Re : Drilling experts27 May 2019 09:42
Well, I for one gave up drilling a lifetime ago now ( about 20years) and since I last got on the chopper home I have had just about no involvement or particular interest in it, however, the overall process hasn't changed, only some of technology and the ability to better interpret what is happening down hole through electronic and better seismic data. Ddboy mentioned a mud motor, I didn't comment, but just my opinion is that it would be unlikely unless this is a directional drill and tbh, I don't know or particularly care whether it is or not. Yep, I know they can be used in verticals and in theory increase the rop whilst slowing down the rpm of th string, but I still doubt there being any need. This cement job using the thing I called a cement mixer that someone jumped down my throat about saying they done use cement mixers, will be mixing cement on site using the hopper that is clearly visible on the back of the truck and then adding various chemicals such as ******er to slow down the hardening process and allow the cement to flow behind the casing. They will have to get rid of any mud gels by circulating th mud out for some time until they are reasonably sure that here are no lumps of mud left that would give problems to the cement slurry. E.g., mud going in at the top is the same as the mud coming back into the pits or tank or whatever they have. Same shear forces, same viscosity etc which indicates that there is a free flow from the dap up the outside of the casing. They will pump the cement in to the calculated volume necessary to reach the right depth which should be an hour or two's work and then leave it to reach the desired strength before drilling. They may send a skinny bloke with long arms into the hole to tap the inside of the casing to check for any hollow sections behind the casing, or they may run an ultrasonic log to do the same job, or they may just be satisfied running a bench test with a simulation of downhole temp and pressure on a 'test piece' to check its strength and the assume the same has happened down hole. Hopefully th casing will have been run with centralisers to pr vent it from jamming against one side or the other of the well bore and to disrupt the cement flow and create some turbulence to enable the cement to reach all the way around and into any little anomalies in the formation. We dont want any gas finding its way up the outside of the casing and onto the drill floor do we now. Keep the pipe turning during the cement process to help cement flow or use a reciprocal motion using the drawworks but personally I'm not keen on that method as it causes pressure differentials down hole and well damage. Anyhow, after the cement has set, that cement mixer can drive off and they can drill through the cement plug and press on for another 600m or thereabouts. ATB retired ( from drilling) non expert. Last post here, not interested in ego's, or justifying my existence.