Schlumberger Technology Corporation

Dowell, a Division of Schlumberger Technology Corporation

Jean-Francois Baret

John Villar

Joel Rondeau

Michel Michaux

Pierre Maroy

Bernard Dargaud

Bernard Andre Montaron

The invention relates to a method and to a tool for treating at least one wall in a critical zone of a borehole, in particular a borehole for development of a hydrocarbon, water, gas or analogous field, the method consisting in reinforcing the wall of the critical zone by a coating obtained from a base fluid which is pumped from the surface to a tool ( ) to be projected against the wall of the critical zone where it forms the coating once it has set, the method being characterized in that it consists in storing at least one additive or activator in liquid form in a reservoir (R) of the tool ( ), and in projecting the additive simultaneously with the base fluid against the wall of the critical zone via at least one injector (I) in order to activate setting of the base fluid.

Method and a tool for treating the wall of a critical zone in a borehole

The present invention provides a cementing composition for an oil or analogous well, essentially constituted by a solid fraction suspended in a liquid medium. The solid fraction is constituted by a coarse fraction with a packing volume fraction .PHI..sub.1 which, according to the invention, is maximised, and a fines fraction x with a packing volume fraction .PHI..sub.2 which is less than or equal to the volume fraction x.sub.0 such that ##EQU1## The invention also provides a method of maximising the value of .PHI..sub.1. The invention can minimise fluid loss whatever the materials selected for a cementing composition.

Cementing slurry and method of designing a formulation

The present invention concerns a cementing composition for an oil (or similar) well, based on an aluminous hydraulic cement, fine particles, hollow microspheres, water in a quantity such that the porosity is in the range 25% to 50%, a dispersing agent, a setting accelerator for the aluminous cement and optionally, other conventional additives. The invention is of particular application to cementing conductor pipes in arctic zones or in deep-water wells.

Cementing compositions and applications of such compositions to

The particulate phase of fluids according to the present invention comprises particles which have specifically adapted size ranges or granulometries. All the essential properties of fluids and their cost are very clearly improved. The technique may be applied to all well operations in oil wells or the like, such as in matrix treatment and the like.

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Paris, France

Jean-Francois Baret