East Texas 2005

Problem: A vertical exploration well in Harris County Texas was drilled to asses commercial hydrocarbon potential of the Yegua and K1/Cochran sand packages. While drilling 9-7/8 hole at a depth of 11,137 ft a kick was taken. While circulating the kill mud the well started leaking at the Braden head flange. The well blewout and caught fire shortly after. The well was initially flowing gas, saltwater and sand to the surface from drillpipe and cellar. Subsequent, the gas started broaching around the location both inside and outside the levee area. After appearing to have bridged and then proceeding to flow again several times, the fire went out and the well remained dead. However, several potential underground crossflow scenarios still existed.
Remedial Strategy: The initial plan selected was to first diagnose the potential underground crossflow scenarios prior to attempting control operations. The relief well would be drilled through the Vicksburg formation parallel and close proximity of the target well to check for crossflow into this formation. Subsequent, if no crossflow to the Vicksburg was identified, a temperature and noise log would be run to check for flow to shallower zones. Any flow would be hydraulically killed by injecting kill mud from the relief well into the blowout flowpath. After bringing the target well to static conditions, the blowout borehole and drillstring would be satisfactorily plugged and abandoned as required by the Texas Railroad Commission. Finally, as a secondary objective, the relief well would be drilled as a replacement well where it could reassess the commercial hydrocarbon potential.
Special Services: John Wright Company was contracted to provide both strategic and tactical special services. JWCO supervised the special services required for the relief well intervention project. This included pre-planning and on-site supervision of directional drilling, surveying, kill operations and casing detection. Vector Magnetics, responsible for electromagnetic ranging, was coordinated through JWCO on this project and worked together as one team. Well Flow Dynamics was instrumental in the diagnostic investigation and in simulating various kill scenarios for possible kill operations.  Alert Disaster Control (US), Inc.  acted as the general contractor.

Challenges Met:  The project was complicated by the following:

  • Well located in a residential area close to Houston Texas
  • High initial media exposure
  • Only low accuracy inclination-only surveys existed for the target well
  • Over 8000-ft of open hole exposed to unconsolidated formation 
  • Potentially shallow supercharged zones
  • Several sands that could be flowing or be potential recipients to cross flows
Results:
  • The relief well located the target well at 6291 ft MD 57 +- 7 ft away.
  • The relief well was drilled parallel to the target well through the Vicksburg formation.
  • No significant gas was measured in the Vicksburg formation and no flow was observed in the target well using noise and temperature logs.
  • The relief well was plugged back to the 9-5/8 shoe and a new section was kicked off to intersect the target well above the Vicksburg without annular mud loss.
  • Communication with the target drillpipe was achieved by milling a notch at 8473 ft
  • The target well was cemented  to the satisfaction of the Texas Railroad Commission.