Experimental Studies On The Flow Mechanisms In Fractured Heavy Oil Reservoirs

In the process of developing fractured carbonate heavy oil reservoir, often accompaniedby changes of reservoir porosity, permeability, and crack open degree. They will reduceproduction of fractured reservoirs in such a way to reduce the harvest of crude oil rate.Structuring fractured core test system of the stress sensitivity by ourselves, this paper studiesthe law and mechanism of changes of stress sensitive in fractured reservoirs, which provides atheoretical basis and experimental guidance for the rational exploitation of fracturedreservoirs. Starting from the actual development process of the fractured reservoir, thisessay studies the stress sensitivity variation of different mining period, different types anddifferent matrix permeability. Experimental studies have shown that the strength of stresssensitivity of the different periods of fractured reservoirs is differrent. The minimum stresssensitivity of early development increases as time gose by. And draw a fractured corepermeability curve with the variation of the effective stress. Through equation regression fit,we found that there are different regularity between different cracks fracture permeability andeffective stress. The effective stress and permeability of fractured core which can be closedhave exponent relationship. The others without a closed crack has stage exponent (segmented)relationship. The study found that the matrix stress sensitivity is very weak in fracturedreservoir, the presence of cracks increase its sensitivity, but the changes in the process ofloading and unloading of different matrix permeability core is close to each other.This article through test device of relative permeability curve, test crack oil-water, oiland gas relative permeability curves, cracks in the matrix, the viscosity of crude oil, as well asthe influence on relative permeability by effective stress. Study found that compared with thematrix relative permeability curves, the two-phase region of the crack phase permeabilitycurves is smaller, the water permeability changes rapidly and irreducible water saturation istoo large. With the increasing of viscosity, irreducible water saturation increases, elevatedisotonic point location increases. With the increasing of the effective pressure, isotonic pointof oil and water, oil and gas relative permeability curves and ultimately flooding efficiencydecrease, irreducible water saturation increases, residual oil saturation is essentially the same.