Reinforced drainage composite oil recovery method for deep strong edge water heavy oil reservoir

Abstract

The invention discloses a deep strong-edge-water heavy oil reservoir enhanced drainage composite oil recovery method. The method comprises the following steps that 101, a deep strong-edge-water heavy oil reservoir suitable for drainage composite oil recovery is selected; 102, a plurality of horizontal wells are arranged on the lower portion of the oil reservoir, and a plurality of vertical wells are arranged on the upper middle portion of the oil reservoir; 103, performing steam injection single well huff-puff for a plurality of periods until thermal interference occurs between the wells; 104, all the wells are switched into a simultaneous injection and simultaneous production mode until thermal communication is achieved between the wells; step 105, switching to a reinforced driving and discharging composite mode of vertical well steam injection and non-condensate gas or solvent slug and horizontal well oil extraction for production; the method is suitable for the technical field of oil field development, it can be guaranteed that a good development effect is achieved, and economical and effective development of the deep strong edge water heavy oil reservoir is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of oilfield development, and in particular relates to a composite oil production method for enhanced flooding of a deep-layer strong edge water heavy oil reservoir. Background Art

[0002] Shengli Oilfield has 55.91 million tons of thick heavy oil reservoirs such as Dan 2, Dan 10 and Dan 113, which are characterized by "deep burial" (1100-1300m), "thick oil layer" (10-60m), and "large water body" (water body multiple >5). Affected by the heavy oil and active edge and bottom water, the steam huff and puff recovery is low, and a large amount of residual oil is retained underground and cannot be recovered. It is urgent to tackle the problem of improving the recovery rate, and steam-assisted gravity drainage (SAGD) technology is an effective way to exploit thick and ultra-heavy oil reservoirs. In foreign countries, SAGD has been widely used in shallow layers of 500m, and the field recovery rate has reached 50% to 60%. The Liaohe Oilfield in China has made a breakthrough in SAGD of ultra-heavy oil in medium and deep layers of Du 84 and shallower than 900m, and has gradually promoted industrialization in Shuyi District. The production scale has steadily increased. In 2017, the annual oil production of SAGD reached 1.06 million tons, accounting for 40% of the total heavy oil production.

[0003] Invention patent CN105649588B discloses a method for exploiting heavy oil reservoirs using SAGD. It includes: step 1, setting a vertical well at a position where at least part of the steam chamber is not developed above the horizontal section of the injection well; step 2, injecting steam into the vertical well and the injection well, and using the production well to produce oil. In the later stage of SAGD, the invention sets a vertical well at a position where no steam chamber is developed, and injects steam into the vertical well, and then uses the heat of steam to promote the development of no steam chamber, thereby achieving the effect of uniform development of steam chambers in the horizontal section, but it cannot solve the problem of difficulty in expanding steam chambers and high risk of water invasion in deep strong edge water heavy oil reservoirs.

[0004] Patent application CN111364961A is a super-heavy oil SAGD production method. It includes: step 1, setting a steam injection well and a production well, and both the steam injection well and the production well extend to the super-heavy oil reservoir; step 2, introducing steam into the super-heavy oil reservoir through the steam injection well and / or the production well to form a steam chamber in the super-heavy oil reservoir; step 3, determining the position of the interlayer in the super-heavy oil reservoir, and setting a tool lowering well, and extending the tool lowering well to the position of the interlayer; step 4, lowering the injection tool to the position of the interlayer through the tool lowering well; step 5, injecting sand-containing fluid into the interlayer through the injection tool to form cracks inside the interlayer, and allowing the steam chamber to break through the interlayer through the cracks. This invention solves the problem of low SAGD production efficiency and low oil-gas ratio in super-heavy oil reservoirs with interlayers, but cannot solve the problem of difficulty in expanding the steam chamber and high risk of water invasion in deep-layer strong edge water heavy oil reservoirs.

