东营凹陷下第三系流体-岩石相互作用研究

盆地内地层流体-岩石相互作用导致储层特征和流体性质发生变化,影响油气藏的形成与分布。本文分析了东营凹陷下第三系地层孔隙流体的化学和动力学特征及其分布规律,根据地层中矿物的组成和结构特征对成岩过程中地层古流体的地球化学特征进行了推测。并通过对典型油田泥岩层和砂岩层中矿物组合及其在地层剖面上的变化规律的实例剖析,揭示了东营凹陷下第三系储层中流体-岩石相互作用的基本特点,在此基础上,建立储层中流体-岩石相互作用的地质/地球化学模型。

Study of Fluid-Rock Interactions in Eogene Formation in Dongying Depression, Bohai Gulf Basin

Fluid-rock interactions in sedimentary basin plays an importantrole in changing characteristics of reservoir rocks and properties of pore fluid, and then affects accumulatiorl and distribution of oil and gas in reservoir. This paper has analyzed formation temperature, pressure condition and the geochemical feature of pore-fluid in Eogene, Dongying Depression, Bohai Gulf Basin. The systems of fluid dynamics have been divided. The fluid dynamics characteristics and its distribution feature in defferent system of fluid dynamics are discussed. Base on the analytical result of composition and structural feature of mineral in mudstone which sampling from 4 section of Shahejie Formation in typical well of Niuzhuang Sag , Dongying Depression. The environment medium condition ( including salinity,pH value and Eh value)in rock diagenetic process and geochemical characteristics of the pore fluid in rock are supposed. According to the combination feature of the major mineral in mud rock stratum and sandstone layer and its distribution law on stratigraphic profile of typical oil field, fluid-rock interaction process would also been divided three stages, which is similar to fluid pressure and chemical characteristics. This paper summarizes the basic characteristics of fluid-rock interaction of different stage in Eogene reservoir, Dongying Depression. The physicochemical factors affecting rock-fluid interaction have been discussed, which include formation temperature, pore-fluid nature and underground fluid dynamics feature and unusual formation pressure tape and so on. Based on the discussion above, a general geological/geochemical model of fluid-rock interaction is established. This research shows the distribution feature, the evolution law of diagenetic mineral, the environment and fashion of fluid-rock interaction are all different in different fluid dynamics system,which is to say that the geological/geochemical model of fluid-rock interaction are different in different fluid dynamics system.