Revitalizing geothermal wells in the Philippines

Highly acidic, ultra-high temperature geothermal wells face an inherent challenge in that the production casing faces a high level of corrosion-and-cement-related risks, which if occurring, can compromise safety, efficiency, and performance.  

While a drillable bridge plug (BP) can be used to isolate problematic sections of a well, manage pressure, or perform temporary zonal isolation for repairs, this approach in itself also presents a risk in terms of potential damage occurring to the liner while chasing the BP to the bottom. 

In collaboration with Energy Development Corporation (EDC), the largest integrated geothermal company in the Philippines, Welltec® has developed and deployed a solution combining modified metal expandable packer (MEP) technology with cement port collar to rejuvenate sustainable, geothermal energy producers. 

Building on the success of previous deployments on behalf of EDC, this operation aimed to rejuvenate an eight-year-old geothermal production well.  

The solution features a 1214 Welltec Annular Barrier (WAB®) for geothermal applications, combined with a cementing system for improved annular seal over the remaining life of the well.

In geothermal well construction, the Welltec Annular Barrier (WAB) and a cement port collar work together to enhance well integrity and prevent any cement contamination during curing.  The WAB provides mechanical isolation by creating a robust seal in the annulus, while the cement port collar makes it possible to perform stage cementing thereby bonding the casing to the formation.  Their complementary roles ensure a dual barrier approach, with the WAB safeguarding against fluid migration and stress-induced casing damage, and the cement providing continuous sealing to withstand temperature fluctuations, thus delivering a comprehensive solution for challenging geothermal conditions.  A bespoke valve block configuration was also incorporated into the design of the WAB to eliminate the risk of trapped fluid and/or annular pressure buildup that may cause premature failure.

Several operational meetings and well diagnostics were conducted in order to overcome various challenges related to deployment and the hostile downhole conditions, confirming setting pressure, space-outs, piston forces acting on the cement port collar sleeve, all in collaboration with the client.

The project marked a significant achievement in the design and deployment of a bespoke solution that enabled the relining and cementing of the casing without requiring a drill-out run, while also preventing trapped fluid that could compromise the new relined casings.

The cement was confirmed to have reached the surface, verifying a successful top of cement (TOC), and the well was successfully relined. 

The deployment of the WAB solution has now set the benchmark for relining highly acidic, low pH wells for EDC.  Welltec provided a comprehensive, fit-for-purpose solution to address various well issues, and any safety concerns arising from collapsed and parted casing in the shallow section.