CN104239666A - Analytic hierarchy process based coal bed methane comprehensive evaluation method - Google Patents

Abstract

The invention provides an analytic hierarchy process based coal bed methane comprehensive evaluation method and belongs to the field of seismic exploration and development of oil gas and coal bed methane. The method includes: (1) acquiring main controlling factors of coal bed methane enrichment by means of areal geology analysis; (2) constructing a judgment matrix according to the main controlling factors; (3) calculating weight values of elements, standing for the main controlling factors of coal bed methane enrichment, in the judgment matrix; (4) setting a coal bed methane enrichment area as a research object layer, setting the main controlling factors as a reference layer, and completing comprehensive evaluation of the coal bed methane enrichment area according to an analytic hierarchy process. The analytic hierarchy process based coal bed methane comprehensive evaluation method has the advantages that by means of a geophysical method and the AHP (analytic hierarchy process), weighting coefficients of the main controlling factors of coal bed methane are obtained by calculation; by means of linear operation and relevant physical geographical predication technological achievements, a coal bed methane comprehensive evaluation map of the coal bed distribution area is obtained, and an evaluation result and an actual drilling result are highly uniform.

Description

A kind of Comprehensive Evaluation of Coal Bed Gas method based on analytical hierarchy process

Technical field

The invention belongs to oil gas and coalbed gas seismic exploration and development field, being specifically related to a kind of Comprehensive Evaluation of Coal Bed Gas method based on analytical hierarchy process, for carrying out the research of coalbed methane reservoir gas distribution prediction.

Background technology

At present, in Process of Sustainable Development, under being in the guide of the megatrend such as energy supply, environmental protection, the exploration and development of coal-seam gas is more and more subject to the attention of common people, and the input for coal-seam gas research is also increasing.But, because the systematic study entirety starting for coal-seam gas is more late, still do not form the method and technology mainly for cbm exploration and exploitation at present, in the urgent need to forming the stronger technique series of the specific aim of effectively carrying out cbm exploration and exploitation.

Coal-seam gas is a kind of Unconventional forage, belongs to the gas that a kind of adsorbability is stronger.Such reservoir is different from conventional oil gas reservoir, has the feature of many uniquenesses, and therefore utilize conventional gas and oil exploration means directly to carry out coal-seam gas prediction and there is certain difficulty, it is larger particularly to carry out coal-seam gas gas distribution prediction difficulty.

Along with the progress of oil gas geophysical techniques, having had multiple method may be used for Comprehensive Evaluation of Reservoirs at present, as conventional Hierarchy Analysis Method, neural network, clustering methodology, Field Using Fuzzy Comprehensive Assessment, AHP evaluation assessment, Grey System Appraisal method etc., the appearance of multiple method has also promoted the process of oil exploration and exploitation, has made larger contribution for oil gas increasing the storage is produced.

Multidisciplinary synthesis assessment technique has larger development and application from technology itself, and conventional evaluation method has two kinds, and one is the evaluation method having dimension index, as total score rating method; But widely used is another nondimensional evaluation method, as weights analysis by synthesis method, index overall approach, efficiency coefficient method etc.Conventional assessment method is applicable to specific aim or reference frame, carries out evaluation contrast effect better for very complicated object.At present Fuzzy Comprehensive Evaluation method is generally adopted to more complicated target, for relating to the integrated evaluating method of fuzzy factors objective system, it considers multifactorial impact, use fuzzy mathematics method to be converted to degree of membership and subordinate function evaluation object and evaluation index, then obtain fuzzy result collection by Fuzzy Compound computing.Gray relative analysis method is also applied in the evaluation of multiparameter, determines optimum reference sequences by sample data, by calculating the degree of association of multisample sequence and this argument sequence, makes comprehensive analysis to evaluation objective.Statistical method is also important evaluation method, conventional has principal component analysis (PCA) and clustering methodology, the former is divided into a few major component multinomial evaluation index, then builds an overall target with the contribution rate of these major components for flexible strategy, passes judgment on according to index; Statistical sample is divided into different classifications by the latter, provides comprehensive evaluation result.Neural network rule is the problem input and output problem of sample being become nonlinear optimization, uses the gradient descent method in optimizing, has very strong function to the identification of problem.Preferred and the integrated evaluating method of index parameter is applied to CBM exploration and development field to some extent, as statistical study and regretional analysis are applied to the Analysis The Main Control Factor in many coalfields, multi-layer fuzzy mathematical evaluation method is applied to the preferred etc. of some coalfield favorable blocks.

The coal-bearing property in coal seam, gas-bearing property and perviousness are the important parameters of CBM exploration and development and resource evaluation, and carry out combination to many kinds of parameters preferred, inquiring into integrated evaluating method and technology, is the important goal of cbm exploration and exploitation.

