Shale oil injection air huff and puff and electric heating well composite well oil extraction method
By setting up electric heating wells outside the air injection well network, the problem of uneven heating of the shale oil reservoir was solved, the efficient utilization of shale oil and the improvement of recovery rate were achieved, and the fluidity and permeability of the reservoir were enhanced.
Patent Information
- Application Number
- CN202410315277.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-03-19
- Publication Date
- 2025-09-19
AI Technical Summary
Shale oil reservoirs have low permeability and poor crude oil fluidity. Conventional water injection or gas injection methods are difficult to increase recovery rates, and the throughput well network cannot effectively heat the entire reservoir, resulting in a rapid decline in initial shale oil production and the crude oil in the reservoir is not effectively utilized.
Electric heating wells are set up outside the air injection well network. By rationally arranging the boundary electric heating wells, the formation heating rate and heating range are increased, and the oil production process is executed in combination with pressure information monitoring.
It has improved the effective utilization range and recovery rate of shale oil, increased the porosity and permeability of the reservoir, and improved the fluidity and production efficiency of shale oil.
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Figure CN120667075A_ABST
Abstract
Description
Technical Field
[0001] This article relates to the technical field of shale oil development, and in particular to a composite well production method for shale oil using air injection and electric heating wells. Background Art
[0002] Shale oil generally refers to oil resources enriched in organic-rich shale formations, and is also used to describe crude oil produced from other unconventional, extremely low-permeability shale formations.
[0003] The shale oil currently refers to liquid hydrocarbons that exist in effective hydrocarbon-generating shale formations in a free, dissolved and adsorbed state and can be directly obtained through drilling, fracturing and other means. Shale oil can be divided into two types: one is that the organic matter in the shale generates medium to heavy oil at a lower maturity stage, which is relatively enriched in the shale formation, has a relatively high viscosity and poor recoverability; the other is that the organic matter in the shale reaches a medium to high maturity stage, forming light oil or even condensate oil, which is enriched in the shale formation and has good recoverability.
[0004] Shale oil is mainly developed through a depletion-type development method that involves first performing horizontal well volume fracturing and then injecting gas or water. This can increase shale oil recovery rates within a certain range. However, due to the relatively well-developed micro- and nano-scale pore throats in shale oil reservoirs, the permeability of shale oil reservoirs is low, the fluidity of crude oil is low, and the scope of gas or water injection is also reduced. Conventional water injection is difficult to replenish energy, resulting in a rapid decline in initial shale oil production. A large amount of crude oil in the reservoir has not been effectively utilized, making it difficult to further increase crude oil recovery rates. Summary of the Invention
[0005] The present application provides a composite well production method for shale oil using air injection and electric heating wells. This method increases the rate of formation heating, improves the formation heating temperature and heating range, and increases the effective utilization range of shale oil by setting corresponding electric heating wells outside the original air injection and ventilation well network.
[0006] The present application provides a composite well oil production method for shale oil by air injection and electric heating, the method comprising:
[0007] Determine the target area and layer for screening, and determine the well pattern type to be used for air injection;
[0008] Arranging boundary electric heating wells according to the determined well pattern type and in combination with predetermined rules;
[0009] heating the electric heating well and monitoring the pressure information of the air injection well;
[0010] Execute the corresponding oil production process according to the pressure information.
[0011] Compared to related technologies, this application provides a shale oil production method that combines air injection and electrical heating wells. The method includes: identifying and screening target areas and horizons, and determining the well pattern type to be used for air injection and electrical heating; arranging boundary electrical heating wells based on the determined well pattern and predefined rules; heating the electrical heating wells and monitoring the pressure information of the air injection and electrical heating wells; and executing the corresponding production process based on the pressure information. By installing corresponding electrical heating wells outside the existing air injection and electrical heating well pattern, this application increases the rate of formation heating, improves the formation heating temperature and heating range, and expands the effective range of shale oil production.
[0012] Other features and advantages of the present application will be described in the following description, and in part will become apparent from the description, or will be understood by practicing the present application. Other advantages of the present application can be realized and obtained by the solutions described in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The accompanying drawings are used to provide an understanding of the technical solution of the present application and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the technical solution of the present application and do not constitute a limitation on the technical solution of the present application.
