West Texas 1992

Problem: A workover resulted in an unintentional sidetrack through the existing casing of this production well. Junk in the hole made it impossible to re-enter the well below the sidetrack utilizing conventional methods. Perforations in the lower section of the production casing were open to an over pressured reservoir in this waterflood area of the field. A cross flow situation and charging of shallower zones resulted and caused concern for field production, environmental implications and subsequent drilling operations. Several unsuccessful and very costly attempts to plug the well utilizing conventional methods and techniques were tried.
Remedial Strategy: The flowing well would have to be plugged by unconventional techniques. The remedial operation, utilizing the existing wellhead, was planned to intersect the existing production casing in several intervals. After setting of casing on the remedial wellpath hole, a perforating operation would establish hydraulic communication for a final plug and abandonment of the well. The remedial path would begin at a sidetrack plug set atop the corroded casing stub. Very close proximity to the target wellpath was critical to allowing selective perforating to seal off water zones.
Special Services: John Wright Company (JWCO) was contracted to supervise the special services. This would include pre-planning and on-site supervision of: directional drilling, surveying, casing detection and perforating. Vector Magnetics provided electromagnetic ranging services and worked together with JWCO to create a single team.
Challenges: The project was complicated by the following:
  • There were no borehole surveys of any kind on the flowing well.
  • Casing had to be milled out of the conductor to provide adequate hole size.
  • Shallow charging required an intermediate string to be set to seal that zone.
  • Condition of the casing string was suspect and flow was expected when close.
  • Drilling parallel and alongside existing casing without surveys would require precise directional control and accurate casing detection techniques.
Results:
  • Team concept for special services was successfully and efficiently utilized.
  • Existing wellhead was successfully utilized for the remedial well.
  • Surface excitation and electromagnetic ranging techniques were successful.
  • A rate gyro was successfully used to orient drill with less than 1 inclination.
  • Remedial well placement to within 6" proximity over long intervals achieved.
  • Communication was achieved over two intervals with oriented perforating guns.
  • Cement was squeezed into two perforated zones with a cement plug on top.
  • The Texas Railroad Commission approved the P & A project as implemented.