Study On Integrated Prediction With Geologic And Seismic Methods For Jurassic Reservoirs In Santanghu Basin

The Jurassic formations are investigated at Niuquanhu area in Santanghu Basin. The technological theory and the methodological workflow of reservoir prediction comprehensively integrated with seismology and geology is discussed focusing on study of reservoir prediction methods and comprehensive seismic reservoir prediction technology in this dissertation. Hi-resolution seismic, geology, logging, drilling and other kinds of geologic information are applied to the Jurassic reservoir with serious heterogeneity at Niuquanhu area for studying the reservoir prediction and hydrocarbon detection for seeking potential reservoir and hydrocarbon play. The goal of the study is to probe a suite of effective comprehensive reservoir prediction technologies for special geologic settings, which improves the accuracy of reservoir prediction and hydrocarbon detection, and guides the future oil and gas exploration.The boundary surface of Jurassic sections of formation is identified based on the theory of sequence stratigraphy combined with seismic data, logging data, drilling core and other geologic information. The stratigraphic correlation and classification are performed combining with single well to seismic data from points to plane and from the analysis on individual well of sequence stratigraphy to study multiply wells of sequence stratigraphy. The study shows that the Jurassic strata are classified as six sequences and three oil-bearing intervals. Thus the framework of Jurassic sequence stratigraphy is established at Niuquanhu area. The sedimentary facies features and patterns, and the spatial and temporal distribution characteristics at the Jurassic are invested and obtained the map of horizon and spatial position of favorable reservoirs based on the core description and the seismic data, geographic logging, well logging. The results suggests that there are four types of sedimentary facies as fan-delta, braided river delta, lacustrine and fluvial facies at the area with a sedimentary evolution character of two large scales of transgression and regression sedimentary at longitudinal direction. It is conclude that three Jurassic hydrocarbon reservoirs are primarily subject to the corresponding sedimentary facies, and the optimistic reservoirs should be the fluvial channel sandbody and the distant sandbar in the delta front facies.The analytic results of sedimentary faies and the characters of reservoirs are adopted for the study of reservoir geology. Multiform seismic technologies such as hi-resolution wave impedance inversion, seismic attributes, seismic spectral decomposition and hydrocarbon detection are utilized to the integrated reservoir predication. The overall study demonstrates that the reservoir sandbody occurs in the form of multi-layer and multi-side overlapping with a stable distribution, forming the basis of lithologic traps. Therefore favorable reservoir belts and abnormal distribution zones of hydrocarbon are set on, of which five abnormal zones of gas pool with a total area of 28.2km~2 in Qigu formation, one abnormal zone of gas pool with a total area of 3.6km~2 in Toutunhe formation. It is predicted that a packaged oil pool with an area of 62.8km~2 has been confirmed in Xisanyiao formation. Two target wells are optimized for drilling through integral analysis on the favorable targets.The integral technology for reservoir prediction used in the study is superior in the high prediction accuracy. Seismic data shows that 10m reservoirs of thickness can be identified longitudinally; and drilling results suggest that the distribution range of the oil layers and the abnormal zones in Qigu and Toutunhe formations predicted horizontally are consistent with the actual geological setting.