The Flowing Theory Of Oil In Low Permeability Reservoir In Artificial Fracture Network Of Yan Chang Reservoir In JiYuan Oilfield

The oil in low permeability reservoir’s geological reserves is huge,but the physical properties of the reservoir is poor,we often take volume fracturing to low permeability reservoir to increase flowing channel when the fluid flows.Researching the mechanism and process of tight oil is good for improve ultimate recovery.This paper takes YanChang reservoir in JiYuan oilfield as the research object,summarizes its geological characteristics,and divide the reservoir,take Chang7 as research object,its average porosity is 8%,the permeability belows 1mD,the heterogeneity of reservoir is strong.Though microstructure’s type is small pore and tiny throat.When we take the volume fracturing effective into the reservoir,it will become full of pore and fracture,this paper according to the double medium model,thinking about the start-up pressure gradient,deducing equations of motion and seepage,we find: start-up pressure gradient is inversely proportional to permeability’s square root,and is proportional to the limiting shear stress of the fluid.According to the oil and water two phase of water flooding experiment,the irreducible water saturation and the residual oil saturation in this area is very high,the space between oil and water two phase is narrow.According to the nuclear magnetic resonance water flooding experiment,the use of huge pore is high,but the most tight oil is in the small pore,so oil efficiency is depend on the use of small pore.According to the flowing theory of oil in low permeability reservoir,suggesting four points to increase the reservoir oil efficiency: using volume fracturing technology,reducing limiting shear stress of the oil,adopting the shorter well spacing and the higher differential pressure.