Journal of Canadian Petroleum Technology
Volume 50, Number 2, February 2011, pp. 56-71

SPE-145158-PA

Experimental Study of Controlled Gravity Drainage in Fractured Porous Media

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DOI  More information 10.2118/145158-PA http://dx.doi.org/10.2118/145158-PA

Citation

  • Zendehboudi, S. and Chatzis, I. 2011. Experimental Study of Controlled Gravity Drainage in Fractured Porous Media. J Can Pet Technol  50 (2): 56-71. SPE-145158-PA. doi: 10.2118/145158-PA.

Discipline Categories

  • 6.3.1 Flow in Porous Media
  • 6.10.2 Naturally-Fractured Reservoirs

Keywords

  • controlled gravity drainage, critical production rate, liquid levels in fracture and matrix, recovery factor, fractured porous media

Summary

Oil production from a fractured reservoir with a gas cap and an oil zone usually takes place at a constant withdrawal rate until gas breakthrough; thereafter, the pumping rate is influenced by the presence of gas. Knowing the effect of pumping rate on production performance before gas breakthrough and selecting optimum pumping rates are necessary. In this paper, the concept of "critical production rate" (CPR) is introduced; it is the production rate at which a porous medium has a recovery factor (RF) equal to that for higher rates before gas enters into the production well, and is also the rate above which the difference between liquid levels in the fracture and matrix remains unchanged. One may use the CPR to choose a lower pumping rate to increase RF before gas breakthrough and to aid in understanding the physics of pumping from fractured media in real cases.

Flow visualization experiments were performed using rectangular unconsolidated-packed models with two fractures on the sides. Sensitivity analyses were performed on the effect of different system parameters on the CPR, the maximum possible withdrawal rate (MPWR), RF at gas breakthrough, and gas-liquid (G-L) interface behaviour in both matrix and fractures. Results show that as long as the porous medium is drained with a constant liquid withdrawal rate below CPR, the height difference between G-L interfaces in the matrix and fracture remains constant. CPR and RF can also be related to other system parameters using dimensionless numbers, such as fracture/matrix permeability ratio and Bond number.

© 2011. Society of Petroleum Engineers

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History

  • Original manuscript received: 16 June 2010
  • Meeting paper published: 8 June 2010
  • Revised manuscript received: 8 September 2010
  • Manuscript approved: 15 September 2010