Effect of Shear Rate on the Propagation of Polymer-Based In-Situ-Gelled Acids Inside Carbonate Cores
- Ahmed M. Gomaa (Texas A&M University) | Mohamed A. Mahmoud (Texas A&M University) | Hisham A. Nasr-El-Din (Texas A&M University)
- Document ID
- Society of Petroleum Engineers
- SPE Production & Operations
- Publication Date
- February 2011
- Document Type
- Journal Paper
- 41 - 54
- 2011. Society of Petroleum Engineers
- 1.6.9 Coring, Fishing, 5.5.2 Core Analysis
- 0 in the last 30 days
- 751 since 2007
- Show more detail
- View rights & permissions
|SPE Member Price:||USD 12.00|
|SPE Non-Member Price:||USD 35.00|
In-situ-gelled acids that are based on polymers have been used in the field for several years and were the subject of many laboratory studies. An extensive literature survey reveals that there are conflicting opinions about using these acids. These acids were used in the field with mixed results. Recent laboratory work indicated that these acids can cause damage under certain conditions. There is no agreement on when this system can be applied successfully in the field.
A coreflood study was conducted using Indiana limestone cores (1.5-in. diameter and 20-in. length) at high temperatures and pressures. Propagation of the acid, polymer, and crosslinker inside the long cores was examined in detail. Samples of the core effluent were collected, and the concentrations of calcium, crosslinker, and acid were measured. Permeability enhancement and location of any precipitation was detected using a computed-tomagraphy (CT) scanner on the core before and after the acid injection. Different sections were cut from the core to investigate the propagation and precipitation of polymer and crosslinker. Material balance was conducted to determine the amount of crosslinker retained in the core.
Experimental results show that this acid system caused damage in some cases. At low shear rates, in-situ-gelled acid formed a gel inside the core as indicated by the cyclic behavior noted in the pressure drop across the core, and the acid changed direction inside the core several times. However, this gel reduced the core permeability significantly. At high shear rates, a smaller amount of gel was formed inside the core, and the acid's ability to change its direction inside the core was less than that noted at low shear rate. A significant permeability enhancement was achieved. The wormhole length increased as the shear rate was increased, while the diameter of the wormhole increased as the cumulative injected volume of acid increased. CT scan indicated the presence of gel residue inside and around the wormhole. Gel residue increased at low shear rates. Material balance performed on the crosslinker indicated that a significant amount of the crosslinker was retained in the core. This amount increased at low shear rates.
|File Size||1 MB||Number of Pages||14|
Abdel Fatah, W., Nasr-El-Din, H.A., Moawad, T., and Elgibaly, A. 2008. Effects of Crosslinker Type andAdditives on the Performance of In-Situ Gelled Acids. Paper SPE 112448presented at the SPE International Symposium and Exhibition on Formation DamageControl, Lafayette, Louisiana, USA, 13-15 February. doi: 10.2118/112448-MS.
Amro, M.M. 2006. ExtendedMatrix Acidizing Using Polymer-Acid Solutions. Paper SPE 106360 presentedat the SPE Technical Symposium of Saudi Arabia Section, Dhahran, Saudi Arabia,21-23 May. doi: 10.2118/106360-MS.
Chang, F., Qu, Q., and Frenier, W. 2001. A Novel Self-Diverting Acid Developedfor Matrix Stimulation of Carbonate Reservoirs. Paper SPE 65033 presentedat the SPE International Symposium on Oilfield Chemistry, Houston, 13-16February. doi: 10.2118/65033-MS.
Chang, F.F., Qiu, X., and Nasr-El-Din, H.A. 2007. Chemical Diversion Techniques Usedfor Carbonate Matrix Acidizing: An Overview and Case Histories. Paper SPE106444 presented at the International Symposium on Oilfield Chemistry, Houston,28 February-2 March. doi: 10.2118/106444-MS.
Conway, M.W., Asadi, M., Penny, G., and Chang, F. 1999. A Comparative Study ofStraight/Gelled/Emulsified Hydrochloric Acid Diffusivity Coefficient UsingDiaphragm Cell and Rotating Disk. Paper SPE 56532 presented at the SPEAnnual Technical Conference and Exhibition, Houston, 3-6 October. doi:10.2118/56532-MS.
Dick, M.A., Heinz, T.J., Svoboda, C.F., and Aston, M. 2000. Optimizing the Selection of BridgingParticles for Reservoir Drilling Fluids. Paper SPE 58793 presented at theSPE International Symposium on Formation Damage, Lafayette, Louisiana, USA,23-24 February. doi: 10.2118/58793-MS.
Gomaa, A.M. and Nasr-El-Din, H.A. 2010. New Insights Into the Viscosity ofPolymer-Based In-Situ Gelled Acids. SPE Prod & Oper 25 (3): 367-375. SPE-121728-PA. doi: 10.2118/121728-PA.