The analytical hierarchy process (AHP) selected of this research at first by the U.S. plan strategies for scholar Saaty T.L teach last century the seventies formally establish, the method is a kind of level weight method of decision analysis of proposing when studying " each industrial sector carries out distributing electric power to the contribution of national welfare " problem for U.S. Department of Defense at first.Found the stage in theory, there are two kinds of tendencies in the research that relevant decision-making determines: (1) too relies on mathematical model, cannot reflect the sense datum of people; (2) too lay particular stress on behavior, logic, the researching and analysing of reasoning aspect, do not have can be quantitative description factor between correlationship.And the analytical hierarchy process that professor Satty proposes is attempted to find binding site between.This theory is the contact of the first internal factor of analyzing influence problem after fully studying studying a question, and is divided level, single level single goal is carried out to the analysis of mathematics afterwards again.Therefore this is a kind of qualitative, quantitative combination, and complication system is decomposed, and it is multi-level single-objective problem that multiple goal, multiple criteria are difficult to again all quantitative decision problem qualitative.

The method is applicable to the comprehensive evaluation of complex decision, comprising: decision-making, evaluation, prediction etc.Its basic thought: first fuzzy or complicated decision problem is resolved into component; Again these elements are divided into some groups by attribute, form different levels.The element of same level plays dominating role as criterion some element to next level, simultaneously again by the domination of last layer element.What be in the superiors only has an element usually, and it is intended target or the desired result of problem analysis, is called destination layer.Middle level comprises the intermediate link involved by realize target, is called rule layer.Minimum one deck is that the alternative various measure scheme of realize target or the index embodying each criterion factor change are called measure scheme layer or indicator layer.So each factor is formed hierarchical structure by dominance relation, can non-sequence relation effectively between evaluating objects, hierarchy of criteria level, the judgement of Synthetic Measurement decision maker and comparing, the rationality of inspection comparative result, finally determines the weight of each factor.Sum up, the method is on the base carrying out analysing in depth in the essence of decision problem, influence factor and internal relation etc. thereof goes out, utilize less quantitative information to make the thought process mathematicization of decision-making, thus provide easy decision-making technique for the complicated decision-making problems of multiple goal, multiple criteria or non-structure characteristic.Therefore, be applicable to evaluation objective complex structure and be difficult to the situation of accurate quantification.

In sum, coal-seam gas is the unconventionaloil pool that a kind of adsorbability is stronger, and the formation of its reservoir is then by the many factors acting in conjunction being different from conventional gas and oil reservoir.The depth of burial, roof and floor lithologic, Coal Characteristics, reservoir pressure, thickness of coal seam, coal seam reservoirs perviousness etc. in coal seam all cause larger impact to the formation of coalbed methane reservoir and gas-bearing property feature, use single gas distribution prediction method to carry out coalbed methane reservoir gas distribution prediction and evaluation analysis reliability is lower when multiple conditional decision.Although existing multiple comprehensive evaluation analysis method is used in the exploration and development process of conventional gas and oil, in CBM exploration and development field, comprehensive evaluation analysis method is then not mature enough, does not particularly have especially for coal-seam gas gas-bearing property integrated evaluating method.

Summary of the invention

The object of the invention is to solve the difficult problem existed in above-mentioned prior art, a kind of Comprehensive Evaluation of Coal Bed Gas method based on analytical hierarchy process is provided, multi-factor problem is resolved into the relation of domination mutually between different levels, finally obtain the desired result of destination layer.

Compared with prior art, the invention has the beneficial effects as follows:

The present invention is achieved by the following technical solutions:

Based on a Comprehensive Evaluation of Coal Bed Gas method for analytical hierarchy process, comprising:

(1) Dominated Factors of Enriching Coalbed Methane is obtained by areal geology analysis;

(2) according to described Dominated Factors development of judgment matrix;

(3) weighted value of each element representing Enriching Coalbed Methane Dominated Factors in described judgment matrix is calculated;

(4) Enriching Coalbed Methane district is set to goal in research floor, Dominated Factors is set to rule layer, complete the comprehensive evaluation in Enriching Coalbed Methane district according to analytical hierarchy process (AHP).

Dominated Factors in described step (1) comprises: ature of coal, coal seam, oozing property of coal seam reservoirs hole, structure, buried depth and cap rock condition.

