FORMATION CONDITIONS AND DISTRIBUTION CHARACTE-RISTICS OF LITHOLOGICAL RESERVOIRS IN THE QIANJIANG SUBBASIN

The unidirectional,multi-source,saline-lake sedimentary system and structural background of the Qianjiang subbasin are the necessary geological conditions for the formation of a number of genetic types of lithologic reservoir in the Qianjiang saline lake.The lithologic reservoirs may be divided into 15 subtypes of 4 types.The organic combination of sandstone pinchout line and structure is the major factor responsible for the formation of the lithologic reservoirs.Vertically,lithologic reservoirs mostly occur in the Third and Fourth members of the Qianjiang Formation,and in plan view,they are mainly developed on the structural slopes facing the material source and in areas where the combinations of faults and sandstone edge pinchout are concentrated.