Schlumberger Technology Corporation

Nikhil Shindgikar

Jesse Lee

Slaheddine Kefi

Michel Ermel

Chrystel Brunet-Cambus

Stephane Boulard

Chrystel Cambus-Brunet

Method for controlling lost circulation in a subterranean well using oil-dispersible lost-circulation materials which comprise fibers that are coated (or sized) with a lipophilic coupling agent, a lipophilic film-forming polymer or both. The fibers are preferably between about 6 mm and about 25 mm long, and between about 10 &#x3bc;m and about 200 &#x3bc;m in diameter. The fibers may be added to carrier fluids comprising oil-base fluids, synthetic-base fluids, invert-emulsion-base fluids and combinations thereof. The preferred fiber concentration in the carrier fluid is between about 0.55 g/L and about 28.5 g/L. The carrier fluid may be a drilling fluid, a spacer fluid or a lost-circulation pill.

Methods for controlling lost circulation in a subterranean well and materials there for

A composition, for use in treating oil wells, comprises fibers, hot melt adhesives and particulate solids. This composition has a wide range of applications including preventing or lessening lost circulation, wellbore strengthening or consolidation, controlling fluid loss, producing a 'stress cage' effect, gravel packing, acting as an aid to cementing, and for proppant backflow control.

Composition for borehole treatment

The following describes a novel and alternative mechanism in regards to releasing reactive chemicals. Namely, utilizing shells containing multiple emulsions that can be blended with the base fluids, and then react with said base fluid upon exposure to a trigger e.g. high shear and/or elongation flow, therefore plugging even large fractures. Such gelling lost circulation material allows to obtain a reliable carrier and fast reaction when triggered.

Well treatment

A composition made of fibers and a material able to exhibit reverse solubility has utility for treating subterranean wells. The composition may used to cure lost circulation. The composition may be added to drilling fluids, spacer fluids or cement slurries. As the fluid temperature increases in a well, the reverse solubility material may precipitate and migrate to the fibers, causing the fibers to stick to each other and form a network, thereby forming a barrier that reduces further egress of treatment fluid from the wellbore.

Method and composition for curing lost circulation

Mixtures of fibers and solid particles are effective for curing fluid losses and lost circulation in a subterranean well. Stiff fibers are more effective than flexible ones; however, mixtures of stiff and flexible fibers have a synergistic effect. The quantity and particle-size distribution of the solids are optimized according to the stiffness, dimensions and concentrations of fibers.

Engineered fibers for well treatments

An encapsulated thixotropy agent may be added to aqueous well service fluids. Such fluids include drilling fluids, cement slurries and polymer pills. The well service fluid may be subjected to shearing action downhole, causing the thixotropy agent to be released and imparting thixotropy to the fluid. The thixotropy agent comprises a dry suspension of synthetic layered silicates.

Method for providing thixotrophy to fluids downhole

A system for curing lost circulation is made of fibers and a material able to stick fibers in a network when activated. Such activation can be temperature or pH change or both. The fibers can be metallic amorphous fibers, metallic non-amorphous fibers, glass fibers, carbon fibers, polymeric fibers and combinations thereof. The material can be a fiber coating or an additional material, for example polyvinyl alcohol, polyurethane and heat activated epoxy resin.

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Paris, France

Nikhil Shindgikar