A method for foam oil reservoir three-dimensional well pattern encryption and oil recovery

Abstract

This invention discloses a method for intensifying and extracting crude oil from foamy oil reservoirs using a three-dimensional well network. The method includes: determining extraction data for the foamy oil reservoir to be extracted; determining the enrichment area and reservoir type of the foamy oil reservoir based on the extraction data; determining the geological boundary level or seepage barrier configuration level of the enrichment area of ​​the foamy oil reservoir based on the extraction data and the reservoir type; setting up an intensified well network based on the geological boundary level and the seepage barrier configuration level; and extracting the foamy oil reservoir using the intensified well network. The extraction method provided by this invention classifies intra-layer residual oil, inter-layer residual oil, and seepage barrier-blocked residual oil according to the degree of influence of each parameter on different types of remaining reserves, constructing a three-dimensional intensified well network. This fully realizes the comprehensive utilization of remaining reserves in a three-dimensional manner, significantly improving the utilization rate of crude oil reserves and achieving orderly production succession.

Description

Technical Field

[0001] This invention relates to the field of oil extraction technology, and in particular to a method for densifying a three-dimensional well network in foam reservoirs and extracting crude oil. Background Technology

[0002] Foam oil refers to the phenomenon where dissolved gases naturally present in an oil reservoir. During natural depletion cold production, as the reservoir pressure decreases, these dissolved gases do not immediately detach from the crude oil but exist as dispersed bubbles within the crude oil and flow alongside it. In foam oil reservoirs, degassing is characterized by bubble point pressure and pseudo-bubble point pressure. Between these two points, dissolved gases are distributed within the crude oil, forming foam oil. This significantly reduces the crude oil's viscosity, increases its flowability, and extends the production time and yield of natural depletion cold production. Given the natural fluidity of the crude oil in foam oil reservoirs, horizontal well patterns are typically used for natural energy depletion development, with well spacing usually between 300 and 600 meters. However, as the formation pressure near the horizontal wells drops to the bubble point pressure, dissolved gases begin to detach from the crude oil in large quantities, causing a significant increase in viscosity and a rapid decline in production. Therefore, the recovery rate of foam oil natural energy depletion cold production is extremely low, typically estimated at 6%–12%. In summary, how to improve the reserve utilization rate and production of foam oil in the later stages of natural extraction through well network optimization is a technical problem that urgently needs to be solved. Summary of the Invention

[0003] This invention aims to at least partially solve one of the technical problems in the aforementioned technologies. Therefore, the objective of this invention is to propose a method for infilling and extracting crude oil from a three-dimensional well network in foam reservoirs. This method, based on existing conventional horizontal well networks, can conduct infill design targeting different types of remaining oil enrichment and characteristics, thereby achieving the goal of increasing reserve utilization and production, and ultimately improving oil recovery.

[0004] To achieve the above objectives, this invention proposes a method for densifying the three-dimensional well network in foam reservoirs and extracting crude oil, comprising:

[0005] Determine the extraction data for the foam oil reservoir to be exploited;

[0006] The enrichment area and reservoir type of the foam reservoir are determined based on the extraction data.

[0007] The geological boundary level or seepage barrier configuration level of the enrichment area of ​​the foam reservoir is determined based on the extraction data and the reservoir type.

[0008] A dense well network is set up according to the geological boundary level and the seepage barrier configuration level;

[0009] The foam reservoir is exploited based on the encrypted well network.

[0010] Preferably, the extraction data includes reservoir parameters, well layout parameters, and production parameters, wherein the reservoir parameters include continuous oil layer thickness, porosity, and remaining oil saturation; the well layout parameters include horizontal well spacing and horizontal well length; and the production parameters include near-wellbore formation pressure and oil production.

[0011] Preferably, the reservoir types of the foamed oil reservoir include inter-well residual oil, inter-layer residual oil, and residual oil blocked by intra-layer seepage barriers.