[0005] SAGD technology mainly uses the latent heat of steam to heat the oil reservoir, which requires high bottom hole dryness and low reservoir pressure. However, Shengli's thick and heavy oil is buried deep (low bottom hole dryness), the water body energy is relatively large (high reservoir pressure), and the oil reservoir has a certain amount of water invasion (local water invasion channels have been formed). The use of SAGD for development faces the problems of difficulty in expanding the steam chamber and high risk of water invasion. Summary of the invention

[0006] The purpose of the present invention is to overcome the defects of the existing SAGD technology and provide a composite oil recovery method for enhanced flooding in deep-layer strong edge water heavy oil reservoirs.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] A composite oil recovery method for enhanced flooding in a deep layer heavy oil reservoir with strong edge water, comprising the following steps:

[0009] Step 101: Select a deep layer strong edge water heavy oil reservoir suitable for flooding composite oil recovery;

[0010] Step 102: setting a plurality of horizontal wells in the lower part of the oil reservoir and setting a plurality of vertical wells in the middle and upper part of the oil 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 among the wells;

[0013] Step 105: switching to vertical well steam injection + non-condensable gas or solvent slug, and horizontal well oil production in an enhanced flooding composite mode;

[0014] Step 106: Production is terminated until it is no longer economically profitable.

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

[0016] Preferably, in step 101, the screening criteria for flooding composite oil recovery reservoirs are: burial depth ≤ 1300 m, continuous oil layer thickness ≥ 15 m, net-to-total thickness ratio ≥ 0.7, and plane permeability ≥ 1000×10 -3 μm 2 , vertical permeability ≥500×10 -3 μm 2 , oil saturation ≥ 0.5, 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 oil reservoir, and six vertical wells are set in the middle and upper part of the oil reservoir.

[0018] Preferably, in step 102, a horizontal well is set in the selected deep strong edge water heavy oil reservoir at a dimensionless distance of 0.2 from the bottom of the oil layer, and a row of vertical wells is set at 35 to 40 m on both sides of the horizontal well on the plane, with 3 wells in each row.

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

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

[0021] Preferably, in step 103, steam injection and huff-and-puff production are performed on one horizontal well and six vertical wells respectively, until more than one vertical well on each side thermally interferes with the horizontal well.

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

[0023] Preferably, in step 104, after thermal interference occurs in the single well throughput, a simultaneous steam injection and production mode of simultaneous steam injection, simultaneous well shutoff, and simultaneous production is implemented for one horizontal well and six vertical wells.

[0024] Preferably, in step 104, the steam injection intensity of each well is 2 to 3 times 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 criterion for determining whether thermal connectivity is achieved between wells is that the formation temperature between vertical and horizontal wells reaches above 80°C.

[0026] Preferably, in step 104, numerical simulation is used to predict the number of simultaneous injection and simultaneous production cycles required to achieve thermal interconnection between wells, that is, the timing for the reservoir to switch to enhanced flooding and drainage composite oil production.

[0027] Preferably, in the step 105, during the enhanced flooding and composite oil recovery stage, whether the vertical well is injected with steam and non-condensable gas or solvent slugs 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 formation temperature is <10000 mPa·s, it is more economical to select the non-condensate gas N2 plug, and when the viscosity of the degassed crude oil at the formation temperature is >10000 mPa·s, the solvent n-hexane plug is selected to ensure the oil recovery effect.

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

[0030] Preferably, in step 105, the steam injection rate of each vertical well is 150 m / s and the bottom dryness is required to be above 0.7. 3 / d; the injection rate of N2 is 100m 3 / d, the slug size is 0.5PV; the injection rate of n-hexane is 50m 3 / d, the slug size is 0.3PV, and the horizontal well 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 lower than 0.12.

