|
 The Development of Laboratory Correlations Showing the Impact of Multiphase Flow, Fluid and Proppant Selection Upon Gas Well Productivity
Glenn S. Penny and Liang Jin, STIM-LAB, Inc.
TThis paper indicates that proppant conductivity values used in the industry are exceedingly optimistic. Conductivity is often reduced by a factor of 10 when the impact of time, temperature, and embedment are considered. Gel residue and other fluid damage may reduce the conductivity by an additional factor of 2 to 10. These adjustments are beginning to be considered during fracture design, but many engineers still fail to adjust for multiphase and non-Darcy flow.
The authors provide lab data showing drastic reductions in effective conductivity due to multiphase and non-Darcy flow. For a modest well, the conductivity is shown to be reduced by a factor of 17, without considering damage by fracturing fluids! Although it is preferable to measure the effects for each proppant at anticipated conditions, the authors supply general rules of thumb: The effective conductivity of the fracture is typically reduced by a factor of three for each MMCFD of gas at 2000 psi produced through a 50’ fracture propped with 2#/sq ft proppants. For each 4 blpd contained in each MMCFD, the effective conductivity is reduced by an incremental factor of 3. For a well producing 2 MMSCFD and 4 barrels of condensate or water at a bottomhole pressure of 2000psi, the effective conductivity is expected to be reduced by a factor of 27. Figure 12 in this paper shows the actual conductivity measured in the lab for three proppant types under laminar flow conditions, and realistic fluid velocities, showing discrepancies approaching 2000%!
“The results of the testing show that multiphase non-Darcy flow dramatically increases the difference between the effective conductivities of various proppants at high closures. The laboratory data and field observations show that when this is taken into account, a premium proppant can show twice the production rate of commonly used sand products at high closures in gas wells producing as little as 10 barrels of water or condensate per MMCF.”
|
