This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 170641, “The Evolution, Optimization, and Experience of Multistage- Fracturing Completions in a North Sea Environment,” by T.R. Koløy, K. Brække, T. Sørheim, and P. Lønning, Trican, prepared for the 2014 SPE Annual Technical Conference and Exhibition, Amsterdam, 27–29 October. The paper has not been peer reviewed.
This paper reviews two newly developed novel completion systems that significantly reduce time spent performing multistage stimulation in environments where cost and consequence of failure are high. Both coiled-tubing and wireline-manipulated sliding-sleeve/valve systems and balldrop-actuated systems have been developed and deployed, depending on the various completion and stimulation challenges faced. Since their first installation in 2009, these systems have been proven and refined in multiple wells for two major operators.
Background
For many of the fields requiring stimulation in the North Sea, cemented plug-and- perforation (plug-and-perf) completions have been used historically. It is a flexible solution in terms of the various types of stimulation designs that can be accommodated. However, because of the large number of perforating runs required, the bridge-plug setting, the retrieving or milling involved, and the clean out runs required, it is also a very time-consuming option. The turnaround times per stage have been widely documented and often range from 3 to 7 days.
Prototype Development, Testing, and Qualification. Sliding sleeves have been used for flow-control purposes in oil and gas wells for decades. Although sliding sleeves are simple in design, many users have questioned their reliability, and they did not see much use for fracturing operations until the mid-2000s, when ball-drop-actuated sliding sleeves entered the market. The preferred method for stimulating a reservoir with a cemented liner—stage by stage—has been with plug-and-perf methods. Plug-and-perf provides a proven method of initial stimulation, compartment for compartment, but provides no solution for efficient production management over the life of the well.
