced fluid of the oilfield, while the value of b decreases with the increase of the oil phase wax content in the multiphase produced fluid of the oilfield.

[0160] For example, the fitting method for the fitting parameters k, m, and n in formula (3) is as follows: For multiphase produced fluids from oilfields with different comprehensive water cuts, the wall adhesion temperature T is tested by conducting a wall adhesion annular test. s The freezing point T was tested using a freezing point apparatus. GP The values ​​of k, m, and n are determined by fitting.

[0161] For example, the value of k ranges from 5.31℃·Pa. -n Up to 17.94℃·Pa -n The value of m ranges from 1.71 to 5.43; the value of n ranges from 0.19 to 0.67.

[0162] For example, the value of k increases with the increase of the oil phase wax content in the multiphase produced fluid of the oilfield, while the values ​​of m and n decrease with the increase of the oil phase wax content in the multiphase produced fluid of the oilfield.

[0163] For example, the fitting method for the fitting parameters d, e, f, g, h, i, j in formula (5) is as follows: for multiphase produced fluids of oilfields with different comprehensive water cuts, conduct a wall adhesion test of the wall adhesion rate Δ, and fit and determine the values ​​of d, e, f, g, h, i, j.

[0164] For example, the value of d ranges from 0.001 m·s. -1 ·Pa -e ·℃ -j up to 0.03 m·s -1 ·Pa -e ·℃ -jThe values ​​of e range from -1.91 to -0.53; the values ​​of f range from 0.37 to 0.99; the values ​​of g range from 4.27 to 8.63; the values ​​of h range from -0.99 to -0.03; the values ​​of i range from -2.14 to -0.99; and the values ​​of j range from 1.75 to 4.99.

[0165] The values ​​of d, e, h, and i increase with the increase of wax content in the oil phase of multiphase produced fluids from oilfields;

[0166] The values ​​of f, g, and j decrease as the wax content of the oil phase in the multiphase produced fluid of the oilfield increases.

[0167] For example, the method for obtaining the critical wall-sticking temperature includes the following steps:

[0168] Obtain the following parameters: Pour point T of the oilfield produced fluid. GP The overall water cut φ of the produced fluid from the oilfield, and the shear stress τ at the inner wall of the oil gathering pipeline.

[0169] The critical wall adhesion temperature T s Calculate according to formula (14):

[0170] T s =T GP -kφ m τ n …………………………(14)

[0171] In formula (14), T GP φ is the pour point of the produced fluid in the oilfield, in °C; φ is the overall water content of the produced fluid in the oilfield; τ is the shear stress at the inner wall of the oil gathering pipeline, in Pa.

[0172] k, m, and n are fitting parameters, which are the same as the fitting parameters k, m, and n in formula (3).

[0173] For example, the emulsified water content of oilfield produced fluids The range is 0% to 47%.

[0174] For example, the water content of the oilfield produced fluid is 70% to 99%.

[0175] As an example only, Example 1: The oil well gathering pipeline is made of carbon steel, with a length L = 1300m from the wellhead to the inlet, an inner radius R = 26mm, a maximum allowable wellhead back pressure P0 = 3.2MPa for the produced fluid at the pipeline starting point, an inlet pressure P1 = 0.4MPa for the produced fluid at the pipeline end, a comprehensive water cut φ = 85.1%, and an emulsified water cut of the produced fluid. The density of the produced fluid in the oilfield is ρ = 869 kg / m³ 3The dynamic viscosity of the produced fluid from the oilfield is μ = 0.19 Pa·s, and the pour point of the produced fluid is T. GP =32℃, the flow velocity of the produced fluid in the oilfield in the oil gathering pipeline is v = 1.7 m / s, and the temperature T at the inner wall of the oil gathering pipeline is... w =20℃, the temperature of the medium surrounding the oil collecting pipeline T0 = 7℃, the absolute equivalent roughness e = 0.14mm. The heat transfer coefficient of the oil collecting pipeline K = 1.4W / (m²) 2 The oil gathering pipeline has an outer diameter D = 60 mm, a mass flow rate G = 3.2 kg / s of produced fluid, a specific heat capacity c = 2900 J / (kg·℃) at the average temperature of the oil gathering pipeline, an initial shear stress τ0 = 48.3 Pa at the pipeline wall, a gathering and transportation time t = 2 days, and a kinematic viscosity ω = 2.19 × 10⁻⁶. -4 m 2 / s.

[0176] For example, the fitting methods for the fitting parameters k, m, n in formula (3) and formula (14) and the fitting parameters d, e, f, g, h, i, j in formula (7) include:

[0177] For multiphase produced fluids from oilfields with different overall water cuts, wall adhesion tests were conducted to measure the wall adhesion temperature T. s Given the wall adhesion velocity Δ, and the annular channel material being the same as the pipeline material in the gathering and transportation method, the values ​​of k, m, n and the values ​​of d, e, f, g, h, i, j are determined by fitting.

