Three-dimensional Geological Modeling And Dynamic Characteristic Analysis Of Coal Reservoir In Baode Unit ?

The Baode block in the eastern margin of the Ordos Basin has now achieved commercial exploitation,and significant progress has been made in reservoir characterization and productivity evaluation.However,it is limited to individual wells and observation points,and fails to show the gas reservoir elements on the plane and vertically.Change characteristics.In this paper,Baode unit?is used as the research object,which comprehensively utilizes well logging,drilling and logging,experimental data and productivity data,and adopts random modeling algorithms to finely characterize the distribution laws of coal reservoir physical property parameters in three-dimensional space.Analysis of the main control factors for realizing the productivity of CBM wells horizontally and vertically;assessing the current status of CBM reservoir exploitation in the study area,evaluating the extent of resource extraction,and pointing out the dominant areas of CBM resources.(1)The log interpretation model of coal reservoir permeability was optimized and established.A gas log interpretation template combining gray correlation and support vector machine was established to explain the physical characteristics of coal reservoirs.Based on this,a three-dimensional geological model of coalbed gas reservoirs was established to realize three-dimensional visualization of the physical properties of coal reservoirs.The coal reservoir in the study area is a monoclinic stratum that tilts westward.The stratum is gentle with small folds.In the plane,the permeability of coal and rock decreases from east to west;but the heterogeneity in the permeability layer is strong.On the plane,the gas content of coal rocks gradually increases from east to west,while the heterogeneity within the layer gradually decreases.On the whole,the physical properties of the 8+9#coal seam in the study area are better than the 4+5#coal seam.(2)Based on the geological model,the productivity response characteristics of two typical wells were analyzed,and the factors affecting productivity were clarified.The plane distribution rules of equivalent gas content,resource abundance,adsorption saturation and equivalent permeability of coal reservoirs in the study area were analyzed,and the geological conditions of wells B1-X1 and B1-X2 were compared and analyzed.The parameters are better than B1-X2wells.It can be seen from the cross-hole profile and production curve that the difference in productivity between the two wells mainly includes two aspects:on the one hand,resource conditions,the gas content and resource abundance of the coal seam in wells B1-X1 are better than those in wells B1-X2,and wells B1-X2 The low saturation of coalbed methane adsorption makes gas desorption more difficult;on the other hand,the physical properties of the reservoir,the permeability of the coal seam in wells B1-X1 is better than that in wells B1-X2,and the capping of the roof and floor of wells B1-X2 is weak.As a result,the roof water channeled and the gas production was lower and the water production was higher,so that the productivity of well B1-X1 was better than that of well B1-X2.(3)Combined with the CBM well drainage and production data,the single well productivity data was converted into a reduced coalbed gas content within a certain discharge radius,and then the degree of exploitation of the CBM reservoir in the study area was calculated,and the characteristics of the CBM resource were evaluated.The development status of the study area is relatively good,with continuous high production.By the end of 2017,the gas content produced in the coal seam was 0~4.18 m~3/t,with an average of 0.77 m~3/t.The low-valued gas production areas are mainly located in the western,southwestern,and northeastern regions.The produced gas content is generally less than 0.5m~3/t,and the recovery rate is less than 10%.The remaining resource potential is huge.The high-valued gas production areas are mainly It is located in the west-central-northern region of the study area.The maximum gas production can reach 4.18 m~3/t,and the recovery rate is generally lower than 40%,mainly lower than 20%.Overall,the recoverable reserves in the study area are still huge.