Publications

Static material balance (P/Z method) is often used to estimate gas initially in place (GIIP) for the reservoir management purpose. The P/Z method at an early stage of development provides minimum connected gas volume detected by production wells, requiring well shut-in to obtain average reservoir pressure. Dynamic material balance method, relatively recent advent, aims at the same objective but directly uses continuous production data under the assumption of the boundary-dominated flow. The method does not require well shut-in and thus saves loss of production. There exists several dynamic material balance equations proposed in the literatures, however none of them has a capability to accurately estimate GIIP under the non-Darcy effect (rate dependent skin). In this paper, we formulate one dynamic material balance equation to effectively account for the non-Darcy effect and demonstrate the accuracy enhancement through several case examples.