A method and system for calculating flow skin for a sliding sleeve completion string

Abstract

The application relates to a sliding sleeve completion pipe string flow skin calculation method and system, which is characterized by comprising the following steps: according to the pressure distribution characteristics in the flow process of the sliding sleeve completion pipe string, the flow area of the reservoir fluid is divided; the boundary of the linear flow area in the flow area is determined based on the geometric boundary; the boundary of the radial flow area in the flow area is determined based on the geometric boundary and the roundness; and the skin coefficient caused by the near wellbore zone of the sliding sleeve completion pipe string is determined according to the pressure drop difference of the reservoir fluid through the sliding sleeve completion pipe string and the open hole well based on the divided flow area and the determined boundary. The application can be widely applied in the technical field of completion pipe strings.

Description

Technical Field

[0001] This invention relates to the field of well completion string technology, and in particular to a method and system for calculating the flow skin of a sliding sleeve well completion string. Background Technology

[0002] Horizontal wells offer a large control area, low production pressure differential, and high output. However, due to factors such as the heel-toe effect, reservoir heterogeneity, and uneven injection and production, horizontal wells are prone to localized water coning, which can lead to water flooding in severe cases. This water flooding phenomenon becomes more pronounced in the mid-to-late stages of oil well development. To effectively mitigate the problem of premature water breakthrough in oil wells, existing technologies disclose variable-density perforation completion methods, center-tube completion methods, inflow control device completion methods, and sliding sleeve-based control valve completion methods.

[0003] Sliding sleeve-based control valve completion methods allow for unlimited adjustment and real-time control of the sliding sleeve opening, ensuring balanced inflow most effectively and enabling local shut-in as needed. Accurate characterization of the sliding sleeve-reservoir flow and rapid prediction of reservoir inflow dynamics help guide adjustments to the sliding sleeve opening.

[0004] However, the small size, complex structure, and complex internal flow of the sliding sleeve cause significant interference to the flow in the wellbore and around the well, increasing the difficulty of calculating and predicting the skin surface of the near-wellbore zone in the sliding sleeve completion string. There is also no effective method for calculating the flow skin surface of the sliding sleeve completion string in the existing technology. Summary of the Invention

[0005] To address the aforementioned problems, the purpose of this invention is to provide a method and system for calculating the flow skin of a sliding sleeve completion string, which can effectively and uniformly characterize the reservoir-sliding sleeve flow system in the near-wellbore zone.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: Firstly, it provides a method for calculating the flow skin of a sliding sleeve completion string, comprising:

[0007] Based on the pressure distribution characteristics during the flow process of the sliding sleeve completion string, the flow zone of the reservoir fluid is divided.

[0008] Based on geometric boundaries, determine the boundaries of linear flow regions within the flow region;

[0009] Based on geometric boundaries and roundness, determine the boundary of the radial flow region in the flow region;

[0010] Based on the defined flow zones and boundaries, the skin coefficient caused by the sliding sleeve completion string in the near-wellbore zone is determined according to the pressure drop difference between the reservoir fluid passing through the sliding sleeve completion string and the open hole.

[0011] Furthermore, the flow regions of the reservoir fluid include a linear flow region within the sliding sleeve orifice, a linear flow region within the slit, a radial flow region caused by a single slit, a radial flow region caused by a slit unit, a radial flow region away from the slit screen tube, and a converging flow region caused by the sliding sleeve orifice.

[0012] Furthermore, the linear flow region is:

[0013]

[0014] Where dp / ds is the pressure gradient along the streamline direction; dp / dn is the pressure gradient along the streamline normal direction; C0 is the critical value for the transition from linear flow to radial flow; p is the pressure; s is the displacement in the streamline tangential direction; and n is the displacement in the streamline normal direction.

[0015] The radial flow region is:

[0016]

[0017] Furthermore, the lower boundary 'a' of the linear flow region in the flow region is:

[0018]

[0019] in, This represents the minimum pressure value in the linear flow region. The pressure whose ratio of the tangential pressure gradient to the normal pressure gradient along the streamline is less than the critical value of transformation.

[0020] The upper boundary b of the linear flow region in the flow region is:

[0021]

[0022] in, This represents the maximum pressure value in the linear flow region.

[0023] Furthermore, the upper boundary c of the radial flow region in the flow region is:

[0024]

[0025] in, The average radius of the same pressure contour lines in the radial flow region;

[0026] The lower boundary d of the radial flow region in the flow region is:

[0027]

[0028] Where D0 is the characteristic length of the orifice or slit that causes radial flow.

[0029] Furthermore, based on the defined flow regions and boundaries, and according to the pressure drop difference between the reservoir fluid passing through the sliding sleeve completion string and the open hole, the skin coefficient caused by the sliding sleeve completion string in the near-wellbore zone is determined, including:

[0030] Based on the flow characteristics and defined boundaries of the linear flow region within the slit, the radial flow region caused by a single slit, the radial flow region caused by a slit unit, and the radial flow region far from the slit screen tube in the defined flow region, the corresponding skin coefficient is established.

[0031] Based on the linear flow region within the sleeve orifice in the defined flow region, the flow characteristics of the converging flow region caused by the sleeve orifice, and the defined boundary, the corresponding skin coefficient is established.

[0032] The skin coefficient of the sliding sleeve completion string in the near-wellbore zone is obtained based on the skin coefficients of the linear flow region within the slot, the radial flow region caused by a single slot, the radial flow region caused by a slot unit, the radial flow region far from the slotted screen, the linear flow region within the sliding sleeve orifice, and the converging flow region caused by the sliding sleeve orifice.

