A method for enhanced drainage and composite oil recovery in a deep heavy oil reservoir with strong edge water

Abstract

The application discloses a kind of deep layer strong edge water thick oil reservoir enhanced flooding discharge composite oil extraction methods, comprising the following steps: step 101: selecting the deep layer strong edge water thick oil reservoir suitable for driving discharge composite oil extraction;Step 102: a plurality of horizontal wells are arranged in the lower part of reservoir, a plurality of straight wells are arranged in the upper part of reservoir;Step 103: steam injection single well huff and puff for several cycles until thermal interference occurs between wells;Step 104: all wells are switched to the same injection and production mode until thermal communication is achieved between wells;Step 105: switch to the enhanced flooding discharge composite mode of straight well steam injection + non-condensate gas or solvent slug and horizontal well oil production;Step 106: production until it is no longer economically viable, and production ends.The application is suitable for oilfield development technical field, and can ensure better development results to achieve economic and effective development of deep layer strong edge water thick oil reservoir.

Description

Technical Field

[0001] This invention belongs to the field of oilfield development technology, specifically a combined method for enhanced displacement and drainage of deep, heavily water-rich, heavy oil reservoirs. Background Technology

[0002] Shengli Oilfield has 55.91 million tons of thick heavy oil reservoirs, including the Single 2, Single 10, and Single 113. These reservoirs are characterized by deep burial (1100-1300m), thick oil layers (10-60m), and large water volumes (water volume ratio >5). Due to the high viscosity of the oil and active edge and bottom water, steam injection recovery is low, resulting in a large amount of residual oil remaining underground. There is an urgent need to develop technologies to improve oil recovery rates. Steam-assisted gravity drainage (SAGD) technology is an effective way to exploit thick, extra-heavy oil reservoirs. Internationally, SAGD has been widely commercialized in shallow reservoirs (below 500m), achieving field recovery rates of 50%-60%. Domestically, Liaohe Oilfield has made breakthroughs in SAGD for medium-deep extra-heavy oil reservoirs (below 900m), such as the Du 84 block, and is gradually promoting industrialization in the Shuyi area. Production has steadily increased, reaching 1.06 million tons in 2017, accounting for 40% of total heavy oil production.

[0003] Invention patent CN105649588B describes a method for exploiting heavy oil reservoirs using SAGD (Super Aquatic Gas Diversion). It includes: Step 1, setting up a vertical well at least partially above the horizontal section of the injection well where no steam cavities have developed; Step 2, injecting steam into the vertical well and the injection well, and utilizing the production well to produce oil. This invention, in the later stages of SAGD, achieves uniform development of steam cavities in the horizontal section by setting up a vertical well at a location where no steam cavities have developed and injecting steam into the vertical well, thereby utilizing the heat of the steam to promote the development of steam cavities. However, it cannot solve the problems of high difficulty in expanding steam cavities and high risk of water intrusion in deep, heavily water-affected heavy oil reservoirs.

[0004] Patent application CN111364961A describes a method for SAGD (Super Aggregate Diffusion) extraction of extra-heavy oil. It includes: Step 1, setting up a steam injection well and a production well, both extending into the extra-heavy oil reservoir; Step 2, introducing steam into the extra-heavy oil reservoir through the steam injection well and / or the production well to form a steam cavity within the reservoir; Step 3, determining the location of an interlayer within the extra-heavy oil reservoir and setting up a tool lowering well, extending it to the location of the interlayer; Step 4, lowering a jetting tool through the tool lowering well to the location of the interlayer; Step 5, injecting sand-bearing fluid into the interlayer using the jetting tool to create fractures within the interlayer, allowing the steam cavity to penetrate the interlayer through these fractures. This invention solves the problems of low SAGD extraction efficiency and low oil-steam ratio in extra-heavy oil reservoirs with interlayers, but it cannot solve the problems of difficulty in expanding the steam cavity and high risk of water intrusion in deep, strongly edge-water-rich heavy oil reservoirs.

