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US 12,241,016 B2Granted
High temperature high salt low end rheology modifiers
AssigneesCNPC USA Corporation, Beijing Huamei, Inc., China National Petroleum Corporation
InventorsJanine Shipman, Meng Lu, Weibin Zha
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Abstract
A low-end rheology modifier for adjusting rheological characteristics of water-based drilling fluid systems, particularly for high salt, high density drilling fluids in high temperature and high-pressure applications. The low end rheology modifier comprises a copolymer and laponite clay, the copolymer comprising tert-Butylacrylamidosulfonic acid (TBAS) and n-vinylpyrrolidone (NVP) crosslinked with N,N′-Methylenebis(acrylamide).
Claims11
A water-based drilling fluid, comprising:
- a low-end rheology modifier comprising laponite clay and a copolymer, wherein the laponite clay is present in the low-end rheology modifier in amounts of 50 mass % to 67 mass %, and wherein the copolymer comprises:
- a tert-Butylacrylamidosulfonic acid (TBAS) monomer;
- an n-vinylpyrrolidone (NVP) monomer;
- and
- a cross-linking monomer, wherein the cross-linking monomer is N,N′-Methylenebis(acrylamide),
- wherein the low-end rheology modifier is capable of increasing viscosity of the water-based drilling fluid at temperatures of above 450 degrees Fahrenheit.
3 more elements
Dependencies are inferred from the claim text.