Application Study Of Sequence Stratigraphy On Subtle Oil-Gas Trap In Raoyang Depression

Raoyang depression is located in the middle of Jizhong depression in eastern China. It is a typical fault basin. Complex Reservoirs were developed from several sets of hydrocarbon Source rock, reservoir and seal fonnations. But most reservoirs have been explored and developed. In fact, the amount of production from most structural traps began to decline in recent years. Subtle stratigraphic traps have become the main object of exploration. This paper discusses some new approaches for subtle stratigraphic traps using sequence stratigraphy. The work began by collecting past papers, analyzing various schools of views, theories, methodologies together with the geologic characteristics of this area. After the sequence stratigraphy studied in Raoyang depression, we summarized the law of subtle reservoir and the precision of prediction is improved, so as to make the subtle reservoir research technology perfect increasingly, we have obtained some results in terms of sequence stratigraphy of the Raoyang Depression:1. Using the principle of sequence stratigraphy, seismic characters, regional tectonics, sedimentation cycles, coupled with large amount of logging data, we have clarified the characteristics of sequence boundaries, and identified various sequence boundaries, and partitioned sequence information units, thus formed the framework of the Sequence stratigraphy.2. Through detailed analyzing structures of sequence boundaries, combined with geological understanding of the area, we have re-studied the characteristics of the regional tectonics, stratigraphic developments and the reservoir developments.3. Using logging data, core, and seismic data, we have re-classified the systems tract with the isochronous framework. We also demonstrated the internal characteristics of sand body by the partition of sediment micro-facies, which provides even further understanding of sedimentation system and facies.4. Focused on a key formation (middle of Es3), developed high-frequency sequence stratigraphy, and researched the regularity of the distribution of oil-bearing Sand, thus predicted the reservoir sand distributions.5. Through study of the relationships between the regional sequence stratigraphic framework and the distribution of hydrocarbons, it clearly pointed out the positions of source rocks, reservoir rocks. Thus we come to the recognition that the transgressive systems tract controls source, lowstand systems tract and highstand systems tract control reservoir and sequence boundary controls the trap.6. It was able to predict the regularity of subtle trap distributions, and pointing out the favored areas for the subtle reservoirs by various information and method, and therefore selected six subtle reservoir traps as future exploration targets.It becomes very important for the research of sequence stratigraphy on the basis of an integration of the sequence stratigraphy, sedimentation system and stragraphy facies analysis. Only this way can it have large impact on the exploration and development of oil and gas distribution. This study uses the principle of sequence stratigraphy as the basis and obtained some knowledge of subtle traps in the Raoyang depression which can be used for Oil and gas exploration for similar areas.