Technical Improvements in Mill Profile Design and Cutting Structures: Case Histories and Developments

Abstract

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractThe ever increasing operator demands and objectives to mill fast and efficient windows has led to the development of innovative milling technology. New lead mill profiles and cutting structures have replaced old crushed carbide technology. The new design utilizes inserts brazed into pockets machined in the mill head. Mills dressed with the new cutting structure are able to effectively mill a casing window and drill formation rat hole in less time than it took with the welded-on crushed carbide technology.With this new design, operators are now afforded an option. In medium to hard formations, the new cutting structure can be used to mill the window and drill rat hole in one trip. While sidetracking in formations with high compressive strengths, Polycrystalline Diamond Compact (PDC) inserts can be utilized. The use of the new cutting structure in a one trip sidetrack system can result in substantial cost savings, improved milling reliability and a higher quality window.The combination of new cutting elements and mill profile has proved to be economically sound allowing for consistency of product manufacturing and has eliminated the potential variances inherent in the welding processes. The system design and cutting structure reduces torsional resistance providing for smoother in-gauged milled windows in one trip.This paper updates an earlier paper with the concepts of using the new cutting structure and presents the new technology and recent case histories of four sidetrack operations.