Pushing the Boundaries: Tapping "Hard-to-Reach Oil" by Drilling High-Angle Deviated Wells

Abstract

The Greater Burgan Field is the oldest producing oil field of Kuwait. Till date, more than 1200 wells have been drilled in the field. Construction of surface production facilities, power line corridors, roads as well as office and housing complexes for its employees have put severe constraints on surface locations for drilling new wells. A fault block in the Ahmadi ridge that was expected to be geologically very prospective for hydrocarbon accumulation could not be accessed for a long time as it was below the Kuwait Oil Company's office complexes. Structural complexity and poor quality of seismic data around that area also added to the uncertainty. To reach the producing Wara and Burgan sands, the wells have to be drilled through the carbonate Dammam, Radhuma and Tayarat formations which are potential loss zones – more often than not leading to total mud loss. Deviated wells drilled so far in the field were, therefore, restricted to a maximum inclination of 45 degrees with the kick-off point located as deep as possible to minimize losses. This put a severe constraint on the horizontal drift achieved at pay zone level. Two high-angle deviated wells were successfully planned and drilled with inclinations of 50 degrees or more with shallow kick-off depths to achieve a horizontal drift of upto 1 km to reach the hydrocarbons locked up below the company office complexes. The higher inclinations also helped in maximizing the reservoir contact and net pay of more than 100 ft was encountered in both the wells.