CN112528106A

CN112528106A - Volcanic lithology identification method

Info

Publication number: CN112528106A
Application number: CN201911330967.5A
Authority: CN
Inventors: 仇鹏; 李道清; 王彬; 苏航; 闫利恒; 陈超; 戴灿星; 王泉
Original assignee: Petrochina Co Ltd
Current assignee: Petrochina Co Ltd
Priority date: 2019-12-20
Filing date: 2019-12-20
Publication date: 2021-03-19

Abstract

The invention provides a volcanic lithology identification method. The volcanic lithology identification method comprises the following steps: step S10: collecting conventional logging information of volcanic rocks in a target area, and establishing a standardized database based on the conventional logging information; step S20: selecting a plurality of logging curves sensitive to the lithology of the volcanic rock from a standardized database; step S30: based on a plurality of logging curves, a logging curve intersection chart capable of identifying different volcanic lithologies is drawn, the volcanic lithologies are divided, and the distribution range of the volcanic clastic rocks and/or the volcanic lavas is determined. The technical scheme of the invention provides a method for efficiently and accurately identifying the lithology of the volcanic rock by utilizing conventional well logging data and a classification idea, and the method has high popularization adaptability.

Description

Volcanic lithology identification method

Technical Field

The invention relates to the technical field of oil and gas exploration and development, in particular to a volcanic lithology identification method.

Background

The correct identification of the lithology of the volcanic rock is an important means for reasonably knowing the reservoir and comprehensively evaluating geological characteristics, and has important significance for scientifically developing volcanic facies and volcanic reservoir prediction research and guiding oil and gas exploration, evaluation, development and deployment. Over the years, the problem of great difficulty in identifying the lithology of the volcanic rock based on the conventional well logging scales is a world-level problem. The predecessors also made a great deal of exploration and innovation in the identification aspect of the lithology of the volcanic rock, such as:

1) a method and apparatus for identifying lithology of altered volcanic rock (patent No.: CN102053268A) proposes a method and apparatus for performing volcanic lithology identification by using drilling, logging, well logging and chemical analysis data correlation. The method has clear flow and strong operability, and has the difficulties of extraction of drilling, recording and logging characteristic parameters and information fusion, higher experience requirement and difficult popularization.

2) A method and a device for determining an altered volcanic rock effective reservoir in oil and gas exploration (patent number: CN103616731A) proposes a method and principle for determining an altered volcanic rock effective reservoir established by rock alteration factors and reservoir quality factors, and the difficulty is to calculate the alteration factors of the rock (i.e. to identify whether the volcanic rock is altered). The process is simple, the operation is easy, the method is limited to the identification of the altered volcanic rock, and the cost is relatively high because the full-diameter core is required to be calibrated to be an effective reservoir.

3) A three-dimensional space volcanic lithology recognition method (with the patent number of CN102071928A) provides a method for realizing the three-dimensional space volcanic lithology recognition by utilizing a support vector machine method based on element capture logging, imaging logging information and rock structure information. The effect is good, but the cost is high and the popularization is poor.

4) A lithologic character recognition method for a rock-carbon volcanic oil reservoir (with the patent number of CN104929626A) provides a lithologic character recognition method based on rock debris, a well logging intersection map, lithofacies division and thin slice naming. The method has strong operability and reliable results, but has complex flow, time consumption and large workload.

5) A volcanic lithology recognition method based on electric imaging logging fractal dimension (patent number is CN108830140A) provides a lithology recognition method based on imaging logging data of cored and uncaptured well sections and calculating the fractal dimension. The precision is relatively reliable, but the limitation is large, the cost is high, the technical requirement on operators is high, and the popularization is not strong.

The mature and effective underground volcanic lithology recognition method mainly depends on means such as element capture energy spectrum, chemical measurement (silicon-alkali method), imaging logging, well drilling coring and the like, but for areas with deep layers, large well spacing and fast phase change, the underground volcanic lithology recognition method depending on the means has the problems of high cost and large popularization difficulty, and a set of intersection plate and recognition method which are reasonable in structure, economical, efficient, clear in hierarchy and accurate in recognition are not formed based on conventional logging information. Therefore, on the basis of the understanding before absorption, core outcrop sample calibration, imaging logging characteristic induction and conventional logging characteristic summarization, a method for identifying the lithology of the volcanic rock, which is low in cost, high in efficiency and high in popularization applicability, needs to be provided.

Disclosure of Invention

The invention mainly aims to provide a volcanic lithology identification method, which can be used for efficiently and accurately identifying the volcanic lithology by utilizing conventional well logging information and has higher popularization adaptability.

In order to achieve the above object, the present invention provides a volcanic lithology identification method, including: step S10: collecting conventional logging information of volcanic rocks in a target area, and establishing a standardized database based on the conventional logging information; step S20: selecting a plurality of logging curves sensitive to the lithology of the volcanic rock from a standardized database; step S30: based on a plurality of logging curves, a logging curve intersection chart capable of identifying different volcanic lithologies is drawn, the volcanic lithologies are divided, and the distribution range of the volcanic clastic rocks and/or the volcanic lavas is determined.

Further, when the volcanic lithology is the pyroclastic rock, after step S30, the volcanic lithology identification method further includes: step S40: selecting a plurality of well logs sensitive to the lithology of the pyroclastic rock from the standardized database; step S50: and drawing a logging curve intersection chart capable of identifying different pyroclastic rock lithologies, and dividing the pyroclastic rock lithologies to obtain the pyroclastic rock large category.

Further, after step S50, the volcanic rock lithology identification method further includes: step S60: selecting a plurality of well logs sensitive to lithology of a large class of pyroclastic rock from a standardized database; step S70: and drawing a logging curve intersection chart capable of identifying the lithology of different large types of the pyroclastic rock, and performing subclassification on each lithology of the large types of the pyroclastic rock.

Further, the logging curve intersection chart capable of identifying the lithology of different pyroclastic rocks is a natural gamma and density (GR-DEN) intersection chart.

Further, when the volcanic lithology is volcanic lava, after step S30, the volcanic lithology identification method further includes: step S45: selecting a plurality of well logging curves sensitive to the lithology of the volcanic lava from a standardized database; step S55: and drawing a logging curve intersection chart capable of identifying different lava lithologies, and dividing the lava lithologies to obtain the large lava types.

Further, after step S55, the volcanic rock lithology identification method further includes: step S65: selecting a plurality of well logging curves sensitive to lithology of the volcanic lava major class from a standardized database; step S75: and drawing a well logging curve intersection chart capable of identifying the lithology of different volcanic lavas, and performing subclassification on each lithology of the volcanic lavas.

Further, the well logging curve intersection chart capable of identifying the lithology of different volcanic lavas is an intersection chart of natural gamma rays and undisturbed formation resistivity (GR-RT).

Further, the volcanic lithology identification method further comprises the following steps: step S05: naming the lithology of the volcanic rock based on data obtained in one or more of outcrop exploration, rock core observation, experimental analysis and slice identification modes to obtain a lithology naming database of the volcanic rock; and/or, step S15: and establishing a lithologic property data database of the volcanic rock based on the lithologic property data of the volcanic rock obtained by the imaging logging and/or element capture logging mode.

Further, the volcanic lithology identification method further comprises the following steps: step S80: and (4) comparing the lithology name database of the volcanic rock obtained in the step (S05) and/or the lithology information database of the volcanic rock established in the step (S15) with the lithology of the divided volcanic rock, and judging the accuracy of the volcanic rock lithology identification method for identifying the lithology of the volcanic rock.

