Steam Supply Sharing Through Steamline Interconnection - The Tongonan Geothermal Field Experience, Philippines

Abstract

Since the commissioning of the new power plants in the Philippine National Oil Co. - Energy Development Corporation (PNOC-EDC) operated Tongonan Geothermal Field and its adjacent Mahanagdong Geothermal Sector in Leyte Philippines in 1996 under the Build-Operate-Transfer (BOT) scheme, there have been a number of reservoir management strategies formulated and implemented to ensure continuous supply of the required steam to the installed power plants. One of these field management strategies is the construction of a cross-country steamline interconnection called the "steam-highway" which links the different sectors of the Greater Tongonan Geothermal Field. The steam highway pipeline network interconnects all three major sectors of the Tongonan Geothermal Field, namely the Tongonan 1, Upper Mahiao and Malitbog-South Sambaloran, with the adjacent Mahanagdong Field.

This inter-sectoral / field linkage, commissioned in year 2000, provides flexibility in the operation of the field by allowing delivery of excess steam from the Upper Mahiao, Tongonan 1, Malitbog-South Sambaloran up to the Mahanagdong sector to ensure optimized power generation from the BOT plants.

Historical and present distribution of the excess steam is discussed and the reservoir response of the supplying sectors / field as a result of this scheme were reviewed. Reservoir trends since the commissioning of the steamline interconnection have indicated that the Upper Mahiao and Tongonan 1, the main supplying sectors, can sustain additional extraction for the supply of steam to the recipient sectors.