The Research Of Seismic Reservoir Prediction Method And Analysis Of Application Effect In Qibei Slope Of Qikou Sag

Along with the more and more importance of the lithologic reservoir in exploration and exploitation of the oil/gas, and the improvement of3-d seismic acquisition instruments, the development of data processing technology and comprehensive application of various interpretation methods, more and more seismic datas have been used to research reservoir prediction methods in a large number of practical production in recent years.Located in the southwest of Qikou sag, the more order flexure of Qibei slope is northeast long-term development of the slope structure. Because of the influence of sedimentary environment and water into background, the study area which form a large number of lithologic traps and stratigraphic traps is a typical developing area of lithologic oil and have potential to oil and gas exploration.The shahejie group formation of the high and middle Qibei slope and the Esl group formation of low slope are the main exploration stratum in Dagang oilfield, which has found ZhouQing Zhuang、WangXu Zhuang、MaDong oilfields etc, but these oilfields mainly concentrated in the high places and both sides of the slope broken nose area, the exploration degree of real slope structure was low. In addition,the different stratums and different parts of the same stratums, these are different in sand body development degree and enrichment regularity. The geological characteristics are reservoir with complex lithology changing、heterogeneity and single sand body with thin thickness etc. The main features of the reservoir of study area are concealment and complexity,which are difficult to predict. Therefore, it is difficult to obtain good results by geological method alone in the reservoir prediction of the thin reservoir description and effective prediction. If we want to achieve good prediction effect, it is necessary to effectively combine the geology、well logging and seismic, which are demanded comprehensive analysis and research.This article systematically researched and summarized the methods、principles and application requirements of the existing main seismic reservoir prediction technologies, including seismic attribution analysis technology, seismic inversion technology and stratal slice technology. Based on the principles、methods and application requirements of the seismic attribution analysis technology, it analyzed and studied the seismic attribution extraction and optimization method、introduced the geological meaning of common seismic attributions and summarized the application limitations. About seismic inversion, this paper systematically analyze and contrast the basic principle of recursive inversion and based on model wave impedance inversion. It discussed the existing problems of the two conventional inversion method、analyzed and compared with their features and applicable seismic and geology conditions. This article respectively introduced four slice technologies including time slice(level slice)、horizon slice、stratal slice and stratal body slice. It also summarized the applications and limiting conditions, and distinguished stratal slice with stratal body slice.On the basis of the study in seismic reservoir prediction method, Qibei slope of Qikou sag as the research targt combining with seismic、geology、well-logging datas which ensure different seismic response characteristics of different stratum structure. Under the guidance of the geophysical response analysis, seismic attribution analysis、 seismic inversion and stratal slice were used to interpret reasonable geological cognition. At last, comprehensive use of various materials predict the distribution of good reservoirs.Through studying the principle、methods、application conditions of seismic reservoir prediction technologies and analysis of the practical application effect, it is concluded that the following conclusions:1. In the application of seismic attribution analysis technology, according to the coming extractive seismic attributions and research purpose we should have a pertinent targeted fine structure explanation. It should eliminate regional mark layer、 special geological body etc strong reflex shaft when choosing windows, in order to avoid the extracted attributions cause interference. According to the geological conditions of different regions, the comprehensive use of various ways to choose reasonable attributions or attributions combination. Comprehensive analysis of multiple attribution is the important ways which is to reduce multiple solution of attribution prediction lower risk prediction and improve the success rate of exploration.2. In order to lest influence of multifold material sources which lead to different sedimentary type and large difference of buried deep stratum which cause needless interference, the study area should not be too big when using seismic attribution technology. When we use seismic attribution to predict reservoir in Qibei slope, amplitude class attribution have best correlation with the reservoirs of board1oil group, but the strong reflex of the top board2oil group、shore oil group which have great influence in region, seismic attributions cannot be applied in the reservoir prediction.3. If we want to get characteristic curve which can reflect the change rule of target layer, it is necessary to effectively deal with logging curves which is one of the key to improve the reservoir prediction by using Wave impedance inversion. In the process of the horizon calibration and wavelet interaction iterative, we should consider the wavelet waveform, wavelet frequency band and space change. By using fractional modeling and contrasting analysis of various parameters size, the establishment of an low frequency wave impedance model is closer to actual condition which can avoid modeling and serious distortion.4. The thin reservoir mainly develop in Es2group of the middle Qibei slope and dolomite in parts.It should contrast and statistically analyze the characteristics of the logging curves so as to find out well distinguishing the lithology of logging curve. Beach dam sand body was developed in the region of bins6well, it can use Gamma sound waves inversion to better distinguish mudstone and depict regular pattern of lateral changes of the little sand group. Dolomite reservoir was developed in the region of bins18well, it directly use gamma curve inversion which can be not only used to distinguish mudstone in reservoir, but at the same time effectively eliminate the interference of dolomite and help to implement the development scope of sandstone reservoir.5. Stratal slice and stratal body slice are two different concepts. Stratal body slice by displaying different attributions in the space change to guide stratal study, which truly reflect reservoir in real changes in the space. Stratal slice is simplification、 promotion and extension of stratal body slice and is a continuous horizon slice.6. By using stratal slice technology, we can observe different seismic attributions changes in plane, but not every stratal slice body which are well reflect the geological phenomenon. Just in the area which are good seismic data quality、relatively simple fracture and relatively stable stratum,we can use stratal slice technology that selecting the suitable reference isochronous surface and using all kinds of3d seismic attribution data volume which can reflect the formation change. Combining the practical geological conditions to choose geological meaning of stratal slice, which can well solve problems of sedimentary and reservoir prediction.7. Seismic attribution analysis、seismic inversion and stratal slice are suitable for different seismic and geological conditions, these three comprehensive application play a good complement in seismic reservoir prediction in Qibei slope and provide plenty of reservoir prediction results for comprehensive geological evaluation of target zone and provides the reliable basis for exploration deployment.