Stage Multiplier Technology Provides Ultrahigh Stage Numbers

Abstract

Young Technology Showcase In December 2011, a record-setting 60-stage openhole fracturing system was installed in the Marcellus Shale in western Pennsylvania. One of the key technologies that enabled this application is a new stage multiplier device called the Packers Plus RepeaterPORT sleeve, which allows the same sized ball to be dropped multiple times. Initially, reservoir fracture modeling indicated that a relatively small number of planar fractures would adequately drain unconventional resource plays such as shale and ultratight rock for both oil and gas. However, empirical evidence has shown that this is not the case. No matter which completion technique is used, stage numbers have been increasing and spacing between fractures has been decreasing. In many cases, however, operational efficiencies are nearing an economic limit for conventional cemented liners and plug-and-perforation completions. Long planar fractures may not be the best approach to effective resource recovery; instead, shorter fractures, smaller fluid volumes, and higher stage numbers have increased productivity and ultimate recovery numbers by as much as 50%. In addition, liquids and condensate numbers (bbl condensate/MMcf/D of gas) increase with openhole completions and ultrahigh stage density. Technology Description The stage multiplier technology operates by allowing the ball to pass through the port, putting it through a passive shift that does not open the port but instead moves it to the next operating position. Subsequent balls of the same size will either provide another passive shift or prime the port to be opened with the next ball. In the latter case, the ball will move the port to an active shift position allowing the next ball to shift it to the open position. This technology creates a number of advantages. First, the ability to run the same size ball multiple times enables an increase in stage numbers—currently up to 60 stages in 5½-in. casing. A second advantage is that the smallest port size can remain relatively large compared with other approaches, reducing accumulated friction from fluid passing through multiple port restrictions. In addition, access with coiled tubing is enhanced for operations such as production logging and well cleanout. Third, operational efficiency is greatly enhanced by allowing uninterrupted stage-to-stage advancement. Furthermore, pumping rates can be reduced, saving on hydraulic horsepower and equipment requirements, because single intervals are being treated per stage rather than three or four perforation clusters. This means that the effective rate will be similar for individual intervals, but the total pump rate at surface can be reduced by approximately one-third, thus saving on surface treating pressure and friction while pumping.