[0033] Furthermore, the skin coefficient s of the linear flow region within the cut... sl for:

[0034]

[0035] Among them, t Ds n is the dimensionless thickness of the slotted screen tube; s m is the number of slits within a slit unit. s The density of the slit elements in the circumferential direction; w Ds K represents the dimensionless width of the kerf element. Ds λ is the dimensionless permeability within the kerf; λ is the kerf penetration ratio.

[0036] The skin coefficient S of the radial flow region caused by the single cut sr for:

[0037]

[0038] Where L is the length of the sliding sleeve completion string; l u The length of the kerf unit; l s The kerf length;

[0039] The skin coefficient S of the radial flow region caused by the slit unit ur for:

[0040] or

[0041]

[0042] Where γ is the flow coefficient generated along the wellbore axis; w u r is the kerf element width; h is the kerf distance; h is the thickness of the radial flow caused by the kerf element; v is a parameter.

[0043] The skin coefficient S of the radial flow region away from the slotted screen tube ar for:

[0044] or

[0045]

[0046] Where, r w r is the radius of the slotted screen tube; b The outer diameter is located away from the radial flow region of the slotted screen tube;

[0047] The skin coefficient s of the linear flow region within the sleeve orifice Hl for:

[0048]

[0049] Among them, t s The thickness of the sliding sleeve string is given by m; K is the average reservoir permeability; m sH The density of the circumferential sliding sleeve; w sH K is the width of the sliding sleeve. H The permeability of the sliding sleeve orifice;

[0050] The skin coefficient S of the convergence flow area caused by the sliding sleeve orifice Hr for:

[0051]

[0052] Where, r c r0 is the upper boundary of the converging flow at the sliding sleeve orifice; r0 is the lower boundary of the converging flow at the sliding sleeve orifice; A is the total open area of ​​the slotted screen tube; h H2 This refers to the axial spacing of the sleeve holes;

[0053] The skin coefficient S caused by the sliding sleeve completion string in the near-wellbore zone is:

[0054] S = s sl +S sr +S ur +S ar +S Hr +S Hr .

[0055] Secondly, a system for calculating the skin flow of a sliding sleeve completion string is provided, including:

[0056] The flow zone division module is used to divide the flow zone of reservoir fluid based on the pressure distribution characteristics during the flow process of the sliding sleeve completion string.

[0057] The linear flow region boundary determination module is used to determine the boundary of the linear flow region within the flow region based on the geometric boundary.

[0058] The radial flow region boundary determination module is used to determine the boundary of the radial flow region in the flow region based on the geometric boundary and roundness.

[0059] The skin coefficient determination module is used to determine the skin coefficient caused by the sliding sleeve completion string in the near-wellbore zone based on the defined flow area and the defined boundary, according to the pressure drop difference between the reservoir fluid passing through the sliding sleeve completion string and the open hole.

[0060] Thirdly, a processing device is provided, including computer program instructions, wherein when the computer program instructions are executed by the processing device, they are used to implement the steps corresponding to the above-mentioned sliding sleeve completion string flow skin calculation method.

[0061] Fourthly, a computer-readable storage medium is provided, wherein computer program instructions are stored on the computer-readable storage medium, wherein when the computer program instructions are executed by a processor, they are used to implement the steps corresponding to the above-described method for calculating the flow skin of the sliding sleeve completion string.

[0062] The present invention has the following advantages due to the adoption of the above technical solutions:

[0063] 1. This invention divides the flow region based on the pressure distribution characteristics during the flow process of the sliding sleeve completion string, determines the pressure gradient along the streamline direction and the pressure gradient along the normal direction of the streamline, and then integrates the two to determine the critical value of the transition between linear flow and radial flow. This makes the flow division, which is difficult to study in the Cartesian coordinate system, possible in streamline coordinates, and thus can more accurately characterize the flow characteristics of linear flow and radial flow.

[0064] 2. The skin coefficient of this invention is determined based on the pressure drop difference between the fluid passing through the sliding sleeve completion string and the open hole well. It has strong versatility and high calculation efficiency.

[0065] 3. Based on the characteristics of different flow regions, this invention establishes skin coefficient models for different regions, which can effectively and uniformly characterize the influence of sliding sleeve completion string structure on near-wellbore flow. This allows for accurate description of reservoir fluid flow behavior in the near-wellbore zone, providing theoretical guidance for the effective development of oil reservoir resources, thereby improving development efficiency and saving development costs.

[0066] In summary, this invention can be widely applied in the field of well completion tubing technology. Attached Figure Description

[0067] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts. In the drawings:

[0068] Figure 1 This is a schematic diagram of a method flow provided in an embodiment of the present invention;

[0069] Figure 2 This is a schematic diagram of complex flow near a wellbore provided in an embodiment of the present invention;

[0070] Figure 3 This is a schematic diagram of a sliding sleeve structure provided in an embodiment of the present invention;

[0071] Figure 4 This is a schematic diagram of various flow zones in the near-wellbore area of ​​a wellbore sliding sleeve tubing string provided in an embodiment of the present invention;

[0072] Figure 5 This is a schematic diagram of determining the radial flow boundary by combining geometric boundaries and roundness according to an embodiment of the present invention;

[0073] Figure 6 This is a schematic diagram of the near-wellbore flow of a sand-resistant slotted screen pipe provided in an embodiment of the present invention;

[0074] Figure 7 This is a schematic diagram of the flow inside the sliding sleeve and between the sliding sleeve and the wellbore annulus according to an embodiment of the present invention, wherein, Figure 7 (a) is a schematic diagram of the inside of the sliding sleeve. Figure 7 (b) is a schematic diagram of the annulus between the wellbore and the shaft. Detailed Implementation

[0075] Exemplary embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the invention and to fully convey the scope of the invention to those skilled in the art.