[0014] Figure 1 This is a flow chart of a composite well oil production method for shale oil with air injection and electric heating wells according to an embodiment of the present application;
[0015] Figure 2 A schematic diagram of a parallel row throughput electric heating well layout method in some exemplary embodiments;
[0016] Figure 3 A schematic diagram of a staggered throughput electric heating well layout method in some exemplary embodiments;
[0017] Figure 4 A schematic diagram of a five-point throughput electric heating well pattern layout method in some exemplary embodiments;
[0018] Figure 5 A schematic diagram of a seven-point throughput electric heating well pattern layout method in some exemplary embodiments;
[0019] Figure 6 Schematic diagram of a parallel row throughput well pattern in some exemplary embodiments;
[0020] Figure 7 Schematic diagram of a staggered throughput well pattern in some exemplary embodiments;
[0021] Figure 8 A schematic diagram of a five-point throughput pattern in some exemplary embodiments;
[0022] Figure 9A schematic diagram of a seven-point throughput pattern in some exemplary embodiments;
[0023] Figure 10 Schematic diagram of a parallel row throughput electric heating well pattern in some exemplary embodiments;
[0024] Figure 11 Schematic diagram of a staggered throughput electric heating well pattern in some exemplary embodiments;
[0025] Figure 12 A schematic diagram of a five-point throughput electric heating well pattern in some exemplary embodiments;
[0026] Figure 13 Schematic diagram of a seven-point electric heating well pattern in some exemplary embodiments. DETAILED DESCRIPTION
[0027] This application describes multiple embodiments, but this description is exemplary rather than restrictive, and it will be apparent to those skilled in the art that there may be more embodiments and implementations within the scope of the embodiments described herein. Although many possible feature combinations are shown in the drawings and discussed in the detailed description, many other combinations of the disclosed features are also possible. Unless specifically limited, any feature or element of any embodiment may be used in combination with any other feature or element in any other embodiment, or may replace any other feature or element in any other embodiment.
[0028] This application includes and contemplates combinations of features and elements known to those of ordinary skill in the art. The embodiments, features, and elements disclosed in this application may also be combined with any conventional features or elements to form a unique inventive solution defined by the claims. Any features or elements of any embodiment may also be combined with features or elements from other inventive solutions to form another unique inventive solution defined by the claims. Therefore, it should be understood that any feature shown and / or discussed in this application may be implemented individually or in any appropriate combination. Therefore, except for the limitations made according to the appended claims and their equivalents, the embodiments are not subject to other limitations. In addition, various modifications and changes may be made within the scope of protection of the appended claims.
[0029] In addition, when describing representative embodiments, the specification may have presented the method and / or process as a specific sequence of steps. However, to the extent that the method or process does not rely on the specific order of the steps described herein, the method or process should not be limited to the steps in the specific order described. As will be understood by those skilled in the art, other orders of steps are also possible. Therefore, the specific order of the steps set forth in the specification should not be interpreted as a limitation to the claims. In addition, the claims for the method and / or process should not be limited to performing their steps in the order written, and those skilled in the art can readily understand that these orders can be changed and still remain within the spirit and scope of the embodiments of the present application.
[0030] Shale oil generally refers to petroleum resources concentrated in organic-rich shale formations. It is also used to describe crude oil produced from other unconventional, low-permeability shale formations. Currently, shale oil refers to oil that occurs in free, dissolved, or adsorbed states within effective hydrocarbon-generating shale formations.
[0031] Air injection huff and puff development primarily consists of three phases: injection, well soaking, and recovery. During the injection phase, crude oil combustion near the wellbore generates heat and flue gas, which propagates and diffuses radially into the surrounding formations. During the well soaking phase, the crude oil continues to burn, consuming oxygen in the air cavity to the maximum extent possible while allowing non-condensable gases to continue diffusing and dissolving, transferring heat vertically. During the recovery phase, components resulting from thermal distillation and cracking are mixed with the original crude oil and flue gas and recovered. The air injection well is both an ignition well and an oil production well. After one air injection huff and puff cycle is completed, the next cycle of burning the oil layer can begin. Compared to steam huff and puff, air injection huff and puff eliminates heat loss from surface pipelines and wellbores, and can simultaneously form a multi-action mechanism of heat, steam, and flue gas.
