A Study On Chang7Tight Oil Reservoir Seepage Law And Water Injection Feasibility Of Heshui Area

In recent years， the tight oil reservoir is an important reserve composition of high andstable yield in Changqing oilfield, whereas the microscopic pore structure of tight oil reservoirand conventional low permeability reservoir has a significant difference, which brought aserious of problems to the exploration and development work. With the dramaticallyincreasingly the demanding of crude oil, it is very necessary to study the reasonabledevelopment mode of tight oil reservoir.On the basis of the reservoir characteristics research, applying the experiments such asthe single phase fluid flow, oil-water two phase flow, the microcosmic real sandstone model,and nuclear magnetic resonance to study the moveable fluid and the seepage characteristics ofHeshui Zhuang230wellblock in Chang7reservoir, on this basis, combining with theproduction performance data, comprehensive applying the methods of reservoir engineering,analogy, economic evaluation, etc, analyzed the feasibility of using water injection for HeshuiZhuang230wellblock. The research achievements are mainly as followed:(1)When the reservoir permeability is less than0.2×10-3μm2in the study area, there is anobvious start-up pressure gradient, and with the decreasing of the permeability the starting-uppressure gradient is increasing.(2)The seepage resistance in the pore space is large in the study area, the seepagecharacteristics is complicated, When oil-water together permeating, the irreducible watersaturation is high, the two-phase relative permeability is low, the interference between the twophase is strong, the together seepage area is small, the content of the movable fluid is general,the saturation of the movable fluid is not high, the whole reservoir percolation ability is notgood.(3)The Chang7reservoir shows the characteristics of weak oil-wet in the study area onthe whole, the displacement type of water displacing oil is finger-mesh displacement, thewater driving oil and residual oil give priority to the oil film residual oil and the residual oilflow around.(4)Through the analysis of the decline law for the horizontal well of the tight oil inabroad and the Zhuang230wellblock, considering during the early developing period when using the natural energy conforms to the law of hyperbolic decline for the tight reservoirhorizontal well, during the early water injection period conforms to the law of harmonicdecline.The research results of this paper provides the theoretical guidance for making up thenext build well pattern deployment and water injection policy of Heshui Zhuang230wellblock in Chang7reservoir, there is of a great significance for long-term stable yield forZhuang230wellblock, meanwhile, it also provides reference for the similar reservoir.