[0076] It should be understood that the terminology used herein is for the purpose of describing particular exemplary embodiments only and is not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “described” as used herein may also include the plural forms. The terms “comprising,” “including,” “containing,” and “having” are inclusive and therefore indicate the presence of the stated features, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components, and / or combinations thereof. The method steps, processes, and operations described herein are not construed as requiring them to be performed in a particular order described or illustrated unless the order of performance is explicitly indicated. It should also be understood that additional or alternative steps may be used.

[0077] Although terms such as first, second, third, etc., may be used in this document to describe multiple elements, components, regions, layers, and / or segments, these elements, components, regions, layers, and / or segments should not be limited by these terms. These terms may be used only to distinguish one element, component, region, layer, or segment from another. Unless the context clearly indicates otherwise, terms such as "first," "second," and other numerical terms used herein do not imply order or sequence. Therefore, the first element, component, region, layer, or segment discussed below may be referred to as the second element, component, region, layer, or segment without departing from the teachings of the exemplary embodiments.

[0078] The method and system for calculating the flow skin of a sliding sleeve completion string provided in this invention divides the flow region according to the pressure distribution characteristics during the flow process of the sliding sleeve completion string; determines the linear flow boundary based on the geometric boundary; determines the radial flow boundary by combining the geometric boundary and roundness; and determines the skin coefficient based on the pressure drop difference between the fluid passing through the sliding sleeve completion string and the open hole. This enables the identification of flow characteristics and the calculation of flow resistance in different regions, which helps guide the design of screen pipes and sliding sleeves, reduces the resistance of fluid passing through the reservoir, screen pipes, sliding sleeves, and wellbore, and improves oil well productivity.

[0079] Example 1

[0080] like Figure 1 As shown in the figure, this embodiment provides a method for calculating the flow skin of a sliding sleeve completion string, including the following steps:

[0081] 1) Based on the pressure distribution characteristics during the flow process of the sliding sleeve completion string, the flow zone of the reservoir fluid is divided.

[0082] 2) Determine the boundary of the linear flow region in the flow region based on the geometric boundary.

[0083] 3) Determine the boundary of the radial flow region in the flow region based on the geometric boundary and roundness.

[0084] 4) Based on the defined flow zones and boundaries, determine the skin coefficient caused by the sliding sleeve completion string in the near-wellbore zone according to the pressure drop difference between the reservoir fluid passing through the sliding sleeve completion string and the open hole.

[0085] In step 1) above, if Figure 2 The diagram shows a schematic of a sliding sleeve completion string, in which the outer layer of the horizontal wellbore uses a slotted screen for completion, and the inner layer is tubing with a sliding sleeve.

[0086] Specifically, such as Figure 3 As shown, the outer diameter of the sliding sleeve tool is 134mm, the inner diameter is 104mm, and the sliding sleeve tool has three rows of holes arranged circumferentially, with four holes symmetrically arranged in each row. The dimensions of each row of holes are as follows:

[0087] Row 1: 6mm long, 12mm wide, with rounded chamfers at both ends, 6mm in diameter.

[0088] 2nd row: 10mm long, 20mm wide, with rounded chamfers at both ends, 10mm in diameter.

[0089] 3rd row: 20mm long, 20mm wide, with four rounded chamfers of 10mm diameter.

[0090] This design allows for different sliding sleeve opening degrees by adjusting the position of the sliding sleeve. There are six ways to adjust the opening degree of the sliding sleeve joint holes: fully open, only the first row open, only the first and second rows open, only the second and third rows open, only the third row open, and fully closed.

[0091] Specifically, such as Figure 4 As shown, reservoir fluid gradually converges radially from the far end of the reservoir towards the slotted screen, then flows linearly through the slotted screen into the annulus between the slotted screen and the sliding sleeve. It then converges radially towards the sliding sleeve orifice, and finally flows linearly through the sliding sleeve orifice into the wellbore. Based on the flow characteristics of different regions, and according to the pressure distribution characteristics during the flow process of the sliding sleeve completion string, the flow regions of the reservoir fluid are divided. The flow regions of the reservoir fluid include the linear flow region within the sliding sleeve orifice, the linear flow region within the slots, the radial flow region caused by a single slot, the radial flow region caused by a slot unit, the radial flow region far from the slotted screen, and the converging flow region caused by the sliding sleeve orifice.

[0092] Specifically, the linear flow region is:

[0093]

[0094] Where dp / ds is the pressure gradient along the streamline direction, in Pa / m; dp / dn is the pressure gradient along the streamline normal direction, in Pa / m; C0 is the critical value for the transition from linear flow to radial flow, dimensionless; p is the pressure; s is the displacement along the streamline tangent direction; and n is the displacement along the streamline normal direction.

[0095] The radial flow region is:

[0096]

[0097] Specifically, the boundary of the convergence flow region caused by the sleeve orifice is given in step 4) below due to the special limitation of the annular region.

[0098] In step 2) above, the lower boundary 'a' of the linear flow region in the flow region is:

[0099]

[0100] in, This represents the minimum pressure value in the linear flow region, in Pa. The pressure is defined as the pressure whose ratio of the tangential pressure gradient to the normal pressure gradient along the streamline is less than the critical value for transformation.

[0101] The upper boundary b of the linear flow region in the flow region is:

[0102]

[0103] in, This represents the maximum pressure value in the linear flow region, expressed in Pa.

