Geothermal drilling is more expensive (in cost/depth) than onshore oil and gas drilling for three principal reasons:
- Technical Challenge: The conditions associated with geothermal operations mean that special tools and techniques are required for the harsh downhole environment.
- Large Diameters: Because the produced fluid (hot water or steam) is of intrinsically low value, high flow rates and large holes and casing are required. In many cases, geothermal operations also require more casing strings to achieve a given depth in a geothermal well than in an oil well to the same depth.
- Uniqueness: Geothermal wells, even in the same field, are different than oil and gas wells, so the learning curve from experience is less useful.
Because of these factors, fit-for-purpose and reliable technology is required in order to develop geothermal wells.
- Ultra-high temperatures – Ultra-high temperature is a primary characteristic of geothermal wells. Equipment designs must take into account the fact that as the temperature goes up, the strength of the materials goes down.
- Derating of pressure vessels – Degradation of metals resulting from harsh well environments causes pressure ratings to be reduced.
- Dynamic sealing requirements – Production casing thermally expands upward as the well is brought online and will retract downward as the well is shut in. These conditions must be accommodated by the seals of the pack-off assembly in the bottom of the expansion spool.
- Scale buildup inside equipment – Scaling is another characteristic of geothermal service that requires attention. Once a well has been flowing and is subsequently shut in, a large amount of scale tends to build up in stagnant crevasses. A 1” scale buildup in a valve bore is not uncommon.
- Equipment maintenance and failures – Scale buildup, erosion, and corrosion create opportunity for equipment failures and poses maintenance difficulties.
Cameron’s WKM® and FOSTER® solutions provide total fluid control for virtually any type of geothermal reservoir, including vapor dominated, liquid dominated, dry hot rock, and geopressure. No matter where in the world, we can provide a geothermal system to meet your needs. In addition, our systems can be used on thermally enhanced (steam injection) recovery, waste disposal, and hot water wells.
Our engineering design and manufacturing standards have been specifically developed for geothermal well applications, providing quality guidance for wellhead and gate valve equipment. This design standard helps ensure completeness and consistency of design across all of Cameron's facilities and helps meet applicable specifications of Cameron, the industry, and the operator. Our quality requirements necessitate evaluation of critical performance characteristics for components and assemblies.
Cameron's geothermal wellhead and valve offerings increase confidence in flow control integrity on your sustainable energy wells. We offer a full range of proprietary geothermal elastomers developed and manufactured exclusively by Cameron. All of our products are backed by our worldwide network of sales, service, and aftermarket facilities. We also provide a variety of drilling products, including BOPs and gate valves.