Development, testing, and application of a multi-well numerical coal seam degasification simulator
A series of mathematical formulations and numerical developments equipped with finite-difference approximation to simulate the simultaneous flow of gas and water in a coal seam and a tight gas formation is presented. The simulator employs a multi-dimensional, multi-phase formulation in rectangular coordinates and has options to accommodate a number of vertical wells as well as horizontal wells. For the vertical wells the model is able to handle the simulation of post-fracture performance through either horizontally or vertically fractured wells. Mining activity is also included to investigate methane emission at the mine working faces. Furthermore, options exist to include a number of impermeable geological barriers within the system. The transport of gas in coal seams can be formulated using a dual transport approach. In this approach, flow through macropores can be modeled with Darcy's law through the pressure field whereas flow through micropores can be modeled with Fick's law of diffusion through the concentration field. The combination of these two transport mechanisms extends the application range of these models to tight gas sand reservoirs. This is achieved by the exclusion of the kinetic sorption model. This quasi-steady state kinetic sorption model is included to represent the desorption of methane from coal grains. The developed numerical model has been tested and verified by using hypothetical reservoirs with increasing degrees of complexity and by history matching against the actual field data. Also, performance of the unconventional gas reservoir models has been compared against the performance of conventional gas reservoir models.
- Research Organization:
- Pennsylvania State Univ., University Park (USA)
- OSTI ID:
- 6379192
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
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03 NATURAL GAS
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Plowshare-- (-1989)
ALKANES
ANALOG SYSTEMS
COAL DEPOSITS
COAL SEAMS
COMMINUTION
DARCY LAW
DEGASSING
DIFFUSION
EMISSION
EQUATIONS
FINITE DIFFERENCE METHOD
FLUID FLOW
FRACTURED RESERVOIRS
FRACTURING
FUNCTIONAL MODELS
GAS FLOW
GEOLOGIC DEPOSITS
HYDROCARBONS
HYDROGEN COMPOUNDS
ITERATIVE METHODS
KINETIC EQUATIONS
LIQUID FLOW
MANY-DIMENSIONAL CALCULATIONS
MATHEMATICAL MODELS
METHANE
MINERAL RESOURCES
MINING
MULTIPHASE FLOW
NATURAL GAS WELLS
NUMERICAL SOLUTION
ORGANIC COMPOUNDS
OXYGEN COMPOUNDS
PERMEABILITY
POROSITY
RESOURCES
ROCKS
SANDSTONES
SEDIMENTARY ROCKS
SIMULATORS
TESTING
USES
WATER
WELLS
WORKING FACES