[0005] SAGD technology mainly utilizes the latent heat of steam to heat the reservoir, requiring high bottom hole dryness and low reservoir pressure. However, the Shengli thick heavy oil reservoir is deeply buried (low bottom hole dryness) and has large water energy (high reservoir pressure). The reservoir already has a certain degree of water invasion (local water invasion channels have formed). Therefore, the development of the reservoir using SAGD faces the problems of difficulty in expanding the steam chamber and high risk of water invasion. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of existing SAGD technology and provide a combined enhanced displacement and drainage method for deep, strong edge water heavy oil reservoirs.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A combined enhanced oil recovery method for deep, heavily edge-water-rich, heavy oil reservoirs includes the following steps:

[0009] Step 101: Select a deep, strong edge water heavy oil reservoir suitable for combined oil recovery and drainage;

[0010] Step 102: Set up several horizontal wells in the lower part of the reservoir and several vertical wells in the middle and upper part of the reservoir;

[0011] Step 103: Inject steam into a single well for several cycles until thermal interference occurs between wells;

[0012] Step 104: All wells are switched to the same injection and production mode until thermal interconnection is achieved between wells;

[0013] Step 105: Switch to vertical well steam injection + non-condensate gas or solvent slug, and produce oil using a combined enhanced displacement and drainage method in horizontal well production;

[0014] Step 106: Produce until it is no longer economically viable, then end production.

[0015] Preferably, in step 101, a conceptual model of a deep, strong-edge-water, heavy oil reservoir with vertical-horizontal well combination SAGD well group is established, the SAGD development effect of different reservoir parameters is predicted, and the limits of various reservoir parameters are determined according to the principle of positive economic benefits, so as to obtain the screening criteria for reservoirs with combined displacement and drainage production.

[0016] Preferably, in step 101, the selection criteria for reservoirs in the combined oil recovery and drainage process are: burial depth ≤ 1300m, continuous oil layer thickness ≥ 15m, net-total thickness ratio ≥ 0.7, and planar permeability ≥ 1000 × 10⁻⁶. -3 μm 2 Vertical permeability ≥ 500 × 10 -3 μm 2 Oil saturation ≥ 0.5, and the viscosity of degassed crude oil at formation temperature ≤ 30000 mPa·s.

[0017] Preferably, in step 102, one horizontal well is set in the lower part of the reservoir, and six vertical wells are set in the middle and upper parts of the reservoir.

[0018] Preferably, in step 102, a horizontal well is set at a dimensionless distance of 0.2 from the bottom of the oil layer in the selected deep, strong-edge-water heavy oil reservoir, and a row of three vertical wells is set at a distance of 35-40m on each side of the horizontal well.

[0019] Preferably, in step 102, the horizontal section of the horizontal well is more than 300m long.

[0020] Preferably, in step 102, the distance between the bottom boundary of the vertical well perforation and the longitudinal distance between the vertical well and the horizontal well is 5 to 7 m, and the top boundary of the perforation is the top of the oil layer.

[0021] Preferably, in step 103, steam injection and steam discharge are carried out on one horizontal well and six vertical wells respectively until there is at least one vertical well on each side that causes thermal interference with the horizontal well.

[0022] Preferably, in step 103, the criterion for determining thermal interference between vertical wells and horizontal wells is that when steam is injected into a vertical well or a horizontal well, the temperature of the produced fluid at the wellhead of an adjacent production well rises or steam flash occurs.

[0023] Preferably, in step 104, after thermal interference occurs during single-well steam injection, a simultaneous injection and extraction mode is implemented for one horizontal well and six vertical wells, involving simultaneous steam injection, simultaneous well shut-off, and simultaneous extraction.

[0024] Preferably, in step 104, the steam injection intensity of each well is 2 to 3 times that of the steam injection intensity during single-well huff and puff, and the well shut-in time is 10 to 15 days.

[0025] Preferably, in step 104, the standard for determining that thermal interconnection has been achieved between wells is that the formation temperature between the vertical and horizontal wells reaches 80°C or higher.

