Experimental investigation at heavy light interface mixture of Reelwell ERD

Master's thesis in Petroleum engineeringDue to longer offset and large surface area exposure in a reservoir, extended reach drilling (ERD) is a method which is both cost effective and a well potential during the production phase. However, the present ERD method envelope is limited to about 12.3km. In order cross this envelope, the Stavanger based drilling company Reelwell has developed a ultra-long (>20km) ERD method solution. The method is under development and is in field scale testing phase. The results show that the technology is feasible and has several advantages over the conventional methods. Reelwell uses a range of different features to succeed with increasing the ERD envelope. The heavy over light concept is one of these. The concept is comprised of utilizing two different drilling fluids at the same time. Because of difference in density between the fluids and an inclined wellbore, an interface is created. This master thesis deals with an experimental study of this heavy light interface and its behavior when exposed to rotation from the drill string. In this thesis three test rigs were designed and constructed. Based on the Reelwell operational and fluid properties, a total of 31 experimental studies were carried out. The studies investigated several parameters that influenced the dynamics of the heavy light interface and the resulting mixing zone