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Complementary Workflows for Analyzing Multiphase Flowback and Post-flowback Production Data In Unconventional Reservoirs Open Access


Other title
Effective pore volume, half length, load recovery, ultimate load recovery
Short term period flowback rate and pressure
Flowback drive index indices mechanism
Long term hydrocarbon oil gas forecast
Fate of fracturing fluid left in ineffective fracture
Gas desorption effect in matrix
Complementary flowback and post-flowback analysis
Dynamic relative permeability
Analysis Equation, Diffusivity Equation, Darcy Equation
Shut in, spontaneous and forced imbibition, leak off
Pseudo steady state, unit slope
Primary fracture, hydraulic fracture
Laplace transform, Gaver Stefhest algorithm, inversion
Pay recovery
Flowback sequence
Monte carlo, probability density function, cumulative distribution function
Horn River, Anadarko, Muskwa, Evie, Cardium, Bakken
Non linear fit, regression, generalized reduced gradient, evolutionary algorithm
Linear, bilinear, half, quarter, slope
Unconventional tight oil, gas, sand, Shale reservoir Formation
Bulk, macroscopic, permeability and porosity
Initial gas, oil, water volume and saturation in fracture
Material balance time
Pressure supercharge
Flowback guided production data analysis
Cross plot, flow regime, flow region
Model verification with IMEX CMG
Fracture closure, compaction drive, expansion drive, gas drive, oil drive, hydrocarbon drive
Pore volume differentiation
Multi stage horizontal well, pad
Reactivated natural fracture, micro fracture, secondary fracture
Type curve history matching
Reduction of uncertainty in fracture and reservoir estimate
Spacing aspect ratio, fracture intensity
Water skin, block
Quadrilinear flow model, dual porosity, simultaneous triple porosity model
Transient multiphase depletion, rapid saturation change
Type of item
Degree grantor
University of Alberta
Author or creator
Ezulike, Obinna D
Supervisor and department
Dehghanpour, Hassan (Civil and Environmental Engineering)
Examining committee member and department
Chalaturnyk, Rick (Civil and Environmental Engineering)
Leung, Juliana (Civil and Environmental Engineering)
Nouri, Alireza (Civil and Environmental Engineering)
Dehghanpour, Hassan (Civil and Environmental Engineering)
Haghighi, Manouchehr (Petroleum Engineering)
Department of Civil and Environmental Engineering
Petroleum Engineering
Date accepted
Graduation date
2017-11:Fall 2017
Doctor of Philosophy
Degree level
The application of horizontal drilling and hydraulic fracturing techniques has resulted in the economic production of previously inaccessible hydrocarbon trapped in very-low permeability reservoirs such as Shale gas/oil, tight gas and tight oil. Although the economic production of these reservoirs supplement the decreasing hydrocarbon supply from conventional reservoirs to meet the world’s growing energy demand, modeling fluid flow in such complex reservoirs to minimize environmental pollution remains challenging. There have been improvements in the quality and frequency of rate and pressure measurements during fluid production from multi-stage fractured wells and in the ability of existing transient models to interpret multiphase flowback and post-flowback production data. However, the existing models either make many simplistic assumptions or are too complex. The simplistic nature of some of these models could result in overestimation or underestimation of reservoir parameters and hydrocarbon forecasts. The complexity of some of these models introduces high uncertainty in the estimates of resulting parameters such as fracture pore-volume, half-length and permeability. This study presents complementary workflows for the qualitative and quantitative analysis of flowback and post-flowback production data. The data are obtained from multifractured horizontal wells completed in low permeability reservoirs with a significant amount of reactivated natural fractures. The workflows are based on three key models proposed in the study, namely – flowback tank model, flowback analysis model and quadrilinear flow model. The main results from this work are summarized in the following paragraphs. The occurrence of pseudo-steady state flow regime during intermediate flowback periods suggests a "pressure supercharge" effect in the fracture network. Rate and pressure data from this flow regime can be analyzed to estimate key fracture properties (e.g. effective pore-volume and initial average gas saturation in the active fracture network) and drive mechanisms (i.e. fracture closure, gas expansion and water depletion). Fracture closure effects play a significant role in the physics of fluid flow during early flowback periods. However, fluid expansion becomes the dominant drive mechanism towards the end of flowback in gas wells. Flowback data from tight oil wells are dominated by single phase, water depletion during early time periods (about 100 hours). This is unlike many Shale gas wells, which show immediate gas and water production. The concept of dynamic-relative-permeability was proposed to capture the transient, multiphase, fluid saturations in the effective fracture network during flowback. The resulting model enables complementary, 2-phase flowback and post-flowback production data analysis. Qualitative production data analysis show that there is a general correlation between: load recovery and flowback sequence; effective fracture pore volume and flowback sequence; and cumulative water production and effective fracture pore volume. The restriction of comparative load recovery analysis to wells completed in the same formation produces better correlations. Also, this qualitative analysis provides a way to estimate the percentage of the total injected volume left inside and outside the active fracture network respectively. Quantitative production data analysis provides estimates of the pore-volume of active fracture networks, effective half-length and initial gas volume in hydraulic fractures during flowback. This analysis shows that the gas desorption effects from the matrix and the communication interface between secondary fractures and hydraulic fractures, significantly increases as production progresses from flowback to post-flowback periods.
