Method for removing filtercake
AssigneeTetra Technologies, Inc.
InventorsJoseph R. Murphey, Jeffrey S. McKennis, Keith W. Sharp
Life of this patent
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Abstract
A method for removing filtercake from a subterranean borehole comprising drilling the borehole with a drilling fluid that includes additives to form a filtercake having an oxidation-degradable component, preferably a polysaccharide. The filtercake is contacted with a clear brine containing bromine or bromate generating agents to degrade the polymers within the filtercake. The brine contains bromide salts and an oxidant capable of delayed oxidation of the bromide to bromine at downhole conditions.
Claims20
A method for preparing a borehole in the earth to produce hydrocarbons therefrom, comprising:
- drilling the borehole while circulating a mud therein which comprises a polysaccharide and optionally comprises finely divided solids dispersed therein to form a filtercake on surfaces of the borehole essentially free of oxidants and bromine and bromate generating agents;
- and
- introducing a filtercake removal fluid in the wellbore, in contact with a subterranean formation containing the hydrocarbons to be produced, for a duration effective to substantially remove the filtercake in the vicinity of the subterranean formation, wherein the filtercake removal fluid comprises a clear brine comprising a halide salt having a density of at least 1.08 g/cm.sup.3 (9 lb/gal) and a bromine or bromate generating agent dissolved in the brine.
A method for preparing a borehole in the earth to produce hydrocarbons therefrom, comprising:
- drilling the borehole while circulating a mud therein which comprises a polysaccharide and optionally comprises finely divided solids dispersed therein to form a filtercake on surfaces of the borehole;
- thereafter installing gravel pack screens and tool assemblies into the borehole;
- thereafter introducing sand in a nonviscosified carried into the borehole;
- and
- introducing a filtercake removal fluid in the wellbore, in contact with a subterranean formation containing the hydrocarbons to be produced, for a duration effective to substantially remove the filtercake in the vicinity of the subterranean formation, wherein the filtercake removal fluid comprises a clear brine comprising a halide salt having a density of at least 1.08 g/cm.sup.3 (9 lb/gal) and a bromine or bromate generating agent dispersed in the brine.
A filtercake removal fluid for cleaning a borehole drilled in the earth, comprising:
- a clear brine comprising a bromide salt of a metal selected from alkali metals, alkaline earth metals, transition metals and combinations thereof, having a density of at least 1.08 g/cm.sup.3 (9 lb/gal), a pH from about 3 to about 7, and essentially free of iron;
- an oxidant dissolved in the brine in an amount effective for oxidation of the bromide to bromine at an elevated temperature between 40.degree. C. and 120.degree. C., wherein the oxidant is stable to essentially avoid free bromine formation at ambient temperatures.
Dependencies are inferred from the claim text.