| The geological evaluation of coal measure strata plays a vital role in the selection of favorable sections of coal measure gas,which is the basis of the subsequent exploration and development projects,and is directly related to the success of coal measure gas exploitation.In this paper,the Yuwang block of Laochang,East Yunnan is taken as the research object.Through the study of the geological characteristics of coal measures strata reservoirs,the coal system gas resources are calculated,and the resource distribution characteristics are analyzed.The optimal index system for favorable sections of coal measures gas is selected.The favorable zones are selected on the plane and the favorable sections are selected vertically to provide scientific basis and important support for the later coal mining gas mining projects.The 3#,7+8#,9#,13#,16# and 19# coal seams in the Yuwang block are mainly coal seams,which are developed in the whole area,and their burial depth and coal thickness vary greatly;The qualitative characteristics are basically the same,mostly semi-bright-semi-dark coal types,of which the coal structure of 16# and 19# coal seams is better,the adsorption and desorption characteristics of each coal reservoir are less different,the main pore types are micropores and transition pores Mainly;the thickness of sandstone reservoirs is small,with feldspar as the main component,and the pore type is mainly micropores and transition pores;the thickness of mudstone is large,with clay as the main component,and the type of organic matter is type ?.Through the horizontal and vertical analysis of coal,sandstone and mudstone reservoirs,the coalseries reservoir symbiosis relationship is established,which can be divided into three types according to the differences between the source reservoirs.Based on the analysis of coalbed gas content in the study area,according to the isothermal adsorption-gas saturation method,a coalbed gas content prediction model was constructed to predict the gas content of each coalbed in the study area;using logging curve superposition,micro-resistance scanning imaging And logging data such as multi-pole array acoustic wave,explained the gas bearing of sandstone in the study area and determined the number of gas-bearing sandstone layers;using logging data and isothermal adsorption experiments to calculate the free gas and adsorbed gas of mudstone,respectively,and then calculate each coal layer Gas content of top and bottom mudstone.The amount of coalbed methane resources occupies an absolute position in the study area,and its resource distribution law represents the resource distribution law of coalbed methane.It is calculated that the areas where the coal system gas resource abundance is greater than 2.0 are mainly concentrated in the middle of the block;the gas saturation of sandstone gas is about 15%,which is mainly distributed near the LCC1 and LC-C4 wells.Large;good mudstone layers are mainly carbonaceous mudstone,thicker near the LC-C2 and LC-C4 wells.For the optimization of favorable coal-bed gas reservoirs,burying depth,resource abundance and structural curvature are selected as coal seam optimization indexes,sand-land ratio as sandstone optimization index,and carbonaceous mudstone thickness as mudstone optimization index.The favorable section of coalbed methane combined production is preferred,with coal body structure,reservoir pressure and interval,critical desorption pressure and near-reservoir ratio,coal bed and roof and floor mechanical properties,gas saturation,permeability ratio as the preferred indicators;for sandstone gas For the problem of co-production with coalbed methane,the ratio of burial depth and permeability is used as the preferred index;for the problem of co-production of mudstone gas and coalbed methane,the depth of burial is used as the preferred indicator;coalbed methane production,sandstone gas and coal seam are selected vertically Favorable section for combined production of gas,mudstone gas and coalbed methane. |
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