Innovative Casing Exit System for CT/TT Applications: System Description, Validation Surface Test and Field Runs

Abstract

TX 75083-3836 U.S.A., fax 01-972-952-9435. AbstractHistorically, in CT/TT application, sidetracking through the casing requires multiple trips to effectively produce a useable window for the next directional drilling assembly. The number of trips needed depends upon the performance of the window milling system and the comfort level of the system operator.This paper presents an innovative one trip casing exit system especially tailored for the CT/TT operation. The system includes a hydraulically set anchor which can pass through a restriction and expands to a larger diameter, a whipstock, that incorporates a hydraulically activated hinge mechanism, which provides the optimum trajectory for the mill with multiple ramps for strategically guiding the milling tool, a lead mill with tightly spiraled blades dressed with cylindrical inserts for aggressive milling action and a retrieval tool in case the system is to be recovered. The paper will also present a detail description of validation surface test equipment for a 4 1 / 2 " X 7" TT system, test procedure and test results. The test set up included a 90 ft. long 'I' beam test bed, triplex pumping unit, data acquisition system and video camera for recording the milled window profile and rat hole conditions.The initial test objectives were (1) to functionally test the anchor and hinge mechanism; (2) test the TT Whipstock system inside a test fixture and successfully mill a window;(3) evaluate various mill configurations utilizing the TT Whipstock system.