[0026] Preferably, in step 104, the number of injection and production cycles required to achieve thermal interconnection between wells is predicted by numerical simulation, which is the timing for the reservoir to transition to enhanced flooding and drainage combined oil recovery.

[0027] Preferably, in step 105, during the enhanced displacement and combined oil recovery stage, whether the vertical well is accompanied by steam injection of non-condensate gas or solvent slug depends on the viscosity of the crude oil in the reservoir.

[0028] Preferably, in step 105, when the viscosity of the degassed crude oil at the local formation temperature is <10000 mPa·s, it is more economical to select the non-condensate gas N2 slug; when the viscosity of the degassed crude oil at the local formation temperature is >10000 mPa·s, the solvent n-hexane slug is selected to ensure the oil displacement effect.

[0029] Preferably, in step 105, the three vertical wells in each row are combined in pairs to form three groups, and steam is injected alternately. When steam leakage occurs from a vertical well to a horizontal well, the next group of vertical wells is rotated for steam injection.

[0030] Preferably, in step 105, the bottom dryness of the steam injection in each vertical well is required to be above 0.7, and the injection rate is 150m. 3 / d; the accompanying N2 injection rate is 100m 3 / d, slug size is 0.5PV; the accompanying hexane injection rate is 50m 3 / d, slug size is 0.3PV, horizontal well fluid production rate is 300t / d.

[0031] Preferably, in step 106, the condition that no longer has economic benefits is that the oil-gas ratio is less than 0.12.

[0032] Preferably, in step 106, the instantaneous oil-steam ratio is calculated based on the daily measured oil production from horizontal wells and the steam injection from vertical wells. When the ratio is lower than 0.12, the enhanced displacement and drainage combined oil production method of vertical well injection into horizontal wells no longer has economic benefits, and this oil production method is stopped.

[0033] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0034] In this invention, based on dual-horizontal well SAGD, a vertical-horizontal well SAGD is constructed by changing the injection and production mode to vertical well steam injection and horizontal well oil production. This accelerates the connection and expansion of the steam chamber in the upper part of the oil layer. At the same time, by adding non-condensate gas or solvent slugs to assist steam, a combined enhanced displacement and drainage oil production method is formed, which can ensure better development results and achieve economical and effective development of deep, strong edge water heavy oil reservoirs. Attached Figure Description

[0035] Figure 1 This is a flowchart of the present invention;

[0036] Figure 2 This is a schematic diagram of the longitudinal profile of a straight-horizontal well in a specific embodiment of the present invention;

[0037] Figure 3 This is a reservoir temperature field diagram in a specific embodiment of the present invention, showing the thermal interconnection between vertical and horizontal wells in a co-injection and co-production mode.

[0038] Figure 4 The image shows the instantaneous oil-gas ratio change curve during the enhanced displacement and drainage combined oil production stage in a specific embodiment of the present invention. Detailed Implementation

[0039] The following is in conjunction with the appendix Figure 1-4This invention further illustrates specific embodiments of a combined enhanced displacement and drainage method for deep, heavily water-rich, and deep oil reservoirs. The method is not limited to the descriptions in the following embodiments.

[0040] Example 1:

[0041] A combined enhanced displacement and recovery method for deep, heavily edged water heavy oil reservoirs, such as... Figure 1 As shown, it includes the following steps:

[0042] Step 101: Select a deep, strong edge water heavy oil reservoir suitable for combined oil recovery and drainage;

[0043] Step 102: Set up several horizontal wells in the lower part of the reservoir and several vertical wells in the middle and upper part of the reservoir;

[0044] Step 103: Inject steam into a single well for several cycles until thermal interference occurs between wells;

[0045] Step 104: All wells are switched to the same injection and production mode until thermal interconnection is achieved between wells;

[0046] Step 105: Switch to vertical well steam injection + non-condensate gas or solvent slug, and produce oil using a combined enhanced displacement and drainage method in horizontal well production;

[0047] Step 106: Produce until it is no longer economically viable, then end production.

