| Abstract |
In Darajat asset, West Java – Indonesia, Chevron operates steamfield that supplies Chevron’s two units of power plant (Unit II and III) and one power plant owned by national electricity company (Unit I). Unit II and III main steamline have a common pipe header which is equipped with 18” NPS of hydraulic actuated ball valve for each unit to control interface pressure (Pressure Control Valve). By design, the interface pressures are controlled to 16 bar(a) for Unit II and 17.27 bar(a) for Unit III. As the Unit III has the highest interface pressure, operation of the Unit III PCV sets the common pressure upstream of both the Unit II and III PCVs. With current condition where upstream PCV pressure is 19.6 bar(a), the pressure drops calculated across Darajat Unit II and Unit III PCV station are 3.6 bar and 2.3 bar respectively. Reservoir model has shown that reducing pressure drop across PCVs can allow the wells to produce at lower well head pressure, and this may impact to decline rate reduction. The debottlenecking process is to be done in two stages. For the 1st stage, Unit III PCV is to be debottlenecked by installing parallel PCV to reduce the pressure drop by 1.04 bar. At the 2nd stage, in order to reduce the pressure drop of Unit II PCV, Unit III header must be separated from Unit II by modifying the interface header to dedicate the steam line, and then it is followed by installing parallel PCV of Unit II to further reduce the pressure drop of Unit II PCV by 1.7 bar. From reservoir model, the surface facilities pressure drop reduction resulted by this series debottlenecking project can lower decline rate from 9.32% to 7.64% thus benefit the company from deferring 11 makeup wells drilling. Lessons Learned:* Describe any lessons learned as a result of the activity described in the abstract. Maximum 500 characters. • This project has been a show case of good synergy between surface and subsurface team in identifying and developing a debottlenecking effort of the geothermal surface facility to optimize reservoir management system and to meet the operation target in sustaining generation. • Minimizing pressure drop in geothermal production line can provide economical benefits to the company by deferring make up wells drilling and extending steam supply plateau • In response to changes in reservoir condition and operation mode, the improvement effort must be done as an integration process between Resource Management, Facility Engineering, and Operation and Maintenance. Best Practices Adopted and to Share:* List key best practices that you would like to share with others regarding this abstract. Maximum 500 characters. • An integrated multidisciplinary effort to identify and implement geothermal production system optimization. |