Analysis of a Hydraulically Fractured, Low Permeability Gas Reservoir Using Numerical Simulation

Bastian, P.A.; Sherman, J. B.

doi:10.2118/21511-pa

Cited by 3 publications

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References 8 publications

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“…The results shown in Figs. 7 and 8 are not new and are consistent with what we found in the literature, [9][10][11][12][13][14][15] namely that higher fracture conductivity promotes higher fracture fluid recovery and gas productivity. Long Fractures.…”

Section: Multiphase Resultssupporting

confidence: 89%

Effect of Fracture Conductivity on Effective Fracture Length

Lolon

McVay

Schubarth

2003

SPE Annual Technical Conference and Exhibition

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TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractFracturing fluid that remains in the fracture and formation after a hydraulic fracture treatment can decrease the productivity of a gas well by reducing the relative permeability to gas in the region invaded by this fluid. This fluid can block the gas flow into the fracture, thus reducing the effective fracture length. Pressure transient tests performed on hydraulically fractured wells often reveal that the effective fracture half-lengths are substantially less than the designed length from fracture stimulation.In this work we used reservoir simulation to determine the relationship between fracture fluid production, effective fracture length, and gas productivity. While the effective fracture length is affected by such factors as non-Darcy flow, it is related directly to fracture cleanup, and increases with time. From this study we found that the rate of fracture fluid production is affected significantly by the conductivity of the fracture. Greater dimensionless fracture conductivity results in more effective well cleanup, longer effective fracture lengths versus time, and greater effective stimulation of the well.The results of this study provide a better understanding of the gas production behavior from wells hydraulically fractured using water-based fracturing fluids.The relationships between fracture conductivity, effective fracture length, and gas productivity presented in this paper can be used in economic calculations to balance the costs of higher fracture conductivity against the additional revenue resulting from longer effective fracture lengths. Results presented will allow operators to better design optimal fracture lengths for typical gas reservoirs.

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Section: Multiphase Resultssupporting

confidence: 89%

Effect of Fracture Conductivity on Effective Fracture Length

Lolon

McVay

Schubarth

2003

SPE Annual Technical Conference and Exhibition

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Consideration of Damaged Zone in a Tight Gas Reservoir Model With a Hydraulically Fractured Well

Behr

Mtchedlishvili

Friedel

et al. 2006

SPE Production &Amp; Operations

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Summary This paper provides a detailed description of conditions in the hydraulically damaged fracture environment after closure and how to integrate them into a reservoir-simulation model. A special model-initialization algorithm was developed and realized in a support tool to make possible the computing of a post-fracture performance in tight gas formations by a reservoir simulator. The input represents the treatment schedule of the fracturing process and some results produced by commercial fracturing packages or geophysical measurements. To represent the fracture geometry and properties, the information about the distribution of the proppant concentration in the fracture as well as the fracture-width variation is translated into the permeabilities and porosities of the fracture gridblocks. To determine the fracturing-fluid saturation in the invaded zone, a new approach was derived to imitate the fracture propagation at a fracturing period under consideration of the leakoff processes. The penetration of the fracturing fluid into the matrix was modeled by the Buckley-Leverett equations for two-phase nonmiscible displacement, with boundary conditions provided by a classical leakoff theory. The approach is illustrated with a simulation model prepared for the analysis of the cleanup process in a damaged fractured well within a Rotliegende tight gas formation in north Germany. Introduction The fluid that leaked off into the tight gas formation during the fracturing treatment may significantly suppress gas production because of the two-phase flow effects and the capillary end effect between the reservoir and fracture (Holditch 1979). Therefore, for more plausible evaluation of hydraulic fracture stimulation, an accurate representation of the flow in the immediate fracture environment becomes a necessity. In terms of numerical simulation of post-fracture well performance, the problem can be addressed by (1) an adequate representation of the fracture in a reservoir simulator and (2) a reasonably accurate picture of the initial fluid distribution around the fracture.

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