|
 The Impact of Non-Darcy Flow on Production from Hydraulically Fractured Gas Wells
P. Handren, SPE, CARBO Ceramics Inc; C.M. Pearson, SPE, CARBO
Ceramics Inc; J. Kullman, SPE, CARBO Ceramics Inc; R. J. Coleman,
SPE, Chevron USA Production Co; J. Foreman, SPE, Halliburton
Energy Services; K. Froebel, SPE, Total-Fina-Elf; J. Caron, SPE, Total-Fina-Elf.
This paper summarizes the results of field trials performed to test the validity of the multiphase flow and non-Darcy correlations found in SLFrac (Stim-Lab’s Production Model). The case studies were done in two different gas fields – one in South Texas (Frio & Vicksburg reservoirs) and a second in the Green River Basin, Wyoming (Frontier & Bear River formation). A total of 17 fracture treatments were performed on 9 new wells (4 in South Texas and 5 in Wyoming). All treatments were designed to increase fracture conductivity to accommodate the effects of multiphase flow and non-Darcy flow. Results are compared to existing offset wells (which were treated with resin coated sand) to determine the production increase and evaluate the reliability of the model prediction.
In the Vicksburg wells (65 ft net pay, 0.1-1.0 md and 6000-8000 psi reservoir pressure), the actual IP matched the predicted IP, but only when accounting for the effects of multiphase and non-Darcy flow. Wells receiving CARBOECONOPROP® averaged 7 MMCFD, compared to model predictions of 5.1 MMCFD for wells receiving RCS.
For the Green River wells (50-200 ft net pay and 0.01-0.2 md), IP rates were grossly overestimated (200% high) when using the Darcy model, yet were within 10% of actual IP when accounting for multiphase and non-Darcy flow, even in wells with gas rates as low as 1 MMCFD. The paper concludes that first year average recovery improved by 93 MMCF or 34% over the previous set of wells. Surface restraints actually limited the "unexpectedly" high production rates. Had these restraints not been in place, the paper indicates that the incremental investment for CARBOECONOPROP® would have paid out in less than 20 days. |
