Superheated steam huff and puff-to-drive oil reservoir screening boundary determination method and system

Abstract

The invention discloses a superheated steam huff and puff-to-drive oil reservoir screening boundary determining method and system. The determining method comprises the steps that the economic limit oil production of a heavy oil reservoir in a research area under different oil price conditions is determined; based on heavy oil reservoir geology and fluid parameters in a research area, a combined well pattern digital-analog model is established; determining production parameters influencing the exploitation effect of the heavy oil reservoir; drawing a two-dimensional coordinate graph of different production parameters and the accumulated oil production, and analyzing an influence rule of each production parameter on the accumulated oil production; and on the basis of the two-dimensional coordinate graph, production parameter values corresponding to the economic limit oil production under different oil prices are marked in the graph, and the production parameter values are production parameter boundaries of superheated steam huff and puff transfer of all production parameters under the condition of different oil prices. Through the finance net present value theory and establishment of two combined well pattern digital-analog models conforming to the actual oil reservoir, the influence rule on the accumulated oil production under multi-parameter and multi-level combination is analyzed, and the superheated steam huff and puff-to-drive oil reservoir screening method conforming to the actual oil reservoir condition is established.

Description

Technical Field

[0001] The present invention belongs to the technical field of oil and gas field development, and in particular relates to a method and system for determining a screening limit of an oil reservoir using superheated steam huff-and-puff flooding. Background Art

[0002] Heavy oil accounts for a significant portion of oil and gas resources. Its high density and viscosity make cold production challenging. Continuous exploration of heavy oil steam injection methods, evolving from conventional steam to high-quality steam to superheated steam, has yielded promising results in heavy oil fields. However, after repeated cycles of steam injection, well production rapidly declines, water cuts continue to rise, and development effectiveness deteriorates. This is primarily due to the severe heterogeneity of heavy oil reservoirs, the formation of steam channeling in high-permeability zones after multiple steam injection cycles, and significant formation pressure drops and energy losses. To further enhance crude oil recovery, the promotion and application of superheated steam flooding as a successor to steam injection is urgent. Superheated steam is a special form of water. Like conventional steam injection, it is used as a heat carrier in heavy oil recovery. Due to the unique characteristics of superheated steam, its oil recovery mechanism shares similarities with conventional steam injection, while also possessing its own unique characteristics. The mechanism of superheated steam oil recovery is: (1) high temperature viscosity reduction; (2) steam distillation; (3) thermal expansion; (4) hydrothermal cracking; (5) plugging removal; and (6) emulsification flooding.

[0003] Economic efficiency is a fundamental metric for measuring project success. After heavy oil steam flooding, transitioning to steam flooding is not only constrained by reservoir conditions but also by economic efficiency. To determine the boundaries for selecting suitable reservoirs for steam flooding, various economic threshold indicators must be clearly defined. However, current methods for calculating these indicators often suffer from unclear parameters and inconclusive cost classification, resulting in limitations in practical applications. Therefore, there is an urgent need for a convenient, practical, and reliable method for determining reservoir screening boundaries for superheated steam flooding. Summary of the Invention

[0004] In response to the above problems, the present invention discloses a method for determining the screening limit of a superheated steam huff-and-puff flooding reservoir, comprising:

[0005] Determine the economic limit of oil production under different oil price conditions in the heavy oil reservoirs in the study area;

[0006] Based on the geological and fluid parameters of the heavy oil reservoirs in the study area, a combined well pattern numerical model was established;

[0007] Determine the production parameters that affect the recovery of heavy oil reservoirs;

[0008] Draw a two-dimensional coordinate graph of different production parameters and cumulative oil production, and analyze the influence of each production parameter on cumulative oil production;

[0009] Based on the two-dimensional coordinate graph, the production parameter values ​​corresponding to the economic limit oil production under different oil prices are marked on the graph, that is, the production parameter limits of each production parameter under superheated steam huff-and-puff flooding under different oil price conditions.

[0010] Furthermore, the specific steps for determining the economic limit oil recovery under different oil price conditions of the heavy oil reservoir in the study area are as follows:

[0011] Based on the financial net present value calculation formula, the cumulative financial present value is equal to 0 to determine the economic limit oil production under different oil price conditions of the heavy oil reservoir in the study area.

[0012] Furthermore, the combined well pattern includes a two-vertical-one-horizontal well combined well pattern and a two-horizontal-well combined well pattern.

[0013] Furthermore, the production parameters include reservoir parameters, fluid parameters and development parameters.

