PRESSURE-WHILE-DRILLING DATA IMPROVE RESERVOIR DRILLING PERFORMANCE

A new downhole annular pressure-while-drilling (PWD) tool has been app lied recently to assist in drilling the reservoir section on the Statf jord field, offshore Norway. For drilling success in these high-angle wells it is critical to maintain the mud weight and equivalent circula ting density (ECD) within safe operating limits defined by the formati on fluid, collapse, and fracture pressures. Operating outside these li mits historically has led to expensive lost circulation, differential sticking, and packoff incidents. Monitoring the actual downhole pressu re in real time with a PWD tool, rather than relying on inferred press ures from predictive models, has allowed the operator to stay within a nd to better define these operating limits. The operator used this imp roved hydraulics information to avoid pressure-related hole problems, to optimize drilling practices, to test hydraulics models, and to obta in a greater understanding of the formation pressure limits.