THE EVOLUTION OF STABLE FOAM AS A DRILLING MEDIUM

Abstract

In the late 1960s Stable Foam was developed by Chevron USA as a lightweight circulation medium to clean out production sand in depleted (depleting) wells. In employing this new medium they found that Stable Foam's compressible bubble structure provided up to 10 times the carrying capacity of many common liquid based circulating fluids.

These early successes led the industry to expand the use of Stable Foam from cased hole production clean outs to drill-ins, gravel packing, drilling in lost circulation zones, coil tubing, and today its utilisation as an Underbalanced Drilling fluid in depleted reservoirs.

Through this evolution Stable Foam has had its successes and failures as well as unique operational concerns which has affected its consideration and utilisation.

The following is a breakdown of the major hurdles which have been addressed and overcome, consequently positioning Stable Foam as a viable option for wider use in Underbalanced Drilling:

Foam compatibility in water, oil, salt and high temperature environments.MWD and Directional Drilling performance with a compressible fluid.Surface pressure control while drilling.

Surface separation and processing of a three phase well return fluid to provide a zero discharge closed loop circuit.