A method for judging a direct-well profile producing degree of super-heavy oil

Abstract

A method for determining the utilization level of a vertical well profile in extra-heavy oil includes the following steps: comprehensively considering the vertical and planar reservoir utilization characteristics to determine the remaining oil distribution pattern and reservoir utilization mode; calculating the vertical well huff and puff profile utilization rate using a formula based on the huff and puff cycle, permeability difference, and reservoir perforation span; and selecting wells with utilization rates below a set value for targeted plugging measures. According to this invention, the method for determining the utilization level of a vertical well profile in extra-heavy oil can quickly determine the well profile utilization level without steam intake profile testing, simply by using a specific formula and applying relevant dynamic and static parameters. This provides a basis and direction for subsequent potential tapping and well selection, and is widely applicable to vertical wells in extra-heavy oil with high accuracy. Based on the utilization level, targeted potential tapping and production enhancement measures can be formulated, providing technical support for improving profile utilization measures in the later stages of high-cycle huff and puff development of heavy oil, improving development effects, and increasing recovery rates.

Description

Technical Field

[0001] This invention belongs to the field of petroleum extraction technology, specifically relating to a method for judging the degree of activation of a vertical well profile for extra-heavy oil. Background Technology

[0002] The development of extra-heavy oil using steam huff and puff is affected by reservoir heterogeneity, perforation span, and steam over-coverage. With increasing development cycles, uneven profile utilization and a continuously declining utilization rate are observed, manifesting as low or no utilization of the middle and lower oil layers, leading to a gradual deterioration in development effectiveness. Therefore, clearly defining the utilization level of each well and implementing targeted potential-tapping measures to fully utilize low-utilization and unutilized potential zones is crucial for improving overall utilization, thereby enhancing well development efficiency and recovery rates, and ensuring stable and efficient production of extra-heavy oil using steam huff and puff.

[0003] Currently, the extent of profile activation in vertical wells developed by steam huff and puff for extra-heavy oil can only be determined through steam intake testing, and this testing can only be conducted at specific dual-tube wellheads. Not only is the testing cost high, but it is also impossible to conduct steam intake testing on every well. The profile activation characteristics and extent of activation are unclear under different reservoir properties, making it impossible to effectively tap the profile potential and seriously affecting the development effect and recovery rate of vertical wells. Summary of the Invention

[0004] The purpose of this invention is to address the problems in the prior art by providing a method for judging the activation level of the profile in a vertical well for extra-heavy oil, providing technical support for formulating profile activation measures in the later stages of high-cycle huff and puff development of heavy oil, thereby improving development results and increasing recovery rate.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A method for determining the activation level of an extra-heavy oil vertical well profile includes the following steps:

[0007] By combining vertical and horizontal reservoir dynamics characteristics, the distribution pattern of remaining oil and reservoir dynamics patterns can be determined.

[0008] The utilization rate of the vertical well's spitting profile is calculated using the formula for the spitting cycle, permeability difference, and perforation span of the oil layer. Wells with a utilization rate lower than the set value are then selected for targeted plugging measures.

[0009] As a preferred embodiment, the formula for calculating the utilization rate of the vertical well's feed-through longitudinal profile is as follows:

[0010]

[0011] In the formula, η is the vertical well huff and puff profile utilization rate; c is the huff and puff cycle; γ is the permeability difference; and d is the oil layer perforation span.

[0012] As a preferred embodiment, the steps for determining the remaining oil distribution pattern and oil layer activation mode by integrating the vertical and horizontal oil layer activation characteristics include: well profile activation mode experiments and vertical oil layer activation characteristic analysis of the study area.

[0013] Furthermore, the well profile activation mode experiment is based on the reservoir conditions of the study area, and the experimental crude oil is field crude oil. A physical model of the study area is established. Through multiple sets of experiments, the physical properties of the reservoir rocks in the study area are determined, the profile activation mode and law of vertical wells are systematically characterized, and the steam sweep range under different steam injection strategies is depicted.

