Acid Diversion by Use of Viscoelastic Surfactants: The Effects of Flow Rate and Initial Permeability Contrast
- Abdulwahab H. Al-Ghamdi (Saudi Aramco) | Mohamed A. Mahmoud (King Fahd University of Petroleum and Minerals) | Guanqun Wang (Texas A&M University) | Alfred D. Hill (Texas A&M University) | Hisham A. Nasr-El-Din (Texas A&M University)
- Document ID
- Society of Petroleum Engineers
- SPE Journal
- Publication Date
- December 2014
- Document Type
- Journal Paper
- 1,203 - 1,216
- 2014.Society of Petroleum Engineers
- 4.3.4 Scale, 3.2.4 Acidising, 5.8.7 Carbonate Reservoir, 1.10 Drilling Equipment, 2.5.2 Fracturing Materials (Fluids, Proppant), 1.6.9 Coring, Fishing, 4.1.2 Separation and Treating
- diversion, carbonate, core flood, viscoelastic surfactants, matrix acidizing
- 4 in the last 30 days
- 584 since 2007
- Show more detail
- View rights & permissions
|SPE Member Price:||USD 10.00|
|SPE Non-Member Price:||USD 30.00|
The purpose of matrix stimulation in carbonate reservoirs is to bypass damaged areas and increase the effective wellbore area. This can be achieved by creating highly conductive flow channels known as wormholes. A further injection of the acid will follow a wormhole path where the permeability has increased significantly, leaving substantial intervals untreated. This problem can be more significant as the contrast in permeability increases within the target zones. Diverting materials, such as viscoelastic-surfactants (VES) -based acids, play an important role in mitigating this problem. The acid-injection rate was found to be a critical parameter to maximize the efficiency of the use of VES-based acids as a diverting chemical in addition to creating wormholes. It was found that the maximum apparent viscosity, which developed during VES-based acids injection, occurred over a narrow window of acid-injection rates. Higher injection rates were not effective in enhancing the acidizing process, and the use of diverting material became similar in effect to that of regular acids. The use of VES-based acid was also found to be constrained by the scale of the initial permeability ratio. For initial permeability ratios greater than approximately 10, the diversion was insufficient. The results were obtained by conducting a large set of acidizing experiments by use of 20-in.-long cores. Both single- and parallel-coreflood experiments were performed in this study. Carbonate cores were used with initial permeabilities of 4–150 md, and the flow rate was varied from 1.5 to 50 cm3/min. The initial ratio of permeability between the two cores ranged from 2 to 15. To characterize the wormholes, computerized tomography (CT) was used to generate a 3D view of the wormholes in each core. By use of the results obtained from single cores, the acid-injection rate was found to be a critical parameter in maximizing the efficiency of the use of VES as a diverting agent during matrix-acidizing treatments. Higher injection rates were not effective in enhancing the acidizing process, and the use of diverting material produced results similar to those of regular hydrochloric acid (HCl). Parallel-coreflood experiments indicated that the use was found to be constrained by the scale of the initial permeability ratio. For initial permeability ratios greater than approximately 10, diversion was insufficient in 20-in. coreflood tests. For permeability ratios greater than 10, the acid-placement treatment needs to be designed more carefully.
|File Size||1 MB||Number of Pages||14|
Al-Ghamdi, A.H., Mahmoud, M.A., Hill, A.D., et al. 2009. Diversion and Propagation of Viscoelastic Surfactant Based Acids in Carbonate Cores. Presented at the SPE International Symposium on Oilfield Chemistry, The Woodlands, Texas, 20–22 April. SPE-121713-MS. http://dx.doi.org/10.2118/121713-MS.
Al-Ghamdi, A.H., Mahmoud, M.A., Hill, A.D., et al. 2010. When do Surfactant-Based Acids Work as Diverting Agents? Presented at the SPE International Symposium and Exhibition on Formation Damage Control, Lafayette, Louisiana, 10–12 February. SPE-128074-MS. http://dx.doi.org/10.2118/128074-MS.
Al-Otaibi, M.A., Al-Muntasheri, G.A., Hussein, I.A., et al. 2011. Laboratory Evaluation of Viscoelastic Surfactant Acid Diversion for Carbonate Reservoirs. 2011. Presented at the SPE Middle East Oil and Gas Show and Conference, Manama, Bahrain, 25–28 September. SPE-141993-MS. http://dx.doi.org/10.2118/141993-MS.
Akin, S. and Kovscek, A.R. 2003. Computed Tomography in Petroleum Research. In Application of X-ray Computed Tomography in the Geosciences, ed. F. Mees, R. Swennen, M. Van Geet, P. Jacobs, Vol. 215: 23–28. London, UK: Geological Society of London, London.
Auzerais, F.M., Dussan, E.B., and Reischer, A.J. 1991. Computed Tomography for the Quantitative Characterization of Flow Through a Porous Medium. Presented at the 65th SPE Annual Technical Conference and Exhibition, Dallas, Texas, 6–9 October. SPE-22595-MS. http://dx.doi.org/10.2118/22595-MS.