[0178] Set up different comprehensive moisture contents (φ1, φ2, φ3... φ) n The oil-water mixture was tested using a pour point apparatus to measure the pour point (T) of the mixture with different water contents. GP1 ,T GP2 ,T GP3 ...T GPn The density of the mixture (ρ1, ρ2, ρ3...ρ) was measured using a hydrometer. n );

[0179] A loop test was conducted on the prepared crude oil emulsion. The loop was made of carbon steel, and the oil-water mixture was circulated within the pipeline to slowly cool the system. The test section had a pipe length of κ. When the test data showed a continuous increase in the pressure differential of the test section, the system temperature at this point was taken as the wall adhesion temperature (T) for mixtures with different water contents. s1 ,T s2 ,T s3 ...T sn According to formula (5), the shear stresses at the pipe wall are calculated as (τ1, τ2, τ3...τ). n The initial shear stress at the pipe wall is τ0, and the temperature at the pipe wall is T.w ;

[0180] After running for a period of time, record the pipeline pressure difference (ΔP1, ΔP2, ΔP3...ΔP) for oil-water mixtures with different water contents. n After running for a period of time Δt, record the pressure differences at this time as (ΔP′1, ΔP′2, ΔP′3...ΔP′). n );

[0181] Calculate the wall adhesion rate corresponding to different water contents of the mixture according to formula (15):

[0182]

[0183] In formula (15), v is the flow velocity of the oilfield produced fluid in the oil gathering pipeline (which is the flow velocity of the mixture in the loop test in formula (15)), in m / s; κ is the length of the test section pipe, in m; and a hydrometer is used to measure the density of the mixture (ρ1, ρ2, ρ3...ρ). n (Unit: kg / m³) 3 Δt represents the experimental run time in seconds; (ΔP1, ΔP2, ΔP3...ΔP n The unit of (ΔP′1, ΔP′2, ΔP′3...ΔP′) is Pa. n The unit of ) is Pa;

[0184] The calculated wall adhesion rates of oil-water mixtures with different water contents are (Δ1, Δ2, Δ3...Δ n );

[0185] According to the experimental data set (T) s1 ,T s2 ,T s3 ...T sn ), (T GP1 ,T GP2 ,T GP3 ...T GPn (φ1,φ2,φ3...φ) n (τ1,τ2,τ3...τ) n The least squares method was used to fit the formula for calculating the wall adhesion temperature (14): T s =T GP -kφ m τ n Determine the values ​​of the fitting parameters k, m, and n;

[0186] Based on the experimental data set (Δ1, Δ2, Δ3...Δ n (φ1,φ2,φ3...φ) n (τ1,τ2,τ3...τ) n ), (TGP1 ,T GP2 ,T GP3 ...T GPn ), and τ0, T w The least squares method was used to fit the formula for calculating the wall adhesion rate (7), and the values ​​of the fitting parameters d, e, f, g, h, i, and j were determined.

[0187] By conducting an experiment on the wall adhesion of solidified oil in a ring channel, the wall adhesion temperature was tested, and the fitting parameters k, m, and n were determined and are shown in Table 1. All of them are within the aforementioned range.

[0188] Table 1

[0189] Fitting parameters <![CDATA[k(℃·Pa -n )]]> m n numerical values 12.69 2.65 0.21

[0190] The wall adhesion rate was tested by conducting a solidification and adhesion ring test. The values ​​of fitting parameters d, e, f, g, h, i, and j were determined and are shown in Table 2. All of them are within the aforementioned range.

[0191] Table 2

[0192] Fitting parameters <![CDATA[d(m·s -1 ·Well -e ·℃ -j )]]> e f g h i j numerical values 0.002 -1.64 0.43 6.19 -0.93 -1.52 3.72

[0193] The fitting parameters a and b in formula (2) are fitted using the following experiments:

[0194] The yield stress of waxy crude oil increases exponentially with decreasing measurement temperature, conforming to formula (16):

[0195] τ y =exp(a-bT)……………………(16)

[0196] In the formula, τ y denoted as ρ, Pa; T is the yield stress of water-containing solidified oil adhering to the wall; and a and b are experimental fitting parameters.

[0197] By adjusting the temperature to test the yield stress of the oilfield produced fluid, the fitting parameters a and b in formula (2) were obtained. By adjusting the temperature to test the yield stress of the oilfield produced fluid, the fitting parameters a and b in formula (2) can be determined according to formula (16), as shown in Table 3, all of which are within the aforementioned range.

