An oil displacement method for high-dip heavy oil reservoirs

Abstract

The present disclosure provides a method for displacing oil in a high-dip heavy oil reservoir, which relates to the technical field of oil and gas resource development. The method includes: determining the distribution characteristics and types of remaining oil in a well based on the three-dimensional geological data and production data of the well; plugging the steam drive channeling channels using a gel profile control agent based on the distribution characteristics and types of the remaining oil; stripping the crude oil on the surface of the pores and pore throats in the well after plugging using an imbibition agent; displacing the remaining oil in the microscopic reservoir space in the well after stripping based on the in-situ chemical heat treatment technology for plug removal; assisting in displacing the remaining oil in the well after displacement based on the steam drive slug technology; and the steam drive slug technology consists of multiple functional slugs. The method for displacing oil in a high-dip heavy oil reservoir of the present disclosure can improve the oil recovery rate of the high-dip heavy oil reservoir.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas resource development, and in particular to an oil displacement method for high-inclination heavy oil reservoirs. Background Art

[0002] In the field of heavy oil thermal recovery, steam injection technology is the mainstream development method, accounting for more than 90% of the global heavy oil production. Among them, steam injection technology includes steam stimulation, steam drive and steam assisted gravity drainage (SAGD, Steam Assisted Gravity Drainage). However, in the process of steam injection development, steam channeling is generally faced with the problem of steam channeling, and its causes mainly include two categories: one is that high-pressure steam injection causes the expansion of natural fractures in the reservoir or induces new fractures; the other is that the reservoir is significantly heterogeneous (such as large permeability differences, uneven interlayer development, etc.), causing steam to preferentially form a "high-speed channel" along the high-permeability zone or fracture to rush to the adjacent well, resulting in ineffective dissipation of heat energy, limited reservoir swept volume, and ultimately a significant reduction in recovery.

[0003] At present, steam crossflow is mainly controlled through mechanical plugging and chemical plugging. Mechanical plugging relies on downhole tools (such as packers) to physically isolate the crossflow layer, but it has limitations such as complex construction, poor adaptability and short validity period. Chemical plugging is centered on plugging agents such as smart gels and temperature-resistant particles. After being injected into the formation, they preferentially enter the high-permeability channel, and effectively block the steam crossflow path through physical plugging, chemical adsorption and film-forming isolation in the pores, forcing subsequent steam to turn to low-permeability unused areas, realizing deep reservoir regulation and drive. It has the advantages of low cost and strong adaptability, and significantly improves the thermal recovery sweep coefficient.

[0004] However, there is no ideal method for further improving the recovery rate in the later stage of steam injection development, especially the recovery rate of high-inclination heavy oil reservoirs. Summary of the invention

[0005] The present disclosure provides an oil displacement method for a high-inclination heavy oil reservoir, so as to at least solve the above technical problems existing in the prior art.

[0006] According to a first aspect of the present disclosure, a method for displacing oil in a high-dip heavy oil reservoir is provided, including: determining the distribution characteristics and types of remaining oil in an oil well based on the three-dimensional geological data and production data of the oil well; the three-dimensional geological data includes the structural dip angle of the oil well, the fault development characteristics, and the reservoir heterogeneity data, and the production data includes the logging data, the rock physical property data, the pressure data, the production performance curve, and the production data of the oil well; based on the distribution characteristics and types of the remaining oil, using a gel profile control agent to plug the steam drive channeling channels; based on the imbibition agent to strip the crude oil on the surface of the pores and pore throats in the oil well after plugging; based on the in-situ chemical heat treatment technology in the layer to displace the remaining oil in the microscopic reservoir space in the oil well after stripping; based on the steam drive slug technology to assist in displacing the remaining oil in the oil well after displacement; the steam drive slug technology is composed of multiple functional slugs.

[0007] In an implementable embodiment, the determining the distribution characteristics and types of remaining oil in the oil well based on the three-dimensional geological data and production data of the oil well includes: determining the areas where remaining oil may exist based on the three-dimensional geological data through the layer system division method and the sedimentary facies analysis method, and determining the distribution characteristics of the remaining oil based on the areas where remaining oil may exist; determining the types of the remaining oil based on the production data and the distribution characteristics through the numerical simulation method and the physical simulation method; the production data is all the data collected during the full life cycle of the oil well, and the production data includes at least one of the oil well attribute data and the oil well operation data.

[0008] In an implementable embodiment, the types of the remaining oil include macroscopic remaining oil and microscopic remaining oil, the macroscopic remaining oil includes unwell-controlled remaining oil and well-controlled remaining oil, and the microscopic remaining oil includes adsorbed remaining oil and shielded remaining oil.

[0009] In an implementable embodiment, the fault development characteristics include at least one of lithology and sedimentary characteristics, porosity and permeability characteristics, structure and fracture development, thermophysical properties, and fluid and pressure characteristics; the oil well attribute data includes at least one of logging data, rock physical property data, geophysical and geological data, completion data, and reservoir fluid property data; the oil well operation data includes at least one of pressure data, production performance curve, reservoir dynamic response data, and production data.

