Challenges associated with cementing horizontal wellbores, as well as the higher operational time and costsassociated with the cemented liner, plug and perf method, has resulted in many operators switching to open holemulti-stage system (OHMS) completions. In addition, production increases have been realized with OHMS due toaccess to the entire open hole lateral.To further optimize economics, cemented back monobore completions with OHMS are becoming the completionmethod of choice for operators. This is because they save on wellbore costs by eliminating the intermediatecasing. Instead, the build section of the wellbore is cemented back to surface using a stage tool once the liner isinstalled. In addition, the cemented back method allows for OHMS systems to be run in on liner eliminating theneed to trip out the running string and trip in the frac string. This paper outlines the operational procedure for cemented back monobore OHMS completions. Due to variousissues with conventional plug-type cementing stage tools a new hydraulically activated, mechanically closedcementing stage collar was designed to open/close without the use of a plug/dart. The new stage tool addressesthe operational issues encountered with conventional tools and further reduces costs by reducing rig time. Withthe new stage collar, there is no drill out of plugs and cement after the cementing operation, eliminating debristhat could be problematic for the OHMS functioning.The development of the new stage collar through lab testing and field trials is discussed. This technology hasbeen successfully used in various formations in Canada and the United States. This paper presents case studyexamples of installations in the Montney formation.
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