The Controls of Pore-Throat Structure on Fluid Performance in Tight Clastic Rock Reservoir: A Case from the Upper Triassic of Chang 7 Member, Ordos Basin, China

Table 1

The data of rate-controlled mercury injection (RMICP) and nuclear magnetic resonance (NMR) experiments and the corresponding helium porosity and air permeability of the samples from the Upper Triassic Chang 7 Member, Odors Basin.

Samples	Total mercury saturation (%)	Pore mercury saturation (%)	Throat mercury saturation (%)	Valid Throat volume in per unit of rock (mL/cm^3)	Threshold pressure (psi)	Threshold (maximum) throat radium (μm)	Average pore radius (μm)	Average throat radius (μm)	Average pore/throat ratio	Standard deviation coefficient of throat radii	Movable water saturation (%)	Valid porosity for movable water (%)	Irresistible water saturation (%)	Helium porosity (%)	Air permeability (×10^−3 μm^2)	ε
z-1	47.17	32.12	15.04	0.015	228.70	0.48	164.32	0.34	550.22	0.23	34.93	3.44	65.07	9.85	0.0102	4.36
z-2	46.70	31.07	15.63	0.016	274.08	0.40	162.46	0.29	657.51	0.25	30.03	3.09	69.97	10.28	0.0068	4.80
z-3	59.89	44.07	15.82	0.017	159.02	0.69	162.74	0.42	492.90	0.29	56.05	6.14	43.95	10.95	0.383	7.29
z-4	51.84	36.88	14.96	0.017	257.05	0.42	163.09	0.29	661.21	0.26	35.53	4.00	64.47	11.25	0.0134	5.76
z-5	52.93	40.01	12.92	0.015	258.08	0.42	166.38	0.28	691.16	0.26	37.40	4.22	62.60	11.29	0.014	6.02
z-6	56.85	40.69	16.16	0.019	191.84	0.57	159.81	0.35	559.51	0.28	47.38	5.42	52.62	11.45	0.018	6.96
z-7	49.00	29.62	19.38	0.015	203.06	0.54	163.40	0.27	522.29	0.35	/	/	/	7.58	0.106	4.83
z-8	35.96	18.48	17.48	0.026	292.23	0.37	153.80	0.28	602.90	0.22	/	/	/	14.77	0.012	5.55
z-9	44.94	32.50	12.44	0.019	280.55	0.39	163.60	0.26	764.21	0.28	/	/	/	14.95	0.016	8.56
z-10	37.61	20.94	16.67	0.017	167.23	0.65	159.36	0.47	418.75	0.32	/	/	/	10.31	0.139	5.89
z-11	32.90	13.43	19.47	0.012	203.31	0.54	162.29	0.32	405.12	0.25	/	/	/	6.32	0.041	2.43

Standard deviation coefficient, which was used to characterize the mathematic distribution of throat radius, was employed in this paper. The equation is as follows: , in which б is the standard deviation coefficient; is mathematic standard variation of throat radius; is the throat radius; is the average of throat radius; and is the proportion of corresponding throat radius. The combination parameter of pore-throat structure (ε) was calculated by the equation: , in which Ф is helium porosity; α is pore/throat ratio; is the percolation threshold (maximum) throat radius; б is standard deviation coefficient of throat radius. The physical meaning of ε is length (μm).