摘要
本文从动水条件下流体势分布特征的分析出发,根据视水头梯度的概念,讨论了构造产状对等油势面倾角的影响,提出了动水条件下单斜储层中油气运移方向的判别公式,并得出了构造和地层圈闭在动水条件下毛细管压差可以封存的最大油柱高度的计算公式。作者认为,水动力必须和构造或岩性配合才能封闭油藏,纯粹的水动力圈闭不可能存在。在此基础上,作者从势分布的角度给出了圈闭的定义,这个定义不仅适用于静水环境,也适用于动水环境。
Abstract
Through the analysis of fluid potential distribution Under hydrodynamic conditions. this paper discusses the conditions for petroleum migration and entrapment. The angle of inclination of oil-water interface (α) is a function of the dipangle () of the aquifer. which confines the water flow direction: tga=∂h/∂x/ρ-ρ/ρ-ρh/∂x·tgθ (1)where ∂h/∂x is the horizontal component of water head gradient within theaquifer, and θ is the dip angle of the aquifer. In an anticlinal aquifer, the maximun height of the oil column perpendicular to the oil water interface is given by: Z=(2σ[(1/γ-1/γ)]g·(ρ-ρ))·√ (2) where tgα can be obtained by solving equation (1), assuming that α=θ.In an updip pinchout reservoir, the maximum height of oil column may be: Z=(2σ|(1/γ-1/γ|)/(g·(ρ-ρ)-(∂h/∂x)·(ρ·g/cosθ·sinθ)) (3) A F function is derived to determine the direction of oil and gas migrationin a monoclinal aquifer with a downdip flow:F=∂h/∂x-ρ-ρ/ρ·sinθ·cosθ (4)A hydrocarbon globule will migrate updip when F is negative. It will be flushed down the dip if F is positive. It is concluded that without the closure of structure and lithological variation, hydrodynamic factor alone can not trap hydrocarbons.
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