Schlumberger Technology Corporation

Andre Garnier

Jack Maberry

Greg Garrison

Pierre Maroy

Slaheddine Kefi

Bernard Dargaud

Veronique Barlet-Gouedard

Stephan Harris

Anne-Marie Schulz

The present invention provides improved well cementing methods for use in cold environment, where the circulating temperature of the cement is typically within the range of 5 to 20&#xb0; C. The improved well cementing methods include forming compositions that are essentially comprised of an aqueous fluid, a hydraulic cement binder and a set-accelerating admixture comprising an alkali or alkaline earth metal nitrate and an alkali or alkaline earth metal nitrite.

Process of well cementing in cold environment

Method of well cementing with a foamed slurry having a very low water content. When based on ordinary cement, the solid fraction of the slurry includes (by volume) 20-35% Portland cement, 35-65% particles ranging from 200 &#x3bc;m to 600 &#x3bc;m, and 5% to 25% of fine particles in the range 0.5 &#x3bc;m to 5 &#x3bc;m and the water content is less than 50% by volume. When based on micro-cement, the solid fraction includes (by volume) 50-75% micro-cement, 15-40% fine particles in the range 0.5 &#x3bc;m to 5 &#x3bc;m, and 0-20% particles in the rang 3 nanometers to 60 nanometers and the water content is less than 72% by volume.

Cementing compositions and application of such compositions to cementing oil wells or the like

A plugging fluid for plugging a subterranean formation zone surrounding a drill hole comprises an emulsion comprising a dispersed aqueous phase containing an aqueous base and a continuous hydrophobic phase containing a polymer consisting of a grafted cellulose ether derivative, a surfactant and a crosslinking activator of the polymer. The polymer is preferably 2-hydroxyethyl cellulose grafted with vinyl phosphonic acid. Upon shearing, preferably through the drilling bit, the emulsion inverts so that the rupture of the emulsion droplets releases the crosslinking activator into the water phase thus forming a gel structure.

Shear-sensitive plugging fluid for plugging and a method for plugging a subterranean formation zone

The invention concerns cementing compositions, particularly for squeeze cementing, comprising a liquid phase and a solid phase constituted by particulate materials which are insoluble in said liquid phase, in particular a microcement. The compositions of the invention comprise additives of a nature and composition such that variations in viscosity of the composition due to fluid loss are minimized. Preferably, the compositions comprise at least one &ldquo;very fine&rdquo; additive formed from particles which are smaller than the cement, with a ratio of the average grain sizes of the particles of said additive and those of the cement in the range 5 to 100, preferably about 10, the respective proportions of the solid particles corresponding to a packing volume fraction close to the maximum, and the porosity of the solid mixture being such that the mixture is in a state of hindered settling.

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Katy, TX, United States of America

Andre Garnier