Casing drilling proves successful in South Texas

Conoco has used Tesco’s Casing Drilling* system to drill 17 development wells in Lobo field of South Texas since mid-2001. The intermediate and production sections of Lobo wells often require time for hole conditioning, lost circulation, gas influxes, stuck pipe and running casing. The system has significantly reduced these downhole problems by casing the well as it is drilled. This is accomplished by using casing as the drill pipe. Once the casing point is reached, the casing is cemented in place without tripping pipe, unless the production casing is partially tripped for openhole logs. Negligible time has been required for hole conditioning and lost circulation. Gas influx has been less of a problem while drilling with casing than when drilling conventionally. Performance on the first 10 casing drilled wells shows that the technology provides time savings of 8% to 33%.