Damaged Wellhead Rehabilitation of Well OK-5 Southern Negros Geothermal Production Field, Negros Oriental, Philippines

Abstract

Corrosion and silica deposition, aside from normal wear and tear, are the main causes of repair and replacement of major equipment in the geothermal plantÆs fluid collection and disposal system (FCDS) like pipelines, valves, and other accessories. In the Philippines, most geothermal fields are located in mountainous, rugged terrain and coupled with the regular visits of typhoons bringing with it heavy precipitation create favorable conditions for landslides. A major landslide with an estimated volume of 50,000 cubic meters occurred on October 23, 1998 that hit the Wells OK 5 and BL 2D in Palinpinon I production field. The debris devastated the wells and its pipelines. The wellhead tee of Well OK 5 was sheared-off above the master valve and the well discharged at fullbore to the atmosphere. The task of the wellhead rehabilitation faced a number of physical obstacles. But the true challenge was on ôtaming the wild wellö so that repair of the sheared-off tee, the cracked anchor casing, and replacement of the master valve could follow. Teamwork and the years of experience contributed to the success of the well rehabilitation. The rehabilitation took 6 ? months and Php 30 million charged to insurance.