[0010] In one feasible embodiment, plugging the steam drive channeling channels using a gel profile control agent based on the distribution characteristics and types of the remaining oil includes: determining the steam drive channeling channels based on the distribution characteristics and types of the remaining oil; the steam drive channeling channels include at least one of high permeability layers, natural fractures, and channels formed by long-term water injection; plugging the steam drive channeling channels based on the gel profile control agent; the gel profile control agent is based on an inorganic polymer and forms a plugging body with a gel structure through the reaction of an ammonia-based coagulant and a stabilizer.

[0011] In one feasible embodiment, the ammonia-based coagulant is a coagulant mainly composed of an organic compound containing an amino group or an amine group.

[0012] In one feasible embodiment, the imbibition agent is a small molecule aggregate formed with a nano-core as the core and a short-chain imbibition agent as the shell; the diameter of the nano-core is 7 - 8 nm.

[0013] In one feasible embodiment, the in-situ chemical heat treatment technology for plugging removal injects a target chemical agent into the formation of an oil well, and displaces the remaining oil in the microscopic reservoir space of the oil well after stripping based on the heat, gas, and foam generated by the chemical reaction of the target chemical agent in the formation.

[0014] In one feasible embodiment, the target chemical agent includes at least one of dimethyl fumarate and chitosan, a foaming agent, and a sheet-like nano foam stabilizer constructed by the double-fluid method; the foaming agent is a surfactant capable of forming stable foam in a liquid, and the foaming agent is an anionic surfactant; the sheet-like nano foam stabilizer is a functional material with a nano-scale sheet structure.

[0015] In one feasible embodiment, the auxiliary displacement of the remaining oil in the oil well after displacement based on the steam drive slug technology includes: based on the test slug technology, injecting clear water or oilfield water into the target formation in the oil well, and determining the liquid absorption capacity and permeability characteristics of the formation, as well as the distribution of high permeability channels and low permeability regions through the pressure changes, flow rate data, and formation liquid absorption rate during the injection process; based on the plugging slug technology, using gel particles as a channel plugging agent to plug the high permeability channels; based on the imbibition slug technology, injecting a surfactant imbibition agent into the oil well, and using the capillary force to penetrate into the low permeability regions to strip the remaining oil on the rock surface to form an emulsion flow; based on the self-generated gas foam slug, using a self-generated gas foam system to generate gas through a chemical reaction to form foam, displace the pore crude oil, and turn the displacement fluid multiple times; based on the displacement fluid slug, using clear water or oilfield water to push the chemical agent into the formation to form an isolation zone, so that the chemical agent can fully contact and react with the crude oil.

[0016] A method for displacing oil in a high-dip heavy oil reservoir according to the present disclosure determines the distribution characteristics and types of remaining oil in a well based on the three-dimensional geological data and production data of the well, and plugs the steam drive channeling channels using a gel profile control agent based on the distribution characteristics and types of the remaining oil. Then, based on the imbibition agent, the crude oil on the surfaces of the pores and pore throats in the well after plugging is stripped, and based on the in-situ chemical heat treatment technology in the formation, the remaining oil in the microscopic reservoir space in the well after stripping is displaced. Finally, based on the steam drive slug technology, the remaining oil in the well after displacement is assisted in displacement, and the steam drive slug technology consists of multiple functional slugs. Thus, the present disclosure comprehensively utilizes different technical means and chemical agents under the assistance of gravity to displace different types of remaining oil, and can improve the oil recovery rate of the high-dip heavy oil reservoir.

[0017] It should be understood that the content described in this part is not intended to identify the key or important features of the embodiments of the present disclosure, nor is it used to limit the scope of the present disclosure. Other features of the present disclosure will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] By referring to the drawings and reading the detailed description below, the above and other objects, features, and advantages of the exemplary embodiments of the present disclosure will become easily understood. In the drawings, several embodiments of the present disclosure are shown in an exemplary rather than restrictive manner, where:

[0019] In the drawings, the same or corresponding reference numerals represent the same or corresponding parts.

[0020] Figure 1 The flowchart of a method for displacing oil in a high-dip heavy oil reservoir according to an embodiment of the present disclosure is shown Figure 1 ;

[0021] Figure 2 The flowchart of a method for displacing oil in a high-dip heavy oil reservoir according to an embodiment of the present disclosure is shown Figure 2 . DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] To make the objectives, features, and advantages of the present disclosure more obvious and understandable, the technical solutions in the embodiments of the present disclosure will be clearly and completely described below with reference to the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, rather than all the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of the present disclosure.

[0023] Figure 1 The flowchart of a method for displacing oil in a high-dip heavy oil reservoir according to an embodiment of the present disclosure is shown Figure 1 , as Figure 1As shown in the figure, a method for displacing oil in a high-dip heavy oil reservoir includes:

[0024] Step S101: Based on the three-dimensional geological data and production data of the oil well, determine the distribution characteristics and types of remaining oil in the oil well.

