RE: Flow rates, back in the groove10 Nov 2022 08:32
"Hi baits, the mud logger takes rock samples from the shakers to determine the drill depth as they proceed."
actually no - the wellsite geologist uses the samples to see what rock formation they are in and compares it to the prognosis. They know exactly where the drill bi is in x, y z from the amount of pipe in the hole and the directional drillers readout.
In a high angle/horizontal well like the sidetrack its really important to know where you are geologically - once you get near horizontal you risk drilling along just above the target and you can't execute a simple , immediate, turn down to hit the gas layer. Getting too deep isn't as bad but then you have to adjust the well so its drilling upwards at an angle - that leave the "heel " of the well lower than the formation and risks water coming in and cutting off production in the future while there is still a load of gas in the horizontal section.