Flow Unit Research Of Chang 2 Reservoir In Tanjiaying Area Of The Ansai Oil Field

To the reservoir geology and development feature of Ansai Oil Field, Tanjiaying Area, this paper utilizes a series of modern oil reserve description technologies and methods, which are geological comprehensive analysis, oil deposit 3-D modeling and remaining oil saturation and the like on the basis of comprehensive analyzing oil reserve geology, well logging, reservoir petrology geology, modern sedimentology, reservoir geology, oil exploitation geology and oil reserve engineering as guiding theory, uses computer technology, has a research on reservoir flow unit of Chang 2 oil reservoir in Tanjiaying Oil Area, Ansai Oil Field, and put forward the distribution rule of remaining oil controlled by formatting unit. The main achievement of this study is:1. Though detailed division and correlation of strata, Chang₂¹ in te original three oil sub-formation of study area is parted into anther three reservoir section, includes Chang₂^1-1, Chang₂^1-2, Chang₂^1-3. The data base of strata has been built. According to it, the tectonic diagram of every small stratal roof-to-floor surface has been completed, analyzed micro-scale structural feature of this area at the same time.2. Combining regional geological setting and the sedimentary facial character of Chang 2 oil reservoir in Tanjiaying Area, what has been determined as braided river is further parted into three micro faces, including channel sandbar, washland, interstream depression, and explained its space-time evolutionary regular pattern, the micro face of channel sandbar is the main reservoir bed of this area among them.3. Research on reservoir anisotropy from intrastrata, interstrata and plane represents: Small channel sand bodies are well-developed and have a strong connectivity, oil saturation and drilling encounters have a high value, Chang₂^1-2 is the main reservoir while Chang₂^1-3 is the sub-main layer. The changes of permeability are dominated by sedimentary micro faces. On the whole, all the intrastrata, interstrata and plane of Chang 2 oil layer have a strong anisotropy.4. This paper has discussed the concept of flow unit and its genetic influencing factor. Flow unit is defined as a reservoir unit, which is continuous on longitudinal and cross, has the same characteristic parameter that can influence fluid flow. It is reservoir unit has similar lithology and physical property in reservoir layer. The reason and influencing factor of flow unit mainly include sedimentation, diagenesis, tectogenesis and fluid character of reservoir.5. It puts forward the divided principle of flow unit: Step subdivision comparison, isochronous surface comparison, cyclic grading comparison, optimization principle, divisibility principle, comprehensiveness principle, rationality principle and practicability principle.6. The flow unit are divided into 4 types by means of clustering analysis. Through the study of characteristic parameter used to symptomize fluid unit, this article makes porosity, permeability, effective thickness and the like as characteristic parameter to symptomize flow unit, completed corresponding interpretation and evaluation model of well logging.7. The space distribution character of flow unit in this area has been put into research, and in contrast to physical property and sedimentary micro-faces of these reservoirs. The better of flow unit, the thicker of sand body, the higher of porosity and permeability, the higher of oil saturation. Sedimentary face has a controlling effect on the distributon trend of flow unit. But the same micro face can be divided into different flow unit due to the vadose differences in it. So their distribution not only has same trends but also has differences.8. Through studies on the 4 types of flow unit in this area, we concluded that the distribution area of C type flow unit is the main remaining oil rich field and further developing and potential field of this area.