Coal Accumulation And Target Optimization For Exploration Of CBM In Permo-Carboniferous, Ordos Basin

Thesis utilization cores, well logs, logging, coal drilling and outcrop , etc., combined with previous research results,In-depth research of the Ordos Basin Late Carboniferous Benxi - Early Permian Shanxi Shan 2 sub-period of the deposition system and its temporal evolution,careful analysis the coal environment and the regularity of coal-accumulation of the main coal seam that is Benxi No. 8 and No. 5 seam in the Shanxi Formation, and through geological conditions of coal bed methane gathering analysis and research, pointed out that the favorable area for coalbed gas exploration.From the outcrop observation, core description, single well facies analysis and even the well section facies contrast, combining with the formation thickness, thickness of sandstone, sandstone thickness and stratigraphic thickness ratio and limestone thickness of a single factor maps, analysis of the Ordos Basin Late Carboniferous Benxi, Early Permian Taiyuan and the Early Permian Shan 2 sub-period sedimentary facies.Discussion of the different sedimentary facies of fabric characteristics and evolution.That from the Late Carboniferous Benxi to the Early Permian Shanxi period, Ordos Basin has experienced inland from the epicontinental basin to the process of evolution , Main sedimentary facies are identified tidal flat, lagoon, barrier island, muddy shelf, carbonate platform,the northern part of the basin can be identified such as delta plain and delta front depositional facies. The mainly facies are alluvial fan, fluvial, delta and lacustrine facies in Early Permian Shanxi Shan 2 sub-period.On the basis of a large number of statistical data, analysis of the main coal seam thickness, depth, roof and floor lithology.Combined with the thickness figure and the facies of a detailed study of the coal aggregation environment and the regularity of coal-accumulation.That the Ordos Basin, Carboniferous - Permian No.8 seam and No.5 seam mainly formed in the environment peat swamps and peat flat, and continue to divide and diffuse the peat swamps of the river, delta plain peat swamp, lagoon peat flat, peat flat after the barrier island, tidal flat peat flat, shallow-water delta peat flat, platform peat flat and muddy shelf floor, total of eight coal aggregation environment.Discussed the distribution characteristics of the area that the coal’s deposition, aggregation and enrichment, summarizes main seam plane distribution morphology and combinations morphology, described the main factors of coal aggregation environment.Choose two areas for coalbed methane exploration: Southeast margin of the Ordos Basin, Daning-Hancheng favorable area and the Northwest margin of the Ordos Basin, Wuhai–Zhuozi Mountain favorable areas.Wuhai-Zhuozi Mountain area has a large coal seam thickness, depth moderate, CBM preservation conditions are good, moderate coal rank, gas content higher favorable characteristics, but the exploration area is small, the high ash content in coal bed methane exploration of its adverse factor.In Daning-Hancheng area,the coal seam thickness has a large, flat distribution of more stable, moderate depth features, main seam of coal with a high vitrinite content, in the low ash and medium-high rank of the feature, its seam adsorbed gas content should be high, is ideal for CBM exploration target area.