Abstract
Continuous developments in oil and gas drilling operations have resulted in a significant increase in the application of extended reach wells sometimes combined with HP/HT down-hole conditions.
HP/HT conditions are generally taken into account as key inputs for directional drilling equipment and casing and tubing strings selection. Indeed, high downhole pressures and temperatures limit the selection of materials for these equipments and also drive their design properties.
Concerning tubulars, casing and tubing strings designed for HP/HT wells incorporate heavier body walls, high grades and special premium connections to withstand pressure levels associated with high to extreme tension or compression.
Recent drilling operations in the North Sea have shown that drill string tubulars can also be impacted by the combination of high levels of torque & drag associated with ERD and high temperatures. Not anticipating the effect of such combinations in the well planning and drill string selection phases can result into severe operational issues.
This paper describes the lessons learned during recent extended reach drilling operations with HP/HT downhole conditions and presents the key factors to be considered for appropriate drill string specification and field running in such cases.