[0198] Table 3

[0199] Fitting parameters a b numerical values 8.19 0.12

[0200] Substitute the above parameters into formula (4) as needed to obtain the axial heat dissipation parameter ψ = 2.8 × 10⁻⁶ for the oil collection pipeline in formula (3). -5 m -1Substitute the above parameters into formula (5) as needed to obtain the shear stress τ = 49.7 Pa at the inner wall of the oil gathering pipeline in formula (3), and calculate the distance L1 = 377 m from the wellhead starting point at the position where the friction temperature drops to the wall adhesion temperature.

[0201] Substitute the above parameters into formula (7) as needed, and substitute the shear stress τ at the inner wall of the oil gathering pipeline calculated by formula (5) into formula (7) to obtain the wall adhesion velocity Δ=1.55mm / d;

[0202] Substitute the above parameters into formula (6) as needed, and import the parameter sticking speed Δ into formula (6) to calculate the sticking thickness δ of the sticking oil solidification section. The sticking thickness δ of the sticking oil solidification section is 3.1mm.

[0203] Substitute the above parameters into formulas (12) and (13) as needed to calculate the Reynolds number Re = 403.7 and the relative equivalent roughness of the pipe wall ε = 0.0054; based on the Reynolds number Re, the relative equivalent roughness of the pipe wall ε, and formulas (8) to (11), the hydraulic friction coefficient λ = 0.16 is calculated;

[0204] For example, such as Figure 2 As shown in this embodiment, the arc length of the oil adhesion section accounts for a certain percentage of the perimeter of the pipe's inner cross-section.

[0205] Substitute the above parameters into formulas (1), (2), and (1.1) as needed. Substitute the distance L1 = 377m from the wellhead starting point at the point where the friction temperature drops to the wall adhesion temperature obtained from formula (3) into formulas (1), (2), and (1.1). Substitute the wall adhesion thickness δ of the wall adhesion solidification section obtained from formula (6) and the hydraulic friction coefficient λ obtained from formulas (8) to (13) into formulas (1) and (1.1) to calculate the critical gathering and transportation temperature T1 = f -1 (F1) = 18℃;

[0206] Substitute the above parameters into formula (14) as needed, and substitute the shear stress τ at the inner wall of the oil gathering pipeline calculated by formula (5) into formula (14) to calculate the critical wall adhesion temperature T. s =30℃;

[0207] It is evident that the critical gathering and transportation temperature is nearly 12°C lower than the wall-adhesion temperature.

[0208] In the field experiment, the well was cooled for oil collection. First, the valves in the heating pipeline were adjusted to reduce the amount of hot water mixed in, lowering the return oil temperature to 4°C (22°C) and 2°C (20°C) above the critical gathering and transportation temperature, respectively, before conducting oil collection experiments. Changes in wellhead back pressure were monitored. Figure 5 As shown.

[0209] Under oil gathering conditions of 22℃, the effective flow area of ​​the pipeline is reduced due to the adhesion of condensed oil at the pipe wall, and the wellhead back pressure increases first and then stabilizes at around 1.3MPa; under oil gathering conditions of 20℃, the wellhead back pressure increases first and then stabilizes at around 2.2MPa.

[0210] Under both conditions, the wellhead back pressure did not exceed the maximum allowable wellhead back pressure of 3.2 MPa at the pipeline starting point, thus achieving safe oil collection and further reducing the gathering and transportation temperature by nearly 10°C from the critical wall adhesion temperature, thereby achieving energy saving and consumption reduction.

[0211] For example, the water cut of the X4-2-F17 single well in the Fourth Oilfield of Daqing Oilfield is 96.1%, which is within the range of ultra-high water cut. The wall adhesion temperature under the water cut of the operating conditions was measured to be 32℃. Through cooling tests, it was found that the ultra-high water cut crude oil of this single well can operate below the critical wall adhesion temperature, and the return oil temperature can be reduced to below the critical wall adhesion temperature (26℃) and operate normally.

[0212] When the temperature of the produced fluid in the oilfield drops below the critical wall-sticking temperature, the yield stress of the water-bearing condensate produced by the produced fluid increases rapidly. The shearing action of the pipe flow is insufficient to separate the water-bearing condensate from the pipe wall, causing the water-bearing condensate to continuously adhere inside the pipe. The condensate section gradually thickens, increasing friction along the pipe. The continuous oil inflow from the well bottom forms local blockages and accumulates in the very narrow effective pipe diameter, leading to an increase in the average wellhead back pressure. During pipeline operation, lumpy condensate continuously comes into contact with and adheres to the condensate section. As the wellhead back pressure increases, when the pressure increase generates a squeezing force that just overcomes the wall-sticking force generated by the yield stress of the condensate section, the lumpy condensate on the condensate section is flushed out of the pipeline, and the wellhead back pressure decreases again, exhibiting a periodic "restart" change. Therefore, when produced fluids are transported in the gathering pipeline, the balance between the pressure difference between the two ends of the gathering pipeline caused by the solidification and adhesion phenomenon, which leads to the squeezing force on the solidified section of the pipeline, and the adhesion force on the pipeline wall caused by the yield stress of the solidified section, is the key to ensuring the safe operation of produced fluids in the gathering pipeline below the critical adhesion temperature.