[0032] Electric heating technology uses various techniques to transfer energy into the reservoir without injecting a heat transfer fluid, converting electrical energy into thermal energy, thereby achieving electrical heating of the reservoir. Based on the heating principle, the current main electric heating technologies for oil reservoirs can be divided into three categories: resistance heating, electromagnetic heating, and induction heating. Resistance heating and electromagnetic heating refer to heating through heat conduction and electromagnetic field oscillation, respectively, through a heating resistor. Electric heating wells are injection or production wells in which an electric heating device is placed in the wellbore, providing heating for both the wellbore and the formation.
[0033] In some throughput technologies, a lot of research focus has been on the throughput injection process and the relationship between injection and production. A large number of throughput wells are deployed on the basis of the original well network, with a small number of wells invested. In the absence of faults or other closed boundaries, efficient heating and rapid temperature increase of the formation cannot be achieved. In addition, the range of action of the throughput is a circular area. Under various well network conditions, there will be rock formations that are not reached by the throughput.
[0034] Therefore, in response to the problems existing in the above-mentioned technologies, the inventors proposed an oil production method based on the existing air injection and huff-and-puff well network, which increases the rate of formation heating, improves the formation heating temperature and heating range, and ultimately increases the effective utilization range of shale oil.
[0035] The embodiment of the present invention provides a composite well oil production method for shale oil by air injection and electric heating well, such as Figure 1 As shown, the method includes steps S100-S130:
[0036] S100: Determine the target area and layer for screening, and determine the well pattern type used for air injection;
[0037] S110: Arranging boundary electric heating wells according to the determined well pattern type and in combination with predetermined rules;
[0038] S120: Heating the electric heating well and monitoring pressure information of the air injection well;
[0039] S130: If the pressure information satisfies the production conditions, a corresponding oil production process is executed on the air injection huff and puff well.
[0040] In one exemplary embodiment, the well layout method refers to a method for controlling the location, spacing, arrangement, geometry, and grid structure of various wells. The air injection well pattern types include one or more of the following: parallel well patterns, staggered well patterns, five-spot well patterns, and seven-spot well patterns.
[0041] In an exemplary embodiment, the arrangement of boundary electric heating wells in accordance with predetermined rules includes:
[0042] Step 1. Determine the thermal boundary according to a predetermined rule;
[0043] Step 2. Arrange electric heating wells on the thermal boundary.
[0044] In an exemplary embodiment, the process of determining the thermal boundary is as follows:
[0045] Step 1. Determine the heating radius of the electric heating well according to the heat source heat transfer model; Figure 2-5 As shown, the thermal boundary can be further determined based on this heating radius.
[0046] Step 2: Determine the thermal boundary based on the determined heating radius.
[0047] In an exemplary embodiment, a heating well in a homogeneous infinite formation transfers heat to the surrounding formation through the wellbore (the heat source temperature is Ts, the original temperature is Ti, and the heat inflow rate is ), the heat conduction equation in the radial coordinate system can be expressed as:
[0048]
[0049] Where T is temperature, °C; r is the distance from the wellbore center, m; t is time, d; α is the thermal diffusivity of the formation, m 2 / d.
[0050] The temperature at each location in the formation under original conditions (initial conditions) is:
[0051] T| t＝0 =T r
[0052] Among them, T r is the original formation temperature, ℃.
[0053] For an infinite layer without boundaries, the temperature at infinity (external boundary condition) remains unchanged from the original layer temperature:
[0054] T| r→∞ =T r
[0055] For the heating well wall (internal boundary condition), heat is output to the formation at a constant heating power:
[0056]
[0057] Where q is the heat output to the formation per unit time and per unit wellbore length, J / (d*m); k is the thermal conductivity of the formation, J / (d*℃*m).