[0014] Furthermore, the reservoir parameters include net-to-gross ratio and permeability;

[0015] The net-to-gross ratio ranges from 0.04 to 1;

[0016] The permeability range is 14.03-5540 mD.

[0017] Furthermore, the fluid parameters include oil saturation and viscosity;

[0018] The oil saturation range is 2.5%-80%;

[0019] The viscosity range is 2000-15000 mPa·s.

[0020] Furthermore, the development parameters include superheat and pressure maintenance levels;

[0021] The superheat range is 0-70°C.

[0022] Furthermore, the specific steps of drawing a two-dimensional coordinate graph of different production parameters and cumulative oil production and analyzing the influence of each production parameter on the cumulative oil production are as follows:

[0023] Numerical simulation calculations were performed under different production parameter combinations, and relationship curves between different production parameters and cumulative oil production were drawn to analyze the influence of various production parameters on cumulative oil production.

[0024] The present invention also discloses a system for determining the screening limit of a superheated steam huff-and-puff flooding oil reservoir, comprising:

[0025] The economic limit oil production unit is used to determine the economic limit oil production of heavy oil reservoirs in the study area under different oil price conditions;

[0026] Model unit, used to establish a combined well pattern numerical model based on the geological and fluid parameters of the heavy oil reservoir in the study area;

[0027] Production parameter unit, used to determine the production parameters that affect the production effect of heavy oil reservoirs;

[0028] The analysis unit is used to draw a two-dimensional coordinate graph of different production parameters and cumulative oil production, and analyze the influence of each production parameter on the cumulative oil production;

[0029] The production parameter limit unit is used to mark the production parameter values ​​corresponding to the economic limit oil production under different oil price conditions on a two-dimensional coordinate graph, that is, the production parameter limits of each production parameter under superheated steam huff-and-puff drive conditions under different oil price conditions.

[0030] Furthermore, the economic limit oil production unit is specifically used to:

[0031] Based on the financial net present value calculation formula, the cumulative financial present value is equal to 0 to determine the economic limit oil production under different oil price conditions of the heavy oil reservoir in the study area.

[0032] Compared with the prior art, the embodiments of the present invention have at least the following advantages: the present invention uses the financial net present value theory and establishes two combined well network numerical simulation models that conform to actual oil reservoirs to analyze the influence of multi-parameter and multi-level combinations on cumulative oil production, and establishes a superheated steam huff-and-puff drive reservoir screening method that is easy to use and conforms to actual oil reservoir conditions, laying the foundation for maximizing the benefits of oil field projects.

[0033] Other features and advantages of the present invention will be described in the following description, and in part will become apparent from the description, or will be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0035] Figure 1 A schematic diagram of a digital model for the screening limit of a two-vertical-well and one-horizontal-well combination well pattern is shown according to an embodiment of the present invention;

[0036] Figure 2 The cumulative oil production under different net-to-gross ratio conditions of a two-vertical-well-one-horizontal-well combination well pattern according to an embodiment of the present invention is shown;

[0037] Figure 3 The cumulative oil production under different permeability conditions of a well pattern of two vertical wells and one horizontal well according to an embodiment of the present invention is shown;

[0038] Figure 4 The cumulative oil production under different oil saturation conditions of a two-vertical-one-horizontal well combination well pattern according to an embodiment of the present invention is shown;

[0039] Figure 5 The cumulative oil production under different viscosity conditions of a well pattern of two vertical wells and one horizontal well according to an embodiment of the present invention is shown;

[0040] Figure 6 The cumulative oil production of a two-vertical-one-horizontal well combination pattern under different superheat conditions according to an embodiment of the present invention is shown;

[0041] Figure 7 It shows the cumulative oil production of a two-vertical-one-horizontal well combination pattern under different pressure-maintaining level conditions according to an embodiment of the present invention;

[0042] Figure 8 A schematic diagram of a digital model of a two-horizontal well combination pattern flooding screening limit according to an embodiment of the present invention is shown;

[0043] Figure 9 The cumulative oil production under different net-to-gross ratio conditions of the two-horizontal well combination pattern according to an embodiment of the present invention is shown;

[0044] Figure 10 The cumulative oil production of the two horizontal well combination pattern under different permeability conditions according to an embodiment of the present invention is shown;

[0045] Figure 11 The cumulative oil production of a two-horizontal well combination pattern under different oil saturation conditions according to an embodiment of the present invention is shown;

[0046] Figure 12 The cumulative oil production of the two horizontal well combination pattern under different viscosity conditions according to an embodiment of the present invention is shown;

