Successful Application of Imaginary Stratigraphy Boundary from Production Mapping for Infills Project in Mature Fields, Central Sumatra Basin, Indonesia

Abstract

Locating successful infill wells in mature field is challenging due to dense well spacing and low production performance. Four infill wells were proposed in 2017 to improve oil recovery from 2 mature fields in Rokan Block of Central Sumatra Basin with producing up to 98% water cut. Direct vertical assessment from stratigraphy analysis does not always relate to actual production performance. COWC does not seem to raise up homogenously across the field based on correlation between field structure and well perforation depth. Delineating sweet spot area based on production attribute mapping can assist more reliable stratigraphic imaginary boundary to define surface location and subsurface target for infills. Production attribute mapping is used to qualitatively interpret fluid distribution and potential of current remaining oil in the field. Focus of reservoir objective analysis can be done thru well correlation by posting surrounding well perforation interval and outline area of interest from the mapping above. The drilling result has confirmed that this method works effectively and can be used to justify new infill well projects to prove the concept of bypass oil possibility in mature oil fields. The new wells are completely drilled and POP by April 2018. Production performance from those four new wells are showing incremental production up to 1800 BOPD with average 70% water cut. Result from this simplified approach can also be useful for identifying fluid movement pattern and helpful in avoiding areas that would yield poor infill drilling results.