[0213] On the other hand, such as Figure 3 As shown, this disclosure provides an oilfield produced fluid gathering and transportation system, including the above-mentioned method for gathering and transporting oilfield produced fluids with extremely high water content. The system includes:

[0214] The first acquisition module 810 is used to acquire the following parameters: the maximum allowable back pressure P0 of the produced oil at the starting point of the oil gathering pipeline, the inner radius R of the oil gathering pipeline, the density ρ of the produced oil, the dynamic viscosity μ of the produced oil, the flow velocity v of the produced oil in the oil gathering pipeline, the inlet pressure P1 of the produced oil at the end of the oil gathering pipeline, the comprehensive water content φ of the produced oil, and the emulsified water content of the produced oil. The length L of the oil gathering pipeline from the wellhead to the inlet, and the pour point T of the oilfield produced fluid. GP The temperature T at the pipe wall of the oil collecting pipeline w Temperature T0 of the medium surrounding the oil gathering pipeline, absolute equivalent roughness e, heat transfer coefficient K of the oil gathering pipeline, outer diameter D of the oil gathering pipeline, mass flow rate G of the oilfield produced fluid, specific heat capacity c of the oilfield produced fluid at the average temperature of the oil gathering pipeline, gathering and transportation time t, initial shear stress τ0 at the pipe wall of the oil gathering pipeline, and kinematic viscosity ω of the produced fluid.

[0215] The second acquisition module 820 is used to calculate the critical gathering and transportation temperature of the oilfield produced fluid using formulas (1) to (13) and formulas (15) to (16); and to calculate the critical wall adhesion temperature of the oilfield produced fluid using formulas (14) and (15).

[0216] The third acquisition module 830 is used to determine the target gathering and transportation temperature of the oilfield produced fluid based on the critical gathering and transportation temperature of the oilfield produced fluid; the target gathering and transportation temperature of the oilfield produced fluid is greater than the critical gathering and transportation temperature of the oilfield produced fluid and less than the critical wall adhesion temperature of the oilfield produced fluid.

[0217] The gathering and transportation module 840 is used to gather and transport the oilfield produced fluid at the target gathering and transportation temperature. In the above embodiments of the gathering and transportation system for oilfield produced fluid with extremely high water content, the specific processing of each module and its resulting technical effects can be found in the relevant descriptions in the corresponding method embodiments, and will not be repeated here.

[0218] In another aspect, this disclosure provides an electronic device including a memory and a processor, the memory storing a computer program, and the processor executing the method as described above when running the computer program.

[0219] In another aspect, this disclosure provides a storage medium for storing a computer-readable program, which, when run, performs the methods described above.

[0220] Figure 4 This is an exemplary structural diagram of an electronic device according to some embodiments of the present disclosure.

[0221] like Figure 4As shown, the electronic device includes: at least one processor 901, at least one communication interface 902, at least one memory 903, and at least one communication bus 904. Optionally, the communication interface 902 can be an interface for a communication module, such as the interface for a GSM module. The processor 901 may be a CPU, an Application Specific Integrated Circuit (ASIC), or one or more integrated circuits configured to implement the embodiments of this disclosure. The memory 903 may include high-speed RAM and may also include non-volatile memory, such as at least one disk storage device. The memory 903 stores a program, and the processor 901 calls the program stored in the memory 903 to execute some or all of the above-described method embodiments.

[0222] This disclosure relates to a storage medium for storing a computer-readable program, which, when run, performs some or all of the method embodiments described above.

[0223] Optionally, the storage medium may be a non-transitory computer-readable storage medium, such as a ROM, random access memory (RAM), CD-ROM, magnetic tape, floppy disk, and optical data storage device.

[0224] Based on the same inventive concept, this disclosure also provides a computer program product, including a computer program that, when executed by a processor, implements some or all of the above-described method embodiments.

[0225] The basic concepts have been described above. It is obvious that the detailed disclosure above is merely illustrative and does not constitute a limitation of this disclosure. Although not explicitly stated herein, various modifications, improvements, and corrections may be made to this disclosure by those skilled in the art. Such modifications, improvements, and corrections are suggested in this disclosure and therefore remain within the spirit and scope of the exemplary embodiments of this disclosure.

