OPERATOR’S CHALLENGE – Cantarell-2119 heavy oil well is located offshore Mexico, water depth 46 m (150 feet), in a block bounded by faults on both the east and west, presenting challenges that include total lost circulation zones and rock with high compressive strength averaging about 35,000 to 40,000 psi. There is high risk for differential sticking, borehole instability and pack-off conditions that can result in high non-productive time (NPT), loss of geological targets and higher costs. The challenge was to optimize the drilling performance throughout the well.