Dealing with higher than planned pore pressures, slim drilling margins and depleted zones in the same wellbore can quickly compound an already difficult deepwater drilling environment. Current market demands for oil and gas are placing more focus on deepwater development of existing reserves. Operators have had to utilize enabling technologies that are robust enough to address multiple problems to develop deepwater reserves that are difficult to access.
This paper describes a recent example of this dilemma when a deepwater operator successfully employed a solid expandable tubular system to isolate both overpressured and depleted sands The solid expandable system facilitated reaching the well objectives with a large hole size for maximize production rates. Over 6,865 ft (2,092m) of 7-5/8 × 9-5/8 in. expandable openhole liner allowed the operator to drill through both overpressured and depleted sands to an intermediate and unplanned casing point. Subsequent drilling operations below the expandable liner enabled the operator to reach the target zone and case the well with a 7 in. flush-joint production liner. Without the expandable installation, the operator would have been restricted to a maximum 5-1/2 in. casing at total depth (TD). Comparatively, 7 in. casing allowed the use of larger completion equipment providing Nexen Petroleum U.S.A., Inc., with significant additional production while reducing the mechanical risks associated with working inside smaller casing.
The solid expandable tubular operating envelope provides a robust technology for operators who need a responsive system that addresses conditions proven to hinder drilling objectives. This paper will describe the conditions that led to selecting the solid expandable solution and detail the challenges mitigated with the installation of this record-setting system. In addition, this paper will focus on how solid expandable tubulars are applicable in extremely difficult drilling conditions and also how these tubulars can reduce the risks and costs associated with deepwater drilling.