In Qatar, Occidental Petroleum is faced with the task of drilling high angle wells through an unstable formation before entering the productive zone. Casing while drilling is becoming a powerful tool in mitigating both lost circulation as well as wellbore stability issues. The unstable Nahr Umr formation lies directly above the Shuaiba payzone and is typically drilled with 12-1/4-in. bits. The Nahr Umr shale tends to slough in shortly after drilling, leading to stuck BHA's and difficulty running 9-5/8-in. casing. Exposure time with the Nahr Umr is increased due to the requirement of continuous angle building and turning to land near horizontal. This paper details the case history of directional casing drilling (DCD) that have been utilized in offshore Qatar and the lessons learned
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