Effect of 2-Phase Oil-Water Flow and Friction Pressure Loss in the Wellbore on Water Cresting in Horizontal Wells

Horizontal well application to mitigate water coning problems have gained wide industry acceptance. However, horizontal wells themselves have not been free from water coning (cresting) problems. A major challenge before industry operators is the effective modeling of water crest development in horizontal wells. More often, mathematical models developed for fluid flow in horizontal pipes have been adopted for modeling horizontal well performance but these have been largely inadequate. This paper presents a more encompassing tool for evaluating the performance of horizontal wells with bottom water drive which incorporates all the effects of perforations, 2-phase liquid-liquid flow and axial influx of fluid into the wellbore. A new value of equivalent pipe roughness function is developed for use in the numerical simulators to accommodate the inadequacies of the current commercial softwares. The empirical results using published data from the North Sea indicate a more practical representation of the phenomenon of water cresting in horizontal wells and the level of severity. Two major factors affected by the application of the new approach are; a reduction in the time to water breakthrough as previously predicted by analytical tools, and an effective representation of the geometry of water cresting in horizontal wells similar to field experiences. The paper also shows that direct application of horizontal pipe models in horizontal well is grossly inadequate. Finally it shows use of horizontal wells in the development of reservoirs underlain by water needs adequate evaluation.