Pressure transient analysis for fluid flow through horizontal fractures in shallow organic compound reservoir of hydrogen and carbon

Abstract

Pure hydrogen does not occur in large quantities in nature, and it is usually locked up in energy-rich organic compound. One of the challenges to sustain the usage of hydrogen energy is to produce sufficient energy-rich organic compound from the organic compound reservoir of hydrogen and carbon, which requires understanding the fluid flow behavior through such reservoir. The horizontal fractures can be created during the hydraulic fracturing process in shallow energy-rich organic compound reservoirs due to the geo-mechanical effect. However, it lacks of a comprehensive analytical model to describe the transient flow behavior through the horizontal fractures. In this paper, an analytical model for horizontal fractures in shallow organic compound reservoirs considering the effects of wellbore storage and skin factor with constant pressure, closed and infinite boundary conditions, are presented to investigate pressure transient behavior and flow characteristics. The analytical solution is derived in Laplace domain, which may require numerical inverse transform to obtain the solution real space. To obtain the explicit form in real space, the approximate solutions for early time, middle time and late time are also presented to investigate the characteristics of type curves. Type curves are established for the transient pressure analysis to recognize the flow characteristics through horizontal fractures. Flow for horizontal fractures can be divided into five stages according to characteristics of dimensionless pseudo pressure derivative curve. The effects of parameters on pressure behavior are discussed in detail, which include wellbore storage coefficient, dimensionless formation thickness, dimensionless vertical location, and skin factor. The results indicate that horizontal fractures are more applicable in thin instead of thick reservoirs.