Producing-Gas/Oil-Ratio Behavior of Multifractured Horizontal Wells in Tight Oil Reservoirs
- R. Steven Jones Jr. (Newfield Exploration Company)
- Document ID
- Society of Petroleum Engineers
- SPE Reservoir Evaluation & Engineering
- Publication Date
- August 2017
- Document Type
- Journal Paper
- 589 - 601
- 2017.Society of Petroleum Engineers
- hoizontal well, gas-oil ratio, tight oil, unconventional
- 79 in the last 30 days
- 972 since 2007
- Show more detail
- View rights & permissions
|SPE Member Price:||USD 10.00|
|SPE Non-Member Price:||USD 30.00|
Horizontal wells with hydraulic fractures in tight oil reservoirs show producing-gas/oil-ratio (GOR) behavior that is very different from conventional, higher-permeability reservoirs. This paper explains the reasons for the observed behavior by use of reservoir simulation, with field examples from the STACK and SCOOP plays of the Anadarko Basin in central Oklahoma.
A framework for interpreting observed GOR behavior in tight black-oil reservoirs is modeled after the following stages in a well’s history. Some stages may not be visible because of the degree of undersaturation, flowing-bottomhole-pressure schedule, finite-conductivity fractures, and duration of the transient-flow period.
- Stage 1: Early GOR is constant at the initial solution GOR (Rsi) while bottomhole flowing pressure is above the bubblepoint.
- Stage 2: A rise in GOR as bottomhole flowing pressure declines to less than the bubblepoint.
- Stage 3: The transient GOR “plateau”, which is characteristic of transient linear flow.
- Stage 4: A continuous rise in GOR during boundary-dominated flow.
Fundamental differences between linear and radial flow, which cause the dependence of GOR on flowing bottomhole pressure, are explained by use of simulation. During transient linear flow, the GOR response to changes in flowing bottomhole pressure is independent of permeability for infinite-conductivity fractures, but not for finite-conductivity fractures.
Several practical observations are made. Knowing Rsi and the transient-GOR-plateau level in an area can help one interpret where a well is in its GOR history. Rate-transient-analysis (RTA) diagnostic plots are altered by rising GOR, and sometimes show an early unit slope. During boundary-dominated flow, GOR is more a function of cumulative production than of time; wells with closer fracture spacing have a faster GOR rise with time, but also recover oil more quickly. If compound linear flow develops, GOR can decline late in the well life. The Meramec and Woodford formations in STACK can be history matched without invoking a suppressed bubblepoint caused by pore-proximity effects. The critical gas saturation in the Meramec appears to be in the range of 0–5%.
Technical contributions include a framework for interpreting GOR behavior over well life; the effect of changing bottomhole flowing pressure on GOR; the effect of fracture spacing, conductivity, and half-length on GOR; and the effect of GOR on RTA diagnostic plots.
|File Size||2 MB||Number of Pages||13|
Behmanesh, H., Hamdi, H. and Clarkson, C. R. 2015. Analysis of Transient Linear Flow Associated with Hydraulically-Fractured Tight Oil Wells Exhibiting Multi-Phase Flow. Presented at the SPE Middle East Unconventional Resources Conference and Exhibition, Muscat, Oman, 26–28 January. SPE-172928-MS. https://doi.org/10.2118/172928-MS.
Byrnes, A.P. 2003. Aspects of Permeability, Capillary Pressure, and Relative Permeability Properties and Distribution in Low-Permeability Rocks Important to Evaluation, Damage, and Stimulation. Oral presentation given at the Rocky Mountain Association of Geologists Petroleum Systems and Reservoirs of Southwest Wyoming Symposium, Denver, 19 September.
Chaudhary, A. S., Ehlig-Economides, C. A. and Wattenbarger, R. A. 2011. Shale Oil Production Performance from a Stimulated Reservoir Volume. Presented at the SPE Annual Technical Conference and Exhibition, Denver, 30 October–2 November. SPE-147596-MS. https://doi.org/10.2118/147596-MS.
Clarkson, C. R. and Qanbari, F. 2015. An Approximate Analytical Multi-Phase Forecasting Method for MultiFractured Light Tight Oil Wells With Complex Fracture Geometry. Presented at the Unconventional Resources Technology Conference, San Antonio, Texas, 20–22 July. SPE-178665-MS. https://doi.org/10.2118/178665-MS.
