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Technical Paper: CwD Technology Improves Economics in Tight Gas Exploration Project in the Sultanate of Oman

Society: SPE
Paper Number: 177762
Presentation Date: 2015
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Abstract

In Sultanate of Oman, use of casing-while-drilling (CwD) service improved project key indicators for a complex unconventional tight gas exploration project. The technology has been used in 12 wells to date, and the improvement progress has been tracked from the first well. Reaching first hydrocarbon-bearing zone in northern Oman required drilling through the unstable think Shagri shale, principal element of the Fiqa Formation. Formation swelling and collapse were encountered in the first exploratory wells, which caused significant nonproductive time for reaming and additional trips in hole. To complicate the situation, the naturally fractured UmUeR Formation, Located above Shargi, could cause either a partial or total losses when drilling conventionally. CwD technology was the selected drilling approach for the subsequent wells in an attempt to mitigate these issues. Although drilling through unstable Shagri shale was still possible with conventional drilling, reaming, stuck pipe and unplanned casing depth become routine operations. The proposed drilling approach proved to be an economically sound alternative to conventional techniques used previously in the field to reduce risk and associated cost. In the Sultanate of Oman, the CwD technology reduced the time of drilling and casing surface holes by 40% in comparison to the field average when using the conventional drilling technique. After drilling 12 subsequent wells with CwD technology, the operations team reported saving of up to 4.94 days per well. Efficiency analyses were conducted, and the technique was fine-tuned for specific conditions.

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