阅读说明：本技术 一种定量预测及评价深层碳酸盐岩局部盖层的地球物理方法与系统 (Geophysical method and system for quantitatively predicting and evaluating local cover layer of deep carbonate rock ) 是由 李海英 高利君 杨子川 黄苇 王胜利 徐浩 刘瑞 刘成芳 于 2020-05-12 设计创作，主要内容包括：本发明公开了一种定量预测及评价深层碳酸盐岩局部盖层的地球物理方法及系统,属于复杂探区石油和天然气地震勘探技术领域,系统执行定量预测及评价深层碳酸盐岩局部盖层的方法时,使用两个定量指标即各向异性强度(＞下限门槛值)、泊松比(>0.3或下限门槛值)开展碳酸盐岩局部盖层预测评价,只要符合上述两个指标,就可以确定为碳酸盐岩局部盖层。本发明解决了目前碳酸盐岩局部盖层预测评价缺少可靠方法,包括缺少定量化指标及在实践中难以操作的难题。使用本发明方法可以开展碳酸盐岩局部盖层地球物理预测定量评价,提高碳酸盐岩局部盖层预测评价精度,从而提高勘探开发成功率。(The invention discloses a geophysical method and a geophysical system for quantitatively predicting and evaluating a local cover layer of deep carbonatite, which belong to the technical field of seismic exploration of petroleum and natural gas in a complex exploration area, wherein when the system executes the method for quantitatively predicting and evaluating the local cover layer of the deep carbonatite, the method uses two quantitative indexes, namely anisotropic strength (greater than a lower limit threshold value) and Poisson ratio (greater than 0.3 or the lower limit threshold value) to carry out prediction and evaluation on the local cover layer of the carbonatite, and can be determined as the local cover layer of the carbonatite as long as the two indexes are met. The invention solves the problems that the prediction and evaluation of the local covering layer of the carbonate rock at present lacks a reliable method, including lacking quantitative indexes and being difficult to operate in practice. By using the method, the geophysical prediction quantitative evaluation of the local cover layer of the carbonate rock can be carried out, and the prediction evaluation precision of the local cover layer of the carbonate rock is improved, so that the success rate of exploration and development is improved.)

1. A geophysical method for quantitatively predicting and evaluating a local cover layer of a deep carbonate rock is characterized by comprising the following steps of:

s1, collecting data bodies of anisotropic inversion results and Poisson ratio prestack inversion results of target intervals in a research area, and predicting and evaluating a cover layer by using two indexes of anisotropic strength and Poisson ratio;

s2, carrying out rock physical analysis on a compact layer and a reservoir stratum of a target interval in a research area, determining the anisotropic strength and the lower limit threshold value standard of the Poisson ratio of the compact layer, and determining the lower limit index of the anisotropic strength and the Poisson ratio;

s3, comparing the anisotropic strength and the Poisson ratio of the target stratum of the research area with the anisotropic strength and the lower limit index of the Poisson ratio, and taking the stratum with the anisotropic strength larger than the lower limit index of the anisotropic strength and the Poisson ratio larger than the lower limit index of the Poisson ratio as the local cover layer of the carbonate rock of the research area.

2. The geophysical method for quantitatively predicting and evaluating the local cover of the deep carbonate rock according to claim 1, wherein the anisotropic inversion result is a shear wave velocity anisotropic inversion result.

3. The geophysical method for quantitatively predicting and evaluating the local cover layer of the deep carbonate rock as claimed in claim 1, wherein normal distribution diagrams are carried out through anisotropic numerical values of the compact layer and the reservoir, and intersection point corresponding numerical values are taken as the lower limit threshold value standard of anisotropic strength of the compact layer; and using the lower limit threshold value of the anisotropic strength as a lower limit index of the anisotropic strength.

4. The geophysical method for quantitatively predicting and evaluating the deep carbonate rock local cover layer according to claim 1, wherein a normal distribution diagram is taken through the Poisson ratio values of the compact layer and the reservoir layer, and the corresponding value of an intersection point is taken as the Poisson ratio lower limit threshold value standard of the compact layer.