[0048] Example 2:

[0049] A method for enhanced displacement and drainage combined oil recovery in deep, strong-edge-water heavy oil reservoirs is described. Other steps are similar to those in Example 1. Further, in step 101, a conceptual model of a vertical-horizontal well combination SAGD well group is established for deep, strong-edge-water heavy oil reservoirs. The SAGD development effect of different reservoir parameters is predicted. Based on the principle of positive economic benefits, the limits of various reservoir parameters are determined to obtain the screening criteria for reservoirs in enhanced displacement and drainage combined oil recovery.

[0050] Furthermore, in step 101, the screening criteria for reservoirs in combined oil recovery and drainage are: burial depth ≤ 1300m, continuous oil layer thickness ≥ 15m, net-total thickness ratio ≥ 0.7, and planar permeability ≥ 1000 × 10⁻⁶. -3 μm 2 Vertical permeability ≥ 500 × 10 -3 μm 2 Oil saturation ≥ 0.5, and the viscosity of degassed crude oil at formation temperature ≤ 30000 mPa·s.

[0051] Example 3:

[0052] A combined method for enhanced displacement and drainage of deep, heavily water-rich, heavy oil reservoirs is proposed. Other steps are similar to those in Example 1. Further, in step 102, one horizontal well is set in the lower part of the reservoir, and six vertical wells are set in the middle and upper parts of the reservoir.

[0053] Furthermore, in step 102, a horizontal well is set at a dimensionless distance of 0.2 from the bottom of the oil layer in the selected deep, strong edge water heavy oil reservoir. A row of vertical wells with 3 wells is set at a distance of 35m from both sides of the horizontal well on the plane.

[0054] Furthermore, in step 102, the horizontal section of the horizontal well is more than 300m long.

[0055] Furthermore, in step 102, the vertical well perforation bottom boundary is 5m from the horizontal well longitudinal distance, and the perforation top boundary is the top of the oil layer.

[0056] Example 4:

[0057] A method for enhanced displacement and drainage combined oil recovery in deep, strong-edge-water heavy oil reservoirs, with other steps similar to those in Example 3, further wherein in step 102, a horizontal well is set at a dimensionless distance of 0.2 from the bottom of the oil layer in the selected deep, strong-edge-water heavy oil reservoir, and a row of three vertical wells is set at a distance of 38m from each side of the horizontal well on the plane.

[0058] Furthermore, in step 102, the vertical well perforation bottom boundary is 6m from the horizontal well longitudinal distance, and the perforation top boundary is the top of the oil layer.

[0059] Example 5:

[0060] A method for enhanced displacement and drainage combined oil recovery in deep, strong-edge-water heavy oil reservoirs, with other steps similar to those in Example 3, further wherein in step 102, a horizontal well is set at a dimensionless distance of 0.2 from the bottom of the oil layer in the selected deep, strong-edge-water heavy oil reservoir, and a row of three vertical wells is set at a distance of 40m on each side of the horizontal well on the plane.

[0061] Furthermore, in step 102, the vertical well perforation bottom boundary is 7m from the horizontal well longitudinal distance, and the perforation top boundary is the top of the oil layer.

[0062] Example 6:

[0063] A combined enhanced displacement and drainage method for deep, strong-edge-water heavy oil reservoirs, with other steps similar to those in Example 1, further wherein in step 103, steam injection and huff-and-puff production are carried out on one horizontal well and six vertical wells respectively, until at least one vertical well and one horizontal well on each side cause thermal interference.

[0064] Furthermore, in step 103, the criterion for determining thermal interference between vertical wells and horizontal wells is that when steam is injected into a vertical or horizontal well, the temperature of the produced fluid at the wellhead of the adjacent production well rises or steam flash occurs.

[0065] Example 7:

[0066] A combined oil recovery method for enhanced displacement and drainage in deep, heavily water-rich, heavy oil reservoirs, with other steps similar to those in Example 1, further includes step 104, in which, after thermal interference occurs during single-well injection and simmering, a simultaneous injection and extraction mode is implemented for one horizontal well and six vertical wells.

[0067] Furthermore, in step 104, the steam injection intensity of each well is twice that of the steam injection intensity during single-well huff and puff, and the well shut-in time is 10 days.

