A deep heavy oil displacement and discharge composite rapid preheating method

Abstract

The application discloses a kind of deep heavy oil drive discharge composite quick preheating methods, comprising the following steps: step 101: in upper part of oil layer, complete several straight wells, complete horizontal well in the bottom of oil layer between several straight wells;Step 102: according to the longitudinal heterogeneity of reservoir, the density of straight well is changed Perforation;Step 103: slightly higher than the horizontal of formation fracture pressure, high-intensity steam injection is simultaneously injected into straight well and horizontal well;Step 104: after stewing well for a period of time, the next round of microfracturing high-intensity steam injection is started;Step 105: the temperature between several straight wells and between them and horizontal well is monitored, and the temperature required when the temperature of the oil in the oil layer reaches Newton fluid is exceeded, and the preheating is ended to enter the drive discharge composite production stage, the application is suitable for oilfield development technical field, by microfracturing high-intensity synchronous steam injection and synchronous short-time recovery of condensed water, the preheating of injection and production well is realized quickly and uniformly, so as to provide favorable guarantee for the success of drive discharge composite production stage.

Description

Technical Field

[0001] This invention belongs to the field of oilfield development technology, specifically a rapid preheating method for deep heavy oil displacement. Background Technology

[0002] The proven reserves of heavy oil in the eastern part of Shengli Oilfield are 620 million tons, of which 575 million tons have been utilized. The reservoirs are deep, thin, and have high water energy. Development of heavy oil in eastern Shengli is primarily based on steam injection, a single development method with low recovery rates. A shift in development methods is needed to significantly improve recovery rates. However, both steam flooding and SAGD, the two main technologies for improving heavy oil recovery, have limitations in deep heavy oil reservoirs. Steam flooding primarily relies on displacement, achieving recovery rates of 40-60%, but with a low oil-gas ratio. SAGD primarily relies on gravity drainage, achieving recovery rates of 50-70%, but with a high oil-gas ratio. Given the deep burial of Shengli heavy oil reservoirs and the difficulty in expanding the steam cavity under low dry and high pressure conditions, SAGD technology has poor adaptability. The combined flooding and drainage technology combines the advantages of both, with recovery rates close to those of steam flooding and SAGD, and an oil-to-steam ratio higher than that of steam flooding. It has lower requirements for reservoir depth and thickness than SAGD, and is suitable for a wider range of reservoir properties than steam flooding. It can be used as an effective replacement technology after high-cycle huff and puff of deep heavy oil, and can significantly improve the recovery rate of Shengli heavy oil.

[0003] Patent application CN113863908A discloses a method for improving the uniformity of steam injection in SAGD horizontal wells. It includes: for dual-tube steam injection, extending the length of the short tube in the injection well to 1 / 6 to 1 / 2 of the length of the horizontal section of the horizontal well; for multi-point steam injection, setting the number of steam injection points in the injection well to 10 to 40 and / or extending the length of the tubing in the production well to 1 / 6 to 1 / 2 of the length of the horizontal section of the horizontal well. By changing the tubing string structure, an effective method for improving the uniformity of steam injection in SAGD horizontal wells is formed. This method is applicable to SAGD production methods using horizontal well steam injection, but it cannot solve the technical problem of uniform steam injection in vertical wells using deep heavy oil displacement combined production methods.

[0004] Invention patent CN104165046B describes an enhanced method for rapid and uniform SAGD initiation. It includes: Step 1, drilling and completing the SAGD well in the rock formation; Step 2, conditioning the well to create stress conditions conducive to the formation of an expansion zone; Step 3, injecting a stimulant into one or both of the two wells under a pressure greater than the minimum in-situ stress of the rock formation to initiate the expansion zone connecting the SAGD wells, and continuously injecting the stimulant into the first well while maintaining a target pressure in the second well to ensure uniform diffusion of the expansion zone along the length of the well. This invention provides a method for establishing a laterally continuous, vertically guided expansion zone connecting two SAGD wells, but it relies on a complex downhole packer system to manage the uniform lateral extension of the expansion zone along the length of the SAGD well, requiring sophisticated technology and presenting significant implementation challenges.

