A New Correlation of Acid-Fracture Conductivity Subject to Closure Stress
- Jiayao Deng (Texas A&M University) | Jianye Mou (China University of Petroleum, Beijing) | Alfred D. Hill (Texas A&M University) | Ding Zhu (Texas A&M University)
- Document ID
- Society of Petroleum Engineers
- SPE Production & Operations
- Publication Date
- May 2012
- Document Type
- Journal Paper
- 158 - 169
- 2012. Society of Petroleum Engineers
- 3 Production and Well Operations, 3.2.4 Acidising, 4.3.4 Scale
- fracture conductivity, Acid Fracturing
- 8 in the last 30 days
- 1,258 since 2007
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The conductivity of an acid-etched fracture depends strongly on void spaces and channels along the fracture resulting from uneven acid etching of the fracture walls. In this study, we modeled the deformation of the rough fracture surfaces acidized in heterogeneous formations based on the synthetic permeability distributions and developed a new correlation to calculate the acid-etched fracture conductivity.
In our previous work, we modeled the dissolution of the fracture surfaces in formations having small-scale heterogeneities in permeability. The characterization of the correlated permeability fields of rock includes the average permeability, normalized correlation lengths in both horizontal and vertical directions, and normalized standard deviation. These statistical parameters have a significant influence on the fracture-etching profiles obtained from the model. Beginning with this fracture-width distribution, we have modeled the deformation of the fracture surfaces as closure stress is applied to the fracture. The elastic properties of the rock, such as Young's modulus and Poisson's ratio, have effects on the size of the spaces remaining open after fracture closure. After the model yields the width profile under closure stress, the overall conductivity of the fracture is then obtained by numerically modeling the flow through this heterogeneous system.
In this paper, we introduce our models and investigate the effects of permeability and mineralogy distributions and rock elastic properties on the overall conductivity of an acid-etched fracture. A new acid-fracture conductivity correlation is developed on the basis of many numerical experiments.
|File Size||4 MB||Number of Pages||12|
Beatty, C.V. 2010. Characterization of Small Scale Heterogeneity forPrediction of Acid Fracture Performance. MS thesis, Texas A&MUniversity, College Station, Texas (August 2010).
Blatt, H., Middleton, G., and Murray, R. 1980. Origin of SedimentaryRocks, second edition. Englewood Cliffs, New Jersey: Prentice Hall.
Deng, J. 2010. Mechanical Behavior of Small-Scale Channels in Acid-EtchedFractures. PhD dissertation, Texas A&M University, College Station,Texas.
Deng, J., Hill, A.D., and Zhu, D. 2011. A Theoretical Study of Acid-FractureConductivity Under Closure Stress. SPE Prod & Oper 26(1): 9-17. SPE-124755-PA. http://dx.doi.org/10.2118/124755-PA.
Gangi, A.F. 1978. Variation of whole and fractured porous rock permeabilitywith confining pressure. Int. J. Rock Mech. Min. Sci. & Geomech.Abstracts 15 (5): 249-257. http://dx.doi.org/10.1016/0148-9062(78)90957-9.
Gercek, H. 2007. Poisson's Ratio Values for Rocks. Int. J. Rock Mech.Min. Sci. 44 (1): 1-13.
Gong, M., Lacote, S., and Hill, A.D. 1999. New Model of Acid-FractureConductivity Based on Deformation of Surface Asperities. SPE J. 4 (3): 206-214. SPE-57017-PA. http://dx.doi.org/10.2118/57017-PA.
Hakami, E. and Larsson, E. 1996. Aperture Measurements and Flow Experimentson a Single Natural Fracture. Int. J. Rock Mech. Min. Sci. 33 (4): 395-404.
Mou, J. 2009. Modeling acid transport and non-uniform etching in astochastic domain in acid fracturing. PhD dissertation, Texas A&MUniversity, College Station, Texas (August 2009).
Mou, J., Zhu, D., and Hill, A.D. 2010a. Acid-Etched Channels inHeterogeneous Carbonates—a Newly Discovered Mechanism for CreatingAcid-Fracture Conductivity. SPE J. 15 (2): 404-416.SPE-119619-PA. http://dx.doi.org/10.2118/119619-PA.
Mou, J., Zhu, D., and Hill, A.D. 2010b. A New Acid Fracture ConductivityModel Based on the Spatial Distributions of Formation Properties. Paper SPE127935 presented at the SPE International Symposium and Exhibition on FormationDamage Control, Lafayette, Louisiana, USA, 10-12 February. http://dx.doi.org/10.2118/127935-MS.
Mou, J., Zhu, D., and Hill, A.D. 2011. New Correlations of Acid-FractureConductivity at Low Closure Stress Based on the Spatial Distributions ofFormation Properties. SPE Prod & Oper 26 (2): 195-202.SPE-131591-PA. http://dx.doi.org/10.2118/131591-PA.
Nasr-El-Din, H.A., Al-Driweesh, S.M., Metcalf, A.S., and Chesson, J.B. 2008.Fracture Acidizing: What Role Does Formation Softening Play in ProductionResponse? SPE Prod & Oper 23 (2): 184-191.SPE-103344-PA. http://dx.doi.org/10.2118/103344-PA.
Nierode, D.E. and Kruk, K.F. 1973. An Evaluation of Acid Fluid LossAdditives, Retarded Acids, and Acidized Fracture Conductivity. Paper SPE 4549presented at the Fall Meeting of the Society of Petroleum Engineers of AIME,Las Vegas, Nevada, USA, 30 September-3 October. http://dx.doi.org/10.2118/4549-MS.
Oeth, C., Hill, A.D., Zhu, D., and Sullivan, R. 2011. Characterization ofSmall Scale Heterogeneity to Predict Acid Fracture Performance. Paper SPE140336 presented at the SPE Hydraulic Fracturing Technology Conference, TheWoodlands, Texas, USA, 24-26 January http://dx.doi.org/10.2118/140336-MS.
Pournik, M. 2008. Laboratory-scale fracture conductivity created by acidetching. PhD dissertation, Texas A&M University, College Station, Texas(December 2008).
Ruffet, C.S., Féry, J.J., and Onaisi, A. 1997. Acid-Fracturing Treatment: ASurface-Topography Analysis of Acid-Etched Fractures To Determine ResidualConductivity. SPE J. 3 (2): 155-162. SPE-38175-PA. http://dx.doi.org/10.2118/38175-PA.
Swan, G. 1983. Determination of stiffness and other joint properties fromroughness measurements. Rock Mech. Rock Eng. 16 (1): 19-38.http://dx.doi.org/10.1007/bf01030216.
Walsh, J.B. 1981. Effect of pore pressure and confining pressure on fracturepermeability. Int. J. Rock Mech. Min. Sci. & Geomech. Abstracts 18 (5): 429-435. http://dx.doi.org/10.1016/0148-9062(81)90006-1.
Williams, B.B., Gidley, J.L., and Schechter, R.S. 1979. AcidizingFundamentals, 55. New York: SPE/AIME.