Stage tools have been commonly used in North America for monobore completions to optimize economics. By cementing back the vertical and build sections of the wellbore, the requirement of the intermediate casing and liner hanger packer can be eliminated. An operator working in the K-1 carbonate formations of a massive field in eastern Saudi Arabia was examining a unique application of a stage tool to effectively cement and isolate a water-producing build section of a sidetracked lateral wellbore. The well incorporated a liner hanger packer with a multistage completion system. This paper will describe the distinct operational challenges encountered and how they were solved by redesigning an existing stage tool.

The well profile and construction specified that the liner had to be hung above the sidetrack point. Therefore, it was critical that the sequential operation of running the lower completion string, setting the liner hanger, releasing the liner hanger running tool, setting the open hole packers, cementing the upper liner section and then setting the top packer be completed with tremendous accuracy for a successful job. The operator selected a stage tool with a secondary contingency closure mechanism that did not limit the inside diameter through the system. This mechanism would ensure that all stages could still be stimulated if the secondary closure option was required. The use of the stage tool with a liner hanger system required some design modifications; the typical single foam plug, used to displace cement and close the tool in the standard version of the stage tool, was not an option. Instead, the operator required that a separate drill pipe dart and wiper plug assembly be used to displace cement through the drill pipe and the liner. The stage tool was, therefore, redesigned to close with a wiper plug launched from below the liner hanger packer.

After open hole conditioning, reaming and logging, the lower completion was run to setting depth and all equipment functioned without any issues. The problematic water producing zone was cemented and isolated and the stage tool was closed without the need to use the secondary closure mechanism. The stage tool was then milled out, leaving the well ready for stimulation. The redesigned tool enabled the operator to effectively cement the upper wellbore with no inside diameter restriction for stimulation.

This paper highlights the first introduction of cementing stage tool technology in conjunction with a multistage completion system to an operator in Saudi Arabia and the tool redesign required for accommodating a liner hanger packer in the wellbore. This method could also be applied to any type of lower completion such as sand management screens, inflow control devices or in conjunction with slotted or solid liners as an off-bottom cementing application.

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