||Problem: Kick was taken
after drilling into the top of a pinnacle reef. Casing was set too shallow to shut the
well in and was put on diversion. In an attempt to cap the well from the surface the
drillpipe was subsequently dropped and a capping stack put in place for further snubbing
option and to divert the flow into an emergency separation unit. The flow was estimated at
+/- 20 MMscf/d gas, 700 BOPD and 3000 BWPD. The snubbing option was unsuccessful in
fishing the drillpipe in open hole.
|Remedial Strategy: The
blowout was put on diversion through an emergency separator and gas compression into a
sale line. Excess gas was flared. 4-1/2 casing was snubbed into 425 ft. A relief
well was spudded 298 ft from the original wellhead. The relief well would intersect the
blowout at the top of the pinnacle reef and would then be used to kill then P & A the
blowing well. The relief well would then be sidetracked and used as a replacement well.
See figure 1.
|Special Services: John Wright Company (JWCO) was contracted to supervise the special
services required for this project. Special services included pre-planning engineering and
on-site supervision of: directional drilling, surveying, casing detection and kill
operations. The field operator and drilling contractor supervised the normal drilling
activities. Vector Magnetics was contracted and was responsible for electromagnetic
ranging services, Well Flow Dynamics performed the kill hydraulic calculations, Boots
& Coots provide service control services and worked together with the JWCO on this
project as one team.
|Challenges: The project
was complicated by the following:
- There were no borehole directional surveys on the flowing
- Position uncertainty at TD was +/- 35 ft based on Totco
- Loss of circulation in the top of the pinnacle reef and
inability to circulate kill fluid.
- Team concept for special services was successfully and
- Electromagnetic ranging located the blowout fish as planned.
- Relief well intersected the top of the reef as planned.
- HCL was used to gain communication in the top of the reef.
- The well was killed using mud but no returns were observed
at the surface
- The blowout was then P & A with cement and turned back
to the operator.