Stress-Induced Permeability Reduction in Fissured Reservoirs

Abstract

Stress-Induced Permeability Reduction in Fissured Reservoirs Hubert Buchsteiner; Hubert Buchsteiner Mining U. Leoben Search for other works by this author on: This Site Google Scholar N.R. Warpinski; N.R. Warpinski Sandia Natl. Laboratories Search for other works by this author on: This Site Google Scholar M.J. Economides M.J. Economides Mining U. Leoben Search for other works by this author on: This Site Google Scholar Paper presented at the SPE Annual Technical Conference and Exhibition, Houston, Texas, October 1993. Paper Number: SPE-26513-MS https://doi.org/10.2118/26513-MS Published: October 03 1993 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Get Permissions Search Site Citation Buchsteiner, Hubert, Warpinski, N.R., and M.J. Economides. "Stress-Induced Permeability Reduction in Fissured Reservoirs." Paper presented at the SPE Annual Technical Conference and Exhibition, Houston, Texas, October 1993. doi: https://doi.org/10.2118/26513-MS Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAll ProceedingsSociety of Petroleum Engineers (SPE)SPE Annual Technical Conference and Exhibition Search Advanced Search AbstractStresses near any wellbore are different and likely to be higher than the far-field stresses. In addition, fluid production and the corresponding pressure drawdown lead to an increase of the effective stress. This increase results in a substantial reduction in the corresponding permeability, especially if the latter is primarily due to natural fractures. The phenomenon may result in unequal reduction in the components of the permeability tensor, thus inducing permeability anisotropy and, in certain naturally anisotropic cases, may alter the direction of the maximum and minimum permeabilities. A model, relating effective stress and permeability / permeability anisotropy has been employed to study the expected well performance and implications on hydraulic fracturing. The effect of the permeability alteration ranges from moderate to severe and appropriate reservoir exploitation must consider these phenomena.IntroductionThe reservoir permeability, perhaps the most important property governing reservoir performance, is a vector with often considerable anisotropy. This anisotropy, while always important in relatively homogeneous reservoirs completed with vertical wells, it is somewhat forgiving, affecting mainly long-term strategies. Muskat has shown, in what is considered to be a classic work, how the permeability tensor is related to the system permeability value, controlling inflow in vertical wells.Permeability anisotropy, though, becomes crucial when linear features such as hydraulic fractures (which have a preferred direction) or horizontal wells (which can be drilled in an arbitrary direction) are introduced into the reservoir. Deimbacher et al. Mukherjee and Economides and Warpinski have shown the considerable effects of permeability anisotropy vs well direction on horizontal well performance. This issue becomes even more important when hydraulic fractures are executed in horizontal wells.The presence of fissures is critical to petroleum recovery and the fissure systems have often been found to be highly anisotropic. In many naturally fissured reservoirs these features are aligned with the maximum horizontal stress. Thus, a hydraulic fracture is likely to parallel instead of intersect natural fissures. Their heterogeneous distribution and resulting permeability anisotropy affects expected production from a hydraulic fracture that is normal to the lower permeability value. This would have an adverse effect on the post-treatment performance of a fracture, designed on the basis of a permeability value extracted from a pretreatment pressure transient test. Ben-Naceur and Economides have quantified an apparent (and smaller than actual) hydraulic fracture length in anisotropic formations. Attempts to hydraulically fracture naturally fissured formations have revealed not only a very complex hydraulic fracture behavior at geologic discontinuities, but also a highly stress-dependent permeability of natural fissures and effects on leakoff and formation damage.Identification and understanding of the characteristics of fissured reservoirs, or stress-sensitive reservoirs in general, is essential for economic production.P. 65^ Keywords: anisotropy, hydraulic fracture, flow in porous media, upstream oil & gas, natural fracture, pore pressure, effective stress, orientation, drillstem testing, fluid dynamics Subjects: Hydraulic Fracturing, Reservoir Fluid Dynamics, Formation Evaluation & Management, Unconventional and Complex Reservoirs, Flow in porous media, Drillstem/well testing, Naturally-fractured reservoirs This content is only available via PDF. 1993. Society of Petroleum Engineers You can access this article if you purchase or spend a download.