[0012] Preferably, determining the geological boundary grade or seepage barrier configuration grade of the enrichment area of ​​the foam reservoir based on the extraction data and the reservoir type includes:

[0013] When the reservoir type of the foamed oil reservoir is determined to be inter-well residual oil, the inter-well geological boundary index of the foamed oil reservoir is calculated based on the production data, and the inter-well geological boundary level of the enriched area is determined based on the inter-well geological boundary index.

[0014] When the reservoir type of the foam reservoir is determined to be interlayer residual oil, the interlayer geological boundary index of the foam reservoir is calculated based on the production data, and the interlayer geological boundary level of the enriched area is determined based on the interlayer geological boundary index.

[0015] When determining that the reservoir type of the foam reservoir is residual oil blocked by an intralayer seepage barrier, the seepage barrier configuration index of the foam reservoir is calculated based on the production data, and the seepage barrier configuration level of the enriched area is determined based on the seepage barrier configuration index.

[0016] Preferably, a dense well network is set according to the geological boundary level and the seepage barrier configuration level, including:

[0017] Several different levels of inter-well densification horizontal wells, several different levels of inter-layer densification horizontal wells, and several different levels of seepage barrier densification horizontal wells are pre-set;

[0018] Based on the inter-well geological boundary level of the enriched area, deploy corresponding level inter-well densification horizontal wells as target inter-well densification horizontal wells;

[0019] Based on the inter-layer geological boundary level of the enriched area, deploy corresponding level inter-layer infill horizontal wells as target inter-layer infill horizontal wells;

[0020] Deploy corresponding level of seepage barrier densification horizontal wells according to the seepage barrier configuration level of the enriched area, as target seepage barrier densification horizontal wells;

[0021] The target inter-well densified horizontal wells, the target inter-layer densified horizontal wells, and the target seepage barrier densified horizontal wells are combined to form the densified well network.

[0022] Preferably, when exploiting the foam reservoir according to the densified well network, the oil production of the foam reservoir is monitored.

[0023] Preferably, when the oil production of the foam reservoir is determined to be lower than a preset value, at least one of the inter-well infiltration horizontal wells, inter-layer infiltration horizontal wells, and seepage barrier infiltration horizontal wells constituting the infiltration well network is adjusted in level.

[0024] Preferably, any horizontal well in the densified well network is vertically located in the lower middle part of the oil layer to be exploited and the lower middle part of the oil layer to be exploited at the top of the seepage barrier. Any horizontal well in the densified well network is located in the horizontal well plane of the original horizontal well. The row spacing of the horizontal wells in the densified well network is the same as the row spacing of the original horizontal wells. The original horizontal wells are the horizontal wells in the oil layer before the exploitation of the foam reservoir.

[0025] Preferably, when exploiting the foam reservoir according to the densified well network, the densified well network is controlled to produce continuously, while the original horizontal wells are controlled to produce intermittently.

[0026] Preferably, when exploiting the foam reservoir according to the densified well network, the production pressure differential of the densified well network is controlled within a first preset range, and the production pressure differential of the original horizontal wells is controlled within a second preset range.

[0027] Preferably, the first preset range is 2 MPa to 4 MPa, and the second preset range is 1 MPa to 3 MPa.

[0028] Preferably, the exploitation of the foam reservoir based on the densified well pattern further includes:

[0029] The bottom-hole flowing pressure of the encrypted well network is obtained as the first bottom-hole flowing pressure;

[0030] The bottom-hole flowing pressure of the original horizontal well is obtained as the second bottom-hole flowing pressure;

[0031] Calculate the bottom hole pressure difference between the first bottom hole pressure and the second bottom hole pressure, and adjust the bottom hole pressure difference according to the operating time of the densified well network.

[0032] Compared with the prior art, the beneficial effects of the present invention are:

[0033] 1. Static parameters, well network parameters, and dynamic parameters are comprehensively considered in the decision-making and deployment of infill well networks. According to the degree of influence of each parameter on different types of remaining reserves, intervals are divided. Intra-layer remaining oil, inter-layer remaining oil, and remaining oil blocked by seepage barriers are classified by multiple factors. The classification geological boundaries for various types of remaining reserves to be developed by infill wells are clarified, which facilitates on-site site selection and layer selection.

