List of top Oil and Gas Well Drilling Technology Questions

The hydrostatic pressure gradient in a vertical well drilled in a relaxed depositional basin is 0.452 psi/ft. Assume that the gradient of effective horizontal stress with depth is constant in the drilling zone and has a value of 9.96 × 10⁻² psi/ft. The casing shoe is at 4000 ft depth.
While drilling the bore hole below the casing shoe with 10 ppg mud, the maximum allowed standpipe pressure is .......... psi (rounded off to one decimal place).

A vertical well is drilled up to a depth of 4000 ft. Further drilling starts with 10 ppg of fresh mud and 50000 lbf weight on bit (WOB). An equivalent circulation density (ECD) of 10.75 ppg was recorded. The total circulation pressure loss is estimated to be 110 psi. The still density is 65.5 ppg.
The decrease in hook load is .......... lbf (rounded off to one decimal place).

A drilling fluid with time-dependent rheology is used for the rotary drilling of a reservoir. The following equation describes the dependence of shear stress (\( \tau \)) on shear rate (\( \dot{\gamma} \)):
\[ \tau + \frac{\mu_0}{\alpha} \frac{d\tau}{dt} = \mu_0 \dot{\gamma} \] where \( \mu_0 \) and \( \alpha \) are constants.
If the rotation of the drill pipe is stopped at time \( t = 0 \), then the relaxation behavior of the fluid stress with time is:

The hoisting system of a drilling rig contains seven ideal sheaves with hook load of \( 3.0 \times 10^5 \) kg. The static derrick load is .......... × \( 10^5 \) kg (rounded off to one decimal place).