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US 12,428,588 B2Granted
Synergistic viscosifiers for clay-free, water-based drilling fluids
AssigneeHalliburton Energy Services, Inc.
InventorsEmily Hart, Hui Zhou, William W Shumway
Life of this patent
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Abstract
A water-based drilling fluid can include a first and second viscosifier of a cross-linked starch and a cross-linked acrylamide-based polymer. The acrylamide-based polymer can be crosslinked and optionally include hydrophobic monomers. The viscosifiers create a synergistic effect that imparts desirable properties to the drilling fluid compared to using either of the viscosifiers alone. The viscosifiers can be used as an alternative to other types of viscosifiers such as xanthan gum.
Claims19
A drilling fluid comprising:
- a base fluid comprising water;
- a first viscosifier consisting of a pre-cross-linked starch;
- and
- a second viscosifier consisting of a pre-cross-linked acrylamide-based polymer,
- wherein the first viscosifier and the second viscosifier create a synergistic effect whereby a first test drilling fluid consisting of the base fluid, the first viscosifier, and the second viscosifier in the same concentrations as the drilling fluid has a yield point in the range of 17 to 30 lb/100 ft2 (7.2 to 14.4 Pa) and a 10-minute gel strength greater than or equal to 8 lb/100 ft2 after hot rolling compared to a second test drilling fluid consisting of the base fluid and only the first viscosifier or the second viscosifier in a concentration equal to both the first and second viscosifier in the first test drilling fluid that has a yield point less than or equal to 17 lb/100 ft2 (7.2 Pa) and a 10-minute gel strength less than 8 lb/100 ft2 after hot rolling,
- wherein the drilling fluid does not comprise a clay, and
- wherein the drilling fluid is pumpable.
4 more elements
A method of drilling a wellbore in a subterranean formation comprising:
- introducing a drilling fluid into the subterranean formation, wherein the drilling fluid comprises:
- a base fluid comprising water;
- a first viscosifier consisting of a cross-linked starch;
- and
- a second viscosifier consisting of a cross-linked acrylamide-based polymer,
- wherein the first viscosifier and the second viscosifier are cross-linked prior to introduction of the drilling fluid into the subterranean formation,
- wherein the first viscosifier and the second viscosifier create a synergistic effect whereby a first test drilling fluid consisting of the base fluid, the first viscosifier, and the second viscosifier in the same concentrations as the drilling fluid has a yield point in the range of 17 to 30 lb/100 ft2 (7.2 to 14.4 Pa) and a 10-minute gel strength greater than or equal to 8 lb/100 ft2 after hot rolling compared to a second test drilling fluid consisting of the base fluid and only the first viscosifier or the second viscosifier in a concentration equal to both the first and second viscosifier in the first test drilling fluid that has a yield point less than or equal to 17 lb/100 ft2 (7.2 Pa) and a 10-minute gel strength less than 8 lb/100 ft2 after hot rolling,
- wherein the drilling fluid does not comprise a clay.
5 more elements
Dependencies are inferred from the claim text.