Halder, S., Nainwal, S.P., De, S.K., and Karmaker, G.P. 2004. In-situ Cross-linking Acid DivertingAgent (ISCADA): A New Solution to Stimulate Multi-layered Reservoirs. PaperSPE 88591 presented at the SPE Asia Pacific Oil and Gas Conference andExhibition, Perth, Australia, 18-20 October. doi: 10.2118/88591-MS.
Hill, A.D. and Rossen, W.R. 1994. Fluid Placement and Diversion inMatrix Acidizing. Paper SPE 27982 presented at the University of TulsaCentennial Petroleum Engineering Symposium, Tulsa, 29-31 August. doi:10.2118/27982-MS.
Hill, D.G. 2005. Gelled Acid. US Patent Application No. 20050065041.
Izgec, O., Key, R., Zhu, D., and Hill, A.D. 2008. An Integrated Theoretical andExperimental Study on the Effects of Multiscale Heterogeneties in MatrixAcidizing of Carbonates. Paper SPE 115143 presented at the SPE AnnualTechnical Conference and Exhibition, Denver, 21-24 September. doi:10.2118/115143-MS.
Kalfayan, L.I. and Martin, A.N. 2009. The Art and Practice of AcidPlacement and Diversion: History, Present State and Future. SPE 124141presented at the SPE Annual Technical Conference and Exhibition, New Orleans,4-7 October. doi: 10.2118/124141-MS.
Lynn, J.D. and Nasr-El-Din, H.A. 2001. A Core Based Comparison of theReaction Characteristics of Emulsified and In-Situ Gelled Acids in LowPermeability, High Temperature, Gas Bearing Carbonates. Paper SPE 65386presented at the SPE International Symposium on Oilfield Chemistry, Houston,13-16 February. doi: 10.2118/65386-MS.
MaGee, J., Buijse, M.A., and Pongratz, R. 1997. Method for Effective Fluid DiversionWhen Performing a Matrix Acid Stimulation in Carbonate Formations. PaperSPE 37736 presented at the Middle East Oil Show, Bahrain, 17-20 March. doi:10.2118/37736-MS.
Mirza, A. and Turton, S. 1995. Selective Stimulation of VaryingCharacteristic Carbonate Reservoir Using Acid Activated Gel Diverter. PaperSPE 29824 presented at the Middle East Oil Show, Bahrain, 11-14 March. doi:10.2118/29824-MS.
Mohamed, S.K., Nasr-El-Din, H.A., and Al-Furaidan, Y.A. 1999. Acid Stimulation of Power WaterInjectors and Saltwater Disposal Wells in a Carbonate Reservoir in SaudiArabia: Laboratory Testing and Field Results. Paper SPE 56533 presented atthe SPE Annual Technical Conference and Exhibition, Houston, 3-6 October. doi:10.2118/56533-MS.
Nasr-El-Din, H.A., Taylor, K.C., and Al-Hajji, H.H. 2002. Propagation of Cross-Linkers Used inIn-Situ Gelled Acids in Carbonate Reservoirs. Paper SPE 75257 presented atthe SPE/DOE Improved Oil Recovery Symposium, Tulsa, 13-17 April. doi:10.2118/75257-MS.
Rojas, M.R., Müller, A.J., and Sáez, A.E. 2008. Shear rheology and porousmedia flow of wormlike micelle solutions formed by mixtures of surfactants ofopposite charge. Journal of Colloid and Interface Science 326 (1): 221-226. doi:10.1016/j.jcis.2008.07.022.
Saxon, A., Chariag, B., and Abdel Rahman, M.R. 2000. An Effective Matrix DiversionTechnique for Carbonate Reservoirs. SPE Drill & Compl 15 (1): 57-62. SPE-62173-PA. doi: 10.2118/62173-PA.
Taylor, K.C. and Nasr-El-Din, H.A. 2002. Coreflood Evaluation of In-SituGelled Acids. Paper SPE 73707 presented at the International Symposium andExhibition on Formation Damage Control, Lafayette, Louisiana, USA, 20-21February. doi: 10.2118/73707-MS.
Taylor, K.C. and Nasr-El-Din, H.A. 2003. Laboratory Evaluation of In-SituGelled Acids for Carbonate Reservoirs. SPE J. 8 (4):426-434. SPE-87331-PA. doi: 10.2118/87331-PA.
Taylor, K.C., Nasr-El-Din, H.A., and Al-Alawi, M.J. 1999. Systematic Study of Iron ControlChemicals Used During Well Stimulation. SPE J. 4 (1):19-24. SPE-54602-PA. doi: 10.2118/54602-PA.
Woo, G.T., Lopez, H., Metcalf, A.S., and Boles, J. 1999. A New Gelling System for AcidFracturing. Paper SPE 52169 presented at the SPE Mid-Continent OperationsSymposium, Oklahoma City, Oklahoma, USA, 28-31 March. doi:10.2118/52169-MS.
Yeager, V. and Shuchart, C. 1997. In-Situ Gels Improve Formation Acidizing.Oil & Gas Journal 95 (3): 70-72.