水驱油藏压驱增油效果、作用机制及油藏适应性OA

Well fracturing is an effective measure for remaining oil producing,but conventional guar gum fracturing fluid shows limited effectiveness.In order to clarify the mechanism of"fracture flooding"production enhancement and reservoir adaptive conditions,a preset fracture simulation model is established,and physical simulation experi-ments are conducted on fracture geometry and initiation timing of horizontal and vertical fractures to analyze the in-fluence of 2 different fracture geometries on fracturing oil production increasing effect.Physical simulations of guar gum and polymer ahead-fluid fracturing on vertical fracture-type cores reveal that during oil well fracturing,the fil-tration and retention of polymer ahead fluid along the mainstream direction of injector-producer cause a"resistance increase and permeability decrease"effect,diverting subsequent displacement agents to sweep remaining oil in two-wing areas away from the mainstream direction,thereby achieving better oil production increasing effect.Polymer ahead fluid has superior filtration property,with oil recovery increased by 3.28 percentage points compared to guar gum fracturing fluid.During the fracturing process,high displacement and swept degree of remaining oil in upper and lower matrix of horizontal fracture,i.e.,the producing degree,is conductive to improve the oil production in-creasing effect.The distribution characteristics of remaining oil in water-flooding reservoirs and the filtration and displacement mechanism of fracturing fluids indicate that the reservoir adaptation conditions or basic elements for"pressure flooding"technology include:the fracturing target must be middle and low-permeability layers at the end of producer,fractures must be horizontal,and the ahead fluid must be working fluids with filtration and displace-ment properties.The research results can provide important reference value for oil production increasing effect and reservoir adaptability of polymer fracturing operation in fields.