Expandable Tubulars Enable Multizone Frac Packing in Open Hole

Abstract

Abstract Investigation is underway to enhance potential production rates by actualizing a method of frac-packing multi-zone slim holes and sidetracks using solid and slotted expandable casing. This innovative technique replaces the production liner and the cementing and perforating phases in a normal completion. The increased completion ID and flow areas provided by the expandable completion allow a significant increase in the frac-pack sand-screen size and associated production tubulars. The expanded completion liner itself offers more than a ten-fold increase in inflow area over a conventional perforated liner. These two factors, when combined, allow both reliable and improved production rates from 6 in. openhole sidetracked sand control wells requiring frac-packing. By utilizing these expandable slotted completion liners in conjunction with a newly developed solid expandable openhole packer system, the operator can selectively expand discrete production (or injection) zones and, with an appropriate frac-pack screen design, effectively control flow from the individual zones. Using selectively-expandable isolation devices allows the end user to decide their placement after the well evaluation data has been analyzed. This flexibility enables the end user to optimize the effectiveness of the completion. This paper will review the completion challenges with perforating and frac-packing inside small completion liners or open holes, the available technologies to perform isolation in the open hole, and the process and features associated with an expandable completion run prior to frac-packing. The results of ongoing testing and field trials of the expandable packer system will be presented and analyzed along with supporting modeling and simulation work. In effect, the new system allows an operator to perform an open-hole frac-pack inside a 6 in. sidetracked hole, obtain higher sustained production rates, and thereby, improve project economics over conventional techniques. This system, in some cases, will allow additional reserves recovery in difficult sand-control environments and revitalize maturing fields. Introduction Expandable sand screens have performed exceptionally since their introduction in 1999. These have been installed in both openhole and cased-hole environments and have been combined with both swellable packers and expandable solid zonal isolation devices to allow openhole zonal isolation between producing formations. Frac-pack completions combine tip-screenout hydraulic-fracture stimulation pumped with a gravel-pack screenpacker assembly in place. The TSO fracture creates a short, highly conductive fracture that is designed to bypass near-wellbore damage. The gravel-pack screen assembly prevents proppant flowback. The proppant/formation interface establishes a stable barrier, preventing sand production. This increase in effective wellbore radius reduces (and often eliminates) positive skin and mitigates factors related to fines-migration problems (Ellis 1998). With frac-pack applications in smaller wellbores (less than 8.5-in.), the restriction that swellable packers can introduce to the inside diameter (ID) within the completion can be limiting to optimum production of these economically sensitive reservoirs. An expandable packer that has been successfully introduced to remediate casing problems is now being combined with expandable slotted and conventional slotted liners to provide larger conduit completions. An Enabling Technology The expandable packer was developed to be primarily used as a remedial casing repair installation. It can be used to isolate perforations, split casing, and casing connection leaks. The expandable packer is considered to be a more economical solution for problematic zonal isolation, (squeeze isolation, well abandonment, etc.), as it provides better pass-through ID than conventional zonal isolation (bridge plugs, scab liners). A more optimum pass-through ID can be quite advantageous for smaller casing remediation.