Core 11 12 13 14 14x 15 16 17 18 19 20 22 23 Several sandstone samples were used to investigate the rela- tionship between the formation resistivity factor and porosi- ty. Each sample is a cylindrical plug with d=2 cm and L ranging from 2.5 to 3.10 cm. These plugs were taken from a large-diameter core. The samples were cleaned, dried, and weighed. They were then fully saturated with a 50,000-ppm brine and reweighed; their resistances were also measured. In the weighing process, the sample was placed in a 13.04 g- cylindrical container to prevent the brine from evaporating. All measurements were conducted at 70F. The data collected are listed below. Length (cm) 3.05 3.05 3.05 3.00 3.10 3.05 3.05 3.05 3.05 3.00 3.05 3.00 2.80 Dry Core Weight 20.59 19.13 19.68 21.09 21.21 18.60 19.37 20.70 19.31 19.37 17.84 18.65 16.90 Saturated Core Weight Plus Bottle 34.64 33.53 33.99 34.84 35.04 33.03 33.62 34.64 33.68 33.64 32.58 33.25 31.40 To (12) 860 520 580 2,200 2,100 465 1,000 1,100 500 830 360 460 340 23x 24 26 3.00 2.50 3.00 18.01 13.44 15.72 32.57 27.96 31.01 370 210 200 a. Calculate the porosity and formation resistivity factor of each core. b. Plot vs. F on a 2x3 cycle log-log paper. c. Can these data be fitted satisfactorily by a relation of the form F=ap-2? If so, determine the value of the coeffi- cient a.