[0005] Based on the development practices of steam-driven and SAGD (Super Aqueous Automated Guided Discharge) systems, to ensure development effectiveness, reservoir preheating is essential before transitioning to the steam-driven and SAGD production stages, ensuring effective thermal connectivity between injection and production wells. Steam-driven systems typically achieve some thermal connectivity through multiple rounds of single-well injection and output, but this preheating method suffers from uneven heating. SAGD generally employs steam injection circulation for preheating, but this method suffers from long preheating times and high steam consumption.

[0006] Therefore, there is an urgent need for a new preheating method that can overcome the shortcomings of existing preheating technologies such as steam drive and SAGD, and quickly achieve uniform and effective thermal connectivity between injection and production wells in deep heavy oil displacement, thus providing a guarantee for subsequent displacement and discharge combined production. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the prior art and provide a rapid preheating method for deep heavy oil displacement.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] A method for rapid preheating combined with deep heavy oil displacement includes the following steps:

[0010] Step 101: Complete drilling several vertical wells in the upper part of the oil layer, and complete drilling horizontal wells at the bottom of the oil layer between the vertical wells;

[0011] Step 102: Perform variable density perforation on the vertical well based on the longitudinal heterogeneity of the reservoir;

[0012] Step 103: Simultaneously inject high-intensity water vapor into both the vertical and horizontal wells at a level slightly higher than the formation fracturing pressure;

[0013] Step 104: After the well has been sealed for a period of time, drainage is started and the next round of micro-fracture high-intensity steam injection begins;

[0014] Step 105: If the temperature between several vertical wells and between them and the horizontal wells exceeds the temperature required for the crude oil in the oil reservoir to reach the Newtonian fluid level, the preheating is completed and the dewatering and combined production stage begins.

[0015] Preferably, in step 101, two rows of vertical wells are drilled in the upper part of the oil layer, and one horizontal well is drilled at the bottom of the oil layer between the two rows of vertical wells.

[0016] Preferably, in step 101, the completed horizontal well has a horizontal trajectory in the longitudinal direction.

[0017] Preferably, in step 101, the trajectory of the horizontal segment on the horizontal well plane must not deviate from the target center; the well inclination and the rate of change of the total angle 50m above the vertical depth of the horizontal segment meet the requirements of the combined displacement and drainage process.

[0018] Preferably, the completion and sand control processes for both vertical and horizontal wells also meet the combined requirements for drainage and sand removal.

[0019] Preferably, in step 102, the vertical well is delivered by cable and perforated under near-balanced pressure.

[0020] Preferably, in step 102, the porosity is reduced at the top of the oil layer and at the bottom where the physical properties are better.

[0021] Preferably, in step 102, perforation is carried out using an omnidirectional spiral perforation method with oil pipe delivery.

[0022] Preferably, in step 103, a supercritical steam injection boiler is used to simultaneously inject steam into both the vertical and horizontal wells.

[0023] Preferably, in step 103, the steam injection pressure is in the range of 2 to 3 MPa higher than the formation fracturing pressure.

[0024] Preferably, in step 103, the steam injection intensity of vertical and horizontal wells is increased to twice that of conventional steam huff and puff, further accelerating the thermal connection between injection and production wells.

[0025] Preferably, in step 104, the well is simmered for a period of time to allow the injected steam and the reservoir to exchange heat fully, and then each well simultaneously recovers the condensate generated after the injected steam and the reservoir exchange heat.

[0026] Preferably, in step 104, in order to shorten the preheating time, a higher liquid extraction intensity is used for recovery. When the cumulative recovered water volume reaches the water equivalent of the injected steam, the next round of high-intensity combined injection and recovery begins.

[0027] Preferably, in step 105, old wells between vertical wells and between vertical and horizontal wells are used as observation wells to monitor the reservoir temperature, ensuring that there is at least one observation well between each vertical and horizontal well.

