Fast drilling invert emulsion drilling fluids
AssigneeO'Brien-Goins-Simpson & Associates
InventorsThad O. Walker, Jay P. Simpson, Harry L. Dearing
Life of this patent
Estimating the term…
Abstract
Disclosed are invert oil emulsion drilling fluids containing a non-toxic, biodegradable oil having a viscosity at 25.degree. C. of less than 1.5 centipoise, a flash point of at least 60.degree. C., an aniline point of at least 80.degree. C., and a content of aromatic hydrocarbons of less than 1% by volume. These drilling fluids have a low viscosity at the high shear rates imparted to a drilling fluid at the bit during drilling. This low bit viscosity provides for faster penetration rates. Such drilling fluids containing a temperature stabilizing additive exhibit superior thermal stability.
Claims8
A fast drilling invert oil emulsion drilling fluid having enhanced stability at elevated temperatures which comprises oil, water, a water-in-oil emulsifier, a weighting agent, a suspending agent, and a temperature stabilizing additive, wherein said oil is a refined petroleum oil fraction containing primarily straight chain paraffinic hydrocarbons and less than 1% by volume of aromatic hydrocarbons, having a viscosity less than 1.5 centipoises at 25.degree. C., a flash point of at least 60.degree. C., and an aniline point of at least 80.degree. C.;
- wherein said water contains up to a saturation amount of NaCl or CaCl.sub.2 ;
- wherein said suspending agent is an organophilic clay which comprises the reaction product of a clay selected from the group consisting of attapulgite, bentonite, hectorite, saponite, and sepiolite, and a quaternary ammonium salt having the structural formula:
- ##STR2## wherein R.sub.1, R.sub.2, R.sub.3, and R.sub.4 are independently selected from the group consisting of C.sub.a H.sub.2a+1-x B.sub.x, C.sub.b H.sub.2b-1-x B.sub.x, C.sub.6 H.sub.5-x B.sub.x CH.sub.2, and mixtures thereof, 1.ltoreq.a.ltoreq.30, 3.ltoreq.b.ltoreq.30, 0.ltoreq.x.ltoreq.2, B is a radical selected from the group consisting of OH, Cl, Br, C.sub.6 H.sub.5, and mixtures thereof, and A is a charge balancing anion, provided that at least one R contains at least 12 carbon atoms, and R.sub.1, R.sub.2, R.sub.3, and R.sub.4 collectively contain at least 20 carbon atoms;
- and wherein said temperature stabilizing additive contains from 2 to 6 carbon atoms and from 2 to 4 polar groups selected from the group consisting of OH, NH.sub.2, and mixtures thereof, per molecule.
Dependencies are inferred from the claim text.