Texas United Chemical Company, LLC

Jeffrey S Lay

James W Dobson, Jr

Kim O Tresco

The invention provides clay-free, preferably biopolymer free, well drilling and servicing fluids comprising an aqueous divalent cation-containig water soluble salt, a bridging agent, and a pre-gelatinized crosslinked amylopectin starch suspending agent and fluid loss control additive. The concentration of the starch derivative is sufficient to provide the fluid with the following charactristics: (a) a low shear rate viscosity less than about 10,000 centipoise; (b) a high shear rate viscosity at 511 sec in the range from about 15 to about 70 centipoise measured at 120&deg; F.; (c) a fluid loss less than about 10 milliliters as measured at 185&deg; F. and 250 psi differential pressure across a 5 micron disk for 30 minutes; and (d) anti-settling characteristics as exhibited upon static aging the fluid for 16 hours at 185&deg; F. The low shear rate viscosity of the fluids can be increased without increasing the high shear rate viscosity above about 70 centipoise by incorporating magnesium oxide and/or dipotassium hydrogen phosphate in the fluids. The invention also provides a method of making the clay-free well drilling and servicing fluid and a process of drilling, completing, and working over a well with the clay-free fluid.

Divalent cation-containing well drilling and servicing fluids

The invention provides clay-free, preferably biopolymer free, well drilling and servicing fluids comprising an aqueous divalent cation-containing water soluble salt, a bridging agent, and a pre-gelatinized crosslinked amylopectin starch suspending agent and fluid loss control additive. The concentration of the starch derivative is sufficient to provide the fluid with the following charactersitics: (a) a low shear rate viscosity less than about 10,000 centipoise; (b) a high shear rate viscosity at 511 sec,in the range from about 15 to about 70 centipoise measured at 120&deg; F.; (c) a fluid loss less than about 10 milliliters as measured at 185&deg; F. and 250 psi differential pressure across a 5 micron disk for 30 minutes; and (d) anti-settling characteristics as exhibited upon static aging the fluid for 16 hours at 185&deg; F.

Growing community of inventors

Houston, TX, United States of America

Jeffrey S Lay