Geophysical approach to improve well correlation and stratigraphy package in the frontier area: example case of Upper Jurassic Fm. Semai Basin, Eastern Indonesia

Abstract

Well correlation needs to be done carefully in the exploration phase. In this study, due to a limited biostratigraphy data, the alternatives approaches to improve the well correlation were conducted. The approach is known as an Integrated Prediction Error Filter Analysis (INPEFA). The method generates a predicted Gamma Ray (GR) log based on the auto-regressive model. INPEFA generate and extract major sequence information curve and give the clue to the interpreter to get the general frame of correlation. INPEFA curve idea is related with sedimentation cycle where the package of sediment consists of para-sequence set and the para-sequence is formed by lamination, and so on. This phenomenon is known as an order of sequences. For the case study, the method is applied in to the frontier block located in Semai basin in the eastern of Indonesia. Six wells are included in to the analysis to be correlated by combining limited biostratigraphy data and INPEFA curve. The results conclude that the correlations from five wells have identical of eustasy cycle pattern, and validated by biostratigraphy marker. The correlation also show that the thickness of reservoir sandstone in the Upper Jurassic Formation increase to the north direction.