[0104] In step 3) above, if Figure 4 As shown, by observing the pressure contour map of the radial section of the sliding sleeve completion string, it can be seen that as the distance from the sliding sleeve to a point in the near-wellbore zone increases (i.e., the distance from the wellbore axis increases), the pressure contour lines in the near-wellbore zone tend to form a circle, and the fluid inside the circle flows radially with the sliding sleeve as the center. When the distance is large enough, the fluid outside the circle flows radially with the center of the wellbore as the center. Therefore, this step, based on geometric boundaries and roundness, determines the boundary of the radial flow region in the flow area, including:

[0105] 3.1) Determine the radial flow outer diameter r caused by the sliding sleeve. v :

[0106] r v =(1+v)r w (5)

[0107] Where, r w denoted as the radius of the slotted screen tube in meters (m), and v is the outer diameter correction parameter, which is dimensionless.

[0108] 3.2) As the pressure value of the pressure contour lines increases, the pressure contour lines tend to become more circular. To determine whether the pressure contour lines satisfy the condition of being the boundary between radial flow from the sleeve and radial flow away from the sleeve, the concept of roundness is introduced, and the roundness d is determined. r for:

[0109]

[0110] Where, r max r is the maximum radius of the radial flow region under the same pressure, in meters (m). min The minimum radius of the radial flow region under the same pressure, in meters; It is the average radius of the same pressure contour lines in the radial flow region.

[0111] 3.3) Numerical simulation of the inflow dynamics in the near-wellbore zone of the sliding sleeve completion string was performed. Data points of pressure contour lines in the near-wellbore zone were extracted, and the radii of all pressure contour lines were calculated. The average radius of the pressure contour lines was... We can take the average distance from multiple scattered points on the curve to the center of the circle, that is:

[0112]

[0113] Where, r i Let be the radius of the i-th point on the pressure isoline; n is the total number of points on the same pressure isoline.

[0114] 3.4) As can be seen from the definition: ... Figure 5 As shown, roundness refers to the degree to which a curve approximates a theoretical circle. When the difference between the maximum and minimum radii is zero, the roundness is 0. For pressure contour lines near the wellbore, as the pressure value increases, the average radius of points on the pressure contour lines gradually increases, and the pressure contour lines approach a theoretical circle, with the roundness approaching zero. As the average radius of points on the pressure contour lines increases, the roundness decreases, indicating that the pressure contour lines are closer to a theoretical circle. Let the roundness be d. r When the roundness is less than or equal to the critical roundness, the shape of the pressure contour lines can be considered close to the theoretical circle, and the fluid flow is radial, moving away from the sliding sleeve column; when the roundness d r When the roundness exceeds the critical value, the pressure contour lines can be considered as curves composed of circles centered on each slit unit of the slotted screen tube. The fluid flow is radial flow caused by the slit units. Therefore, the average radius of the circle corresponding to the critical roundness is the outer diameter of the radial flow caused by the slit unit. This allows us to determine the value of parameter v.

[0115] Specifically, the upper boundary c of the radial flow region in the flow region is... Its size is the average radius of the pressure contour lines corresponding to the critical roundness C1 condition, and the critical roundness C1 is:

[0116]

[0117] The lower boundary d of the radial flow region in the flow region is:

[0118]

[0119] Where D0 is the characteristic length of the orifice or slit that causes radial flow, in meters.

[0120] In step 4) above, regarding the definition of wellbore skin, any effect that causes the deviation between the actual bottom hole pressure and the theoretically calculated pressure in a well with a fixed production rate is called the skin effect. This additional skin pressure drop can be positive or negative, and the skin coefficient can also be positive or negative.

[0121]

[0122]

[0123] Where s is the epidermal coefficient, which is dimensionless; Δp s q represents skin pressure drop in MPa; q represents well production in cm³. 3 / s; μ is the fluid viscosity in mPa·s; K is the average reservoir permeability in D; L is the wellbore length in m; ξ0 is the actual flow channel start point; ξ1 is the actual flow channel end point; ξ′0 is the ideal flow channel start point; ξ′1 is the ideal flow channel end point; A(ξ) is the actual flow channel cross-sectional area in m². 2 A(ξ′) is the ideal flow channel cross-sectional area, in meters. 2 .

[0124] Therefore, in step 4) above, combining the relationship between the skin effect and the additional pressure drop, based on the defined flow area and the determined boundary, and according to the pressure drop difference between the reservoir fluid passing through the sliding sleeve completion string and the open hole, the skin coefficient caused by the sliding sleeve completion string in the near-wellbore zone is determined, including:

[0125] 4.1) As Figure 6 , Figure 7 As shown, based on the flow characteristics and defined boundaries of the linear flow region within the slit, the radial flow region caused by a single slit, the radial flow region caused by a slit unit, and the radial flow region far from the slit screen tube, the corresponding skin coefficients are established:

[0126] 4.1.1) Skin coefficient s of the linear flow region within the kerf sl .

[0127] The total open area of ​​the slotted screen tube is:

[0128] A = n s m s w s Lλ (12)

[0129] Where A is the total open area of ​​the slotted screen tube, in units of πrh; n s m is the number of slits within a slit unit, dimensionless. s The density of the circumferential kerf elements is dimensionless; w s λ is the slot width in meters; L is the length of the sliding sleeve completion string in meters; λ is the slot penetration ratio, and:

[0130]

[0131] w s =w Ds *r w (14)

[0132] Among them, l s l is the length of a single kerf. u w is the length of the slit unit. Ds r is the dimensionless width of the kerf element. w The radius of the slotted screen tube.

