Casing setting depth optimisation based on well control considerations

Abstract

This study explores how casing setting depth can be optimised, based on well control considerations. The benefits of casing setting depth optimisation are: the likelihood of reaching the planned well depth is increased, and potentially, redundant casing(s) can be eliminated, hence decreasing the well construction cost. From the well control perspective, casing setting depth is influenced by kick tolerance (KT). Casing has to be set at the depth where the KT has decreased to the value dictated in the KT policy. The methodology of this study can be split into 3 parts, (1) a dynamic multiphase KT model versus Single Bubble Model; (2) effects of mud types on KT; (3) effects of wellbore underbalance on KT. The results show that the dynamic model yields a higher KT value than the SBM. Besides, oil based mud (OBM) produces a higher KT value than water based mud (WBM). Furthermore, while drilling, a higher pump flow rate yields a higher KT value than a lower pump flow rate. In conclusion, the use of a dynamic multiphase KT simulation software as a more accurate KT calculation tool, OBM and a higher pump flow rate while drilling yield a higher KT value, which optimises casing setting depth.