[0068] Furthermore, in step 104, the standard for determining that thermal interconnection between wells is achieved is that the formation temperature between the vertical and horizontal wells reaches 80°C or higher.

[0069] Furthermore, in step 104, numerical simulation is used to predict the number of injection and production cycles required to achieve thermal interconnection between wells, which is the timing for the reservoir to transition to enhanced flooding and drainage combined oil recovery.

[0070] Example 8:

[0071] A combined enhanced displacement and drainage method for deep, strong edge water heavy oil reservoirs, with other steps similar to those in Example 7, further wherein in step 104, the steam injection intensity of each well is 2.5 times that of the steam injection intensity during single-well huff and puff, and the well shut-in time is 13 days.

[0072] Example 9:

[0073] A combined enhanced displacement and drainage method for deep, strong edge water heavy oil reservoirs, with other steps similar to those in Example 7, further wherein in step 104, the steam injection intensity of each well is three times that of a single well during huff and puff, and the well shut-in time is 15 days.

[0074] Example 10:

[0075] A method for enhanced displacement and drainage combined oil recovery in deep, strong edge water heavy oil reservoirs, with other steps similar to those in Example 1. Further, in step 105, during the enhanced displacement and drainage combined oil recovery stage, whether to inject non-condensate gas or solvent slug with steam in the vertical well depends on the viscosity of the crude oil in the reservoir.

[0076] Furthermore, in step 105, when the viscosity of the degassed crude oil at the local formation temperature is <10000mPa·s, it is more economical to choose the non-condensate gas N2 slug; when the viscosity of the degassed crude oil at the local formation temperature is >10000mPa·s, the solvent n-hexane slug is chosen to ensure the oil displacement effect.

[0077] Furthermore, in step 105, the three vertical wells in each row are combined in pairs to form three groups, and steam is injected alternately. When steam leakage occurs from a vertical well to a horizontal well, the next group of vertical wells is rotated for steam injection.

[0078] Furthermore, in step 105, the bottom dryness of the steam injection into each vertical well must be above 0.7, and the injection rate must be 150m. 3 / d; the accompanying N2 injection rate is 100m 3 / d, slug size is 0.5PV; the accompanying hexane injection rate is 50m 3 / d, slug size is 0.3PV, horizontal well fluid production rate is 300t / d.

[0079] Example 11:

[0080] A combined enhanced displacement and drainage method for deep, strong edge water heavy oil reservoirs, with other steps similar to those in Example 1, further wherein in step 106, the condition that no longer has economic benefits is that the oil-gas ratio is less than 0.12.

[0081] Furthermore, in step 106, the instantaneous oil-steam ratio is calculated based on the daily measured oil production from horizontal wells and the steam injection from vertical wells. When the ratio is lower than 0.12, the enhanced displacement and drainage combined oil production method of vertical well injection into horizontal wells is no longer economically viable, and this oil production method is stopped.

[0082] Example 12:

[0083] A combined enhanced displacement and recovery method for deep, heavily edged water heavy oil reservoirs, such as... Figure 1 As shown, a combined enhanced displacement and drainage method for deep, strong-edge-water heavy oil reservoirs is described. In step 101, a conceptual model of a vertical-horizontal well combination SAGD well group is established for deep, strong-edge-water heavy oil reservoirs. The SAGD development effect of different reservoir parameters is predicted. Based on the principle of economic benefits, the limits of various reservoir parameters are determined, and the screening criteria for combined displacement and drainage oil reservoirs are obtained in Table 1.

[0084] Table 1 Screening Criteria for Oil Reservoirs with Combined Exhaust and Drainage Recovery

[0085]

[0086] In one possible implementation, based on the screening criteria for combined oil recovery and drainage, the selected deep, strong edge water heavy oil reservoir is characterized by: a burial depth of 1100–1230 m, a continuous oil layer thickness of 25–50 m, a net-total thickness ratio of 0.7, and a planar permeability of 3500 × 10⁻⁶ m. -3 μm 2 Vertical permeability 1500×10 -3 μm 2 The oil saturation is 0.47–0.58, and the viscosity of the degassed crude oil at the formation temperature is 6079–16000 mPa·s. The process proceeds to step 102.