5. The geophysical method for quantitatively predicting and evaluating the local cover layer of the deep carbonatite as claimed in claim 4, wherein if the lower threshold Poisson ratio of the dense layer is greater than 0.3, the lower threshold is used as the lower limit index of the Poisson ratio; and if the lower limit threshold value of the Poisson ratio of the compact layer is less than 0.3, using 0.3 as the lower limit index of the Poisson ratio.

6. The geophysical method of claim 1 wherein the data that satisfy the criteria above a lower threshold is isolated and the formation to which the data corresponds is used as the local cap rock for the area under study.

7. The geophysical method for quantitatively predicting and evaluating the local cover rock of the deep carbonate rock as claimed in claim 1, wherein the plan view and the cross-sectional view which meet the index greater than the lower limit are superposed, and the stratum corresponding to the superposed plan view and the superposed cross-sectional view is used as the local cover rock of the carbonate rock in the research area.

8. A system for performing the method of any of claims 1-7, comprising:

the data body collection module is used for collecting data bodies of the anisotropic inversion result and the pre-poisson ratio inversion result of the target layer section of the research area, and predicting and evaluating the cover layer by using two indexes of anisotropic strength and poisson ratio;

the rock physical analysis module is used for performing rock physical analysis on a compact layer of a target interval and a reservoir in a research area, determining the anisotropic strength and the lower limit threshold value standard of the Poisson ratio of the compact layer, and determining the lower limit index of the anisotropic strength and the Poisson ratio;

and the prediction evaluation module is used for comparing the anisotropic strength and the Poisson ratio of the target stratum in the research area with the anisotropic strength and the Poisson ratio lower limit index, and taking the stratum with the anisotropic strength larger than the anisotropic strength lower limit index and the Poisson ratio larger than the Poisson ratio lower limit index as the local cover layer of the carbonate rock in the research area.

Technical Field

The invention relates to the technical field of seismic exploration of petroleum and natural gas in complex exploration areas, in particular to a geophysical method and a geophysical system for quantitatively predicting and evaluating a local cover layer of deep carbonate rock.

Background

The carbonate fracture-cave type oil-gas reservoir is one of the main oil-gas reservoir types in the western part of China, and the reservoir is a carbonate fracture-cave system with strong heterogeneity in space under the actions of multi-period structural fracture, ancient weathering, corrosion and the like, thereby providing an important place for oil-gas transportation and gathering. With the continuous deep expansion of carbonate rock exploration, the exploration target layer system also advances to the deep layer, and for the favorable exploration target of the deep carbonate rock, the overlying carbonate rock stratum serving as a direct cover layer can also be the reservoir layer system of the shallow exploration target, so that a plurality of sets of storage cover combinations exist. Exploration practices show that the seismic reflection characteristics of the deep fracture-cavity reservoir are influenced by the external shape, the internal structure, the fracture density, the later-stage erosion modification and other effects of the reservoir, and the seismic response characteristics of the reservoir are expressed by strong amplitude reflections such as ' beads ', ' and ' flakes ' developing along a fracture zone. The lithology of the carbonate oil and gas reservoir cover layer comprises evaporite (such as gypsum rock), shale, carbonate rock and the like, namely the carbonate rock can also be used as a local cover layer of the carbonate oil and gas reservoir, but the carbonate rock needs to meet certain conditions, such as lithology compactness, higher argillaceous content and no crack development.

The conventional carbonate local cover layer prediction and evaluation lacks a reliable prediction and evaluation method and quantitative prediction and evaluation indexes, for example, cracks are important indexes, but the conventional crack prediction method (based on seismic attributes such as coherence, curvature and ant body, and seismic attributes such as stacking amplitude, attenuation and P-wave inversion) is low in precision, is only based on qualitative analysis of three-dimensional seismic acquisition data, and is usually in search of a non-development area of a reservoir from the perspective of reservoir prediction. The concrete expression is as follows:

