Proppant-Conductivity Testing Under Simulated Reservoir Conditions: Impact of Crushing, Embedment, and Diagenesis on Long-Term Production in Shales
- Abhinav Mittal (University of Oklahoma) | Chandra S. Rai (University of Oklahoma) | Carl H. Sondergeld (University of Oklahoma)
- Document ID
- Society of Petroleum Engineers
- SPE Journal
- Publication Date
- August 2018
- Document Type
- Journal Paper
- 1,304 - 1,315
- 2018.Society of Petroleum Engineers
- Proppant conductivity, Diagenesis, Proppant crushing, Embedment, Fines migration
- 11 in the last 30 days
- 395 since 2007
- Show more detail
- View rights & permissions
|SPE Member Price:||USD 12.00|
|SPE Non-Member Price:||USD 35.00|
Hydraulic fractures act as conduits connecting a wellbore to nanodarcy-permeability unconventional reservoirs. Proppants are responsible for enhancing the fracture conductivity, and they help in maintaining high production rates. This study is focused on the measurement of long-term conductivity of proppant packs at simulated reservoir-temperature and pressure conditions. Various conductivity-impairment mechanisms such as proppant crushing, fines migration, embedment, and diagenesis are investigated.
Testing was performed with a conductivity cell that allows simultaneous measurement of fracture compaction and permeability. The proppant-pack performance during compression between metal and shale platens was compared. The proppant-filled fracture (concentration of 0.75-3 lbm/ft2) is subjected to axial load (5,000 psi) to simulate closure stress. Brine (3% NaCl + 0.5% KCl) is flowed through the pack at a constant rate (3 cm3/min) at 250°F during an extended duration of time (10-60 days). In this study, Ottawa sand proppant was used between platen facies fabricated from Vaca Muerta and Eagle Ford shales.
Testing between metal platens indicated that the reduction in permeability with 20/40-mesh Ottawa sand (˜30% during 12 days) was less than that of 60/100-mesh Ottawa sand, which suffered a 99% reduction in only 4 days.
Measurements with 20/40-mesh Ottawa sand between shale platens were conducted at 1.5 lbm/ft2. During a duration of 10 days, the Eagle Ford platens proppant pack exhibits a greater reduction in permeability, in comparison with Vaca Muerta platens. The normalized compaction for Eagle Ford shale platens is 20% more than Vaca Muerta platens because of greater proppant embedment. Particle-size analysis and scanning-electron-microscopy (SEM) images verify proppant crushing, fines migration, and embedment as dominant damage mechanisms. These factors are observed to depend on the testing of shales. The results suggest a substantial degradation of permeability during the initial 5 days of testing, after which the permeability appears to stabilize. Crushed proppant and dislodged shale-surface particles contribute to the fines generated; a greater concentration of fines is observed downstream.
In a separate study between Vaca Muerta platens, under similar closure stress and temperature conditions at 2-lbm/ft2 proppant concentration, the permeability reduced by almost three orders of magnitude during a duration of 60 days. It was also observed that growth of diagenetic smectite is accelerated by making the fluid more basic (pH of 10).
|File Size||1 MB||Number of Pages||12|
Akrad, O. M., Miskimins, J. L., and Prasad, M. 2011. The Effects of Fracturing Fluids on Shale Rock Mechanical Properties and Proppant Embedment. Presented at the SPE Annual Technical Conference and Exhibition, Denver, 30 October–2 November. SPE-146658-MS. https://doi.org/10.2118/146658-MS.
Alramahi, B. and Sundberg, M. I. 2012. Proppant Embedment and Conductivity of Hydraulic Fractures in Shales. Presented at the 46th US Rock Mechanics/Geomechanics Symposium, Chicago, 24–27 June. ARMA-2012-291.
Ballard, B. D. 2007. Quantitative Mineralogy of Reservoir Rocks Using Fourier Transform Infrared Spectroscopy. Presented at the SPE Annual Technical Conference and Exhibition, Anaheim, California, USA, 11–14 November. SPE-113023-STU. https://doi.org/10.2118/113023-STU.
Cooke, C. E. Jr. 1973. Conductivity of Fracture Proppants in Multiple Layers. J Pet Technol 25 (9): 1101–1107. SPE-4117-PA. https://doi.org/10.2118/4117-PA.
Duenckel, R. J., Conway, M. W., Eldred, B. et al. 2011. Proppant Diagenesis—Integrated Analyses Provide New Insights Into Origin, Occurrence, and Implications for Proppant Performance. Presented at the SPE Hydraulic Fracturing Technology Conference, The Woodlands, Texas, USA, 24–26 January. SPE-139875-MS. https://doi.org/10.2118/139875-MS.
Duenckel, R., Moore, N., O’Connell, L. et al. 2016. The Science of Proppant Conductivity Testing—Lessons Learned and Best Practices. Presented at the SPE Hydraulic Fracturing Technology Conference, The Woodlands, Texas, USA, 9–11 February. SPE-179125-MS. https://doi.org/10.2118/179125-MS.