Judgment matrix in described step (2) is as follows:

$\left[\begin{array}{cccccc}{a}_{i,j}& a_{i,j+1}& a_{i,j+2}& a_{i,j+3}& a_{i,j+4}& a_{i,j+5}\\ a_{i+1,j}& a_{i+1,j+1}& a_{i+1,j+2}& a_{i+1,j+3}& a_{i+1,j+4}& a_{i+1,j+5}\\ a_{i+2,j}& a_{i+2,j+1}& a_{i+2,j+2}& a_{i+2,j+3}& a_{i+2,j+4}& a_{i+2,j+5}\\ a_{i+3,j}& a_{i+3,j+1}& a_{i+3,j+2}& a_{i+3,j+3}& a_{i+3,j+4}& a_{i+3,j+5}\\ a_{i+4,j}& a_{i+4,j+1}& a_{i+4,j+2}& a_{i+4,j+3}& a_{i+4,j+4}& a_{i+4,j+5}\\ a_{i+5,j}& a_{i+5,j+1}& a_{i+5,j+2}& a_{i+5,j+3}& a_{i+5,j+4}& a_{i+5,j+5}\end{array}\right]$

Wherein, element a in judgment matrix _ijvalue representative be the importance of i-th the relative jth of element element, its numerical value represents with 1 to 9.

Described step (2) comprises further carries out consistency check to judgment matrix, specific as follows:

First following formula is adopted to calculate Mode of Level Simple Sequence coincident indicator:

$\mathrm{CI}=\frac{{\mathrm{\λ}}_{\max }-n}{n-1}$

Wherein, λ _maxfor the eigenvalue of maximum of judgment matrix, n is element number, and CI is that judgment matrix is to conforming departure degree;

Then judge whether CI < 0.1, if so, then the consistance of judgment matrix is rational, otherwise just adjusts judgment matrix.

When dimension is more than or equal to 3, following formula is adopted to obtain coincident indicator:

CR＝CI/RI

Wherein, RI is Aver-age Random Consistency Index value.

Described adjustment judgment matrix is achieved in that the numerical value according to the importance in importance mutual between controlling factor adjustment judgment matrix.

Described step (3) is achieved in that

Product M is done to the value of each row element in judgment matrix _i=a _i1× a _i2× ... × a _ij, M _ithe importance ratio representing i-th element other all elements relative is long-pending;

Ask M _in power root

Utilize following formula to vectorial W _i=(W ₁, W ₂..., W _n) weighted value of each element in each layer judgment matrix is obtained as normalized:

W _i＝W _i/∑W。

Described step (4) is achieved in that

According to the weighted value calculated in step (3), give the geophysics prediction achievement weight coefficient relevant to Dominated Factors respectively, then by the geophysics relevant to Dominated Factors prediction achievement and the product addition of its corresponding weight coefficient being drawn the comprehensive evaluation result in Enriching Coalbed Methane district.

The present invention is effectively analyzing under Enriching Coalbed Methane Dominated Factors prerequisite, setting Enriching Coalbed Methane district according to analytical hierarchy process (AHP) is main target floor, under the rule layer domination be made up of Enriching Coalbed Methane Dominated Factors ature of coal, coal seam, coal seam reservoirs factor of porosity, perviousness, structure, coal seam buried depth, coal seam cap rock etc., realize Integrated Evaluation Technique of Coalbed Methane research.Effectively in conjunction with geophysical method technology and the coal-seam gas Dominated Factors weight coefficient that calculated by analytical hierarchy process (AHP), obtain coal output layer distributive province Comprehensive Evaluation of Coal Bed Gas figure by the comprehensive each relevant earth physics predicts technological achievement of linear operation, evaluation result and actual well drilled result have good consistance.

The present invention is the once innovation of cbm exploration and development field, and the method has the perspective of this art method development, for coalbed methane reservoir gas distribution prediction is offered reference.

Accompanying drawing explanation

Fig. 1 is the foundation of analytical hierarchy process destination layer of the present invention and rule layer.

Fig. 2 is Enriching Coalbed Methane district, test site map of Complex evaluation.

Fig. 3 is the step block diagram of the inventive method.

Embodiment

Below in conjunction with accompanying drawing, the present invention is described in further detail:

The present invention proposes a kind of Comprehensive Evaluation of Coal Bed Gas method based on analytical hierarchy process (AHP) innovatively, the Dominated Factors that considering first affects coalbed methane reservoir carries out coal seam reservoirs gas-bearing property comprehensive evaluation analysis, improve the precision of coalbed methane reservoir gas distribution prediction, there is novelty, for coal-seam gas gas distribution prediction is laid a good foundation, there is property leading in the world.