Further, the logging curve intersection chart capable of identifying the lithology of different volcanic rocks is an intersection chart of natural gamma rays and undisturbed formation resistivity/sound wave time difference (GR-RT/AC).

By applying the technical scheme of the invention, the lithology of the volcanic rock is identified by drawing an intersection chart of a logging curve sensitive to the lithology response of the volcanic rock on the basis of conventional logging information; the technical scheme of the invention has the advantages of simple operation steps and low cost, eliminates the interference of reservoir structural factors on the volcanic lithology identification, improves the lithology identification accuracy of effective reservoirs, provides a method for quickly, efficiently, low-cost and accurately identifying the complex volcanic lithology by using conventional logging information, and has higher popularization adaptability.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:

FIG. 1 shows a flow diagram of an embodiment of a volcanic lithology identification method according to the present invention;

FIG. 2 is a schematic diagram of the composition of a base database according to an embodiment of the volcanic lithology identification method of the present invention;

FIG. 3 is a hierarchical classification diagram of the lava lithology to be identified in the target area according to the embodiment of the lava lithology identification method of the present invention;

fig. 4 shows a natural gamma and undisturbed formation resistivity/acoustic time difference (GR-RT/AC) intersection map for volcanic clastic-volcanic lithology identification according to an embodiment of the volcanic lithology identification method of the present invention;

FIG. 5 illustrates a natural gamma-density (GR-DEN) intersection plot for volcanic clastic lithology identification in accordance with an embodiment of the volcanic lithology identification method of the present invention;

FIG. 6 shows a convergence plate of natural gamma and undisturbed formation resistivity (GR-RT) for volcanic lava major identification according to an embodiment of the volcanic lithology identification method of the present invention;

FIG. 7 illustrates an intersection plot of acoustic moveout and compensated neutrons (AC-CNL) for fundamental volcanic lithology identification in accordance with an embodiment of the volcanic lithology identification method of the present invention;

FIG. 8 illustrates a natural gamma-density (GR-DEN) junction plot for neutral volcanic lithology identification in accordance with an embodiment of the volcanic lithology identification method of the present invention;

FIG. 9 illustrates a density and sonic time difference (DEN-AC) intersection plate of acidic volcanic lithology identification in accordance with an embodiment of the volcanic lithology identification method of the present invention; and

fig. 10 shows a density and compensated neutron (DEN-CNL) junction version of sub-volcanic lithology identification according to an embodiment of the volcanic lithology identification method of the present invention.

Detailed Description

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.

It is noted that, unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

In the present invention, unless specified to the contrary, use of the terms of orientation such as "upper, lower, top, bottom" or the like, generally refer to the orientation as shown in the drawings, or to the component itself in a vertical, perpendicular, or gravitational orientation; likewise, for ease of understanding and description, "inner and outer" refer to the inner and outer relative to the profile of the components themselves, but the above directional words are not intended to limit the invention.

It should be noted that the volcanic lithology identification method is a method for identifying the volcanic lithology based on conventional well logging information.

It should be noted that, according to the difference of the target area, the lithology of the volcanic rock is different; in the embodiment of the invention, a certain area of the Sinkiang pseudo-Pascal basin is selected as a target area, and the volcanic rock lithology identification method is applied to the target area, and the results are shown in FIGS. 4 to 10.

As shown in fig. 1 to 4, in an embodiment of the present invention, a volcanic lithology identification method includes:

step S10: collecting conventional logging information of volcanic rocks in a target area, and establishing a standardized database based on the conventional logging information;

step S20: selecting a plurality of logging curves sensitive to the lithology of the volcanic rock from the standardized database;

step S30: based on the plurality of logging curves, a logging curve intersection chart capable of identifying different volcanic lithologies is drawn, the volcanic lithologies are divided, and the distribution range of the pyroclastic rock and/or the volcanic lava is determined.

Specifically, step S10 is to collect, arrange, and standardize conventional logging data collected by different logging series, establish a standardized logging data database, that is, collect and arrange conventional logging data collected by different logging series in a target area, standardize the conventional logging data, and establish a standardized logging data database based on the standardized conventional logging data; through the standardized processing of the conventional logging data, the correction of the conventional logging data acquired by different logging series can be realized, the system error can be eliminated, and the lithology identification accuracy can be improved; step S20 is to select a plurality of well logging curves that can identify the lithology of volcanic rocks and have a good identification effect from the standardized well logging information database based on the step S10; step S20, determining a plurality of logging curves which can identify the lithology of the volcanic rock and have relatively good identification effect on the lithology of the volcanic rock by utilizing standardized conventional logging data in the standardized logging data database established in the step S10, and laying a foundation for ensuring that the lithology of the volcanic rock is accurately identified through the logging curves in the subsequent steps; step S30 is to draw an intersection map based on the plurality of well-logging curves for identifying the lithology of the volcanic rock based on step S20, analyze the drawn intersection map of the well-logging curves, and partition distribution areas of different lithologies of the volcanic rock, so as to determine upper and lower limit values of the distribution areas of different lithologies of the volcanic rock and/or establish a linear relational expression of the different lithologies of the volcanic rock.

Further, in step S10, the conventional well logging data is well logging data obtained by a conventional well logging method, where the conventional well logging method mainly refers to 9 conventional well logging curves applied in the field of oil and gas exploration, including natural Gamma (GR), acoustic time difference (AC), Density (DEN), Compensated Neutrons (CNL), natural potential (SP), undisturbed formation Resistivity (RT), invaded zone Resistivity (RI), formation water resistivity (Ro), and borehole diameter (CAL).

It should be noted that the standardized processing procedure of the conventional well logging data is a conventional technical means in the art, and is not described herein.

It should be noted that, in the embodiment of the present invention, the selection of the logging curve sensitive to the lithologic response of the volcanic rock is determined by the sensitive parameter sensitive to the lithologic response of the volcanic rock, and the selection of the sensitive parameter is obtained on the basis of the intersection plate test of a large number of logging curves and combinations thereof, that is, the intersection plate of the logging curves is continuously tried to determine which curve can distinguish the lithologic of the volcanic rock more accurately, and the curve that can distinguish and determine the lithologic of the volcanic rock is determined as the logging curve sensitive to the lithologic response of the volcanic rock.

Specifically, as shown in fig. 4, in the embodiment of the present invention, in step S20, the multiple logging curves sensitive to the lithologic response of the volcanic rock are the natural Gamma (GR), the undisturbed formation Resistivity (RT), and the acoustic time difference (AC) curves, and on the basis of step S20, the intersection map of the logging curves that can identify different lithologies of the volcanic rock drawn in step S30 is the intersection map of the natural gamma and the undisturbed formation resistivity/acoustic time difference (GR-RT/AC).

As shown in fig. 4, a convergence plate of natural gamma and undisturbed formation resistivity/acoustic time difference (GR-RT/AC) is established, wherein the abscissa is the natural gamma value in API, and the ordinate is the ratio of undisturbed formation resistivity to acoustic time difference in (Ω · m)/(μ s/ft); analyzing and dividing lithologic distribution areas of the pyroclastic rock and the volcanic lava; respectively determining the upper limit value and the lower limit value of the respective distribution area, and/or establishing a linear relation according to the requirement; according to the steps, the volcanic lithology is divided into a large class, the volcanic lithology is divided into the pyroclastic rock and the volcanic lava by utilizing the natural gamma and undisturbed formation resistivity/sound wave time difference (GR-RT/AC) intersection chart, and distribution areas of the pyroclastic rock and the volcanic lava are divided; determining the upper limit value and the lower limit value of the distribution area of the pyroclastic rock and the volcanic lava respectively, and/or establishing the linear relation of the pyroclastic rock and the volcanic lava respectively according to the requirement.

