A Comparative Study of the Methods of Determining Shale Volume in Radioactive Reservoirs of “AMA” Field, Niger Delta, Nigeria

Abstract

Shale effect in reservoir rocks is one of the most controversial problems in formation evaluation. The presence of highlyradioactive material in shaly sand reservoirs, overestimates the shale volume producing an overall pessimistic scenario of the reservoir quality. An accurate determination of shale volume impacts in the calculation of formation porosity and water saturation and therefore affects the original oil in place and reserves. This paper presents a comprehensive approach for handling this problem of radioactive shaly sand reservoirs. A combination method is provided to calculate the accurate value of shale volume for different scenarios from different shale volume computation methods. The study concluded that the combination method was the most reliable for estimating shale volume which fall within the acceptable range. It also concluded that the Clavier method was most reliable in oil bearing radioactive reservoirs while the resistivity method was most reliable in estimating shale volume in gas bearing radioactive reservoirs.