Analysis of the genesis of the water-rich oil reservoir in the Lijiacha prospect area in the east of the northern Shaanxi slope

Abstract：On the basis of the statistic analysis of the oil tests and data of production of 110 wells in the study area, the paper summarizes the areal and vertical variations of oil content in the Lijiacha prospect area in the east of the northern Shaanxi slope and discusses the cause of the high water content. The water content in the study area is high in the north, low in the south, low in the center and high in the east and west and vertically has the trend of becoming low from the base upward. According to the source rock and physical conditions and a comparative study of these conditions with neighboring areas, the authors think that: the lack of hydrocarbon is the most important cause for the high water content in the oil reservoir of the Lijiacha prospect area, the poor migration conditions are an important cause and the low-porosity and -permeability reservoir conditions are also one of the causes for the high water content.