[0025] In this embodiment, first collect the three-dimensional geological data of the oil well, such as data on structural dip, fault development characteristics, and reservoir heterogeneity. The oil well can store a high-dip heavy oil reservoir. The three-dimensional geological data can reflect the overall structure and characteristics of the oil reservoir in the oil well. The three-dimensional geological data, that is, the single-well geological model, refers to the oil reservoir geological model established by using three-dimensional geological modeling on the basis of fine oil reservoir analysis, or the oil reservoir geological concept established by using other methods. At the same time, collect the production data of the oil well, including well logging data, rock physical property data, pressure data, production dynamic curves, production data, etc. The production data can reflect the attributes of the oil well and its dynamic performance during the production process. Through comprehensive analysis of the three-dimensional geological data and production data of the oil well, the distribution characteristics and types of remaining oil in the oil well can be determined.

[0026] Step S102: Based on the distribution characteristics and types of remaining oil, use a gel profile control agent to block the steam drive channeling channels.

[0027] In this embodiment, steam drive channeling mainly refers to the process in which the injected steam during steam drive does not uniformly displace the crude oil, but rapidly advances along the high-permeability channels in the formation, resulting in the premature breakthrough of steam to the production well and destroying the displacement balance. Among them, the high-permeability channels can be high-permeability layers, natural fractures, and channels formed by long-term water injection, etc. According to the determined distribution characteristics and types of remaining oil, the positions where channeling channels are likely to form during the steam drive process, that is, the positions of the high-permeability channels, can be identified. Then, a gel profile control agent can be used to block the steam drive channeling channels, so that the subsequent injected functional agents and steam can enter other channels to displace the physical property remaining oil and process remaining oil in the macroscopic remaining oil, and improve the oil recovery rate.

[0028] Step S103: Based on the imbibition agent, strip the crude oil on the surface of the pores and pore throats in the blocked oil well.

[0029] In this embodiment, after blocking the channels, an imbibition agent can be injected into the oil well. The imbibition agent can penetrate into the micro pores and pore throats of the oil reservoir and exert a stripping effect on the crude oil adsorbed on the surface of the micro pores and pore throats, liberating the crude oil from the adsorbed state, thereby increasing the recoverable crude oil volume.

[0030] Step S104: Based on the in-situ chemical heat treatment technology for plugging removal in the layer, displace the remaining oil in the microscopic reservoir space in the stripped oil well.

[0031] In this embodiment, the in-situ chemical pyrolysis plugging removal technology in the layer can be used. By utilizing the generated heat, gas, foam, etc., it can enter the microscopic reservoir spaces that could not be accessed by the previous steam flooding, displace the remaining oil inside the microscopic reservoir spaces, and be produced along with the subsequent oil displacement process, thereby improving the oil recovery rate.

[0032] Step S105: Based on the steam flooding slug technology, assist in displacing the remaining oil in the oil well after displacement.

[0033] In this embodiment, the steam flooding slug technology consists of multiple functional slugs. The multiple functional slugs include a test slug, a plugging slug, an imbibition slug, a self-generating gas foam slug, a displacement fluid slug, etc. The steam flooding slug technology can utilize the thermal wave effect generated by high temperature and high pressure to further expand the swept area of oil displacement. Through the synergistic effect of multiple functional slugs, the activated residual oil originally dispersed in the fine pores can be mobilized and advanced towards the production well area, ultimately achieving the goal of increasing the oil production of the oil well.

[0034] In another embodiment, step S101, "Based on the three-dimensional geological data and production data of the oil well, determine the distribution characteristics and types of the remaining oil in the oil well", includes:

[0035] Based on the three-dimensional geological data, through the layer series division method and sedimentary facies analysis method, determine the areas where remaining oil may exist, and based on the areas where remaining oil may exist, determine the distribution characteristics of the remaining oil; the three-dimensional geological data includes the structural dip angle of the oil well, fault development characteristics, and reservoir heterogeneity data;

[0036] Based on the production data and distribution characteristics, through numerical simulation methods and physical simulation methods, determine the types of the remaining oil; the production data is all the data collected during the entire life cycle of the oil well, and the production data includes oil well attribute data and oil well operation data.

[0037] In this embodiment, based on the three-dimensional geological data of the oil well, through the layer series division method and sedimentary facies analysis method, the oil reservoir can be finely described. Focus on analyzing the distribution laws of high-permeability strips and preferential flow channels, and determine the range of areas where remaining oil may exist in the oil well. The areas where remaining oil may exist usually have certain geological characteristics, such as changes in reservoir physical properties, fault development, etc. Through further research on these areas, the distribution characteristics of the remaining oil can be clarified. For example, in a high-dip angle oil reservoir, affected by the gravity effect, the remaining oil may be enriched in certain specific parts. For example, during the steam flooding process, due to the gravity segregation effect, the remaining oil may be relatively enriched in the upper or lower areas of the steam flooding front.

