A target-oriented integrated workflow for seismic delineation of thin tight reservoirs in the eastern Sichuan Basin, China

Abstract

Complex lithology association along vertical direction results in thin layers with different interbed patterns of the Lower Triassic Jialingjiang Formation (T 1 j), Sichuan Basin. The prediction of thin tight reservoirs in the Jialingjiang Formation is important for further oil and gas exploration. However, seismic data in the eastern Sichuan Basin has poor lateral continuity of seismic events because of strong interference noises, which makes it difficult to pick horizons. Moreover, low dominant frequency (<25 Hz), low seismic resolution, and weak response characteristics of strong transverse heterogeneity on logging parameters make it challenging for the thin reservoirs prediction. To tackle these issues, in this study, we propose a target-oriented workflow by integrating seismic data processing with interpretation to delineate the thin reservoirs and corresponding hydrocarbon production capacity. In the processing workflow, we first remove the noise interferences using the structure-oriented filtering (SOF), which can improve the effective information of seismic events and also preserve the features of fault structures. Second, we propose a novel method based on spectral shaping and sparse inversion to enhance the seismic resolution. Tests on filed data demonstrate that the effective information and resolution of processed seismic data are significantly enhanced. Then, in the seismic interpretation, fluid mobility and spectral decomposition are first used to delineate the spatial distribution of favorable reservoirs. Furthermore, multi-attribute integrated interpretation involving impedance analysis, reservoir thickness estimation and porosity inversion is used to evaluate the storage capacity and productivity of the thin reservoirs. The estimated impedance, reservoir thickness and porosity show good agreement with well information, demonstrating the feasibility of the proposed method for accurately predicting thin reservoirs in this area. Multi-attribute integrated interpretation revealed that the favorable thin reservoirs are mainly developed from the northeast to the southwest in the study area, which can provide effective guidelines for future production well drilling and distribution delineations of a favorable reservoir in the Eastern Sichuan Basin. • Structure-oriented filtering (SOF) can remove noises and enhance the effective continuities and structural features. • A new resolution enhancement (RE) method improves the seismic resolution significantly and reduces the artifacts. • The target-oriented processing workflow can markedly improve the quality of the seismic data. • Multi-attribute analyses indicating the favorable thin reservoirs is developed for the target zone.