[0047] Figure 13 The cumulative oil production of the two horizontal well combination pattern under different superheat conditions according to an embodiment of the present invention is shown;

[0048] Figure 14 The figure shows the cumulative oil production of the two horizontal well combination pattern under different pressure maintenance level conditions according to an embodiment of the present invention. DETAILED DESCRIPTION

[0049] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0050] The present invention proposes a method for determining reservoir screening limits for superheated steam huff-and-puff flooding, comprising:

[0051] Determine the economic limit of oil production under different oil price conditions in the heavy oil reservoirs in the study area;

[0052] Based on the geological and fluid parameters of the heavy oil reservoirs in the study area, a combined well pattern numerical model was established; the numerical model was established using reservoir numerical simulation software (CMG software).

[0053] Determine the production parameters that affect the recovery of heavy oil reservoirs;

[0054] Draw a two-dimensional coordinate graph of different production parameters and cumulative oil production, and analyze the influence of each production parameter on cumulative oil production;

[0055] Based on the two-dimensional coordinate graph, the production parameter values ​​corresponding to the economic limit oil production under different oil prices are marked on the graph, that is, the production parameter limits of each production parameter under superheated steam huff-and-puff flooding under different oil price conditions.

[0056] Therefore, based on the principle of input-output balance and with reference to the cost classification and calculation in actual field operations, the present invention improves and perfects the original calculation method. Through the theory of financial net present value, the economic limit of cumulative oil production is established. Financial net present value is a dynamic evaluation indicator that reflects the profitability of a project during the calculation period. The financial net present value of a project refers to the sum of the present values ​​of the net cash flows of each year discounted to the starting point of construction (the beginning of the construction period) according to the benchmark rate of return or a set discount rate (when no benchmark rate of return is established). In other words, it is the difference between the present value of all project revenues and the present value of all expenditures.

[0057] The present invention is based on the financial net present value theory. It first calculates the economic limit oil production under different oil price conditions. By establishing two combined well network numerical simulation models, six key parameters in reservoir, fluid and development are analyzed. Five levels are selected for analysis for each factor. Numerical simulation calculations are performed under different parameter combinations to analyze the influence of each parameter on the cumulative oil production. The limit range of each parameter under different crude oil prices is obtained, which provides a theoretical basis for evaluating the applicability of superheated steam huff-and-puff flooding in heavy oil reservoirs.

[0058] In some embodiments, the specific steps of determining the economic limit oil recovery under different oil price conditions of the heavy oil reservoir in the study area are as follows:

[0059] Based on the financial net present value calculation formula, the cumulative financial present value is equal to 0 to determine the economic limit oil production under different oil price conditions of the heavy oil reservoir in the study area.

[0060] The financial net present value can be calculated from the net cash flow in the cash flow statement. Projects with a cumulative financial net present value of not less than 0 can be considered for conversion.

[0061] The formula for calculating financial net present value is as follows:

[0062]

[0063] Where FNPV: cumulative financial net present value, US dollars; i: calculation time, a, i = 1, 2, ..., y; y: production years, a; Q o : Total oil production, t; P o : crude oil price, USD / t; n: number of wells; C m : Annual operating cost per well, US dollars; Q si : Annual steam injection volume, t, based on the assumption that 14t of steam is generated per ton of crude oil burned, the price is the same as the output price; i c : Benchmark rate of return; W: Total investment, USD.

[0064] For example, based on the financial net present value calculation formula, the economic limit oil production under different oil prices is obtained, as shown in Table 1.

[0065] Table 1 Economic limit oil production at different oil prices

[0066] Oil price (US dollars per barrel) 30 40 50 60 <![CDATA[Economic oil production volume / 10,000 m 3 > 30.09 23.49 19.53 16.90

[0067] In some embodiments, the combined well pattern includes a two-vertical-one-horizontal well pattern and a two-horizontal well pattern. The two combined well patterns have identical geological parameters. Due to the different well types, the steam injection rate of the vertical wells is slightly smaller than the cyclic steam injection rate of the horizontal wells. Parameters such as steam quality and steam temperature are the same.

[0068] In some embodiments, the production parameters include reservoir parameters, fluid parameters, and development parameters.

[0069] In some embodiments, the reservoir parameters include net-to-gross ratio and permeability;

[0070] The net-to-gross ratio ranges from 0.04 to 1;

[0071] The permeability range is 14.03-5540 mD.

