New chemistry for chromium-free bentonite drilling fluids stable at high temperatures

Book · Wed Nov 01 04:00:00 EST 1995

OSTI ID:113536

Burrafato, G; Miano, F; Carminati, S; Lockhart, T P

The broad substitution of aqueous drilling fluids for oil-based muds will require that the performance limitations of current aqueous muds be overcome. The research described in this paper is focused on the most commonly-used aqueous drilling fluids, lignosulfonate (LSO{sub 3})-dispersed bentonite muds, and addresses two important issues that restrict their wider use: their limited stability at elevated temperature, and their reliance on chromium-containing additives (Cr-LSO{sub 3} and Cr-lignite) for control of their rheological properties. In this paper, new hypotheses regarding the mode of action of Cr(VI) and Cr(III) in Cr-LSO{sub 3}/bentonite muds are formulated on the basis of new and published experimental observations. Of primary importance are the ideas that (1) LSO{sub 3}-bound Cr(III) is the form which enhances the thinning power of LSO{sub 3} and (2) Cr(VI) stabilizes LSO{sub 3}/bentonite muds primarily by acting as a latent source of Cr(III). Acting on these hypotheses, it has been found that Cr(III) complexes of appropriate kinetic stability can duplicate the rheology-stabilizing function of Cr(VI). Further pursuit of this coordination chemical approach has led to the identification of a family of Zr(IV) complexes with which chromium-free drilling fluids of outstanding rheological stability can be prepared. The general chemical factors influencing the rheology-stabilizing activity of metal ion complexes are examined. Finally, the unexpected and remarkable thinning power of the Zr(IV) citrate complex is described and its implications for the formulation of novel drilling fluids are briefly discussed.

• OSTI ID: 113536
• Report Number(s): CONF-950207--
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
ADDITIVES
AQUEOUS SOLUTIONS
CHEMICAL COMPOSITION
CHROMIUM COMPOUNDS
DRILLING FLUIDS
EXPERIMENTAL DATA
LAND POLLUTION ABATEMENT
MATERIAL SUBSTITUTION
OIL WELLS
RHEOLOGY
SULFONATES
THERMAL DEGRADATION
WELL DRILLING
ZIRCONIUM COMPOUNDS