(1) Analysis The Main Control Factor of Enriching Coalbed Methane

The importantly quality factor affecting Gas In Coalbed Gas Content is the areal structure sport history that occurs of coal-seam gas and the final structural feature that formed and coal seam buried depth situation, and the local such as hydrologic condition and karst collapse col umn special geologic condition also affects the enrichment of coal-seam gas simultaneously.The Dominated Factors of analysis and summary Enriching Coalbed Methane, specific as follows: 1. coal petrography, ature of coal are by the control of sedimentary environment condition; 2. tectonic structure is obvious to Enriching Coalbed Methane control action; 3. the net thickness of overlying strata, coal seam affects Enriching Coalbed Methane; 4. the direct cap rock condition in coal seam controls Gas In Coalbed Gas Content distribution; 5. hydrogeology controls the enrichment of coal-seam gas; 6. coal seam reservoirs physical property characteristic controls Gas In Coalbed Gas Content etc.

(2) application level analytic approach carries out Comprehensive Evaluation of Coal Bed Gas

Enriching Coalbed Methane is primarily of many factors co-controllings such as coal seam distribution, coal characteristics, coal seam reservoirs perviousness, structural attitude, coal seam depth of burial, coal seam cap rock, roof and floor lithologics.According to theoretical analysis, Enriching Coalbed Methane district is set to goal in research floor by the Integrated Evaluation Technique of Coalbed Methane based on analytical hierarchy process (AHP), and the Dominated Factors such as ature of coal, coal seam, coal seam reservoirs factor of porosity, perviousness, structure, coal seam buried depth, coal seam cap rock are set to rule layer, under the control, domination of rule layer, complete the realization of destination layer, namely complete the comprehensive evaluation in Enriching Coalbed Methane district.

Research and analyse subterranean zone geologic aspects, sum up Enriching Coalbed Methane condition, the regularity of distribution, morphogenesis characters etc., the basis that complete layer fractional analysis is set up realizes coal-seam gas gas-bearing property comprehensive evaluation.

(1) Analysis The Main Control Factor of Enriching Coalbed Methane

The importantly quality factor affecting Gas In Coalbed Gas Content is the areal structure sport history that occurs of coal-seam gas and the final structural feature that formed and coal seam buried depth situation, and the local such as hydrologic condition and karst collapse col umn special geologic condition also affects the enrichment of coal-seam gas simultaneously.The Dominated Factors of analysis and summary Enriching Coalbed Methane, specific as follows: 1. coal petrography, ature of coal are by the control of sedimentary environment condition; 2. tectonic structure is obvious to Enriching Coalbed Methane control action; 3. the net thickness of overlying strata, coal seam affects Enriching Coalbed Methane; 4. the direct cap rock condition in coal seam controls Gas In Coalbed Gas Content distribution; 5. hydrogeology controls the enrichment of coal-seam gas; 6. coal seam reservoirs physical property characteristic controls Gas In Coalbed Gas Content etc.

(2) application level analytic approach carries out Comprehensive Evaluation of Coal Bed Gas

Enriching Coalbed Methane is primarily of many factors co-controllings such as coal seam distribution, coal characteristics, coal seam reservoirs perviousness, structural attitude, coal seam depth of burial, coal seam cap rock, roof and floor lithologics.According to theoretical analysis, Enriching Coalbed Methane district is set to goal in research floor by the Integrated Evaluation Technique of Coalbed Methane based on analytical hierarchy process (AHP), and the Dominated Factors such as ature of coal, coal seam, coal seam reservoirs factor of porosity, perviousness, structure, coal seam buried depth, coal seam cap rock are set to rule layer, under the control, domination of rule layer, complete the realization of destination layer, namely complete the comprehensive evaluation in Enriching Coalbed Methane district.

Research and analyse subterranean zone geologic aspects, sum up Enriching Coalbed Methane condition, the regularity of distribution, morphogenesis characters etc., the basis that complete layer fractional analysis is set up realizes coal-seam gas gas-bearing property comprehensive evaluation.

As shown in Figure 3, the specific implementation of the inventive method comprises the following steps:

(1) judgment matrix is made.Judgment matrix is the relative importance in the same level represented in the matrix form between each factor.1st layer is destination layer, is Enriching Coalbed Methane district.(because this destination layer is the unique objects of research, so this layer only has an element not need to build matrix) from the 2nd layer, build the matrix of every one deck from top to bottom, until the bottom (is finally to need the Enriching Coalbed Methane district predicted as destination layer herein in the practical application below, and will 6 Dominated Factors of Enriching Coalbed Methane be controlled as rule layer, be pass criteria layer constrained objective layer.)

Element value in matrix represents the quantitative values of two elements (affecting the Dominated Factors of Enriching Coalbed Methane) relative importance, and its numerical value all represents with 1 ~ 9, and 1 ~ 9 for comparing yardstick, and its concrete meaning is in table 1.The rule layer that hypothetical target layer controls has 5 elements (to determine the number of element during embody rule as the case may be.), the objective result that namely this 5 element influences are final.So the contrast matrix of this rule layer is exactly the matrix of 5 × 5, wherein element a _ijvalue representative be the importance of i-th the relative jth of element element, such as a ₁₃just represent the significance level of factor 1 opposing factors 3.If a ₁₃be 3, so its implication is exactly that to compare element 3 obviously important for element 1; If a ₁₃be 7, so its implication is exactly that to compare element 3 strongly important for element 1.The importance that same factor compares self can show that matrix has two features according to this principle: (1) diagonal of a matrix direction must be 1, because must be equal; (2) a in matrix _ijand a _jinecessarily reciprocal each other.

