SEPARATION AND RECOVERY FOR RE-USE OF DRILLING FLUIDS
Destabilization and separation of Oil-based drilling fluids
The recovery for re-use of valuable elements from oil-based fluids contributes to environmental stewardship, circular economy, and optimal waste treatment
in Norway, approximately 180,000 ton of high-priced oil-based mud and completion fluids return to shore after having been used offshore.
The used oil-based mud, actually a valuable resource, could be treated, upgraded and reused. Very often, instead, the treatment is not carried out because the used oil-based mud (OBM), even after the upgrading, is deemed unsuitable for the stringent requirements of the drilling operations.
A substantial amount of OBM is therefore classified as waste. The OBM waste handling costs around USD $300 per ton, the figure is based on data received from Norsk Gjenvinning AS. Furthermore, some used oil-based drilling and completion fluids are stored in tanks for several years as they contain highly expensive chemicals.
Norwegian Technology AS agreed with Baker Hughes Inc to treat 330 m3 of low solid OBM that had been stored in tanks for several months. The mud contained 60% of expensive brine and around 40% of oil (by volume). The mud was treated and approximately 60% brine, 20% oil and 20% sludge were recovered.
The price of the OBM is a function of its composition, illustrated in the figure on the right (IPIECA/OGP, 2009). The quantities of the various components can vary significantly, e.g. the oil/brine ratio can range between 60/40 and 90/10 (McCosh, Kapila, Dixit, Way & Phipps, 2009), while the weighting material can sometimes be close to zero.
Low oil prices
Low oil prices, difficult drilling settings and stricter environmental regulations promote the development of new practices in the oil and gas industry. The optimization of the waste treatment can contribute to significant cost savings. OBM is an expensive drilling fluid which is necessary in many drilling operations.
The price of materials used in the OBM can range from USD $ 250 to 2 500 per m3 (Melton et al., 2004).