[0087] Furthermore, in step 102, a horizontal well is installed at a dimensionless distance of 0.2 from the bottom of the oil layer in the selected deep, strong-edge-water heavy oil reservoir, with a horizontal section length of more than 300m. A row of three vertical wells is installed on each side of the horizontal well at a distance of 35-40m from both sides. The bottom boundary of the vertical well perforation is 5-7m from the longitudinal distance of the horizontal well, and the top boundary of the perforation is the top of the oil layer.

[0088] In one possible implementation, a horizontal well with a length of 400m is first drilled at a location 30m thick in the target reservoir, 6m from the bottom of the oil layer. Then, three vertical wells are drilled 38m apart on each side of the horizontal well. The bottom boundary of the longitudinal perforation of each vertical well is 7m from the longitudinal distance of the horizontal well, and the oil layer above the bottom boundary is completely perforated. Figure 2 This is a schematic diagram of a longitudinal section of a straight-horizontal well in a specific embodiment of the present invention. The process proceeds to step 103.

[0089] Furthermore, in step 103, steam injection and huff-and-puff production are carried out on one horizontal well and six vertical wells respectively, until at least one vertical well and one horizontal well on each side experience thermal interference. The criterion for determining thermal interference between vertical and horizontal wells is that a significant increase in the temperature of the produced fluid at the wellhead or the occurrence of steam flashing is detected when steam is injected into the vertical or horizontal well.

[0090] In one possible implementation, when single-well steam injection huff and puff is performed on a horizontal well for the 5th cycle, it is detected that the produced fluid temperature of a vertical well to the left of the horizontal well suddenly rises from 49°C to 73°C, and the water cut also rises sharply from 82% to 94%, indicating thermal interference between the horizontal well and the vertical well. When single-well steam injection huff and puff is performed on a vertical well to the right of the horizontal well for the 6th cycle, it is detected that the produced fluid temperature of the horizontal well suddenly rises from 45°C to 68°C, and the water cut also rises sharply from 77% to 90%, indicating thermal interference between the vertical well and the horizontal well. The steam injection huff and puff mode is then switched from single-well huff and puff to simultaneous injection and production mode. The process proceeds to step 104.

[0091] Furthermore, in step 104, after thermal interference occurs during single-well injection and production, simultaneous steam injection, well shut-in, and production are carried out on one horizontal well and six vertical wells in several rounds until the formation temperature between the vertical and horizontal wells reaches above 80°C. This is considered to indicate that thermal interconnection has been achieved between the wells. During simultaneous injection and production, the steam injection intensity of each well is 2 to 3 times that during single-well injection and production, and the shut-in time is 10 to 15 days. Numerical simulation is used to predict the number of rounds of simultaneous injection and production required to achieve thermal interconnection between the wells; this is the opportune moment for the reservoir to transition to enhanced displacement and drainage combined oil recovery.

[0092] In one possible implementation, a simultaneous steam injection, well shut-in, and production mode is implemented for one horizontal well and six vertical wells. The steam injection intensity for each vertical well is increased from 100 t / m during single-well injection to 200 t / m, and the steam injection intensity for each horizontal well is increased from 7.5 t / m per meter of horizontal section during single-well injection to 15 t / m, resulting in a total gas injection volume of 42,000 t / m. Due to the high steam injection intensity during simultaneous injection and production, the well shut-in time is appropriately extended to 12 days to better heat the formation. Numerical simulations tracking this simultaneous injection and production mode predict that after two rounds, the formation temperature between the vertical and horizontal wells will reach above 80°C over a wide range, at which point the process can transition to the enhanced displacement and drainage combined oil recovery stage. Figure 3 This is a reservoir temperature field diagram in a specific embodiment of the present invention, showing the thermal interconnection between wells in a vertical-horizontal well co-injection and co-production mode, predicted by numerical model. The process proceeds to step 105.