(1) a method for predicting a cover layer (namely a difference reservoir) based on post-stack seismic data mainly aims at finding a concept of 'strong continuity, no abnormity and fracture avoidance' on seismic reflection. Starting from three-dimensional seismic data, calibrating a local compact limestone cover layer existing in a carbonate rock inner curtain by combining actual drilling, showing strong continuous reflection on reflection characteristics, showing no special geological abnormal body, having no obvious impedance change, and showing discontinuous abnormalities such as non-development fracture cracks, tension grooves and the like in a region through conventional discontinuous detection results;

(2) based on a pre-stack prediction method, small-scale fracture and crack prediction is carried out, and the effectiveness and storage conditions of the inner cover layer in the region are evaluated by combining a pre-stack inversion result;

(3) corresponding logging analysis, rock physical analysis and rock breakthrough pressure test are carried out through data such as well drilling, well logging, coring and the like, so that the cap layer effectiveness distinguishing characteristics are established preliminarily.

Most of the early prediction and evaluation work only stays in regional internal fixed analysis or characteristic analysis, and the evaluation result has multiple solutions and cannot be popularized and applied to other regions or other strata systems.

The two indexes of Poisson's ratio and anisotropic strength are not used in the conventional carbonate rock prediction and evaluation, the Poisson's ratio is an important index parameter for evaluating whether rock is subjected to brittle failure, and simultaneously the Poisson's ratio can also be used for evaluating the content of argillaceous substances in the rock, for example, the Poisson's ratio is increased due to the high argillaceous substance content, and a large amount of rock physical analysis shows that the compact carbonate rock has the characteristic of high Poisson's ratio, and the small anisotropic strength means that cracks are not developed.

In the existing patent document, CN106948811A discloses a quantitative characterization method for capping performance of dense carbonate rock cover in a laminated basin, which considers parameters such as pressure and porosity, and tests on core breakthrough pressure and porosity can not be performed under geological conditions such as underground temperature and pressure, and depends on parameters of shale content, and basically does not consider anisotropy and crack influence. CN110231407A discloses a method for judging effectiveness of carbonate rock cover, which relies on laboratory analysis data, has a large difference with actual underground geological conditions, only considers wave impedance parameters, does not provide a quantitative evaluation method, has strong heterogeneous characteristics of underground rocks, and cannot be widely popularized by rock physical analysis close to partial rock samples.

In conclusion, the prediction and evaluation method of the deep carbonate rock in the prior art is usually qualitative research and is not quantitative; in addition, two important indexes of Poisson's ratio and anisotropy are neglected in the prior art, and the prediction effect is not ideal.

Disclosure of Invention

The invention aims to provide a geophysical method and a geophysical system for quantitatively predicting and evaluating a local cover layer of deep carbonate rock, and aims to solve the technical problems that the prediction effect is not ideal due to the fact that the prediction and evaluation of the local cover layer of the deep carbonate rock can only be qualitatively analyzed and key indexes are ignored in the prior art.

The technical scheme of the invention is as follows: a geophysical method for quantitatively predicting and evaluating a local cover layer of a deep carbonate rock is characterized by comprising the following steps of:

s1, collecting data bodies of anisotropic inversion results and Poisson ratio prestack inversion results of target intervals in a research area, and predicting and evaluating a cover layer by using two indexes of anisotropic strength and Poisson ratio;

s2, carrying out rock physical analysis on a compact layer and a reservoir stratum of a target interval in a research area, determining the anisotropic strength and the lower limit threshold value standard of the Poisson ratio of the compact layer, and determining the lower limit index of the anisotropic strength and the Poisson ratio;

s3, comparing the anisotropic strength and the Poisson ratio of the target stratum of the research area with the anisotropic strength and the lower limit index of the Poisson ratio, and taking the stratum with the anisotropic strength larger than the lower limit index of the anisotropic strength and the Poisson ratio larger than the lower limit index of the Poisson ratio as the local cover layer of the carbonate rock of the research area.

Preferably, the anisotropic inversion result is a shear wave velocity anisotropic inversion result.

Preferably, a normal distribution diagram is taken through the anisotropy values of the compact layer and the reservoir to obtain a corresponding value of an intersection point as the lower limit threshold value standard of the anisotropy strength of the compact layer; and using the lower limit threshold value of the anisotropic strength as a lower limit index of the anisotropic strength.