[0058] Therefore, the mathematical model of heat transfer in an infinite layer with a single heat source is:
[0059]
[0060] The line source solution is obtained through Boltzmann transform, and the heat source heat transfer model is determined as:
[0061]
[0062] According to the heat source superposition theory, the temperature rise at any point on the two-dimensional plane should be equal to the sum of the temperature rises caused by heat transfer from all heat sources, that is:
[0063]
[0064] So the temperature at any point in the formation is solved as:
[0065]
[0066] After determining the temperature of any point in the formation through the above formula, the heating range above this temperature value is determined.
[0067] In an exemplary embodiment, the arrangement of boundary electric heating wells according to the determined well pattern type and in combination with predetermined rules includes: if the determined well pattern type is a parallel row well pattern, determining that the thermal boundary corresponding to the well pattern type is a square; arranging electric heating wells at each corner of the thermal boundary of the square, such as Figure 2 The diagram shows a schematic diagram of a parallel row of throughput well patterns.
[0068] In an exemplary embodiment, the arrangement of boundary electric heating wells according to the determined well pattern type and a predetermined rule includes: if the determined well pattern type is a staggered well pattern, determining that the thermal boundary corresponding to the well pattern type is a pentagon; and arranging electric heating wells at each corner of the thermal boundary of the pentagon. Figure 4 As shown in the figure, it is a schematic diagram of the staggered throughput well pattern.
[0069] In an exemplary embodiment, the arrangement of boundary electric heating wells according to the determined well pattern type and a predetermined rule includes: if the determined well pattern type is a five-point well pattern, determining that the thermal boundary corresponding to the well pattern type is a diamond; and arranging electric heating wells at each corner of the diamond-shaped thermal boundary. Figure 5 The diagram shows a five-point throughput well pattern.
[0070] In an exemplary embodiment, the boundary electric heating wells are arranged according to the determined well network type and in combination with predetermined rules, including: if the determined well network type is a seven-point well network, determining that the thermal boundary corresponding to the well network type is a hexagon; and arranging the electric heating wells at each corner of the thermal boundary of the hexagon. Figure 6 This is a schematic diagram of a seven-point throughput well pattern.
[0071] In one exemplary embodiment, executing a corresponding oil production process for an air huff and puff well includes: ceasing air injection into the air huff and puff well and initiating well shutoff; and upon detecting an increase in the wellhead pressure of the air huff and puff well, opening the well for oil production. In this embodiment, when the wellhead pressure rises to 2.0 times the hydrostatic pressure, air injection is ceased and well shutoff is initiated. When the wellhead pressure suddenly rises, the well is opened for flowing production. In this embodiment, the pressure of the huff and puff well can be determined based on actual conditions.
[0072] This embodiment, through reasonable step design, first screens the areas and layers suitable for air injection and huff and puff development, and innovatively proposes a composite well production method and steps for shale oil air injection and huff and puff and electric heating wells; proposes a composite well layout method for shale oil air injection and huff and puff and electric heating wells in different well patterns; in a common huff and puff well pattern, through the well pattern densification form, electric heating vertical wells are set as thermal boundaries in the well pattern gaps, so that the heat transfer range of the central heating well is reduced, thereby reducing the heat loss to the peripheral formations during the rapid heating stage of the central area, so that the target formation is heated efficiently and quickly, the formation heating rate is increased, the formation heating range is improved, the reservoirs that are not reached by the huff and puff are fully utilized, and the effective utilization range of shale oil is increased.
[0073] Example 1
[0074] For a certain target area, the specific implementation process of using the above-mentioned shale oil air injection and electric heating well composite well production method for oil production is as follows:
[0075] The first step is to screen the target area and layer and determine the well pattern type to be used for air injection.
[0076] The types of well patterns used for air injection include: parallel well pattern, staggered well pattern, five-point well pattern and seven-point well pattern. Generally, the well spacing of air injection well pattern is 100-125m, and the effective radius of air injection is 50m. Figure 6-9 As shown, Figure 6 This is a schematic diagram of a parallel row of throughput well patterns, with the middle area being the unused area. Figure 7 This is a schematic diagram of a staggered throughput well pattern, with the middle area being the unused area. Figure 8 This is a schematic diagram of a five-point throughput well pattern, with the middle area being the unused area. Figure 9 This is a schematic diagram of a seven-point throughput well pattern, with the middle area being the unused area.