[0038] In this embodiment, it is also possible to combine the three-dimensional geological data, production data of the oil well, and the determined remaining oil distribution characteristics, and based on numerical simulation methods and physical simulation methods, determine the types of remaining oil. Among them, the numerical simulation method mainly refers to establishing a mathematical model of the reservoir and oil well by using the three-dimensional geological modeling method based on the geological model; the physical simulation method mainly refers to designing and processing a physical model that can reflect the actual characteristics of the target reservoir and oil well under the constraint of similarity criteria based on the geological model, and carrying out experimental simulation work based on this physical model. Through numerical simulation, physical and chemical processes such as fluid flow and heat transfer during the reservoir exploitation process can be simulated, and the production status of remaining oil in different regions can be analyzed; at the same time, by carrying out physical simulation experiments, a physical model of the reservoir can be constructed using similar materials, and the distribution pattern and types of remaining oil can be intuitively observed. By integrating the results of numerical simulation and physical simulation, the specific types of remaining oil can be determined.

[0039] In an implementable manner, the types of remaining oil include macroscopic remaining oil and microscopic remaining oil. Macroscopic remaining oil includes unwell-controlled remaining oil and well-controlled remaining oil. Microscopic remaining oil includes adsorbed remaining oil and shielded remaining oil. Among them, the unwell-controlled remaining oil in macroscopic remaining oil refers to the crude oil in some areas that has not been effectively exploited during the reservoir development process due to imperfect well pattern deployment, and some areas are not covered by the well control system; the well-controlled remaining oil refers to the crude oil that has not been produced within the well control range due to reasons such as reservoir heterogeneity and injection-production imbalance. The adsorbed remaining oil in microscopic remaining oil mainly refers to the heavy components in the crude oil that are adsorbed on the rock surface and are difficult to be produced by conventional oil displacement methods; the shielded remaining oil is the crude oil that is shielded and cannot contact the displacing agent due to certain geological structures or fluid flow characteristics in the reservoir. The types of remaining oil can provide accurate guidance for subsequent targeted oil displacement measures.

[0040] In another implementable manner, the fault development characteristics include at least one of lithology and sedimentation characteristics, porosity and permeability characteristics, structure and fracture development, thermophysical properties, and fluid and pressure characteristics. The fault development characteristics are mainly reflected in the reservoir characteristics of the oil well considering reservoir heterogeneity. Among them, lithology and sedimentation characteristics help to understand the formation and evolution process of the reservoir, and reservoirs with different lithologies have different oil storage capacities and seepage characteristics; porosity and permeability characteristics are directly related to the fluid flow ability in the reservoir and are one of the key factors affecting the remaining oil distribution; the structure and fracture development affect the overall structure of the reservoir and the fluid flow channels; thermophysical properties have an important impact on the heat conduction and distribution during the thermal recovery process of the reservoir; fluid and pressure characteristics reflect the state of the fluid and the pressure system in the reservoir. These characteristics are all closely related to fault development. Faults may provide preferential channels for fluid flow or may hinder fluid flow due to the presence of substances such as fault gouge.

[0041] In another feasible embodiment, the oil well attribute data includes at least one of well logging data, petrophysical data, geophysical and geological data, completion data, and reservoir fluid property data. The oil well attribute data is the static data of the oil well. Among them, the well logging data can provide geological information of the oil reservoir, such as the resistivity and porosity of the formation; the petrophysical data reflects the physical properties of the rock, such as particle size and sorting degree, which affect the oil storage and seepage capacity of the reservoir; the geophysical and geological data covers information on the structure, lithology, paleogeography, etc. of the oil reservoir; the completion data involves the completion method of the oil well, perforation intervals, etc., which affect the production performance of the oil well; the reservoir fluid property data includes the viscosity and density of crude oil, the solubility of natural gas, etc.

[0042] In another feasible embodiment, the oil well operation data includes at least one of pressure data, production performance curve, reservoir dynamic response data, and production rate data. The oil well operation data is the dynamic data of the oil well. Among them, the pressure data reflects the pressure change of the oil reservoir, which is of great significance for judging the driving mechanism and energy status of the oil reservoir; the production performance curve intuitively shows the change trend of the oil well production rate over time, which helps to analyze the exploitation effect of the oil reservoir; the reservoir dynamic response data can reflect the change of seepage characteristics of the oil reservoir during the development process; the production rate data is a direct indicator to measure the development benefit of the oil reservoir. Through comprehensive analysis of these oil well operation data, the production status of the oil reservoir and the dynamic change of the remaining oil distribution can be comprehensively understood.

[0043] In another embodiment, step S102, "Based on the distribution characteristics and types of remaining oil, use a gel profile control agent to plug the steam drive channeling channels", includes:

[0044] Based on the distribution characteristics and types of remaining oil, determine the steam drive channeling channels; the steam drive channeling channels include at least one of high-permeability layers, natural fractures, and channels formed by long-term water injection;

[0045] Based on the gel profile control agent, plug the steam drive channeling channels; the gel profile control agent is based on inorganic polymers and forms a plugging body with a gel structure through the reaction of ammonia-based coagulants and stabilizers.

