Comprehensive Tapping Residual Oil Potential of Strong Water Drive Mature Oilfield in Southern American Rainfall Region

Abstract

Abstract Yanayacu Oilfield in Block 1AB/8 belongs to strong natural water driving oilfield with over 30 years development history in Peru rainfall region. The comprehensive water cut is 95% by 2005. This paper reviews a multidiscipline comprehensive study on potential tapping in this oilfield. Based on re-explained reservoir structure and secondary logging interpretation, as well as comprehensive geological study, fine reservoir 3D model was built and residual oil distribution was characterized. Reservoir simulation is conducted and result shows well pattern is the dominant controlling factor of residual oil. The well spacing is about 750–1000m, and there is no well drilled in structural high part in the north region, which leads to relatively enriched residual oil potential in the structural high part. The residual oil distribution is also affected by interlayer and barrier. According to residual oil distribution result, horizontal wells were deployed in relatively structural high part to tap residual oil, and re-perforation, layer transformation and bridge plug were applied in high water cut wells with interior barrier and interlayer. According to adjustment plan, two horizontal wells and one directional well were drilled in 2006, where the initial production of two horizontal wells is over 3300bbl/d, which is over 5 times of the highest initial production of previously drilled wells in this field. The comprehensive water cut of this field is dropped from 95% to 89.5% by the end of 2008.