Abstract: Geological Analysis of Early Water Production in Horizontal Wells in the Middle East

SAPRU, AJAY

The intensive drilling of horizontal wells within the Middle East region has had significant economical and technical merits. Some drawbacks with horizontal wells, however, soon became apparent, particularly the unexpected and early water breakthrough. Initially many horizontal wells were drilled to avoid water coning in producing horizons, but early water production from horizontal wells was soon recognized to be a surprisingly common phenomenon even in fields where water production had not been encountered or anticipated. Thorough geological analysis of these horizontal wells suggests that open, permeable faults are the most common cause of early water production and it was also confirmed that there are many more faults encountered than had been originally mapped even with recently acquired 3-D seismic data.

The 3-D seismic is critical to studies of faulted reservoirs, and even though it is not revealing all of the faults present, the orientations and distribution of the larger faults defined by 3-D helps in modeling and interpreting the smaller faults. Geological characterization of the fracture/fault systems in horizontal wells is critical to the completion design to prevent early water or unwanted gas production for present and future wells. The open /permeable faults must be identified and isolated before they are allowed to flow water or gas into either in the oil zone or the horizontal wellbore itself. The planning of future horizontal wells in a field should be decided on the basis of fracture and fault orientation.

AAPG Search and Discovery Article #90942©1997 AAPG International Conference and Exhibition, Vienna, Austria