[0014] As a preferred option, the well profile activation mode experiment includes a triaxial stress experiment of the core under high temperature and high pressure conditions to determine the variation law of the core rock mechanical characteristic parameters, analyze the influence of pore pressure on the core rock mechanical characteristic parameters, and establish the fracture mechanism of the thermal recovery steam injection reservoir.

[0015] Furthermore, the triaxial stress test of the core under high temperature and high pressure conditions simulates natural cores with different physical properties in the field. Four sets of experiments were carried out according to physical properties, with three temperatures in each set: room temperature, 100℃, and 200℃. An additional set of pore pressure test was also conducted to determine the variation law of the rock mechanical characteristic parameters of the core. Through the established thermal recovery steam injection reservoir fracturing mechanism, relevant parameters were provided to guide steam injection and capacity expansion.

[0016] As a preferred option, the well profile activation mode experiment includes using artificial or natural cores with various permeabilities to conduct high-temperature displacement experiments through a multi-pipe parallel connection. This determines the steam absorption, liquid production capacity, and steam breakthrough pressure parameters under different steam injection policies and reservoir properties. It also analyzes the activation degree, oil displacement efficiency, and recovery degree of each layer, and determines the mechanism and variation law of activation unevenness caused by vertical heterogeneity.

[0017] As a preferred embodiment, the well profile activation mode experiment includes determining the physical model ratio of the pseudo-three-dimensional high-temperature and high-pressure indoor physical simulation experiment based on the actual parameters of the reservoir and using the principle of similarity criteria, establishing a steam injection physical model that conforms to the actual reservoir, characterizing the vertical profile activation characteristics under multi-layer system development conditions, conducting multiple rounds of injection experiments, and obtaining the changes in steam sweep range and the law of profile activation mode.

[0018] As a preferred approach, the longitudinal oil reservoir activation characteristic analysis of the study area is based on the longitudinal profile activation study of the oil reservoir, combined with the production dynamic monitoring data of the study area, and utilizes various reservoir engineering methods to conduct longitudinal activation analysis of the study area and determine the distribution of remaining oil on the plan and profile.

[0019] As a preferred approach, the vertical reservoir mobilization characteristic analysis in the study area analyzes the changes in reservoir steam absorption during multi-cycle steam injection using steam absorption profiles; it determines the fluid production situation of different layers using production profiles; and by comparing the production profiles measured in production wells at different stages, it analyzes the changes in fluid production and mobilization degree of different layers on different profiles, and clarifies the main factors affecting the mobilization degree of vertical well profiles.

[0020] Compared with the prior art, the present invention has at least the following beneficial effects:

[0021] Heavy oil reservoirs are characterized by multiple vertically developed layers with interlayers and poor oil layer continuity. In the mid-to-late stages of steam injection development, the utilization rate of vertical well profiles gradually decreases due to significant differences in vertical physical properties, large perforation spans, and steam over-coverage. It is necessary to clarify the profile utilization patterns and formulate targeted potential-tapping and production-enhancing measures to provide technical support for improving profile utilization in the later stages of high-cycle steam injection development of heavy oil, thereby improving development efficiency and increasing recovery rates. This invention studies the vertical well profile utilization patterns under different reservoir conditions, perforation spans, and injection-production parameters. It clarifies that vertical well profile utilization is affected by reservoir permeability differences, perforation spans, and steam injection cycles. Numerical simulations were conducted with different permeability differences, perforation spans, and steam injection cycles. An orthogonal analysis was used to establish a calculation formula for the vertical well steam injection longitudinal profile utilization rate. By importing relevant geological parameters, the well profile utilization rate can be obtained conveniently, quickly, and with a consistency rate of over 90%. Attached Figure Description

[0022] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0023] Figure 1 Contour map of the vertical mobilization level in the Chong 18 well area in this embodiment of the invention. Detailed Implementation

[0024] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0025] It should be noted that, unless otherwise specified, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0026] The present invention aims to establish a set of standards and methods for judging the degree of vertical well profile activation, providing technical support for formulating measures to improve profile activation in the later stages of heavy oil huff and puff development, thereby improving development results and increasing recovery rate.

