The Shale Gas Accumulation And Resource Potential Evaluation Of Yan’an Formation In Central And Southern Ordos Basin

Central and southern Erdos Basin is rich in coal, oil and natural gas, unconventional naturalgas resources. Yan’an Formation coal measure enriched with thick mudstone, oil and coal systemdrilled in Yan’an Formation get shale gas jet. Deposition period of Yan’an formation mainlydeveloped river, Delta and lacustrine depositional system. By identifying key sequence boundary,the Yan’an Formation is divided into3third order sequences, and to restore the palaeogeographicpattern and evolution of the depositional period, then points out the development and occurrenceof mudstone. A large number of experiments based on the test data, this paper analyzes the Yan’anFormation shale organic abundance, organic matter type, and the degree of thermal evolutioncharacteristics, it studys the hydrocarbon generating ability of shale; analysis of shale rockminerals contents, reservoir physical characteristics, gas properties and so on, then study the shalegas reservoir set feature; analysis of caprock development, tectonic action, hydrogeologicalcharacteristics of the study area, study the preservation conditions of shale gas. On this basis, weput forward the key parameter and favorable selected-area and standards to evaluate the resourcepotential of shale gas in continental facies, calculate the thick mudstones shale gas resources ofYan’an Formation within the sequence stratigraphic framework. Use of resource estimation resultand classification method of favorable area, Yan’an Formation mudstones constituency is dividedinto prospects, favorable area and the core area three preferred areas.