Restoring lost circulation
AssigneeShell Oil Company
InventorsM. Kenneth Cowan, Arthur H. Hale
Life of this patent
Estimating the term…
Abstract
Method for restoring drilling fluid circulation to a borehole having strata being invaded by the drilling fluid, by circulating a non-conventional cementitious slurry such as drilling fluid-blast furnace slag mixture into the strata, and allowing the mixture to solidify in situ.
Claims12
A method for restoring drilling fluid circulation to a borehole of a well having surrounding strata being invaded by the drilling fluid which is thereby escaping the borehole, comprising:
- preparing a cementitious slurry comprising:
- (a) a cementitious component selected from granulated water-quenched blast furnace slag and a proton acceptor metal compound and
- (b) an activator wherein, when said cementitious component is said blast furnace slag, said activator is optionally an alkaline agent, and when said cementitious component is said metal compound, said activator is a phosphorus acid or one of a polymer component of the formula:
- ##STR9## and wherein R is H or a 1-10 carbon atom alkyl radical and the ratio of m to n is within the range of 0:1 to 100:1;
- and
- (c) a water source selected from water, brine, seawater, water base drilling fluid, and water emulsion drilling fluid;
- displacing the cementitious slurry into the strata which the first said drilling fluid is invading, the cementitious slurry being in direct contact, during and after placement, with the drilling fluid in the borehole;
- and
- allowing the cementitious slurry to solidify in situ to form a plug in the wellbore and thereby sealing the strata from the wellbore.
A method for restoring drilling fluid circulation to a borehole of a well having surrounding strata being invaded by the drilling fluid which is thereby escaping the borehole, comprising:
- preparing a cementitious slurry comprising:
- granulated water-quenched blast furnace slag and a water source selected from the group consisting of water, brine, seawater, water base drilling fluid, and water emulsion drilling fluid;
- displacing the cementitious slurry into the strata which the first said drilling fluid is invading, the cementitious slurry being in direct contact, during and after placement, with the drilling fluid in the borehole;
- and
- allowing the cementitious slurry to solidify in situ to form a plug in the well bore and thereby seal the strata from the wellbore.
Dependencies are inferred from the claim text.