[0072] In some embodiments, the fluid parameters include oil saturation and viscosity;

[0073] The oil saturation range is 2.5%-80%;

[0074] The viscosity range is 2000-15000 mPa·s.

[0075] In some embodiments, the development parameters include superheat and pressure maintenance levels;

[0076] The superheat range is 0-70°C.

[0077] This paper mainly studies six reservoir, fluid and development parameters that have a significant impact on the mining effect, namely net-to-gross ratio, permeability, oil saturation, viscosity, superheat and pressure maintenance level. According to the actual scope of the block, five levels of each factor are selected for analysis.

[0078] In some embodiments, the specific steps of drawing a two-dimensional coordinate graph of different production parameters and cumulative oil production and analyzing the influence of each production parameter on the cumulative oil production are as follows:

[0079] Based on CMG software and using numerical simulation technology, numerical simulation calculations were performed under different production parameter combinations, and the relationship curves between different production parameters and cumulative oil production were drawn to analyze the influence of each production parameter on cumulative oil production.

[0080] Among them, the influence law refers to the change law of cumulative oil production as the production parameters change.

[0081] The present invention uses the financial net present value theory and establishes two combined well network numerical simulation models that conform to actual oil reservoirs. It analyzes the influence of multi-parameter and multi-level combinations on cumulative oil production, and establishes an easy-to-use superheated steam huff-and-puff flooding reservoir screening method that conforms to actual oil reservoir conditions, laying the foundation for maximizing the benefits of oilfield projects.

[0082] Based on the above-mentioned method for determining the screening limit of a superheated steam huff-and-puff flooding reservoir, the present invention further discloses a system for determining the screening limit of a superheated steam huff-and-puff flooding reservoir, comprising:

[0083] The economic limit oil production unit is used to determine the economic limit oil production of heavy oil reservoirs in the study area under different oil price conditions;

[0084] Model unit, used to establish a combined well pattern numerical model based on the geological and fluid parameters of the heavy oil reservoir in the study area;

[0085] Production parameter unit, used to determine the production parameters that affect the production effect of heavy oil reservoirs;

[0086] The analysis unit is used to draw a two-dimensional coordinate graph of different production parameters and cumulative oil production, and analyze the influence of each production parameter on the cumulative oil production;

[0087] The production parameter limit unit is used to mark the production parameter values ​​corresponding to the economic limit oil production under different oil price conditions on a two-dimensional coordinate graph, that is, the production parameter limits of each production parameter under superheated steam huff-and-puff drive conditions under different oil price conditions.

[0088] In some embodiments, the economic limit oil production unit is specifically used to:

[0089] Based on the financial net present value calculation formula, the cumulative financial present value is equal to 0 to determine the economic limit oil production under different oil price conditions of the heavy oil reservoir in the study area.

[0090] Example 1: Screening Limits for Transformation Flooding in a Well Pattern Combination of Two Vertical Wells and One Horizontal Well

[0091] According to the actual parameters of a heavy oil field in Kazakhstan (oilfield geology and fluid parameters), a numerical model of a well pattern with two vertical wells and one horizontal well was established (e.g. Figure 1 As shown, Figure 1 (a) is a 3D schematic diagram, Figure 1 (b) is a schematic diagram of the IJ plane. The numerical model has a grid size of 30×20×20, a grid step size of 15×15×0.85m, a permeability of 2400mD, a porosity of 0.31, a formation depth of 280m, a net-to-gross ratio of 0.85, a formation temperature of 13.1°C (the default superheat is 0), a formation pressure of 2360kPa, a crude oil viscosity of 3400mPa·s, an oil saturation of 0.75, a horizontal well length of 300m, and an effective reservoir thickness of 15m. The superheated steam huff-and-puff phase lasts 200 days per cycle, with 20 days of steam injection, 5 days of shut-down, and 175 days of production. The daily steam injection rate per well is 120m for vertical wells. 3 / d, horizontal well 240m 3 / d. Daily liquid production of production wells: vertical well 30m 3 / d, horizontal well 60m 3 / d. In the fifth cycle, the daily steam injection rate of the superheated steam flooding stage is 80m 3 / d, daily liquid production 60m 3 The above parameter values ​​are the default values ​​for simulations based on the actual parameters of heavy oil fields. In studying the influence of steam huff-and-puff flooding parameters on development results, a single-factor method was used to change only one parameter, while the rest of the parameters remained at their default values.

