Abstract

Preformed stable foam is a proven process that has an extensive successful Preformed stable foam is a proven process that has an extensive successful track record. This paper emphasizes its use in several applications in low pressure reservoirs, such as: Sand cleanout, recompletion, new completions, pressure reservoirs, such as: Sand cleanout, recompletion, new completions, and concentric tubing work.

New applications for stable foam; namely, gravel packing and balanced-pressure caring far insitu formation saturation, are discussed.

The use and importance of a foam circulation computer model is illustrated. This model has proven to be extremely accurate and valuable as a planning tool in establishing the liquid/volume ratio and annular back pressure requirements for balanced pressure operations.

Case histories and survey results are presented to illustrate the cost savings and production benefits of foam circulation.

Introduction

The preformed stable foam process development was started by Chevron U.S.A., Inc. several years ago to solve the problem of extreme loss of drilling fluid in the underpressured pay zones of shallow wells in the San Joaquin Valley of California. Since that time, the process has been improved, modified and adapted to many uses. Over 17 patents have been issued covering various uses of preformed stable foam. Licenses have been issued to over 35 service companies around the world to make the process available to Chevron and other operating companies. To date, over 35,000 foam lobs have been performed.

Numerous papers have been published reporting on the use of preformed stable foam for drilling large diameter holes, drilling lost circulation intervals, speeding penetration rate, drilling permafrost and washing perforations. perforations. This paper will address the use of preformed stable foam in the completion interval of underpressured reservoirs.

PREFORMED STABLE FOAM PROCESS PREFORMED STABLE FOAM PROCESS The preforming of the foam on the surface is of critical importance. We have found experimentally and in the field that preformed foams can withstand much more contamination from crude oil, salt waters, and salts than foams formed in the presence of these materials.

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