[0046] In this embodiment, based on the determined remaining oil distribution characteristics and types, the positions in the reservoir where steam drive channeling may occur can be further analyzed. Steam drive channeling paths usually include high-permeability layers, natural fractures, and channels formed by long-term water injection, etc. For example, in the reservoir, there are high-permeability intervals. During the steam injection process, steam will preferentially flow rapidly along these high-permeability layers, forming preferential flow channels, resulting in local overheating and steam breakthrough. Natural fractures also provide paths for the rapid channeling of steam. Similarly, the channels formed by long-term water injection may also become the steam channeling paths during the steam drive process, affecting the oil displacement efficiency. Through the comprehensive analysis of the remaining oil distribution and reservoir geological characteristics, these steam drive channeling paths can be accurately located, thus providing a clear target for subsequent plugging measures.

[0047] In this embodiment, the steam drive channeling paths can be plugged based on the gel profile control agent. The gel profile control agent is based on inorganic polymers and forms a gel-structured plugging body through the reaction of ammonia-based coagulants and stabilizers. This gel profile control agent has good temperature and salt resistance properties, relatively high plugging strength, and is easy to degrade, without causing damage to the reservoir. During the implementation process, the gel profile control agent is injected into the area where the steam drive channeling paths are located. With the action of the gel profile control agent and formation conditions (such as temperature, pressure, etc.), a gel-structured plugging body is rapidly formed under the promotion of the ammonia-based coagulant, effectively plugging the high-permeability channels, natural fractures and other channeling paths, enabling the subsequent injected functional chemical slug and steam to enter other untouched or inefficiently exploited reservoir areas evenly, improving the swept volume of oil displacement and enhancing the recovery factor.

[0048] In an implementable manner, the ammonia-based coagulant is a coagulant mainly composed of organic compounds containing amino ( ) or amine groups ( ). These organic compounds can undergo chemical reactions with inorganic polymers and other additives, accelerating the gelation process of the gel profile control agent under formation conditions. For example, certain amine compounds can combine with the active groups in the inorganic polymer, promoting the occurrence of cross-linking reactions, enabling the gel profile control agent to form a gel structure with sufficient strength and stability in a relatively short time, thus effectively plugging the steam drive channeling paths. By selecting a suitable ammonia-based coagulant, the gelation time of the gel profile control agent can be adjusted to adapt to the geological conditions and construction requirements of different reservoirs, ensuring the timeliness and effectiveness of the plugging effect.

[0049] In an implementable manner, a stabilizer is a type of substance that can inhibit or slow down the structural damage, component decomposition or performance deterioration of substances (such as solutions, colloids, polymers, composite materials, etc.) caused by external factors (such as temperature, humidity, chemical action, mechanical stress, etc.). In the present disclosure, in order to ensure that the gel profile control agent can still maintain good basic properties after being injected into the formation, a stabilizer needs to be added to the gel profile control agent.

[0050] In one feasible embodiment, the imbibition agent in step S103 is a small molecule aggregate formed with a nano-core as the core and short-chain imbibition agents as the shell; the diameter of the nano-core is 7 - 8 nm. The small molecule aggregate can easily penetrate into the tiny pores and pore throats of the reservoir rock. After the imbibition agent enters these tiny pores and pore throats, the short-chain imbibition agents on its shell can strip the crude oil adsorbed on the surfaces of the pores and pore throats, reducing the adsorption force between the crude oil and the rock surface. At the same time, this type of imbibition agent usually also has the function of reducing the interfacial tension between oil and water, which helps to improve the fluidity of the crude oil, enabling the originally difficult-to-produce crude oil to be effectively mobilized and produced in the subsequent oil displacement process, thereby increasing the oil recovery rate.

[0051] In one feasible embodiment, the in-situ chemical pyrolysis plugging removal technology in step S104 refers to injecting a target chemical agent into the formation of an oil well, and based on the heat, gas (such as , etc.) and foam generated by the chemical reaction of the target chemical agent in the formation to displace the remaining oil in the microscopic reservoir space in the oil well after stripping. Among them, the heat generated by the chemical reaction can increase the formation temperature and reduce the viscosity of the crude oil. At the same time, the expansion effect of the generated gas can increase the formation pressure and expand the swept volume of the oil displacement. The generated foam can block the high-permeability channels, adjust the fluid flow direction, enabling the displacement fluid to enter the microscopic reservoir space of the oil reservoir more deeply and displace the remaining oil therein. In addition, the reactants and products of the in-situ chemical pyrolysis plugging removal technology are non-toxic, harmless, and environmentally friendly, and the reaction process is multi-stage initiated by the action of temperature, effectively avoiding the problem of serious heat loss near the wellbore. It has the functions of deep plugging removal and reducing the viscosity of heavy oil. In addition, the in-situ chemical pyrolysis plugging removal technology has a profile control effect, which can achieve the effect of increasing oil production and controlling water cut in heterogeneous reservoirs and improving the crude oil production.