According to the technical scheme, the method for identifying the lithology of the volcanic rock based on the conventional logging information is provided, and specifically, the lithology of the volcanic rock is identified by drawing an intersection chart of a logging curve sensitive to the lithology response of the volcanic rock on the basis of the conventional logging information; the method can be used for rapidly identifying the lithology of the volcanic rock by establishing the volcanic rock lithology identification chart in the well section without coring, without special well logging and with a conventional well logging curve, has the advantages of simple operation steps and low cost, eliminates the interference of reservoir structural factors on the volcanic rock lithology identification, improves the accuracy of lithology identification of an effective reservoir, provides a method for rapidly, efficiently, inexpensively and accurately identifying the lithology of the complex volcanic rock by using conventional well logging information, and has high popularization adaptability.

It should be noted that when it is determined that the lithology of volcanic rock is the pyroclastic rock and the volcanic lava, there is no precedence for further identifying the lithology of the pyroclastic rock and the lithology of the volcanic lava, and the identification of the lithology of the pyroclastic rock or the lithology of the volcanic lava can be performed first according to actual conditions and actual needs.

Preferably, as shown in fig. 1 and fig. 2, in an embodiment of the present invention, when the volcanic rock lithology is pyroclastic rock, after step S30, the volcanic rock lithology identification method further includes:

step S40: selecting a plurality of well logs sensitive to the lithology of the pyroclastic rock from the standardized database;

step S50: and drawing a logging curve intersection chart capable of identifying different pyroclastic rock lithologies, and dividing the pyroclastic rock lithologies to obtain the pyroclastic rock large category.

Specifically, through step S30, the volcanic lithology is divided, and distribution areas of different volcanic lithologies and upper and lower limit values of the respective distribution areas are determined; when the lithology of the volcanic rock contains the pyroclastic rock, determining the upper limit value and the lower limit value of the distribution area of the pyroclastic rock through the step S30, establishing a logging curve intersection plate on the basis of the step S30, and dividing the lithology of the pyroclastic rock to obtain the large class of the pyroclastic rock; more specifically, in step S30, in step S40, a plurality of well logs that can identify the large class of the pyroclastic rock and have a good identification effect are selected from the standardized well log database; step S40, by utilizing standardized conventional logging data in the standardized logging data database, determining a plurality of logging curves which can identify the large class of the pyroclastic rock and have relatively good identification effect on the large class of the pyroclastic rock, and laying a foundation for ensuring that the large class of the pyroclastic rock is accurately identified through the logging curves in the subsequent steps; step S50 is to, on the basis of step S40, draw a convergence chart based on the plurality of well logs in combination with the distribution region of the pyroclastic rock determined in step S30, to identify the lithology of the pyroclastic rock, partition the distribution regions of different lithologies of the pyroclastic rock, i.e., partition the distribution regions of the large types of the pyroclastic rock, and further determine the upper and lower limit values of the respective distribution regions and/or establish respective linear relations.

In the technical scheme, the lithology of each major type of volcanic rock is identified by drawing an intersection chart of a logging curve sensitive to lithology response of each major type of volcanic rock on the basis of conventional logging information and in combination with the distribution area of each major type of volcanic rock determined in the step S30, so that the operation steps are simple and the cost is low; on the basis of the steps S10 to S30, the invention also provides a thought for identifying the lithology of the volcanic rocks in a grading and classifying manner, the lithology of the volcanic rocks is firstly classified into a large class by drawing a logging curve intersection plate, the distribution range of each large class of the volcanic rocks is determined according to the divided distribution region of each large class of the volcanic rocks, on the basis, the logging curve intersection plate of each large class of the volcanic rocks is respectively drawn aiming at each determined large class of the volcanic rocks, the distribution region of the lithology of each large class is divided to determine the distribution range of the lithology of each large class, and the rapid identification of the lithology of each large class of the volcanic rocks is realized; the train volcanic rock lithology recognition method is reasonable in structure and clear in hierarchy, through the steps, the lithology of various kinds of volcanic rocks can be recognized quickly, efficiently and accurately, and the method has high popularization adaptability.

Specifically, as shown in fig. 5, in the embodiment of the present invention, in step S40, the plurality of well logs sensitive to the lithologic response of the pyroclastic rock are natural Gamma (GR) and Density (DEN) curves, and on the basis of step S40, the well log intersection map drawn in step S50, which is capable of identifying the lithologic response of different pyroclastic rocks, is an intersection map of natural gamma and density (GR-DEN).

As shown in fig. 5, according to the distribution value range (i.e., the distribution region and the distribution range) of the pyroclastic rock divided in step S30, a convergence map of natural gamma and density (GR-DEN) is created, wherein the abscissa is the natural gamma value in API, and the ordinate is the density value in unitIs g/cm³(ii) a Analyzing and dividing the area of the large-class distribution of the pyroclastic rock; respectively determining the upper limit value and the lower limit value of the distribution area of the large volcaniclastic rock, and/or establishing a linear relation according to the requirement; performing large-class classification on the lithology of the pyroclastic rock through the steps, dividing the lithology of the pyroclastic rock into tuff mudstone and tuff sandstone by utilizing the natural gamma and density (GR-DEN) intersection chart, and dividing distribution areas of the tuff mudstone and the tuff sandstone; determining the upper limit value and the lower limit value of the distribution area of the tufty mudstone and the tufty sandstone respectively, and/or establishing the linear relation of the tufty mudstone and the tufty sandstone according to the requirement.

According to the technical scheme, the conventional logging information is used as a basis, the distribution area of the pyroclastic rock is determined in the step S30, and the lithology of the pyroclastic rock is identified by drawing the intersection chart of the logging curve sensitive to the lithology response of the pyroclastic rock.

It should be noted that, when the pyroclastic rock class is divided in step S50, whether a new intersection chart needs to be established to further divide the volcanic lithology of the first level of the pyroclastic rock class can be determined according to the distribution value range of the divided pyroclastic rock class.

Preferably, as shown in fig. 1 to 5, in an embodiment of the present invention, after step S50, the volcanic rock lithology identification method further includes:

step S60: selecting a plurality of well logs sensitive to lithology of a large class of pyroclastic rock from a standardized database;

step S70: and drawing a logging curve intersection chart capable of identifying the lithology of different large types of the pyroclastic rock, and performing subclassification on each lithology of the large types of the pyroclastic rock.

Specifically, through step S50, the lithology of the pyroclastic rock is divided to obtain the large class of the pyroclastic rock, and the distribution area of each large class of the pyroclastic rock and the upper and lower limit values of the distribution area of each large class are determined; in step S60, based on step S50, a plurality of well logging curves that can identify the lithology of each of the major types of pyroclastic rock and have a good identification effect are selected from the standardized well logging information database; step S60, conventional logging data in the standardized logging data database are utilized to determine a plurality of logging curves which can identify the lithology of each large class of the volcaniclastic rock and have relatively good identification effect on the lithology of each large class of the volcaniclastic rock, and a foundation is laid for ensuring that the lithology of each large class of the volcaniclastic rock is accurately identified through the logging curves in the subsequent steps; step S70 is to, on the basis of step S60, draw an intersection map based on the plurality of well logging curves in combination with the distribution area of each of the large types of the pyroclastic rock determined in step S50, to identify the lithology of each of the large types of the pyroclastic rock, partition the distribution area of the lithology of each of the large types of the pyroclastic rock by analyzing the drawn intersection map of the well logging curves, and further determine the upper and lower limit values of the distribution area and/or establish a linear relational expression.

