Precise Well Placement using Rotary Steerable Systems and LWD Measurements

Abstract

Abstract This paper demonstrates profitable geosteering of a Central North Sea, UK horizontal well by using a Rotary Steerable System (RSS) together with new generation azimuthal Logging While Drilling (LWD) tools. The nature of the Tertiary Turbidite reservoir meant that to be commercial the following criteria had to be met: Maximise stand-off from an oil water contact within a sand unit with a circa 50 ft oil column.Achieve 1500-2000 ft of good quality reservoir.While maintaining the stand-off from the OWC, make a corresponding azimuth turn in order to follow the crestal dome structures of the reservoir trap.Avoid the risk of stuck pipe by carefully monitoring real time drilling and well data and by using RSS technology. During drilling of the well, correlation software enabled comparison of offset well and real time LWD data and visualisation of the position of the well in the reservoir sequence. This modelling complemented wellsite biostratigraphic and geological correlation work and enabled changes to the trajectory to be planned, which were then achieved while constantly rotating using the RSS tool. Azimuthal density measurements were used in real time and as post-well image logs for structural dip and fault interpretation. The well was geosteered into a sweet spot within 5 ft of the reservoir roof as much as 56 ft from the OWC. The RSS tool completed the well in a single run of 3844 ft with an average ROP of 68 ft / hr and with no stuck pipe problems. The target of 1500-2000 ft of pay was met with 1980 ft of >20 % porosity sand and 88% nett to gross. Water saturation of 10% was much lower than expected and the well is currently producing at 11,500 bopd. This well demonstrates the combinability of the latest RSS and LWD technology to successfully meet ever-demanding drilling and geological objectives under circumstances of high-economic risk and ultimately maximise potential well production.