Abstract

The use of horizontal drilling to improve oil recovery in coning situations is a technology that is gaining widespread application. This paper adds to the data base by evaluating the results of a horizontal well in a highly heterogeneous carbonate reservoir where both vertical gas coning and differential horizontal cusping occur. The complexities of designing, completing and testing the well are presented.

The results discussed in this paper show that in situations where geologic uncertainty exist, a horizontal well can be repositioned during drilling. However, the additional cost involved can be more than offset by refining the seismic description in advance. The completion design should be kept as flexible as possible so that production can be made to converge on the optimum sections of the horizontal wellbore. A combination of logging, buildup and production testing before and during startup will help identify potential undesirable gas breakthrough. This can then be forestalled by refining the completion design accordingly.