Table 1

(2) weighted value of each element in each layer matrix is calculated.Each row element in matrix is product M _i=a _i1× a _i2× ... × a _ij, M _ithe importance ratio representing i-th element other all elements relative is long-pending.Afterwards, M is asked _in power root again to vectorial W _i=(W ₁, W ₂..., W _n) make normalized: W _i=W _i/ ∑ W.So just can obtain the weighted value of each element in each layer matrix, can to obtain in whole system between each level further and the relation of inner element.Final comprehensive evaluation analysis can be carried out according to this relation.

(3) consistency check (this inspection was done before step (2)).After setting up judgment matrix, consistency check need be carried out.First Mode of Level Simple Sequence coincident indicator is calculated:

$\mathrm{CI}=\frac{{\mathrm{\&lambda;}}_{\max }-n}{n-1}$

Wherein, λ _maxfor the eigenvalue of maximum of judgment matrix, n is element number, and CI is that judgment matrix is to conforming departure degree.Work as λ _maxnamely=n is completely the same during CI=0; The value of CI is larger, and the crash consistency of judgment matrix is poorer.Generally, as long as CI < 0.1, just think that the consistance of judgment matrix is rational, otherwise just need to re-start to compare between two, adjustment judgment matrix is (specific as follows: in the judgment matrix of structure, each item number certificate represents the significance level that two controlling factors are compared, significance level is that the numeral of application 1 ~ 9 represents, 1 ~ 9 is ratio scale.When CI do not meet be less than the requirement of 0.1 time, the suitable data according to the respective items in importance mutual between controlling factor adjustment judgment matrix, namely change the size of ratio scale, as made significance level into 2 from 1).But when the dimension n of judgment matrix is larger, the consistance of judgment matrix is poorer.Therefore, the requirement to high-order judgment matrix approach should be relaxed, the Aver-age Random Consistency Index RI value of judgment matrix can be introduced, and calculate random index:

CR＝CI/RI

Wherein, the value of RI is as shown in table 2:

Dimension n	1	2	3	4	5	6	7	8	9	10
											RI	0.00	0.00	0.58	0.96	1.12	1.24	1.32	1.41	1.45	1.49

Table 2

(4) in conjunction with actual coalbed methane reservoir, realize result according to analytical hierarchy process (AHP) and carry out Comprehensive Evaluation of Coal Bed Gas analysis.

The effect of the inventive method is described below by an embodiment.

The first step, the geologic aspects of distributed areas, effective analysis coal seam, sum up Enriching Coalbed Methane condition, the regularity of distribution, morphogenesis characters etc., clearly control the Dominated Factors of Enriching Coalbed Methane, as structural attitude, coalbed coring, roof and floor lithologic feature, coal seam reservoirs hole oozing property feature, hydrological characteristics, physical property characteristic etc.;

Second step, determines the dreamboat layer that Enriching Coalbed Methane is predicted and rule layer based on analytical hierarchy process (AHP).In the present invention, Enriching Coalbed Methane district is set to goal in research floor, and the Dominated Factors such as ature of coal, coal seam, coal seam reservoirs factor of porosity, perviousness, structure, coal seam buried depth, coal seam cap rock are set to rule layer, under the control, domination of rule layer, complete the realization of destination layer, namely complete the comprehensive evaluation in Enriching Coalbed Methane district;

3rd step, 6 Dominated Factors of binding hierarchy analytical approach principle and control Enriching Coalbed Methane set up the Integrated Evaluation Technique of Coalbed Methane based on analytical hierarchy process (AHP), by calculating the weight coefficient of 6 Dominated Factors, as shown in table 3.

4th step, the weight coefficient of application Enriching Coalbed Methane Dominated Factors, effectively in conjunction with tectonic analysis relevant to Dominated Factors under geophysical parameters system, discontinuity detecting technique, frequency attribute, zone thickness is predicted, the method and technology such as amplitude attribute and seismic inversion, the map of Complex evaluation in Enriching Coalbed Methane district is obtained by the comprehensive each technological prediction achievement of linear operation, evaluation result shows that the distribution of Enriching Coalbed Methane district is higher with actual well drilled consistance, coal seam reservoirs gas-bearing property shows good well (2 wells, 5 wells, 8 wells) be all in the more favourable region of Comprehensive Evaluation of Coal Bed Gas, gas-bearing property shows bad well (3 wells, 4 wells, 6 wells) be all in coal-seam gas and evaluate poor region.

