Oil & Gas Well Logging Essentials

A: That’s the most common mistake — confusing tool artifact with formation response. The difference matters because GR is formation-driven and shale-bound clays drive potassium and thorium signatures. ROP and mud stability remove several surface-driven explanations, so correlation against SP avoids chasing noise and prevents premature casing decisions.

A: That’s the most common mistake — focusing on CO2 because it’s easier to visualize. The difference matters because even low-percent H2S shifts failure toward cracking rather than wall loss, especially under residual stress from threaded connections. Temperature pushes kinetics, not mechanism.

A: That’s the most common mistake — treating neutron porosity as porosity rather than hydrogen density. The difference matters because gas reduces hydrogen per unit pore volume, so a higher apparent porosity demands an inflated index when back-calculated. A quick ratio against core porosity gets you there without software.

A: That’s the most common mistake — assuming formation change when only the invaded zone moved. The difference matters because deep resistivity anchors true Rt, and stopping the run loses continuity. Invasion effects are expected and correctable if you keep depth control tight.