A method for identifying and preventing sand-carrying production in heavy oil cold production wells.

Abstract

This invention belongs to the field of oil and gas extraction engineering technology, specifically involving a method for judging sand-carrying production in heavy oil cold production wells and integrating sand control and removal. It aims to solve the problem of not being able to clearly determine in the field whether a well is suitable for sand-carrying production, experiencing production failures, or having low production efficiency. The invention includes: drawing a comprehensive coordination chart (CSC) for sand-carrying production in heavy oil cold production wells in loose sandstone reservoirs; analyzing the position of the dynamic characteristic curve of sand carrying in the wellbore on the CSC chart and its intersection with curves and reference lines to determine the feasibility of heavy oil cold production and sand-carrying production in loose sandstone reservoirs; based on the intersection relationships, determining the reasonable production range and optimal production of coordinated heavy oil cold production wells in loose sandstone reservoirs, and providing corresponding sand control methods and screen types. This invention can fully leverage the advantages of the integrated sand control and removal production mode for heavy oil cold production wells, improving the sand control effect of heavy oil cold production.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas extraction engineering technology, and specifically relates to an integrated method for judging sand-carrying production and preventing and discharging sand from heavy oil cold production wells. Background Technology

[0002] Heavy oil and extra-heavy oil in loose sandstone reservoirs are widely distributed globally and in my country, holding significant positions in both reserves and production. Heavy oil reservoirs are generally shallowly buried with poor diagenesis and loose, cemented layers, leading to severe sand production during extraction. Cold extraction of heavy oil refers to the direct extraction of heavy oil without heating the reservoir, a relatively low-cost and simple oil production technology that aligns with the current trend of "energy conservation and carbon reduction." However, due to the high viscosity of heavy oil reservoirs under cold extraction conditions (compared to thermal extraction, which reduces viscosity and facilitates flow), the drag force of the fluid on formation sand grains is stronger under the same production conditions. Loose sandstone reservoirs are more prone to sand production under cold extraction conditions, requiring sand control measures. However, due to the poor fluidity of heavy oil, excessively high sand control precision can hinder the flow of heavy oil when sand control measures block fine sand produced from the formation, resulting in "sand blockage."

[0003] Therefore, for wells in heavy oil cold-production reservoirs where sand control is difficult, the current approach is to combine sand control and drainage. This involves a coordinated method of reservoir sand control, bottom-hole sand control, and wellbore sand carrying. The sand control medium blocks the coarser sand particles produced from the formation, while the finer sand particles are carried to the surface for treatment through the wellbore. (See appendix) Figure 1 This method can reduce sand production in the formation to a certain extent while maintaining the flow of sand control medium and normal well production. It is an effective method for controlling sand production in loose sandstone heavy oil cold production reservoirs. Specifically, the sand control and drainage combined working conditions and production process of loose sandstone heavy oil cold production wells involve three processes: reservoir sand production, bottom hole sand control, and wellbore sand carrying. The three processes need to be coordinated to ensure the stable production of the entire production system, and an integrated coordinated design of sand control, sand drainage, and sand carrying is required.

[0004] Currently, the integrated design of sand control, sand removal, and sand carrying in heavy oil cold production wells in loose sandstone reservoirs still faces the following key issues:

[0005] (1) Lack of feasibility evaluation method for coordinating sand production and sand control-drainage-carrying system in cold production sand wells of heavy oil in loose sandstone reservoirs: In cold production sand wells of heavy oil in loose sandstone reservoirs, the reservoir produces formation sand into the wellbore. The sand control system blocks part of the coarse sand produced and discharges finer sand particles. The wellbore fluid carries the finer sand particles to the wellhead and the surface. To achieve stable production of the sand production-sand control-drainage-carrying system, the reservoir production-bottom sand control-wellbore sand carrying system needs to be coordinated. However, there is currently a lack of systematic and standardized feasibility evaluation indicators and evaluation methods, which makes it impossible to clearly determine whether a well is suitable for sand production on site.

[0006] (2) Lack of a coordinated optimization design method for sand production and sand control-drainage-carrying system in cold-production sand wells of heavy oil in loose sandstone reservoirs: In cold-production sand wells of heavy oil in loose sandstone reservoirs, the working regime (production pressure differential, pressure and production rate) has a direct impact on the dynamics of sand production in the reservoir, the dynamics of sand control and discharge at the bottom of the well, and the dynamics of sand carrying in the wellbore. Excessive or insufficient production pressure differential will cause the three systems of reservoir production, bottom sand control and sand carrying in the wellbore to fail to meet the coordination conditions, resulting in production failure or low production efficiency. Coordinated optimization design of the sand control-drainage-carrying system is very important. However, at present, there is a lack of a coordinated optimization design method for sand production and sand control-drainage-carrying system in cold-production sand wells of heavy oil in loose sandstone reservoirs. This makes it difficult to achieve optimization design on site, restricts the efficient production of the system, and makes it difficult to give full play to the advantages of the integrated production mode of sand control, drainage and carrying in cold-production heavy oil wells. Summary of the Invention

[0007] To address the aforementioned problems in existing technologies, namely the lack of a feasibility evaluation method for coordinating sand control, sand removal, and sand carrying systems in heavy oil cold production wells in loose sandstone reservoirs, which makes it impossible to clearly determine whether a well is suitable for sand carrying production in the field, and the lack of a system coordination and optimization design method, resulting in the reservoir production, bottom hole sand control, and wellbore sand carrying systems failing to meet coordination conditions, leading to production failures or low production efficiency, this invention proposes a method for judging sand carrying production in heavy oil cold production wells and integrating sand control, sand removal, and sand carrying. This method includes the following steps:

[0008] Step 1: Obtain the heavy oil cold production parameters of the heavy oil cold production well with sand production in the loose sandstone reservoir, and draw the comprehensive coordination chart for sand production, i.e., the CSC chart, based on the heavy oil cold production parameters. The heavy oil cold production parameters include geological parameters, heavy oil physical property parameters, wellbore and lifting equipment parameters, and expected production parameters. The CSC chart includes the maximum allowable formation sand particle size that the lifting equipment can pass through as a reference line, the critical sand production rate of the reservoir, the sand production / sand carrying particle size, the minimum sand carrying particle size curve of the wellbore, and the formation sand production particle size curve.

