东营凹陷第三系流体物理化学场及其演化特征

Fluid Physicochemical Field and Its Evolution in Tertiary System, Dongying Sag

东营凹陷第三系为最重要的油气层系,具有下列流体物理化学场及其演化特征:①地温梯度较高(现今地温梯度为3.6℃/100m),自凹陷形成以来,地温梯度和大地热流值变化不大;②地层流体压力为中等超压—强超压,在剖面上可划分为静水压力带、过渡压力带和地质压力带;③地层水主要表现为沉积埋藏水的特点,并经历了沉积作用、埋藏与淋滤作用并存和埋藏封闭作用3个演化阶段;④存在着静水压力、过渡压力和地质压力3个流体动力系统,其中过渡压力流体动力系统中流体物理化学作用最为活跃;⑤流体动力经历了始新世、渐新世和上新世—第四纪3个演化阶段,各个阶段表现出不同的流体动力特征。

The Tertiary system is an important hydrocarbon-bearing series of strata in the Dongying sag. The features of its fluid physicochemical field and evolution are as follows: (1)the geother-mal gradient is relatively high (3. 6℃/100 m now). The geothermal gradient and geotherma flux have changed slightly since the sag was formed. (2)The formation fluid pressure is medium - high overpressure. The profile can be divided into static pressure zone, transitional pressure zone and geopressure zone. (3) The formation water has the feature of the burial depositiona water and underwent deposition, burial and leaching as well as burial-closing. (4)There are three fluid dynamic systems of static pressure, transitional pressure and geopressure. The fluid physicochemical action is the strongest in the fluid dynamic system of the transitional pressure. (5)The fluid dynamics underwent three evolution stages, i. e. Eocene, Oligocene and Pliocene Epoch -Quaternary Period, and there are different fluid dynamic features in different evolution stages.