Schlumberger Technology Corporation

Bruno Goffe

Véronique Barlet-Gouedard

Erik B Nelson

Samuel Danican

Chrystel Cambus

In a process to design high temperature cement sluries, the temperature stable phases (anorthite, wairakite) are selected; aluminum modifiers and silica oxides are added to the dry cement so that the elemental composition of the blend corresponds to the phases selected; the control of the particle size distribution and the relative amount of those minerals allow their addition at high concentration while leaving the slurry easily mixable and pumpable; and the kinetics of the targeted phases formation is then controlled by adjusting the crystallinity and the particles sizes of the different solids.

Cement compositions for high temperature applications

A method of designing a cement composition comprises determination of the temperature to which the composition will be exposed in situ; determination of a stable, thermodynamic equilibrium composition of a CaO&#x2014;AlO&#x2014;SiO&#x2014;HO (CASH) mineral system in the [xonotlite/wollastonite]-grossulaire-anorthite or grossulaire-anorthite-quartz triangles of the Si&#x2014;Ca&#x2014;Al phase diagram with a possible contribution of iron and/or magnesium, analogous to the cement when set, at the determined temperature; determining proportions of cement and mineral oxides required to provide a mixture having the determined composition; and defining a series of particulate materials of predetermined particle sizes and densities, comprising cement and mineral oxides in the determined proportions.

High temperature cements

The present invention concerns cementing compositions for an oil well or the like, based on a Portland cement, silica and alumina, wherein the mineralogical composition of the cement matrix is included in the Si&#x2014;Ca&#x2014;Al triangle in one of the margarite-ha&#xfc;yne-[epidote/pumpellyite], ha&#xfc;yne-prehnite-[epidote/pumpellyite] and ha&#xfc;yne-prehnite-pectolite composition triangles. More particularly, the cementing compositions of the invention are suitable for cementing wells subjected to high temperatures and to chemical attack by brines, and are more suitable when the brine&#x2014;or a saline formulation close to that of the brine&#x2014;is used as the mixing water.

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Paris, France

Bruno Goffe