[0028] Preferably, in step 105, when the temperature monitored by all observation wells reaches the temperature required for the crude oil in the oil layer to reach the Newtonian fluid level, it indicates that good thermal connectivity has been achieved between the injection and production wells, and the process can proceed to the combined production stage of displacement and drainage.

[0029] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0030] In this invention, based on conventional preheating, the steam chamber is expanded as uniformly as possible in both the plane and the longitudinal direction by controlling the drilling trajectory of horizontal wells and using segmented completion technology and variable density perforation in vertical wells. At the same time, rapid and uniform preheating between injection and production wells is achieved through micro-fracture high-intensity synchronous steam injection and synchronous short-time recovery of condensate, thus providing a favorable guarantee for the success of the combined production stage of displacement and drainage. Attached Figure Description

[0031] Figure 1 This is a flowchart of the present invention;

[0032] Figure 2 This is a schematic diagram of the trajectory of the stable inclination section of a horizontal well in a specific embodiment of the present invention;

[0033] Figure 3 This is a diagram of a horizontal well segmented filling sand control tubing string in a specific embodiment of the present invention;

[0034] Figure 4 This is a diagram of the completion string for a vertical well in a specific embodiment of the present invention;

[0035] Figure 5 This is a well location deployment diagram of the combined well group for drainage and expulsion in a specific embodiment of the present invention. Detailed Implementation

[0036] The following is in conjunction with the appendix Figure 1-5 This invention further illustrates specific embodiments of a deep heavy oil displacement and rapid preheating method according to the present invention. The method is not limited to the descriptions in the following embodiments.

[0037] Example 1:

[0038] A rapid preheating method for deep heavy oil displacement, such as... Figure 1 As shown, it includes the following steps:

[0039] Step 101: Complete drilling several vertical wells in the upper part of the oil layer, and complete drilling horizontal wells at the bottom of the oil layer between the vertical wells;

[0040] Step 102: Perform variable density perforation on the vertical well based on the longitudinal heterogeneity of the reservoir;

[0041] Step 103: Simultaneously inject high-intensity water vapor into both the vertical and horizontal wells at a level slightly higher than the formation fracturing pressure;

[0042] Step 104: After the well has been sealed for a period of time, drainage is started and the next round of micro-fracture high-intensity steam injection begins;

[0043] Step 105: If the temperature between several vertical wells and between them and the horizontal wells exceeds the temperature required for the crude oil in the oil reservoir to reach the Newtonian fluid level, the preheating is completed and the dewatering and combined production stage begins.

[0044] Example 2:

[0045] A method for rapid preheating combined with deep heavy oil displacement, with other steps similar to those in Example 1, further wherein in step 101, two rows of vertical wells are drilled in the upper part of the oil layer, and one horizontal well is drilled at the bottom of the oil layer between the two rows of vertical wells.

[0046] Furthermore, in step 101, the completed horizontal well has a longitudinal trajectory that ensures it is horizontal.

[0047] Furthermore, in step 101, the trajectory of the horizontal section on the horizontal well plane must not deviate from the target center; the well inclination and total angle change rate 50m above the vertical depth of the horizontal section must meet the requirements of the combined displacement and drainage process.

[0048] Furthermore, the completion and sand control processes for both vertical and horizontal wells meet the combined requirements for drainage and sand removal.

[0049] Example 3:

[0050] A method for rapid preheating combined with deep heavy oil displacement is provided. Other steps are similar to those in Example 1. Further, in step 102, the vertical well is delivered by cable and perforated under near-balanced pressure.

[0051] Furthermore, in step 102, the porosity is reduced at the top of the oil layer and at the bottom where the physical properties are better.

[0052] Furthermore, in step 102, perforation is carried out using an omnidirectional spiral perforation method with oil pipe delivery.

