Foamed Cement — Solving Old Problems with a New Technique

TLDR

Foamed cement using nitrogen with intermediate‑weight slurry creates stable lightweight cement that overcomes limitations of conventional lightweight cements in oil‑field operations. The technique involves treating intermediate‑weight cement slurries with nitrogen to produce a hydrostatically balanced foam that can be applied with existing equipment, as demonstrated by laboratory data and field case histories. Successful foamed cement operations require specific safety measures, which are outlined in the study.

Abstract

ABSTRACT A new method of combining nitrogen with an intermediate-weight cement slurry (13 to 15 1 b/gal) to generate a stable foam has solved many of the problems associated with the use of conventional lightweight cements in oil-field operations. Foaming permits placing relatively high-strength, lightweight (6 to 11 lb/gal) cement slurries into the casing-formation annulus economically. Lightweight filler cement is often needed to provide a complete cement sheath along the length of the casing, where lost circulation is encountered or long lifts of cements are required. Various methods have been used in the past to obtain this lightweight slurry. These include the use of natural and chemical extenders, glass bubbles, ceramic bubbles and the combination of intermediate-weight cement slurries with gases. While the process of foaming cement to make lightweight slurries is not new, the technology for applying this process to oil and gas well cementing has been lacking. The new method requires special treatment and slurry design to obtain a hydrostatically balanced slurry along the entire length of the casing, but can be performed with current equipment and field personnel. Laboratory data and case histories have been used to describe these designs. The added safety requirements which must be in effect to successfully complete this type of cementing operation are discussed.