Pressure testing data collected in Sebei-1 gas field are considered sufficient enough for calculating dynamic reserves of constant-volume gas reservoirs with pressure-drop method.By using the P/Z and G

p

data acquired in different development stages in Sebei-1 gas field

three types of pressure-drop curves were mapped

including linear curve

late upward broken curve and late downward broken curve.The first type of curve indicates that reservoir poroperm characteristics are homogenous in the swept region and production is stable.While reperforation may generate the second type of curve and boundary effects and inter-well interference may induce the third type of curve.Accordingly

dynamic reserves can be calculated through extrapolating the straight pressure line until P/Z equals to 0

while for the later two types of curves

the calculation may be performed by selecting the late section of straight line and extrapolating it.