Key seismic techniques for predicting deep marine carbonate reservoirs and the effect analysis:A case study on the Sinian-Cambrian reservoirs in the Sichuan Basin and the Ordovician reservoirs in the Tarim Basin

The seismic characterization of carbonate reservoirs with the quantitative prediction at its core is key to reserve growth and production enhancement.Petroleum exploration and development in China have formerly been focused on middle-to-shallow terrestrial clastic rocks.In the past two decades, deep marine carbonate rocks, however, start to shine with the discovery of Tahe, Puguang, Anyue and other large-scale gas fields in the west of the country.In comparison to other countries, the deep marine carbonate reservoirs in China are generally characterized by more complex surface conditions, longer history, and higher heterogeneity, all of which have posed significant challenges to quantitative reservoir prediction.Based on the practices in the Ordovician fractured-vuggy reservoirs in the Tarim Basin and Sinian-Cambrian reef-shoal reservoirs in the Sichuan Basin, we systematically expound on seismic prediction approaches and key supporting technologies targeting at dealing with the difficulties specific to the two types of deep carbonate reservoirs.With continuous progress in technologies such as seismic acquisition with "wide azimuth and broadband as well as high density" (2W1H), high fidelity and broadband data processing for well control, pre-stack impedance inversion constrained by sedimentary facies and other key technologies, the reservoir prediction of deep marine carbonate rocks in China has changed from qualitative description into semi-quantitative prediction, and from simple description into fine depiction of reservoir flow units.The study is also of guiding value to the fine development of carbonate reservoirs in both China and other countries. © 2021, OIL & GAS GEOLOGY Editorial Board. All right reserved.