Buijse, M. and Glasbergen, G. 2005. A Semi-Empirical Model to Calculate Wormhole Growth in Carbonate Acidizing. Presented at the SPE Annual Technical Conference and Exhibition, Dallas, Texas, 19–12 October. SPE-96892-MS. http://dx.doi.org/10.2118/96892-MS.
Chang, F., Qu, Q., and Frenier, W. 2001. A Novel Self-Diverting-Acid Developed for Matrix Stimulation of Carbonate Reservoirs. Presented at the SPE International Symposium on Oilfield Chemistry, Houston, Texas, 13–16 February. SPE-65033-MS. http://dx.doi.org/10.2118/65033-MS.
Daccord, G. and Lenormand, R. 1987. Fractal Patterns from Chemical Dissolution. Nature 325 (6099): 41–43. http://dx.doi.org/10.1038/325041a0.
Fredd, C.N. and Fogler, H.S. 1998. Influence of Transport and Reaction on Wormhole Formation in Porous Media. AIChE J. 44 (9):1933–1949. http://dx.doi.org/10.1002/aic.690440902.
Fredd, C.N. and Fogler, H.S. 1999. Optimum Conditions for Wormhole Formation in Carbonate Porous Media: Influence of Transport and Reaction. SPE J. 4 (3): 196–205. SPE-56995-PA. http://dx.doi.org/10.2118/56995-PA.
Fu, D. and Chang, F. 2005. Composition and Methods for Treating Subterranean Formation. US Patent No. 6,929,070.
Hoefner, M.L. and Fogler, H.S. 1989. Fluid-Velocity and Reaction-Rate Effects During Carbonate Acidizing: Application of Network Model. SPE Prod Eng 4 (1): 56–62. SPE-15573-PA. http://dx.doi.org/10.2118/15573-PA.
Hoefner, M. and Fogler, H.S. 1988. Pore Evolution and Channel Formation During Flow and Reaction in Porous Media. AIChE J. 34 (1): 45–55. http://dx.doi.org/10.1002/aic.690340107.
Jasti, J.K. and Fogler, H.S. 1992. Application of Neutron Radiography to Image Flow Phenomena in Porous Media. AIChE J. 38 (4): 481–488. http://dx.doi.org/10.1002/aic.690380402.
Jasti, J.K. and Fogler, H.S. 1990. Determination of Flow Profiles in Porous Media Using Shifts in Gamma Spectra. AIChE J. 36 (6): 827–836. http://dx.doi.org/10.1002/aic.690360604.
Li, L., Nasr-El-Din, H.A., Crews, J.B., et al. 2011. Impact of Organic Acids/Chelating Agents on the Rheological Properties of an Amidoamine-Oxide Surfactant. SPE Prod & Oper 26 (1): 30–40. SPE-128091-PA. http://dx.doi.org/10.2118/128091-PA.
Lungwitz, B., Fredd, C., Brady, M., et al. 2007. Diversion and Cleanup of Viscoelastic Surfactant-Based Self-Diverting Acid. SPE Prod & Oper 22 (1): 121–127. SPE-86504-PA. http://dx.doi.org/10.2118/86504-PA.
Nasr-El-Din, H.A., Al-Ghamdi, A.H., Al-Qahtani, A.A., et al. 2008. Impact of Acid Additives on the Rheological Properties of a Viscoelastic Surfactant and Their Influence on Field Application. SPE J. 13 (1): 35–47. SPE-89418-PA. http://dx.doi.org/10.2118/89418-PA.
Nasr-El-Din, H.A., Chesson, J.B., Cawiezel, K.E., et al. 2006. Field Success in Carbonate Acid Diversion, Utilizing Laboratory Data Generated by Parallel Flow Testing. Presented at the SPE Annual Technical Conference and Exhibition, San Antonio, Texas, 24–27 September. SPE-102828-MS. http://dx.doi.org/10.2118/102828-MS.
Nasr-El-Din, H.A., Al-Mohammed, A., Al-Aamri, A., et al. 2009. Quantitative Analysis of Reaction Rate Retardation in Surfactant-based Acids. SPE Prod & Oper 24 (1): 107–116. SPE-107451-PA. http://dx.doi.org/10.2118/107451-PA.
Nasr-El-Din, H.A., Al-Nakhli, A., Walton, T., et al. 2009. Application of Cationic Surfactant-Based Fluids for Acid Diversion. SPE Prod & Oper 24 (1): 124–134. SPE-107687-PA. http://dx.doi.org/10.2118/107687-PA.
Tardy, P.M., Lecerf, B., and Christanti, Y. 2007. An Experimentally Validated Wormhole Model for Self-Diverting and Conventional Acids in Carbonate Rocks under Radial Flow Conditions. Presented at the European Formation Damage Conference, Scheveningen, The Netherlands, 30 May–1 June. SPE-107854-MS. http://dx.doi.org/10.2118/107854-MS.
Wang, Y., Hill, A.D., and Schechter, R.S. 1993. The Optimum Injection Rate for Matrix Acidizing of Carbonate Formations. Presented at the SPE Annual Technical Conference and Exhibition, Houston, Texas, 3–6 October. SPE-26578-MS. http://dx.doi.org/10.2118/26578-MS.