A New Cationic Polymer System That Improves Acid Diversion in Heterogeneous Carbonate Reservoirs
- Abhishek Sarmah (Texas A&M University) | Ahmed Farid Ibrahim (Texas A&M University) | Hisham Nasr-El-Din (Texas A&M University) | Jennifer Jackson (BASF Corporation)
- Document ID
- Society of Petroleum Engineers
- SPE Journal
- Publication Date
- April 2020
- Document Type
- Journal Paper
- 2020.Society of Petroleum Engineers
- diversion, in-situ gelled acid, acidizing
- 19 in the last 30 days
- 54 since 2007
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In-situ gelled acids are used for acid diversion in heterogeneous carbonate reservoirs. However, most of the gelled systems are based on anionic polymers that are difficult to clean up after the acid treatments. Residual polymer deposition leads to formation damage by blocking pore throats in the matrix. This work evaluates a new cationic-polymer acid system with self-breaking ability for application as an acid diverter in carbonate reservoirs.
Experimental studies have been conducted to examine the rheological properties of these polymer-based acid systems. The apparent viscosities of the live and the partially neutralized acids at pH from 0 to 5 were measured against the shear rate (0 to 1000 s–1). The effects of salinity and temperature (80 to 250°F) on the rheological properties of the acid system were also studied. The viscoelastic properties of the gelled acid system were evaluated using an oscillatory rheometer. Dynamic sweep tests were used to determine the elastic (G') and viscous (G'') moduli of the system. Single-coreflood experiments were conducted on Indiana limestone cores to study the nature of diversion caused by the polymer-acid system. The effect of permeability contrast on the process of diversion was investigated by conducting dual-coreflood experiments on Indiana limestone cores that had permeability contrasts of 1.5 to 20. Computed tomography (CT) scans were conducted to study wormhole propagation after acid injection for both single and dual cores.
The live acid system displayed a non-Newtonian shear-thinning behavior with the viscosity declining as temperature increased. For 5 wt% hydrochloric acid (HCl) and 20 gal/t polymer content at 10 s–1, the viscosity decreased from 230 to 40 cp as the temperature increased from 88 to 250°F. Acid-spending tests demonstrated that the acid generated a gel with improved viscosity of 260 cp (at 250°F and 10 s–1) after it reached a pH of 2. The highly viscous gel plugged the wormhole and forced the acid that followed to the next higher-permeability zone. The viscosity of the gel continued to increase until it broke down to 69 cp (at 250°F and 10 s–1) at a pH of 4.8, which indicates a self-breaking system and more thorough cleanup potential. Coreflood studies indicated that the wormhole and the diversion process are dependent on the temperature and the flow rate. There was no indication of any damage caused by the system. The injected acid pore volume to breakthrough (PVBT) decreased from 2.2 to 1.4 when the temperature increased from 150 to 250°F.
The strong elastic nature of the gel (G' = 3.976 Pa at 1 Hz) formed by the partially neutralized acid system proves its suitability as a candidate for use as a diverting agent. This new acid-polymer system has significant promise for use in acid diversion to improve stimulation of carbonate reservoirs.
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Abdelfatah, E., Bang, S., Pournik, M. et al. 2017. Acid Diversion in Carbonates with Nanoparticles-Based In Situ Gelled Acid. Paper presented at the Abu Dhabi International Petroleum Exhibition & Conference, Abu Dhabi, UAE, 13–16 November. SPE-188188-MS. https://doi.org/10.2118/188188-MS.
Ahmed, W. A. F., Nasr-El-Din, H. A., Moawad, T. M. et al. 2008. Effects of Crosslinker Type and Additives on the Performance on In-Situ Gelled Acids. Paper presented at the SPE International Symposium and Exhibition on Formation Damage Control, Lafayette, Louisiana, USA, 13–15 February. SPE-112448-MS. https://doi.org/10.2118/112448-MS.
Amro, M. M. 2006. Extended Matrix Acidizing Using Polymer-Acid Solutions. Paper presented at the SPE Technical Symposium of Saudi Arabia Section, Dhahran, Saudi Arabia, 21–23 May. SPE-106360-MS. https://doi.org/10.2118/106360-MS.
ASTM G31-12a, Standard Guide for Laboratory Immersion Corrosion Testing of Metals, eighth edition. 2012. West Conshohocken, Pennsylvania, USA: ASTM International.
Chang, F., Qu, Q., and Frenier, W. 2001. A Novel Self-Diverting-Acid Developed for Matrix Stimulation of Carbonate Reservoirs. Paper presented at the International Symposium on Oilfield Chemistry, Houston, Texas, USA, 13–16 February. SPE-65033-MS. https://doi.org/10.2118/65033-MS.
Conway, M. W., Asadi, M., Penny, G. S. et al. 1999. A Comparative Study of Straight/Gelled/Emulsified Hydrochloric Acid Diffusivity Coefficient Using Diaphragm Cell and Rotating Disk. Paper presented at the SPE Annual Technical Conference and Exhibition, Houston, Texas, USA, 3–6 October. SPE-56532-MS. https://doi.org/10.2118/56532-MS.
Economides, M. J., Hill, A. D., and Ehlig-Economides, C. 1993. Petroleum Production Systems. Englewood Cliffs, New Jersey, USA: Prentice Hall.
Gomaa, A. M., Mahmoud, M. A., and Nasr-El-Din, H. A. 2011a. Laboratory Study of Diversion Using Polymer-Based In-Situ-Gelled Acids. SPE Prod & Oper 26 (3): 278–290. SPE-132535-PA. https://doi.org/10.2118/132535-PA.