[0226] Furthermore, this disclosure uses specific terms to describe embodiments of the present disclosure. For example, "an embodiment," "one embodiment," and / or "some embodiments" refer to a particular feature, structure, or characteristic associated with at least one embodiment of the present disclosure. Therefore, it should be emphasized and noted that "an embodiment," "one embodiment," or "an alternative embodiment" mentioned twice or more in different locations in this disclosure do not necessarily refer to the same embodiment. In addition, certain features, structures, or characteristics in one or more embodiments of the present disclosure can be appropriately combined.

[0227] Furthermore, unless expressly stated in the claims, the order of processing elements and sequences, the use of numbers and letters, or other names described in this disclosure are not intended to limit the order of the processes and methods of this disclosure. Although various examples have been discussed in the foregoing disclosure of some embodiments that are currently considered useful, it should be understood that such details are for illustrative purposes only, and the appended claims are not limited to the disclosed embodiments; rather, the claims are intended to cover all modifications and equivalent combinations that conform to the spirit and scope of the embodiments of this disclosure. For example, while the system components described above can be implemented by hardware devices, they can also be implemented solely by software solutions, such as installing the described system on existing servers or mobile devices.

[0228] Similarly, it should be noted that, in order to simplify the description of this disclosure and thus aid in the understanding of one or more embodiments of the invention, the foregoing description of embodiments of this disclosure may sometimes combine multiple features into a single embodiment, drawing, or description thereof. However, this disclosure method does not imply that the subject matter of this disclosure requires more features than those mentioned in the claims. In fact, the embodiments contain fewer features than all the features of a single embodiment disclosed above.

[0229] In some embodiments, numbers describing the quantity of components and attributes are used. It should be understood that such numbers used in the description of embodiments are modified in some examples with the terms "approximately," "approximately," or "generally." Unless otherwise stated, "approximately," "approximately," or "generally" indicates that the numbers are allowed to vary by ±20%. Accordingly, in some embodiments, the numerical parameters used in the specification and claims are approximate values, which may be changed depending on the characteristics required by individual embodiments. In some embodiments, numerical parameters should take into account specified significant digits and employ a general method of digit reservation. Although the numerical ranges and parameters used to confirm their breadth of range in some embodiments of this disclosure are approximate values, in specific embodiments, such values ​​are set as precisely as feasible.

[0230] For each patent, patent application, patent application publication, and other material such as articles, books, specifications, publications, and documents referenced in this disclosure, the entire contents of that publication are incorporated herein by reference. This excludes historical application documents that are inconsistent with or conflict with this disclosure, as well as documents that limit the broadest scope of the claims of this disclosure (currently or subsequently appended to this disclosure). It should be noted that in the event of any inconsistency or conflict between the descriptions, definitions, and / or terminology used in the supplementary materials to this disclosure and the content of this disclosure, the descriptions, definitions, and / or terminology used in this disclosure shall prevail.

[0231] Finally, it should be understood that the embodiments described in this disclosure are merely illustrative of the principles of the embodiments of this disclosure. Other variations may also fall within the scope of this disclosure. Therefore, alternative configurations of the embodiments of this disclosure are considered as examples and not limitations, and are regarded as consistent with the teachings of this disclosure. Accordingly, the embodiments of this disclosure are not limited to those explicitly described and illustrated herein.