[0034] 2. Following the order of utilization of remaining reserves within, between, and through seepage barriers, construct a three-dimensional infill well network consisting of infill horizontal wells within, interlayer infill horizontal wells, and infill horizontal wells through seepage barriers that cover the remaining oil-bearing layers. This will fully realize the comprehensive utilization of remaining reserves in a three-in-one manner, significantly improve the utilization rate of crude oil reserves, and achieve orderly succession of production.

[0035] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the written description and the accompanying drawings.

[0036] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0037] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof.

[0038] In the attached diagram:

[0039] Figure 1 This is a schematic diagram illustrating a method for densifying a three-dimensional well network and extracting crude oil in a foam reservoir, as provided in an embodiment of the present invention.

[0040] Figure 2 This is a schematic diagram of the first three-dimensional encrypted well network structure provided in an embodiment of the present invention;

[0041] Figure 3 This is a schematic diagram of the second three-dimensional encrypted well network structure given in an embodiment of the present invention.

[0042] Figure reference numerals: 0-1, First original horizontal well; 0-2, Second original horizontal well; 1, First inter-well reinforcement well; 2-1, First inter-layer reinforcement well; 2-2, Second inter-layer reinforcement well; 2-3, Third inter-layer reinforcement well; 3-1, Reinforcement well shielded by seepage barrier; 0-3, Third original horizontal well; 0-4, Fourth original horizontal well; 2, Second inter-well reinforcement well; 2-4, Fourth inter-layer reinforcement well; 2-5, Fifth inter-layer reinforcement well; 2-6, Sixth inter-layer reinforcement well. Detailed Implementation

[0043] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0044] like Figure 1 As shown, this invention provides a method for densifying and extracting crude oil from foam reservoirs using a three-dimensional well network, comprising:

[0045] Determine the extraction data for the foam oil reservoir to be exploited;

[0046] The enrichment area and reservoir type of the foam reservoir are determined based on the extraction data.

[0047] The geological boundary level or seepage barrier configuration level of the enrichment area of ​​the foam reservoir is determined based on the extraction data and the reservoir type.

[0048] A dense well network is set up according to the geological boundary level and the seepage barrier configuration level;

[0049] The foam reservoir is exploited based on the encrypted well network.

[0050] According to some embodiments of the present invention, determining the geological boundary level or seepage barrier configuration level of the enrichment area of ​​a foam reservoir based on extraction data and reservoir type includes:

[0051] (a) When the reservoir type of a foamy reservoir is determined to be inter-well residual oil:

[0052] Based on the extraction data, the inter-well geological boundary indices of the foam reservoir are calculated, including:

[0053] Substituting the continuous reservoir thickness h, porosity φ, remaining oil saturation So, and horizontal well spacing W of the foamed oil reservoir from the extraction data into the first static index calculation formula, the first static index X1 of the foamed oil reservoir is calculated, wherein the first static index calculation formula is:

[0054]

[0055] Substituting the daily oil production (Oil), horizontal well length (L), and near-formation pressure (Pr) of the foamed oil reservoir in the extraction data into the dynamic index calculation formula, the dynamic index Y1 of the foamed oil reservoir is calculated. The formula for calculating the dynamic index Y1 is as follows:

[0056]

[0057] Substituting the first static index and the dynamic index into the inter-well geological boundary index calculation formula, the inter-well geological boundary index Z1 of the foam reservoir is calculated, wherein the inter-well geological boundary index calculation formula is:

[0058] Z1 = X1 * X2;

[0059] The inter-well geological boundary index is compared with the preset value of the inter-well geological boundary index, and the inter-well geological boundary level of the enrichment area where the foam oil reservoir is located is determined based on the comparison result.