In the technical scheme, the lithology of each large class of the pyroclastic rock is identified by drawing an intersection chart of a logging curve sensitive to the lithology response of each large class of the pyroclastic rock on the basis of conventional logging information and in combination with the distribution area of the large class of the pyroclastic rock determined in the step S50, so that the operation steps are simple and the cost is low; on the basis of the step S40 and the step S50, the method utilizes the idea of identifying the lithology of the volcanic rock by classification and quickly divides the distribution area of the lithology of each large class of the volcanic clastic rock by drawing a well logging curve intersection plate so as to determine the distribution range of the lithology of each large class of the volcanic clastic rock and realize the quick identification of the lithology of each large class of the volcanic clastic rock. Through the steps, the lithology of each large class of the volcaniclastic rocks can be rapidly, efficiently and accurately identified, and the method has high popularization adaptability.

It should be noted that there is no precedence in identifying the lithology of each of the major types of pyroclastic rock.

Preferably, as shown in fig. 1 to 4 and 6, in an embodiment of the present invention, when the volcanic lithology is volcanic lava, after step S30, the volcanic lithology identification method further includes:

step S45: selecting a plurality of well logging curves sensitive to the lithology of the volcanic lava from a standardized database;

step S55: and drawing a logging curve intersection chart capable of identifying different lava lithologies, and dividing the lava lithologies to obtain the large lava types.

Specifically, through step S30, the volcanic lithology is classified into a large category, and distribution areas of different volcanic lithologies and upper and lower limit values of the distribution areas are determined; when the lithology of the volcanic lava contains the volcanic lava, determining the upper limit value and the lower limit value of the distribution area of the volcanic lava through the step S30, establishing a logging curve intersection plate on the basis of the step S30, and performing large-class division on the lithology of the volcanic lava to obtain a large class of the volcanic lava; more specifically, in step S30, in step S45, a plurality of well logging curves that can identify the volcanic lava major category and have a good identification effect are selected from the standardized well logging data database; step S45, by utilizing standardized conventional logging data in the standardized logging data database, determining a plurality of logging curves which can identify the large volcanic lava and have relatively good identification effect on the large volcanic lava, and laying a foundation for ensuring that the large volcanic lava is accurately identified through the logging curves in the subsequent steps; step S55 is to, on the basis of step S45, draw an intersection map based on the plurality of logging curves in combination with the distribution region of the lava determined in step S30 to identify the lithology of the lava, analyze the drawn intersection map of the logging curves, and partition distribution regions of different lava lithologies, that is, partition a distribution region of a large category of lava and upper and lower limit values of the distribution region and/or establish respective linear relational expressions.

In the technical scheme, the lithology of each large type of volcanic rock is identified by drawing an intersection chart of a logging curve sensitive to the lithology response of each large type of volcanic rock on the basis of conventional logging information and in combination with the distribution area of each large type of volcanic rock determined in the step S30, so that the operation steps are simple and the cost is low; on the basis of the steps S10 to S30, the invention also provides a thought for identifying the lithology of the volcanic rocks in a grading and classifying manner, the lithology of the volcanic rocks is firstly classified into a large class by drawing a logging curve intersection plate, the distribution range of each large class of the volcanic rocks is determined according to the divided distribution region of each large class of the volcanic rocks, on the basis, the logging curve intersection plate of each large class of the volcanic rocks is respectively drawn aiming at each determined large class of the volcanic rocks, the distribution region of the lithology of each large class is divided to determine the distribution range of the lithology of each large class, and the rapid identification of the lithology of each large class of the volcanic rocks is realized; the train volcanic rock lithology recognition method is reasonable in structure and clear in hierarchy, through the steps, the lithology of various kinds of volcanic rocks can be recognized quickly, efficiently and accurately, and the method has high popularization adaptability.

Specifically, as shown in fig. 6, in the embodiment of the present invention, in step S45, the plurality of logging curves sensitive to the lava lithology response are selected as the natural Gamma (GR) and the undisturbed formation Resistivity (RT), and on the basis of step S45, the logging curve intersection map drawn in step S55 capable of identifying different lava lithologies is the intersection map of the natural gamma and the undisturbed formation resistivity (GR-RT).

As shown in fig. 6, according to the distribution value domain of the lava divided in step S30, establishing an intersection chart of natural gamma and undisturbed formation resistivity (GR-RT), wherein the abscissa is the natural gamma value in unit of API, and the ordinate is the undisturbed formation resistivity value in unit of Ω · m; analyzing and dividing the area of volcanic lava mass distribution (partially overlapped due to the existence of a transition zone of a matrix); respectively determining the upper limit value and the lower limit value of the distribution area of the volcanic lava and/or establishing a linear relation according to the requirement; performing large-class classification on the lithology of the lava, dividing the lava into basic lava, neutral lava, acidic lava and secondary lava by using the intersection chart of the natural gamma ray and the resistivity (GR-RT) of the undisturbed stratum, and dividing distribution areas of the basic lava, the neutral lava, the acidic lava and the secondary lava; determining the upper limit value and the lower limit value of the distribution area of the basic volcanic rock, the neutral volcanic rock, the acid volcanic rock and the secondary volcanic rock, and/or establishing the linear relation of the basic volcanic rock, the neutral volcanic rock, the acid volcanic rock and the secondary volcanic rock according to the requirement.

According to the technical scheme, the lava lithology is identified by drawing the intersection chart of the logging curve sensitive to the lava lithology response based on the conventional logging information and by combining the distribution area of the lava determined in the step S30, the operation steps are simple, the cost is low, and the lava lithology can be identified quickly, efficiently and accurately.

It should be noted that, when the lava major categories (i.e., the basic lava, the neutral lava, the acidic lava, and the sub lava) are divided in step S55, whether a new intersection chart needs to be established to further divide the lava properties of the next-level lava, such as the basic lava, the neutral lava, the acidic lava, and the sub lava, may be determined according to the distribution value range of the divided lava major categories.

Preferably, as shown in fig. 1 to 4 and 6 to 10, in an embodiment of the present invention, after step S55, the volcanic rock lithology identification method further includes:

step S65: selecting a plurality of well logging curves sensitive to lithology of the volcanic lava major class from a standardized database;

step S75: and drawing a well logging curve intersection chart capable of identifying the lithology of different volcanic lavas, and performing subclassification on each lithology of the volcanic lavas.

Specifically, in step S55, the lithology of the lava is divided to obtain the major categories of lava (i.e., basic lava, neutral lava, acidic lava, and secondary lava), and the distribution areas of the major categories of lava and the upper and lower limit values of the distribution areas of the major categories are determined; based on the step S55, step S65 is to select a plurality of well logging curves from the standardized well logging information database, wherein the well logging curves can identify the lithology of each of the major types of lava rock in the volcanic and have a good identification effect; step S65, by utilizing standardized conventional logging data in the standardized logging data database, determining a plurality of logging curves which can identify the lithology of the volcanic lava and have relatively good identification effect on the lithology of the volcanic lava, and laying a foundation for ensuring that the lithology of the volcanic lava in the subsequent steps is accurately identified through the logging curves; step S75 is to draw an intersection plate based on the plurality of well logging curves for identifying lithology of each large class of the lava based on the distribution area of each large class of the lava determined in step S55 based on step S65, to mark out the distribution area of lithology of each large class of the lava by the intersection plate of the well logging curves respectively drawn, and to further determine upper and lower limit values of the distribution area and/or to establish a linear relation.

