Killing a highrate blowout well through a relief well
MetadataVis full innførsel
A kick can be defined as an unintended influx of formation fluids into a borehole. If the kick can’t be controlled it will evolve into a blowout. In this case a relief well would have to be drilled to stop the influx. To be able to kill the blowing well one need to increase the bottom hole pressure. When the bottom hole pressure in the well becomes greater than the reservoir pressure the influx is stopped. The method used to increase the bottom hole pressure is called dynamic kill. When drilling a relief well from a floater kill fluid is pumped from the relief well rig. The kill fluid goes down the kill and choke line through the BOP [Blow Out Preventer], into the annulus of the relief well, it continues further down the annulus to the intersect point and in to the blowing well. To be able to increase the BHP [Bottom Hole Pressure] one needs to deliver enough volume of mud at high enough pump rate. The blowing well will be stopped by pumping so fast that the pressure in the blowing well exceeds the formation pressure. When fluid is flowing in pipes it looses pressure; friction pressure. These friction pressure losses occurs in the pipes on the rig, in the kill and choke line and in annulus in both relief well and the blowing well. Different simulation tools has been used to run simulations to find out how the friction pressure is affected by water depth (length of kill and choke line), ID; [Internal Diameter] size on kill and choke line and mud-type used. These results are represented graphically. The water depth varied from 100m-1200m, ID on kill and choke line from 3” to 4,5” and mud weights varied from 1,8sg to 2,2sg. The only ID on kill and choke-line that were able to deliver required rate for all water depths and all mud types, without exceeding the pressure limitation for the rig where 4,5”. If the pressure exceeds the pressure limitations we need more than one relief well.
Master's thesis in Industrial economics