[0032] Preferably, in step 106, the instantaneous oil-steam ratio is calculated based on the daily measured horizontal well oil production and vertical well steam injection volume. When the oil-steam ratio is lower than 0.12, the enhanced flooding composite oil production method of vertical well injection into horizontal well oil production is no longer economically beneficial 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 the present invention, on the basis of dual horizontal well SAGD, by changing the injection and production mode to vertical well steam injection and horizontal well oil production, the connection and expansion of the steam chamber in the upper part of the oil layer are accelerated, and at the same time, by adding non-condensable gas or solvent plug auxiliary steam, an enhanced flooding composite oil production method is formed, which can ensure a better development effect, so as to realize the economical and efficient development of deep strong edge water heavy oil reservoirs. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 is a flow chart of the present invention;

[0036] Figure 2 It is a schematic diagram of a longitudinal section of a vertical-horizontal well in a specific embodiment of the present invention;

[0037] Figure 3 It is a diagram of the reservoir temperature field when the thermal connection between wells in the vertical-horizontal well co-injection and co-production mode is achieved in the numerical simulation prediction in the specific embodiment of the present invention;

[0038] Figure 4 It is the instantaneous oil-gas ratio variation curve of the vertical-horizontal well enhanced flooding composite oil production stage in the specific embodiment of the present invention. DETAILED DESCRIPTION

[0039] The following is combined with Figure 1-4, further illustrating a specific implementation of the method for enhanced flooding and composite oil production in a deep layer strong edge water heavy oil reservoir of the present invention. The method for enhanced flooding and composite oil production in a deep layer strong edge water heavy oil reservoir of the present invention is not limited to the description of the following embodiments.

[0040] Embodiment 1:

[0041] A composite oil recovery method for enhanced flooding in a deep layer heavy oil reservoir with strong edge water, such as Figure 1 As shown, the following steps are included:

[0042] Step 101: Select a deep layer strong edge water heavy oil reservoir suitable for flooding composite oil recovery;

[0043] Step 102: setting a plurality of horizontal wells in the lower part of the oil reservoir and setting a plurality of vertical wells in the middle and upper part of the oil 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 among the wells;

[0046] Step 105: switching to vertical well steam injection + non-condensable gas or solvent slug, and horizontal well oil production in an enhanced flooding composite mode;

[0047] Step 106: Production is terminated until it is no longer economically profitable.

[0048] Embodiment 2:

[0049] A method for enhanced flooding composite oil production in a deep strong edge water heavy oil reservoir, wherein the other steps are similar to those in Example 1. Further, in step 101, a SAGD well group conceptual model of a vertical-horizontal well combination in a deep strong edge water heavy oil reservoir is established, the SAGD development effect of different reservoir parameters is predicted, the limits of various reservoir parameters are determined according to the principle of positive economic benefits, and a screening standard for flooding composite oil production reservoirs is obtained.

[0050] Furthermore, in step 101, the selection criteria for flooding composite oil recovery reservoirs are: burial depth ≤ 1300 m, continuous oil layer thickness ≥ 15 m, net-to-total thickness ratio ≥ 0.7, and plane permeability ≥ 1000×10 -3 μm 2 , vertical permeability ≥500×10 -3 μm 2 , oil saturation ≥ 0.5, viscosity of degassed crude oil at formation temperature ≤ 30000 mPa·s.

[0051] Embodiment 3:

[0052] A composite oil recovery method for enhanced drainage in a deep strong edge water heavy oil reservoir, wherein the 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 part of the reservoir.

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

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

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

[0056] Embodiment 4:

[0057] A method for enhanced flooding composite oil production in a deep strong edge water heavy oil reservoir, wherein the other steps are similar to those in Example 3. Further, 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 vertical wells is set at 38 m on both sides of the horizontal well on the plane, with 3 wells in each row.

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

[0059] Embodiment 5:

[0060] A method for enhanced flooding composite oil production in a deep strong edge water heavy oil reservoir, wherein the other steps are similar to those in Example 3. Further, 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 vertical wells is set at 40 m on both sides of the horizontal well on the plane, with 3 wells in each row.

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

[0062] Embodiment 6:

[0063] A method for enhanced flooding and composite oil production in a deep strong edge water heavy oil reservoir, wherein the other steps are similar to those in Example 1. Further, in step 103, steam injection and huff-and-puff production are respectively performed on one horizontal well and six vertical wells until more than one vertical well on each side thermally interferes with the horizontal well.

