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Application And Research On Reservoir Prediction In Tight Gas Sand

Posted on:2010-05-01Degree:MasterType:Thesis
Country:ChinaCandidate:W ZhangFull Text:PDF
GTID:2120360272987758Subject:Earth Exploration and Information Technology
Abstract/Summary:PDF Full Text Request
With the development of the extension of exploration, most of oil-gas fields in our country are in the later exploration stage. The main aim transferred from detecting structure oil-gas reservoir in earlier times to discovering lithology reservoir. Additionally, besides the common sandstone and carbonate reservoir, the unconventional gas-bearing tight sand reservoir, igneous rock and fracture mudstone which have abundant resources have became significant exploration field.Northeastern nonmarine formation in Sichuan Basin is a typical tight sand reservoir. Because the marine carbonate formations which are the main pay formation are the chief study and research interesting formations, the study extent of nonmarine formations is comparatively low and has finite understanding. The well logging of the terrestrial formations displayed abundant oil-gas in Northeastern Sichuan Basin. The potential exploration discovery in this region is enormous. And the prospecting and delineation of gas-bearing tight sand reservoir is the core of study thesis.The thesis summarized the current status of research and development of tight sand reservoir prospection in domestic and overseas. Take the upper Triassic Xujiahe fourth formation of dense gas-bearing sandstone reservoir which are continental sedimentary in the northeast of Sichuan as an applied example. The reservoir prospection is carried based on 3D seismic data. The interesting formations have features of tight sand reservoir such as the thin thickness of layers, low porosity, low permeability, heterogeneity and great differences in the abundance of gas and so on. There are great difficulties in seismic reservoir prediction.Firstly, the acoustic log curves are not sensitive to the response of sandstone and mudstone. These may not well distinguish lithology or determine formations. Based on these characteristics, the author applied pseudo-acoustic method to setup well log curves which are sensitive to lithology. Take these curves as controlling points to establish primary model. Appling seismic inversion constrained by wells to do seismic inversion based on the model. Meanwhile, spectral imaging technology is applied to prospect the plane and spatial distribution of the reservoir in the target area. Secondly, a series of seismic attributes (such as amplitude, instantaneous frequency, instantaneous phase, frequency spectrum, the largest energy, etc) have been extracted based on the reservoir prediction. After analyzing the extracted seismic attributes, the author discovered that the absorption attenuation property is more sensitive than the other attributes to the fluid response in the region. So that this method was used for predicting the possibility of the existence of oil-gas in target area, and ultimately establish the favorable plane distribution of the reservoir.In conclusion, the thesis applied the results of three methods of reservoir prediction: reservoir seismic inversion, spectrum imaging and seismic attribute analysis. Meanwhile the author combined geologic background and structural characteristics to process research on spatial distribution characteristics of the interesting formation and comprehensive analysis on characteristics of the interesting formation and comprehensive analysis on characteristics of fluid development in Xujiahe fourth formation in northeastern Sichuan. The results of prospection are well matched with known drilling data. All of these provide preliminary basic reasons and reference for the next step exploration and study in this region.
Keywords/Search Tags:tight sand reservoir, pseudo -acoustic, seismic inversion, seismic attributes, absorption attenuation
PDF Full Text Request
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