SPE Journal
Volume 17, Number 1, March 2012, pp. 230-242

SPE-144317-PA

Production Analysis of Tight-Gas and Shale-Gas Reservoirs Using the Dynamic-Slippage Concept

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DOI  More information 10.2118/144317-PA http://dx.doi.org/10.2118/144317-PA

Citation

  • Clarkson, C.R., Nobakht, M., Kaviani, D., and Ertekin, T. 2012. Production Analysis of Tight-Gas and Shale-Gas Reservoirs Using the Dynamic-Slippage Concept. SPE J.  17 (1): 230-242. SPE-144317-PA. http://dx.doi.org/10.2118/144317-PA.

Discipline Categories

  • 6.9 Unconventional Hydrocarbon Recovery
  • 6.9.2 Shale Gas
  • 6.9.3 Tight Gas
  • 6.5.1 Simulator Development
  • 6.3.1 Flow in Porous Media

Keywords

  • Shale Gas, Tight Gas, Rate-Transient Analysis, Dynamic-Slippage

Summary

Shales and some tight-gas reservoirs have complex, multimodal pore-size distributions, including pore sizes in the nanopore range, causing gas to be transported by multiple flow mechanisms through the pore structure. Ertekin et al. (1986) developed a method to account for dual-mechanism (pressure- and concentration-driven) flow for tight formations that incorporated an apparent Klinkenberg gas-slippage factor that is not a constant, which is commonly assumed for tight gas reservoirs. In this work, we extend the dynamic-slippage concept to shale-gas reservoirs, for which it is postulated that multimechanism flow can occur. Inspired by recent studies that have demonstrated the complex pore structure of shale-gas reservoirs, which may include nanoporosity in kerogen, we first develop a numerical model that accounts for multimechanism flow in the inorganic- and organic-matter framework using the dynamic-slippage concept. In this formulation, unsteady-state desorption of gas from the kerogen is accounted for. We then generate a series of production forecasts using the numerical model to demonstrate the consequences of not rigorously accounting for multimechanism flow in tight formations. Finally, we modify modern rate-transient methods by altering pseudovariables to include dynamic-slippage and desorption effects and demonstrate the utility of this approach with simulated and field cases. The primary contribution of this work is therefore the demonstration of the use of modern rate-transient methods for reservoirs exhibiting multimechanism (non-Darcy) flow. The approach is considered to be useful for analysis of production data from shale-gas and tight-gas formations because it captures the physics of flow in such formations realistically.

© 2012. Society of Petroleum Engineers

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History

  • Original manuscript received: 14 March 2011
  • Meeting paper published: 12 June 2011
  • Revised manuscript received: 28 June 2011
  • Manuscript approved: 7 July 2011
  • Published online: 8 February 2012
  • Version of record: 13 March 2012