Research On Simulation Methods Of Secondary Hydrocarbon Migration In Qikou Sag

Qikou sag locates in Bohai bay basin, north of Huanghua Depression. It is a classicalcontinental rift basin developed on the basement of Mesozoic strata. Qikou sag is one of thelargest and deepest oil-bearing sedimentary sags in Bohai basin. The Qikou sag has a largepotential for exploration and development whose proven oil reserves are only about20percent of the Huanghua Depression. The secondary hydrocarbon migration path anddominant channel has an important influence on the distribution of oil and gas reservoirs inthe recess. Therefore, full understanding of the secondary hydrocarbon migration andaccumulation in Qikou sag is meaningful for looking for oil and gas reservoirs.The simulation of petroleum secondary migration is the most important part of thebasin modeling. The defination of secondary migration is oil and gas migration after gettingin the carriers. In this paper, we calculated and simulated the petroleum secondary migrationby using today’s fluid potential method and three-dimensional two-phase simple method ofhistorical simulation in Qikou sag. Qikou sag is the major hydrocarbon sag in Huanghuadepression because of adequate sources of oil and gas, stable seals and good reservoirconditions. Basing on knowing general geological situation in Qikou sag and combiningwith secondary migration mechanism, we established the geological model. Divide studyarea into grid, record statistics for each grid stratigraphic top and bottom of the depth, thecrude oil gathering strength, porosity data, calculate the fluid potential, petroleumcontaminant in the study area such as Es3, Es2and Es1,and then draw the fluid potentialcontour map and oil distribution plane contour map through recording statistics. We usedthe C#programming language to develop the necessary software by a profound discussionof various calculation methods. Making use of the software to pretreat known data, calculate fluid potential and the amount of petroleum migration in grids, we determinedpetroleum migration paths in the study area. In this paper, we ultimately determined fivefavorable exploration areas,which are Beidagang Buried Hill, Tanggu Xingang buried hill,Banqiao sub-depression, Chengbei fault zone and Nandagang buried hill.