Field Testing and Applications of a Smart Flow Diverter

Abstract

In liner drilling operations, the annular velocity of the drilling fluid drops significantly when it transits from the narrow cross section of the openhole-liner annulus into the increased annular volume between the casing and the drillpipe. The reduced annular velocity above the liner can cause critical hole cleaning problems that can jeopardize the entire drilling operation and, therefore, must be managed. To effectively mitigate this problem, a major operator and service company jointly developed and tested a smart flow diverter that can be positioned in the drillstring directly above the liner running tool. The flow diverter (FLD) is designed as a standalone tool that can be placed anywhere in the drillstring and is independent of the measurement-while-drilling (MWD) service-supplier. It can be used in different applications, e.g. under-reaming operations and liners without tieback, where enhanced, continuous hole cleaning is required. The fluid bypass of the flow diverter is simply activated either by drillstring rotation and flow or by a flow pattern signal if string rotation is not possible. These surface manipulations are recognized and interpreted by the flow diverter sensors and electronics. The concept enables an unlimited amount of activations and both activation principles can be incorporated into standard connection procedures, thereby eliminating nonproductive time (NPT). The FLD went through extensive testing and was run in steerable drilling liner and in other applications. The paper presents the features and activation principle of the technology, its benefits and field experience in combination with steerable drilling liner (SDL) technology and how the utilization of the technology in an underreamer application resulted in an optimized bottomhole assembly (BHA) design preventing previously experienced formation washouts.