Advanced Flowing Material Balance To Determine Original Gas in Place of Shale Gas Considering Adsorption Hysteresis

A series of shale gas adsorption and desorption experiments are conducted. Desorption and adsorption curves are not coincident, with the former located above the latter, which suggests that adsorption hysteresis also occurs in shale gas. Pseudodeviation factor (Z*) is revised to advance the material-balance equation (MBE) and flowing material balance (FMB). The case study of the Fuling Shale in China illustrates that original gas in place (OGIP) of all three wells (1-HF, 2-HF, and 3-HF) calculated by conventional FMB is lower than that calculated by refined FMB, which has accounted for adsorption hysteresis. The conventional FMB underestimates OGIP of the three wells by 2.21, 3.29, and 4.02%, respectively. Adsorption hysteresis should be accounted for to accurately determine OGIP.