[0092] In the process of screening the steam flooding of oil reservoirs, we must first clarify the influence of various parameters on the development effect of steam flooding, and then quantitatively study the boundaries of various parameters suitable for steam flooding. This example mainly studies the net-to-gross ratio, permeability, oil saturation, viscosity, superheat, and pressure maintenance level, which are six reservoir, fluid and development parameters that have a more significant impact on the production effect. According to the actual scope of the block, 5 levels of each factor were selected for analysis (as shown in Table 2). Using numerical simulation technology, numerical simulation calculations were performed under different parameter combinations. By comparing the development effects under different parameters, the influence of various parameters was analyzed (as shown in Table 2). Figure 2-7 and quantitatively determine the screening limits of each parameter at different crude oil prices.

[0093] Table 2 Steam stimulation drive screening parameter values

[0094]

[0095]

[0096] like Figure 2 As shown, Figure 2 (a) Cumulative oil production of a two-vertical-one-horizontal well pattern with different net-to-gross ratios during steam stimulation; Figure 2 (b) Cumulative oil production under different net-to-gross ratios of the two vertical wells and one horizontal well combination well pattern during the full stage of steam stimulation and steam flooding.

[0097] Depend on Figure 2 (a) It can be seen that with the increase of net-to-gross ratio, the cumulative oil production increases approximately linearly. This is mainly because the increase of net-to-gross ratio increases the effective thickness of the oil layer, and the corresponding increase of the original oil flow involved in production, so the development effect becomes better.

[0098] According to the economic limit of oil production at different oil prices, Figure 2 In (b), the lower limit of the net-to-gross ratio screening corresponding to the oil price can be determined, as shown in Table 3.

[0099] Table 3 Net-to-gross ratio screening limits for different oil prices

[0100] Oil price (US dollars per barrel) 30 40 50 60 Net-to-gross ratio >0.71 >0.56 >0.43 >0.36

[0101] like Figure 3 As shown, Figure 3 (a) Cumulative oil production under different permeability conditions of the two vertical wells and one horizontal well combination well pattern during steam stimulation stage; Figure 3 (b) is the cumulative oil production of the two vertical wells and one horizontal well combination pattern under different permeability conditions during the full stage of steam stimulation and steam flooding. Figure 3As shown in (a), permeability has a significant impact on the development effect of heavy oil steam stimulation. As permeability increases, the fluidity of heated crude oil increases and the cumulative oil production increases.

[0102] like Figure 3 As shown in (b), according to the economic limit oil production at different oil prices, the corresponding permeability screening limits can be obtained in the figure, as shown in Table 4.

[0103] Table 4 Permeability screening limits at different oil prices

[0104] Oil price (US dollars per barrel) 30 40 50 60 Permeability / mD >1100 >400 — —

[0105] Among them, — represents that under the corresponding oil price, the multiple values ​​selected by the parameters can ensure that the cumulative oil production is higher than the economic limit oil production.

[0106] like Figure 4 As shown, Figure 4 (a) Cumulative oil production under different oil saturation conditions of the two vertical wells and one horizontal well combination well pattern during steam stimulation stage; Figure 4 (b) is the cumulative oil production of the two vertical wells and one horizontal well combination pattern under different oil saturation conditions during the full stage of steam stimulation and steam flooding. Figure 4 As shown in (a), oil saturation has a great influence on the effect of heavy oil steam stimulation development. As the oil saturation increases, the amount of crude oil that can be heated and flowed increases, so its cumulative oil production also increases. According to the economic limit oil production at different oil prices, Figure 4 The corresponding oil saturation screening limits can be obtained in (b), as shown in Table 5.

[0107] Table 5 Oil saturation screening limits at different oil prices

[0108] Oil price (US dollars per barrel) 30 40 50 60 Oil saturation >0.66 >0.56 >0.5 >0.45

[0109] like Figure 5 As shown, Figure 5 (a) Cumulative oil production under different viscosity conditions of the two vertical wells and one horizontal well combination pattern during steam stimulation stage; Figure 5 (b) is the cumulative oil production of the two vertical wells and one horizontal well combination pattern under different viscosity conditions during the full stage of steam stimulation and steam flooding. Figure 5 As shown in (a), under the same reservoir parameters and steam injection process parameters, the lower the viscosity, the stronger the crude oil flow ability and the greater the cumulative oil production.

[0110] like Figure 5 As shown in (b), according to the economic limit oil production at different oil prices, the corresponding viscosity upper limit can be determined, as shown in Table 6.