[0009] Step 2: Plot the first curve on the CSC chart and analyze its position on the CSC chart, its intersection with other curves on the CSC chart, and the reference line. Based on the intersection, determine the feasibility of sand-carrying production in the heavy oil cold production sand-carrying well. The feasibility determination includes whether sand is produced, whether sand-carrying production is possible, and whether sand control measures are needed during sand-carrying production. The first curve is the dynamic characteristic curve of sand-carrying in the wellbore of the heavy oil cold production sand-carrying well.

[0010] Step 3: Based on the feasibility assessment results and the cross-relationship, determine the reasonable production range and optimal production of the heavy oil cold production sand well, the sand control method, screen type, and sand blocking accuracy of the screen corresponding to the production.

[0011] In some preferred embodiments, a comprehensive coordination chart for sand-carrying production, i.e., a CSC chart, is drawn using the following method:

[0012] The maximum permissible sand particle size that the lifting equipment can pass through is denoted as d. sc It serves as a reference line for the maximum permissible particle size of the lifting equipment;

[0013] A sand production prediction model is used to predict the critical production pressure differential ΔP of oil wells under cold production conditions. c , will the △P c With fluid collection index J l Multiplying these together, we obtain the critical sand production rate Q. c It serves as the horizontal axis of the CSC chart, with the sand output / carrying particle size as the vertical axis;

[0014] Based on the aforementioned △P c An empirical model for predicting sand particle size was used to predict the sand particle size d produced in formations under different yields. s0 Then, the sand grain size curve of the formation was plotted, denoted as d. s0 :

[0015] Based on the d s0 Obtain the critical value of the particle size carried by sand in the wellbore of a heavy oil cold production sand-carrying well, and plot the minimum sand-carrying particle size curve d in the wellbore based on the critical value. s1min .

[0016] In some preferred embodiments, the △P c The critical sand output Q c The calculation method is as follows:

[0017]

[0018]

[0019] Q c =ΔP c ·J l

[0020] In the formula, ΔP c S0 is the critical production pressure differential for sand production; μ is the cohesion of the reservoir rock; σ is the Poisson's ratio of the rock; ze β is the vertical stress at the outer boundary; β is the Biot constant; α is the failure angle; P r For formation static pressure; β o For the viscosity correction factor of cold-extracted heavy oil; μ l The viscosity of the formation crude oil; μ lc Characteristic viscosity; V CL V represents the reservoir clay content; CLc Characteristic clay content; Qc J is the critical output for sand production. l This is the liquid collection index.

[0021] In some preferred embodiments, the empirical model for predicting the output sand particle size is as follows:

[0022]

[0023] In the formula, d s0 The maximum particle size of sand produced from the formation; d smax The maximum grain size of the core sand in the formation; d smin α represents the minimum particle size of the core sand in the formation; ΔP represents the production pressure differential of the oil well; α and β are both empirical coefficients.

[0024] In some preferred embodiments, the first curve is plotted as follows:

[0025] Based on the wellbore temperature and pressure curves under different oil well production conditions, calculate the flow velocity and viscosity of the oil-water mixture at all well depths under a given oil well production condition;

[0026] Based on the flow rate, viscosity, and density of the oil-water mixture, calculate the equivalent viscosity velocity sand-carrying index distribution at different well depths;

[0027] U = μ f ·v f ·ρ f

[0028] In the formula, μ f The viscosity of an oil-water mixture; v f ρ represents the flow rate of the oil-water mixture. f Represents the density of an oil-water mixture;

[0029] Find the minimum value U based on the U values ​​at all locations. min Corresponding well depth h t ;

[0030] At the specified ht, the maximum sand-carrying particle size ds1max of the wellbore is calculated using the critical sand-carrying particle size model;

[0031]

[0032]

[0033] In the formula, Ql is the oil well production; Af is the cross-sectional area of ​​the wellbore; ds1max is the maximum sand-carrying particle size of the wellbore; g is the gravitational acceleration; ρs is the density of the sand particles; CD is the resistance coefficient; and ht is the characteristic depth of the wellbore where the sand-carrying capacity is weakest.

[0034] Calculate the maximum sand-carrying particle size in the wellbore under different oil well production conditions Ql, and plot the dynamic characteristic curve D of sand-carrying in the wellbore based on the maximum sand-carrying particle size of all wellbores.

[0035] In some preferred embodiments, the wellbore sand-carrying dynamic characteristic curve D is based on the wellbore minimum sand-carrying particle size curve d. s1min The types of classification based on the positional relationship of the shaded area C enclosed by the sand grain size curve ds0 of the strata include:

[0036] Above the enclosed shaded area C, it is denoted as D1;

[0037] Within the enclosed shaded area C, it is denoted as D2;

[0038] Below the enclosing shaded area C, it is denoted as D3.

[0039] In some preferred embodiments, the feasibility determination is as follows:

[0040] Obtain the formation yield Q and compare it with the preset critical sand production yield Qc;

[0041] If Q is less than Qc, it is determined that the formation does not produce sand and there is no need for sand-carrying production, which is recorded as the result R0;

[0042] If Q is greater than Qc, then determine the type of the actual oil well's sand-carrying dynamic characteristic curve. Further, based on the formation's production rate Q and the preset critical production value of the corresponding curve type, determine the feasibility of sand-carrying production and the necessity of sand control.