[0052] In one feasible embodiment, the target chemical agent includes at least one of dimethyl fumarate and chitosan, a foaming agent, and a flaky nano foam stabilizer constructed by the double-fluid method. Among them, the double-fluid method refers to injecting two mutually independent liquids (the two liquids are respectively called "the first liquid" and "the second liquid") that can undergo a chemical reaction under formation conditions into the formation sequentially or simultaneously. After the two liquids meet in the high-permeability area of the reservoir, a substance with plugging ability (such as gel, precipitate, polymer gel, etc.) is generated, thereby selectively plugging the high-permeability layer section, adjusting the seepage direction of the injected fluid, forcing the subsequent injected water to turn to the low-permeability area, expanding the swept volume, and increasing the crude oil recovery rate.

[0053] In one feasible embodiment, the foaming agent is a surfactant capable of forming stable foam in a liquid, and the foaming agent is an anionic surfactant. The foam generated by the foaming agent can achieve the control of fluid mobility, the adjustment of reservoir seepage channels, and the efficient displacement of remaining oil.

[0054] In one feasible embodiment, the sheet-like nano foam stabilizer is a functional material with a nano-scale sheet structure. The sheet-like nano foam stabilizer can adsorb at the gas-liquid interface and form a high-strength interfacial film, significantly enhancing the stability of the foam. It can cooperate with traditional foaming agents to solve the problem of easy foam rupture under extreme conditions.

[0055] Figure 2 The flowchart of a method for displacing oil in a high-dip heavy oil reservoir according to an embodiment of the present disclosure is shown Figure 2 , such as Figure 2 shown. Step S105, "Based on the steam flooding slug technology, assist in displacing the remaining oil in the oil well after displacement", includes:

[0056] Step S201, based on the test slug technology, inject fresh water or oilfield water into the target formation in the oil well. Through the pressure change, flow rate data, and formation liquid absorption rate during the injection process, determine the liquid absorption capacity and permeability characteristics of the formation, and determine the distribution of high-permeability channels and low-permeability regions.

[0057] In this embodiment, when implementing the steam flooding slug technology, first perform the test slug operation, inject fresh water or oilfield water into the target formation of the oil well. During the injection process, real-time monitor the change of injection pressure, flow rate data, and the formation liquid absorption rate. Through the analysis of the pressure change, flow rate data, and formation liquid absorption rate, the liquid absorption capacity of the formation can be accurately determined, and the permeability characteristics of the formation can be understood, including the magnitude and distribution of the permeability. At the same time, the distribution differences between high-permeability channels and low-permeability regions can also be identified. High-permeability channels are usually the paths where steam is likely to break through during the steam flooding process, while low-permeability regions are the regions that have not been effectively utilized.

[0058] Step S202, based on the plugging slug technology, use gel particles as a channel plugging agent to plug the high-permeability channels.

[0059] In this embodiment, after determining the positions of the high-permeability channels according to the test slug, the plugging slug technology can be used to inject gel particles as a channel plugging agent into the regions where these high-permeability channels are located. The gel particles react with formation water and other substances under formation conditions to form a gel-like plugging material, plugging the high-permeability channels, enabling the subsequent injected steam and other displacement agents to turn to the medium and low-permeability regions, expanding the swept volume of oil displacement, and improving the oil recovery rate.

[0060] Step S203: Based on the imbibition slug technology, inject a surfactant imbibition agent into the oil well. The agent infiltrates into the low-permeability area under the action of capillary force, stripping the remaining oil on the rock surface to form an emulsion flow.

[0061] In this embodiment, after plugging the high-permeability channels, the imbibition slug technology can be implemented to inject a surfactant imbibition agent into the oil well. Under the action of capillary force in the formation, the surfactant imbibition agent can infiltrate into the tiny pores and pore throats in the low-permeability area. At the same time, the characteristics of its surfactant can strip the remaining oil adsorbed on the rock surface to form an emulsion flow, increasing the recoverable crude oil volume.

[0062] Step S204: Based on the self-generated gas foam slug, adopt a self-generated gas foam system to generate gas through a chemical reaction to form foam, displace the pore crude oil, and turn the displacement fluid multiple times.

[0063] In this embodiment, using the self-generated gas foam slug technology, inject a self-generated gas foam system. The self-generated gas foam system undergoes a chemical reaction in the formation to generate gas and form foam. The foam can displace the crude oil in the pores and change its flow direction multiple times during the flow process, realizing multiple-turn displacement of the fluid, improving the oil displacement efficiency, expanding the oil displacement swept area, and enabling the remaining oil originally dispersed in the pores to be effectively displaced.

[0064] Step S205: Based on the displacement fluid slug, use fresh water or oilfield water to push the chemical agent into the formation to form an isolation zone, so that the chemical agent can fully contact and react with the crude oil.

[0065] In this embodiment, the displacement fluid slug technology can also be implemented. Use fresh water or oilfield water to push various previously injected chemical agents deep into the formation to form an isolation zone, thereby preventing the chemical agent from flowing back, ensuring that the chemical agent system fully contacts and reacts with the crude oil, exerting its oil displacement and profile control effects, and improving the recovery rate of crude oil.