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

[0065] Embodiment 7:

[0066] A method for enhanced flooding and composite oil production in a deep strong edge water heavy oil reservoir, wherein the other steps are similar to those in Example 1. Further, in step 104, after thermal interference occurs in the single well throughput, one horizontal well and six vertical wells are subjected to simultaneous steam injection, simultaneous well shut-down, and simultaneous production in a simultaneous injection and production mode.

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

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

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

[0070] Embodiment 8:

[0071] A method for enhanced flooding and composite oil production in a deep strong edge water heavy oil reservoir, wherein the other steps are similar to those in Example 7. Further, in step 104, the steam injection intensity of each well is 2.5 times the steam injection intensity during single well huff and puff, and the well shut-in time is 13 days.

[0072] Embodiment 9:

[0073] A method for enhanced flooding and composite oil production in a deep strong edge water heavy oil reservoir, wherein the other steps are similar to those in Example 7. Further, in step 104, the steam injection intensity of each well is three times the steam injection intensity during single well huff and puff, and the well shut-down time is 15 days.

[0074] Embodiment 10:

[0075] A method for enhanced flooding and composite oil production in a deep strong edge water heavy oil reservoir, wherein the other steps are similar to those in Example 1. Further, in step 105, during the enhanced flooding and composite oil production stage, whether the vertical well is injected with steam and non-condensable gas or solvent slugs depends on the viscosity of the crude oil in the reservoir.

[0076] Further, in step 105, when the viscosity of the degassed crude oil at the formation temperature is <10000 mPa·s, it is more economical to select the non-condensate gas N2 plug, and when the viscosity of the degassed crude oil at the formation temperature is >10000 mPa·s, the solvent n-hexane plug is selected to ensure the oil recovery effect.

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

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

[0079] Embodiment 11:

[0080] A method for enhanced flooding composite oil recovery in a deep strong edge water heavy oil reservoir, wherein the other steps are similar to those in Example 1. Further, in step 106, the condition of no longer having economic benefits is that the oil-gas ratio is lower than 0.12.

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

[0082] Embodiment 12:

[0083] A composite oil recovery method for enhanced flooding in a deep layer heavy oil reservoir with strong edge water, such as Figure 1 As shown, a method for enhanced flooding composite oil production in a deep strong edge water heavy oil reservoir is provided. In step 101, a conceptual model of a SAGD well group of a vertical-horizontal well combination in a deep strong edge water heavy oil reservoir 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 economic benefit, and the screening criteria for flooding composite oil production reservoirs are obtained in Table 1.

[0084] Table 1 Screening criteria for flooding and drainage composite oil recovery reservoirs

[0085]

[0086] In a possible implementation, according to the flooding composite oil recovery screening criteria, the selected deep layer strong edge water heavy oil reservoir is: buried depth 1100-1230m, continuous oil layer thickness 25-50m, net-to-total thickness ratio 0.7, plane permeability 3500×10 -3 μm 2 , vertical permeability 1500×10 -3 μm 2 , oil saturation 0.47-0.58, degassed crude oil viscosity 6079-16000 mPa·s at formation temperature. The process proceeds to step 102 .

[0087] Further, 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 the horizontal section length is more than 300m. On the plane, a row of vertical wells is set at 35-40m on both sides of the horizontal well, with 3 wells in each row, and the vertical well perforation bottom boundary is 5-7m away from the horizontal well in the longitudinal direction, and the perforation top boundary is the top of the oil layer.

[0088] In a possible implementation, a horizontal well is first drilled at a location of 30m in thickness of the target reservoir, 6m from the bottom of the oil layer, with a horizontal section length of 400m. Three vertical wells are then drilled at 38m on both sides of the horizontal well, with the bottom boundary of the vertical perforation of each vertical well being 7m away from the horizontal well, and all the oil layers above the bottom boundary are perforated. Figure 2 FIG. 1 is a schematic diagram of a vertical cross-section of a vertical-horizontal well in a specific embodiment of the present invention. The process enters step 103 .