[0133] The dimensionless form of the total open area A of the slotted screen tube. D for:

[0134]

[0135] Among them, A O This represents the total area of ​​the outer wall of the slotted screen tube along its circumference.

[0136] Assuming the permeability inside the slotted screen tube is K, integrate the above formula (11):

[0137]

[0138]

[0139] The dimensionless form of formula (17) is:

[0140]

[0141] Among them, t Ds Let t be the dimensionless thickness of the slotted screen tube. Ds =t s / r w ; s(x) is the skin coefficient for the entire well section, dimensionless; s slξ is the skin coefficient of the linear flow region within the cut; D0 ξ is the dimensionless actual starting point of the flow channel; D1 The dimensionless actual flow channel endpoint; K(x,ξ) is the permeability in mD; A(x,ξ) is the actual flow channel cross-sectional area in m². 2 A(x,ξ′) is the ideal cross-sectional area of ​​the flow channel, in meters. 2 ; K represents the average reservoir permeability, expressed in mD. s Permeability within the cut, in mD; K D (x, ξ) represents dimensionless permeability in mD; A D (x,ξ) represents the dimensionless actual cross-sectional area of ​​the flow channel; K Ds The permeability within the cut is dimensionless and expressed in mD.

[0142] 4.1.2) Skin coefficient S of the radial flow region caused by a single slit sr .

[0143] Let r1 and r2 represent the inner and outer diameters of the radial flow element in the radial flow region caused by a single cut, respectively. Similar to the equivalent wellbore diameter of a fracture, the equivalent radius of the inner diameter r1 is w. s / 4, the equivalent radius of the outer diameter r2 is r u / n s r u Let r be the radius of the kerf element. u =w u / 2, w u The width of the kerf element is r2, which is w. u / 2n s The radial flow area is a function of the slit distance r.

[0144] The thickness h of the radial flow caused by a single slit is:

[0145]

[0146] Where h1 is the integral coefficient that varies with the kerf distance r, and is dimensionless; h2 is the initial integral length of a single kerf, in meters; l s The kerf length is in meters (m). u The length of the kerf unit is in meters (m).

[0147] Integrating along the radial direction over the flow region:

[0148]

[0149] in, This represents the number of slits along the axial direction.

[0150] Integrate the flow area part:

[0151]

[0152]

[0153] 4.1.3) Skin factor S of the radial flow region caused by the slotted element ur .

[0154] Use r2 and r3 to represent the inner diameter and outer diameter of the radial flow region caused by the slotted element around the wellbore respectively. Among them, the outer diameter of the radial flow in the radial flow region caused by a single slot is equal to the inner diameter of the radial flow region caused by the slotted element. Therefore, the inner diameter r2 of the radial flow region caused by the slotted element = r u , and the outer diameter r3 of the radial flow region caused by the slotted element = vr w , the flow region A ur is a function of the distance r from the slot:

[0155] A ur = m s (λL / l s )πrh (23)

[0156] The flow region A ur in dimensionless form A urD is:

[0157]

[0158] Among them, l Ds is the dimensionless slot length; r D is the dimensionless radius; h D is the dimensionless integral length.

[0159] The thickness h of the radial flow caused by the slotted element is the above formula (23).

[0160] If the slot on the slotted screen penetrates greatly, that is, γ < v, γ is the confluence coefficient in the wellbore axis direction, and γ = l u / 2r w , integrate the dimensionless flow region A urD :

[0161]

[0162]

[0163] If the slot on the slotted screen penetrates little, that is, γ > v, integrate the dimensionless flow region A urD :

[0164]

[0165]

[0166] 4.1.4) Skin factor S of the radial flow region far from the slotted screen ar .

[0167] The farther away from the slotted screen is the radial flow, the larger the radial flow area of the slotted screen. The inner diameter and outer diameter of the radial flow region far from the slotted screen are represented by r3 and r4 respectively. Among them, the inner diameter of the radial flow region far from the slotted screen is equal to the outer diameter of the radial flow region far from the slotted screen. Therefore, the inner diameter r3 of the radial flow region far from the slotted screen = (1 + v)r w , and the outer diameter of the radial flow region far from the slotted screen is r b , and the flow region A ar is a function of the distance r from the slot:

[0168] A = 2π(λL / l s )rh (28)

[0169] The flow region A ar in dimensionless form A arD is:

[0170] A arD = (λ / l Ds )r D h D (29)

[0171] Integrate the dimensionless flow region A arD :

[0172]

[0173] If the slot on the slotted screen penetrates greatly, that is, γ < v, then:

[0174]

[0175] Among them, S ar is the skin factor of the radial flow region far from the slotted screen.

[0176] If the slot on the slotted screen penetrates less, that is, γ > v, then:

[0177]

[0178] 4.2) Based on the flow characteristics and determined boundaries of the linear flow region and the converging flow region caused by the sliding sleeve holes in the determined flow region, establish the corresponding skin factor:

[0179] 4.2.1) Skin coefficient s of the linear flow region within the sleeve orifice Hl .

[0180] The orifice of the sliding sleeve is the region where the flow changes most drastically, exhibiting typical linear flow characteristics. The flow area of ​​the linear confluence is the total open area A of the sliding sleeve. Hl :

[0181] A Hl =m sH Lλw sH (33)

[0182] Among them, A H The total opening area of ​​the sliding sleeve is expressed in πrh (m). sH The density of the circumferential sliding sleeve is dimensionless; w sH This refers to the width of the sliding sleeve, in meters (m).