[0066] The present disclosure is applicable to high-dip heavy oil reservoirs and can improve the recovery rate in the middle and late stages of reservoir development. For example, for a high-dip heavy oil reservoir in a certain oilfield, after the conventional steam flooding reaches a recovery rate index of 60.67% - 53.33%, using the method of the present disclosure can further increase the recovery rate by 11.87% - 15.14%. The numerical simulation results are consistent with the physical simulation results, and the proportion of increased recovery rate after injecting the composite chemical agent is between 7.2% and 15.6%.

[0067] To facilitate the understanding of the present disclosure, the following takes Well A in a heavy oil reservoir with a formation dip angle of 30° and in the middle and late stages of development as an example to explain the oil displacement method for high-dip heavy oil reservoirs in the present disclosure:

[0068] S1, analyze the distribution characteristics of the remaining oil in Well A and identify the different types of remaining oil. For Well A, the structural dip and fault development are the main controlling factors of the macroscopic remaining oil distribution. The gravity differentiation caused by the formation dip makes it easier for steam drive to form a dominant displacement channel along the lower part of the dip direction, with a higher displacement efficiency; while the reservoir along the upper part of the dip direction has a cross displacement efficiency due to gravity. The presence of faults will make it easier for the injected steam to quickly penetrate along the dominant seepage channel formed by the faults, and the remaining oil in the reservoir around the faults is relatively richer. Combined with the geological characteristics of the Well A reservoir and the supporting steam injection process, the macroscopic remaining oil is divided into two categories: uncontrolled remaining oil and well-controlled remaining oil. Combined with the actual situation of Well A and the understanding of physical simulation, the microscopic remaining oil is divided into two categories: adsorbed remaining oil and shielded remaining oil.

[0069] S2, improve the fluid seepage path and adjust the injection profile. In Well A, due to the large proportion of macroscopic residual oil caused by physical property differences and process constraints, conventional displacement agents are prone to degradation and failure. Therefore, a new high-temperature resistant gel displacement system is used to selectively block the steam drive advantage channel, guide the subsequent functional agent segment plugs and steam thermal fluids to redirect inefficient or unused reservoir areas, so as to efficiently utilize the macroscopic residual oil formed by physical property differences and development process limitations, and promote the coordinated improvement of reservoir balanced utilization and crude oil recovery rate.

[0070] S3, stripping the crude oil on the pore surface, the crude oil is out of the adsorption state. The heavy oil in the reservoir has high viscosity and poor fluidity, and the remaining oil is easily retained in the tiny pore throats. It is necessary to use the efficient stripping characteristics of the imbibition agent to separate the residual oil adsorbed on the pore throat surface and recover it through the subsequent oil recovery process, so as to achieve the purpose of improving the crude oil recovery rate.

[0071] S4, deep reservoir unblocking, improve crude oil recovery. Since the formation is rich in microscopic residual oil, but steam cannot enter effectively, it is necessary to rely on the microscopic displacement technology of the self-generated chemical thermal unblocking technology in the formation. Through the self-generated chemical thermal unblocking technology in the formation, the heat, gas, foam and other substances generated by the reaction are used to enter the microscopic storage space that cannot be reached by the early steam drive, displace the residual oil in it, and recover it in combination with the subsequent oil recovery process.

[0072] S5, expand the scope of influence and displace the remaining oil production. Relying on the subsequent steam drive plug technology, the scope of influence is expanded by injecting high-temperature steam, using heat to reduce the viscosity of crude oil and strip the remaining oil in the pores. At the same time, the gas and foam generated by the self-generating technology are combined to further displace the remaining oil in the microscopic pores and low permeability areas. The expansion of gas increases the displacement pressure, and the foam blocks the high permeability channel, forcing the fluid to enter the low permeability area and push the remaining oil to flow to the production well.

[0073] When the formation dip angle is 30°, the gravity override effect of steam flooding is relatively obvious, and the displacement front tends to drive the upper crude oil upward. Therefore, the oil displacement efficiency of steam flooding is relatively low (53.33%). However, under the combined action of the inorganic profile control agent, imbibition agent, and self - generating heat system disclosed in this disclosure, the subsequently injected steam can enter the lower or low - permeability areas that were not able to be entered before, further increasing the crude oil displacement efficiency by 15.14%. The final recovery rate reaches 68.47%, and the oil displacement effect is good.

[0074] It should be understood that various forms of the processes shown above can be used, with steps reordered, added, or deleted. For example, the steps described in this disclosure can be executed in parallel, sequentially, or in a different order, as long as the desired results of the technical solutions disclosed in this disclosure can be achieved. No limitations are imposed herein.

[0075] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In the description of this disclosure, "a plurality" means two or more, unless otherwise specifically defined.