In the technical scheme, the lithology of each large class of the volcanic lava is identified by drawing an intersection chart of a logging curve sensitive to lithology response of each large class of the volcanic lava based on conventional logging information and by combining the distribution area of the large class of the volcanic lava determined in the step S55, so that the operation steps are simple and the cost is low; on the basis of the step S45 and the step S55, the method utilizes the idea of identifying the lithology of the volcanic rocks by classification and quickly divides the distribution area of the lithology of each large class of the volcanic lava by drawing a well logging curve intersection plate so as to determine the distribution range of the lithology of each large class of the volcanic lava and realize the quick identification of the lithology of each large class of the volcanic lava. Through the steps, the lithology of various large volcanic lava can be rapidly, efficiently and accurately identified, and the method has high popularization adaptability.

It should be noted that there is no precedence order in identifying the lithology of each of the major categories of volcanic lava.

Specifically, when the lithology of the lava is determined (that is, the lava is determined to be the basic lava, the neutral lava, the acidic lava and the secondary lava), there is no sequence for further identifying the lithology of each of the large lava, and the lithology of the basic lava, the neutral lava, the acidic lava or the secondary lava can be selected to be identified according to actual conditions and actual needs.

Specifically, as shown in fig. 7, in the embodiment of the present invention, in step S65, the multiple well logs sensitive to the lithologic response of the basic volcanic rock are selected as an acoustic time difference (AC) and a Compensation Neutron (CNL), and on the basis of step S65, the well log intersection map rendered in step S75 capable of identifying different lithologies of the basic volcanic rock is an acoustic time difference and compensation neutron (AC-CNL) intersection map.

Judging whether the basic volcanic rock is further identified according to the divided distribution value domain of the basic volcanic rock, and establishing an acoustic wave time difference and compensation neutron (AC-CNL) intersection chart, wherein the horizontal coordinate is an acoustic wave time difference value, the unit is mu s/ft, the vertical coordinate is a compensation neutron value, and the compensation neutron value is a percentage; analyzing and dividing the region of the lithologic distribution of the basic volcanic rock; respectively determining the upper limit value and the lower limit value of the respective distribution area of various basic volcanic rocks, and/or establishing a linear relation according to the requirement; through the steps, classification is carried out on the lithology of the basic volcanic rock, the lithology of the basic volcanic rock is divided into basalt, almond-shaped basalt and basalt volcanic breccia by utilizing the acoustic time difference and a compensated neutron (AC-CNL) intersection chart, distribution areas of the basalt, the almond-shaped basalt and the basalt volcanic breccia are divided, upper limit values and lower limit values of the respective distribution areas are determined, and/or respective linear relational expressions are established according to requirements.

According to the technical scheme, the lithology of the basic volcanic rock is identified by drawing an intersection chart of a logging curve sensitive to the lithology response of the basic volcanic rock on the basis of conventional logging information and in combination with the distribution area of the basic volcanic rock determined in the step S55, the operation steps are simple, the cost is low, and the lithology of the basic volcanic rock can be identified quickly, efficiently and accurately.

Specifically, as shown in fig. 8, in the embodiment of the present invention, in step S65, the plurality of logging curves sensitive to the lithologic response of the neutral volcanic rock are selected as natural Gamma (GR) and Density (DEN), and on the basis of step S65, the logging curve intersection map drawn in step S75, which is capable of identifying the lithologic response of different neutral volcanic rocks, is a natural gamma and density (GR-DEN) intersection map.

Judging to further identify the neutral volcanic rock according to the divided distribution value range of the neutral volcanic rock, and establishing a natural gamma and density (GR-DEN) intersection chart, wherein the abscissa is the natural gamma value and the unit is API, the ordinate is the density value and the unit is g/cm³(ii) a Analyzing and dividing the lithologic distribution area of the neutral volcanic rock; respectively determining the upper limit value and the lower limit value of the distribution area of each neutral volcanic rock, and/or establishing a linear relation according to the requirement; through the steps, subclassification is carried out on the lithology of the neutral volcanic rocks, the lithology of the neutral volcanic rocks is divided into andesite rocks, fusion tuff rocks and andesite volcanic breccid rocks by utilizing the natural gamma and density (GR-DEN) intersection chart, distribution areas of the andesite rocks, the fusion tuff rocks and the andesite volcanic breccid rocks are divided, the upper limit value and the lower limit value of each distribution area are determined, and/or linear relational expressions of each distribution area are established according to requirements.

According to the technical scheme, the lithology of the neutral volcanic rock is identified by drawing an intersection chart of a logging curve sensitive to the lithology response of the neutral volcanic rock based on conventional logging information and in combination with the distribution area of the neutral volcanic rock determined in the step S55, the operation steps are simple, the cost is low, and the lithology of the neutral volcanic rock can be identified quickly, efficiently and accurately.

Specifically, as shown in fig. 9, in the embodiment of the present invention, in step S65, the plurality of well logs sensitive to the acidic volcanic lithologic response are selected as Density (DEN) and sonic time difference (AC), and on the basis of step S65, the well log intersection map rendered in step S75 capable of identifying different acidic volcanic lithologies is density-sonic time difference (DEN-AC) intersection map.

Judging to further identify the acid volcanic rock according to the divided distribution value range of the acid volcanic rock, and establishing a density and sound wave time difference (DEN-AC) intersection chart, wherein the abscissa is a density value and the unit is g/cm³The ordinate is the sound wave time difference value with the unit of mu s/ft; analyzing and dividing the region of the lithologic distribution of the acidic volcanic rock; respectively determining the upper limit value and the lower limit value of the distribution area of each acid volcanic rock, and/or establishing a linear relation according to the requirement; through the steps, the lithology of the acidic volcanic rock is divided into subclasses, the density and sound wave time difference (DEN-AC) intersection chart is utilized to divide the lithology of the acidic volcanic rock into imperial rock, rhyolite, fractured rhyolite, acidic tuff and rhyolite, and the lithology of the acidic volcanic rock is divided into imperial rock, rhyolite, fractured rhyolite, acidic tuff and rhyoliteThe distribution areas of the Enganlite, the rhyolite, the fractured rhyolite, the acid tuff and the fluid volcanic breccia are divided, the upper limit value and the lower limit value of each distribution area are determined, and/or each linear relation is established according to the requirement.

According to the technical scheme, the lithology of the acidic volcanic rock is identified by drawing an intersection chart of a logging curve sensitive to the lithology response of the acidic volcanic rock based on conventional logging information and in combination with the distribution area of the acidic volcanic rock determined in the step S55, the operation steps are simple, the cost is low, and the lithology of the acidic volcanic rock can be identified quickly, efficiently and accurately.

Specifically, as shown in fig. 10, in the embodiment of the present invention, in step S65, the plurality of well logs sensitive to the sub-volcanic lithologic response are Compensation Neutrons (CNL) and Density (DEN), and on the basis of step S65, the well log intersection map that is drawn in step S75 and is capable of identifying the different sub-volcanic lithologies is the compensation neutron-density (CNL-DEN) intersection map.

