Well control during extended reach drilling - conventional drilling compared to the reelwell drilling method

Abstract

Well control is always of great importance during well operations. The main purpose of well control is to keep downhole pressures in the operating window between pore and fracture pressure. In the case of a well control situation where either the formation is fractured causing loss of circulation or the pressure in the well drops below pore pressure causing a kick, measures have to be taken in order to get the situation under control. When drilling horizontal and extended reach wells the same basic principles of well control apply, but also other aspects have to be considered. In this thesis the basics of well control has been discussed, along with considerations by use in Extended Reach Drilling, both conventionally and for the Reelwell Drilling Method, which is a new drilling method developed by REELWELLTM. The first part of the thesis contains literature review of well-established well control procedures and an overview of the Reelwell Drilling Method. Due to RDM being a new drilling method, well control issues haven’t been studied to the same extent as for conventional, and less literature exists on the matter. The second part consists of simulation studies performed for 2 extended reach case wells. Landmark Wellplan was used for the conventional simulations, while DrillSIM-5 was used for the RDM simulations. The focus of the simulations has been on circulating kicks of different volumes out of the well. The effect of different mud densities and kick intensities was also included for the Wellplan simulations.