US 12,241,016 B2
High temperature high salt low end rheology modifiers
Janine Shipman, Houston, TX (US); Meng Lu, Sugar Land, TX (US); and Weibin Zha, Spring, TX (US)
Assigned to CNPC USA Corporation, Houston, TX (US); Beijing Huamei, Inc., Beijing (CN); and China National Petroleum Corporation, Beijing (CN)
Filed by CNPC USA CORPORATION, Houston, TX (US); Beijing Huamei Inc., Beijing (CN); and CHINA NATIONAL PETROLEUM CORPORATION, Beijing (CN)
Filed on Aug. 8, 2022, as Appl. No. 17/818,155.
Prior Publication US 2024/0043734 A1, Feb. 8, 2024
Int. Cl. C09K 8/24 (2006.01); C09K 8/14 (2006.01)
CPC C09K 8/24 (2013.01) [C09K 8/145 (2013.01)] 11 Claims
 
1. 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.