Production Decline Analysis of Dry Steam Wells in Wayang Windu Field

Abstract

In Wayang Windu Geothermal Field, production decline of dry steam wells was previously evaluated by filtering the production data using wellhead pressure range. However, it is found that the validity of the filtering method is limited to short period of time and becomes invalid if the well head pressure has dropped below the pressure range used for filtering. Production history of dry steam wells in Wayang Windu was then examined with a formulation developed by Acuna (2010). Through the examination process, the formulation is deemed reliable to be used for well decline calculation. Seperate calculation of wellbore coefficient (CWB) using wellbore simulation is required in order to calibrate the well productivity index (PI). Two examples are given to demonstrate the application of Acuna formulation to evaluate some cases in Wayang Windu, related to well deliverability reduction due to tie-back work over and abnormal decline due to scaling