[0053] Example 4:

[0054] A method for rapid preheating combined with deep heavy oil displacement is provided. Other steps are similar to those in Example 1. Further, in step 103, a supercritical steam injection boiler is used to inject steam into both vertical and horizontal wells simultaneously.

[0055] Furthermore, in step 103, the steam injection pressure range is 2 to 3 MPa higher than the formation fracturing pressure.

[0056] Furthermore, in step 103, the steam injection intensity of vertical and horizontal wells is increased to twice that of conventional steam huff and puff, further accelerating the thermal connection between injection and production wells.

[0057] Example 5:

[0058] A rapid preheating method for deep heavy oil displacement is provided. Other steps are similar to those in Example 1. In step 104, the well is simmered for a period of time to allow the injected steam and the reservoir to exchange heat fully. Then, each well simultaneously recovers the condensate generated after the injected steam and the reservoir exchange heat.

[0059] Furthermore, in step 104, in order to shorten the preheating time, a higher liquid extraction intensity is used for recovery. When the cumulative recovered water volume reaches the water equivalent of the injected steam, the next round of high-intensity combined injection and recovery begins.

[0060] Example 6:

[0061] A rapid preheating method for deep heavy oil displacement is provided. Other steps are similar to those in Example 1. Further, in step 105, old wells between vertical wells and between vertical and horizontal wells are used as observation wells to monitor the oil layer temperature, ensuring that there is at least one observation well between each vertical and horizontal well.

[0062] Furthermore, in step 105, when the temperature monitored by all observation wells reaches the temperature required for the crude oil in the oil layer to reach the Newtonian fluid level, it indicates that good thermal connectivity has been achieved between the injection and production wells, and the process can proceed to the combined production stage of displacement and drainage.

[0063] Example 7:

[0064] A rapid preheating method for deep heavy oil displacement, such as... Figure 1 As shown, Figure 1 This is a flowchart of a combined rapid preheating method for deep heavy oil displacement.

[0065] In step 101, two rows of vertical wells are drilled in the upper part of the oil layer, and one horizontal well is drilled at the bottom of the oil layer between the two rows of vertical wells. To ensure the stable expansion of the steam chamber during the combined displacement and venting stage, the trajectory of the horizontal section in the vertical direction must be horizontal. Since the horizontal well is drilled between the two rows of vertical wells, the trajectory of the horizontal section in the plane must not deviate from the target center to ensure a reasonable distance between the injection and production wells. The well inclination and total angle change rate 50m above the vertical depth of the horizontal section must meet the requirements of the combined displacement and venting process. The completion and sand control processes of the two rows of vertical wells and the one horizontal well must also meet the requirements of the combined displacement and venting process.

[0066] In one possible implementation, two rows of vertical wells are drilled in the upper part of the target oil reservoir, and one horizontal well is drilled at the bottom of the oil layer between the two rows of vertical wells. Vertically, the vertical error of the horizontal section trajectory from the target center does not exceed ±1.0m; horizontally, the error of the horizontal section trajectory from the target center does not exceed ±2.0m; the well inclination is less than 50° 50m above the vertical depth of the horizontal section; and the total angle variation rate is controlled within 3° / 25m. Figure 2 As shown. The horizontal well uses a three-stage completion method, 9 1 / 2 technical sleeve suspension 5 1 / 2 composite wire-wound screen completion, horizontal section open hole screen segment completion and segmented filling sand control, such as Figure 3 As shown; the two rows of vertical wells employ casing cementing and perforation completion and compression packing for sand control. The process proceeds to step 102.

[0067] Furthermore, in step 102, the two rows of vertical wells are perforated using cable delivery and near-balanced pressure to avoid contaminating the reservoir; considering steam over-coverage and vertical heterogeneity, the porosity is reduced at the top of the oil layer and the bottom where the physical properties are better to achieve a balanced steam intake profile and enhance the expansion of the steam chamber; perforation is carried out using an all-around spiral perforation method with tubing delivery.