[0043] In some preferred embodiments, the feasibility of sand-carrying production and the necessity of sand control are determined as follows:

[0044] For all the curve scenarios, sand-carrying production is feasible and sand prevention is not required within the preset critical production values ​​Qc1, Qc2, and Qc3a of the corresponding curve types.

[0045] For all the curve scenarios mentioned above, when the output exceeds the preset critical output values ​​Qc1, Qc2, and Qc3a of the corresponding curve type, sand-carrying production is feasible but sand prevention is required.

[0046] For cases belonging to the D3 curve, if the critical production value Qc3b of the corresponding preset curve type is exceeded, sand-carrying production is not feasible.

[0047] In some preferred embodiments, the reasonable production range and optimal production rate coordinated with the heavy oil cold production sand well, the sand control method matching the production rate, the screen type, and the sand-blocking accuracy of the screen are determined by the following method:

[0048] Obtain the medium production rate Qp in the predicted production parameters, and compare it with the preset sand production critical rate Qc;

[0049] If Qp < Qc, the reasonable production rate is designed as Q = Q c , the oil well does not produce sand, and there is no need to carry sand and prevent sand in the formation where sand does not produce;

[0050] If Qp > Qc, then determine the type of the dynamic sand-carrying characteristic curve of the actual oil well bore, and further calculate the reasonable production rate according to the production rate Qp and the critical production rate value of the corresponding curve type preset; <G

[0051] The sand control method adopts independent screen sand control, and the independent screen includes slotted or wire-wound screens;

[0052] The design of the screen slot width is based on the sand control / sand discharge critical particle size ds, and is calculated as W f = d s / 0.8.

[0053] In some preferred embodiments, the reasonable production rate calculation method is as follows:

[0054] For the cases of the D1, D2, and D3 curves:

[0055] Qc < Qp < the preset critical production rate value Qc1 / Qc2 / Qc3a of the corresponding curve type, the reasonable production rate is Q = Qc1 / Qc2 / Qc3a, and there is no need for sand control;

[0056] Qp > the preset critical production rate value Qc1 / Qc2 / Qc3b of the corresponding curve type: the reasonable production rate is Q = max{Qp, critical production rate value × 1.25}, sand control is required, and the sand discharge particle size is determined;

[0057] For the cases of the D3 curve:

[0058] Qp > Qc3b: It does not belong to sand-carrying production, and conventional sand control design is required.

[0059] The beneficial effects of the present invention:

[0060] 1. The present invention proposes a sand-carrying comprehensive coordination chart including the maximum allowable passing formation sand particle size of the lifting equipment, the reservoir sand production particle size, the maximum sand-carrying particle size and the minimum sand-carrying particle size in the wellbore varying with the production rate. Based on the CSC chart, a method for judging the coordination feasibility of the sand control - sand discharge - sand-carrying system considering the reservoir sand production law, the bottom hole sand control and sand discharge configuration, and the wellbore sand-carrying capacity is proposed, which is used to demonstrate and judge whether the heavy oil cold production sand production well in the unconsolidated sandstone reservoir is suitable for sand-carrying production and support the decision-making of the sand production control strategy;

[0061] 2. This invention also proposes a coordinated optimization design method for sand-carrying production and sand prevention-discharge-carrying systems based on CSC charts. It realizes the integrated design of sand prevention, sand discharge, and sand carrying in heavy oil cold production wells from four aspects: formation fluid supply, sand production prediction, sand prevention optimization, and sand carrying critical conditions. With the well operating conditions (production rate and production pressure difference) and the sand-blocking accuracy of the sand prevention system (which determines the sand blocking and discharge capacity) as the optimization design objectives, it can easily and quickly design reasonable sand blocking accuracy and production rate. This method can give full play to the advantages of the integrated production mode of sand prevention, discharge, and carrying in heavy oil cold production wells, improve the sand production control effect of heavy oil cold production, and solve the bottleneck problem of lack of direct design means in current engineering sites.

[0062] 3. The feasibility assessment method for sand-carrying production in cold-production heavy oil wells in loose sandstone reservoirs proposed in this invention, along with the integrated method of prevention, drainage, and sand-carrying, is applicable to different geological, production, fluid, and sand-production conditions, covering a wide range of well conditions, and is suitable for vertical, directional, and horizontal wells. The method is systematic and highly operable, helping to fully utilize and exploit the advantages of cold-production technology for heavy oil, and promoting energy conservation and carbon reduction (compared to thermal production methods for heavy oil). Attached Figure Description

[0063] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0064] Figure 1 This is a flowchart of the steps of an integrated method for identifying and preventing sand-carrying production in heavy oil cold production wells according to the present invention.

[0065] Figure 2 This is a schematic diagram of the coordination of the sand prevention, sand discharge, and sand carrying production system of the present invention.

[0066] Figure 3 This invention provides the formation sand particle size curve and the minimum sand-carrying particle size curve for wellbore.

[0067] Figure 4 This is a diagram illustrating the variation of the maximum sand-carrying particle size in the wellbore, drawn according to the present invention.

[0068] Figure 5 This invention relates to a CSC diagram for the integrated coordination of sand-carrying production in cold-production sand wells of heavy oil in loose sandstone reservoirs.

[0069] Figure 6 This is a diagram illustrating the feasibility and boundary determination of sand-carrying production in heavy oil cold extraction sand wells under scenario D1 of this invention.

[0070] Figure 7 This is a diagram illustrating the feasibility and boundary determination of sand-carrying production in heavy oil cold extraction sand wells under scenario D2 of this invention.

