Experimental Study On Heavy Oil Thermal Recovery Mechanism And Displacement Efficiency

Heavy oil is an important part of oil resources.Since the first application of steam injection technology at the end of the 50's last century,the heavy oil production of the world has been increasing rapidly,currently taking an important position in the entire crude oil production.With the increasing demand of global economy on oil and the development of oil production technologies,a lot of research has been studied on the thermal recovery of heavy oil reservoirs.Therefore,the efficient development of heavy oil has direct practical significance and far-reaching strategic influence on maximizing the use of precious oil resources and meeting the requirement of the construction of the national economy.The development of heavy oil mainly rely on thermal recovery,reservoir rock and fluid properties will change with the injection of hot fluids,eventually leading to the change of oil-water /stream-water flow law.This paper,based on widespread investigation and study,determines Crude Oil viscosity-temperature relationship,thermal expansion and thermal properties of the rock sample,then analyzes the mechanism of viscosity reduction and thermal expansion in the process of heavy oil thermal recovery,etc.A series of experiments are designed to investigate the influence of heavy oil thermal recovery effects on two phase flow,including the effect of temperature&heavy crude oil viscosity on high-temperature heavy oil-water relative permeability curves,and the change rule of oil-stream relative permeability curves at different temperatures,discovers that heavy oil-water relative permeability curve is largely different from Conventional crude oil-water phase permeability curv.In order to optimize the JBN method in calculation of heavy oil-water/stream relative permeability curve,the quasi-uniform cubic B-spline is applied to fitting the experimental data,the study finds that Logarithmic relationship can well said oil phase relative permeability?Kro?and water saturation?S_w?,and Quadratic polynomial can well said the relationship of-log?Krw?and S_w(S_w?S_wc).The oil-water relative permeability curve formula with temperature changes is established,which is based on the relationship of oil-water relative permeability and water saturation,irreducible water saturation S_wc,residual oil saturation Sor.Finally,on the basis of heavy oil-water/stream relative permeability curve,A series of long-core displacement experiments are designed to study the displacement efficiency of heavy oil thermal recovery of each development way and the influence of temperature on the hot-water flooding and steam flooding;the study finds that the displacement efficiency of steam flooding is best,with the increase of the temperature,the displacement efficiency is increased.