[0060] (b) When the reservoir type of a foamy oil reservoir is determined to be interlayer residual oil:

[0061] The interlayer geological boundary indices of the foamy oil reservoir are calculated based on the extraction data, including:

[0062] Substituting the continuous reservoir thickness h, porosity φ, and remaining oil saturation So of the foamed oil reservoir from the extraction data into the second static index calculation formula, the second static index X2 of the foamed oil reservoir is calculated. The second static index X2 is the inter-layer geological boundary index. The calculation formula for the second static index is as follows:

[0063]

[0064] The interlayer geological boundary index is compared with the preset value of the interlayer geological boundary index, and the interlayer geological boundary level of the enrichment area where the foam oil reservoir is located is determined based on the comparison result.

[0065] (c) When the reservoir type of a foamy reservoir is determined to be residual oil blocked by a seepage barrier:

[0066] The seepage barrier configuration level of the foam reservoir is calculated based on the extraction data, including:

[0067] Based on the seepage barrier area of ​​the foamed oil reservoir and the single-well control area of ​​the foamed oil reservoir in the mining data;

[0068] Calculate the area ratio of the seepage barrier area to the area controlled by the single well, and use the area ratio as the seepage barrier configuration index;

[0069] The seepage barrier configuration index is compared with the preset value of the seepage barrier configuration index, and the seepage barrier configuration level of the enrichment area where the foam reservoir is located is determined based on the comparison result.

[0070] In some embodiments of the present invention:

[0071] (a) The correspondence between the inter-well geological boundary grade and the inter-well geological boundary index (preset value) of the enrichment area of ​​foam reservoir for the remaining oil between wells is shown in the table below:

[0072] Inter-well primary geology Inter-well secondary geology Inter-well level three geology Preset values ​​of indicators ＞10 5-10 ＜10

[0073] For enriched areas with inter-well geological boundary index less than 10, it is not recommended to increase well density. For enriched areas with inter-well geological boundary index of 5-10, it is recommended to increase well density. For enriched areas with inter-well geological boundary index greater than 10, it is recommended to prioritize increasing well density.

[0074] (b) Regarding the remaining oil between layers, the correspondence between the interlayer geological boundary grade and the interlayer geological boundary index (preset value) of the enrichment area of ​​the foam reservoir is shown in the table below:

[0075] Interlayer Level 1 Geology Interlayer secondary geology Interlayer Level 3 Geology Preset values ​​of indicators ≥2 1-2 ≤1

[0076] For enriched areas with an interlayer geological boundary index of less than or equal to 1, it is not recommended to increase well density. For enriched areas with an interlayer geological boundary index of 1-2, it is recommended to increase well density. For enriched areas with an interlayer geological boundary index of greater than or equal to 2, it is recommended to prioritize increasing well density.

[0077] (c) The correspondence between the seepage barrier configuration level and the seepage barrier configuration index (preset value) of the enriched area of ​​foam reservoirs for residual oil in thick oil layers blocked by seepage barriers is shown in the table below:

[0078]

[0079] For enriched areas with a seepage barrier configuration index of less than or equal to 3, it is not recommended to increase the density of wells. For enriched areas with a seepage barrier configuration index of 3-5, it is recommended to increase the density of wells. For enriched areas with a seepage barrier configuration index of greater than or equal to 5, it is recommended to prioritize increasing the density of wells.

[0080] In an embodiment of the present invention, the foamy oil reservoir to be extracted is located prior to the present invention:

[0081] 1. The remaining dissolved gas-oil ratio in the oil reservoir is 6m. 3 / m 3 ;

[0082] 2. Remaining oil reserves between wells, between layers, and blocked by seepage barriers within the development zone. The remaining oil reserves between wells correspond to the main oil layer A with a thickness of 15 meters, an oil saturation of 70%, and a porosity of 32%. The remaining oil reserves between layers refer to a small layer B that has not yet been utilized, with a thickness of 10 meters, an oil saturation of 85%, and a porosity of 32%, in addition to the current main layer A. The remaining oil reserves blocked by seepage barriers correspond to an oil layer with a thickness of 12 meters above the seepage barrier, and a seepage barrier thickness of 2 meters. The blockage rate of the interlayer seepage barrier on the single-well controlled reserves is 50%, with an oil saturation of 85% and a porosity of 32%.

