Chapter 11 Relief Well Engineering to Control Blowouts

Abstract

The most efficient way to control a blowout is to drill one or several relief wells that reach the wild or uncontrolled well, above or at the producing problem formation. This chapter describes flowrate estimates, control techniques, trajectory planning, relief well directional surveying, and distance ranging techniques. The chapter also presents and discusses several examples of typical blowouts related to overpressure. Relief well drilling is mandatory when a deep blowout occurs because there is no guarantee that the well will bridge and the blowout will die. Even if bridging does occur, an underground blowout may still be in progress. In any well, a reliable borehole trajectory survey should be made, when high-pressure zones are suspected and a blowout is possible. This strategy prevents long and costly ranging operation to locate the blowout well. Measurement-while-drilling (MWD) techniques provide excellent trajectory control of the relief well, allowing the target to be reached precisely and efficiently.