Oil Well Completions Concepts and Calculations Part 1

A: Governing principle: Hardware placement is executed in MD, but reservoir targets and zonal isolation intent are defined in TVD. Applied here: At 35° inclination, MD–TVD divergence is material; a quick cosine check validates whether 8,500 ft MD reasonably maps to ~7,900 ft TVD before accepting the tally. Distractor trap: Option A catches engineers who know MD drives running depth but forget the TVD objective can still be missed.

A: Governing principle: Hydrostatic pressure scales linearly with fluid gradient and true vertical depth. Applied here: 9.5 ppg gives ~0.433 × (9.5/8.34) ≈ 0.49 psi/ft; multiplied by 8,000 ft lands near 3,900 psi, making 3,600 psi the closest defensible estimate. Distractor trap: Option B tempts with a round gradient but drifts high when checked against actual brine density.

A: Governing principle: Collapse failure is governed by the maximum differential pressure across the pipe wall. Applied here: A kill with an empty or near-empty tubing string imposes hydrostatic external pressure with minimal internal support, the governing collapse scenario API intends to cover. Distractor trap: Option D appeals to those mixing axial and radial failure modes without checking which one governs collapse.

A: Governing principle: CO2 in the presence of free water drives carbonic acid corrosion in carbon steel. Applied here: Wet gas and chloride brine establish water wetting, making CO2 partial pressure the rate driver rather than sulfide mechanisms. Distractor trap: Option C catches teams over-weighting short-term oxygen exposure while ignoring sustained CO2 chemistry.