[0068] In one possible implementation, cable delivery is used to perforate the three sections of the steam injection vertical well in the target block's venting composite well group at a near-surface equilibrium pressure of 11.5 MPa. A 127mm perforation gun is used, and the projectile types are selected based on the physical properties and water flooding degree of the three sections: 127mm deep penetration, 127mm BH, and 127mm enhanced perforation. The perforation density is 16–40 holes / m, with a 360° omnidirectional spiral perforation pattern. Perforation is carried out via tubing delivery. Specific perforation plans are shown in Table 1. The process then proceeds to step 103.

[0069] Table 1. Elastic performance parameters of the perforating gun for steam injection vertical wells in a certain block's combined expulsion and drainage well group.

[0070]

[0071] Furthermore, in step 103, a supercritical steam injection boiler is used to simultaneously inject steam into two rows of vertical wells and one horizontal well. The steam injection pressure is controlled within a range of 2-3 MPa higher than the formation fracturing pressure. The purpose is to generate several micro-fractures in the formation, which is conducive to achieving faster thermal connectivity between the injection and production wells. At the same time, increasing the steam injection intensity of the vertical and horizontal wells to twice that of conventional steam huff and puff can further accelerate the thermal connectivity between the injection and production wells.

[0072] In one possible implementation, after fracturing operation testing, the target reservoir formation fracturing pressure is 23.5 MPa. Two 23t 26MPa supercritical boilers are used to simultaneously inject steam into two rows of vertical wells and one horizontal well in the displacement-venting composite well group. The steam injection rate of each well is maintained at 4-5 t / h. The steam injection intensity of the vertical wells should reach about 200-250 t / m, which translates to a cycle injection volume of about 4000-5000 t. The steam injection intensity of the horizontal wells should reach about 15-20 t / m, which translates to a cycle injection volume of about 5000-6000 t. The entire displacement-venting composite well group injects a total of 33,000 t of steam in one cycle, taking about 30 days. The process then proceeds to step 104.

[0073] Furthermore, in step 104, the wells are kept steamed for a period of time to allow sufficient heat exchange between the injected steam and the reservoir. Then, each well simultaneously recovers the condensate produced after the injected steam and reservoir exchange heat. To shorten the preheating time, a higher fluid recovery intensity is used for recovery. When the cumulative recovered water volume reaches the water equivalent of the injected steam, the next round of micro-fracture high-intensity combined injection and production begins.

[0074] In one possible implementation, after simmering the well for 4-5 days, the well is simultaneously opened to recover the condensate. The fluid recovery rate for vertical wells is 120 t / d, and for horizontal wells it is 200 t / d. After approximately 40 days of recovery, the cumulative recovered water volume reaches the water equivalent of the injected steam, and the process transitions to the next round of micro-fracturing high-intensity combined injection and production, repeating steps 103 and 104. The process then proceeds to step 105.

[0075] Furthermore, in step 105, existing wells between vertical wells and between vertical and horizontal wells are used as observation wells to monitor the reservoir temperature, ensuring at least one observation well between each vertical and horizontal well. When the temperature monitored by all observation wells reaches the temperature required for the crude oil in the reservoir to transform into a Newtonian fluid, it indicates that good thermal connectivity has been achieved between the injection and production wells, and the process can proceed to the combined production stage of displacement and drainage.

[0076] In one possible implementation, six existing wells between the vertical and horizontal wells in the target area's combined well group for stabilization and drainage are used as temperature and pressure observation wells, such as... Figure 5 As shown. Meanwhile, based on the crude oil rheological curve of the target area, the temperature required for the crude oil to transform into a Newtonian fluid is 70℃. After two rounds of high-intensity combined injection and production using micro-fracturing in the two rows of vertical wells and one horizontal well in the combined displacement and venting well group, the temperatures monitored in the six observation wells all exceeded 70℃, indicating that full thermal connectivity had been achieved between the vertical and horizontal wells. At this point, the combined displacement and venting production stage can begin.