[0071] Figure 8This is a diagram illustrating the feasibility and boundary determination of sand-carrying production in heavy oil cold recovery sand wells under scenario D3 of this invention. in, Figure 2 In the context of wellbore sand control, the components are: 1. Bottom-hole sand control screen; 2. Fluid in the well casing section; 3. Artificial lift equipment; 4. Fluid in the well tubing section; 5. Sand particles carried by the well fluid; 6. Fine sand particles from the formation; 7. Coarse sand particles from the formation; and 8. Reservoir sand particle size d. s0。 Detailed Implementation

[0072] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention. Furthermore, it should be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings.

[0073] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0074] To more clearly explain the integrated method for judging and preventing sand-carrying production in heavy oil cold production wells according to the present invention, the following is a detailed explanation. Figures 1 to 8 The steps in the embodiments of the present invention will be described in detail below.

[0075] To address the current lack of feasibility evaluation methods and system coordination optimization design methods for coordinating sand control, sand removal, and sand carrying systems in cold production wells for heavy oil in loose sandstone reservoirs, this paper presents publicly available... Figure 2 Based on the system structure, this invention proposes an integrated method for judging and preventing sand-carrying production in heavy oil cold production wells. (See [link to relevant documentation]). Figure 1 The method includes the following steps:

[0076] Step 1: Obtain the heavy oil cold production parameters of the heavy oil cold production well with sand carrying capacity in the loose sandstone reservoir, and based on the heavy oil cold production parameters, draw a comprehensive carrying-sand-coordinate (CSC) chart. The heavy oil cold production parameters include geological parameters, heavy oil physical property parameters, wellbore and lifting equipment parameters, and expected production parameters. The CSC chart includes the maximum allowable formation sand particle size that the lifting equipment can pass through as a reference line, the critical sand production rate of the reservoir, the sand production / carrying particle size, the minimum sand carrying particle size curve of the wellbore, and the formation sand production particle size curve.

[0077] In this embodiment, the method for drawing the comprehensive coordination chart for sand-carrying production, i.e., the CSC chart, is as follows:

[0078] The maximum permissible formation sand particle size that the lifting equipment can pass through is obtained, denoted as dsc. This serves as a reference line for the maximum permissible particle size of the lifting equipment and is directly provided by the equipment's performance parameters. The limiting condition A for sand-carrying production is: the maximum particle size d of the formation sand actually carried into the wellbore. s1 <d sc If a self-spraying production method is used, then d sc =+∞, which essentially means that the condition restriction is not considered;

[0079] A sand production prediction model is used to predict the critical production pressure differential ΔPc of oil wells under cold production conditions. This ΔPc is then compared with the fluid production index J. l Multiply by the product to obtain the critical sand output Qc, which is used as the horizontal axis of the CSC chart, and the sand output / carrying particle size is used as the vertical axis.

[0080]

[0081]

[0082] Q c =ΔP c ·J l

[0083] In the formula, ΔP c S0 is the critical production pressure differential for sand production; μ is the cohesion of the reservoir rock; σ is the Poisson's ratio of the rock; ze β is the vertical stress at the outer boundary; β is the Biot constant; α is the failure angle; P r For formation static pressure; β o For the viscosity correction factor of cold-extracted heavy oil; μ l The viscosity of the formation crude oil; μ lc Characteristic viscosity; V CL V represents the reservoir clay content; CLc Characteristic clay content; Q c J is the critical output for sand production. l The fluid collection index;

[0084] Based on the ΔP c An empirical model for predicting sand particle size was used to predict the sand particle size ds0 of the formation under different yields, and then the formation sand particle size curve was plotted, denoted as d. s0 ( Figure 3 Middle curve A):

[0085] The empirical model for predicting sand particle size:

[0086]

[0087] In the formula, d s0 The maximum particle size of sand produced from the formation; d smaxThe maximum grain size of the core sand in the formation; d smin ΔP is the minimum particle size of the core sand in the formation; ΔP is the production pressure differential of the oil well; α and β are empirical coefficients, with α = 0.45 and β = 0.85 preferred.

[0088] Based on the d s0 Obtain the critical value of the particle size carried by sand in the wellbore of a heavy oil cold production sand-carrying well, and plot the minimum sand-carrying particle size curve d in the wellbore based on the critical value. s1min ( Figure 3 (Middle curve B) ：

[0089] d s1min =α.d s0

[0090] In the formula, α = 0.3 - 0.5;

[0091] Figure 3 In the diagram, the shaded area C between curves A and B represents the sand-carrying particle size region of the wellbore.

[0092] The first curve is drawn as follows:

[0093] Based on the wellbore temperature and pressure curves under different oil well production conditions, calculate the flow velocity and viscosity of the oil-water mixture at all well depths under a given oil well production condition;

[0094] Based on the flow rate, viscosity, and density of the oil-water mixture, calculate the equivalent viscosity velocity sand-carrying index distribution at different well depths;

[0095] U = μ f ·v f ·ρ f

[0096] In the formula, μ f The viscosity of an oil-water mixture; v f ρ represents the flow rate of the oil-water mixture. f Represents the density of an oil-water mixture;

[0097] The equivalent viscosity velocity carrying capacity index characterizes different wellbore locations and depths under current production conditions (see [reference]). Figure 3 The relative sand-carrying capacity at a given location is as follows: the smaller the U value, the less likely the location is to carry sand, and vice versa.

[0098] Find the minimum value U based on the U values ​​at all locations. min Corresponding well depth h t ;

[0099] At the specified ht, the maximum sand-carrying particle size d in the wellbore is calculated using the critical sand-carrying particle size model. s1max ;

[0100]

[0101]

[0102] In the formula, Ql is the oil well production; Af is the cross-sectional area of ​​the wellbore; d s1max ρs is the maximum sand-carrying particle size in the wellbore; g is the gravitational acceleration; ρs is the density of the sand particles; CD is the drag coefficient; ht is the characteristic depth of the wellbore where the sand-carrying capacity is weakest.

