STUDY OF STRATUM WATER AND OIL AND GAS ACCUMULATION RELATIONS OF MAJIATAN AREA IN THE WESTERN ORDOS BASIN

Based on the characteristics of tectonics evolution in the western Ordos Basin,the author compared chemical characters of underground water with paleo-fluid from fluid inclusions,and indicated the relationship between underground water and evolution of oil and gas accumulation.The results from the research suggested that the distribution of formation water at the western Ordos Basin thrust fault-fold belt and its adjacent Tianhuan Depression is from east to west,and the paleo-fluid from fluid inclusions is similar to the ancient stratum water in this area.From the comparison the oil and gas accumulation was in a closed geological environment in the Majiatan area of western Ordos Basin,and with the late influence of tectonic movement,it was damaged,and strongly eluviated with infiltrating surface water.