Specialized Technique - Foam Cementing

Location: Philippines

Project Overview:

Foamed cement is a mixture of cement slurry, foaming agents, and a gas (nitrogen). The bubbles formed are not interconnected, which results in a low-density cement matrix with low permeability and relatively high strength compared to conventional cements. Because of these properties, foam cement can help to prevent lost circulation and seal-off lost circulation zones. The loss of fluid circulation while drilling is arguably the most costly and unpredictable problem in geothermal drilling. The foam cementing technique, pioneered by Bill Rickard in geothermal drilling, enables successful cementing of wells in highly permeable reservoirs and easily-fractured zones. The use of foamed cement also eliminates the need for tie-back strings and a two-stage cement jobs to bring cement returns to the surface, allowing the operator to save on valuable rig time.

Foamed cement also has unique pseudo-plastic properties not seen in conventional cements, making it resistant to both temperature and pressure-induced stresses that can cause conventional cements to fail. Because of the high fluid and formation temperatures encountered in geothermal wells, the proper use of foamed cement can help to ensure the cement sheaths integrity needed to be preserved over the life of the well.