A Review of Horizontal Drilling in (PDO) Exploration (1990-1993)

Abstract

In Petroleum Development Oman (PDO), horizontal drilling started in 1986 with a three-well trial in north Oman, targeted at chalky oil reservoirs prone to gas/water coning and low production rates. The results were not sufficiently encouraging to lead to further activity in the short term. Horizontal well technology evolved rapidly, however, and in 190 PDO embarked on a more ambitious trial by the petroleum engineering and exploration functions of eight wells in a variety of reservoirs in north and south Oman. The results were extremely positive to the extent that this trial has led to continuous horizontal drilling activity. By the end of the 1992, PDO will have drilled nearly 90 horizontal wells and seem likely to drill at least 50 such wells each year for the foreseeable future, 10 of which will be for exploration/exploratory appraisal purposes. The exploration horizontal wells have been drilled in unconnected accumulations and new discoveries with a two-fold objective: first of all to test the scope of productivity improvement for (1) thin oil columns in reservoirs with strong bottom-water drive, (2) good porosity and low-permeability oil-bearing reservoirs with depletion as a drive mechanism, (3) heavy/highly viscous oil-bearing fractured carbonate reservoirs, and (4) poorly connected/developedmore » channels, and second to outline the lateral extent of reservoir development.« less