Abstract

A great advantage of using horizontal wells in production is reducing gas and water coning. It is very important for reservoir and production engineers to understand the reservoir and well parameters governing coning phenomena. Many published papers have already discussed this issue for vertical wells. However, only a few papers mentioned coning (cresting) performance in horizontal wells, especially for simultaneous gas/water coning in a gascap reservoir with bottom water drive. The objectives of this paper are (1) to compare gas and water coning performance in vertical and horizontal wells by using a numerical simulator, and (2) to investigate the key factors controlling the coning in horizontal wells.

It was found that the use of horizontal wells not only increases production rates but also greatly increases the oil recovery by reducing gas and water coning. The oil recovery from one horizontal well could be equivalent to that of two to four vertical wells. The key factors affecting the coning into horizontal wells are (1) well length, (2) well spacing, (3) gross production rate, (4) direction of wells in anisotropic reservoirs, (5) boundary effect, (6) well location, (7) aquifer size, and (8) ratio of vertical permeability to horizontal permeability.