A Study On Reservoir Evaluation And Oil-water Distribution At Water Cut Stage

Classification of the reservoir flow units with the multi-parameter, quantitative and qualitative method has become a trend of the reservoir description. Taking reservoir of Sanjianfang formation of the Qiuling oilfield in Turpan-Hami Basin an example, choosing six parameters, such as porosity, permeability, oil saturation, saturation in the value of pressure, back efficiency and clay content of mercury, and utilizing GAHP to divide the reservoir flow units of the stuy area on the base of sedimentary units, sedimentary microfacies and reservoir heterogeneity.At first, this paper has analyzed the reservoir geological characteristics of Sanjianfang Formation of the Qiuling oilfield, with application of AHP, the reservoir of Sanjianfang Formation has been divided into five reservoir sands group which included 23 small layers (single sand body), based on combining previous studies with dynamic data of the production and development in Qiuling oilfield closely. Then sedimentary characteristics, properties, and heterogeneity of the reservoir have been analysised.According to the characteristics of flow unit, using GAHP to divide the reservoir flow units based on selecting a reasonable parameters, and multi-disciplinary, multi-method. And E, G, M, P 4-type mobile units have been compositly analysised. Finally, influences on waterflooding effectiveness of different flow units have been analysised to verify results of flow units division dynamicly.Analysis have showed, E-type mobile units have mainly distributed in the center of underwater distributary channel, which developed intergranular pores, dissolution porosity, and micro-cracks partly. Also, it has the best best reservoir properties, weak heterogeneity and the strongest flow capacity which has good connectivity, and the main contact is the point of contact. In the water injectiig period, E-type mobile units was not the development of post-injection flow units of the main oil-producing which initial liquid production was higher, water injection was quick early, water cut rise fastly, and was easy to flooding. G-type mobile units have mainly distributed in underwater distributary channel, which developed intergranular pores, dissolution porosity. It has the better reservoir properties, weak heterogeneity and the stronger flow capacity which has good connectivity, and the main contact is from point to line contact. During water injectiig, G-type units were main oil flow units,which waterline promoted more uniform,recovery were relatively higher, and the initial amounts of liquid were medium, but the water rose slowly. If injection rate and injection pressureof G-type units were better controled, they will get better development results. M-type units have mainly distributed in the edge of underwater distributary channel, which hadn,t developed intergranular pores, dissolution porosity. It has the weak reservoir properties, and the weak flow capacity which don't have good connectivity, and the main contact is line contact. During water injectiig, M-type units will be the main oil-rich of residual oilwhich have been poorly produced, and slowly promoted by water. This type units were mainly developed in the high water cut stage. P-type units have mainly distributed in the edge of underwater distributary channel and distributary bay, which sand were thinner, lithology was dense, reservoir properties were weakest, the injected water were difficult to spread and almost had no development value.These studies have shown, E, G, M, P4-type mobile units'features were clear, which have been divided by GAHP. Not only the actual reservoir characteristics has a good consistency, but also have been well verified by dynamic production. Therefore, the results of division of flow units will provide a reliable geological evidence for further tapping and development programs of oil field.