| US 7,514,389 B2 | ||
| High performance water-based drilling mud and method of use | ||
| Arvind D. Patel, Sugarland, Tex. (US); Emanuel Stamatakis, Houston, Tex. (US); and Steven Young, Cypress, Tex. (US) | ||
| Assigned to M-I L.L.C., Houston, Tex. (US) | ||
| Appl. No. 10/570,562 PCT Filed Sep. 01, 2004, PCT No. PCT/US2004/028330 § 371(c)(1), (2), (4) Date Nov. 15, 2006, PCT Pub. No. WO2005/023958, PCT Pub. Date Mar. 17, 2005. |
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| Application 10/570562 is a continuation of application No. 10/654505, filed on Sep. 03, 2003, granted, now 7,192,907. | ||
| Prior Publication US 2007/0082823 A1, Apr. 12, 2007 | ||
| This patent is subject to a terminal disclaimer. | ||
| Int. Cl. C09K 8/035 (2006.01); C09K 8/04 (2006.01) | ||
| U.S. Cl. 507—129 [507/222; 507/239; 507/240; 507/266] | 12 Claims |
| 7. A water based drilling fluid for use in drilling a subterranean well through a subterranean formation that swells in the
presence of water, the drilling fluid comprising:
an aqueous based continuous phase;
a weight material selected from the group consisting of barite, hematite, iron oxide, calcium carbonate, magnesium carbonate,
inorganic salts, calcium chloride, calcium bromide, magnesium chloride, zinc halides and combinations thereof;
an optional shale hydration inhibition agent; and
a shale encapsulator having the formula:
 in which x and y have a value so that the molecular weight of the cation is in the range of about 10,000 to about 200,000
AMU;
wherein B− is an anion selected from the group consisting of halogen ion, sulfate ion, nitrate ion, formate ion, citrate ion, acetate
ion, methylsulfonate ion, and mixtures thereof; and
wherein the shale hydration inhibition agent and the shale encapsulator are present in a ratio to each other and are in sufficient
concentrations to reduce the swelling of the subterranean formation in the presence of water.
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