Specifically be implemented as follows:

Integrated Evaluation Technique of Coalbed Methane research is carried out in Selection experiment target area, in research process, relative enrichment region (need not be judged relative to enrichment region in coal seam, just in order to illustrate that definition Enriching Coalbed Methane district is destination layer) be defined as destination layer, rule layer is then defined as 6 Dominated Factors of Enriching Coalbed Methane, and (6 Dominated Factors are according to the geology characteristic induction and conclusion of coal seam enrichment, it is the main Dominated Factors controlling Enriching Coalbed Methane, this 6 each side must be considered in research coal seam): ature of coal, coal seam, oozing property of coal seam reservoirs hole, structure, buried depth, (such as i=1 represents ature of coal to cap rock condition, i+1 represents coal seam, i+2 represents oozing property of coal seam reservoirs hole, i+3 represents structure, i+4 represents buried depth, i+5 represents cap rock condition, j represents ature of coal, j+1 represents coal seam, j+2 represents oozing property of coal seam reservoirs hole, j+3 representative constructs, j+4 represents buried depth, j+5 represents cap rock condition, so a _ijthen represent the importance of the relative j of i), the foundation of each hierarchy attributes of analytical hierarchy process is as shown in Figure 1.

1. contrast matrix (i.e. described judgment matrix is built?) as follows:

$\left[\begin{array}{cccccc}{a}_{i,j}& a_{i,j+1}& a_{i,j+2}& a_{i,j+3}& a_{i,j+4}& a_{i,j+5}\\ a_{i+1,j}& a_{i+1,j+1}& a_{i+1,j+2}& a_{i+1,j+3}& a_{i+1,j+4}& a_{i+1,j+5}\\ a_{i+2,j}& a_{i+2,j+1}& a_{i+2,j+2}& a_{i+2,j+3}& a_{i+2,j+4}& a_{i+2,j+5}\\ a_{i+3,j}& a_{i+3,j+1}& a_{i+3,j+2}& a_{i+3,j+3}& a_{i+3,j+4}& a_{i+3,j+5}\\ a_{i+4,j}& a_{i+4,j+1}& a_{i+4,j+2}& a_{i+4,j+3}& a_{i+4,j+4}& a_{i+4,j+5}\\ a_{i+5,j}& a_{i+5,j+1}& a_{i+5,j+2}& a_{i+5,j+3}& a_{i+5,j+4}& a_{i+5,j+5}\end{array}\right]---\left(1\right)$

The wherein row at i, j representative element place and row; a _{i, j}∈ [1,9], i=1 ..., 5, j=1 ..., 5, a _{i, j}value represent the significance level of element i relative to element j; Diagonal entry a _{i, j}=1, represent that identity element is equal relative to the importance of self; a _{i, j}=1/a _{j, i}, represent that element i equals the inverse of element j relative to the significance level of element i relative to the significance level of element j.

According to above principle adjustment matrix be:

$\left[\begin{array}{cccccc}1& a_{i,j+1}& a_{i,j+2}& a_{i,j+3}& a_{i,j+4}& a_{i,j+5}\\ {1/a}_{i,j+1}& 1& a_{i+1,j+2}& a_{i+1,j+3}& a_{i+1,j+4}& a_{i+1,j+5}\\ {1/a}_{i,j+2}& {1/a}_{i+1,j+2}& 1& a_{i+2,j+3}& a_{i+2,j+4}& a_{i+2,j+5}\\ {1/a}_{i,j+3}& {1/a}_{i+1,j+3}& {1/a}_{i+2,j+3}& 1& a_{i+3,j+4}& a_{i+3,j+5}\\ {1/a}_{i,j+4}& {1/a}_{i+1,j+4}& {1/a}_{i+2,j+4}& {1/a}_{i+3,j+4}& 1& a_{i+4,j+5}\\ {1/a}_{i,j+5}& {1/a}_{i+1,j+5}& {1/a}_{i+2,j+5}& {1/a}_{i+3,j+5}& {1/a}_{i+4,j+5}& 1\end{array}\right]---\left(2\right)$

2. the calculating of weight

A () value to each row element does product calculation: M _i=a _i1× a _i2× a _i3× ... × a _ij, M _irepresent i-th element relative to the importance ratio of other all elements long-pending;

B () asks M _in th Root

C () is to vectorial W _i=(W ₁, W ₂..., W _n) make normalized: W _i=W _i/ ∑ W, obtains the weighted value of each element of each layer group (i.e. each Dominated Factors).Proportion according to weighted coefficient distribution coal seam Dominated Factors carries out Comprehensive Evaluation of Coal Bed Gas research further.