[0083] 3. Conventional horizontal wells are used for development, with a row spacing of 300 meters and a horizontal section length of 600 meters; currently, natural energy is used for development, with a daily oil production of 20 tons and the formation pressure dropping to 4 MPa.

[0084] Based on the method described above, the inter-well / inter-layer geological boundary indices and seepage barrier configuration indices of the foam reservoir to be exploited were calculated, as shown in the table below:

[0085]

[0086] Calculations show that the remaining reserves fall within the scope of priority deployment of a denser three-dimensional well network. Therefore, denser horizontal wells are deployed simultaneously between adjacent horizontal wells, in sub-layer B, and at the seepage barrier blocking location of the main layer A, forming the first denser well network. The horizontal wells are located in the existing horizontal well positions, with the same row spacing as the existing horizontal well network. Vertically, they are located in the lower middle part of the oil layer (1-2 meters from the bottom boundary of the oil layer) and in the lower middle part of the oil layer above the seepage barrier (1-2 meters from the bottom boundary of the seepage barrier). The deployment results of the first three-dimensional well network are as follows: Figure 2 As shown, Figure 2 In the diagram, 0-1 (first original horizontal well) and 0-2 (second original horizontal well) are the original horizontal wells in the foam reservoir before the development of the foam reservoir (i.e., the horizontal wells when the original reservoir was developed). 1, which is on the same plane as the original horizontal well, is the first inter-well reinforcement well between the original horizontal wells. 2-1, 2-2, and 2-3 are the first, second, and third inter-layer reinforcement wells, respectively. 3-1 is the reinforcement well blocked by the seepage barrier.

[0087] The infill wells adopt a continuous production operating system with production pressure differential controlled at MPa; the original well network adopts an intermittent production operating system with a dual control system of production pressure differential and bottom hole flowing pressure. The production pressure differential is controlled at 1 MPa, and the difference between the bottom hole flowing pressure and the infill well's bottom hole flowing pressure gradually decreases to 0, at a rate of 0.5 MPa per year.

[0088] Actual production data shows that through the deployment and development of a dense three-dimensional well network, the remaining reserves in the area have been effectively utilized, and the natural depletion production recovery rate has increased from 6% to 14% compared to before the network was developed.

[0089] According to another embodiment of the present invention, the parameters of the foam reservoir to be exploited are as follows:

[0090] 1. The remaining dissolved gas-oil ratio in the oil reservoir is 6m. 3 / m 3 ;

[0091] 2. Remaining oil reserves between wells, between layers, and blocked by seepage barriers within the development zone. The remaining oil between wells corresponds to the main oil layer C with a thickness of 17 meters, an oil saturation of 72%, and a porosity of 33%. The remaining oil between layers refers to a small layer D that has not yet been utilized, with a thickness of 12 meters, an oil saturation of 83%, and a porosity of 32%, in addition to the current main layer C. The remaining oil reserves blocked by seepage barriers correspond to an oil layer thickness of 5 meters above the seepage barrier, and the seepage barrier thickness is 0.8 meters. The blocking rate of the interlayer seepage barrier on the single-well controlled reserves is 30%, with an oil saturation of 85% and a porosity of 32%.

[0092] 3. Conventional horizontal well development is adopted, with a row spacing of 300 meters and a horizontal section length of 800 meters. Currently, natural energy is used for development, with a daily oil production of 20 tons and the formation pressure dropping to 4 MPa.

[0093] Using the same method, the inter-well / inter-layer geological boundary indices and seepage barrier configuration indices of the foam reservoir to be exploited were calculated, as shown in the table below:

[0094]

[0095] Calculations show that the remaining oil fraction blocked by the aforementioned seepage barrier is less than 3, falling into the category of areas where deployment is not feasible. The remaining reserves, however, fall into the category of areas where priority should be given to deploying a denser, multi-layered well network. Therefore, a second layer of denser horizontal wells is deployed simultaneously between adjacent horizontal wells and in layer D. The horizontal wells are positioned at the existing horizontal well locations, with the same spacing as the existing horizontal well network, and vertically located in the lower part of the oil layer (1-2 meters from the bottom boundary). The deployment result of the second layer of denser well network is as follows: Figure 3 As shown, Figure 3 In the diagram, 0-3 (the third original horizontal well) and 0-4 (the fourth original horizontal well) are the original horizontal wells in the foam reservoir before the development of the foam reservoir (i.e., the horizontal wells when the original reservoir was developed). 2, which is on the same plane as the third and fourth original horizontal wells, is the second inter-well infill well between the original horizontal wells. 2-4, 2-5, and 2-6 are the fourth, fifth, and sixth inter-layer infill wells, respectively.

