惠民凹陷沙河街组三段岩性油藏储层孔隙结构特征及油气意义

Pore structure features of lithologic reservoirs in the third member of Shahejie Formation in Huimin sag and their significance in petroleum exploration

按照Edword D.Pittman的方法对惠民凹陷沙河街组三段储层的压汞曲线重新处理,确定了峰点孔喉半径,建立了峰点孔喉半径与孔隙度、渗透率之间的关系,分析其峰点孔喉半径与含油性间的关系,表明惠民凹陷沙河街组三段为常压背景下的岩性圈闭或构造-岩性圈闭,若具备油源供给,圈闭中含油砂层的最小峰点孔喉半径取决于油柱高度。临南洼陷深凹区沙河街组三段为明显超压区,其岩性圈闭中含油砂岩的最小喉道半径取决于圈闭幅度和压力条件。砂岩峰点孔喉半径与其含油性之间的关系实际上反映了不同盆地成藏动力条件。在具备油源供给和圈闭的情况下,峰点孔喉半径是反映不同成藏条件下砂岩中是否聚集油气的重要条件。

By adopting the method proposed by Edword D. Pittman in reprocessing the mercury injection curves obtained from reservoirs in the third member of Shahejie Formation in Huimin sag, the apex versus pore apertures are determined and their relationship with porosities and permeabilities is established. An analysis of the relationship between the apex versus pore aperture and the hydrocarbon enrichment indicates that reservoirs in the third member of Shahejie Formation in Huiming sag are lithologic traps or structural-lithologic traps with normal pressure, and the minimum apex versus pore aperture depends on the height of the oil column in traps provided that effective oil source presents. In the deep Linnan subsag, the third member of Shahejie Formation is obviously over-pressured and its minimum apex versus pore aperture is determined by the trap height and the formation pressure. The relationship between the apex versus pore apertures of sandstone and its hydrocarbon enrichment reflects the hydrocarbon accumulation dynamics in different basins. With the presence of source rocks and traps, the existence of hydrocarbon accumulation in different reservoiring conditions depends heavily on the apex versus pore apertures.