[0093] Furthermore, in step 105, during the enhanced displacement and recovery stage, whether to inject non-condensate gas or a solvent slug into the vertical well with steam depends on the viscosity of the crude oil in the reservoir. When the viscosity of the degassed crude oil at the formation temperature is <10000 mPa·s, the non-condensate gas N2 slug is more economical. When the viscosity of the degassed crude oil at the formation temperature is >10000 mPa·s, the solvent n-hexane slug is selected to ensure the oil displacement effect. During steam injection,

[0094] In one possible implementation, after transitioning to the enhanced displacement and drainage combined oil recovery stage, the three vertical wells in each row are paired up to form three groups. The first group is injected first. When steam (water) leakage from any vertical well in the first group to the horizontal well is detected by the field, steam injection is switched to the second group of vertical wells, and so on. The measured viscosity of the degassed crude oil at the target reservoir formation temperature ranges from 6079 to 16000 mPa·s, but most oil samples are <10000 mPa·s. Therefore, a non-condensable gas N2 slug with steam injection is selected, employing a high-dryness injection process to ensure that the bottom-hole dryness of each vertical well reaches above 0.7, with an injection rate of 150 m / s. 3 / d; the accompanying N2 injection rate is 100m 3 / d, slug size is 0.5PV, horizontal well fluid production rate is 300t / d. The process proceeds to step 106.

[0095] Furthermore, in step 106, the instantaneous oil-steam ratio is calculated based on the daily measured oil production from the horizontal well and the steam (water equivalent) injected into the vertical well. When the ratio is lower than 0.12, this enhanced displacement and drainage combined oil production method of vertical well injection into horizontal well is no longer economically viable, and this oil production method is stopped.

[0096] In one possible implementation, the daily oil production from horizontal wells is measured during the enhanced displacement-drainage combined oil recovery stage, and the instantaneous oil-steam ratio is calculated by dividing it by the total daily steam injection from vertical wells. When this group of vertical-horizontal wells has been producing for 11 years and the instantaneous oil-steam ratio is below 0.12 (net present value is negative), this enhanced displacement-drainage combined oil recovery method of vertical well injection into horizontal wells is discontinued. Figure 4 This is a curve showing the instantaneous oil-gas ratio change during the enhanced displacement and drainage combined oil production stage in a specific embodiment of the present invention.

[0097] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A method for enhanced recovery of heavy oil reservoirs with strong edge water, characterized in that, The method comprises the following steps: Step 101: selecting a deep strong edge water heavy oil reservoir suitable for composite oil production by drainage; Step 102: arranging a plurality of horizontal wells in the lower part of the reservoir and a plurality of vertical wells in the upper part of the reservoir; Step 103: injecting steam and carrying out single-well huff and puff for several cycles until thermal interference occurs between the wells; Step 104: switching all the wells to the same injection and production mode until thermal connection is achieved between the wells; Step 105: switching to the enhanced composite production mode of vertical well steam injection + non-condensable gas or solvent slug and horizontal well oil production; Step 106: producing until no economic benefit is obtained and ending the production; In the step 102, one horizontal well is arranged in the lower part of the reservoir and six vertical wells are arranged in the upper part of the reservoir; In the step 102, one horizontal well is arranged at a dimensionless distance of 0.2 from the bottom of the reservoir in the selected deep strong edge water heavy oil reservoir, and one row of vertical wells is arranged at a distance of 35-40 m from both sides of the horizontal well in the plane, with three vertical wells in each row; In the step 103, one horizontal well and six vertical wells are respectively subjected to steam injection and huff and puff production until there is more than one vertical well on each side that has thermal interference with the horizontal well; In the step 103, the standard for determining whether thermal interference occurs between the vertical well and the horizontal well is that the temperature of the wellhead produced liquid of the adjacent production well rises or steam flashing occurs when the vertical well or the horizontal well is injected with steam; In the step 104, the same injection and production mode is implemented for the one horizontal well and the six vertical wells after thermal interference occurs in single-well huff and puff; In the step 105, the enhanced composite production stage, whether non-condensable gas or solvent slug is injected into the vertical well along with the steam depends on the viscosity of the crude oil in the reservoir; In the step 105, when the viscosity of the degassed crude oil at the formation temperature is less than 10,000 mPa·s, it is more economical to select the non-condensable gas N2 slug, and when the viscosity of the degassed crude oil at the formation temperature is greater than 10,000 mPa·s, the solvent n-hexane slug is selected to ensure the oil displacement effect.

