### Abstract

A solution package that describes the pressure transient behavior of coal reservoirs in the presence of a hydraulically fractured well is presented. In the development of the solutions uniform-flux vertical fracture model is employed. The proposed solutions are then extended to describe the pressure transient behavior of composite coalbed reservoirs with a vertical well which may have a vertical fracture. The proposed composite system solution has potential applications when ``Tailored-pulse'' fractures or damage exist around the degasification well. In this study, dual porosity nature of coal seams is modeled by describing micropore structure by spherical matrix elements. The formulation employed includes single-phase laminar gas transport in the natural fracture network (cleat system). Flow within the micropores is described by Fick's law of diffusion. Matrix to fissure flow mechanism is modeled by unsteady-state sorption/diffusion formulation. The equilibrium isotherm which defines the amount of desorbed gas is obtained through Langmuir's theory. The solutions are obtained analytically in the Laplacian space and inverted to the real time domain via Stehfest algorithm. The proposed solutions are tested against the subsets of the problem with known solutions and in each case excellent agreements are observed. Furthermore, the pressure transient data generated by a finite difference coal seam degasification model are used to check the validity of the solutions presented. Sensitivity of the solutions to a wide range of coal seam properties are also included. The solutions presented in this paper equip the well test analysis engineer with a precise tool to analyze the pressure transient behavior of the hydraulically fractured degasification wells. The solution package encompasses infinite, constant pressure and no-flow outer boundary conditions together with constant flow rate specification at the wellbore.

Original language | English (US) |
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Title of host publication | Formation Evaluation and Reservoir Geology |

Publisher | Publ by Soc of Petroleum Engineers of AIME |

Pages | 407-416 |

Number of pages | 10 |

Volume | Omega |

State | Published - 1992 |

Event | Proceedings of the 1992 SPE Annual Technical Conference and Exhibition - Washington, DC, USA Duration: Oct 4 1992 → Oct 7 1992 |

### Other

Other | Proceedings of the 1992 SPE Annual Technical Conference and Exhibition |
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City | Washington, DC, USA |

Period | 10/4/92 → 10/7/92 |

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### All Science Journal Classification (ASJC) codes

- Geology
- Geotechnical Engineering and Engineering Geology

### Cite this

*Formation Evaluation and Reservoir Geology*(Vol. Omega, pp. 407-416). Publ by Soc of Petroleum Engineers of AIME.