[0089] Further, in step 103, steam injection and huff-and-puff production are respectively performed on one horizontal well and six vertical wells until more than one vertical well on each side has thermal interference with the horizontal well. The criterion for determining thermal interference between the vertical well and the horizontal well is that when steam is injected into the vertical well or the horizontal well, a significant increase in the temperature of the produced fluid at the wellhead of the adjacent vertical well or the horizontal well is monitored or steam flash occurs.

[0090] In a possible implementation, when the horizontal well is subjected to single-well steam injection and huffing for the fifth cycle, it is monitored that the produced fluid of a vertical well on the left side of the horizontal well suddenly rises from 49°C to 73°C, and the water content also rises sharply from 82% to 94%, and it is determined that thermal interference occurs between the horizontal well and the vertical well; when the single-well steam injection and huffing is performed on a vertical well on the right side of the horizontal well for the sixth cycle, it is monitored that the produced fluid of the horizontal well suddenly rises from 45°C to 68°C, and the water content also rises sharply from 77% to 90%, and it is determined that thermal interference occurs between the vertical well and the horizontal well, and the steam injection and huffing mode is switched from single-well huffing to the same injection and production mode. The process enters step 104.

[0091] Furthermore, in step 104, after thermal interference occurs in the single well huff and puff, one horizontal well and six vertical wells are simultaneously injected with steam, shut down the wells, and produced simultaneously for several rounds until the formation temperature between the vertical and horizontal wells reaches above 80°C, and it is considered that thermal connection has been achieved between the wells. During simultaneous injection and production, the steam injection intensity of each well is 2 to 3 times the steam injection intensity during single well huff and puff, and the shut down time is 10 to 15 days. Numerical simulation is used to predict the number of simultaneous injection and production rounds required for the wells to achieve thermal connection, which is the time for the reservoir to enter enhanced flooding and drainage composite oil production.

[0092] In one possible implementation, a simultaneous steam injection and production mode is implemented for one horizontal well and six vertical wells. The steam injection intensity of each vertical well is increased from 100t / m during single well throughput to 200t / m, and the steam injection intensity of the horizontal well is increased from 7.5t per meter of horizontal section during single well throughput to 15t, then the total gas injection volume of the cycle is 42,000t. Due to the high steam injection intensity of simultaneous injection and production, the well holding time is appropriately extended to 12 days to better heat the formation. Numerical simulation tracks this simultaneous injection and production mode, predicting that after two rounds, the formation temperature between the vertical and horizontal wells will reach above 80°C in a large range, and then it can enter the enhanced flooding and drainage composite oil production stage. Figure 3 This is a diagram of the reservoir temperature field when the thermal connection between wells is achieved in the vertical and horizontal well co-injection and co-production mode predicted by a digital model in a specific embodiment of the present invention. The process enters step 105.

[0093] Further, in step 105, during the enhanced flooding and composite oil recovery stage, whether the vertical well is injected with steam and non-condensable gas or solvent plug depends on the crude oil viscosity of the reservoir. When the viscosity of the degassed crude oil is less than 10000 mPa·s at the formation temperature, it is more economical to select the non-condensable gas N2 plug. When the viscosity of the degassed crude oil is greater than 10000 mPa·s at the formation temperature, the solvent n-hexane plug is selected to ensure the oil recovery effect. When steam is injected,

[0094] In one possible implementation, after entering the enhanced flooding and composite oil production stage, the three vertical wells in each row are combined in pairs to form three groups. The first group is injected first. When the mine detects steam (water) leakage from any vertical well in the first group to the horizontal well, the second group of vertical wells is rotated to inject steam, and so on. The viscosity of degassed crude oil at the target reservoir formation temperature is measured to be in the range of 6079 to 16000 mPa·s, but most oil samples are <10000 mPa·s. Therefore, non-condensable gas N2 plugs are selected for steam injection, and high-dryness gas injection technology is used to ensure that the bottom-hole dryness of the steam injected into each vertical well reaches more than 0.7, and the injection rate is 150m 3 / d; the injection rate of N2 is 100m 3 / d, the slug size is 0.5PV, and the horizontal well 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 horizontal well oil production and the amount of steam injected into the vertical well (water equivalent). When the oil-steam ratio is lower than 0.12, the enhanced flooding composite oil production method of vertical well injection into horizontal well oil production is no longer economically beneficial and is stopped.