According to the divided distribution value range of the secondary volcanic rocks, further identification of the secondary volcanic rocks is judged, and a compensation neutron and density (CNL-DEN) intersection chart is established, wherein the abscissa is a compensation neutron value, the compensation neutron value is a percentage, the ordinate is density, and the unit is g/cm³(ii) a Analyzing and dividing the distribution area of the lithology of the secondary volcanic rocks; respectively determining the upper limit value and the lower limit value of the distribution area of each secondary volcanic rock, and/or establishing a linear relation according to the requirement; by the above steps, subclassification is performed on the lithology of the secondary volcanic rock, the lithology of the secondary volcanic rock is divided into the epingythite, the dilongite, the keatite and the fractured epingythite by using the density and compensated neutron (DEN-CNL) intersection chart, distribution areas of the epingythite, the dilongite, the keatite and the fractured epingythite are divided, upper and lower limit values of the respective distribution areas are determined, and/or respective linear relations are established as required.

According to the technical scheme, the secondary volcanic lithology is identified by drawing the intersection chart of the logging curve sensitive to the secondary volcanic lithology response based on the conventional logging information and in combination with the distribution area of the secondary volcanic determined in the step S55, the operation steps are simple, the cost is low, and the secondary volcanic lithology can be identified quickly, efficiently and accurately.

As shown in fig. 3, 4, and 7 to 9, the volcanic lithology recognition method for recognizing the lithology of volcanic rocks based on conventional logging information according to the embodiment of the present invention has a good recognition effect on the full-sequence lithology categories of the basic volcanic rocks, the neutral volcanic rocks, and the acidic volcanic rocks, and can also effectively distinguish the volcanic corneites containing the basic matrixes and the neutral matrixes, thereby eliminating the influence of complex naming of the volcanic rocks due to the different matrixes, and improving the lithology recognition accuracy of the effective reservoir.

The invention relates to a volcanic lithology recognition method based on conventional logging scales, which is used for establishing a set of method for quickly, inexpensively and efficiently recognizing the volcanic lithology by using conventional logging information and has a good recognition effect on volcanic breccia containing base, medium and acidic matrix.

Preferably, as shown in fig. 1 and fig. 2, in an embodiment of the present invention, the volcanic rock lithology identification method further includes the following steps:

step S05: naming the lithology of the volcanic rock based on data obtained in one or more of outcrop exploration, rock core observation, experimental analysis and slice identification modes to obtain a lithology naming database of the volcanic rock; and

step S15: and establishing a volcanic lithology data database based on volcanic lithology data obtained by special logging methods such as imaging logging and/or element capture.

Specifically, step S05 is to collect and sort the data after outcrop survey, core observation, experimental analysis, and slice identification, and establish a regional (secondary structure or basin category) standard volcanic lithology naming database based on the basic research information (or data).

That is, in step S05, data (or basic research information) obtained by one or more of outcrop survey, core observation, experimental analysis, and slice identification methods are collected and collated in the target area, and then, based on the data, the lithology of the volcanic rock in the target area is named, and a standardized lithology naming database of the volcanic rock is created.

Further, in step S05, the name or classification of the lithology of the volcanic rock is to be in accordance with the national standard or the industry standard issued by the national authority (e.g., the geologic and mining department, the middle oil industry association, etc.). Therefore, according to the national standard and the industrial standard issued by the national authority department, the unified naming of the lithology of the volcanic rock in the target area can be realized, the influence of the complex naming of the volcanic rock caused by different matrixes and different internal structural characteristics is eliminated, and the lithology identification accuracy is improved.

Further, in the embodiment of the present invention, in step S05, a lithology naming database of volcanic rocks standardized by the regional (secondary structure or basin domain) based on the basic research information is established. That is, in the national standard and the industrial standard issued by the national authority, the standard naming of the volcanic rock lithology in a partial region (such as a secondary structure or a basin region) is selected as the standard naming of the volcanic rock lithology in the target region, so that the standard naming range for naming the lithology of the volcanic rock in the target region can be narrowed, the workload is reduced, the working efficiency is improved, and the non-standardization of the volcanic rock lithology naming of the target region is avoided.

Specifically, step S15 is to collect and sort the volcanic lithology information picked up and identified by the special logging (mainly imaging logging), to establish a volcanic information base based on the special logging identification, that is, to collect and sort the volcanic lithology information picked up and identified by the special logging method (mainly imaging logging) in the target area, and to establish a volcanic lithology information database (that is, volcanic information base) based on the special logging method identification.

The method can be realized by establishing the lithology naming database of the volcanic rock and the lithology information database of the volcanic rock, and aiming at the geological characteristics of a research work area (namely a target area), determining the lithology type to be identified, namely determining the lithology type of the volcanic rock of the target area according to the lithology information of the volcanic rock obtained by special well logging methods such as outcrop head reconnaissance, rock core observation, experimental analysis, slice identification mode, imaging well logging, element capture and the like of the target area, and further determining the lithology type of the volcanic rock to be identified of the target area; according to the national standard and the industrial standard issued by the national authority department, the rock property categories of the volcanic rocks needing to be identified in the target area are uniformly named, the influence of complex naming caused by the fact that the volcanic rocks contain different matrixes and different internal structural characteristics is eliminated, and the lithological identification accuracy is improved.

Further, as shown in fig. 2, in the embodiment of the present invention, through steps S10, S05 and S15, a standardized logging information database, a lithology naming database of volcanic rock and a lithology information database of volcanic rock are established, and a unified database (i.e., the basic database in fig. 2) formed by the above three databases is established.

Further, in the embodiment of the present invention, by comparing the three databases, a logging project (i.e. a logging curve) sensitive to volcanic lithological response is preferred; specifically, for the lithology of the volcanic rock in the same well depth of the target area, the lithology of the volcanic rock can be identified through a lithology name database of the volcanic rock and a lithology data database of the volcanic rock, and simultaneously identified through a logging curve in a standardized logging data database, the lithology of the volcanic rock identified through the three databases is compared, and when the lithology of the volcanic rock identified through the logging curve in the standardized logging data database is consistent with or close to the lithology of the volcanic rock identified through the lithology name database of the volcanic rock and the lithology data database of the volcanic rock, the logging curve in the standardized logging data database is a preferable logging curve sensitive to the lithology response of the volcanic rock.

In the setting, the lithology type of the volcanic rock to be identified in the target area can be determined through the lithology naming database of the volcanic rock and the lithology information database of the volcanic rock, the unified naming of the lithology type of the volcanic rock to be identified, which meets the national standard and the industry standard issued by the national authority department, can be carried out, and the influence of complex naming of the volcanic rock due to the fact that the volcanic rock contains different matrixes and different internal structural characteristics can be eliminated; the method has the advantages that the volcanic lithology intersection chart is established by utilizing the idea of identifying the volcanic lithology through classification and classification through the standardized logging data database, the volcanic lithology intersection chart is quickly identified, the interference of reservoir structural factors on the volcanic lithology identification is eliminated, and the accuracy of lithology identification of effective reservoirs is improved.

Of course, in an alternative embodiment not shown in the drawings, the volcanic rock lithology identification method of the present invention may further include the following steps according to actual conditions and actual needs:

step S05: naming the lithology of the volcanic rock based on data obtained in one or more of outcrop exploration, rock core observation, experimental analysis and slice identification modes to obtain a lithology naming database of the volcanic rock; or the like, or, alternatively,

Preferably, as shown in fig. 1 and fig. 2, in an embodiment of the present invention, the volcanic rock lithology identification method further includes:

step S80: and comparing the lithology name database of the volcanic rock obtained in the step S05 with the lithology information database of the volcanic rock established in the step S15 with the lithology of the divided volcanic rock, and judging the accuracy of the volcanic rock lithology identification method for identifying the lithology of the volcanic rock.

