Judgment method for super heavy oil vertical well section production degree

Abstract

A method for judging the production degree of a section of a super-heavy oil vertical well comprises the following steps: determining a remaining oil distribution rule and an oil layer production mode by integrating longitudinal and plane oil layer production characteristics; and through a calculation formula of the vertical well throughput longitudinal section utilization rate, the vertical well throughput section utilization rate is calculated according to the throughput turns, the permeability level difference and the oil layer perforation span, and a well with the section utilization rate lower than a set value is screened out to implement a directional plugging measure. According to the method for judging the section use degree of the super-heavy oil vertical well, the section use degree of the oil well can be quickly obtained only by using a specific formula and casing related dynamic and static parameters without passing a steam suction section test, a basis and a direction are provided for later section potential tapping and measure well selection, and the method can be widely applied to the super-heavy oil vertical well and is high in accuracy. And according to the section production degree, targeted potential tapping and yield increasing measures are formulated, technical support is provided for improving the section production measures in the later stage of heavy oil high-round throughput development, the development effect is improved, and the recovery efficiency is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of petroleum production, and in particular relates to a method for judging the producing degree of a super-heavy oil vertical well profile. Background Art

[0002] The development of super-heavy oil by steam stimulation is affected by reservoir heterogeneity, perforation span and steam overlap. With the increase of development rounds, the section is unevenly utilized and the utilization degree continues to decline, which is manifested as low or no utilization of the middle and lower oil layers, and the development effect is getting worse year by year. Therefore, it is very important to clarify the utilization degree of each well, take targeted potential tapping measures, fully utilize the low-utilization and unutilized potential layers, improve the overall utilization degree, and thus improve the development effect and recovery rate of oil wells for super-heavy oil steam stimulation to stabilize production and improve efficiency.

[0003] At present, the profile production degree of vertical wells in the development of super-heavy oil by steam stimulation can only be judged through steam absorption test, and only specific double-tube wellheads can be tested. Not only is the test cost high, but it is also impossible to conduct steam absorption test on every well. The profile production characteristics and production degree under different reservoir physical properties are unclear, and the profile potential cannot be effectively tapped, which seriously affects the development effect and recovery rate of vertical wells. Summary of the invention

[0004] The purpose of the present invention is to provide a method for determining the degree of utilization of a vertical well profile of an ultra-heavy oil well in order to solve the above-mentioned problems in the prior art and provide technical support for formulating profile utilization measures in the later stage of high-cycle throughput development of heavy oil, thereby improving the development effect and increasing the recovery rate.

[0005] In order to achieve the above object, the present invention has the following technical solutions:

[0006] A method for determining the producing degree of a super-heavy oil vertical well profile comprises the following steps:

[0007] Comprehensively analyze the vertical and horizontal oil layer production characteristics to determine the remaining oil distribution law and oil layer production mode;

[0008] Through the calculation formula of the vertical well throughput longitudinal profile utilization rate, the vertical well throughput profile utilization rate is calculated according to the throughput rounds, permeability difference, and oil layer perforation span, and the wells with profile utilization rate lower than the set value are screened out to implement directional plugging measures.

[0009] As a preferred solution, the calculation formula for the vertical well throughput longitudinal profile utilization rate is:

[0010]

[0011] Where η is the utilization rate of the vertical well throughput profile; c is the throughput round; γ is the permeability difference; and d is the perforation span of the oil layer.

[0012] As a preferred solution, the step of comprehensively analyzing the vertical and horizontal oil layer production characteristics to determine the remaining oil distribution law and oil layer production pattern includes: oil well profile production pattern experiment and vertical oil layer production characteristic analysis in the study area.

[0013] Furthermore, the oil well profile production pattern experiment is based on the reservoir conditions in the study area. The experimental crude oil is mine crude oil. A physical model of the study area is established. Through multiple groups of experiments, the rock physical properties of the reservoir in the study area are determined, the profile production patterns and laws of vertical wells are systematically characterized, and the steam impact range under different steam injection strategies is depicted.

[0014] As a preferred solution, the oil well profile production model experiment includes a core triaxial stress experiment under high temperature and high pressure conditions to determine the changing law of the core rock mechanical characteristic parameters, analyze the influence of pore pressure on the core rock mechanical characteristic parameters, and establish a thermal recovery steam injection reservoir rupture mechanism.

[0015] Furthermore, the triaxial stress experiment on the core under high temperature and high pressure conditions simulates the natural cores with different physical properties in the field. Four groups of experiments are carried out according to the physical properties, with three temperatures in each group, namely room temperature, 100°C, and 200°C. A group of pore pressure experiments is also added to determine the changing law of the core rock mechanics characteristic parameters; through the established thermal recovery steam injection reservoir rupture mechanism, relevant parameter guidance is provided for steam injection and capacity expansion.

