Abstract
Historically, 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 4½" 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.
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 window consisting of 3⅛" O.D. mud motor with a 3.2 degree bent housing and 3¾" X 4⅛" Bi-Center bit below the motor; (3) Retrieve the system with a hook. All of the objectives were successfully achieved.
Additionally, the paper will detail field runs of above described system along with lesson learned, conclusions and way forward.