[0077] The second step is to drill a vertical well from the surface through the shale oil reservoir and complete the well using perforation completion;
[0078] Step 3: Arrange boundary electric heating wells according to the determined well pattern type and predetermined rules;
[0079] Depending on the well pattern type used, there may be unused areas in the air injection huff-and-puff pattern, such as Figure 6-9 The black circle indicates that the unused area is generally small, with a diameter of less than 10m, which is not enough to drill another air injection well. However, the electric heating well has a mature technology and an effective range of less than 10m. Deploying electric heating wells in the unused area can effectively increase the production range. Figure 6-9 Drill electric heating wells within the range shown (the effective radius of electric heating is 5 to 10 meters). The specific layout is as follows Figure 10-13As shown;
[0080] Step 4: Hydraulic fracturing is performed on the huff-and-puff well to form a fracture network in the formation with a half-length of 40 to 50 meters. High-temperature resistant proppants are added to significantly improve the air injection capacity during the ignition phase of the air injection huff-and-puff process.
[0081] Step 5: Start the electric heating well to heat and monitor the temperature and pressure increase;
[0082] Step 6: Start ignition and inject air to maintain the high-temperature oxidation combustion state of the formation;
[0083] Step 7: When the pressure of the huff and puff well rises to 2.0 times of the hydrostatic pressure, stop injecting air and start to shut down the well. When the pressure at the huff and puff wellhead suddenly rises, start the well to start flowing production.
[0084] Compared with current shale oil development methods, the composite shale oil production method using air injection and electric heating wells proposed in this invention has the following advantages:
[0085] 1. In the common throughput well pattern, through the well pattern densification, electric heating vertical wells are set in the well pattern gaps as thermal boundaries. Figure 2-5 , which reduces the heat transfer range of the central heating well, thereby reducing the heat loss to the peripheral formations during the rapid heating stage of the central area, so that the target formation can be heated efficiently and quickly.
[0086] 2. The range of the throughput is a circular area. Under various well pattern conditions, there will be reservoirs that are not affected by the throughput. By installing electric heating wells in the gaps between the throughput well patterns, the speed of formation heating can be increased. Figure 2 As shown in the figure, the temperature of the four throughput centers reaches 400-500 degrees. From the center of the throughput well to the edge of the throughput well, the temperature drops from 400-500 degrees to over 100 degrees. The edge of the throughput well at over 100 degrees does not reach the temperature range of in-situ conversion and viscosity reduction, and the crude oil cannot be effectively used. If we add electric heating wells at appropriate locations, it will form Figure 2 The thermal boundary shown has the effect of heat preservation. Then, through limited heat, the edge of the wellbore, which was originally only more than 100 degrees, can be quickly raised to 300 to 400 degrees, which significantly increases the effective utilization range of shale oil. Figure 3 、 Figure 4 , Figure 5 It can be proved that the range of formation heating has been improved and the effective utilization range of shale oil has been increased.
[0087] 3. By injecting air, the fluidity of shale crude oil and the porosity and permeability of the reservoir are improved, so that the fluidity of shale oil is increased, the porosity of the reservoir is expanded, and the permeability is improved, so that the effective utilization range of shale oil in the reservoir is significantly improved.
[0088] It will be appreciated by those skilled in the art that all or some of the steps, systems, and functional modules / units in the methods disclosed above may be implemented as software, firmware, hardware, and appropriate combinations thereof. In hardware implementations, the division between the functional modules / units mentioned in the above description does not necessarily correspond to the division of physical components; for example, a physical component may have multiple functions, or a function or step may be performed by several physical components in cooperation. Some or all components may be implemented as software executed by a processor, such as a digital signal processor or a microprocessor, or implemented as hardware, or implemented as an integrated circuit, such as an application-specific integrated circuit. Such software may be distributed on a computer-readable medium, which may include a computer storage medium (or non-transitory medium) and a communication medium (or temporary medium). As is well known to those skilled in the art, the term computer storage medium includes volatile and non-volatile, removable, and non-removable media implemented in any method or technology for storing information (such as computer-readable instructions, data structures, program modules, or other data). Computer storage media include, but are not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disks (DVD) or other optical disk storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to store the desired information and can be accessed by a computer. In addition, it is well known to those skilled in the art that communication media generally embodies computer-readable instructions, data structures, program modules, or other data in a modulated data signal such as a carrier wave or other transport mechanism, and may include any information delivery media.