[0016] As a preferred solution, the oil well profile production mode experiment includes using artificial cores or natural cores with various permeabilities to carry out high-temperature displacement experiments through a multi-tube parallel method to determine the steam absorption and liquid production capacity and steam breakthrough pressure parameters under different steam injection policies and different reservoir physical properties, and analyze the production degree, oil recovery efficiency and recovery degree of each layer to determine the mechanism and change law of uneven production caused by vertical heterogeneity.

[0017] As a preferred solution, the oil well profile production mode experiment includes determining the physical model ratio of the quasi-three-dimensional high-temperature and high-pressure indoor physical simulation experiment based on the actual parameters of the reservoir and utilizing the principle of similarity criterion, establishing a steam throughput physical model that conforms to the actual reservoir, characterizing the longitudinal profile production characteristics under multi-layer development conditions, and conducting multiple rounds of throughput experiments to obtain changes in the steam sweep range and profile production mode laws.

[0018] As a preferred solution, the vertical oil layer production characteristic analysis in the study area is based on the research on the vertical section production of the oil layer, combined with the production dynamic monitoring data of the study area, and uses a variety of reservoir engineering methods to carry out vertical production analysis of the study area to determine the distribution of remaining oil in the horizontal and cross-sectional planes.

[0019] As a preferred solution, the vertical oil layer utilization characteristics analysis in the study area is carried out by analyzing the changes in oil layer steam absorption during multi-cycle steam injection through steam absorption profiles; the liquid production of different layers is determined through liquid production profiles, and the changes in liquid production and the degree of utilization of different layers on different profiles are analyzed by comparing the liquid production profiles measured in production wells at different stages, so as to clarify the main factors affecting the utilization 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 have multiple layers developed vertically, interlayers developed, and poor oil layer continuity. After steam huff and puff development enters the middle and late stages, due to the large vertical physical property differences, large perforation spans, and the existence of steam overburden, the vertical well profile production degree decreases year by year. It is necessary to clarify the profile production law, formulate targeted potential tapping and production increase measures, and provide technical support for improving the profile production measures in the late stage of heavy oil high-cycle huff and puff development, thereby improving the development effect and increasing the recovery rate. The present invention studies the vertical well profile production law under different reservoir conditions, different perforation spans, and different injection and production parameters, clarifies that the vertical well profile production is affected by the reservoir permeability difference, perforation span, and huff and puff rounds, and sets different permeability differences, perforation spans, and huff and puff rounds for numerical simulation. Through orthogonal analysis, a calculation formula for the vertical well huff and puff longitudinal profile production rate is established, and relevant geological parameters are introduced to obtain the oil well profile production degree, which is convenient and fast, and the compliance rate is as high as more than 90%. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The following description and drawings, which constitute a part of this application, are used to provide a further understanding of the present invention. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0023] Figure 1 The vertical production degree contour map of the Chong 18 well area in the embodiment of the present invention. DETAILED DESCRIPTION

[0024] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0025] It should be noted that, unless otherwise specified, all technical and scientific terms used in this application have the same meanings as commonly understood by ordinary technicians in the technical field to which this application belongs.

[0026] The present invention aims to form a set of vertical well profile production degree judgment standards and methods, and provide technical support for the formulation of profile production improvement measures in the later stage of heavy oil huff-and-puff development, thereby improving the development effect and increasing the recovery rate.

[0027] The method for determining the producing degree of a vertical well profile of super-heavy oil in an embodiment of the present invention comprises the following steps:

[0028] Comprehensively analyze the vertical and horizontal oil layer production characteristics to determine the remaining oil distribution law and oil layer production mode;

[0029] Through the calculation formula of the vertical well throughput longitudinal profile utilization rate, the vertical well throughput profile utilization rate is calculated according to the throughput rounds, permeability difference, and oil layer perforation span, and the wells with profile utilization rate lower than the set value are screened out to implement directional plugging measures.

[0030] The calculation formula for the vertical well throughput longitudinal profile utilization rate is:

[0031]

[0032] Where η is the utilization rate of the vertical well throughput profile; c is the throughput round; γ is the permeability difference; and d is the perforation span of the oil layer.

[0033] In a possible implementation, the step of comprehensively analyzing the vertical and horizontal oil layer production characteristics to determine the remaining oil distribution law and oil layer production pattern includes: oil well profile production pattern experiment and vertical oil layer production characteristic analysis in the study area.