[0183] The skin coefficient s of the linear flow region within the sleeve orifice Hl for:

[0184]

[0185] Among them, t s K represents the thickness of the sliding sleeve column, in meters (m). H This represents the permeability within the orifice of the sliding sleeve.

[0186] 4.2.2) Skin coefficient S of the convergent flow zone caused by the orifice of the sliding sleeve Hr .

[0187] The sliding sleeve orifice is approximately square, and the reservoir fluid exhibits significant convergence phenomena when passing through the sliding sleeve orifice, including radial convergence flow and axial convergence flow.

[0188] The convergence flow area A caused by the orifice of the sliding sleeve Hr for:

[0189] A Hr =πrh Hr (35)

[0190] in:

[0191]

[0192] Among them, h Hr The radial flow thickness caused by the sleeve orifice, in meters (m); h H1r The dynamic boundary of the converging flow in the sliding sleeve varies with the kerf distance r, in meters; h H2 r is the axial spacing of the sleeve holes, in meters (m). c The upper boundary of the converging flow at the sleeve orifice, in meters (m); r oThe unit is meters (m) representing the lower boundary of the flow converging at the orifice of the sliding sleeve.

[0193] Skin coefficient S in the convergent flow area caused by the sliding sleeve orifice Hr for:

[0194]

[0195] Where ξ2 is the starting point of the integral of the sliding sleeve converging flow; ξ3 is the ending point of the integral of the sliding sleeve converging flow.

[0196] 4.3) Based on the skin coefficients of the linear flow region within the slot, the radial flow region caused by a single slot, the radial flow region caused by a slot unit, the radial flow region far from the slotted screen, the linear flow region within the sliding sleeve orifice, and the converging flow region caused by the sliding sleeve orifice, the skin coefficient S caused by the sliding sleeve completion string in the near-wellbore zone is obtained:

[0197] S = s sl +S sr +S ur +S ar +S Hr +S Hr (38)

[0198] The following detailed embodiments illustrate the method for calculating the flow skin of the sliding sleeve completion tubing string according to the present invention:

[0199] The slotted screen has a diameter of 0.18542 m, a wall thickness of 0.0127 m, a slot unit density of 4 slots / circle, a slot unit length of 0.3 m, 2 slots per unit, a permeability of 52500 mD in both the slots and the sliding sleeve perforations, a slot length of 0.28 m, a slot width of 0.006 m, a flow radius 50 m away from the slot, and a reservoir permeability of 500 mD. The sliding sleeve completion string has a length of 0.26 m, a radius of 0.067 m, and a wall thickness of 0.015 m. Figure 3 As shown, the dimensions of the sliding sleeve holes are as follows: Row 1: 6mm long, 12mm wide, with rounded chamfers at both ends and a diameter of 6mm; Row 2: 10mm long, 20mm wide, with rounded chamfers at both ends and a diameter of 10mm; Row 3: 20mm long, 20mm wide, with rounded chamfers at all four ends and a diameter of 10mm. During the production process, all three rows of sliding sleeve holes are fully open.

[0200] The specific calculation process is as follows:

[0201] 1) Based on the pressure distribution characteristics during the flow process of the sliding sleeve completion string, the flow zone of the reservoir fluid is divided.

[0202] 2) Determine the boundary of the linear flow region in the flow region based on the geometric boundary.

[0203] 3) Determine the boundary of the radial flow region in the flow region based on the geometric boundary and roundness.

[0204] 4) Based on the defined flow zones and boundaries, and according to the pressure drop difference between the reservoir fluid passing through the sliding sleeve completion string and the open hole, determine the skin coefficient caused by the sliding sleeve completion string in the near-wellbore zone:

[0205] A) Skin coefficient s of the linear flow region within the kerf sl .

[0206] The total open area of ​​the slotted screen tube is A = n s m s w s Lλ = 0.01165, and the cut penetration ratio λ = 0.9333. Therefore, the skin coefficient s of the linear flow region within the cut is... sl for:

[0207]

[0208] B) Skin coefficient S of the radial flow region caused by a single cut sr for:

[0209]

[0210] C) Skin coefficient S of the radial flow region caused by the slit element ur .

[0211] Calculations show that a flow coefficient γ = l will be generated along the shaft axis. u / 2r w =1.6179, the slit penetration on the slit screen tube is small, i.e., γ>v, therefore the skin coefficient S of the radial flow region caused by the slit element is small. ur for:

[0212]

[0213] D) Skin coefficient S in the radial flow region far from the slotted screen tube ar .

[0214] Since the penetration of the slits on the slotted screen tube is small, i.e., γ > v, then:

[0215]

[0216] E) Skin coefficient s of the linear flow region within the sleeve orifice Hl .

[0217] The total opening area A of the sliding sleeve Hl for:

[0218] A Hl =msH Lλw sH =0.002419

[0219] Therefore, the skin coefficient s of the linear flow region within the sleeve orifice Hl for:

[0220]

[0221] F) Skin coefficient S of the convergent flow zone caused by the sleeve orifice Hr for:

[0222]

[0223] The final total epidermal coefficient is:

[0224] S = s sl +S sr +S ur +S ar +S Hr +S Hr =7.368308

[0225] The skin thickness obtained by numerical simulation is 7.162151, and the relative error between the result and the theoretical calculation is 2.88%, indicating that the method of the present invention can effectively calculate the flow skin of the sliding sleeve completion string.

[0226] Example 2

[0227] This embodiment provides a sliding sleeve completion string flow skin calculation system, including:

[0228] The flow zone division module is used to divide the flow zone of reservoir fluid based on the pressure distribution characteristics during the flow process of the sliding sleeve completion string.

