An Overview of Top-Drive Drilling System Applications and Experiences

Abstract

Top-drive drilling has become one of the new technologies of the 1980's. Application of this seemingly old concept is now widespread in most offshore areas of the world. Top-drive drilling may be one of the biggest changes made to the rotary-drilling method since the development of the rotary table.This paper analyzes why the concept of drilling with top drive, similar to the very old concept of a power swivel, has suddenly become so successful. Applications and locations are presented to show the system's worldwide use. Results of more than 50 systems currently in operation are analyzed to present benefits and trends.The results show surprising benefits for almost any type of well, and overall time savings generally exceed 20%. Benefits from the extended-reach potential associated with top drives are enormous. These results explain the primary motivation for most applications of the system. Recent Top-Drive DevelopmentsDrilling with a rotary table requires a host of auxiliary equipment not normally identified with the drilling process, as well as those items obvious to the method. Those components normally associated with rotary-table drilling are the kelly, the kelly bushing, the swivel, and the rotary table. Components that are not frequently thought to be significant make the difference between operational efficiency and difficult, if not impossible, alternatives.