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 declined after more than 20 years of continuous exploitation. Pressure drawdown combined with effects of injection returns has been the major reservoir process affecting steam production. The formation of mineral deposits within the wellbore further aggravated the problem. By early 2004, the steam supply can only support a maximum plant load of about 105 MW. To curb the declining trend, brine injection was shifted further away from the production sector and mechanical workovers were conducted. While mechanical workover alone had been successful in clearing mineral deposits within the wellbore, it is not capable in removing those that are in the formation. The inclusion of acid stimulation in conjunction with this workover has been proven effective in cleaning out 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 workover/acidizing jobs in both production and 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.