This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for the purpose of private, scholarly or scientific research. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.
Citation for previous publication
Ezulike, D. O., Dehghanpour, H., Virués, C., Hawkes, V. R. and Jones, Steven R. 2016. Flowback Fracture Closure: A Key Factor for Estimating Effective Pore-Volume. SPE Reservoir Engineering & Evaluation.
, D. O. and Dehghanpour, H. 2016. Characterizing Tight Oil Reservoirs with Dual- and Triple-Porosity Models. Journal of Energy Resources Technology,
, D. O. and Dehghanpour, H. 2016. Capturing the Effects of Secondary Fractures on Production Data Using Flow Regime Equations and Specialised Plots: An Uncertainty Analysis Approach. Journal of Petroleum Science and Engineering,
j.petrol.2015.11.016.Ezulike, D. O., Adefidipe, O. A., Fu, Y., Dehghanpour, H., Virués, C., Bearinger, D., Hawkes, V. R. and Jones, Steven R. 2015. Flowback Fracture Closure: A Key Factor for Estimating Effective Pore-Volume. Paper SPE- 175143-MS presented at the SPE Annual Technical Conference and Exhibition, Houston, Texas, USA.
, D. O. and Dehghanpour, H. 2015. A Complementary Approach for Uncertainty Reduction in Post-flowback Production Data Analysis. Journal of Natural Gas Science and Engineering,
, D. O., Ghanbari, E., Siddiqui, S. and Dehghanpour, H. 2015. Pseudo-steady State Analysis in Linear Tight Oil Reservoirs. Journal of Petroleum Science and Engineering,
, D. O. and Dehghanpour, H. 2014. Development of Specialized Plots for Production Data Analysis of Tight Reservoirs with Secondary Fractures. Paper SPE 171589 presented at SPE CURC held in Calgary, Alberta, Canada, 30 September – 2 October.
, D. O., Dehghanpour, H., Virués, C. and Hawkes, V. R. 2014. A Flowback-Guided Approach for Production Data Analysis in Tight Reservoirs. Paper SPE 171636 presented at SPE CURC held in Calgary, Alberta, Canada, 30 September – 2 October.
, D. O., Dehghanpour, H. 2014. A Worflow for Flowback Data Analysis – Creating Value out of Chaos. Paper UrTEC 1922047 presented at Unconventional Technology Conference held in Denver, Colorado, USA, 25 – 27 August.Ezulike, D. O. and Dehghanpour, H. 2014. Modeling Flowback as a Transient Two-Phase Depletion Process. Journal of Natural Gas Science and Engineering,
, D. O. and Dehghanpour, H. 2014. A Model for Simultaneous Matrix Depletion into Natural and Hydraulic Fracture Networks. Journal of Natural Gas Science and Engineering,
, D. O., Dehghanpour, H. and Hawkes, V. R. 2013. Understanding Flowback as a Transient 2-Phase Displacement Process: An Extension of the Linear Dual-Porosity Model. Paper SPE 167164 presented at SPE CURC held in Calgary, Alberta, Canada, 5 – 7 November.
, D. O., Dehghanpour, H. 2013. Characterizing Tight Oil Reservoirs Using Dual- and Triple-Porosity Models. Paper SPE 167126 presented at SPE CURC held in Calgary, Alberta, Canada, 5 – 7 November.

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