Be familiar with discrimination matrix (this matrix (3) is the experience understanding summed up according to the understanding in local area and relevant work area, is the example after matrix 2 assignment) is as follows below rule of thumb and to local area:

$\left[\begin{array}{cccccc}1& 3& 4& 6& 7& 8\\ 1/3& 1& 2& 3& 5& 6\\ 1/4& 1/2& 1& 4& 5& 6\\ 1/6& 1/3& 1/4& 1& 3& 5\\ 1/7& 1/5& 1/5& 1/3& 1& 3\\ 1/8& 1/6& 1/6& 1/5& 1/3& 1\end{array}\right]---\left(3\right)$

The amassing of ratio calculating the importance of i-th element other all elements relative is:

$M_i=\left[\begin{array}{c}{M}_1\\ M_2\\ M_3\\ M_4\\ M_5\\ M_6\end{array}\right]=\left[\begin{array}{c}4032\\ 60\\ 15\\ 5/12\\ 1/120\\ 1/3600\end{array}\right]---\left(4\right)$

Ask M _i6 th Roots:

$W_i=\left[\begin{array}{c}2.8\\ 1.7\\ 1.5\\ 1\\ 0.9\\ 0.5\end{array}\right]---\left(5\right)$

(5) formula is normalized and obtains:

$W_i=\left[\begin{array}{c}0.30\\ 0.20\\ 0.17\\ 0.12\\ 0.11\\ 0.1\end{array}\right]---\left(6\right)$

Namely the weighted value of each Dominated Factors in coal seam is obtained, as shown in table 3:

?	Ature of coal	Coal seam	Coal seam reservoirs physical property	Structure	Cap rock	On cover effective layer
							Weighted value	0.3	0.2	0.17	0.12	0.11	0.1

Table 3

3. consistency check:

$\mathrm{CI}=\frac{{\mathrm{\&lambda;}}_{\max }-n}{n-1}---\left(7\right)$

λ _maxfor the eigenvalue of maximum of judgment matrix, i.e. the eigenvalue of maximum of matrix form (3), n is element number.Meet CI < 0.1, then think that the consistance of judgment matrix (3) is rational.

4. the weighted value obtained is applied, effectively in conjunction with method and technology relevant to Dominated Factors under geophysical parameters system, as structure attribute, discontinuity detecting technique technology (ESP), frequency attribute, thickness of coal seam calculates, amplitude attribute, inversion of Density etc., pass through linear algorithm, the geophysical method technological achievement relevant to coal seam Dominated Factors is comprehensively analyzed obtain Enriching Coalbed Methane district comprehensive evaluation result (according to the coal-seam gas Dominated Factors weighted value calculated in table 3, give the geophysics prediction achievement weight coefficient relevant to Dominated Factors respectively, weight coefficient as structure attribute achievement is 0.12, the weight coefficient of thickness of coal seam is 0.2, the weight coefficient of coal seam reservoirs physical property is 0.17 etc., then the comprehensive evaluation result in Enriching Coalbed Methane district is drawn by linear, additive), as shown in Figure 2.

The foundation of destination layer and rule layer in accompanying drawing 1 analytical hierarchy process, be destination layer by relative for coal-seam gas enrichment area definition in research, rule layer is made up of 6 Dominated Factors in coal seam, the comprehensive evaluation of realize target layer Enriching Coalbed Methane feature under the domination of ature of coal, coal seam, oozing property of coal seam reservoirs hole, structure, buried depth and cap rock.

The parameters weighting value calculated based on analytical hierarchy process (AHP) applied by accompanying drawing 2, effectively in conjunction with method and technologies such as tectonic analysis technology relevant to Dominated Factors under geophysical parameters system, discontinuity detecting technique technology, frequency attribute analysis, zone thickness prediction, amplitude attribute and seismic inversions, obtained the map of Complex evaluation in Enriching Coalbed Methane district by the comprehensive each technological prediction achievement of linear operation.Evaluation result shows:

(1) east studying block is compared with two, the relative enrichment of east coal-seam gas, actual well drilled coal-seam gas shows good well (2 wells, 5 wells, 8 wells) (reporting what the coal-seam gas display result obtained was found out according to logging well) and is all on the band of Enriching Coalbed Methane, and coal-seam gas shows bad well (3 wells, 4 wells, 6 wells) and is in the poor region of Enriching Coalbed Methane.

(2) Enriching Coalbed Methane district be not region in flakes, but in band shape, reflect the poor boundary of coal geology accumulating condition and the nonuniformity of coal seam reservoirs transverse direction, also show the importance that coal seam reservoirs is predicted.