[0027] The method for determining the degree of activation of the profile of an extra-heavy oil vertical well according to an embodiment of the present invention includes the following steps:

[0028] By combining vertical and horizontal reservoir dynamics characteristics, the distribution pattern of remaining oil and reservoir dynamics patterns can be determined.

[0029] The utilization rate of the vertical well's spitting profile is calculated using the formula for the spitting cycle, permeability difference, and perforation span of the oil layer. Wells with a utilization rate lower than the set value are then selected for targeted plugging measures.

[0030] The formula for calculating the utilization rate of the vertical well's feed-through longitudinal profile is as follows:

[0031]

[0032] In the formula, η is the vertical well huff and puff profile utilization rate; c is the huff and puff cycle; γ is the permeability difference; and d is the oil layer perforation span.

[0033] In one possible implementation, the step of determining the remaining oil distribution pattern and oil layer activation pattern by integrating the longitudinal and planar oil layer activation characteristics includes: well profile activation pattern experiments and analysis of the longitudinal oil layer activation characteristics in the study area.

[0034] Specifically, the well profile activation model experiment was conducted. This study addressed the characteristics of the Badaowan Formation reservoir in the Chong 18 well area, which features discontinuous vertical oil layer development, strong reservoir heterogeneity, and loose cementation. Development was carried out using steam injection, involving single-layer or multi-layer steam injection. Due to steam over-coverage and reservoir heterogeneity, the degree of vertical oil layer profile activation was uneven. To address this, a physical simulation experiment of vertical well profile activation was conducted. Based on the reservoir conditions of the study area and using field crude oil, physical models such as sand-filled pipes and three-dimensional steam injection were established. Through multiple sets of experiments, the physical characteristics of the reservoir rocks in the study area were clarified, the profile activation mode and laws of vertical wells were systematically characterized, and the steam sweep range under different steam injection strategies was depicted.

[0035] The well profile activation model experiment included triaxial stress experiments on cores under high temperature and high pressure conditions: simulating natural cores with different physical properties (200mD, 500mD, 1000mD, 1500mD), four sets of experiments were conducted according to physical properties, with three temperatures per set (normal temperature, 100℃, 200℃); a supplementary set of pore pressure experiments was added, clarifying the variation law of core rock mechanical characteristic parameters: first, the higher the permeability and temperature, the lower the compressive strength; second, the higher the permeability and temperature, the lower the elastic modulus; third, the higher the permeability and temperature, the higher the Poisson's ratio. The influence of pore pressure on core rock mechanical characteristic parameters was elucidated, and a fracture mechanism for thermal recovery steam injection reservoirs was established, providing relevant parameter guidance for subsequent steam injection and capacity expansion.

[0036] The well profile mobilization model experiment also includes a three-tube parallel core experiment using artificial (or natural) cores:

[0037] Using natural cores instead of loose sandstone cores, and based on different reservoir properties, three-tube systems were designed to use cores with three permeabilities of 500mD, 1000mD, and 1500mD respectively for high-temperature displacement experiments. The steam absorption and production capacity, steam breakthrough pressure, and other parameters under different steam injection policies and permeabilities were clarified. The utilization degree, oil displacement efficiency, and recovery degree of each layer were analyzed, and the mechanism and variation law of the uneven utilization caused by vertical heterogeneity were clarified.

