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 (θ) of the aquifer. which confines the water flow direction: tga=∂h_ω/∂x/ρ_ω-ρ₀/ρ_ω-ρh_∂/∂x·tgθ (1)where ∂h_ω/∂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: Z₀=(2σ[(1/γ_t-1/γ_p)]g·(ρ_ω-ρ₀))·√1+tg²α (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: Z₀=(2σ|(1/γ_t-1/γ_p|)/(g·(ρ_ω-ρ₀)-(∂h_ω/∂x)·(ρ_ω·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_ω/∂x-ρ_ω-ρ₀/ρ_ω·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.