[0103] Repeatedly calculate all production data points, calculate the maximum sand-carrying particle size in the wellbore under different oil well production Ql conditions, and plot the dynamic characteristic curve D of wellbore sand carrying based on the maximum sand-carrying particle size of all wellbores. (See attached diagram) Figure 4 ;

[0104] Will Figure 4 The dynamic characteristic curve D of the wellbore carrying sand is added to the appendix. Figure 3 In this process, all curves are plotted on the same graph with the same coordinate system, forming a feasibility evaluation and optimization design chart for sand-carrying production. Figure 4 Curves D1, D2, and D3 are attached. Figure 3 The three typical cases of the wellbore sand-carrying dynamic characteristic curve D can be used to conveniently evaluate the feasibility of sand-carrying production in heavy oil cold production wells and to coordinate and optimize the sand control-sand removal-sand-carrying system design. Specifically, the wellbore sand-carrying dynamic characteristic curve D is based on the curve d of the minimum sand-carrying particle size in the wellbore. s1min The types of classification based on the positional relationship of the shaded region C enclosed by the formation sand grain size curve ds0 include:

[0105] Above the enclosed shaded area C, it is denoted as D1;

[0106] Within the enclosed shaded area C, it is denoted as D2;

[0107] Below the enclosing shaded area C, it is denoted as D3;

[0108] Step 2: Plot the first curve on the CSC chart and analyze its position on the CSC chart, its intersection with other curves on the CSC chart, and the reference line. Based on the intersection, determine the feasibility of sand-carrying production in the heavy oil cold production sand-carrying well. The feasibility determination includes whether sand is produced, whether sand-carrying production is possible, and whether sand control measures are needed during sand-carrying production. The first curve is the dynamic characteristic curve of sand-carrying in the wellbore of the heavy oil cold production sand-carrying well.

[0109] In this embodiment, the feasibility determination is: obtaining the formation yield Q and comparing it with the preset critical sand production yield Qc;

[0110] If Q is less than Qc, then the formation is determined not to produce sand and there is no need for sand-carrying production; this is recorded as result R0 (corresponding to...). Figure 5 , Figure 6 , Figure 7 (R0);

[0111] If Q is greater than Qc, then determine the type of the actual oil well's sand-carrying dynamic characteristic curve, and further determine the feasibility of sand-carrying production and the necessity of sand control based on the formation's production Q and the preset critical production value of the corresponding curve type.

[0112] The feasibility of sand-carrying production and the necessity of sand control are determined as follows:

[0113] For all the curve scenarios, within the preset critical production values ​​Qc1, Qc2, and Qc3a of the corresponding curve types, sand-carrying production is feasible and requires no sand control, denoted as result R1 (corresponding to...). Figure 8 , Figure 6 , Figure 7 (R1);

[0114] For all the curve scenarios described above, when the output exceeds the preset critical production values ​​Qc1, Qc2, and Qc3a for the corresponding curve type, sand-carrying production is feasible but sand prevention is required, denoted as result R2 (corresponding to respectively). Figure 8 , Figure 6 , Figure 7 (R2);

[0115] For cases belonging to curve D3, when the preset critical production value Qc3b for the corresponding curve type is exceeded, sand-carrying production is not feasible, and this is recorded as result R3 (corresponding to...). Figure 8 (R3);

[0116] To facilitate clear and obvious understanding, the following descriptions will be provided in detail according to the specific circumstances:

[0117] (1) If it is curve D1 (see Figure 6 The feasibility of sand carrying and the necessity of sand prevention are determined according to the following methods:

[0118] a. If the output Q c The strata do not produce sand, so there is no need for sand-carrying production. Figure 6 The result is R0);

[0119] b. If Q c <Q c1 ​​Sand-carrying production is feasible and no bottom sand control measures are required (result R1 in the attached figure); the judgment criteria are: ① Under all production conditions that meet this condition, curve D1 is above curve A, indicating that the maximum particle size corresponding to the sand-carrying capacity of the wellbore is greater than the particle size of the sand produced from the formation; ② The particle size of the sand produced from the formation is lower than the maximum particle size allowed by the lifting equipment, which meets the lifting requirements; ③ No sand control measures are required because the particle size of the sand produced from all formations is lower than the sand-carrying capacity of the wellbore and can be carried to the surface without causing sand settling in the wellbore;

[0120] c. If Q c1 <Q, sand-carrying production is feasible, but sand prevention measures are required. Figure 6 The results are as follows: The criteria for judgment are: ① Under all production conditions, curve D1 is above curve A, indicating that the maximum particle size corresponding to the wellbore's sand-carrying capacity is greater than the particle size of the sand produced from the formation; ② The particle size of the sand produced from the formation exceeds the maximum allowable particle size of the lifting equipment, failing to meet the lifting requirements; sand control measures need to be taken to control the particle size of the produced sand within the maximum allowable particle size d of the lifting equipment. sc Within;

[0121] (2) If it is curve D2 (see Figure 7 The feasibility of sand carrying and the necessity of sand prevention are determined according to the following methods:

[0122] a. If the output Q c The strata do not produce sand, so there is no need for sand-carrying production. Figure 7 The result is R0);

[0123] b. If Q c <Q c2 Sand-carrying production is feasible and does not require bottom sand control measures. Figure 7 The results are as follows: R1); Judgment criteria: ① Under all production conditions that meet this condition, curve D2 is above curve A, indicating that the maximum particle size corresponding to the wellbore's sand-carrying capacity is greater than the particle size of the sand produced from the formation; ② The particle size of the sand produced from the formation is lower than the maximum particle size allowed by the lifting equipment, which meets the lifting requirements; ③ No sand control measures are required because the particle size of all sand produced from the formation is lower than the wellbore's sand-carrying capacity and can be carried to the surface without causing sand settling in the wellbore.

