Modelling hydraulic fracturing and new insights for increased recovery
Ian D. Gates ([email protected]), Nancy Chen, Ron Wong, Jacky Wang, Xuemin Huang, Mahta Sadeghvishkaei, Belladonna Maulianda
Dept. of Chemical and Petroleum Engineering
Schulich School of Engineering University of Calgary
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IntroducMon
§ Modelling Hydraulic Fracturing is Difficult – the Physics involves MulMphase Fluid Flow, ParMcle Transport, Geomechanical DeformaMon, Rock Fracturing, ParMcle Embedment, Temperature Changes, …
§ AnalyMc Models such as PKN and KGD are simplisMc and have severe assumpMons
§ At this point, very few reservoir simulaMon based models have predicMve capability that can be calibrated and run rapidly
§ Highlight today some of our modelling and experimental acMviMes
Four Thrusts of Current Research
1. Simple Reservoir SimulaMon Models for Hydraulic Fracturing using the Quad Model – these models approximate matrix + natural fracture system as conMnuum § Rich in MulMphase Flow Physics, Lean in Geomechanics
2. Geomechanical Finite Element Analysis Models with Fluid Invasion § Rich in Geomechanics, Lean in Fluid Flow (Single Phase Only)
3. GeostaMsMcal Geomechanical Models § The beginnings of integrated MulMphase Flow and Complex
Geomechanics
4. MulMphase Flow in Fractures and Gaps § Experiments – insights for mulMphase flow
Most often used in steam fracturing in Cyclic Steam Stimulation (Beattie-Boberg McNab 1991) Porosity depends on Pore Pressure; Permeability depends on Porosity –
thus Permeability depends on Pore Pressure
Simple Dilation-Recompaction Model:
Dynamic Fracturing – Quad Model
• 1400 m long horizontal well at depth equal to 2835 m • Hydraulic fracturing - 18 stages • Water based fracturing fluid plus nitrogen plus proppants • Initial reservoir pressure: 37,000 kPa • Fracturing pressure: 48,000 kPa • Injection bottom hole pressure: 60,000 kPa Reservoir Properties - heterogeneous model: • Average Permeability: 1.7 mD; Std. Dev. 0.17 mD • Average Porosity: 0.08; Std. Dev. 0.008 • Compressibility: 10-6 1/kPa
• Two Stages • For Injection, do Time Stretch (Scale Hydraulic Fracturing
Operation to Occur Over Simulated Days rather than Minutes) • No Time Stretch done for Production
Case Study
• Pure Prediction Mode – all data taken from logs, core, literature data • Porosity Evolution
Case Study
• Pure Prediction Mode – all data taken from logs, core, literature data • Permeability Evolution
Case Study
• Oil Production
Case Study
• Pure Prediction Mode – all data taken from logs, core, literature data • Oil Saturation Evolution – at end pressure drive depleted
Case Study
• Use fluid invasion into rock to understand stress and pressure evolution in reservoir rock
• Use Abaqus – a finite element analysis package that supports fluid injection into porous media
• Simple model for now – linear elastic rock + Forchheimer modification of Darcy`s law for Fluid
• Size of Stimulated Reservoir Volume (SRV) constrained by Microseismic Data
• Glauconite Formation, Hoadley Field, Alberta • From analysis can estimate nature of fractured rock in SRV
Finite Element Analysis
Injection Port
• Evolution of Pore Pressure
Results
Prior to Run
Initial Condition
After 1 s
After 552 s
After 1102 s
After 2250 s • To match bottom hole pressure, SRV effective permeability = 22.3 D
Maximum Horizontal Stress
Results Minimum Horizontal Stress
Minimum Horizontal Stress
From pressure and flow rate, can back out an interpretation of the fractures created during hydraulic fracturing To match 22.3 D, one realization: 1.46 mm, major fractures = 4 with spacing 14.8 m, minor fractures = 12 with spacing 14.5 m
• Construct detailed heterogeneous 3D earth models of reservoir rock including flow and geomechanical properties and state of stress
• Surface to Understrata Model • Investigating state of stress in the Montney Formation at Initial State
(Pre-Hydraulic Fracturing)
• Model from 500 m to 3500 m, 15 km x 15 km area
Geostatistical Geomechanical Models
Wells positions used in this study (from Accumap, 2014) Wells highlighted by the radial spokes had GR and RHOB log data Wells with the box also had sonic log data.
