Study On The Seepage Law Of Injector-Producer Group In Fractured Low-Permeability Reservoir

The low-permeability reservoir is holding a growing proportion in the proved oil in place of China. For its low permeability, complex geological condition and starting pressure gradient, the low permeability reservoir has low productivity and is difficult to recover. The hydraulic fracturing technique can increase the permeability around the wellbore, decrease the flow resistance, and raise seepage velocity. In general case, hydraulic fracturing technique is able to increase benefit. But the flow in hydraulic fracture is non-Darcy flow with high flowing velocity in certain condition, which makes the whole process more complex.Based on the research on the literatures about fracturing development and simulation of low-permeability reservoirs home and abroad, this paper gives a mathematic model which can take both low velocity non-Darcy flow and high velocity non-Darcy flow into consideration. And it gets the results by difference method. A programme is compiled by C# language about that. This paper studies effects of such parameters like starting pressure gradient, formation permeability, flow conductivity, attenuation coefficient of the fracture, width, azimuth, the half length of the fracture, the producing pressure drop, different fractured wells and so on.Studies have shown that: The formation is the main media for oil and water flowing. The lower the formation permeability is unfavorable to the flow. For this reason, it has lower production. The starting pressure gradient has significant influence on the development of low permeability reservoir. It should not be ignored during production. The bigger the starting pressure gradient is, the harder the flowing is. Artificial fractures can improve the flowing environment of the reservoir. By raising the daily oil production and water injection rate, fracturing is important to increase the benefit of low-permeability reservoir. The fracture conductivity is an important index to judge the success or failure of fracturing. By comparing different parameters, it's sure that the higher conductivity, the bigger production at early stage is. However, the non-Darcy flow tends to happen at higher fracture conductivity. The fracture effect falls with an increase in attenuation coefficient of conductivity. The longer fracture length will contribute to the oil production and water injection rate, but the proportion increased is less and less. The fracture azimuth will change the flood response time, and then change the ultimate recovery. The simulation results support that when the fracture is parallel to well array, it will has the biggest cumulative oil production. Lower flowing pressure within some specific limits in producing well causes bigger pressure differential and higher production. Effects have yielded after fracturing either on producing well or on injecting well. But obviously first scheme is more efficient.