[0111] Table 6 Viscosity screening limits for different oil prices

[0112] Oil price (US dollars per barrel) 30 40 50 60 Viscosity / mPa·s <7800 <11800 <14600 —

[0113] like Figure 6 As shown, Figure 6 (a) Cumulative oil production of a two-vertical-one-horizontal well pattern under different superheat conditions during steam stimulation; Figure 6 (b) is the cumulative oil production of the two vertical wells and one horizontal well combination pattern under different superheat conditions in the full stage of steam stimulation and steam flooding. Figure 6 As shown in (a), increasing superheat can increase the cumulative oil production, but the increase in cumulative oil production is small.

[0114] According to the economic limit of oil production at different oil prices, Figure 6 The corresponding upper limit of superheat is determined in (b), as shown in Table 7.

[0115] Table 7 Superheat screening limits at different oil prices

[0116] Oil price (US dollars per barrel) 30 40 50 60 Superheat / ℃ >0 >0 >＝0 >＝0

[0117] like Figure 7 As shown, Figure 7 (a) Cumulative oil production of a two-vertical-one-horizontal well pattern under different pressure-maintaining horizontal conditions during steam stimulation; Figure 7 (b) is the cumulative oil production of the two vertical wells and one horizontal well combination pattern under different pressure keeping level conditions during the whole stage of steam stimulation and steam flooding. Figure 7 As shown in (a), during the steam stimulation stage, the higher the pressure maintenance level, the more sufficient the formation energy, and the higher the cumulative oil production. Figure 7 (b) shows that there is an optimal value for the pressure maintenance level in the steam stimulation and full steam stages. According to the economic limit oil production at different oil prices, the corresponding pressure maintenance level screening limit of the pressure level well can be determined, as shown in Table 8.

[0118] Table 8 Pressure maintenance level screening limits at different oil prices

[0119] Oil price (US dollars per barrel) 30 40 50 60 Keep the pressure level <58％ <90％ — —

[0120] Based on the above numerical simulation technology, a numerical simulation study was conducted on six key parameters: net-to-gross ratio, permeability, oil saturation, viscosity, superheat, and pressure maintenance level. The influence of each parameter on cumulative oil production was analyzed. Based on the economic limit oil production under different oil prices, the parameter screening boundaries for steam stimulation and flooding in the two-vertical well and one horizontal well combination well pattern at different crude oil prices were clarified (see Table 9).

[0121] Table 9 Pressure maintenance level screening limits at different oil prices

[0122]

[0123] Example 2: Screening Limits for Two Horizontal Well Combination Pattern Flooding

[0124] According to the actual parameters of a heavy oil field in Kazakhstan (oilfield geology and fluid parameters), a numerical model of a two-horizontal well combination pattern was established (e.g. Figure 8 As shown, Figure 8 (a) is a 3D schematic diagram, Figure 8 (b) is a schematic diagram of the IJ plane. The numerical model has a grid size of 30×20×20, a grid step size of 15×15×0.85m, a permeability of 2400mD, a porosity of 0.31, a formation depth of 280m, a net-to-gross ratio of 0.85, a formation temperature of 13.1°C, a formation pressure of 2360kPa, a crude oil viscosity of 3400mPa·s, an oil saturation of 0.75, a horizontal well length of 300m, and an effective reservoir thickness of 15m. The superheated steam stimulation phase is 200 days per cycle, with 20 days of steam injection, 5 days of well shut-in, and 175 days of production. The daily steam injection rate of the horizontal well is 240m 3 / d. Daily liquid production of production wells: horizontal wells 60m 3 / d. In the fifth cycle, the daily steam injection rate of the superheated steam flooding stage is 80m 3 / d, daily liquid production 60m 3 / d.

[0125] In the example of the two-horizontal well combination numerical simulation model, the parameter types and parameter values ​​are the same as those in Example 1 (see Table 2). Using numerical simulation technology, numerical simulation calculations are performed under different parameter combinations. By comparing the development effects under different parameters, the influence of each parameter is analyzed (such as Figure 9-14 ), and quantitatively determine the screening limits of various parameters for the two-horizontal well combination flooding pattern under different crude oil prices (see Table 16).

[0126] like Figure 9 As shown, Figure 9 (a) Cumulative oil production of the two horizontal wells combined pattern under different net-to-gross ratio conditions during steam stimulation stage; Figure 9 (b) is the cumulative oil production of the two-horizontal well combination pattern under different net-to-gross ratio conditions in the full stage of steam stimulation + steam flooding. Figure 9 As shown in (a), it can be seen from the figure that with the increase of net-to-gross ratio, the cumulative oil production increases approximately linearly. This is mainly because as the net-to-gross ratio increases, the effective thickness of the oil layer increases, and the corresponding original oil flow involved in production increases, so the development effect becomes better.

