Sustaining Steam Supply in Palinpinon 1 Production Field Southern Negros Geothermal Project, Philippines

Abstract

Steam supply to the 112.5 MWe power plant in Palinpinon 1 has gradually declined after more than 20 years of continuous exploitation. Pressure drawdown combined with effects of re-injection returns has been the major reservoir processes affecting steam production. The formation of mineral deposits within the wellbore further aggravated the problem. Presently (May 2004), the steam supply can only support a maximum plant load of about 102 MW. To curb the declining steam supply, brine injection was shifted further away from the production sector and mechanical work-overs were conducted. While mechanical work-over alone had been successful in clearing mineral deposits within the wellbore, it is not capable in removing those at are deposited in the formation. The inclusion of acid stimulation in conjunction with this work-over has been proven effective in clearing mineral deposits within the wellbore as well as in the immediate formation of the open hole thus, significantly increasing the chances of restoring the original output of the well.

This paper presents the results of the recent work-over/acidizing jobs in both production and re-injection wells in Palinpinon 1 and discusses some of the requisites and procedures in conducting an acid stimulation job vis-?-vis the wellbore characteristics of the well.