[0096] The infill wells adopt a continuous production system with production pressure differential controlled at 3 MPa; the original well network adopts an intermittent production system with dual control of production pressure differential and bottom hole flowing pressure. The production pressure differential is controlled at 2 MPa, and the difference between the bottom hole flowing pressure and the infill well's bottom hole flowing pressure gradually decreases to 0 at a rate of 1 MPa per year.

[0097] Actual production data shows that through the deployment and development of a dense three-dimensional well network, the remaining reserves in the area have been effectively utilized, and the natural depletion production recovery rate has increased from 5% to 12% compared to before the network was developed.

[0098] In other embodiments of the present invention, when the inter-well geological boundary level, inter-layer geological boundary level, and seepage barrier configuration level of the enriched area of ​​the foam oil reservoir are all determined to be Level 1, priority is given to deploying Level 1 inter-well infill wells, Level 1 inter-layer infill horizontal wells, and Level 1 seepage barrier shielded infill horizontal wells to form a Level 1 three-dimensional infill well network. The horizontal well planes in the Level 1 three-dimensional infill well network are located at the positions of the horizontal well planes in the foam oil reservoir before exploitation, and the row spacing is the same as the existing horizontal well network. The horizontal wells in the Level 1 three-dimensional infill well network are vertically located in the lower middle part of the oil layer and the lower middle part of the oil layer at the top of the seepage barrier.

[0099] When exploiting foam reservoirs using a primary three-dimensional infill well network, the daily oil production of the foam reservoir is monitored. Once the daily oil production of the foam reservoir falls below 5 tons, primary inter-well infill wells, secondary inter-layer infill horizontal wells, and primary seepage barrier-shielded infill wells are deployed to form a secondary Class I three-dimensional infill well network. Simultaneously, Class I inter-well infill wells, primary inter-layer infill wells, and secondary seepage barrier-shielded infill wells are deployed to form a secondary Class II three-dimensional infill well network. The foam reservoir is then exploited based on both the secondary Class I and secondary Class II three-dimensional infill well networks. Similarly, the horizontal well planes in the secondary Class I and secondary Class II three-dimensional infill well networks are located at the positions of the horizontal well planes in the foam reservoir before exploitation, with the row spacing equal to the existing horizontal well network. The horizontal wells in the primary three-dimensional infill well network are vertically located in the lower middle part of the oil layer and the lower middle part of the oil layer above the seepage barrier.

[0100] When exploiting foamy oil reservoirs using Class I and Class II three-dimensional infill well networks, the daily oil production of the foamy oil reservoir is monitored. Once the daily oil production of the foamy oil reservoir falls below 5 tons, Class II inter-well infill wells, Class II inter-layer infill horizontal wells, and Class I seepage barrier infill wells are deployed to form a Class III two-dimensional infill well network. Simultaneously, Class II inter-well infill wells, Class I inter-layer infill horizontal wells, and Class II seepage barrier infill wells are deployed to form a Class IV two-dimensional infill well network. The foamy oil reservoir is then exploited using these Class III and Class IV infill well networks. The positions of the horizontal wells in these networks are the same as those in the aforementioned three-dimensional infill well networks.