[0127] like Figure 9 As shown in (b), the economic limit of oil production at different oil prices can be Figure 9 The corresponding net-to-gross ratio screening limits are obtained in (b), as shown in Table 10.

[0128] Table 10 Screening limits of net-to-gross ratio at different oil prices

[0129] Oil price (US dollars per barrel) 30 40 50 60 Net-to-gross ratio >0.72 >0.55 >0.45 >0.42

[0130] like Figure 10 As shown, Figure 10 (a) Cumulative oil production of the two horizontal wells under different permeability conditions during the steam stimulation stage; Figure 10 (b) is the cumulative oil production of the two-horizontal well combination pattern under different permeability conditions in the full stage of steam stimulation + steam flooding. Figure 10 As shown in (a), permeability has a great influence on the effect of heavy oil steam stimulation and development. As permeability increases, the mobility of heated crude oil increases and the cumulative oil production increases. According to the economic limit oil production at different oil prices, Figure 10 The corresponding permeability screening limits can be obtained in (b), as shown in Table 11.

[0131] Table 11 Permeability screening limits at different oil prices

[0132] Oil price (US dollars per barrel) 30 40 50 60 Permeability / mD >1500 >400 — —

[0133] like Figure 11 As shown, Figure 11 (a) Cumulative oil production of the two horizontal wells under different oil saturation conditions during steam stimulation stage; Figure 11 (b) is the cumulative oil production of the two-horizontal well combination pattern under different oil saturation conditions during the full stage of steam stimulation + steam flooding. Figure 11 As shown in (a), oil saturation has a significant impact on the development effect of heavy oil steam stimulation. As the oil saturation increases, the amount of crude oil that can be heated and flowed increases, so the cumulative oil production also increases.

[0134] According to the economic limit of oil production at different oil prices, Figure 11 The corresponding oil saturation screening limits are obtained in (b), as shown in Table 12.

[0135] Table 12 Oil saturation screening limits at different oil prices

[0136] Oil price (US dollars per barrel) 30 40 50 60 Oil saturation >0.66 >0.56 >0.48 >0.44

[0137] like Figure 12 As shown, Figure 12 (a) Cumulative oil production of the two horizontal wells combined pattern under different viscosity conditions during steam stimulation stage; Figure 12 (b) is the cumulative oil production of the two horizontal wells combined pattern under different viscosity conditions in the full stage of steam stimulation + steam flooding. Figure 12 As shown in (a), under the same reservoir parameters and steam injection process parameters, the lower the viscosity, the stronger the flow ability of the crude oil and the greater its cumulative oil production.

[0138] According to the economic limit of oil production at different oil prices, Figure 12 The corresponding viscosity screening limits can be obtained in (b), as shown in Table 13.

[0139] Table 13 Viscosity screening limits for different oil prices

[0140] Oil price (US dollars per barrel) 30 40 50 60 Viscosity / mPa·s <9500 <13000 <14700 —

[0141] like Figure 13 As shown, Figure 13 (a) Cumulative oil production of the two horizontal wells combined pattern under different superheat conditions during steam stimulation stage; Figure 13 (b) is the cumulative oil production of the two-horizontal well combination pattern under different superheat conditions in the full stage of steam stimulation + steam flooding. Figure 13 As shown in (a), when superheat > 0, cumulative oil production significantly increases compared to when superheat = 0. Superheat can increase cumulative oil production, but the increase is limited. Therefore, the corresponding screening limit is superheat > 0, as shown in Table 14.

[0142] Table 14 Superheat screening limits at different oil prices

[0143] Oil price (US dollars per barrel) 30 40 50 60 Superheat / ℃ >0 >0 >＝0 >＝0

[0144] like Figure 14 As shown, Figure 14 (a) Cumulative oil production of the two horizontal wells combined pattern under different pressure keeping level conditions during steam stimulation stage; Figure 14 (b) is the cumulative oil production of the two horizontal wells combined pattern under different pressure keeping level conditions in the full stage of steam stimulation + steam flooding. Figure 14 As shown in (a), there is an optimal value for the pressure maintenance level. In the early stage, increasing the pressure maintenance level can significantly increase production, but if the pressure maintenance level continues to increase, the cumulative oil production will continue to decline. According to the economic limit oil production at different oil prices, Figure 14 The corresponding pressure maintenance level screening limits are obtained from (b), as shown in Table 15.