Preferably, a normal distribution diagram is taken through the Poisson ratio values of the compact layer and the reservoir to obtain a corresponding value of an intersection point as a Poisson ratio lower limit threshold value standard of the compact layer.

Preferably, if the lower limit threshold value of the poisson ratio of the compact layer is larger than 0.3, the lower limit threshold value is used as the lower limit index of the poisson ratio; and if the lower limit threshold value of the Poisson ratio of the compact layer is less than 0.3, using 0.3 as the lower limit index of the Poisson ratio.

Preferably, data meeting a criterion greater than a lower limit is isolated, and the formation to which the data corresponds is used as a local cover for carbonate rock in the research area.

Preferably, the plan view and the section view which meet the index larger than the lower limit are superposed, and the stratum corresponding to the superposed plan view and the superposed section view is used as the local cover layer of the carbonate rock in the research area.

The invention also provides a system for executing the method, which is characterized by comprising the following steps:

the data body collection module is used for collecting data bodies of the anisotropic inversion result and the pre-poisson ratio inversion result of the target layer section of the research area, and predicting and evaluating the cover layer by using two indexes of anisotropic strength and poisson ratio;

the rock physical analysis module is used for performing rock physical analysis on a compact layer of a target interval and a reservoir in a research area, determining the anisotropic strength and the lower limit threshold value standard of the Poisson ratio of the compact layer, and determining the lower limit index of the anisotropic strength and the Poisson ratio;

and the prediction evaluation module is used for comparing the anisotropic strength and the Poisson ratio of the target stratum in the research area with the anisotropic strength and the Poisson ratio lower limit index, and taking the stratum with the anisotropic strength larger than the anisotropic strength lower limit index and the Poisson ratio larger than the Poisson ratio lower limit index as the local cover layer of the carbonate rock in the research area.

Compared with the prior art, the invention has the beneficial effects that:

different from the traditional qualitative cover layer prediction method, the method combines the Poisson ratio of prestack inversion and the inversion result of the azimuth anisotropy, and realizes the quantitative analysis of the local dense cover layer evaluation. The concrete effects are as follows:

firstly, a reliable quantitative discrimination method which accords with geological rules is provided for prediction and evaluation of the local dense covering layer of the carbonate rock, analysis and research of seismic response characteristics of various covering layers of the deep carbonate rock and establishment of an earthquake recognition mode are facilitated, the storage layer prediction work is guided, and the recognition precision and quality are improved;

and secondly, providing scientific basis and technical support for subsequent favorable zone division, trap recognition and evaluation, target optimization, reserve calculation and the like.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.

FIG. 1 is a diagram of the operational steps of the geophysical method for quantitatively predicting and evaluating a deep carbonate local overburden of the present invention;

FIG. 2 is a schematic diagram of a geophysical system for quantitatively predicting and evaluating a deep carbonate local overburden in accordance with the present invention.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings, and it should be understood that the described embodiments are some, but not all embodiments of the present invention.

The components of embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention.

All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

Example one

A geophysical method for quantitatively predicting and evaluating a local cover layer of a deep carbonate rock is shown in figure 1 and comprises the following steps:

and S1, collecting data bodies of the anisotropic inversion result and the pre-poisson ratio inversion result of the target layer section of the research area, and predicting and evaluating the cover layer by using the anisotropic strength and the poisson ratio.

Wherein, the anisotropic inversion result is the transverse wave velocity anisotropic inversion result.

S2, carrying out rock physical analysis on a compact layer and a reservoir stratum of a target interval in a research area, determining the anisotropic strength and the lower limit threshold value standard of the Poisson ratio of the compact layer, and determining the lower limit index of the anisotropic strength and the Poisson ratio;

taking a corresponding numerical value of an intersection point as a lower limit threshold value standard of each anisotropy strength of the compact layer by taking a normal distribution diagram of each anisotropy numerical value of the compact layer and the reservoir; and using the lower limit threshold value of the anisotropic strength as a lower limit index of the anisotropic strength.

