Welltec, the Denmark headquartered oil service provider, says that the cleaning tools it manufactures have proven highly successful during testing for something other than oil wells: geothermal well cleaning applications.
The Well Miller® has capabilities for:
– Silica removal – a common cause of geothermal production issues
– Rigless intervention
– Minimal footprint – lightweight yet high capacity tools
– Saving time and money through fast
The Well Miller Reverse Circulating Bit (RCB) is a combinable milling tool enabling the simultaneous milling, break-up, and extraction of scale. The RCB also features a turbine section allowing well fluid to be circulated through the milling bit, and for any cuttings or debris to be collected into bailer chambers for later recovery once tools are rigged down at surface.
In testing, the RCB was run against a cured blend of silica pieces (Si02), sand, and epoxy resin, to replicate the most challenging silica clean-out scenario found in a geothermal setting.
“Not only was the removal of the silica replicant compound successful, the mill bit showed almost no signs of wear, thanks to highly resistant Tungsten Carbide milling teeth”, Welltec reports I a case study.
Overcoming Challenges
Welltec says it is already helping clients with geothermal well construction by providing the Welltec Annular Barrier (WAB®) for zonal isolation – a life of well solution.
“In terms of maintenance and intervention, Silica scale is one of the main flow production issues found in Geothermal wells. In particular, the challenge faced with this type of material stems from its strength and high level of resistance, making it incredibly difficult to mill through”, the company explains.
Geothermal Potential
Welltec believes that Geothermal energy offers the highest capacity energy form within the renewables market. ”With the ongoing development of Enhanced Geothermal Systems (EGS), the future potential is further expanded and can help to facilitate an even more efficient and sustainable way to harness the Earth’s natural energy source,” the company declares on its website.
Collaboration in the Field
Welltec continues to collaborate with industry experts and provide technology for research projects with allocated funding from the U.S. Department of Energy. In a project led by the University of Oklahoma and Veizades & Associates, Welltec will be testing its latest Welltec Annular Barrier (WAB) in multiple zones of interest at the Coso Geothermal Field, California.The WAB will be applied to achieve zonal isolation and improve mass flow through stimulation in a high temperature environment.
Academic contribution
Welltec has recently co-authored an academic paper with Energy Development Corporation (EDC) of the Philippines, presenting highly successful well repair operations from the field. The paper highlights the benefits of repairing wells to re-establish production rather than abandoning them for new ones– in doing so, the WAB can prevent casing collapse and deformation caused by trapped water.
The case will be presented at the 42nd New Zealand Geothermal Workshop on 24-26 November, 2020.
