Compositions and methods for cleaning subterranean boreholes
AssigneeSchlumberger Technology Corporation
InventorsStephane Boulard, Jesse C. Lee
Life of this patent
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Abstract
Lipophilic fibers are effective media for cleaning non-aqueous fluids out of a subterranean wellbore. The fibers are preferably added to a drilling fluid, a spacer fluid, a chemical wash, a cement slurry or combinations thereof. Non-aqueous fluids, such as an oil-base mud or a water-in-oil emulsion mud, are attracted to the fibers as they circulate in the wellbore.
Claims11
A method for cleaning a borehole in a subterranean well whose surfaces are coated with a non-aqueous fluid and are initially oil wet, comprising:
- (i) providing an aqueous treatment fluid comprising lipophilic fibers coated by a hydrophilic sizing to promote dispersion in the aqueous treatment fluid;
- (ii) circulating the treatment fluid in the borehole;
- and
- (iii) removing the treatment fluid from the borehole;
- wherein, the non-aqueous fluid is removed from the well and the borehole surfaces are rendered water wet;
- wherein the fibers contact the non-aqueous fluid, absorb 10 to 60 times their weight of the non-aqueous fluid and have a solid surface energy between 20 mN/m and 40 mN/m,
- wherein the hydrophilic sizing comprises starch, xanthan polymers, guar, guar derivatives, carboxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, polyvinyl alcohols, or water-soluble acrylates or combinations thereof.
A method for cementing a subterranean well having a borehole whose surfaces are initially oil wet, comprising:
- (i) providing an aqueous treatment fluid comprising lipophilic fibers coated by a hydrophilic sizing to promote dispersion in the aqueous treatment fluid;
- (ii) circulating the treatment fluid in the borehole;
- (iii) removing the treatment fluid from the borehole, wherein, non-aqueous fluid is removed from the well and borehole surfaces are rendered water wet;
- (iv) providing a cement slurry;
- and
- (v) placing the slurry in the well;
- wherein the fibers contact the non-aqueous fluid, absorb 10 to 60 times their weight of the non-aqueous fluid and have a solid surface energy between 20 mN/m and 40 mN/m,
- wherein the hydrophilic sizing comprises starch, xanthan polymers, guar, guar derivatives, carboxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, polyvinyl alcohols, or water-soluble acrylates or combinations thereof.
A method of treating a well having a borehole, the borehole drilled with oil based mud or synthetic based mud, whose surfaces are initially oil wet, the method comprising:
- (i) providing an aqueous treatment fluid comprising lipophilic fibers coated by a hydrophilic sizing to promote dispersion in the aqueous treatment fluid;
- (ii) circulating the treatment fluid in the borehole;
- and
- (iii) removing the treatment fluid from the borehole;
- wherein, non-aqueous fluid is removed from the well and borehole surfaces are rendered water wet;
- wherein the fibers contact the non-aqueous fluid, absorb 10 to 60 times their weight of the non-aqueous fluid and have a solid surface energy between 20 mN/m and 40 mN/m,
- wherein the hydrophilic sizing comprises starch, xanthan polymers, guar, guar derivatives, carboxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, polyvinyl alcohols, or water-soluble acrylates or combinations thereof.
Dependencies are inferred from the claim text.