Gomaa, A. M., Mahmoud, M. A., and Nasr-El-Din, H. A. 2011b. Effect of Shear Rate on the Propagation of Polymer-Based In-Situ-Gelled Acids Inside Carbonate Cores. SPE Prod & Oper 26 (1): 41–54. SPE-142927-PA. https://doi.org/10.2118/142927-PA.
Gomaa, A. M. and Nasr-El-Din, H. A. 2010. New Insights into the Viscosity of Polymer-Based In-Situ-Gelled Acids. SPE Prod & Oper 25 (3): 367–375. SPE-121728-PA. https://doi.org/10.2118/121728-PA.
Haldar, S., Nainwal, S. P., De, S. K. et al. 2004. In-Situ Cross-Linking Acid Diverting Agent (ISCADA): A New Solution To Stimulate Multi-Layered Reservoirs. Paper presented at the SPE Asia Pacific Oil and Gas Conference and Exhibition, Perth, Australia, 18–20 October. SPE-88591-MS. https://doi.org/10.2118/88591-MS.
Hill, D. G. 2005. Gelled Acid. US Patent No. 20050065041A1.
Hosseinzadeh, B., Bazargan, M., Rostami, B. et al. 2017. Modeling of Wormhole Propagation in Carbonate Rocks by Use of In-Situ-Gelled Acids. SPE J. 22 (6): 2032–2048. SPE-186101-PA. https://doi.org/10.2118/186101-PA.
Jones, A. T. and Davies, D. R. 1998. Quantifying Acid Placement: The Key to Understanding Damage Removal in Horizontal Wells. SPE Prod & Fac 13 (3): 163–169. SPE-50975-PA. https://doi.org/10.2118/50975-PA.
Lynn, J. D. and Nasr-El-Din, H. A. 2001. A Core Based Comparison of the Reaction Characteristics of Emulsified and In-Situ Gelled Acids in Low Permeability, High Temperature, Gas Bearing Carbonates. Paper presented at the SPE International Symposium on Oilfield Chemistry, Houston, Texas, USA, 13–16 February. SPE-65386-MS. https://doi.org/10.2118/65386-MS.
MaGee, J., Buijse, M. A., and Pongratz, R. 1997. Method for Effective Fluid Diversion when Performing a Matrix Acid Stimulation in Carbonate Formations. Paper presented at the Middle East Oil Show and Conference, Manama, Bahrain, 15–18 March. SPE-37736-MS. https://doi.org/10.2118/37736-MS.
Maheshwari, P., Maxey, J., and Balakotaiah, V. 2016. Reactive-Dissolution Modeling and Experimental Comparison of Wormhole Formation in Carbonates with Gelled and Emulsified Acids. SPE Prod & Oper 31 (2): 103–119. SPE-171731-PA. https://doi.org/10.2118/171731-PA.
Mahmoud, M. 2017. Determination of the Optimum Wormholing Conditions in Carbonate Acidizing Using NMR. J Pet Sci Eng 159: 952–969. https://doi.org/10.1016/j.petrol.2017.10.004.
Miniawi, M. A., Ahmed, W. A. F., Ali, Y. et al. 2007. In Situ Gelled Acid as a Diverting System in Water Injection Well. Paper presented at the SPE/IADC Middle East Drilling and Technology Conference, Cairo, Egypt, 22–24 October. SPE-108264-MS. https://doi.org/10.2118/108264-MS.
Mohamed, S. K., Nasr-El-Din, H. A., and Al-Furaidan, Y. A. 1999. Acid Stimulation of Power Water Injectors and Saltwater Disposal Wells in a Carbonate Reservoir in Saudi Arabia: Laboratory Testing and Field Results. Paper presented at the SPE Annual Technical Conference and Exhibition, Houston, Texas, USA, 3–6 October. SPE-56533-MS. https://doi.org/10.2118/56533-MS.
Patil, P. R., Sarda, A., George, S. et al. 2012. Non-Iron-Based Composition for In-Situ Crosslinked Gelled Acid System. Paper presented at the SPE International Production and Operations Conference and Exhibition, Doha, Qatar, 14–16 May. SPE-156190-MS. https://doi.org/10.2118/156190-MS.
Rabie, A. I., Gomaa, A. M., and Nasr-El-Din, H. A. 2011. Reaction of In-Situ-Gelled Acids with Calcite: Reaction-Rate Study. SPE J. 16 (4): 981–992. SPE-133501-PA. https://doi.org/10.2118/133501-PA.
Ratnakar, R. R., Kalia, N., and Balakotaiah, V. 2013. Modeling, Analysis and Simulation of Wormhole Formation in Carbonate Rocks with In Situ Cross-Linked Acids. Chem Eng Sci 90: 179–199. https://doi.org/10.1016/j.ces.2012.12.019.
Saxon, A., Chariag, B., and Rahman, M. R. A. 2000. An Effective Matrix Diversion Technique for Carbonate Formations. SPE Drill & Compl 15 (1): 57–62. SPE-62173-PA. https://doi.org/10.2118/62173-PA.
Schechter, R. S. 1992. Oil Well Stimulation, first edition. Englewood Cliffs, New Jersey, USA: Prentice-Hall.
Taylor, K. C. and Nasr-El-Din, H. A. 2003. Laboratory Evaluation of In-Situ Gelled Acids for Carbonate Reservoirs. SPE J. 8 (4): 426–434. SPE-87331-PA. https://doi.org/10.2118/87331-PA.
Woo, G. T., Lopez, H., Metcalf, A. S. et al. 1999. A New Gelling System for Acid Fracturing. Paper presented at the SPE Mid-Continent Operations Symposium, Oklahoma City, Oklahoma, USA, 28–31 March. SPE-52169-MS. https://doi.org/10.2118/52169-MS.
Yeager, V. and Shuchart, C. 1997. In-Situ Gels Improve Formation Acidizing. Oil Gas J 95 (3): 70–72.