Comparison and selection of a steam gathering system in Ulubelu geothermal project, Sumatera, Indonesia

Abstract

This study focuses on the conceptual design of geothermal pipelines, especially for steam gathering systems. A tool for calculating a pipeline system was developed which emphasizes the comparison and selection of a pipeline system for transmitting geothermal fluids, with respect to optimal design and costs. Certainly it is related to the behaviour of fluid flow in a pipeline system. The calculation compares three different conceptual systems of geothermal fluid transmission: single-phase flow, two-phase flow and a combination of both systems (hybrid). It also compares fluid transmission using a single pipe and two parallel pipes. A case study is made of a steam gathering system for the Ulubelu geothermal project 2×55 MW, units 1 and 2, the high-temperature geothermal area under development in Indonesia by PT. Pertamina Geothermal Energy. The results show that the three studied systems give a similar design and costs for this project, but the hybrid system would be most efficient with regard to the characteristics of the existing project site. Generally, a single-pipe transmission is more economical than two parallel pipes. There was an insignificant difference in pipe diameter between the designs.