High NCG Wells Interference Test for High NCG Wells Optimization in Salak Geothermal Field

Abstract

The steam cap has significantly developed in East Salak resulting to dry steam production and higher Non- Condensable Gas (NCG) content in the most of East Salak wells, particularly Pad A and M- wells. Nowadays, Unit- 4 experienced frequent curtailment (loss generation) due to high-NCG steam supplied by Pad A wells. Steam blending (among high- and low-NCG wells) was initiated by shutting-in or throttling high-NCG wells in order to maintain NCG content in Unit-4 below the maximum Gas Removal System (GRS) capacity (2.25wt.%). Unfortunately, this method did not give consistent results due to NCG interference among Pad A and Pad M wells. NCG Interference was first evaluated in 2012 by observing changes in NCG concentration of certain wells after new make-up wells were POP’d or the existing wells were shutted-in. Another NCG interference evaluation was conducted on January 2014 – May 2015 to observed the optimum operation setting of high-NCG well in Pad A. However, several well still showing uncertain connectivity and camouflage by interference with other wells (Julinawati et al., 2017). Thus, an ideal interference test is needed to fully understand the NCG interference of high NCG wells. The ideal condition mentioned here is the condition where we only change 1 well per event and monitor the changes at surrounding wells. The NCG interference test was completed in 31 days operation and comprehensively shows clear NCG interference among Pad A and Pad M wells. This test result is used as reference to develop operational guideline of high NCG wells in Salak Geothermal field.