Development Unit Division And Favorable Area Evaluation For Joint Mining Coalbed Methane In Yuwang Block,Yunnan

Yuwang block develops multiple coal seams in Yunnan Province,which is the important coalbed methane(CBM)exploration right block of Zhonglian CBM Company.Vertical layer groups and plane development unit division for joint mining CBM are very important in exploration and development.Therefore,On the basis of clarifying the basic geological background of CBM in the study area,the physical properties of multi-seam reservoirs in all layers are mainly analyzed,the development unit division method for joint mining and the evaluation process of favorable areas are prososed and perfected.The main results are as follows:Firstly,this paper expounds the basic geological background of the deposition,structure and hydrology of CBM in the late Permian coal-bearing strata,Yuwang block.There developedmulti-layer main coal seams in the study area,the structure is relatively simple and the coal-bearing strata are mainly weak aquifers.Furthermore,using Modflow hydrodynamic field simulation software to predict single well water inflow,it predicts that the main coal seam will not expose liquid level prematurely,which provides theoretical support for the development unit division for joint mining CBM.Secondly,The physical properties of multi-seam reservoirs in Yuwang block are evaluated.The evaluation results show that there are many layers in coal seams,and main coal seams developed 3#,7+8#,9#,13#,16#,19# coal.Coal rank is mainly anthracite,the gas content of coal reservoir varies greatly,and the average gas saturation is 53.98%.Coal reservoir belongs to ultra-low permeability to medium permeability reservoir,but most of them are filled with calcite.The pore is mainly micropore and transition pore.Underpressure to overpressure state of coal reservoirs are all distributed,most of the block belongs to high in-situ stress zones,and the coal structure of coal seams is complex and diverse.The logging interpretation method of coal reservoir has been further improved,and well logging interpretation of physical properties of multi-seam reservoirs in all layers with typical boreholes has been completed.Thirdly,it has been completed that recognition of aquifers in logging interpretation of coal measures strata in Yuwang block.Futhermore,combining sequence division and key layer identification,three sets of fluid systems are divided,the coal-bearing strata are mainly upper and lower sets,including the fluid systems of 9# coal and above,and 9# coal below.The vertical production combination of multiple coal seams is further optimized by using the three-step method of production layer optimization combination,and the main development layers of the study area are determined.Finally,this paper proposed the method of planar development unit division and favorable area evaluation for joint mining CBM.Using mature 3-D modeling method and quantitative classification of key parameters of coal reservoir,completing the optimization of favorable area for single-layer and joint mining CBM in Yuwang block.After verification,the evaluation results are in good agreement with the actual production results.This paper has 169 figures,38 tables and 133 references.