[0034] Specifically, the oil well profile utilization mode experiment, aimed at the Badaowan Formation oil reservoir in the Chong 18 well area, which has the characteristics of discontinuous vertical oil layer development, strong reservoir heterogeneity, and loose cementation. It is developed by steam stimulation, and there are single-layer or multi-layer steam injection development. Affected by steam overlap and reservoir heterogeneity, the degree of vertical oil layer profile utilization is uneven. In this regard, a physical simulation experiment of vertical well profile utilization is carried out. Based on the reservoir conditions in the study area, the experimental crude oil is mine crude oil, and physical models such as sand filling pipe and three-dimensional steam stimulation are established. Through multiple groups of experiments, the rock physical properties of the reservoir in the study area are clarified, the profile utilization mode and law of the vertical well are systematically characterized, and the steam sweep range under different steam injection strategies is depicted.

[0035] The oil well profile production model experiment includes triaxial stress experiments on cores under high temperature and high pressure conditions: simulating natural cores with different physical properties (200mD, 500mD, 1000mD, 1500mD) on site, 4 groups of experiments were carried out according to the physical properties, with 3 temperatures in each group (normal temperature, 100℃, 200℃); a group of pore pressure experiments was supplemented to clarify the change law of the core rock mechanics 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 the core rock mechanics characteristic parameters was explained, and the thermal recovery steam injection reservoir rupture mechanism was established, providing relevant parameter guidance for the next step of steam injection and capacity expansion.

[0036] The oil well profile production mode experiment also includes three-tube parallel core experiment of artificial core (or natural core):

[0037] Natural cores were used to replace loose sandstone cores. According to different reservoir properties, three tubes were designed with three cores with permeabilities of 500mD, 1000mD and 1500mD respectively to carry out high-temperature displacement experiments. The steam absorption and liquid production capacity at different permeabilities under different steam injection policies, steam breakthrough pressure and other parameters were clarified, and the utilization degree, oil recovery efficiency and recovery degree of each layer were analyzed to clarify the mechanism and change law of uneven utilization caused by vertical heterogeneity.

[0038] The oil well profile production model experiment also includes a three-dimensional vertical well steam stimulation model experiment:

[0039] According to the actual parameters of the reservoir, using the principle of similarity criterion, the physical model ratio of the quasi-three-dimensional high-temperature and high-pressure indoor physical simulation experiment was determined, and a steam huff-and-puff physical model that conforms to the actual reservoir was established to characterize the longitudinal profile production characteristics under multi-layer development conditions. Multiple rounds of huff-and-puff experiments were carried out to study the changes in the steam sweep range and the profile production pattern.

[0040] On the other hand, the vertical oil layer production characteristics analysis in the study area is based on the research on the vertical section production of the oil layer, combined with the production dynamic monitoring data of the study area, and uses a variety of reservoir engineering methods to carry out vertical production analysis in the study area to clarify the distribution of remaining oil in the horizontal and cross-sectional planes.

[0041] The steam absorption profile is used to analyze the changes in the oil layer steam absorption during the multi-cycle steam injection process;

[0042] The liquid production conditions of different layers are determined through the liquid production profile, and the changes in liquid production and the degree of utilization of different layers on different profiles are analyzed by comparing the liquid production profiles measured in the production wells at different stages. It is clarified that the main factors affecting the utilization degree of vertical well profiles are permeability difference, perforation span and throughput cycles.

[0043] Based on the vertical and horizontal oil layer production characteristics, the remaining oil distribution law and oil layer production mode are clarified. According to the orthogonal calculation results of the influence of throughput mode, throughput rounds, permeability difference and oil layer perforation span on the longitudinal profile production, a rapid judgment formula for the vertical well throughput longitudinal profile production rate is derived. The formula is fitted through 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 production degree of the vertical well profile of super-heavy oil proposed in the embodiment of the present invention, the vertical production degree contour map of the single well in the heavy 18 well area is calculated through the rapid calculation formula of the production rate of the profile of the super-heavy oil steam huff-and-puff development in Fengcheng, as shown in FIG. Figure 1As shown, directional plugging measures were implemented on 47 oil wells with utilization rates below 60% in the preferred profile. After the implementation, the unutilized layers were effectively exploited, the oil production level of each 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 technical effect of the method of the present invention has been verified through actual production. Taking the F10642 well as an example, the well was put into production in November 2008. By 2021, the cumulative oil production was 5,000 tons, the recovery rate was 22%, the daily oil production of a single well was 0.5 tons, the oil-gas ratio was 0.04, and the production effect was poor; through the calculation formula of the utilization rate of the vertical well throughput longitudinal profile, it was found that the utilization rate was only 52%, and the lower 9.4-meter oil layer was not utilized; in order to increase the utilization rate of the well, in March 2022, selective layer steam injection measures were carried out to seal the upper high-utilization layer and reserve the lower low-utilization layer. After the measures, the oil production level was increased from 0.5 tons to 1.3 tons, the oil-gas ratio was increased from 0.04 to 0.11 tons, and all the reserved oil layers were utilized. It is estimated that the recovery rate can be increased by more than 15%, and the effect of the measures is significant.

