You have the following production data for a gas field that might be produced by a natural water drive. Pressure Bg (106 scf) (MPa) (rb/scf) 0 40 0.0018 58 38 0.0022 113 36 0.0029 143 34 0.0035 167 32 0.0042 The initial water saturation is 0.27 and the residual gas saturation, from laboratory measurements, is 0.34. The material balance equation is: B gi = 1 B g W + B e g Assuming a simple aquifer model, plot a graph and use this to make an approximate estimate of the original gas in place and the value of the aquifer size times the aquifer compressibility. You may neglect the compressibility of the connate water and rock in the gas field itself. (18 marks)