Type of Nonstructural Gas Reservoirs in Ordos Basin

The non-structural gas reservoirs in Ordos Basin can be divided into 4 types,such as a reservoir of lithologic trap of sandstone lens,lithologic trap of differential diagenesis,overlying lithologic-formation trap and the reservoir related with weathering and uncomformity surface.The distribution of non-structural gas reservoir is constrained by hydrocarbon generating depression and the distribution of high efficient reservoir,the non-structural gas reservoir is often located in a coincident position of the high efficient reservoir and in the crossover of uplift with depression.The reservoir is located at Yishan slope area between Jinxi fold belt and Tianhuan Depression,it has the characters of less structural deformation,overlying hydrocarbon genetic center in upper and lower Palaeozoic era,growth of high efficient reservoirs and as well as fast lateral changes of reservoir physical properties,it has the condition of forming non-structural traps,which is the major area for gas reservoir exploration in the basin.