Seismic Reservoir Predicting In Zizhou-Qinjian Area Of Ordos Basin

Zizhou area is another profitable area after discovery of Yulin gas field. Thesecond member of Shanxi formation is main reservoir which is composed of channelsand body of delta plain and mouth bar of delta front. Thickness of reservoir variedfrom several to dozens of meters. Channel migrated frequently in lateral. In vertical,Several times sand body lapped over. Meanwhile, porosity and permeability are prettylow, and this kind of reservoir belong to high heterogeneous reservoir.Object to these key-point, rock-physics analysis and seismic forward modelingare used as basic method to research geo-physics response of gas-bearing sand.Seismic inversion and hydrocarbon detecting are used as major tools to predict thedistribution of favorable area. The cause and distribution discipline are also analyzedin this paper. At last, following conclusions are got.(1)Rock physics analysis indicate that sandstone of second member of Shanxiformation's impedance is high. There is a big impedance difference between puresandstone and shale, coal, however, impedance of shaly sand and siltstone are so close,it's difficult to distinguish them by impedance. Density and GR are effectiveparameter to distinguish them.(2)Seismic forward modeling is used to simulate transmission of primary wave.Reservoir is divided into three types according to reflection of wave, and it canpredict the thickness of reservoir qualitatively.(3)Colored inversion is used to invert impedance, and it can predict lithologichydrocarbon reservoir with high heterogeneous. We circle the thickness of reservoiron impedance inversion section quantitatively. Neutral network is used to invertsaturation, We can interpret saturation of reservoir.(4)We interpret distribution range of hydrocarbon base on elastic wave's energywill be absorbed and attenuate during transmission.(5)Thickness of sandstone is circled on impedance inversion section.Hydrocarbon is detected on saturation inversion section and absorption attenuationsection. We predict gas bearing sandstone combining three kinds of inversion section. At last, favorable zone is picked out on planand also evaluated.