2. The enhanced recovery and production method of a heavy oil reservoir with a strong edge water according to claim 1, characterized in that: In the step 101, a vertical-horizontal well combined SAGD well group conceptual model of the deep strong edge water heavy oil reservoir is established, the SAGD development effect of different reservoir parameters is predicted, the reservoir parameter limits are determined according to the principle that the economic benefit is positive, and the screening standard for the composite oil production by drainage reservoir is obtained.

3. The enhanced recovery and production method of a heavy oil reservoir with a strong edge water according to claim 2, characterized in that: The drainage composite oil reservoir screening criteria in step 101 are: buried depth ≤ 1300 m, continuous oil layer thickness ≥ 15 m, net total thickness ratio ≥ 0.7, planar permeability ≥ 1000×10 -3 μm 2 , vertical permeability ≥ 500×10 -3 μm 2 , oil saturation ≥ 0.5, and degassed crude oil viscosity at formation temperature ≤ 30000 mPa·s.

4. The enhanced recovery and production method of a heavy oil reservoir with a strong edge water according to claim 1, characterized in that: In the step 102, the horizontal section length of the horizontal well is more than 300 m.

5. The enhanced recovery and production method of a heavy oil reservoir with a strong edge water according to claim 1, characterized in that: In the step 102, the vertical distance between the perforation bottom boundary of the vertical well and the horizontal well is 5-7 m, and the perforation top boundary is the top of the oil layer.

6. The enhanced recovery and production method of a heavy oil reservoir with a strong edge water according to claim 1, characterized in that: In the step 104, the steam injection intensity of each well is 2-3 times the steam injection intensity in single-well huff and puff, and the huff and puff time is 10-15 days.

7. The enhanced recovery and production method of a heavy oil reservoir with a strong edge water according to claim 1, characterized in that: In the step 104, the standard for determining whether thermal connection is achieved between the wells is that the formation temperature between the vertical-horizontal well is above 80℃.

8. The enhanced recovery and production method of a heavy oil reservoir with a strong edge water according to claim 1, characterized in that: In the step 104, the same injection and production cycles required for achieving thermal connection between the wells are predicted by numerical simulation, which is the timing for switching to the enhanced composite production by drainage.

9. The enhanced recovery and production method of a heavy oil reservoir with a strong edge water according to claim 1, characterized in that: In the step 105, the three vertical wells in each row are combined into three groups, and the steam injection is alternately carried out, and when steam channeling occurs from a certain vertical well to the horizontal well, the next group of vertical wells is switched to steam injection.

10. The enhanced recovery and production method of a heavy oil reservoir with a strong edge water according to claim 1, characterized in that: The steam injection rate of each vertical well is required to be above 0.7 at the well bottom, and the injection rate is 150 m 3 / d, and the N2 injection rate is 100 m 3 / d, and the N2 injection rate is 100 m 3 / d, and the N2 injection rate is 100 m 11. The enhanced recovery and production method of a heavy oil reservoir with a strong edge water according to claim 1, characterized in that: In the step 106, the condition that no economic benefit is obtained is that the oil-steam ratio is less than 0.

12.

12. The enhanced recovery and production method of a heavy oil reservoir with a strong edge water according to claim 1, characterized in that: In step 106, the instantaneous oil-steam ratio is calculated according to the daily metered oil production of the horizontal well and the steam injection of the vertical well. When the instantaneous oil-steam ratio is lower than 0.12, the enhanced drive and depletion composite oil production mode of the vertical well to horizontal well oil production no longer has economic benefits, and the oil production mode is stopped.

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