Claims

1. A method for gathering and transporting produced fluid from an oilfield with extremely high water content, characterized in that, The method includes: The target gathering and transportation temperature of the oilfield produced fluid is set to be greater than the critical gathering and transportation temperature of the oilfield produced fluid and less than the critical wall adhesion temperature of the oilfield produced fluid. The critical gathering and transportation temperature of the oilfield produced fluid is the gathering and transportation temperature at which the adhesion force of the wall-adhering water-containing solidified oil section formed by the accumulation of the oilfield produced fluid along the oil gathering pipeline on the pipeline wall is equal to the top-squeezing force of the oilfield produced fluid on the wall-adhering solidified oil section. The method for obtaining the critical gathering and transportation temperature T1 includes the following steps: Get the following parameters: The maximum allowable back pressure P0 of the produced fluid at the starting point of the gathering pipeline, the inner radius R of the gathering pipeline, the density P of the produced fluid, the dynamic viscosity μ of the produced fluid, the flow velocity v of the produced fluid in the gathering pipeline, the inlet pressure P1 of the produced fluid at the end of the gathering pipeline, the overall water cut φ of the produced fluid, and the emulsified water cut of the produced fluid. The length L of the oil gathering pipeline from the wellhead to the inlet, and the pour point T of the oilfield produced fluid. GP The temperature T at the pipe wall of the oil collecting pipeline w Temperature T0 of the medium surrounding the oil gathering pipeline, absolute equivalent roughness e, heat transfer coefficient K of the oil gathering pipeline, outer diameter D of the oil gathering pipeline, mass flow rate G of the oilfield produced fluid, specific heat capacity c of the oilfield produced fluid at the average temperature of the oil gathering pipeline, gathering and transportation time t, initial shear stress τ0 at the pipe wall of the oil gathering pipeline, and kinematic viscosity ω of the oilfield produced fluid. The critical gathering and transportation temperature T1 is calculated according to formula (1): In formula (1), P0 is the maximum allowable back pressure of the oilfield produced fluid at the starting point of the gathering pipeline, in Pa; λ is the hydraulic friction coefficient, dimensionless; L1 is the distance from the wellhead starting point where the friction temperature drops to the wall adhesion temperature, in m; R is the inner radius of the gathering pipeline, in m; and ρ is the density of the oilfield produced fluid, in kg / m³. 3 v is the flow velocity of the produced fluid in the oil gathering pipeline, in m / s; P1 is the inlet pressure of the produced fluid at the end of the oil gathering pipeline, in Pa; δ is the wall thickness of the sticky solidification section, in m; φ is the overall water content of the produced fluid, %. Emulsion water content of produced fluid from the oilfield, in %; In formula (1), f -1 (F1) is the inverse function of F1 = f(T1), and the original function F1 = f(T1) is shown in formula (2): In formula (2), R is the inner radius of the oil gathering pipeline, in meters; φ is the comprehensive water content of the produced fluid from the oilfield, in percent. L1 is the emulsified water content of the produced fluid, in %; L2 is the distance from the wellhead starting point to the point where the friction temperature drops to the wall-sticking temperature, in meters; L3 is the distance from the end of the pipeline to the point where the friction temperature drops to the wall-sticking temperature (L2 = L - L1), in meters; L is the length of the oil gathering pipeline from the wellhead to the inlet, in meters; T0 is the temperature of the medium surrounding the oil gathering pipeline, in degrees Celsius; ψ is the axial heat dissipation parameter of the oil gathering pipeline, in meters. -1 ; l is the distance from the starting point of the integral infinitesimal segment of the oil collecting pipeline dl to the pipeline; the oil temperature on the infinitesimal segment of the oil collecting pipeline dl is T; a and b are fitting parameters, determined experimentally. In formula (1), the distance L1 from the wellhead starting point to the location where the friction temperature drops to the wall adhesion temperature is calculated according to formula (3): In formula (3), L is the length of the oil gathering pipeline from the wellhead to the inlet, in meters; ψ is the axial heat dissipation parameter of the oil gathering pipeline, in meters. -1 ;T GP φ is the pour point of the produced fluid in the oilfield, in °C; φ is the overall water content of the produced fluid in the oilfield, in %; τ is the shear stress at the inner wall of the oil gathering pipeline, in Pa; T0 is the temperature of the medium surrounding the oil gathering pipeline, in °C. k, m, and n are fitting parameters, which are determined based on experiments; The axial heat dissipation parameter ψ of the oil gathering pipeline in formula (3) is calculated according to formula (4): In formula (4), K is the heat transfer coefficient of the oil gathering pipeline, with units of W / (m). 2 ·℃); D is the outer diameter of the oil gathering pipeline, in m; G is the mass flow rate of the produced fluid from the oilfield, in kg / s; c is the specific heat capacity of the produced fluid from the oilfield at the average temperature of the oil gathering, in J / (kg·℃); The shear stress τ at the inner wall of the oil gathering pipeline in formula (3) is calculated according to formula (5): In formula (5), μ is the dynamic viscosity of the oilfield produced fluid, in Pa·s; R is the inner radius of the oil gathering pipeline, in m; v is the flow velocity of the oilfield produced fluid in the oil gathering pipeline, in m / s; In formula (1), the wall adhesion thickness δ of the wall-adhering solidification section is calculated according to formula (6): In formula (6), t is the collection and transportation time, in d; Δ is the wall adhesion velocity, in mm / d; In formula (6), the wall-adhesion velocity Δ is calculated according to formula (7): In formula (7), τ0 is the initial shear stress at the pipe wall of the oil gathering pipeline, in Pa; φ is the comprehensive water cut of the produced fluid in the oilfield, %; τ is the shear stress at the inner wall of the oil gathering pipeline, in Pa; T GP T is the pour point of the produced fluid from the oilfield, expressed in °C. w The temperature at the pipe wall of the oil gathering pipeline is expressed in °C; d, e, f, g, h, i, and j are fitting parameters determined experimentally. In formula (1), the hydraulic friction coefficient λ is calculated according to formulas (8), (9), (10), and (11): Laminar flow region: Hydraulically smooth zone: Mixed friction zone: Rough area: In formulas (8), (9), (10), and (11), Re is the Reynolds number, ε is the relative equivalent roughness of the pipe wall (dimensionless), and e represents the absolute equivalent roughness (in meters). Formula (8) is applicable when Re < 2000, and formula (9) is applicable when... The applicable conditions for formula (10) are as follows: The applicable conditions for formula (11) are as follows: In formulas (8), (9), (10), and (11), the Reynolds number Re is calculated according to formula (12), and the relative equivalent roughness ε of the pipe wall is calculated according to formula (13): In formula (12), ω represents the kinematic viscosity of the produced fluid, m 2 / s; v is the flow velocity of the produced fluid in the oilfield in the oil gathering pipeline; R is the inner radius of the oil gathering pipeline, in meters; In formula (13), e is the absolute equivalent roughness in m; R is the inner radius of the oil gathering pipeline in m.

