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Method of drilling with shale stabilizing mud system comprising polycyclicpolyetherpolyol

  • US 5,260,269 A
  • Filed: 03/19/1991
  • Issued: 11/09/1993
  • Est. Priority Date: 10/12/1989
  • Status: Expired due to Term
First Claim
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1. A method for enhancing the effectiveness of a calcium base drilling fluid to reduce cuttings dispersion and increase wellbore stability during the drilling of an oil or gas well, comprising:

  • providing the components of a drilling fluid comprising solids, a fluid comprising water and a calcium compound in a concentration of from about 1 to 15 pounds per barrel of the fluid, said calcium compound being selected from the group consisting of lime, gypsum and mixtures thereof;

    enhancing the effectiveness of the drilling fluid by admixing the drilling fluid components with (a) salt in a concentration of about 5 to 40% by weight of the fluid, said salt being selected from the group consisting of NaCl, NaBr, KCl, CaCl2, NaNO3, NaC2 H3 O2, KCHO2 and mixtures thereof, and (b) an alcohol in a concentration of from about 2 to 30% by weight of the fluid, said alcohol being a polycyclicpolyetherpolyol having a molecular weight Mw in excess of 50,000; and

    reducing cuttings dispersion and increasing wellbore stability by drilling the wellbore with the enhanced calcium base drilling fluid and circulating the drilling fluid in the wellbore.

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