[0038] The well profile activation model experiment also includes a three-dimensional vertical well steam injection model experiment:

[0039] Based on the actual parameters of the reservoir, the physical model ratio of the pseudo-three-dimensional high-temperature and high-pressure indoor physical simulation experiment was determined using the principle of similarity criteria. A steam injection physical model that conforms to the actual reservoir was established to characterize the longitudinal profile dynamics under multi-layer system development conditions. Multiple rounds of injection experiments were carried out to study the changes in steam sweep range and the dynamics of the profile.

[0040] On the other hand, the longitudinal oil reservoir activation characteristic analysis of the study area, based on the longitudinal profile activation study of the oil reservoir, combined with the production dynamic monitoring data of the study area, uses a variety of reservoir engineering methods to carry out the longitudinal activation analysis of the study area, and clarifies the distribution of the remaining oil on the plan and profile.

[0041] The changes in oil reservoir steam absorption during multi-cycle steam injection were analyzed by steam absorption profile analysis.

[0042] By determining the production conditions of different layers through production profiles, and by comparing the production profiles measured in production wells at different stages, the changes and utilization of production in different layers on different profiles are analyzed. It is clear that the main factors affecting the utilization of vertical well profiles are permeability gradient, perforation span, and throughput cycles.

[0043] By combining the characteristics of vertical and planar reservoir utilization, the distribution pattern of remaining oil and reservoir utilization mode are clarified. Based on the orthogonal calculation results of the influence of huff and puff mode, huff and puff cycle, permeability difference, and reservoir perforation span on vertical profile utilization, a rapid judgment formula for vertical well huff and puff longitudinal profile utilization rate is derived. The formula is fitted by steam absorption test, and the compliance rate is over 90%, which verifies the reliability and rationality of the evaluation method.

[0044] According to the method for judging the utilization level of vertical well profiles for extra-heavy oil proposed in this invention, the Fengcheng extra-heavy oil steam huff and puff development uses a rapid calculation formula for profile utilization rate to calculate the contour map of the vertical utilization level of a single well in the Chong 18 well area, as shown in the figure. Figure 1As shown, directional plugging measures were implemented on 47 oil wells with a profile utilization rate of less than 60%. After implementation, the unutilized layers were effectively exploited, the oil production level of a single well increased by 0.6 tons, the oil-gas ratio increased by 0.04, the input-output ratio was 1:1.5, and the recovery rate was effectively increased by more than 10%.

[0045] The method of this invention has been verified through actual production. Taking well F10642 as an example, this well was put into production in November 2008. By 2021, it had produced a cumulative oil production of 5,000 tons, with a recovery rate of 22%. The daily oil production per well was 0.5 tons, and the oil-gas ratio was 0.04, indicating poor production performance. Through the calculation formula of the vertical profile utilization rate of vertical wells, it was found that the utilization rate was only 52%, and the lower 9.4 meters of oil layer was not utilized. In order to improve the utilization rate of this well, selective steam injection measures were carried out in March 2022 to seal the upper high-utilization layer and reserve the lower low-utilization layer. After the measures, the oil production level increased from 0.5 tons to 1.3 tons, the oil-gas ratio increased from 0.04 to 0.11 tons, and all the reserved oil layer was utilized. It is estimated that the recovery rate can be increased by more than 15%, and the measures have significant effects.

[0046] According to the method for judging the activation level of the profile of ultra-heavy oil vertical wells of the present invention, the activation level of the oil well profile can be quickly determined by simply using a specific formula and applying relevant dynamic and static parameters without the need for steam intake profile testing. This provides a basis and direction for subsequent potential tapping of the profile and well selection of measures. It can be widely applied to ultra-heavy oil vertical wells and has an accuracy rate of over 95%.

[0047] Obviously, the embodiments described above are merely some, not all, embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments described herein without inventive effort should fall within the scope of protection of the present invention.

[0048] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0049] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in sequences other than those illustrated or described herein.

