Exploratory offshore well drilled to TD without NPT due to real-time fluids monitoring

A leading operator planned to drill an exploratory well offshore Eastern Canada in the North Atlantic using RheoProfiler™ automated rheometer for monitoring and PRESSPRO RT™ real-time downhole performance measurement software. From this implementation to total depth (TD), there was no downtime nor delays in real-time data. In addition, the rheometer system and software enabled an increase from just two fluid checks to four three-temperature fluid checks per day. The well was drilled to TD without significant nonproductive time (NPT).

An operator faced a short drilling window in a deepwater HPHT exploration well, which required special attention to equivalent circulating density (ECD), emergency shutdown (ESD) procedures while drilling and tripping, and fluid rheology checks at multiple points due to the wide range for fluid column temperatures. Significant NPT from issues like a stuck pipe, plugging, or other pullouts had to be kept to a minimum.

SLB recommended RheoProfiler rheometer and PRESSPRO RT software to make hydraulic forecasts and updates throughout drilling and tripping operations. The RheoProfiler rheometer provides a thorough system that tests density and rheological characteristics of all fluid types. In addition, OptiWel™ well construction performance service was implemented combined with the RheGuard X™ narrow-window flat rheology drilling fluid system.

The combination of OptiWell service, RheGuard X system, RheoProfiler rheometer, and PRESSPRO RT software monitored the fluids and tripping to TD with limited downtime. Four temperature fluid checks were made each day instead of the standard two checks used in other wells in the formation.

While the 17½-in section was drilled, the OptiWell service detected high breakover torque and alerted operator. The alert included a recommendation to circulate at the highest allowable flow rate and to suspend cuttings above the BHA to alleviate hole cleaning problems. The alert indicated that two standpipes after the alert had lower breakover torque readings. While the 8½-in section was being drilled, the OptiWell service and PRESSPRO RT software measured standpipe pressure compared with modeled pressure measurements to detect a change in pressure due to plugged bit nozzles. Virtual hydraulics showed that it was likely that two nozzles were plugged. This was validated when the bit was pulled out of the hole showing two nozzles were indeed plugged.

The drilling plan included a step to circulate the bottom up at 100 rpm at the 17½-in section. This rpm did not provide sufficient hole cleaning, so the circulation was increased to 120 rpm and successfully cleaned the hole. The simple solution saved hours of rig time and is now a standard procedure for future drill plans.