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OwnerJack C. Cowan, Michael J. Kilchrist +1inventors
InventorsJack C. Cowan, Michael J. Kilchrist, Robin J. Verret
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Disclosed is a method and gellable composition for decreasing the loss of fluid during well drilling or servicing operations. The gellable composition comprises a superabsorbent polymer in an acidic aqueous liquid in which the superabsorbent is not swellable. Preferably the gellable composition also contains a viscosifier, preferably chitosan. The method is practiced by forming the gellable composition, placing it at the location of fluid loss in a well, and mixing it with a basic aqueous liquid to raise the pH and thus allow the superabsorbent to expand in volume. Advantageously, the superabsorbent, chitosan, and an acid, preferably a solid acid, preferably sulfamic acid, are admixed to form an additive for preparing the gellable composition.
A method of decreasing the loss of fluid in a wellbore to a subterranean thief zone in which well drilling or servicing operations are being conducted which comprises preparing a gellable composition comprising an acidic aqueous liquid and a superabsorbent polymer swellable at alkaline pH, introducing the gellable composition into the thief zone by way of the wellbore, and contacting the gellable composition with an alkaline fluid in an amount sufficient to provide the gellable composition with an alkaline pH.
An additive for preparing a gellable composition to combat lost drilling fluid circulation in a subterranean thief zone which comprises a superabsorbent polymer chitosan, and an acid.
Dependencies are inferred from the claim text.