关键词: 成藏作用, 成藏模式, 泌阳凹陷, 南襄盆地

Abstract:

Three types of reservoirs,including lithologic,anticlinal and fault block oil/gas reservoirs,are developed in Biyang depression of Nanxiang basin.As to lithologic reservoir characterized by being generated and reservoired indigenously,the upwarping pinch-out sandbodies are nearly perpendicular to the structural contour lines of nose setting,leading to the formation of large area sandstone upwarping pinch-out or lateral margin upwarping pinch-out lithologic oil/gas reservoirs.Such reservoirs more or less experienced three hydrocarbon charging stages,with the middle-late stage as the major one.Oil and gas in the anticlinal reservoir were sourced by both the 2nd and 3rd members of Hetaoyuan Fm and successively migrated downward along the layered sandbodies and accumulated in Xia'ermen anticline.Palaeo-anticlinal + lithologic reservoirs were formed at the end of deposition of Liaozhuang Fm.Faulting at the last stage of deposition of Shangsi Fm modified the previously formed oil/gas reservoirs,leading to the formation of new fault+lithologic oil/gas reservoirs.Complex faulted nose and fault-block traps with various sizes and shapes have been formed in the north slope,due to the NE and NW faultings.Oil and gas in such reservoirs were sourced from the deep depression in the south and migrated laterally from the deep depression to the north before the deposition of Liaozhuang Fm,and migrated upward along faults to the shallow layers after the deposition of Liaozhuang Fm.Such reservoirs are characterized by late reservoiring.It is predicted that the steep slope zone in the southern part of the depression is the favorable area for discovering lithologic reservoirs,the eastern part of the depression is favorable for discovering anticlinal re-servoirs,and the north slope zone is favorable for discovering fault block reservoirs.

Key words: hydrocarbon accumulation, reservoiring pattern, Biyang depression, Nanxiang basin