Du, L. and Chu, L. 2012. Understanding Anomalous Phase Behavior in Unconventional Oil Reservoirs. Presented at the SPE Canadian Unconventional Resources Conference, Calgary, 30 October–1 November. SPE-161830-MS. https://doi.org/10.2118/161830-MS.
Hagedorn, A. R. and Brown, K. E. 1965. Experimental study of Pressure Gradients Occurring During Continuous Two-Phase Flow in Small-Diameter Vertical Conduits. J Pet Technol 17 (4): 475–484. SPE-940-PA. https://doi.org/10.2118/940-PA.
Honarpour, M. M., Nagarajan, N. R., Orangi, A. et al. 2012. Characterization of Critical Fluid PVT, Rock, and Rock-Fluid Properties–Impact on Reservoir Performance of Liquid Rich Shales. Presented at the SPE Annual Technical Conference and Exhibition, San Antonio, Texas, 8–10 October. SPE-158042-MS. https://doi.org/10.2118/158042-MS.
Hough, E. V. and McClurg, T. 2011. Impact of Geological Variation and Completion Type in the US Bakken Oil Shale Play Using Decline Curve Analysis and Transient Flow Character. AAPG Search and Discovery Article No. 40857, adapted from oral presentation given at the AAPG International Conference and Exhibition, Milan, Italy, 23–26 October.
Jones, R. S. Jr., Pownall, B. and Franke, J. 2014. Estimating Reservoir Pressure From Early Flowback Data. Presented at the Unconventional Resources Technology Conference, Denver, 25–27 August. SPE-2014-1934785-MS. https://doi.org/10.15530/urtec-2014-1934785.
Khoshghadam, M., Khanal, A. and Lee, W. J. 2015. Numerical Study of Impact of Nano-Pores on Gas-Oil Ratio and Production Mechanisms in Liquid-Rich Shale Oil Reservoirs. Presented at the Unconventional Resources Technology Conference, San Antonio, Texas, 20–22 July. SPE-178577-MS. https://doi.org/10.2118/178577-MS.
Mahmoud, I. S. and Anderson, D. M. 2015. Practical Application of Type Curve Analysis to the Interpretation of Multi-Stage Fractured Horizontal Well Data. Presented at the SPE/CSUR Unconventional Resources Conference, Calgary, 20–22 October. SPE-175931-MS. https://doi.org/10.2118/175931-MS.
Mohan, K., Scott, K. D., Monson, G. D. et al. 2013. A Systematic Approach to Understanding Well Performance in Unconventional Reservoirs: A Wolfcamp Case Study. Presented at the Unconventional Resources Technology Conference, Denver, 12–14 August. SPE-168749-MS. https://doi.org/10.1190/URTEC2013-051.
Tran, T., Sinurat, P. D. and Wattenbarger, B. A. 2011. Production Characteristics of the Bakken Shale Oil. Presented at the SPE Annual Technical Conference and Exhibition, Denver, 30 October–2 November. SPE-145684-MS. https://doi.org/10.2118/145684-MS.
Walsh, Mark P. and Lake, Larry W. 2003. Section 12-6, Solution-Gas-Drive Reservoirs. In A Generalized Approach to Primary Hydrocarbon Recovery, First edition. Amsterdam, The Netherlands: Elsevier.
Wang, Y., Yan, B. and Killough, J. 2013. Compositional Modeling of Tight Oil Using Dynamic Nanopore Properties. Presented at the SPE Annual Technical Conference and Exhibition, New Orleans, 30 September–2 October. SPE-166267-MS. https://doi.org/10.2118/166267-MS.
Whitson, C. H. and Sunjerga, S. 2012. PVT in Liquid-Rich Shale Reservoirs. Presented at the SPE Annual Technical Conference and Exhibition, San Antonio, Texas, 8–10 October. SPE-155499-MS. https://doi.org/10.2118/155499-MS.
Whitson, C. H., Lei, G. and Cheng, N. 2014. Liquid-Rich Shale Versus Conventional Depletion Performance. Presented at the SPE/EAGE European Unconventional Resources Conference and Exhibition, Vienna, Austria, 25–27 February. SPE-167788-MS. https://doi.org/10.2118/167788-MS.