A review of critical coning rate correlations and identifying the most reliable equation

The study of coning in oil production is important because of huge water production associated with oil production around the world each year. Estimation of critical coning rate has been the subject of numerous studies and a number of correlations have been reported. This study presents a review of the current available methods for estimating critical coning rate for both vertical and horizontal wells. The various methods and correlations are compared and the assumptions on which they are based evaluated. Following comparison made between the correlations, the most reliable theories are identified for both vertical and horizontal wells separately. Among the correlations for vertical wells, this study recommends two implicit methods presented by Wheatley and Azar Nejad et al. They determined the oil potential distribution influenced by water cone with a remarkable accuracy. For horizontal wells, two methods, Joshi's equation and Rechem et al formula, are considered to be the most reliable. Joshi's equation provides lower estimates than Chaperon's correlation in which the water cone effect on oil potential was neglected. The Recham et al formula also gives a similar result. On the whole, the Rechem et al method is preferred.