[0229] The linear flow region boundary determination module is used to determine the boundary of the linear flow region within the flow region based on the geometric boundary.

[0230] The radial flow region boundary determination module is used to determine the boundary of the radial flow region in the flow region based on the geometric boundary and roundness.

[0231] The skin coefficient determination module is used to determine the skin coefficient caused by the sliding sleeve completion string in the near-wellbore zone based on the defined flow area and the defined boundary, according to the pressure drop difference between the reservoir fluid passing through the sliding sleeve completion string and the open hole.

[0232] The system provided in this embodiment is used to execute the above-described method embodiments. For specific processes and details, please refer to the above embodiments, which will not be repeated here.

[0233] Example 3

[0234] This embodiment provides a processing device corresponding to the sliding sleeve completion string flow skin calculation method provided in Embodiment 1. The processing device can be applied to client processing devices, such as mobile phones, laptops, tablets, desktop computers, etc., to execute the method of Embodiment 1.

[0235] The processing device includes a processor, a memory, a communication interface, and a bus. The processor, memory, and communication interface are connected via the bus to enable communication between them. The memory stores computer programs that can run on the processing device. When the processing device runs the computer program, it executes the sliding sleeve completion string flow skin calculation method provided in Embodiment 1.

[0236] In some implementations, the memory may be high-speed random access memory (RAM), and may also include non-volatile memory, such as at least one disk storage device.

[0237] In other implementations, the processor can be any type of general-purpose processor, such as a central processing unit (CPU) or a digital signal processor (DSP), and there is no limitation here.

[0238] Furthermore, the logical instructions in the aforementioned memory can be implemented as software functional units and sold or used as independent products, and can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0239] Those skilled in the art will understand that the structure of the above-described computing device is only a partial structure related to the solution of this application and does not constitute a limitation on the computing device to which the solution of this application is applied. A specific computing device may include more or fewer components, or combine certain components, or have different component arrangements.

[0240] Example 4

[0241] This embodiment provides a computer program product corresponding to the sliding sleeve completion string flow skin calculation method provided in Embodiment 1. The computer program product may include a computer-readable storage medium on which computer-readable program instructions for executing the sliding sleeve completion string flow skin calculation method described in Embodiment 1 are loaded.

[0242] A computer-readable storage medium can be a tangible device that holds and stores instructions for use by an instruction execution device. A computer-readable storage medium can be, for example, but not limited to, an electrical storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any combination thereof.

[0243] The computer-readable storage medium provided in the above embodiments has a similar implementation principle and technical effect to the above method embodiments, and will not be described again here.

[0244] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0245] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0246] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0247] The above embodiments are only used to illustrate the present invention. The structure, connection method and manufacturing process of each component can be varied. All equivalent transformations and improvements made on the basis of the technical solution of the present invention should not be excluded from the protection scope of the present invention.

Claims

1. A method for calculating the flow skin of a sliding sleeve completion string, characterized in that, include: Based on the pressure distribution characteristics during the flow process of the sliding sleeve completion string, the flow zone of the reservoir fluid is divided. Based on geometric boundaries, determine the boundaries of linear flow regions within the flow region; Based on geometric boundaries and roundness, determine the boundary of the radial flow region in the flow region; Based on the defined flow zones and boundaries, the skin coefficient caused by the sliding sleeve completion string in the near-wellbore zone is determined according to the pressure drop difference between the reservoir fluid passing through the sliding sleeve completion string and the open hole. Based on the defined flow zones and boundaries, and according to the pressure drop difference between the reservoir fluid passing through the sliding sleeve completion string and the open hole, the skin coefficient induced by the sliding sleeve completion string in the near-wellbore zone is determined, including: Based on the flow characteristics and defined boundaries of the linear flow region within the slit, the radial flow region caused by a single slit, the radial flow region caused by a slit unit, and the radial flow region far from the slit screen tube in the defined flow region, the corresponding skin coefficient is established. Based on the linear flow region within the sleeve orifice in the defined flow region, the flow characteristics of the converging flow region caused by the sleeve orifice, and the defined boundary, the corresponding skin coefficient is established. Based on the skin coefficients of the linear flow region within the cut, the radial flow region caused by a single cut, the radial flow region caused by a cut unit, the radial flow region far from the cut screen, the linear flow region within the sliding sleeve orifice, and the convergence flow region caused by the sliding sleeve orifice, the skin coefficient of the sliding sleeve completion string in the near-wellbore zone is obtained. The skin coefficient of the linear flow region within the slit for: in, The dimensionless thickness of the slotted screen tube; This represents the number of slits within a slit unit. The density of the slit elements in the circumferential direction; The dimensionless width of the kerf element; The permeability within the dimensionless kerf; The cut penetration ratio; The skin coefficient of the radial flow region caused by the single slit for: in, This refers to the length of the sliding sleeve completion string; The length of the kerf unit; The kerf length; The width of the kerf; The skin coefficient of the radial flow region caused by the slit unit for: or in, A flow coefficient will be generated if the direction is along the shaft axis; The width of the kerf unit; This refers to the kerf distance; The thickness of the radial flow caused by the slit element; For parameters; The skin coefficient of the radial flow region away from the slotted screen tube for: or in, The radius of the slotted screen tube; The outer diameter is located away from the radial flow region of the slotted screen tube; The skin coefficient of the linear flow region within the sleeve orifice for: in, The thickness of the sliding sleeve column; The average permeability of the reservoir; The density of the circumferential sliding sleeve; The width of the sliding sleeve; The permeability of the sliding sleeve orifice; The skin coefficient of the convergence flow area caused by the sliding sleeve orifice for: in, The upper boundary of the flow converges at the orifice of the sliding sleeve; The flow converges at the lower boundary of the sleeve hole; The total open area of ​​the slotted screen tube; This refers to the axial spacing of the sleeve holes; The skin coefficient caused by the sliding sleeve completion string in the near-wellbore zone for: 。 2. The method for calculating the flow skin of a sliding sleeve completion string as described in claim 1, characterized in that, The flow regions of the reservoir fluid include the linear flow region within the sliding sleeve orifice, the linear flow region within the slit, the radial flow region caused by a single slit, the radial flow region caused by a slit unit, the radial flow region away from the slit screen tube, and the converging flow region caused by the sliding sleeve orifice.