[0101] When exploiting foamy oil reservoirs using Class II-III and Class II-IV three-dimensional infill well networks, the daily oil production of the foamy oil reservoir is monitored. Once the daily oil production of the foamy oil reservoir falls below 5 tons, a final Class II-V three-dimensional infill well network is deployed, consisting of inter-well infill wells, inter-layer horizontal infill wells, and infill wells shielded by seepage barriers, for the final exploitation of the foamy oil reservoir. During exploitation, the infill wells operate on a continuous production system, with the production pressure differential controlled at 2-4 MPa. Before exploiting the foamy oil reservoir, the original well network within the reservoir operates on an intermittent production system, employing a dual control system of production pressure differential and bottom hole flowing pressure. The production pressure differential is controlled at 1-3 MPa, and the difference between the bottom hole flowing pressure and the infill well's bottom hole flowing pressure gradually decreases to 0, at a rate of 0.5-2 MPa per year.

[0102] Compared to existing technologies, the advantages of the above technology are as follows: Firstly, it comprehensively considers static parameters, well network parameters, and dynamic parameters in the decision-making and deployment of infill well networks. Based on the degree of influence of each parameter on different types of remaining reserves, intervals are divided, and multi-factor classifications are applied to residual oil within layers, between layers, and under the influence of seepage barriers. This clarifies the geological boundaries for developing various types of remaining reserves using infill wells, facilitating on-site site selection and layer selection. Simultaneously, following the order of utilization of residual reserves within layers, between layers, and under seepage barriers, a three-dimensional infill well network is constructed, comprising infill wells within layers, interlayer infill wells, and horizontal wells for utilizing residual reserves under seepage barriers. This fully realizes the integrated utilization of remaining reserves, significantly improving the utilization rate of crude oil reserves and achieving orderly production succession.

[0103] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for densifying the three-dimensional well network and extracting crude oil in foam reservoirs, characterized in that, include: Determine the extraction data for the foam oil reservoir to be exploited; The enrichment area and reservoir type of the foam reservoir are determined based on the extraction data. The geological boundary level or seepage barrier configuration level of the enrichment area of ​​the foam reservoir is determined based on the extraction data and the reservoir type. A dense well network is set up according to the geological boundary level and the seepage barrier configuration level; The foam reservoir is exploited according to the aforementioned encrypted well pattern; The reservoir types of the foamed oil reservoirs include inter-well residual oil, inter-layer residual oil, and residual oil blocked by intra-layer seepage barriers; Based on the extraction data and the reservoir type, determine the geological boundary level or seepage barrier configuration level of the enrichment area of ​​the foam reservoir, including: When the reservoir type of the foamed oil reservoir is determined to be inter-well residual oil, the inter-well geological boundary index of the foamed oil reservoir is calculated based on the production data, and the inter-well geological boundary level of the enriched area is determined based on the inter-well geological boundary index. When the reservoir type of the foam reservoir is determined to be interlayer residual oil, the interlayer geological boundary index of the foam reservoir is calculated based on the production data, and the interlayer geological boundary level of the enriched area is determined based on the interlayer geological boundary index. When determining that the reservoir type of the foam reservoir is residual oil blocked by the intralayer seepage barrier, the seepage barrier configuration index of the foam reservoir is calculated based on the production data, and the seepage barrier configuration level of the enrichment area is determined based on the seepage barrier configuration index. Based on the extraction data, the inter-well geological boundary indices of the foam reservoir are calculated, including: Substituting the continuous reservoir thickness h, porosity φ, remaining oil saturation So, and horizontal well spacing W of the foamed oil reservoir from the extraction data into the first static index calculation formula, the first static index X1 of the foamed oil reservoir is calculated, wherein the first static index calculation formula is: X1=h f So W; Substituting the daily oil production (Oil), horizontal well length (L), and near-formation pressure (Pr) of the foamed oil reservoir in the extraction data into the dynamic index calculation formula, the dynamic index Y1 of the foamed oil reservoir is calculated. The formula for calculating the dynamic index Y1 is as follows: Y1=Oil / (Pr L); Substituting the first static index and the dynamic index into the inter-well geological boundary index calculation formula, the inter-well geological boundary index Z1 of the foam reservoir is calculated, wherein the inter-well geological boundary index calculation formula is: Z1=X1 X2; The calculation of the interlayer geological boundary index of the foamed oil reservoir based on the extraction data includes: substituting the continuous reservoir thickness h, porosity φ, and remaining oil saturation So of the foamed oil reservoir in the extraction data into the second static index calculation formula to calculate the second static index X2 of the foamed oil reservoir. The second static index X2 is the interlayer geological boundary index, wherein the calculation formula for the second static index is: X2=h φ So; Calculate the seepage barrier configuration index of the foamed oil reservoir based on the extraction data, including: the seepage barrier area of ​​the foamed oil reservoir and the single-well control area of ​​the foamed oil reservoir in the extraction data; Calculate the area ratio of the seepage barrier area to the area controlled by the single well, and use the area ratio as the seepage barrier configuration index.