2. The method according to claim 1, characterized in that, The fitting method for the fitting parameters k, m, and n in formula (3) is as follows: For multiphase produced fluids from oilfields with different comprehensive water cuts, the wall adhesion temperature T is tested by conducting solidification wall adhesion annular experiments. s The freezing point T was tested using a freezing point apparatus. GP The values ​​of k, m, and n are determined by fitting the data. The value of k ranges from 5.31℃·Pa. -n Up to 17.94℃·Pa -n The value of m ranges from 1.71 to 5.43; the value of n ranges from 0.19 to 0.

67. The k value increases with the increase of oil phase wax content in the multiphase produced fluid of the oilfield, while the m and n values ​​decrease with the increase of oil phase wax content in the multiphase produced fluid of the oilfield.

3. The method according to claim 1, characterized in that, The fitting method for the fitting parameters d, e, f, g, h, i, j in formula (5) is as follows: For multiphase produced fluids from oilfields with different comprehensive water content, conduct a wall adhesion test in the oil-condensing and wall-adhesion annular channel to test the wall adhesion rate Δ, and fit and determine the values ​​of d, e, f, g, h, i, j. The value of d ranges from 0.001 m·s. -1 ·Pa -e ·℃ -j up to 0.03 m·s -1 ·Pa -e ·℃ -j The values ​​of e range from -1.91 to -0.53; the values ​​of f range from 0.37 to 0.99; the values ​​of g range from 4.27 to 8.63; the values ​​of h range from -0.99 to -0.03; the values ​​of i range from -2.14 to -0.99; and the values ​​of j range from 1.75 to 4.

99. The values ​​of d, e, h, and i increase with the increase of wax content in the oil phase of multiphase produced fluids from oilfields; The values ​​of f, g, and j decrease as the wax content of the oil phase in the multiphase produced fluid of the oilfield increases.

4. The method according to any one of claims 1 to 3, characterized in that, The method for obtaining the critical wall-sticking temperature includes the following steps: Obtain the following parameters: Pour point T of the oilfield produced fluid. GP The overall water cut φ of the produced fluid from the oilfield, and the shear stress τ at the inner wall of the oil gathering pipeline. The critical wall adhesion temperature T s Calculate according to formula (14): T s =T GP -kφ m τ n …………………………(14) In formula (14), T GP φ is the pour point of the produced fluid in the oilfield, in °C; φ is the overall water content of the produced fluid in the oilfield; τ is the shear stress at the inner wall of the oil gathering pipeline, in Pa. k, m, and n are fitting parameters, which are the same as the fitting parameters k, m, and n in formula (2).

5. The method according to claim 4, characterized in that, The fitting methods for the fitting parameters k, m, n in formula (3) and formula (14) and the fitting parameters d, e, f, g, h, i, j in formula (7) include: For multiphase produced fluids from oilfields with different overall water cuts, wall adhesion tests were conducted to measure the wall adhesion temperature T. s Using the wall adhesion velocity Δ, the values ​​of k, m, n and the values ​​of d, e, f, g, h, i, j are determined by fitting the data. Set up different comprehensive moisture contents (φ1, φ2, φ3... φ) n The oil-water mixture was tested using a pour point apparatus to measure the pour point (T) of the mixture with different water contents. GP1 ,T GP2 ,T GP3 ...T GPn The density of the mixture (ρ1, ρ2, ρ3...ρ) was measured using a hydrometer. n ); A loop test was conducted on the prepared crude oil emulsion, allowing the oil-water mixture to circulate within the pipeline while the system was slowly cooled. The test section had a pipe length of κ. When the test data showed a continuous increase in the pressure differential within the test section, the system temperature at this point was identified as the wall adhesion temperature (T) for mixtures with different water contents. s1 ,T s2 ,T s3 ...T sn According to formula (5), the shear stresses at the pipe wall are calculated as (τ1, τ2, τ3...τ). n The initial shear stress at the pipe wall is τ0, and the temperature at the pipe wall is T. w ; After running for a period of time, record the pipeline pressure difference (ΔP1, ΔP2, ΔP3...ΔP) for oil-water mixtures with different water contents. n After running for a period of time Δt, record the pressure differences at this time as (ΔP1′, ΔP2′, ΔP3′...ΔP). n ′); Calculate the wall adhesion rate corresponding to different water contents of the mixture according to formula (15): In formula (15), v is the flow velocity of the oilfield produced fluid in the oil gathering pipeline (which is the flow velocity of the mixture in the loop test in formula (15)), in m / s; κ is the length of the test section pipe, in m; and a hydrometer is used to measure the density of the mixture (ρ1, ρ2, ρ3...ρ). n (Unit: kg / m³) 3 λ is the hydraulic friction coefficient, dimensionless; Δt is the experimental running time, in seconds; (ΔP1, ΔP2, ΔP3...ΔP n The unit of (ΔP1′, ΔP2′, ΔP3′...ΔP) is Pa. n The unit of (′) is Pa; The calculated wall adhesion rates of oil-water mixtures with different water contents are (Δ1, Δ2, Δ3...Δ n ); According to the experimental data set (T) s1 ,T s2 ,T s3 ...T sn ), (T GP1 ,T GP2 ,T GP3 ...T GPn (φ1,φ2,φ3...φ) n (τ1,τ2,τ3...τ) n The least squares method was used to fit the formula for calculating the wall adhesion temperature (14): T s =T GP -kφ m τ n Determine the values ​​of the fitting parameters k, m, and n; Based on the experimental data set (Δ1, Δ2, Δ3...Δ n (φ1,φ2,φ3...φ) n (τ1,τ2,τ3...τ) n ), (T GP1 ,T GP2 ,T GP3 ...T GPn ), and τ0, T w The least squares method was used to fit the formula for calculating the wall adhesion rate (7), and the values ​​of the fitting parameters d, e, f, g, h, i, and j were determined.

