Planning lessens problems, gets benefits of underbalance

A horizontal well planned to be drilled underbalanced required special procedures and countermeasures to prevent formation damage from the mud and downhole tool failures from high temperature. Drilling the well underbalanced helped reduce problems from lost returns and from solids entering and plugging the natural fractures in the Austin chalk. The high bottom hole temperature in the deep Austin chalk in central Louisiana complicates drilling, the mud program, and well design. The first of this two-part series covers the planning, procedures, and well design to alleviate these problems. The next article, which will appear in a future issue, addresses complications during the operation and the equipment used.