Schlumberger Technology Corporation

Frederik Nilsson

Pierre Maroy

Sylwia Komocki

V&eacute;ronique Barlet-Gouedard

Fabien J Brand

Benedicte Zusatz

A cement system for use in treating lost circulation includes a slurry of cement, water and a super-absorbent polymer which absorbs free water in the slurry to form a gel&#x2014;ore preferably a solid-like structure&#x2014;when placed in the well, and which releases the absorbed water to the cement hydration reaction as the cement sets. The absorption of water causes the slurry to develop a solid-like structure. In one embodiment, the superabsorbent is polyacrylamide or modified crosslinked poly(meth)acrylate. Also presented is a method of treating lost circulation by pumping the above-mentioned cement system.

Compositions and methods for treating lost circulation

A surfactant composition for use in well treatment, particularly for removing oil-based mud deposits from a well prior to cementing, comprises an alkylpolyglucoside in a solution of a mutual solvent for water and hydrocarbon. The composition can be used to formulate a chemical wash by dissolving the composition at a concentration of about 1%-10% (e.g. 5%) by weight in water or brine.

Surfactant compositions for well cleaning

Systems for retarding setting in an oilfield well cement slurry comprise a solution of a phosphonate selected from methylene phosphonic acid derivatives and a phosphate, in particular selected from the following salts or the corresponding acids: mono-phosphates (ortho-phosphates PO ; meta-phosphates PO ), acyclic poly-phosphates (pyrophosphates P O , tripolyphosphates P O ) or cyclic poly-phosphates. The system preferably may also comprise a retarder booster and is more particularly applicable to cementing at low or medium temperatures.

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Paris, France

Frederik Nilsson