Abstract:

Based on the classification of faults, using geology statistics and geochemical analysis, the controlling effects of faults on hydrocarbon migration and accumulation in Nanpu Sag are expatiated from macroscopic aspects to microscopic aspects. Faults are divided into three types including the long active fault, the early active fault and the lately active fault. The long active fault, acting as source fault, was important pathway for vertical hydrocarbon migration, and multi oilbearing layers were formed as a result of multiphase activity of the long active fault. The vertical distribution of hydrocarbon was controlled by the phase and intensity of fault activities, and the reservoir was distributed in the traps surrounding source faults. The function of fault for hydrocarbon migration and accumulation was various in different time. The reverse fault-screened trap has better oil-bearing property than the co-dip fault-screened trap, which is favorable target for oil exploration. The reservoir scale of faultscreened trap was controlled by sealing ability of screened fault, so the estimation of fault-sealing has great significance for improving the success rate of drilling.

Key words: hydrocarbon migration and accumulation, source fault, fault-screened trap, fault-sealing, Nanpu Sag