High-resolution sequence stratigraphy research based on continuous wavelet transform and INPEFA - A case study in the Kalashayi formation, Tarim Basin, China

Abstract

The Carboniferous Kalashayi Formation, situated in the Lungu-Sangtamu area within the Tarim Basin, exhibits protracted sedimentation periods, intricate sand-mud depositional sequences, and scant paleontological and core datasets. Precision in delineating high-resolution sequences using conventional core and logging data poses a considerable challenge. To enhance the stratigraphic accuracy of the Kalashayi Formation in the Tarim Basin and facilitate quantitative analysis, this study employs continuous wavelet transform on the gamma ray (GR) curves obtained from core wells within the study area. Subsequently, various sequence boundaries are discerned by integrating the resulting wavelet coefficient curves with time-frequency energy maps. Discrimination and subdivision of base-level cycle structures of varying orders are achieved through temporal trend analyses of integrated prediction error filter analysis (INPEFA) curves. Integration of drilling, logging, lithofacies, and core data enables the identification and subdivision of high-resolution sequence stratigraphy using wavelet analysis and INPEFA techniques. Ultimately, the Carboniferous Kalashayi Formation in the Lungu-Sangtamu region is classified into 2 long-term, 5 medium-term, and 14 short-term base-level cycles, establishing a meticulously delineated isochronous stratigraphic framework. This framework serves as a fundamental basis for subsequent discussions on reservoir prediction within the study area.

Keywords

• High-resolution sequence stratigraphy
• CWT
• Lungu-Sangtamu block
• INPEFA