[0076] As described above, the above are only specific embodiments of this disclosure, but the protection scope of this disclosure is not limited thereto. Any person skilled in the art within the technical scope disclosed in this disclosure can easily think of changes or substitutions, which should all be covered within the protection scope of this disclosure. Therefore, the protection scope of this disclosure should be subject to the protection scope of the claimed rights.

Claims

1. An oil displacement method for high dip heavy oil reservoirs, characterized in that The method includes: Based on the three-dimensional geological data and production data of the oil well, determining the distribution characteristics and types of remaining oil in the oil well; the three-dimensional geological data includes the structural dip angle of the oil well, fault development characteristics, and reservoir heterogeneity data, and the production data includes the logging data, rock physical property data, pressure data, production performance curve, and production data of the oil well; Based on the distribution characteristics and types of the remaining oil, using a gel profile control agent to plug the steam drive channeling channel; Based on a wicking agent to strip the crude oil on the surface of the pores and pore throats in the plugged oil well; Based on the in-situ chemical heat treatment technology in the layer, displacing the remaining oil in the microscopic reservoir space in the oil well after stripping; Based on the steam drive slug technology, assisting in displacing the remaining oil in the oil well after displacement; the steam drive slug technology consists of multiple functional slugs; Among them, the determining the distribution characteristics and types of the remaining oil in the oil well based on the three-dimensional geological data and production data of the oil well includes: Based on the three-dimensional geological data, through the layer series division method and sedimentary facies analysis method, determining the areas where remaining oil may exist, and based on the areas where remaining oil may exist, determining the distribution characteristics of the remaining oil; Based on the production data and the distribution characteristics, through numerical simulation methods and physical simulation methods, determining the types of the remaining oil; the production data is all the data collected during the entire life cycle of the oil well, and the production data includes oil well attribute data and oil well operation data; Among them, the using a gel profile control agent to plug the steam drive channeling channel based on the distribution characteristics and types of the remaining oil includes: Based on the distribution characteristics and types of the remaining oil, determining the steam drive channeling channel; the steam drive channeling channel includes at least one of high-permeability layers, natural fractures, and channels formed by long-term water injection; Based on the gel profile control agent to plug the steam drive channeling channel; the gel profile control agent is based on inorganic polymers and forms a plugging body with a gel structure through the reaction of ammonia-based coagulants and stabilizers; Among them, the assisting in displacing the remaining oil in the oil well after displacement based on the steam drive slug technology includes: Based on the test slug technology, injecting fresh water or oilfield water into the target formation in the oil well, and through the pressure changes, flow rate data, and formation liquid absorption rate during the injection process, determining the liquid absorption capacity and permeability characteristics of the formation, and determining the distribution of high-permeability channels and low-permeability regions; Based on the plugging slug technology, using gel particles as a channel plugging agent to plug the high-permeability channels; Based on the wicking slug technology, injecting a surfactant wicking agent into the oil well, and using the capillary force to penetrate into the low-permeability regions to strip the remaining oil on the rock surface to form an emulsion flow; Based on the self-generated gas foam slug, using a self-generated gas foam system to generate gas through a chemical reaction to form foam, displace the pore crude oil, and turn the displacement fluid multiple times; Based on the displacement fluid slug, using fresh water or oilfield water to push the agent into the formation to form an isolation zone, so that the agent can fully contact and react with the crude oil.

2. The method according to claim 1, wherein The types of the remaining oil include macroscopic remaining oil and microscopic remaining oil, the macroscopic remaining oil includes unwell-controlled remaining oil and well-controlled remaining oil, and the microscopic remaining oil includes adsorbed remaining oil and shielded remaining oil.

3. The method according to claim 1, wherein The described fault development characteristics include at least one of lithological and sedimentary characteristics, porosity and permeability characteristics, structure and fracture development, thermophysical properties, and fluid and pressure characteristics; The described oil well attribute data includes at least one of logging data, rock physical property data, geophysical and geological data, completion data, and reservoir fluid property data; The described oil well operation data includes at least one of pressure data, production performance curve, reservoir dynamic response data, and production rate data.

4. The method according to claim 1, wherein The described ammonia-based coagulation accelerator is a coagulation accelerator mainly composed of an organic compound containing an amino group or an amine group.

5. The method according to claim 1, characterized in that The described imbibition agent is a small molecule aggregate formed with a nano-core as the core and a short-chain imbibition agent as the shell; the diameter of the nano-core is 7-8 nm.

6. The method according to claim 1, characterized in that, The described in-situ chemical pyrolysis plugging removal technology refers to a technology of injecting a target chemical agent into the formation of an oil well, and displacing the remaining oil in the microscopic reservoir space in the oil well after peeling by the heat, gas, and foam generated by the chemical reaction of the target chemical agent in the formation.

7. The method according to claim 6, wherein The described target chemical agent includes at least one of dimethyl fumarate and chitosan, a foaming agent, and a flaky nano foam stabilizer constructed by the double-fluid method; The described foaming agent is a surfactant capable of forming stable foam in a liquid, and the foaming agent is an anionic surfactant; The described flaky nano foam stabilizer is a functional material with a nano-scale lamellar structure.

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