3D Geological Modeling Of Yuwang CBM Block And Productivity Prediction Of Overlying Gas-bearing System

Based on the comprehensive application of geological modeling theory,coalbed methane numerical simulation theory and coalbed methane(CBM)reservoir modeling technology,this paper selected the Yuwang block in the Laochang pilot CBM)exploration and development area to carry out digital geological modeling and multi-layer coal seam gas well productivity research.First,the outlier target coal reservoirs(9~#coal seam,13~#coal seam,19~#coal seam)and modeling principles based on basic geological information are formulated.Subsequently,based on the modeling principle of highlighting the target coal reservoir(No.9,13 and 19 of coal seams)and finely describing the key areas,the modeling technology used in the modeling work was determined.It mainly includes fault modeling and grid subdivision technology,interpolation technology,model coarsening technology,attribute model constraint technology and attribute modeling technology.For the study area,this paper determined the procedure of modeling as the follows:basic data collection,data importing,layer generation,fault model establishment,plane grid subdivision,layer model establishment,layer volume model establishment,sequence stratigraphic model establishment,vertical grid subdivision,physical property data coarsening and attribute constraint modeling.The geological modeling software Petrel 2009 was used to conduct stratigraphic modeling,fault modeling,grid subdivision,attribute modeling,lithofacies data coarsening,and physical property data coarsening.And finally the basic geological model,spatial model and attribute model of the Yuwang block were established.The model information of No.16,18 and 19 coal seams was extracted from the above model,and the typical drainage well LC-C2 was selected to conduct reservoir simulation by using the COMET3 software.The results show that the total gas production of LC-C2 well in 1500 days is 10,1284.6 m~3,and the average daily gas production rate is 67.5 m~3/d.The gas production of 18 coal seam is dominant in both two-layer drainage and three-layer drainage stages,which is the main production layer of the well.The gas production gradually decreases with the increase of the Langmuir volumn,while it gradually increases with the increase of gas content,permeability,Langmuir pressure and reservoir pressure.Grey correlation analysis was used to analyze the influence of various parameters on productivity.The Results showed that fracturing permeability has the most obvious influence on the productivity of combined production wells,and the Langmuir volumn had the weakest influence on the productivity of combined production wells.150 m is the best scheme for the spacing of CBM wells in this block,and the diamond well pattern plus central well is the best scheme for the layout of CBM development well pattern.The paper contains 33320 words,54 figures and 37 tables.