Utilizing Early Time Boundary-Dominated Flow Data to Make an Initial Estimate of Gas-in-Place: An Aid to Computing Material Balance Pseudotime

Abstract We investigate, through a graphical representation of dimensionless pseudocumulative function, the possibility of using only the early time boundary-dominated flow (BDF) data to make an initial estimate of gas-in-place. In particular, we demonstrate that when viscosity-compressibility product ratio is plotted against fractional recovery on linear coordinates, an early straight line is observed during BDF regime. This phenomenon permits the dimensionless pseudocumulative function to be expressed as a quadratic function which, upon approximation, yields a linear function in terms of fractional recovery. This work thus demonstrates that the utilization of actual cumulative in gas flowing material balance yields two negative slopes − early time and late time BDF lines. As opposed to the late time BDF line, the early time BDF line yields a reasonable initial gas-in-place, and thus considerably reduces the number of time-consuming iterations associated with computing material balance pseudotime function. Perhaps, the significant finding of this work is that it establishes that the approximate gas flowing material balance equation is strictly applicable to the early time BDF data. Simulated and field data for both single- and multi-well systems are presented to demonstrate the applicability of the proposed approach.