3. The method for calculating the flow skin of a sliding sleeve completion string as described in claim 1, characterized in that, The linear flow region is: in, This represents the pressure gradient along the streamline direction; This represents the pressure gradient along the normal direction of the streamline; This is the critical value for the transition between linear flow and radial flow; For pressure; This represents the displacement along the streamline tangent direction. This represents the displacement in the direction of the streamline normal. The radial flow region is: 。 4. The method for calculating the flow skin of a sliding sleeve completion string as described in claim 3, characterized in that, The lower boundary of the linear flow region in the flow region for: in, This represents the minimum pressure value in the linear flow region. The pressure whose ratio of the tangential pressure gradient to the normal pressure gradient along the streamline is less than the critical value of transformation. Upper boundary of the linear flow region in the flow region for: in, This represents the maximum pressure value in the linear flow region.

5. The method for calculating the flow skin of a sliding sleeve completion string as described in claim 1, characterized in that, The upper boundary of the radial flow region in the flow region for: in, The average radius of the same pressure contour lines in the radial flow region; Lower boundary of radial flow region in flow region for: in, The characteristic length of the orifice or slit that causes radial flow.

6. A system for calculating the flow skin of a sliding sleeve completion string, characterized in that, include: The flow zone division module is used to divide the flow zone of reservoir fluid based on the pressure distribution characteristics during the flow process of the sliding sleeve completion string. The linear flow region boundary determination module is used to determine the boundary of the linear flow region within the flow region based on the geometric boundary. The radial flow region boundary determination module is used to determine the boundary of the radial flow region in the flow region based on the geometric boundary and roundness. The skin coefficient determination module is used to determine the skin coefficient caused by the sliding sleeve completion string in the near-wellbore zone based on the defined flow area and the defined boundary, according to the pressure drop difference between the reservoir fluid passing through the sliding sleeve completion string and the open hole. Based on the defined flow zones and boundaries, and according to the pressure drop difference between the reservoir fluid passing through the sliding sleeve completion string and the open hole, the skin coefficient induced by the sliding sleeve completion string in the near-wellbore zone is determined, including: Based on the flow characteristics and defined boundaries of the linear flow region within the slit, the radial flow region caused by a single slit, the radial flow region caused by a slit unit, and the radial flow region far from the slit screen tube in the defined flow region, the corresponding skin coefficient is established. Based on the linear flow region within the sleeve orifice in the defined flow region, the flow characteristics of the converging flow region caused by the sleeve orifice, and the defined boundary, the corresponding skin coefficient is established. Based on the skin coefficients of the linear flow region within the cut, the radial flow region caused by a single cut, the radial flow region caused by a cut unit, the radial flow region far from the cut screen, the linear flow region within the sliding sleeve orifice, and the convergence flow region caused by the sliding sleeve orifice, the skin coefficient of the sliding sleeve completion string in the near-wellbore zone is obtained. The skin coefficient of the linear flow region within the slit for: in, The dimensionless thickness of the slotted screen tube; This represents the number of slits within a slit unit. The density of the slit elements in the circumferential direction; The dimensionless width of the kerf element; The permeability within the dimensionless kerf; The cut penetration ratio; The skin coefficient of the radial flow region caused by the single slit for: in, This refers to the length of the sliding sleeve completion string; The length of the kerf unit; The kerf length; The width of the kerf; The skin coefficient of the radial flow region caused by the slit unit for: or in, A flow coefficient will be generated if the direction is along the shaft axis; The width of the kerf unit; This refers to the kerf distance; The thickness of the radial flow caused by the slit element; For parameters; The skin coefficient of the radial flow region away from the slotted screen tube for: or in, The radius of the slotted screen tube; The outer diameter is located away from the radial flow region of the slotted screen tube; The skin coefficient of the linear flow region within the sleeve orifice for: in, The thickness of the sliding sleeve column; The average permeability of the reservoir; The density of the circumferential sliding sleeve; The width of the sliding sleeve; The permeability of the sliding sleeve orifice; The skin coefficient of the convergence flow area caused by the sliding sleeve orifice for: in, The upper boundary of the flow converges at the orifice of the sliding sleeve; The flow converges at the lower boundary of the sleeve hole; The total open area of ​​the slotted screen tube; This refers to the axial spacing of the sleeve holes; The skin coefficient caused by the sliding sleeve completion string in the near-wellbore zone for: 。 7. A processing device, characterized in that, It includes computer program instructions, wherein when the computer program instructions are executed by the processing device, they are used to implement the steps corresponding to the method for calculating the flow skin of the sliding sleeve completion string as described in any one of claims 1-5.

8. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer program instructions, wherein when the computer program instructions are executed by a processor, they are used to implement the steps corresponding to the method for calculating the flow skin of the sliding sleeve completion string as described in any one of claims 1-5.

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