Specifically, as shown in fig. 2 to 10, in an embodiment of the present invention, fig. 3 is a volcanic rock lithology category of a target area determined according to data in the lithology naming database and the lithology data database in the base database in fig. 2, that is, the volcanic rock lithology category that the target area needs to identify; fig. 4 to 10 are views showing the volcanic lithology categories of the target region identified by the volcanic lithology identification method according to the present invention based on the data in the logging data database in the basic database of fig. 2.

In the above technical solution, the accuracy of the volcanic lithology recognition method of the present invention for volcanic rock can be obtained by comparing the volcanic lithology categories of the target area recognized in fig. 4 to fig. 10 with the determined volcanic lithology categories of the target area to be recognized in fig. 3. According to the embodiment of the invention, the volcanic lithology identification method has higher accuracy in identifying the volcanic lithology. The identification method can be applied to other areas needing lithology identification.

Further, it can be inferred that the establishment of the standardized logging information database, the volcanic lithology naming database, the volcanic lithology information database and the basic database is one of the necessary conditions for improving the identification accuracy adaptability of the volcanic lithology identification method of the present invention, and the volcanic lithology identification method of the present invention is still applicable to exploration new areas without the volcanic lithology naming database and/or the volcanic lithology information database, and has high popularization adaptability.

Of course, in an alternative embodiment not shown in the attached drawings, according to actual situations and actual needs, the volcanic lithology identification method of the present invention further includes:

step S80: and comparing the lithology name database of the volcanic rock obtained in the step S05 or the lithology information database of the volcanic rock established in the step S15 with the lithology of the divided volcanic rock, and judging the accuracy of the volcanic rock lithology identification method for identifying the lithology of the volcanic rock.

The operation of the present invention will be described in detail with reference to fig. 1 to 10.

The volcanic lithology identification method disclosed by the invention has the following design ideas:

1. determining lithology categories to be identified aiming at geological features of a research work area;

2. establishing various large lithologic intersection charts by classification based on conventional logging data;

3. and establishing a next grade lithology intersection chart of each large lithology on the basis of the large lithology identification.

Furthermore, the data of 9 conventional logging curves may be collected from a plurality of logging series and interfered by different environments, and the data needs to be subjected to system error correction before the method is applied, wherein the system error correction of the data is one of necessary conditions for guaranteeing the specification of the method; it should be noted that the technical key points and processing procedures for correcting the system error are conventional technical means in the art, and are not described herein again.

Wherein, the classification of the general lithology mainly comprises the following steps: pozzolanic mudstones of the pyroclastic rock class, pozzolanic sandstones, and foundries of the volcanic class, neutrality, acidity, sub-volcanic (invasive lithology), and the like. The classification of the lithology major categories is shown in fig. 3.

Further, the second-order lithologic intersection plate includes pyroclastic rock, basic volcanic rock, neutral volcanic rock, acidic volcanic rock, and second-order lithologic (intruding lithology) intersection plates, as shown in fig. 4 to 10. It should be noted that the lithological division limit value determined by each primary lithological intersection plate is different due to different regions and differences in volcanic eruption time, stage, scale, duration and strength, and various volcanic rocks have different properties.

The volcanic lithology identification method has the following beneficial effects:

1. the method firstly carries out the classification of the large category on various lithologies, simplifies the lithology category and solves the problem of complex lithology category;

2. the method utilizes the concept of hierarchical classification progressive (namely hierarchical classification) to classify lithology into large classes for intersection plate identification, and then gradually identifies small classes of intersection plates, so that volcanic lava such as basic, neutral, acidic and sub-volcanic rocks and small classes of lithology thereof can be identified, and complex lithology such as volcanic breccia containing basic, medium and acidic matrixes can be distinguished;

3. the lithology recognition chart plate established by the invention can quickly, low-cost and efficiently recognize the lithology of volcanic rock, and solves the problems of complex lithology, poor recognition precision of a single chart plate and the like.

According to the above design concept, the specific operation of the embodiment of the present invention is as follows:

step S05: naming the lithology of the volcanic rock based on data obtained in one or more of outcrop exploration, rock core observation, experimental analysis and slice identification modes to obtain a lithology naming database of the volcanic rock;

step S15: establishing a lithologic property data database of the volcanic rock based on the lithologic property data of the volcanic rock obtained by special well logging methods such as imaging well logging and/or element capture;

as shown in fig. 3, the lithology type of the volcanic rock to be identified in the target area can be determined through the established lithology naming database of the volcanic rock and the lithology data database of the volcanic rock, and the division of the lithology type of the volcanic rock is in accordance with the national standard and the industry standard issued by the national authority department, and the lithology type of the volcanic rock to be identified in the target area is named uniformly according to the national standard and the industry standard.

Step S10: collecting conventional logging information of volcanic rocks in a target area, and establishing a standardized logging information database based on the conventional logging information;

establishing a lithologic naming database of the volcanic rock, a lithologic data database of the volcanic rock and a standardized logging data database through the steps of S05, S15 and S10, and establishing a unified database (namely, a basic database in FIG. 2) formed by the three databases;

by comparing the lithology naming database of the volcanic rock, the lithology information database of the volcanic rock and the standardized logging information database, a logging curve sensitive to the lithology response of the volcanic rock is optimized.

Step S20: selecting a plurality of logging curves sensitive to the lithology of the volcanic rock from the standardized logging data database;

step S30: drawing a logging curve intersection chart capable of identifying different volcanic lithologies based on the plurality of logging curves, dividing the volcanic lithologies, and determining the distribution range of the pyroclastic rock and/or the volcanic lava;

as shown in fig. 4, an intersection chart of natural gamma and undisturbed formation resistivity/acoustic time difference (GR-RT/AC) is established, the lithology of volcanic rock is divided into pyroclastic rock and volcanic lava, distribution regions of the pyroclastic rock and the volcanic lava are divided, upper and lower limit values of the respective distribution regions are determined, and respective distribution value regions are determined.

(Note that there is no order in the following description of the identification of lithology of pyroclastic rock and volcanic lava)

step S50: drawing a logging curve intersection chart capable of identifying different pyroclastic rock lithologies, and dividing the pyroclastic rock lithologies to obtain a pyroclastic rock large class;

as shown in fig. 5, an intersection map of natural gamma and density (GR-DEN) is established, the pyroclastic rock lithology is divided into tuff mudstone and tuff, distribution regions of the tuff mudstone and the tuff sandstone are divided, upper and lower limit values of the respective distribution regions are determined, and respective distribution value domains are determined.

As shown in fig. 6, an intersection map of natural gamma rays and undisturbed formation resistivity (GR-RT) is established, the lava lithology is divided into basic lava, neutral lava, acidic lava and sub lava, distribution regions of the basic lava, the neutral lava, the acidic lava and the sub lava are divided, upper and lower limit values of the respective distribution regions are determined, and respective distribution value regions are determined.

(Note that there is no order in the following description for identifying lithology of each of the major volcanic lava rock types)

step S75: drawing a well logging curve intersection chart capable of identifying the lithology of different volcanic lavas, and performing subclassification on each lithology of the volcanic lavas;

as shown in fig. 7, an acoustic time difference and compensated neutron (AC-CNL) intersection chart is established, the lithology of the basic volcanic rock is divided into subclasses, the lithology of the basic volcanic rock is divided into basalt, almond-shaped basalt and basalt volcanic kerbstone, the distribution regions of the basalt, the almond-shaped basalt and the basalt volcanic kerbstone are divided, the upper limit value and the lower limit value of each distribution region are determined, and each distribution value region is determined.

