Xiasiwan Oilfield Chang₂ High Water Cut Reservoir Oil And Water Balance Stable Production Controlled By Faces-potential-source Coupling Research

This thesis has researched the phenomenon that Chang 2 oil-bearing formation has high water cut, around 90%, and has been the main producing layers for more than 30 years in Xiasiwan. On the basis of the theory of the petroleum geology, introduced the theory and method of the advanced petroleum system, and by means of geology investigations, which combined with collection and analysis of various data, this thesis has done the researches of the small layer contrast of the Chang 2 reservoir formation, the rules of distribution of the sandstone, structural characteristics, sedimentary micro faces, reservoir properties, and reservoir enrichment factors. Thus we revealed the principle of high water cut, low producing and stable producing of Chang 2 reservoir controlled by faces-potential-source coupling. The main results and understandings are as follow:1. The Chang 2 reservoir has divided into Chang 21, Chang 22 and Chang 23 three parts. The Chang 22 formation divided into three small layers. The Chang 22-3 layer is the main reservoir, and the Chang 22-2 layer is the sub-main reservoir. The Chang 22 formation is ultra-low~ super-low permeability reservoir.2. The braided river depositional system is the main sedimentary system of Chang 2 reservoir in Xiasiwan Oilfield. The Chang 2 reservoir mainly developed channel sand dam, channel sand dam side edge and floodplain sedimentary micro faces.3. The Chang 2 high water cut reservoir in Xiasiwan Oilfield has five geological causes. They are natural fracture system cause, porosity cause, permeability causes, hydrocarbon closure cause and formation water cause.4. According to the theory of the petroleum system, we researched the environment and process of sedimentation of Chang 2 in Xiasiwan on macro mechanism. We worked out four charts and one form of petroleum system preliminarily. We have searched out the special structure system which formed in the whole sedimentation of Chang 2, which contribute to the stable mechanism of water supply.5. According to researches, the source of Chang 2 still comes from Chang 7. Xiasiwan oil field has stable mechanism of oil supply owing to it near the heart of the lake. Thus the phenomenon that stable water, oil, production of Chang 2 reservoir which controlled by faces-potential-source coupling has been brought up.