Technique scheme is one embodiment of the present invention, for those skilled in the art, on the basis that the invention discloses application process and principle, be easy to make various types of improvement or distortion, and the method be not limited only to described by the above-mentioned embodiment of the present invention, therefore previously described mode is just preferred, and does not have restrictive meaning.

Claims (8)

1. based on a Comprehensive Evaluation of Coal Bed Gas method for analytical hierarchy process, it is characterized in that: described method comprises:

(1) Dominated Factors of Enriching Coalbed Methane is obtained by areal geology analysis;

(2) according to described Dominated Factors development of judgment matrix;

(3) weighted value of each element representing Enriching Coalbed Methane Dominated Factors in described judgment matrix is calculated;

(4) Enriching Coalbed Methane district is set to goal in research floor, Dominated Factors is set to rule layer, complete the comprehensive evaluation in Enriching Coalbed Methane district according to analytical hierarchy process.

2. the Comprehensive Evaluation of Coal Bed Gas method based on analytical hierarchy process according to claim 1, is characterized in that: the Dominated Factors in described step (1) comprises: ature of coal, coal seam, oozing property of coal seam reservoirs hole, structure, buried depth and cap rock condition.

3. the Comprehensive Evaluation of Coal Bed Gas method based on analytical hierarchy process according to claim 2, is characterized in that: the judgment matrix in described step (2) is as follows:

$\left[\begin{array}{cccccc}{a}_{i,j}& a_{i,j+1}& a_{i,j+2}& a_{i,j+3}& a_{i,j=4}& a_{i,j+5}\\ a_{i+1,j}& a_{i+1,j+1}& a_{i+1,j+2}& a_{i+1,j+3}& a_{i+1,j+4}& a_{i+1,j+5}\\ a_{i+2,j}& a_{i+2,j+1}& a_{i+2,j+2}& a_{i+2,j+3}& a_{i+2,j+4}& a_{i+2,j+5}\\ a_{i+3,j}& a_{i+3,j+1}& a_{i+3,j+2}& a_{i+3,j+3}& a_{i+3,j+4}& a_{i+3,j+5}\\ a_{i+4,j}& a_{i+4,j+1}& a_{i+4,j+2}& a_{i+4,j+3}& a_{i+4,j+4}& a_{i+4,j+5}\\ a_{i+5,j}& a_{i+5,j+1}& a_{i+5,j+2}& a_{i+5,j+3}& a_{i+5,j+4}& a_{i+5,j+5}\end{array}\right]$

Wherein, element a in judgment matrix _ijvalue representative be the importance of i-th the relative jth of element element, its numerical value represents with 1 to 9.

4. the Comprehensive Evaluation of Coal Bed Gas method based on analytical hierarchy process according to claim 3, is characterized in that: described step (2) comprises further carries out consistency check to judgment matrix, specific as follows:

First following formula is adopted to calculate Mode of Level Simple Sequence coincident indicator:

$\mathrm{CI}=\frac{{\mathrm{\&lambda;}}_{\max }-n}{n-1}$

Wherein, λ _maxfor the eigenvalue of maximum of judgment matrix, n is element number, and CI is that judgment matrix is to conforming departure degree;

Then judge whether CI < 0.1, if so, then the consistance of judgment matrix is rational, otherwise just adjusts judgment matrix.

5. the Comprehensive Evaluation of Coal Bed Gas method based on analytical hierarchy process according to claim 4, is characterized in that: when dimension is more than or equal to 3, adopts following formula to obtain coincident indicator:

CR＝CI/RI

Wherein, RI is Aver-age Random Consistency Index value.

6. the Comprehensive Evaluation of Coal Bed Gas method based on analytical hierarchy process according to claim 4 or 5, is characterized in that: described adjustment judgment matrix is achieved in that the numerical value according to the importance in importance mutual between controlling factor adjustment judgment matrix.

7. the Comprehensive Evaluation of Coal Bed Gas method based on analytical hierarchy process according to claim 6, is characterized in that: described step (3) is achieved in that

Product M is done to the value of each row element in judgment matrix _i=a _i1× a _i2× ... × a _ij, M _ithe importance ratio representing i-th element other all elements relative is long-pending;

Ask M _in power root

Utilize following formula to vectorial W _i=(W ₁, W ₂..., W _n) weighted value of each element in each layer judgment matrix is obtained as normalized:

W _i＝W _i/∑W。

8. the Comprehensive Evaluation of Coal Bed Gas method based on analytical hierarchy process according to claim 7, is characterized in that: described step (4) is achieved in that

According to the weighted value calculated in step (3), give the geophysics prediction achievement weight coefficient relevant to Dominated Factors respectively, then by the geophysics relevant to Dominated Factors prediction achievement and the product addition of its corresponding weight coefficient being drawn the comprehensive evaluation result in Enriching Coalbed Methane district.