Abstract:

On the basis of reservoir cores research and log interpretation, the research established criteria for reservoir classification of the Lower Urho of Region Eight both statically and dynamically. Using comprehensive evaluation method, reservoirs in the entire region were divided into four categories. The best was class I, the worst was class IV. Good results have been achieved when this method was used in the four encryption tests. Prediction error of reservoir thickness was within 5%, and matching rate of reservoir types was 80%. According to the regional tectonic evolution and various characteristics of the stress field, geological background of crack formation in Lower Urho of Region Eight was analyzed. With the statistical data of cores and logging imaging, natural fractures of the Lower Urho of Region Eight are dominated by highangle joints. Artificial joints are dominated by fracturing pinnate joints and all kinds of cracks are mostly close cracks. Combined with the dynamic data of development, our study concludes that reservoir welldeveloped area controlled the distribution area of oil fields with high production. The better the oil reservoir conditions, the higher the initial production. The existence of cracks results in the prior onrush of the injected water along the crack causing fracture water breakthrough and the presence of water but no effect. Comprehensive analysis concludes that different oilwater displacement channels (reservoir matrix and fracture) and different development of reservoir and cracks lead to different effects on oil wells. On the basis of the mentioned static and dynamic study, the oilfield implemented four encryption test wells and more than 90% wells achieved the designed capacity.

Key words:  Lower Urho of Region Eight, reservoir, fracture, development effect, the fourth infill