Application of Poisson impedance for identification of sweet spot in the Paleogene low-permeability sandstone reservoir in Lufengnan Sag

The lateral heterogeneity of Paleogene reservoirs in the Lufengnan Sag of the Pearl River Mouth Basin is obvious, and the sedimentary and diagenetic evolution is complex. Finding “sweet spot” reservoir with economic productivity is the key to efficient exploration of the Paleogene reservoir. Based on petrophysical analysis and coordinate rotation, it is clear that Poisson impedance is the most sensitive elastic parameter to identify “sweet spot” reservoir. By the Co-Kriging low-frequency modeling, the prestack elastic parameter inversion was carried out, from which and the relevant elastic parameters were obtained directly, and then the elastic parameter dataset including Poisson impedance was constructed, based on which the quantitative interpretation and prediction of sandstone reservoir and "sweet spot" reservoir were performed. The inversion results show that the distribution of the “sweet spot” reservoir of Wenchang Formation is obviously controlled by the sedimentary facies. The lithology is mainly microfacies sandstone indicative of underwater distributary channel, and the characteristics of sedimentary facies are consistent with the drilling data. The application of this technology and method can realize the transformation of Paleogene “sweet spot” reservoir exploration from qualitative to quantitative determination, improve the success rate of deep exploration in the Paleogene, and provide a strong support for increasing reserves and production in the Paleogene.