[0077] In conclusion:

[0078] Based on conventional injection preheating, this invention utilizes horizontal well drilling trajectory control and segmented completion technology, as well as vertical well variable density perforation, to maximize the uniform expansion of the steam chamber in both the plane and longitudinal direction. Simultaneously, through micro-fracture high-intensity synchronous steam injection and synchronous short-time recovery of condensate, rapid and uniform preheating between injection and production wells is achieved, thus providing a favorable guarantee for the success of the combined production stage of displacement and drainage.

[0079] The preheating method provided by this invention can shorten the preheating time by 50% and reduce the steam consumption by 80% compared with the existing SAGD steam injection cycle preheating, and the preheating uniformity is improved by nearly 25% compared with the steam-driven huff and puff preheating.

[0080] 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 deep heavy oil drive discharge composite rapid preheating method, characterized in that, The method comprises the following steps: Step 101: drilling several vertical wells in the upper part of the oil layer, and drilling a horizontal well at the bottom of the oil layer between the several vertical wells; Step 102: performing variable-density perforation on the vertical wells according to the longitudinal heterogeneity of the reservoir; Step 103: simultaneously injecting high-intensity steam into the vertical wells and the horizontal well at a pressure slightly higher than the formation fracture pressure; Step 104: after a period of soaking, starting the next round of high-intensity micro-fracturing steam injection after water drainage; Step 105: monitoring the temperature of the several vertical wells and between them and the horizontal well, and when the temperature exceeds the temperature required for the oil in the oil layer to become a Newtonian fluid, the preheating ends and enters the drainage and expulsion combined production stage; In the step 101, two rows of vertical wells are drilled in the upper part of the oil layer, and one horizontal well is drilled at the bottom of the oil layer between the two rows of vertical wells; In the step 101, the trajectory of the drilled horizontal well is ensured to be horizontal in the longitudinal direction; In the step 101, the horizontal segment trajectory on the horizontal well plane cannot deviate from the target center; the deviation and the full-angle change rate of the well inclination above the vertical depth of the horizontal segment meet the requirements of the drainage and expulsion combined process; In the step 103, a supercritical steam injection boiler is used to simultaneously inject steam into the vertical wells and the horizontal well; In the step 103, the steam injection pressure ranges from 2 to 3 MPa higher than the formation fracture pressure; In the step 103, the steam injection intensity of the vertical wells and the horizontal well is increased to twice that of conventional steam stimulation, further accelerating the heat connection between the injection and production wells; In the step 104, a period of soaking is performed to allow the injected steam and the reservoir to fully exchange heat, and then the condensate water generated after the exchange of heat between the injected steam and the reservoir is simultaneously recovered from each well; In the step 105, the old wells between the vertical wells and between the vertical wells and the horizontal well are used as observation wells to monitor the temperature of the oil layer, and at least one observation well is ensured between each vertical well and the horizontal well; In the step 105, when the temperature monitored by all the observation wells reaches the temperature required for the oil in the oil layer to become a Newtonian fluid, it indicates that good heat connection has been achieved between the injection and production wells, and the drainage and expulsion combined production stage is entered.

2. The method according to claim 1, wherein the method is characterized by: The completion and sand control processes of the vertical wells and the horizontal well also meet the requirements of the drainage and expulsion combination.

3. The method of claim 1, wherein the method is characterized by: In the step 102, the vertical wells are perforated by cable transmission and near-balanced pressure perforation.

4. The method of claim 1, wherein the method is characterized by: In the step 102, the hole density is reduced at the top of the oil layer and the bottom with better physical properties.

5. The method of claim 1, wherein the method is a deep heavy oil displacement and drainage composite rapid preheating method. In the step 102, the holes are arranged in all directions by spiral perforation, and the perforation is performed by tubing transmission.

6. The method of claim 1, wherein the method is a deep heavy oil displacement and drainage composite rapid preheating method. In the step 104, in order to shorten the preheating time, a higher liquid recovery intensity is used for recovery, and when the cumulative recovery water volume reaches the water equivalent of the injected steam, the next round of high-intensity combined injection and production is started.

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