Design flexible system for varying pressure gradients, reduce drilling problems
This multi-well project was a deep, depleted, fractured and compartmentalized reservoir with widely variable pore pressures. The objective was to design a flexible system to cover pressure gradients from 2 to 8.34 ppg, minimizing overbalance because of the narrow margin between pore and fracture pressures, and to reduce drilling problems of differential sticking and lost circulation.
The operator controlled bottomhole pressure (BHP) through precise selection of critical operating parameters such as injection flow rates, fluid properties and chemical injection control. Utilizing Sperry Drilling Services’ GeoBalance™ Managed Pressure Drilling (MPD) service, the operator was able to measure, record and display important variables at the rigsite and transmit them to other locations, allowing remote monitoring and real-time adjustments to maintain the narrow target range for BHP.
Days average cleanup time
Days less clean-up time
Successful implementation of MPD in this case resulted in 1) process improvements from lessons learned while drilling challenging hole sections under changing conditions, and 2) increased rate of penetration (ROP) despite controlled drilling for hole cleaning. MPD times were approximately half those of offset conventional overbalanced drilling (OBD) wells. And when the MPD wells were brought on for production, cleanup times fell from 20 days to an average of three days.