Description A Coriolis-type mud flowmeter was run on an exploratory well to obtain Real-Time identification of open formation fractures in an otherwise tight carbonate reservoir. The well was drilled with oil base mud which does not enable accurate flow measurement with other sensor types. This was the first time that accurate fracture detection via advanced flowmeters was performed in oil base mud. Application Tight, fractured carbonate reservoirs are the prime targets for hydrocarbon exploration in Kuwait. Sustained economic production from carbonate reservoirs depends entirely on the connectivity of open fracture networks. Hence, proper evaluation of fractures is key to exploration of these reservoirs. Cores and image logs are used for fracture characterization, but they do not provide Real-Time response. The patterns in the variations of mud flow, instead, enable to identify open fractures. Results, Observations, Conclusions The system has proven to be the only source of Real-Time information on the presence of open fractures while drilling. It has also been utilized as an early kick detection tool. The paper presents a series of events in which these results are substantiated. These results have enabled to confirm and further develop interpretation models for flow behaviour in relation to fluid exchange between the borehole and the formation. Furthermore, in order to maximize the quality of the flow data, a correct sensor installation design and execution has proved critical. Significance of Subject Matter No open hole logging was possible in the zone of interest in the pilot well due to high pressure and associated drilling complications. In this situation, information from mud flow anomalies was the only source for identification of open fractures. This information was utilized to identify the well test interval.


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