[0124] c. If Q c2 <Q, sand-carrying production is feasible, but sand prevention measures are required. Figure 7 ​​The results are as follows: (R2); Judgment criteria: ① Under all production conditions that meet this condition, curve D2 is above curve B, which meets the minimum sand-carrying particle size requirement of the project; ② The sand particles carried by the wellbore are lower than the maximum allowable particle size of the lifting equipment, which meets the lifting requirements; ③ Sand control measures need to be taken because the maximum particle size corresponding to the sand-carrying capacity of the wellbore is lower than the particle size of the sand produced by the formation. The wellbore cannot carry all the formation sand produced by the formation, so sand control measures need to be taken to control the particle size of the produced sand within the range of the sand-carrying particle size of the wellbore.

[0125] (3) If it is curve D3 (see Figure 8 The feasibility of sand carrying and the necessity of sand prevention are determined according to the following methods:

[0126] a. If the output Q c The strata do not produce sand, so there is no need for sand-carrying production. Figure 8 The result is R0);

[0127] b. If Q c <Q c3a Sand-carrying production is feasible and does not require bottom sand control measures. Figure 8 The results are as follows: R1); Judgment criteria: ① Under all production conditions that meet this condition, curve D3 is above curve A, indicating that the maximum particle size corresponding to the wellbore's sand-carrying capacity is greater than the particle size of the sand produced from the formation; ② The particle size of the sand produced from the formation is lower than the maximum particle size allowed by the lifting equipment, which meets the lifting requirements; ③ No sand control measures are required because the particle size of all sand produced from the formation is lower than the wellbore's sand-carrying capacity and can be carried to the surface without causing sand settling in the wellbore.

[0128] c. If Q c3a <Q c3b Sand-carrying production is feasible, but sand prevention measures are required. Figure 8 The results are as follows: (R2); Judgment criteria: ① Under all production conditions that meet this condition, curve D3 is above curve B, which meets the minimum sand-carrying particle size requirement of the project; ② The sand particles carried by the wellbore are lower than the maximum allowable particle size of the lifting equipment, which meets the lifting requirements; ③ Sand control measures need to be taken because the maximum particle size corresponding to the sand-carrying capacity of the wellbore is lower than the sand particle size produced by the formation. The wellbore cannot carry all the formation sand produced by the formation, so sand control measures need to be taken to control the sand particle size produced within the sand-carrying particle size range of the wellbore.

[0129] d. If Q c3b <Q, sand-carrying production is not feasible (even with sand control measures), sand control measures are required. Figure 7 The results are as follows: (R3); Judgment criteria: ① Under all production conditions that meet the requirements, curve D3 is below curve B, which does not meet the minimum sand-carrying particle size requirement of the project, and sand-carrying production loses its engineering value; ② The formation produces sand but cannot carry sand for production, and sand prevention measures are required. ​​​

[0130] The above judgment process is summarized in Table 1 as follows:

[0131] Table 1

[0132] Step 3: According to the feasibility discrimination result and in combination with the cross relationship, obtain the reasonable production range and the optimal production of the sand production well for heavy oil cold production, the sand control method, the screen type and the sand control precision of the screen that match the production;

[0133] In this embodiment, the method for obtaining the reasonable production range and the optimal production of the sand production well for heavy oil cold production, the sand control method, the screen type and the sand control precision of the screen that match the production is as follows:

[0134] Obtain the allocated production Qp in the predicted production parameters and compare it with the preset critical sand production Qc;

[0135] If Qp < Qc, the reasonable production is designed as Q = Q c , the oil well does not produce sand, and there is no need to carry sand and control sand for the formation without sand production;

[0136] If Qp > Qc, then judge the type of the dynamic sand-carrying characteristic curve of the actual oil well bore, and further calculate the reasonable allocated production according to the allocated production Qp and the critical production value of the corresponding curve type. For the cases belonging to the D1, D2, and D3 curve situations:

[0137] Qc < Qp < the preset critical production value Qc1 / Qc2 / Qc3a of the corresponding curve type, the reasonable production is designed as Q = Qc1 / Qc2 / Qc3a, and there is no need for sand control;

[0138] Qp > the preset critical production value Qc1 / Qc2 / Qc3b of the corresponding curve type: the production is designed as Q = max{Qp, critical production value × 1.25}, sand control is required, and the sand discharge particle size is determined;

[0139] For the cases belonging to the D3 curve situation:

[0140] Qp > Qc3b: It does not belong to sand-carrying production, and conventional sand control design is required;

[0141] The sand control method adopts independent screen sand control, and the independent screen includes slotted or wire-wound screens;

[0142] The screen slot width is designed based on the critical sand control / sand discharge particle size ds and calculated as Wf = ds / 0.8;

[0143] For the convenience of clear and obvious understanding, the following will be described separately according to different situations:

[0144] (1) If it is curve D1 (see appendix) Figure 6 ), calculated as follows:

[0145] a. If the production quantity Q is... p c The optimal output design is Q = Q c Oil wells do not produce sand, so there is no need to carry sand or prevent sand from entering the well.

[0146] b. If the production quantity Q p c1 The optimal output design is Q = Q c1 No sand control measures are required;

[0147] c. If the production quantity Q p Q c1 The output is calculated directly as follows:

[0148] Q = max{Q p Q c1 ×1.25}

[0149] Sand control measures are required, and the maximum allowable particle size for sand discharge, which is also the maximum permissible particle size for the lifting equipment, is d. sc The corresponding calculation method is shown in formula d. s1min =α.d s0 ;

[0150] d. If the production output is not specified, the designed output is Q = Q c1 No sand control measures are required;

[0151] (2) If it is curve D2 ( Figure 7 ), calculated as follows:

[0152] a. If the production quantity Q is... p c The optimal output design is Q = Q c Oil wells do not produce sand, so there is no need to carry sand or prevent sand from entering the well.