[0046] According to the method for judging the producing degree of the super heavy oil vertical well profile of the present invention, the producing degree of the oil well profile can be quickly obtained by using a specific formula and inserting relevant dynamic and static parameters without using a steam absorption profile test, so as to provide a basis and direction for later profile potential tapping and well selection. The method can be widely applied to super heavy oil vertical wells, and the accuracy rate is as high as more than 95%.

[0047] Obviously, the above described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments described in the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0048] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates 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 and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein.

[0050] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for determining the producing degree of a super-heavy oil vertical well profile, characterized in that: The following steps are involved: Comprehensively analyze the vertical and horizontal oil layer production characteristics to determine the remaining oil distribution law and oil layer production mode; Through the calculation formula of the vertical well throughput longitudinal profile utilization rate, the vertical well throughput profile utilization rate is calculated according to the throughput rounds, permeability difference, and oil layer perforation span, and the wells with profile utilization rate lower than the set value are screened out to implement directional plugging measures.

2. The method for determining the producing degree of a vertical well profile of super-heavy oil according to claim 1, characterized in that: The calculation formula of the vertical well throughput longitudinal profile utilization rate is: Where η is the utilization rate of the vertical well throughput profile; c is the throughput round; γ is the permeability difference; and d is the perforation span of the oil layer.

3. The method for determining the producing degree of a vertical super-heavy oil well profile according to claim 1, characterized in that: The step of comprehensively analyzing the vertical and horizontal oil layer production characteristics to determine the remaining oil distribution law and the oil layer production mode includes: oil well profile production mode experiment and vertical oil layer production characteristic analysis in the study area.

4. The method for determining the producing degree of a super heavy oil vertical well profile according to claim 3 is characterized in that: The oil well profile production pattern experiment is based on the reservoir conditions in the study area. The experimental crude oil is mine crude oil. A physical model of the study area is established. Through multiple groups of experiments, the rock physical properties of the reservoir in the study area are determined, the profile production pattern and laws of the vertical well are systematically characterized, and the steam impact range under different steam injection strategies is portrayed.

5. The method for determining the producing degree of a vertical super-heavy oil well profile according to claim 4 is characterized in that: The oil well profile production model experiment includes a core triaxial stress experiment 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 a thermal recovery steam injection reservoir fracture mechanism.

6. The method for determining the producing degree of a vertical super-heavy oil well profile according to claim 5, characterized in that: The core triaxial stress experiment under high temperature and high pressure conditions simulates the natural cores with different physical properties in the field. Four groups of experiments are carried out according to the physical properties, with three temperatures in each group, namely room temperature, 100°C, and 200°C. A group of pore pressure experiments is supplemented to determine the change law of the core rock mechanics characteristic parameters; by establishing the thermal recovery steam injection reservoir rupture mechanism, relevant parameter guidance is provided for steam injection and capacity expansion.

7. The method for determining the producing degree of a vertical super-heavy oil well profile according to claim 4, characterized in that: The oil well profile production mode experiment includes using artificial cores or natural cores with various permeabilities to carry out high-temperature displacement experiments through a multi-tube parallel method to determine the steam absorption and liquid production capacity and steam breakthrough pressure parameters under different steam injection policies and different reservoir physical conditions, and analyze the production degree, oil recovery efficiency and recovery degree of each layer to determine the mechanism and change law of uneven production caused by vertical heterogeneity.

8. The method for determining the producing degree of a vertical super-heavy oil well profile according to claim 4, characterized in that: The oil well profile production mode experiment includes determining the physical model proportion of the quasi-three-dimensional high-temperature and high-pressure indoor physical simulation experiment based on the actual parameters of the reservoir and utilizing the principle of similarity criterion, establishing a steam throughput physical model that conforms to the actual reservoir, characterizing the vertical profile production characteristics under multi-layer development conditions, and conducting multiple rounds of throughput experiments to obtain changes in the steam sweep range and the profile production mode laws.

9. The method for determining the producing degree of a vertical super-heavy oil well profile according to claim 3, characterized in that: The vertical oil layer production characteristics analysis in the study area is based on the research on the vertical section production of the oil layer, combined with the production dynamic monitoring data of the study area, and uses a variety of reservoir engineering methods to carry out vertical production analysis in the study area to determine the distribution of remaining oil in the horizontal and cross-sectional planes.

10. The method for determining the producing degree of a vertical super-heavy oil well profile according to claim 9, characterized in that: The analysis of the vertical oil layer utilization characteristics in the study area is carried out by analyzing the changes in oil layer steam absorption during multi-cycle steam injection through steam absorption profiles; the liquid production of different layers is determined through liquid production profiles, and the changes in liquid production and the degree of utilization of different layers on different profiles are analyzed by comparing the liquid production profiles measured in production wells at different stages, so as to clarify the main factors affecting the utilization degree of vertical well profiles.

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