Design and Construction of the Kawerau Steam Field

Abstract

The steam field design and construction at the MRP Kawerau Geothermal Project in New Zealand is unique in many ways. The location of one well pad is unusual in that it is in the middle of an industrial complex. The steam field two-phase piping system runs uphill, downhill and under culverts, which is against the recommended practice. The Steam field has 11 culvert crossings under access roads. It crosses a major state highway twice; once using a bridge and a second time using a long tunnel. It also runs through a railway yard. A single pipe carrying 67% of the two-phase fluid runs through the industrial complex occupied by multiple owners. The construction access inside this industrial complex was restricted and the pipeline was built over known and unknown services installed over the last 50 years. This pipe line had to be routed to avoid damaging trees and to squeeze through narrow corridors inside the industrial complex and the main access road to it. The other 33% of this two-phase fluid also flowing inside a single pipe crosses mostly farm land, rises up on a bridge to cross the state highway and runs through a log yard area.
During construction, the underground services in the plant were located using ground penetrating radar and hand digging. The pipeline route was altered in several places and some of the pipe supports were redesigned to avoid the rising water table and unknown underground obstacles.
The steam field was successfully completed on time without damage to any services and minimal damage to trees.