Abstract

In the presence of an active aquifer, water coning in a vertical wells phenomenon may cause a significant Reduction of the well productivity, thus reducing the ultimate oil recovery, increasing the cost of production operations, and arising environmental problems related to water disposal. After water breakthrough at a well, the water phase may become the dominant one, and the well must be shut in because oil production becomes uneconomically. A wide number of analytical approaches derived for homogeneous formations were developed to analyse coning phenomena and to define a valid methodology to evaluate the critical rate to consider the impact of formation heterogeneity and flow barrier distribution the combination of geological and flow simulation software. The critical rate is the maximum oil rate that can be produced before water breakthrough occurs. However, due to the complexity of the problem, a rigorous approach of general validity could not be identified. The present study was aimed at providing an exhaustive comparison among the most used analytical methods and the results obtained by numerical simulation for water coning and prediction for a number of possible scenarios to quantify the water coning potential recovery dynamics prior to and after water breakthrough, and water cut control with production rate in the field assessing and well productivity investigates dynamics of productivity loss in the presence of uncertainty of real field geological properties by optimizing new wells targeting and well operation parameter, which provided an increase of water-free periods of the wells. Two set of sensitivities were conducted in this evaluation the first one refers to the reservoir characterization (variation of relative permeability curve, wettability, transition zone, capillary effect, vertical to horizontal permeability ratio distribution) and the second to the completion strategy and well operation parameter (perforation interval, standoff, and geological zone). the single well model showed that the favourable mobility ratio, permeability profile and fluid characteristics has huge impact on efficient displacement and to minimizes the water coning tendency in the field the recommended stand-off and drawdown for future well therefore the high off take rates could be achieved with no impact on ultimate recovery considering the maximum efficient rate MER allowed is directly related to the productivity index of the well.

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