The Uniqueness of Architectural Transgressive Succession Character of Keutapang Formation to Assist the Increase Production in Rantau Field

Abstract

Rantau Structure is located in Northern Sumatra of Indonesia, a mature structure of PT Pertamina EP that has been in production since 1928, currently there are about 627 wells. The development of this structure focuses on the Keutapang Formation, which largely assumes that the growing sedimentation is the precipitate of delta system deposits in the shallow marine environment (Mulhadiono, 1976).
The development concept of Rantau structures from the beginning of 1928 - 2017 still uses lithostratigraphy concept, and need new methods as follow up development of mature field to be more optimal. With the Concept of Stratigraphic Squeeze Analysis used on the basis of data acquisition consisting of well logs, biostratigraphic data and core data helping to know the growing sedimentary structure and knowing facies in the sedimentary environment, it is useful to see the uniqueness of the transgressive phase in the vertical section and lateral section in this structure. The research method will be applied to see the opportunity of hydrocarbon prospect layer which has never been developed before.
The Transgressive phase under the conditions of the High Stand System Tract at depths of 320 -600 mtvdss are shallow marine - wave dominated deltaic system deposits, represented by sedimentary structures of core P-361 and P-406 cores with typical climbing ripples, wavy lamination, Herringbone, and Hummocky Cross Stratification accompanied by a burrow presence indicating the Neritic - Sub Neritic environment with a growing sediment packages dominated by transgresive
succession.
Production Result from Well Workover P-390 (Z-460B)/FS-4A to MFS-3 Test on 1 Feb 2018, Flow 136.2 BFPD / 136.2 BOPD / 0%WC, and P-449 (Z-360) / FS-7 to TS-7 Test on 6 Feb 2018, FLOW 173.4 BFPD/170.3 BOPD/2% WC are some of the evidences can be concluded that potential layers developed in the form of tidal channel and tidal bars (Transgressive Succession), so it is necessary to optimize production at wells in Rantau structures are primarily in the reservoir packages.