6. The method according to claim 5, characterized in that, The fitting parameters a and b in formula (2) are fitted according to formula (16): τ y =exp(a-bT)……………………………(16) In the formula, τ y is the yield stress of water-containing solidified oil adhering to the wall, Pa; T is the yield stress test temperature, °C; a and b are experimental fitting parameters; By adjusting the temperature, the yield stress of the oilfield produced fluid was experimentally tested, and the fitting parameters a and b in formula (2) were obtained by fitting. The value of a ranges from 5.72 to 43.69; the value of b ranges from 0.01 to 0.

97. The value of a increases with the increase of the wax content in the oil phase of the multiphase produced fluid in the oilfield, while the value of b decreases with the increase of the wax content in the oil phase of the multiphase produced fluid in the oilfield.

7. The method according to any one of claims 1 to 3, characterized in that, The water content of the produced fluid from the ultra-high water-cut oilfield is 70% to 99%.

8. A gathering and transportation system for oilfield produced fluids, comprising the gathering and transportation method for oilfield produced fluids with ultra-high water content as described in claim 6, characterized in that, The system includes: The first acquisition module is used to acquire the following parameters: the maximum allowable back pressure P0 of the produced fluid at the starting point of the gathering pipeline, the inner radius R of the gathering pipeline, the density ρ of the produced fluid, the dynamic viscosity μ of the produced fluid, the flow velocity v of the produced fluid in the gathering pipeline, the inlet pressure P1 of the produced fluid at the end of the gathering pipeline, the comprehensive water content φ of the produced fluid, and the emulsified water content of the produced fluid. The length L of the oil gathering pipeline from the wellhead to the inlet, and the pour point T of the oilfield produced fluid. GP The temperature T at the pipe wall of the oil collecting pipeline w Temperature T0 of the medium surrounding the oil gathering pipeline, absolute equivalent roughness e, heat transfer coefficient K of the oil gathering pipeline, outer diameter D of the oil gathering pipeline, mass flow rate G of the oilfield produced fluid, specific heat capacity c of the oilfield produced fluid at the average temperature of the oil gathering pipeline, gathering and transportation time t, initial shear stress τ0 at the pipe wall of the oil gathering pipeline, and kinematic viscosity ω of the produced fluid. The second acquisition module is used to calculate the critical gathering and transportation temperature of the oilfield produced fluid using formulas (1) to (13) and formulas (15) to (16); and to calculate the critical wall adhesion temperature of the oilfield produced fluid using formulas (14) and (15). The third acquisition module is used to determine the target gathering and transportation temperature of the oilfield produced fluid based on the critical gathering and transportation temperature of the oilfield produced fluid; the target gathering and transportation temperature of the oilfield produced fluid is greater than the critical gathering and transportation temperature of the oilfield produced fluid and less than the critical wall adhesion temperature of the oilfield produced fluid. The gathering and transportation module is used to gather and transport the produced fluid from the oilfield at the target gathering and transportation temperature.

9. An electronic device comprising a memory and a processor, the memory storing a computer program, the processor executing the method of claim 6 when running the computer program.

10. A storage medium for storing a computer-readable program, which, when executed, performs the method of claim 6.

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