As shown in fig. 8, a natural gamma-density (GR-DEN) intersection map is established, the lithology of the neutral volcanic rock is classified into andesite, lava, and andesite volcanic breccia, the distribution areas of andesite, lava, and andesite volcanic breccia are classified, the upper and lower limit values of the respective distribution areas are determined, and the respective distribution value regions are determined.

As shown in fig. 9, a density and acoustic time difference (DEN-AC) intersection plate is established, the lithology of the acidic volcanic rock is divided into subclasses, the lithology of the acidic volcanic rock is divided into imperial rock, rhyolite, fractured rhyolite, acidic tuff and fluid volcanic breccia, the distribution areas of the imperial rock, the rhyolite, the fractured rhyolite, the acidic tuff and the fluid volcanic breccia are divided, the upper and lower limit values of the respective distribution areas are determined, and the respective distribution value regions are determined.

As shown in fig. 10, a density-compensated neutron (DEN-CNL) intersection chart is created, the lithology of the secondary volcanic rock is divided into the epigonite, dilongite, keatite and fragmented epigonite, the distribution areas of the epigonite, dilongite, keatite and fragmented epigonite are divided, the upper and lower limit values of the respective distribution areas are determined, and the respective distribution value ranges are determined.

As shown in fig. 1 to 10, comparing the volcanic lithology type of the target area identified by the volcanic lithology identification method of the present invention in fig. 4 to 10 with the volcanic lithology type of the target area to be identified determined according to the basic database in fig. 2 in fig. 3, it can be known that the volcanic lithology identification method of the present invention for identifying volcanic lithology based on the conventional logging information has a high accuracy in identifying volcanic lithology, and further, it can be inferred that the volcanic lithology identification method of the present invention is still applicable to a new exploration area without the above-mentioned volcanic lithology designation database and/or volcanic lithology information database, and the volcanic lithology identification method of the present invention has a high popularization adaptability.

From the above description, it can be seen that the above-described embodiments of the present invention achieve the following technical effects: according to the conventional well logging measurement principle, well logging response characteristics and differences of standard volcanic lava and pyroclastic rock are analyzed and compared, well logging curves sensitive to the lithological response of the volcanic rock are preferably selected to manufacture an intersection chart by means of the lithological scale of a specified area core and a special well logging, the volcanic lava and the pyroclastic rock are firstly distinguished through the intersection chart, then the volcanic clastic rock is subdivided, the volcanic lava is divided into large volcanic lava categories (basal, middle, sour and sub-volcanic rocks) in the third step, and finally a plurality of small categories of the large categories are subdivided step by step according to the large volcanic lava categories (basal, middle, sour and sub-volcanic rocks), and particularly, the volcanic lava containing basal, middle and acidic matrixes is distinguished. The invention is based on the conventional well logging information, can solve the problems that in the well section without coring, without special well logging and with the conventional well logging curve, the method utilizes the thought of classification to establish the volcanic lithology identification chart, quickly identifies the main subclass in the volcanic major classes, eliminates the influence of complicated name determination caused by different matrixes and different internal structural characteristics of the volcanic, the volcanic lithology identification method which can quickly, efficiently and accurately identify the volcanic lithology is provided by taking major identification and acid-base distinguishing as the leading factors and eliminating the interference of reservoir structure factors, meanwhile, volcanic breccids containing base, medium and acidic matrixes can be effectively distinguished, the lithology recognition accuracy of an effective reservoir is improved, the operation is simplified, the cost is reduced, the popularization adaptability is improved, and the world-level problem that the volcanic rock lithology recognition difficulty is high based on conventional well logging is solved. The lithology recognition method has the advantages of high lithology recognition accuracy and simplicity and convenience in operation, is suitable for any logging, drilling site with logging curves and scientific research work, and can be used for assisting in quickly recognizing the lithology, improving the lithology recognition precision of an effective reservoir and increasing the oil-gas exploration and development benefits.

It is to be understood that the above-described embodiments are only a few, but not all, embodiments of the present 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.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular is intended to include the plural unless the context clearly dictates otherwise, and it should be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of features, steps, operations, devices, components, and/or combinations thereof.

It should be noted that the terms "first," "second," and the like in the description and claims of this application and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the application described herein are capable of operation in sequences other than those illustrated or described herein.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A volcanic lithology identification method is characterized by comprising the following steps:

step S20: selecting a plurality of well logs sensitive to volcanic lithology from the standardized database;

step S30: and drawing a logging curve intersection chart capable of identifying different volcanic lithologies based on the plurality of logging curves, dividing the volcanic lithologies and determining the distribution range of the pyroclastic rock and/or the volcanic lava.

2. The volcanic lithology identification method of claim 1, wherein, when the volcanic lithology is the pyroclastic rock, after the step S30, the volcanic lithology identification method further comprises:

step S40: selecting a plurality of well logs sensitive to pyroclastic rock lithology from the standardized database;

3. The volcanic lithology identification method of claim 2, wherein after the step S50, the volcanic lithology identification method further comprises:

step S60: selecting from the standardized database a plurality of well logs sensitive to lithology of the large class of pyroclastic rock;

step S70: and drawing a logging curve intersection chart capable of identifying different lithologies of the large volcaniclastic rocks, and performing subclassification on each lithology of the large volcaniclastic rocks.

4. The volcanic lithology identification method of claim 2, wherein the well log intersection map capable of identifying lithology of different pyroclastic rocks is a natural gamma and density (GR-DEN) intersection map.

5. The volcanic lithology identification method of any one of claims 1 to 4, wherein, when the volcanic lithology is the volcanic lava, after the step S30, the volcanic lithology identification method further comprises:

step S45: selecting a plurality of well logging curves sensitive to the lithology of the volcanic lava from the standardized database;

6. The volcanic lithology identification method of claim 5, wherein after the step S55, the volcanic lithology identification method further comprises:

step S65: selecting a plurality of well logs sensitive to lithology of the volcanic lava major class from the standardized database;

step S75: and drawing a well logging curve intersection chart capable of identifying different lithologies of the major volcanic lava, and performing subclassification on each lithology of the major volcanic lava.

7. The volcanic lithology identification method of claim 5, wherein the well log intersection map capable of identifying different volcanic lava lithologies is an intersection map of natural gamma rays and undisturbed formation resistivity (GR-RT).

8. A volcanic lithology identification method as claimed in any one of claims 1 to 4, further comprising the steps of:

step S05: naming the lithology of the volcanic rock based on data obtained in one or more of outcrop exploration, rock core observation, experimental analysis and slice identification modes to obtain a lithology naming database of the volcanic rock; and/or the presence of a gas in the gas,

step S15: and establishing a lithologic property data database of the volcanic rock based on the lithologic property data of the volcanic rock obtained by the imaging logging and/or element capture logging mode.

9. The volcanic lithology identification method of claim 8, wherein the volcanic lithology identification method further comprises:

step S80: and comparing the lithology name database of the volcanic rock obtained in the step S05 and/or the lithology information database of the volcanic rock established in the step S15 with the lithology of the divided volcanic rock, and judging the accuracy of the volcanic rock lithology identification method for identifying the lithology of the volcanic rock.

10. A volcanic lithology identification method as claimed in any one of claims 1 to 4, wherein the well log intersection map capable of identifying different volcanic lithologies is an intersection map of natural gamma and undisturbed formation resistivity/sonic time difference (GR-RT/AC).