[0153] b. If the production quantity Q p c2 The optimal output design is Q = Q c2 No sand control measures are required;

[0154] c. If the production quantity Q p Q c2 The output is calculated directly as follows:

[0155] Q = max{Q p Q c2 ×1.25}

[0156] ​​​​Sand control measures are required, and the maximum required sand discharge particle size is the output Q within the specified range. Figure 7 The corresponding particle size value on curve D2 (marked as d) sc2 The corresponding design method is shown in formula d. s1min =α.d s0 ;

[0157] d. If the production output is not specified, the designed output is Q = Q c1 No sand control measures are required;

[0158] (3) If it is curve D3 ( Figure 8 ), calculated as follows:

[0159] a. If the production quantity Q is... p c The optimal output design is Q = Q c Oil wells do not produce sand, so there is no need to carry sand or prevent sand from entering the well.

[0160] b. If the production quantity Q c p c3a The optimal output design is Q = Q c3a No sand control measures are required;

[0161] c. If the production quantity Q c3b Q p Q c3a The output is calculated directly as follows:

[0162] Q = max{Q p Q c2 ×1.25}and Q c3b

[0163] Sand control measures are required, and the maximum required sand discharge particle size is the output Q within the specified range. Figure 7 The corresponding particle size value on curve D2 (marked as d) sc2 The corresponding design method is shown in formula d. s1min =α.d s0 ;

[0164] d. If the production quantity Q is... p Q c3b , directly take Q=Q p This does not fall under the category of sand-carrying production, and sand prevention measures are required. The sand-blocking particle size should be designed according to conventional sand prevention (this content is not within the scope of this invention and will not be elaborated further).

[0165] e. If the production output is not specified, the designed output is Q = Q c3a No sand control measures are required;

[0166] ​​​​In this embodiment, in order to achieve effective sand blocking and sand discharge, the sand prevention method is selected as independent screen pipe sand prevention, and the recommended screen pipe type is slotted screen pipe or wire-wound screen pipe.

[0167] For cases requiring a critical particle size ds for sand blocking / discharging, the design joint width is:

[0168] W f =d s / 0.8.

[0169] Although the steps in the above embodiments are described in the above order, those skilled in the art will understand that in order to achieve the effect of this embodiment, different steps do not need to be executed in such an order. They can be executed simultaneously (in parallel) or in a reverse order. These simple variations are all within the protection scope of this invention.

[0170] Those skilled in the art will recognize that the modules and method steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. The programs corresponding to the software modules and method steps can be placed in random access memory (RAM), main memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disks, removable disks, CD-ROMs, or any other form of storage medium known in the art. To clearly illustrate the interchangeability of electronic hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in electronic hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the invention.

[0171] The terms “first”, “second”, etc., are used to distinguish similar objects, not to describe or indicate a specific order or sequence.

[0172] The term "comprising" or any other similar term is intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus / device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent in such process, method, article, or apparatus / device.

[0173] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after such changes or substitutions will all fall within the scope of protection of the present invention.

Claims

1. A method for identifying and preventing sand-carrying production in heavy oil cold production wells, characterized in that, The method includes the following steps: Step 1: Obtain the heavy oil cold production parameters of the heavy oil cold production well with sand production in the loose sandstone reservoir, and draw the comprehensive coordination chart for sand production, i.e., the CSC chart, based on the heavy oil cold production parameters. The heavy oil cold production parameters include geological parameters, heavy oil physical property parameters, wellbore and lifting equipment parameters, and expected production parameters. The CSC chart includes the maximum allowable formation sand particle size that the lifting equipment can pass through as a reference line, the critical sand production rate of the reservoir, the sand production / sand carrying particle size, the minimum sand carrying particle size curve of the wellbore, and the formation sand production particle size curve. Step 2: Plot the first curve on the CSC chart and analyze its position on the CSC chart, its intersection with other curves on the CSC chart, and the reference line. Based on the intersection, determine the feasibility of sand-carrying production in the heavy oil cold production sand-carrying well. The feasibility determination includes whether sand is produced, whether sand-carrying production is possible, and whether sand control measures are needed during sand-carrying production. The first curve is the dynamic characteristic curve of sand-carrying in the wellbore of the heavy oil cold production sand-carrying well. Step 3: Based on the feasibility assessment results and the cross-relationship, determine the reasonable production range and optimal production of the heavy oil cold production sand well, the sand control method, screen type, and sand blocking accuracy of the screen corresponding to the production.

2. The method for identifying and preventing sand-carrying production in heavy oil cold production wells according to claim 1, characterized in that, The method for drawing the comprehensive coordination chart for sand-carrying production, i.e., the CSC chart, is as follows: The maximum permissible sand particle size that the lifting equipment can pass through is denoted as d. sc It serves as a reference line for the maximum permissible particle size of the lifting equipment; A sand production prediction model is used to predict the critical production pressure differential ΔP of oil wells under cold production conditions. c , will the △P c With fluid collection index J l Multiplying these together, we obtain the critical sand production rate Q. c The horizontal axis of the CSC chart is used as the horizontal axis, and the sand output / carrying particle size is used as the vertical axis. Based on the aforementioned △P c An empirical model for predicting sand particle size was used to predict the sand particle size d produced in formations under different yields. s0 Then, the sand grain size curve of the formation was plotted, denoted as d. s0 : Based on the d s0 Obtain the critical value of the particle size carried by sand in the wellbore of a heavy oil cold production sand-carrying well, and plot the minimum sand-carrying particle size curve d in the wellbore based on the critical value. s1min .