[0145] Table 15 Pressure maintenance level screening limits at different oil prices

[0146] Oil price (US dollars per barrel) 30 40 50 60 Keep the pressure level 33％-55％ 25％-97％ — —

[0147] Based on the above numerical simulation technology, a numerical simulation study was conducted on six key parameters: net-to-gross ratio, permeability, oil saturation, viscosity, superheat, and pressure maintenance level. The influence of each parameter on cumulative oil production was analyzed. Based on the economic limit oil production under different oil prices, the well pattern type was changed to a two-horizontal well combination well pattern. The parameter screening boundaries of the two-horizontal combination well pattern for steam stimulation and flooding under different crude oil prices were clarified (see Table 16).

[0148] Table 16 Screening limits for throughput conversion of two horizontal well combination patterns

[0149]

[0150] Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for determining the screening limit of a superheated steam flooding reservoir, characterized in that: include: Determine the economic limit of oil production under different oil price conditions in the heavy oil reservoirs in the study area; Based on the geological and fluid parameters of the heavy oil reservoirs in the study area, a combined well pattern numerical model was established; Determine the production parameters that affect the recovery of heavy oil reservoirs; Draw a two-dimensional coordinate graph of different production parameters and cumulative oil production, and analyze the influence of each production parameter on cumulative oil production; Based on the two-dimensional coordinate graph, the production parameter values ​​corresponding to the economic limit oil production under different oil prices are marked on the graph, that is, the production parameter limits of each production parameter under superheated steam huff-and-puff flooding under different oil price conditions.

2. The method for determining the screening limit of a superheated steam flooding reservoir according to claim 1, characterized in that: The specific steps for determining the economic limit oil recovery under different oil price conditions of the heavy oil reservoir in the study area are as follows: Based on the financial net present value calculation formula, the cumulative financial present value is equal to 0 to determine the economic limit oil production under different oil price conditions of the heavy oil reservoir in the study area.

3. The method for determining the screening limit of a superheated steam flooding reservoir according to claim 1, characterized in that: The combined well pattern includes a two-vertical-one-horizontal well combined well pattern and a two-horizontal-well combined well pattern.

4. The method for determining the screening limit of a superheated steam flooding reservoir according to claim 1, wherein: The production parameters include reservoir parameters, fluid parameters and development parameters.

5. The method for determining the screening limit of a superheated steam flooding reservoir according to claim 4, characterized in that: The reservoir parameters include net-to-gross ratio and permeability; The net-to-gross ratio ranges from 0.04 to 1; The permeability range is 14.03-5540 mD.

6. The method for determining the screening limit of a superheated steam flooding reservoir according to claim 4, characterized in that: The fluid parameters include oil saturation and viscosity; The oil saturation range is 2.5%-80%; The viscosity range is 2000-15000 mPa·s.

7. The method for determining the screening limit of a superheated steam flooding reservoir according to claim 4, characterized in that: Said development parameters include superheat and pressure maintenance levels; The superheat range is 0-70°C.

8. The method for determining the screening limit of a superheated steam flooding reservoir according to claim 1, characterized in that: The specific steps of drawing a two-dimensional coordinate graph of different production parameters and cumulative oil production and analyzing the influence of each production parameter on cumulative oil production are as follows: Numerical simulation calculations were performed under different production parameter combinations, and relationship curves between different production parameters and cumulative oil production were drawn to analyze the influence of various production parameters on cumulative oil production.

9. A system for determining the screening limit of a superheated steam flooding reservoir, characterized in that: include: The economic limit oil production unit is used to determine the economic limit oil production of heavy oil reservoirs in the study area under different oil price conditions; Model unit, used to establish a combined well pattern numerical model based on the geological and fluid parameters of the heavy oil reservoir in the study area; Production parameter unit, used to determine the production parameters that affect the production effect of heavy oil reservoirs; The analysis unit is used to draw a two-dimensional coordinate graph of different production parameters and cumulative oil production, and analyze the influence of each production parameter on the cumulative oil production; The production parameter limit unit is used to mark the production parameter values ​​corresponding to the economic limit oil production under different oil price conditions on a two-dimensional coordinate graph, that is, the production parameter limits of each production parameter under superheated steam huff-and-puff drive conditions under different oil price conditions.

10. The system for determining reservoir screening limits for superheated steam huff-and-puff flooding according to claim 9, characterized in that: The economic limit oil production unit is specifically used for: Based on the financial net present value calculation formula, the cumulative financial present value is equal to 0 to determine the economic limit oil production under different oil price conditions of the heavy oil reservoir in the study area.

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