埕北断阶带油气成藏条件与模式研究

Hydrocarbon Accumulation Model of Chengbei Step-fault Zone

黄骅坳陷埕北断阶带具有含油气目的层多,油气藏类型多样,纵向叠置、平面连片,油气复式聚集的特点。油气藏形成的主要控制因素为:充足的油气源、良好储集条件和储盖组合、基岩潜山背景下的断阶构造、长期继承性发育的断层等,其中,断层和盖层是控制油气纵向成藏的关键因素;基岩潜山背景下断阶构造和输导体系是控制油气横向成藏的主导因素。油气富集规律为:平面上,油气沿近东西、北东向主断裂展布;纵向上,油气自北向南、自西向东呈阶梯状分布;储层厚度和物性以及砂体类型控制油气富集程度;圈闭的位置与砂体形态控制油气藏的厚度与含油范围;泥岩盖层控制了油气富集的层位;复式输导体系决定了不整合面上下是油气富集的有利部位;埕北断阶断裂、不整合面及砂岩输导层三者不同的配置关系,构成了研究区多种油气运聚方式,其中"多"字型成藏模式(即阶梯状输导成藏模式)是研究区的主导成藏模式。

Chengbei step-fault zone in Huanghua Depression has diverse oil-bearing target beds and hydrocarbon reservoirs, which are vertically stacked and laterally connected and have multiple hydrocarbon accumulations. The main control factors of the hydrocarbon reservoirs are abundant oil-gas source, fine preservation conditions, fault terraces developed on bedrock buried hills, and longtime successive developing faults, among which, faults and cap rocks are the key factors controlling vertical hydrocarbon reservoirs. Fault terraces developed on bedrock buried hills and passage systems are the leading factors controlling lateral hydrocarbon reservoirs. The regularities of hydrocarbon accumulation are： in plan, hydrocarbons are distributed along the EW and NE major faults. In the vertical direction, hydrocarbons present in a ladder form from north to south, west to east. The thickness and physical properties of the reservoirs and the type of sand body control the extent of hydrocarbon enrichment. The location of traps and the shape of sand bodies control the thickness and oil domain of hydrocarbon reservoirs. Mudstone caprocks control the accumulation horizon of hydrocarbons, multiple transport systems determine that the unconformity surface is the favorable position for hydrocarbon accumulation. The associations of Chengbei fault terrace, unconformity surface and sandstone transport layer form various hydrocarbon migration and accumulation, and the accumulation model of terrace transport is the major model in the study area.