Application of pre-stack elastic parameters inversion and FFP analysis techniques in the exploitation of A gas field, East China Sea

The main reservoirs of A gas field in Xihu sag of East China Sea Basin are sand bodies deposited by distributary channels of the shallow delta, with quick lateral variation and strong heterogeneity. Therefore, it is risky in the implementation of development wells. Moreover, the P-wave impedance values of sandstone and shale in the target layer are superimposed, so it is impossible to distinguish the lithology and detect hydrocarbon based on the attribute analysis of post-stack seismic and P-wave impedance inversion technology. Based on the determination of lithology and fluid sensitive elastic parameters by rock physics analysis, the authors predicted the lithology by the pre-stack elastic parameter inversion technology, and quantitatively predicted the probability of hydrocarbons by FFP analysis technology. These two techniques have achieved good results in the development of A gas field. The main channel sand body shape was clearly depicted by the v_p/v_s obtained from pre-stack inversion, which guided the optimization of horizontal well and resulted in high sandstone penetration rate of 95%. The spatial probability distribution of gas-bearing sand bodies as predicted by FFP analysis based on the combination of v_p/v_s and P-wave impedance, so the potential gas reservoirs were predicted and the adjustment well was guided to tap the potential gas successfully. These two techniques have good application value for reservoir description and potential hydrocarbon prediction of P-wave impedance superimposed reservoirs in the oil and gas field of East China Sea.