[0096] In a possible implementation, the daily oil production of horizontal wells is measured during the enhanced flooding and drainage composite production phase, and the result is divided by the total steam volume injected into the vertical wells each day to calculate the instantaneous oil-gas ratio. When the instantaneous oil-gas ratio of this group of vertical wells and horizontal wells is lower than 0.12 after 11 years of production, the net present value is negative, and the enhanced flooding and drainage composite production method of vertical wells injecting horizontal wells is stopped. Figure 4 The instantaneous oil-gas ratio variation curve of the vertical-horizontal well enhanced flooding composite oil production stage in a specific embodiment of the present invention.

[0097] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the protection scope of the present invention.

Claims

1. A composite oil recovery method for enhanced flooding in a deep, strong edge water heavy oil reservoir, characterized in that: The following steps are involved: Step 101: Select a deep layer strong edge water heavy oil reservoir suitable for flooding composite oil recovery; Step 102: setting a plurality of horizontal wells in the lower part of the oil reservoir and setting a plurality of vertical wells in the middle and upper part of the oil reservoir; Step 103: inject steam into a single well for several cycles until thermal interference occurs between wells; Step 104: All wells are switched to the same injection and production mode until thermal interconnection is achieved among the wells; Step 105: switching to vertical well steam injection + non-condensable gas or solvent slug, and horizontal well oil production in an enhanced flooding composite mode; Step 106: Production is terminated until it is no longer economically profitable.

2. The method for enhanced flooding and composite oil recovery in a deep layer strong edge water heavy oil reservoir as claimed in claim 1, characterized in that: In step 101, a conceptual model of a SAGD well group of vertical and horizontal wells in a deep strong edge water heavy oil reservoir is established, the SAGD development effect of different reservoir parameters is predicted, the limits of various reservoir parameters are determined according to the principle of positive economic benefits, and the screening criteria for flooding and drainage composite oil production reservoirs are obtained.

3. The method for enhanced flooding and composite oil recovery in a deep layer strong edge water heavy oil reservoir as claimed in claim 2, characterized in that: In step 101, the selection criteria for flooding composite oil recovery reservoirs are: burial depth ≤ 1300m, continuous oil layer thickness ≥ 15m, net-to-total thickness ratio ≥ 0.7, plane permeability ≥ 1000×10 -3 μm 2 , vertical permeability ≥500×10 -3 μm 2 , oil saturation ≥ 0.5, viscosity of degassed crude oil at formation temperature ≤ 30000 mPa·s.

4. The method for enhanced flooding and composite oil recovery in a deep layer strong edge water heavy oil reservoir as claimed in claim 1, characterized in that: 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 part of the reservoir.

5. The method for enhanced flooding and composite oil recovery in a deep layer strong edge water heavy oil reservoir as claimed in claim 1, characterized in that: In step 102, a horizontal well is set in the selected deep strong edge water heavy oil reservoir at a dimensionless distance of 0.2 from the bottom of the oil layer, and a row of vertical wells is set at 35 to 40 meters on both sides of the horizontal well, with 3 wells in each row.

6. The method for enhanced flooding and composite oil recovery in a deep layer strong edge water heavy oil reservoir as claimed in claim 5, characterized in that: In step 102, the horizontal section of the horizontal well is more than 300 m long.

7. The method for enhanced flooding and composite oil recovery in a deep layer strong edge water heavy oil reservoir as claimed in claim 5, characterized in that: In step 102, the vertical well perforation bottom boundary is 5 to 7 meters away from the horizontal well in the longitudinal direction, and the perforation top boundary is the top of the oil layer.

8. The method for enhanced flooding and composite oil recovery in a deep layer strong edge water heavy oil reservoir as claimed in claim 1, characterized in that: In step 103, steam injection and huff-and-puff production are performed on one horizontal well and six vertical wells respectively until more than one vertical well on each side has thermal interference with the horizontal well.

