Modelling of Time-Dependent Wellbore Collapse in Hard Brittle Shale Formation under Underbalanced Drilling Condition

Table 1

Mineral composition of shale.

Well	Depth (m)	Percentage of minerals (%)
		Clay minerals	Quartz	Calcite	Plagioclase	Orthoclase	Dolomite
W-81	4900.01	43.06	39.94	1.71	12.21	0.00	3.08
W-82	4149.86	25.33	6.71	38.98	0.00	12.73	16.25
W-96	3901.10	19.09	36.45	9.07	27.54	6.42	1.44