Ghanizadeh, A., Clarkson, C. R., Deglint, H. et al. 2016. Unpropped/Propped Fracture Permeability and Proppant Embedment Evaluation: A Rigorous Core-Analysis/Imaging Methodology. Presented at the Unconventional Resources Technology Conference, San Antonio, Texas, USA, 1–3 August. URTeC-2459818-MS. https://doi.org/10.15530/URTeC-2016-2459818-MS.
Ghosh, S., Rai, C. S., Sondergeld, C. H. et al. 2014. Experimental Investigation of Proppant Diagenesis. Presented at the SPE/CSUR Unconventional Resources Conference-Canada, Calgary, 30 September–2 October. SPE-171604-MS. https://doi.org/10.2118/171604-MS.
Gidley, J. L., Penny, G. S., and McDaniel, R. R. 1995. Effect of Proppant Failure and Fines Migration on Conductivity of Propped Fractures. SPE Prod & Fac 10 (1): 20–25. SPE-24008-PA. https://doi.org/10.2118/24008-PA.
Haynes International. 2016. Hastelloy C-276 Principal Features. http://haynesintl.com/docs/default-source/pdfs/new-alloy-brochures/corrosion-resistantalloys/c-276.pdf?sfvrsn=6.
Kassis, S. M., and Sondergeld, C. H. 2010. Gas Shale Permeability: Effects of Roughness, Proppant, Fracture Offset, and Confining Pressure. Presented at the SPE International Oil & Gas Conference, Beijing, 8–10 June. SPE-131376-MS. https://doi.org/10.2118/131376-MS.
Kumar, V., Sondergeld, C. H., and Rai, C. S. 2012. Nano to Macro Mechanical Characterization of Shale. Presented at the SPE Annual Technical Conference and Exhibition, San Antonio, Texas, USA, 8–10 October. SPE-159804-MS. https://doi.org/10.2118/159804-MS.
LaFollette, R. F., and Carman, P. S. 2010. Proppant Diagenesis: Results So Far. Presented at the SPE Unconventional Gas Conference, Pittsburgh, Pennsylvania, USA, 23–25 February. SPE-131782-MS. https://doi.org/10.2118/131782-MS.
Lejay, A., Larmier, S., Rutman, P. et al. 2017. The Role of Porosity in the Development of Parallel Bedded Calcite Filled Fractures (or Beef) in the Vaca Muerta: An Integrated Analysis From High Resolution Core Data. Presented at the SPE/AAPG/SEG Unconventional Resources Technology Conference, Austin, Texas, USA, 24–26 July. URTeC-2668071-MS. https://doi.org/10.15530/URTEC-2017-2668071.
Mittal, A., Rai, C. S., and Sondergeld, C. H. 2017. A Study of Propped-Fracture Conductivity: Impairment Mechanisms Under Laboratory Conditions. Presented at the SPWLA 58th Annual Symposium, Oklahoma City, Oklahoma, USA, 17–21 June. SPWLA-2017-CC.
Palisch, T., Duenckel, R., Chapman, M. A. et al. 2010. How to Use and Misuse Proppant Crush Tests: Exposing the Top 10 Myths. SPE Prod & Oper 25 (3): 345–354. SPE-119242-PA. https://doi.org/10.2118/119242-PA.
Palisch, T. 2016. Introduction to Hydraulic Fracturing and Proppant. University of Oklahoma–PE Tech Talk.
Penny, G. S. 1987. An Evaluation of the Effects of Environmental Conditions and Fracturing Fluids Upon the Long-Term Conductivity of Proppants. Presented at the 62nd Annual Technical Conference and Exhibition, Dallas, 27–30 September. SPE-16900-MS. https://doi.org/10.2118/16900-MS.
Pioneer Investor Presentation. 2017. http://investors.pxd.com/phonix.zhtml?c=90959&p=irolpresentations. pp. 12–17.
Shukla, P., Kumar, V., Curtis, M. et al. 2013. Nanoindentation Studies on Shales. Presented at the 47th US Rock Mechanics/Geomechanics Symposium, San Francisco, 23–26 June. ARMA-2013-578.
Sondergeld, C. H. and Rai, C. S. 1993. A New Concept in Quantitative Core Characterization. The Leading Edge 12 (7): 774–779. https://doi.org/10.1190/1.1436968.
Weaver, J. D., Parker, M., van Batenburg, D. W. et al. 2007. Fracture-Related Diagenesis May Impact Conductivity. SPE J. 12 (3): 272–281. SPE-98236-PA. https://doi.org/10.2118/98236-PA.
Zhang, J., Ouyang, L., Hill, A. D. et al. 2014. Experimental and Numerical Studies of Reduced Fracture Conductivity Due to Proppant Embedment in Shale Reservoirs. Presented at the SPE Annual Technical Conference and Exhibition, Amsterdam, 27–29 October. SPE-170775-MS. https://doi.org/10.2118/170775-MS.