[0050] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for determining the degree of activation of a vertical well profile in extra-heavy oil, characterized in that, Includes the following steps: By combining vertical and horizontal reservoir dynamics characteristics, the distribution pattern of remaining oil and reservoir dynamics patterns can be determined. The utilization rate of the vertical well's vertical profile is calculated using the formula for calculating the vertical well's huff and puff cycle, permeability difference, and oil layer perforation span. Wells with a utilization rate lower than the set value are then selected for targeted plugging measures. The steps for determining the remaining oil distribution pattern and oil layer activation pattern by comprehensively considering the vertical and horizontal oil layer activation characteristics include: oil well profile activation pattern experiments and vertical oil layer activation characteristic analysis in the study area; The well profile activation mode experiment is based on the reservoir conditions of the study area, the experimental crude oil is field crude oil, a physical model of the study area is established, and through multiple sets of experiments, the physical properties of the reservoir rocks in the study area are determined, the profile activation mode and law of vertical wells are systematically characterized, and the steam sweep range under different steam injection strategies is depicted. The longitudinal reservoir utilization characteristic analysis of the study area is based on the longitudinal profile utilization study of the reservoirs. Combined with the production dynamic monitoring data of the study area, various reservoir engineering methods are used to carry out the longitudinal utilization analysis of the study area to determine the distribution of remaining oil on the horizontal and vertical sections. The steam absorption profile is used to analyze the changes in steam absorption of the reservoirs during multiple steam injection cycles. The production profile is used to determine the production situation of different layers. By comparing the production profiles measured in production wells at different stages, the changes in production of different layers on different profiles and the degree of utilization are analyzed to identify the main factors affecting the degree of utilization of vertical well profiles. The formula for calculating the utilization rate of the vertical well's feed-through longitudinal profile is as follows: In the formula, η For vertical well throughput profile utilization rate; c γ represents the throughput cycle; γ represents the permeability gradient. d This represents the span of the oil layer perforation.

2. The method for determining the degree of activation of the profile of an extra-heavy oil vertical well according to claim 1, characterized in that, The well profile activation mode experiment includes triaxial stress experiments on cores under high temperature and high pressure conditions to determine the variation law of core rock mechanical characteristic parameters, analyze the influence of pore pressure on core rock mechanical characteristic parameters, and establish the fracture mechanism of thermal recovery steam injection reservoir.

3. The method for determining the degree of activation of the profile of an extra-heavy oil vertical well according to claim 2, characterized in that, The triaxial stress test of the core under high temperature and high pressure simulates natural cores with different physical properties in the field. Four sets of experiments were carried out according to physical properties, with three temperatures in each set: room temperature, 100℃, and 200℃. An additional set of pore pressure test was also conducted to determine the variation law of the rock mechanical characteristic parameters of the core. By establishing the fracture mechanism of the thermal recovery steam injection reservoir, relevant parameters are provided to guide steam injection and capacity expansion.

4. The method for determining the degree of activation of the profile of an extra-heavy oil vertical well according to claim 1, characterized in that, The well profile utilization model experiment includes using artificial or natural cores with various permeabilities to conduct high-temperature displacement experiments through a multi-pipe parallel connection. The experiment aims to determine the steam absorption, liquid production capacity, and steam breakthrough pressure parameters under different steam injection policies and reservoir properties. It also analyzes the utilization degree, oil displacement efficiency, and recovery degree of each layer, and determines the mechanism and variation law of the uneven utilization caused by vertical heterogeneity.

5. The method for determining the degree of activation of the profile of an extra-heavy oil vertical well according to claim 1, characterized in that, The well profile activation mode experiment includes determining the physical model ratio of the pseudo-three-dimensional high-temperature and high-pressure indoor physical simulation experiment based on the actual parameters of the reservoir and using the principle of similarity criteria, establishing a steam injection physical model that conforms to the actual reservoir, characterizing the vertical profile activation characteristics under multi-layer system development conditions, carrying out multiple rounds of injection experiments, and obtaining the changes in steam sweep range and the law of profile activation mode.

Images