Sonic logs Sonic logs
Sonic logs
Sonic logs
Source Data – Montney Formation
Data
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Well No. UWI DTC/DTS
LOGS GR LOG RHOB LOG
1 09-22-063-03W6
2 09-30-063-04W6
3 05-31-063-04W6
4 16-34-063-05W6
5 04-35-063-05W6
6 01-06-064-03W6
7 12-07-064-03W6
8 09-05-064-04W6
9 04-09-064-04W6
10 09-12-064-04W6
11 12-14-064-04W6
12 11-18-064-04W6
13 09-23-064-04W6
14 08-29-064-04W6
15 11-09-064-05W6
16 02-28-064-05W6
17 12-20-063-04W6
18 06-24-063-05W6
Summary of available well data for constructing the mechanical earth model (dark color indicates data exists)
Comparison of UCS estimated from Sonic Logs to Core Mechanical Data
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Blue line is UCS from sonic log Points are core data
From 500 m Down
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Lithology BEARPAW BELLYRV WAPIABI COLRAD MUSKIKI CARD CARDSD KASKAPAU 2WSPK DPECK SHAFTBR BFSC PEACERV FALHBSD FALHCSD FALHDSD FALHESD WILRICH BLUSKY GETH CADOMIN FERNIE MONTNEY CHARLK DOIG BELLOY DEBOLTL
3D Earth model
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Porosity (%)
Density (g/cm3)
3D Earth model – Poisson’s ratio
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09-‐30-‐063-‐03W6
Long Name Short Name TVD (m) MD (m)
BELLY RIVER BELLYRV 942.0 942.0 PUSKWASKAU PUSKWSK 1278.8 1278.8 COLORADO COLRAD 1378.6 1378.6 BADHEART BADHRT 1482.6 1482.6 MUSKIKI MUSKIKI 1497.6 1497.6 CARDIUM CARD 1540.0 1540.0
CARDIUM SAND CARDSD 1559.0 1559.0 KASKAPAU KASKAPAU 1604.2 1604.2 DUNVEGAN DUNVG 1964.9 1964.9 SHAFTESBURY SHAFTBR 2063.4 2063.4
BASE OF FISH SCALES BFSC 2126.3 2126.3 PADDY PADDY 2199.5 2199.5
CADOTTE CADOTT 2212.2 2212.2 HARMON HARMON 2238.4 2238.4 NOTIKEWIN NOTIK 2248.4 2248.4
FALHER A SAND FALHASD 2276.1 2276.1 FALHER B SAND FALHBSD 2315.2 2315.2 FALHER C SAND FALHCSD 2334.8 2334.8 FALHER D SAND FALHDSD 2386.8 2386.8 FALHER E SAND FALHESD 2454.7 2454.7
WILRICH WILRICH 2476.7 2476.7 BLUESKY BLUSKY 2532.5 2532.5 GETHING GETH 2556.1 2556.1 CADOMIN CADOMIN 2651.7 2651.7 NIKANASSIN NIKANSN 2670.2 2670.2
FERNIE FERNIE 2716.2 2716.2 NORDEGG NORD 2792.6 2792.6
CHARLIE LAKE CHARLK 2816.3 2816.3 MONTNEY MONTNEY 2864.3 2864.3
3D Earth model – Young’s modulus (GPa)
• Oil-water co- and counter current flow in thin gaps (both smooth and rough) – atmospheric pressure system
• With and without surfactants • If funding arrives, will expand to look at fate of particles in flow
Flow in Fractures
Can configure in horizontal or vertical arrangement with co- and countercurrent flow
• Examining phase interference and interface development
Results
• Examining phase interference and interface development
Results
Final Remarks • Quad Model can model dynamic fracturing process to create fracture network and
fractured zone • Quad Model does not create fractures but reflects impact of fractured zone (or
fracture rock network) on formation properties • Oil flow dynamics suggest that gas injection (cyclic) may have benefit as drive/
displacement process as seen in CSS
• Finite element analysis provides tools to understand potential configurations of fracture networks in reservoir rock and interaction of hydraulic and natural fractures
• Mechanical stratigraphy provides a framework to compare formations and it can be described by standard log-based measurements such as the rock density, sonic velocity, and GR
• Variability of mechanical properties implies that they may be optimum well placement for HF – work is ongoing on this at this point
• Experiments reveal hysteresis of relative permeability – need to be used in HF simulations – HF = re-saturation/saturation as invasion / oil in flow occurs
• Work in progress – stay tuned
Acknowledgements
• Seven Generations • NSERC • Accumap • Schlumberger • Computer Modelling Group