3. The integrated method for judging and preventing sand-carrying production in heavy oil cold production wells according to claim 2, characterized in that, The △P c The critical sand output Q c The calculation method is as follows: Q c =ΔP c ·J In the formula, ΔP c S0 is the critical production pressure differential for sand production; μ is the cohesion of the reservoir rock; σ is the Poisson's ratio of the rock; ze β is the vertical stress at the outer boundary; β is the Biot constant; α is the failure angle; P r For formation static pressure; β o For the viscosity correction factor of cold-extracted heavy oil; μ l The viscosity of the formation crude oil; μ lc Characteristic viscosity; V CL V represents the reservoir clay content; CLc Characteristic clay content; Q c J is the critical output for sand production. l This is the liquid collection index.

4. The integrated method for judging and preventing sand-carrying production in heavy oil cold production wells according to claim 2, characterized in that, The empirical model for predicting the output sand particle size is as follows: In the formula, d s0 The maximum particle size of sand produced from the formation; d smax The maximum grain size of the core sand in the formation; d smin α represents the minimum particle size of the core sand in the formation; ΔP represents the production pressure differential of the oil well; α and β are both empirical coefficients.

5. The integrated method for judging and preventing sand-carrying production in heavy oil cold production wells according to claim 2, characterized in that, The first curve is drawn as follows: Based on the wellbore temperature and pressure curves under different oil well production conditions, calculate the flow velocity and viscosity of the oil-water mixture at all well depths under a given oil well production condition; Based on the flow rate, viscosity, and density of the oil-water mixture, calculate the equivalent viscosity velocity sand-carrying index distribution at different well depths; U=μ f ·v f ·r f In the formula, μ f The viscosity of an oil-water mixture; v f ρ represents the flow rate of the oil-water mixture. f Represents the density of an oil-water mixture; Find the minimum value U based on the U values ​​at all locations. min Corresponding well depth h t ; At the specified ht, the maximum sand-carrying particle size ds1max of the wellbore is calculated using the critical sand-carrying particle size model; In the formula, Ql is the oil well production; Af is the cross-sectional area of ​​the wellbore; ds1max is the maximum sand-carrying particle size of the wellbore; g is the gravitational acceleration; ρs is the density of the sand particles; CD is the resistance coefficient; and ht is the characteristic depth of the wellbore where the sand-carrying capacity is weakest. Calculate the maximum sand-carrying particle size in the wellbore under different oil well production conditions Ql, and plot the dynamic characteristic curve D of sand-carrying in the wellbore based on the maximum sand-carrying particle size of all wellbores.

6. The integrated method for judging and preventing sand-carrying production in heavy oil cold production wells according to claim 5, characterized in that, The dynamic characteristic curve D of the wellbore sand carrying capacity is based on the curve d of the minimum sand carrying particle size of the wellbore. s1min The types of classification based on the positional relationship of the shaded area C enclosed by the sand grain size curve ds0 of the strata include: Above the enclosed shaded area C, it is denoted as D1; Within the enclosed shaded area C, it is denoted as D2; Below the enclosing shaded area C, it is denoted as D3.

7. The integrated method for judging and preventing sand-carrying production in heavy oil cold production wells according to claim 1, characterized in that, The feasibility determination is as follows: Obtain the formation yield Q and compare it with the preset critical sand production yield Qc; If Q is less than Qc, it is determined that the formation does not produce sand and there is no need for sand-carrying production, which is recorded as the result R0; If Q is greater than Qc, then determine the type of the actual oil well's sand-carrying dynamic characteristic curve. Further, based on the formation's production rate Q and the preset critical production value of the corresponding curve type, determine the feasibility of sand-carrying production and the necessity of sand control.

8. The integrated method for judging and preventing sand-carrying production in heavy oil cold production wells according to claim 7, characterized in that, The feasibility of sand-carrying production and the necessity of sand control are determined as follows: For all the curve cases, within the preset critical production volume values Qc1, Qc2, Qc3a corresponding to the respective curve types, sand-carrying production is feasible and sand control is not required. For all the curve cases, when exceeding the preset critical production volume values Qc1, Qc2, Qc3a corresponding to the respective curve types, sand-carrying production is feasible but sand control is required. For the D3 curve case, when exceeding the preset critical production volume value Qc3b corresponding to the curve type, sand-carrying production is not feasible.

9. The integrated method for judging and preventing sand-carrying production in heavy oil cold production wells according to claim 1, characterized in that, The reasonable production volume range, the optimal production volume, the sand control method, the screen type, and the sand retention accuracy of the screen matching the production volume for the heavy oil cold production sand-producing wells are obtained by the following method: Obtain the allocated production volume Qp in the predicted production parameters and compare it with the preset critical sand production volume Qc. If Qp < Qc, the reasonable production rate is designed as Q = Q c , the oil well does not produce sand, and there is no need to carry sand and prevent sand production in the formation; If Qp > Qc, determine the type of the sand-carrying dynamic characteristic curve of the actual oil well, and further calculate the reasonable allocated production volume according to the allocated production volume Qp and the preset critical production volume value corresponding to the curve type. The sand control method adopts independent screen sand control, and the independent screen includes a slotted or wire-wound screen. The screen tube slot width is designed based on the critical sand-blocking / sand-discharging particle size ds, and is calculated as W. f =d s / 0.

8.

10. The integrated method for judging and preventing sand-carrying production in heavy oil cold production wells according to claim 9, characterized in that, The method for calculating the reasonable production volume is as follows: For the D1, D2, D3 curve cases: Qc < Qp < the preset critical production volume value Qc1 / Qc2 / Qc3a corresponding to the curve type, the reasonable production volume is Q = Qc1 / Qc2 / Qc3a, and sand control is not required. Qp > the preset critical production volume value Qc1 / Qc2 / Qc3b corresponding to the curve type: The reasonable production volume is Q = max{Qp, critical production volume value × 1.25}, sand control is required, and the sand discharge particle size is determined. For the D3 curve case: Qp > Qc3b: It does not belong to sand-carrying production, and conventional sand control design is required.

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