Facies analysis with seismic attribute for net paying sand in late Miocene at Kutai Basin

Abstract One of the challenges faced in exploration field development is many geological factors that are still not well understood regarding reservoir distribution and net pay. Fasies analysis become the key to understanding the characteristics of reservoirs and their distribution. This paper discusses the characterize of the reservoirs through stratigraphy and facies analysis supported by seismic attributes. Biostratigraphy data is used to understand the depositional environment and dividing sequence. Each sequence contains a target reservoir with different facies, caused by different sedimentation rates. The target reservoir was found in the Low-stand System Tract (LST), with the gamma-ray log showing fining upward and some coarsening upward patterns. Based on seismic attributes analysis on different sequences, the facies of the target reservoir are slope-fan and channel with slope-fan facies is thicker than the target with channel facies. The thicker slope-fan contains higher net-pay sand that becomes the main target of reservoir. The slope fan and channel facies appear in parasequence that have higher sedimentation rates, while channel facies only appear in parasequence with lower sedimentation rates. Sedimentation rates play a significant role to determine the thickness and the facies of the reservoir.