Claims
1. A composite well oil production method for shale oil by air injection and electric heating wells, characterized in that: The method comprises: Determine the target area and layer for screening, and determine the well pattern type for air injection wells; Arranging boundary electric heating wells according to the determined well pattern type and in combination with predetermined rules; heating the electric heating well and monitoring the pressure information of the air injection well; If the pressure information satisfies the production conditions, a corresponding oil production process is executed on the air injection well.
2. The shale oil air injection and electric heating well composite well oil production method according to claim 1 is characterized in that: The well pattern types of the air injection huff-and-puff wells include one or more of the following: a parallel row well pattern, a staggered row well pattern, a five-spot well pattern, and a seven-spot well pattern.
3. The shale oil air injection and electric heating well composite well oil production method according to claim 1 is characterized in that: The arrangement of boundary electric heating wells in accordance with predetermined rules includes: Determining thermal boundaries according to predetermined rules; An electrical heating well is arranged on the thermal boundary.
4. The shale oil air injection and electric heating well composite well oil production method according to claim 3 is characterized in that: The process of determining the thermal boundary is as follows: Determine the heating radius of the electric heating well based on the heat source heat transfer model; The thermal boundary is determined based on the determined heating radius.
5. The shale oil air injection and electric heating well composite well oil production method according to claim 4 is characterized in that: The heat source heat transfer model is: In the above formula, T is the temperature at different times at a distance r from the wellbore, T r is the original formation temperature at a distance r from the wellbore, q is the heat output to the formation per unit time and per unit wellbore length, k is the formation thermal conductivity, Ei is the power integral function, r is the distance from the wellbore center, t is the time, and α is the thermal diffusivity of the formation.
6. The shale oil air injection and electric heating well composite well oil production method according to claim 2 is characterized in that: The step of arranging boundary electric heating wells according to the determined well pattern type and in combination with predetermined rules includes: If the determined well pattern type is a parallel row well pattern, the thermal boundary corresponding to the well pattern type is determined to be a square; Electrically heated wells are arranged at each corner of the thermal boundary of the square.
7. The shale oil air injection and electric heating well composite well oil production method according to claim 2, characterized in that: The step of arranging boundary electric heating wells according to the determined well pattern type and in combination with predetermined rules includes: If the determined well pattern type is a staggered well pattern, the thermal boundary corresponding to the well pattern type is determined to be a pentagon; Electrically heated wells are arranged at each corner of the thermal boundary of the pentagon.
8. The shale oil air injection and electric heating well composite well oil production method according to claim 2, characterized in that: The step of arranging boundary electric heating wells according to the determined well pattern type and in combination with predetermined rules includes: If the determined well pattern type is a five-point well pattern, the thermal boundary corresponding to the well pattern type is determined to be a diamond shape; An electric heating well is arranged at each corner of the diamond-shaped thermal boundary.
9. The shale oil air injection and electric heating well composite well oil production method according to claim 2, characterized in that: The step of arranging boundary electric heating wells according to the determined well pattern type and in combination with predetermined rules includes: If the determined well pattern type is a seven-point well pattern, the thermal boundary corresponding to the well pattern type is determined to be a hexagon; Electrically heated wells are arranged at each corner of the hexagonal thermal boundary.
10. The shale oil air injection and electric heating well composite oil production method according to claim 1, wherein the corresponding oil production process is performed on the air injection and electric heating well, comprising: Stop injecting air into the air injection well and start soaking the well; When it is monitored that the wellhead pressure of the air injection well increases, the well is opened to produce oil.