Performance of Butyl Acetate as Biodegradable Environmentally Friendly Oil Based Drilling Fluid

Abstract

Diesel oil-based drilling fluid has been found to be toxic and harmful to environment, mostly due to its cyclic aromatic compound. A lot of research had been done and esters found to be among the promising alternatives, that meets the requirements of a suitable drilling fluid, in terms of technical performance and stability when in wellbore. The study showed that Butyl Acetate is highly sensitive to variation of lime concentration, oil/water ratio, temperature and water salinity, where its plastic viscosity increased dramatically. Butyl Acetate mud system’s performance was compared to palm oil-derived esters with large carbon chains such as Methyl Laurate and Isopropyl Laurate, that are proven to be more stable to alkaline hydrolysis with small increment of plastic viscosities. Commercial base oils that are commonly used in the oil and gas industry such as PETRONAS MG3DF™ and Shell GTL Saraline 185v to were used compare the performance of Butyl Acetate and serve as a control unit, with reference to the API 13B guideline for drilling fluid properties range. Butyl Acetate also showed the highest filtrate loss among all of the oil tested. The larger molecular size of Isopropyl Laurate and Methyl Laurate allows less molecules to pass through the mud cake, compared to the smaller Butyl Acetate molecules which resulted in increase of filtrate loss. The toxicity was observed when all twelve Poecilia sphenops fishes that came in contact with the ester, have died within the first three hours. Even though performance of Butyl Acetate as drilling fluid looks promising, it still poise some problem such as high fluid loss and the cost of raw Butyl Acetate is still considerably more expensive than Diesel.