Evaluation And Optimization Of Favorable Blocks And Intervals For Co-exploitation Of Coal Bed Methane And Shale Gas Resources

Coal measure gas is a clean and efficient new unconventional natural gas energy.Considering its reservoir as a whole,comprehensive exploration and development of combined gas reservoirs can greatly reduce the exploitation cost and increase the resource quantity.As an important basic work for exploration and large-scale development in the early stage,the evaluation and optimization effect of favorable sections is closely related to the economic benefits of coal measure gas recovery.In the early stage,preliminary studies have been carried out on the accumulation rules of superimposed coal measure gas in the study area,which indicates that it is suitable for the comprehensive co-exploration and co-exploitation of coal bed gas and shale gas with coal bed gas as the main body in the area.Following the research idea of "from surface to point,from point to line",this Thesis establishes an evaluation and optimization model for favorable sections of CBM and shale gas co-production resource abundance based on uncertain multi-attribute decision making theory and ordered sample optimal segmentation method.Reservoiring geological characteristics,through in-depth analysis of area studies suggest gas source condition,reservoir physical property and storage condition is influence of coalbed methane resource potential of the three key elements,and the potential of hydrocarbon generation,preservation conditions and development condition is shale gas occurrence output of the three main control factors,so as to build a favorable CBM-shale gas mining blocks multi-level evaluation index system.Combining analytic hierarchy process and entropy weight method,the subjective and objective weight of the improvement is determined.According to the actual geological background of the region,the subjection degree of quantitative and qualitative indexes is given by piecewise linear function and qualitative evaluation respectively.Based on the multi-level fuzzy comprehensive evaluation model and GIS grid superposition function,this Thesis realized the evaluation of favorable blocks in the co-production plane of CBM and shale gas.Global Moran's I index was used to measure the spatial distribution correlation of the comprehensive evaluation value in the whole region,and the standard deviation ellipse was created to explore the spatial distribution direction of the evaluation value.Finally,by generating Tyson polygon,the target well location for optimization research of vertical favorable intervals is determined objectively.Based on the three characteristics of reservoir physical property,fluid property and reformability,the discriminant index of interlayer interference of coal reservoir is selected,and the preliminary combination recognition of the coal seam drilled in the research well location is carried out based on the optimal segmentation method of ordered samples.On this basis,the vertical co-production reservoir assemblage of coalbed methane and shale gas is divided according to the characteristics of sequence stratigraphy.In order to optimize the coalesced reservoirs,it is necessary to treat the multi-layer assemblages as equivalent coalesced reservoirs,and put forward the truncated normal distribution interval number to describe the uncertainty characteristics after the coalesced physical properties.Based on this,the Monte Carlo theory and TOPSIS model are introduced to give the optimal sequence of cogeneration,storage and coproduction of CBM and shale gas in the sense of probability characterization.This Thesis contains 19 pictures,10 tables and 135 references.