Innovative casing exit system for CT/TT applications: System description, validation surface test and field runs

摘要

Historically, in CT/TT application, sidetracking through thecasing requires multiple trips to effectively produce a useablewindow for the next directional drilling assembly. The numberof trips needed depends upon the performance of the windowmilling system and the comfort level of the system operator.This paper presents an innovative one trip casing exit systemespecially tailored for the CT/TT operation. The systemincludes a hydraulically set anchor which can pass through arestriction and expands to a larger diameter, a whipstock, thatincorporates a hydraulically activated hinge mechanism,which provides the optimum trajectory for the mill withmultiple ramps for strategically guiding the milling tool, a leadmill with tightly spiraled blades dressed with cylindricalinserts for aggressive milling action and a retrieval tool in casethe system is to be recovered.The paper will also present a detail description of validationsurface test equipment for a 41/2” X 7” TT system, testprocedure and test results. The test set up included a 90 ft.long ‘I’ beam test bed, triplex pumping unit, data acquisitionsystem and video camera for recording the milled windowprofile and rat hole conditions.The initial test objectives were (1) to functionally test theanchor and hinge mechanism; (2) test the TT Whipstocksystem inside a test fixture and successfully mill a window;(3) evaluate various mill configurations utilizing the TTWhipstock system.The second test objectives were (1) to mill window in the 7”-26#, P-110 casing buried in a 3’ x 3’ x 40’ concrete block; (2)drift directional drilling assembly through the windowconsisting of 31/8” O.D. mud motor with a 3.2 degree benthousing and 33/4” X 41/8” Bi-Center bit below the motor; (3)Retrieve the system with a hook. All of the objectives weresuccessfully achieved.Additionally, the paper will detail field runs of abovedescribed system along with lesson learned, conclusions andway forward.