2. The method for densifying the three-dimensional well network and extracting crude oil in foam reservoirs as described in claim 1, characterized in that, A dense well network is established based on the geological boundary level and the seepage barrier configuration level, including: Several different levels of inter-well densification horizontal wells, several different levels of inter-layer densification horizontal wells, and several different levels of seepage barrier densification horizontal wells are pre-set; Based on the inter-well geological boundary level of the enriched area, deploy corresponding level inter-well densification horizontal wells as target inter-well densification horizontal wells; Based on the inter-layer geological boundary level of the enriched area, deploy inter-layer infill horizontal wells of corresponding levels as target inter-layer infill horizontal wells; Deploy corresponding level seepage barrier densification horizontal wells according to the seepage barrier configuration level of the enriched area, as target seepage barrier densification horizontal wells; The target inter-well densified horizontal wells, the target inter-layer densified horizontal wells, and the target seepage barrier densified horizontal wells are combined to form the densified well network.

3. The method for densifying the three-dimensional well network and extracting crude oil in foam reservoirs as described in claim 2, characterized in that, When exploiting the foamed oil reservoir according to the encrypted well network, the oil production of the foamed oil reservoir is monitored.

4. The method for densifying the three-dimensional well network and extracting crude oil in foam reservoirs as described in claim 3, characterized in that, When the oil production of the foam reservoir is determined to be lower than a preset value, at least one of the inter-well infiltration horizontal wells, inter-layer infiltration horizontal wells, and seepage barrier infiltration horizontal wells constituting the infiltration well network is adjusted in level.

5. The method for densifying the three-dimensional well network and extracting crude oil in foam reservoirs as described in claim 2, characterized in that, Any horizontal well in the densified well network is vertically located in the lower middle part of the oil layer to be exploited and the lower middle part of the oil layer to be exploited at the top of the seepage barrier. Any horizontal well in the densified well network is located in the horizontal well plane of the original horizontal well. The row spacing of the horizontal wells in the densified well network is the same as the row spacing of the original horizontal wells. The original horizontal wells are the horizontal wells in the oil layer before the exploitation of the foam oil reservoir.

6. The method for densifying the three-dimensional well network and extracting crude oil in foam reservoirs as described in claim 5, characterized in that, When exploiting the foam reservoir according to the densified well network, the densified well network is controlled to produce continuously, while the original horizontal wells are controlled to produce intermittently.

7. The method for densifying the three-dimensional well network and extracting crude oil in foam reservoirs as described in claim 5, characterized in that, When exploiting the foam reservoir according to the densified well network, the production pressure differential of the densified well network is controlled within a first preset range, and the production pressure differential of the original horizontal wells is controlled within a second preset range.

8. The method for densifying the three-dimensional well network and extracting crude oil in foam reservoirs as described in claim 7, characterized in that, The first preset range is 2 MPa to 4 MPa, and the second preset range is 1 MPa to 3 MPa.

9. The method for densifying the three-dimensional well network and extracting crude oil in foam reservoirs as described in claim 5, characterized in that, The exploitation of the foam reservoir based on the aforementioned intensified well network also includes: The bottom-hole flowing pressure of the encrypted well network is obtained as the first bottom-hole flowing pressure; The bottom-hole flowing pressure of the original horizontal well is obtained as the second bottom-hole flowing pressure; Calculate the bottom hole pressure difference between the first bottom hole pressure and the second bottom hole pressure, and adjust the bottom hole pressure difference according to the operating time of the densified well network.

Images