4D Seismic And It's Application To The Monitoring Of Water Flooding Reservoir

4-D seismic is a kind of reservoir monitoring technique which acquires and analyzes multiple seismic surveys repeated at the same site during the period of production in order to image the changes in a producing reservoir. It utilizes the knowledge of seismology, petrophysics and reservoir engineering comprehensively. There are some important methods such as the repeatability of seismic acquisition and processing, time lapse seismic interpretation and analyses. Based on a vast amount of literature study on 4-D seismic and the investigation of petrophysical properties in BuoHai Bay areas, the author implemented a pilot research about 4-D seismic in a water driven reservoir in Gao29 fault block. The research contents include the foundational research on petrophysics, the feasibility of 4-D seismic in water driven reservoir, pre-stack and post-stack 4-D seismic data processing, static reservoir description, 4-D seismic interpretation and dynamic reservoir description. Through comprehensive study, the author has made some successful achievements as follows.Firstly, the author read a lot of papers which are related with 4-D seismic; summarized the basic concept, research objective, study contents, detailed procedures, the function and the challenge of 4-D seismic. The author also analyzed the overseas situation of water driven 4-D seismic thoroughly; compared the geological condition and production patterns between in China and in foreign countries. Through all the above efforts, the author indicated the importance in water driven 4-D seismic research in China.Secondly, concluded the calculation process of fluid substitution. Based on the analyses of coring data and the full waves sonic log data in BuoHai Bay areas, the author summed up all the petrophysical parameters and settle foundation for the realization of fluid substitution. Focusing on the analyses of the influential factors (such as pressure, temperature, porosity, and the properties of pore fluid) on the velocity, the author provided powerful basis for the feasibility analyses of 4-D seismic.Thirdly, made a careful and completely study on the feasibility of water driven 4-D seismic. According to the analyses of the research results about the feasibility of 4-D seismic and the successful 4-D seismic cases of foreign companies, the author put forward the suggestions for 4-D seismic pilot area selection; briefly analyzed the influential function of producing way on the seismic response; utilized theory calculation, coring data analyses, and reservoir numerical simulation to define the fluid substitution effects on the p-wave velocity. Through long time water driven to the reservoir, some of the properties and the log curves have changed, the author tried to find the variation rule of the reservoir and its effects on seismic velocity. The "blind point" in 4-D seismic feasibility study both in China and overseas was found, that is the lack of consideration of the influence of physical property variation by long time water driven on the seismic response. This found richen the study contents of 4-D seismic feasibility. Applying this research result to G29 fault block, obtained some new ideas about 4-D seismic feasibility study. The conclusion is that it is easier using 4-D seismic to monitor the change of flooding front than to monitor the change of the reservoir. Based on this result, the author proposed five solutions that can easily find the subtle variation by 4-D seismic.Fourthly, summarized the methods and the principals for pre-stack and post-stack 4-D seismic data processing; proposed the criteria for seismic data process; built a set of processing flow. Through the real data processing (029 fault block), obtained reasonable results. Theprocessed result was approved by the further production well.Finally, using the static reservoir description as the basis, pre-stack and post-stack 4-D seismic data processing result as the constraint, the 4-D seismic feasibility study as the evidence, began basic dynamic reservoir description in order...