Operators today face an ever-increasing demand for locating commercial reserves and producing those reserves with an emphasis on exploration and development costs. In addition to basic financial pressures, operators also strive to reduce the environmental impact of well-construction and production operations. Extended-reach drilling technology allows operators to reach recoverable reserves that were previously unreachable. Specifically, extended-reach drilling from a multipad wellsite allows significant portions of the well-construction costs to be distributed throughout multiple wells rather than being carried by an individual wellbore. Also, the capability to drill multiple wells from a single pad reduces the environmental impact of the drilling operation.

Extending the wellbore reach from a given pad depends on the location of the target formation. Depth, horizontal distance, and production type significantly affect the type of drilling program, as well as the casing-running operation. Casing flotation is a proven technology that has been deployed in multiple fields around the world to extend the attainable lateral reach of the casing-running operation. In many wells where flotation is required, the common limiting factor that determines the maximum step out that can be achieved is based on available hook load or weight in the near-vertical section of the well. However, when smaller casing strings are used, the limiting factor is not available weight, but rather the buckling limits of the casing. In some cases, slackoff loads with small casing strings cause helical buckling and lockup of the casing before reaching total depth (TD).

This paper documents the use of flotation technology in several wells where buckling limits and subsequent casing lockup was averted to allow successful casing-running operations to be performed without the requirement of costly premium torque-shouldered connections. Additionally, the paper presents improved processes used successfully that significantly increased operational efficiencies before cementing operations. Detailed prejob planning and computer simulations are provided to demonstrate the limits without casing flotation and the stepout achieved with casing flotation.

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