Abstract

Reservoirs that contain acidic gases can lead to the corrosion of the drilling string and casing which could result in incessant down time and also increase the cost of drilling operation. This research work aimed at investigating the potential of using locally sourced materials such as Periwinkle Shell Ash (PSA) that can serve as substitutes to imported chemicals used in the industry, to help raise the mud pH to the API standard (9.5-12.5) whilst reducing the cost of drilling operation. Calcium hydroxide (Ca (OH2)) was extracted from Periwinkle Shell using two different process routes (via the calcination of the PSA and without it). Characterization tools were used to assess the functional groups present and the elemental composition of the periwinkle shell. Various laboratory equipment was used to observe the impact the additives would have on the mud properties (pH, mud weight, filtration characteristics and rheological properties) of the new drilling fluid. Results showed that as the mass of the synthesized Ca (OH2) from the calcined PSA, the uncalcined PSA and the commercial Ca (OH2) was increased, the pH of the mud samples was observed to have increased the pH of the base mud by 20.9%, 15.1% and 10%. Therefore, this research showed that the extracted Ca (OH2) acted primarily as a pH enhancer. However, the addition of Ca (OH2) from all sources exhibited poor filtration characteristics as there was high filtrate loss as the filtration time and the additive concentration increased which could affect the formulation and the performance of the drilling mud.

Key words: Keywords: Drilling fluids; Periwinkle shell Ash; Calcium hydroxide; Calcined eggshells; Uncalcined eggshells; pH.