FEASIBILITY STUDY OF NON-PRODUCTIVE WELL UTILIZATION IN GEOTHERMAL BY USING MULTIPHASE PUMP–CASE STUDY OF ULUBELU GEOTHERMAL AREA)

• Main Author: ALFANDI AHMAD (NIM: 22615302), ANGGA
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/25574
• Institution: Institut Teknologi Bandung

<p align="justify">The production rate of geothermal wells is decreasing over time, so the amount of steam supply to the Geothermal Power Plants (GPPs) is also decreasing. Generally, to maintain the production, drilling make-up wells should be conducted. On the other hand, there are non-productive wells in the geothermal field that incapable to deliver steam to the GPPs due to their wellhead pressure (WHP) are relatively low. It is interesting to study this topic because the non-productive wells are still potentially producing the steam that can be used to be an additional steam supply to the GPPs. By using a Multiphase Pump (MPP) which capable of operating at various fluid phase conditions (0-100% dryness), the pressure of non-productive wells will be increased, so it will be able to deliver the steam to the GPPs. The MPP type that used in this research is twin-screw multiphase pump. The aim of this research is to study the feasibility of implementing the MPP in the non-productive wells thermo-economically. As a case study, this research is using UBL-C as one of the non-productive well in the Ulubelu Geothermal Field. <br /> <br /> <br /> <br /> Based on WELLSIM simulation result at the maximum opening of the wellhead valve (5.7 bars), UBL-C could produce a total mass flow rate of 235.7 tph with the enthalpy of 1065 kJ/kg, and 16% fluid dryness. The decline rate of this well was assumed to be 7%. In order to deliver the geofluid to GPPs, the pressure of UBL-C needs to be increased up to 10 bars (the pressure at production header pipe) by using MPP. The electric power required for MPP varies from 754–1005 kWe at 60–80% MPP efficiency, while the generated gross power of the UBL-C was 5.45 MWe. The economic calculation of MPP implementation for 15 years yields positive NPV value with range from $4.6 to $5.3 million at 60% to 80% MPP efficiency, with IRRs was ranging from 24.6% to 26.2%. This would make the pay out time (POT) in the 4th year after MPP was implemented. The comparison analysis result between MPP implementation and the drilling of a new well concluded that MPP was more feasible and profitable to be implemented in UBL-C techno-economically. In addition, this MPP implementation might delay the make-up wells drilling schedule for one year.<p align="justify">