The Study Of Subtle Reservoir Prediction Technology Of Baiyinchagan Basin

Under the background of difficult situation in structure reservoir exploration and initial success in subtle reservoir exploration in Baiyinchagan Depression, the research in subtle reservoir prediction was conducted in this dissertation, facing the complicated seismic and geological conditions, such as breakage structure and fast changing reservoir, and guided by sequence stratigraphy and seismic sedimentology, the research in this dissertation focuses on the seismic data's ability to solve the geological problems and was based on the geophysical characteristic analysis for the single well, the seismic attribute analysis, the non-linear constraint inversion and several other geophysical means were used to integratedly identified the subtle reservoir, a set of techniques and means which fit the subtle reservoir exploration was established, excellent results were achieved by applying the techniques and means in oil&gas exploration in Baiyinchagan Depression. The following conclusions were obtained in this dissertation:(1). By jointly using well logging data and seismic data, the high precision sequence stratigraphyic correlation and studies were conducted, the united well-seismic sequence framework was established, based on the theories and methods in seismic stratigraphy and logging geology, the types of sedimentary facies for different periods, the distribution of the sediment system and the sedimentary microfacies in the key areas for the Depression were studied in detail, the temporal and spatial distribution of the favorite sedimentary facies belt was determined.(2). By utilizing some integrated interpretation techniques, such as 3d visualization, coherent volume analysis, spatial velocity field and balanced section, the integral interpretation and mapping for the 800 square Km merged seismic data were conducted, the controlling relation of the structure development evolution characteristics and the palaeotectonic setting to the development of the sedimentary system, their relationship with the distribution of the subtle reservoir were analyzed, laying a solid foundation for the potential targets for the subtle reservoir exploration.(3). The new wavelet frequency splitting processing method was used to conduct frequency expanding processing for the post-stack data, the vertical resolution was then greatly raised, which was conducive to the thin-layer's identification, the dominant frequency of the field seismic data was raised 10 Hz, the frequency band was expanded 45 Hz, excellent results were achieved. In seismic inversion, the structure&horizon controlling thought in the modeling method and the well constraint extrapolation algorithm were jointly utilized, the advantages in the linear inversions, such as the broadband constraint inversion, the logging constraint inversion and the modeling method inversion were absorbed, at the same time while conducting non-linear inversion, the structure-well constraint well extrapolation inversion was utilized, as a result the structure-well constraint non-linear high precision seismic inversion technique was formed. The processing results for the field seismic data show that the method is stable, the inversion results have high apparent resolution and high signal to noise ratio, the reservoir predictions for the key areas were conducted by using the method, it can resolve 3 - 5 meter thick reservoir, the matching rate with the drilled wells reached 85%.(4). The technical series for subtle reservoir prediction for the Baiyinchagan Depression was formed in this dissertation, which could guide the oil&gas exploration in the Depression, the new discoveries and sustainable developments for the subtle reservoir exploration in the Baiyinchagan Depression were realized. By applying the technical series the lithology- structure light oil enriched zone in slope zone of Xilinhaolai were identified with proved reserves of 3 million tons, the 10 million tons reserves of heavy oil in overlap zone of Xilinhaolai were initially implemented, it was found out in the research of the dissertation that the several types of subtle reservoir, such as the stratigraphic reservoir, the lithology, reservoir and the structure-lithology reservoir exist in the Baiyinchagan Depression. 13 subtle traps were identified altogether, it was proven by the drilling that the technical series was feasible.