Water Injection in Tight Formation with Sensitive Minerals: Lessons Learned From “F” Field

Abstract

Telisa Formation is the second productive reservoir in “F” Field beside Baturaja. The formation, which is familiar as TF, is considered as a tight sandstone containing sensitive minerals. Hydraulic fracturing needs to be done before producing the wells. Producing initially since 2001, TF has been implemented water injection since late 2009. Before its initial implementation, the feasibility study recommends that water injection was feasible to be performed and targeted to increase its reservoir pressure. However, after almost ten years of injection, the cumulative voidage ratio is still low and reservoir pressure could not reach its expected value. Nevertheless, water injection is critical to maintaining reservoir pressure. So, it was decided to conduct another study to evaluate the water injection performance and recommend for further improvement.

The following paper elaborates the evaluation phases and the lessons learned derived from the study. The evaluation phase consists of historical data gathering; mapping the problems; performing the field and laboratory measurement and parallel conduct the analysis. The study covers rock characteristics, surface facilities and geomechanics evaluation.

he result shows that all factors have their contribution to the permeability impairment which creates poor injectivity performance. Main factors, in this case, explain the criticality of reliable separation facilities. As the other eye-opener, the formation also contributes to the loss of strength due to exposure to water injected. When it is weakened, it may multiply the damage in the formation. The study shows that an integrated study gives a comprehensive result and give the options to the management for selecting the desirable outcome.