9. The method for enhanced flooding and composite oil recovery in a deep layer strong edge water heavy oil reservoir as claimed in claim 8, characterized in that: In step 103, the criterion for determining thermal interference between the vertical well and the horizontal well is that when steam is injected into the vertical well or the horizontal well, an increase in the temperature of the produced fluid at the wellhead of the adjacent production well is monitored or steam flashing occurs.

10. The method for enhanced flooding and composite oil recovery in a deep layer strong edge water heavy oil reservoir as claimed in claim 1, characterized in that: In step 104, after thermal interference occurs in the single well throughput, a simultaneous steam injection and production mode is implemented for one horizontal well and six vertical wells, with simultaneous steam injection, simultaneous well shut-down, and simultaneous production.

11. The method for enhanced flooding and composite oil recovery in a deep layer strong edge water heavy oil reservoir according to claim 10, characterized in that: In step 104, the steam injection intensity of each well is 2 to 3 times the steam injection intensity during single well huff and puff, and the well shut-in time is 10 to 15 days.

12. The method for enhanced flooding and composite oil recovery in a deep layer heavy oil reservoir with strong edge water as claimed in claim 1, characterized in that: In step 104, the standard for determining whether thermal communication is achieved between wells is that the formation temperature between vertical and horizontal wells reaches above 80°C.

13. The method for enhanced flooding and composite oil recovery in a deep layer strong edge water heavy oil reservoir according to claim 12, characterized in that: In step 104, numerical simulation is used to predict the number of simultaneous injection and simultaneous production cycles required to achieve thermal interconnection between wells, that is, the time for the reservoir to switch to enhanced flooding and drainage combined oil production.

14. The method for enhanced flooding and composite oil recovery in a deep layer heavy oil reservoir with strong edge water as claimed in claim 1, characterized in that: In the step 105, during the enhanced flooding and composite oil recovery stage, whether the vertical well is injected with steam as non-condensable gas or solvent slug depends on the viscosity of the crude oil in the reservoir.

15. The method for enhanced flooding and composite oil recovery in a deep layer heavy oil reservoir with strong edge water as claimed in claim 14, characterized in that: In step 105, when the viscosity of the degassed crude oil is less than 10000 mPa·s at the formation temperature, it is more economical to select a non-condensable gas N2 plug. When the viscosity of the degassed crude oil is greater than 10000 mPa·s at the formation temperature, a solvent n-hexane plug is selected to ensure the oil displacement effect.

16. The method for enhanced flooding and composite oil recovery in a deep layer heavy oil reservoir with strong edge water as claimed in claim 14, characterized in that: In step 105, the three vertical wells in each row are combined in pairs to form three groups, which are alternately injected. When steam crossover from a vertical well to the horizontal well occurs, the next group of vertical wells are rotated to inject steam.

17. The method for enhanced flooding and composite oil recovery in a deep layer heavy oil reservoir with strong edge water as claimed in claim 14, characterized in that: In step 105, the steam injection rate of each vertical well is 150m / s. 3 / d; the injection rate of N2 is 100m 3 / d, the slug size is 0.5PV; the injection rate of n-hexane is 50m 3 / d, the slug size is 0.3PV, and the horizontal well production rate is 300t / d.

18. The method for enhanced flooding and composite oil recovery in a deep layer heavy oil reservoir with strong edge water as claimed in claim 1, characterized in that: In step 106, the condition that the economic benefit is no longer achieved is that the oil-gas ratio is lower than 0.

12.

19. The method for enhanced flooding and composite oil recovery in a deep layer strong edge water heavy oil reservoir as claimed in claim 8, characterized in that: In step 106, the instantaneous oil-steam ratio is calculated based on the daily measured horizontal well oil production and vertical well steam injection. When the oil-steam ratio is lower than 0.12, the enhanced flooding composite oil production method of vertical well injection into horizontal well oil production is no longer economically beneficial and is stopped.

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