Shiftable Multistage Fracture Completion System Allows for More Options While Increasing Efficiency and Reducing Wellbore Interactions

摘要

With the industry focused on highly efficient completions, wells with water-producing and underper-forming zones create operational dilemmas that can ultimately reduce profitability. One way to improve efficiency is through the use of shiftable sleeve systems (SSS), which enable operators to stimulate multiple zones; then, later restimulate or produce specific zones without disturbing the entire wellbore. These features, which cannot be achieved with standard plug and perforation (PP) completions, add new options regarding how to best complete and produce the well. Ball-drop shiftable sleeves (BDSS) provide the same initial stimulation efficiency as other ball-drop sleeves (BDS) but can be shifted multiple times after the initial stimulation. To shut off problem zones, the baffles in the shiftable sleeves typically must be milled out. After the milling operation, a hydraulic shifting tool run on coiled tubing (CT) is used to close the sleeve in the affected zone. The shifter is run on either CT or a work string and positioned either above or below the target sleeve. The shifter is activated hydraulically and pulled or pushed against the baffle to shift the sleeve. The new high-expansion shifting tool (HEST) was designed to selectively shift BDSSs or shiftable pressure actuated sleeves (SPAS) by using the baffle in the tools as a shifting profile. This tool can shift multiple sleeves open or closed in the same run without the baffles being removed by a milling operation. Sleeves with baffle sizes of 1.800 in. and greater can be shifted with the HEST. When used with dissolvable balls, the HEST provides the ability to shift BDSS without a milling operation. The shiftable sleeve then performs as a standard production sleeve, enabling selective flowback of zones or shut-in of trouble zones, reducing operators' time, money spent, and additional risks associated with milling operations. The introduction of several new tools and processes enables operators to reduce downtime and operational risks. Operators can also add new completion options, which have the ability to extend the life of the well in ways not currently used. This paper provides an in-depth description of those tools and processes and highlights the returns and gains achieved with the methods discussed.