Real-time Wellbore Stability Analysis: An Observation from Cavings at Shale Shakers*

Drill cuttings are considered representative of the lithology being drilled in a wellbore. However, the fragments that are two to three times larger and/or having odd shapes compared to the regular cuttings are commonly understood as cavings from the wall of the borehole and they are seldom of any help in compilation of a lithology. In fact, cutting description manual recommends ignoring cutting sizes greater than half an inch. Nevertheless, these cavings carry critical information that needs expert decoding concerning impending or happening wellbore instability, formation overpressure and overall well behavior evaluation.