This report presents an overview of the kill resource requirements for controlling potential blowouts from the Alpha and Beta structures developed by the Offshore Operating Company.
The scenarios studied were - drilling into top reservoir zones before setting 9-7/8 inch casing with zones partially penetrated as well as flow from all zones through 9-7/8 and 10 ¾ inch casing unrestricted to surface.
The kill requirements for snubbing kill assuming a new pipe can be snubbed into a well flowing underground were also investigated. Snubbing kill can be an option for some scenarios, and in particular in combination with relief well kill. This is also an option, which should be investigated further if a gunk material kill should be used.
The report focuses on blowout and well kill simulations. The resource requirements in terms of pumping rate, pressure, power and volumes, as well as relief well casing are given.
The objectives of this blowout contingency plan are:
To provide a technology check on blowout control feasibility
Identify resource requirements for blowout control operations
Calculate maximum potential blowout and kill rates
The main conclusions of the study may be summarised as follows:
All scenarios show very high gas outflow rates with maximum at 620 MMscfd.
Blowouts from these high productive gas reservoirs will be very difficult to kill, and may necessitate the drilling of two relief wells.
Snubbing kill is not possible if the underground blowout occurs before the 9-7/8 inch casing as set under the conditions studied.
Kill rates are potentially high with high pumping requirements.
For actual blowouts, extra restrictions, such as broken pipe, fishes and other downhole restrictions, or a partially closed wellhead or BOP are often present in the flow path. The results presented in this report make no allowance for a partially plugged flowpath and do represent "worst case" scenarios.