Discrete Element Analysis for Hydraulic Fracture Propagations in Laminated Reservoirs with Complex Initial Joint Properties

Table 3

Number of each fracture type with different joint strengths.

Joint strength (strength ratio to the base)	Approach angle	Sjs	Sjt	Pbs	Pbt	Sum
(0.8 : 1)	30°	263	48	158	266	735
	45°	308	22	180	237	747
	60°	361	9	154	186	710
	75°	237	1	114	145	497
	90°	172	6	93	134	405
(set as a base)	30°	147	13	134	286	580
	45°	256	11	185	308	760
	60°	292	12	126	235	665
	75°	178	4	114	150	446
	90°	42	0	85	137	264
(1.2 : 1)	30°	77	17	125	242	461
	45°	57	7	113	266	443
	60°	126	1	102	211	440
	75°	107	2	93	160	362
	90°	8	0	85	140	233

Notes. Sjs represents shear failure of bedding planes. Sjt represents tensile failure of bedding planes. Pbs represents shear failure of the shale matrix. Pbt represents tensile failure of the shale matrix.