I'm not sure that's quite right regarding mud losses Mud is weighted to suit the formation and is affected by rig activities such as mud pump pressure, ROP, lifting of cuttings etc. It's a balancing act to try and remain neutral so as to not fracture the formation but also to prevent the formation releasing into the mud (a kick). I think most companies go slightly overbalanced to prevent kicks. Loss of mud / circulation is more likely to be because they are filling up cavern type hollows in the formation but there are other reasons such as passing through sands and other permeable zones. It's a common occurrence and can swallow up large quantities of mud and sometimes requires more drastic action to prevent losses There's nothing good about it and it's expensive with regards to mud but it's often part and parcel of drilling. I've been on jobs where boatloads of mud have had to be transferred across to make up the losses as well as running "pills" to bung up the loss zones I think the high pressure you mention is more to do with high pressure at the drill bit causing fracturing - the pressurised mud exits at the drill bit, there is "weight down" at the drill bit and factors such as the mud viscosity and importantly rate of turns of the drill bit can all contribute to high pressures that can cause fractures and losses to the formation
IVZ Price at posting:
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