ABSTRACT
A reduction in the environmental footprint from drilling operations can best be addressed by minimizing the sources of that footprint. One of the principal sources of possible environmental damage is drilling fluid and drill solid discharge. The toxicity as measured by acute and/ or sub-chronic testing regimes depends on the composition of the drilling fluid/ drill solids slurry. The trend within the drilling fluids industry has been to direct its attention to finding drilling fluid products which alone and in combination are considered to be non-toxic as determined by required testing procedures. This paper goes on to describe a parallel approach in which the total volume of chemicals discharged (whether considered toxic or benign) is reduced. Both approaches can be considered complimentary. The reduction in volume/ mass of discharge is achieved by increased monitoring of both drilling fluid properties, composition and solids control operational efficiency, (Ref 1). Additionally the increased monitoring allows less complicated formulations to be used to produce the desired drilling fluid properties; as specified by the mud programme. The need for more complete rigsite monitoring packages, see (Ref 2), will become more important as oilbased muds are replaced by waterbased mud for difficult drilling situations with stricter environmental regulations on discharge of drilling waste. The paper also outlines how the optimization of the drilling fluid operation was linked to a reduction in drilling fluid costs at the sametime maintaining drilling efficiency.
