When water based muds fail to ensure that a usable hole is drilled, oil based mud formulated with No.2 diesel is adopted. Because No. 2 diesel is toxic, the oil and gas industry is looking for other alternatives to it. One of such alternatives is the use of vegetable oils. These vegetable oils are relatively more expensive than the No. 2 diesel; hence their use would ultimately increase the cost of drilling fluids. There are however many types of these vegetable oils. These vegetable oils vary in physical and chemical properties and in their cost. This paper undertook an investigation into the cost, properties and availability of these vegetable oils for use in drilling mud formulation; it chronicled the trend of researches available on the use of vegetable oils as drilling fluids with the findings from each researcher presented. This paper also presents a detailed cost benefit analysis of major vegetable oils used as drilling muds. To make the work comprehensive, an evaluation of the viability of each vegetable oil to achieve the objectives of cost effectiveness, availability, and good rheological and filtration properties were evaluated. The results showed that of all the vegetable oils studied, olive oil ranked the least in meeting all of these objectives while palm oil, soybean oil followed by rapeseed oil fulfilled all of the objectives to a considerable extent. This paper therefore offers an all-inclusive portfolio of cost related issues that border on the use of vegetable oils as drilling muds which would be useful to wellbore drillers in particular and the E & P industry at large.
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