And taking a corresponding numerical value of an intersection point as a compact layer Poisson ratio lower limit threshold value standard by taking the compact layer and reservoir Poisson ratio numerical values as a normal distribution diagram.

S3, comparing the anisotropic strength and the Poisson ratio of the target stratum of the research area with the anisotropic strength and the lower limit index of the Poisson ratio, and taking the stratum with the anisotropic strength larger than the lower limit index of the anisotropic strength and the Poisson ratio larger than the lower limit index of the Poisson ratio as the local cover layer of the carbonate rock of the research area.

And isolating data meeting the index greater than the lower limit, wherein the stratum corresponding to the data is used as the local cover layer of the carbonate rock in the research area.

Example two

A geophysical method for quantitatively predicting and evaluating a local cover layer of a deep carbonate rock is shown in figure 1 and comprises the following steps:

and S1, collecting data bodies of the anisotropic inversion result and the pre-poisson ratio inversion result of the target layer section of the research area, and predicting and evaluating the cover layer by using the anisotropic strength and the poisson ratio.

Wherein, the anisotropic inversion result is the transverse wave velocity anisotropic inversion result.

S2, carrying out rock physical analysis on a compact layer and a reservoir stratum of a target interval in a research area, determining the anisotropic strength and the lower limit threshold value standard of the Poisson ratio of the compact layer, and determining the lower limit index of the anisotropic strength and the Poisson ratio;

taking a corresponding numerical value of an intersection point as a lower limit threshold value standard of each anisotropy strength of the compact layer by taking a normal distribution diagram of each anisotropy numerical value of the compact layer and the reservoir; and using the lower limit threshold value of the anisotropic strength as a lower limit index of the anisotropic strength.

And taking a corresponding numerical value of an intersection point as a compact layer Poisson ratio lower limit threshold value standard by taking the compact layer and reservoir Poisson ratio numerical values as a normal distribution diagram. Further, if the lower limit threshold value of the Poisson ratio of the compact layer is larger than 0.3, the lower limit threshold value is used as the lower limit index of the Poisson ratio; and if the lower limit threshold value of the Poisson ratio of the compact layer is less than 0.3, using 0.3 as the lower limit index of the Poisson ratio.

S3, comparing the anisotropic strength and the Poisson ratio of the target stratum of the research area with the anisotropic strength and the lower limit index of the Poisson ratio, and taking the stratum with the anisotropic strength larger than the lower limit index of the anisotropic strength and the Poisson ratio larger than the lower limit index of the Poisson ratio as the local cover layer of the carbonate rock of the research area.

And superposing the plan view and the section view which meet the index larger than the lower limit, wherein the stratum corresponding to the superposed plan view and the superposed section view is used as the local cover layer of the carbonate rock in the research area.

The present invention also provides a system for executing the method, as shown in fig. 2, including:

the data body collection module is used for collecting data bodies of the anisotropic inversion result and the pre-poisson ratio inversion result of the target layer section of the research area, and predicting and evaluating the cover layer by using two indexes of anisotropic strength and poisson ratio;

the rock physical analysis module is used for performing rock physical analysis on a compact layer of a target interval and a reservoir in a research area, determining the anisotropic strength and the lower limit threshold value standard of the Poisson ratio of the compact layer, and determining the lower limit index of the anisotropic strength and the Poisson ratio;

and the prediction evaluation module is used for comparing the anisotropic strength and the Poisson ratio of the target stratum in the research area with the anisotropic strength and the Poisson ratio lower limit index, and taking the stratum with the anisotropic strength larger than the anisotropic strength lower limit index and the Poisson ratio larger than the Poisson ratio lower limit index as the local cover layer of the carbonate rock in the research area.

Compared with the prior art, the invention has the beneficial effects that:

the method is different from the traditional qualitative cover layer prediction method, realizes quantitative evaluation of the local dense cover layer on the basis of pre-stack anisotropic parameters and Poisson ratio inversion, guides the storage layer prediction work, provides a basis for subsequent favorable zone division, trap recognition and evaluation and target optimization, improves the local cover layer prediction precision, avoids risks caused by storage conditions, and accordingly improves the drilling success rate.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.