Connectivity Analysis; Understanding Waterflood Behavior, Connectivity for EOR Analysis Richard Baker September-2012 Jackson Hole Wyoming
Outline Executive Summary Background/What are we trying to do? Target Identification (communication analysis) Controlling hot streak flow Conclusions
Executive Summary I Examination of 12 waterflooded fields and over 2000 injector-producer pairs (1400 well pairs in sandstones) We studied the nature of heterogeneity between wells using communication analysis (connectivity analysis) Flow in these waterflooded fields is controlled by two components; Waterflood Induced Fractures Matrix controlled flow 3 2012 Baker Hughes Incorporated. All Rights Reserved.
Results of communication analysis work (connectivity); Stress orientation western Canada controlling flow is typically NE-SW Examining the early water breakthrough plots and injectivity analysis indicates the presence of fracture flow at early times At late times, good reservoir management and shear failure often mitigates the effect of on trend fractures Waterflood Induced Fracture (Geomechanics) is important factor controlling flow 4 2012 Baker Hughes Incorporated. All Rights Reserved.
BACKGROUND/WHAT ARE WE TRYING TO DO? 5 2012 Baker Hughes Incorporated. All Rights Reserved.
EOR selection Typically select on fluid type, lithology Waterflood Gas flood CO2 Chemical flooding Understand how fluids flow in reservoir 6 2012 Baker Hughes Incorporated. All Rights Reserved.
What are we trying to do? The need to differentiate these two cases is critical Fracture or small volume hot streak K hot streak >> K matrix (50 times) Matrix dominated flow + Large volume in hot streak K hot streak > K matrix (2-10 times) 7 2012 Baker Hughes Incorporated. All Rights Reserved.
Why??? Fracture or small volume hot streak K hot streak >> K matrix (50 times) Matrix dominated flow + Large volume in hot streak K hot streak > K matrix (2-10 times) 8 2012 Baker Hughes Incorporated. All Rights Reserved.
Figure 1: North American Stress Orientation Map 18 (stars ae field locations annotated by authors) http://www.worldatlas.com/webimage/ countrys/na.htm 9 2012 Baker Hughes Incorporated. All Rights Reserved.
WHAT ARE WE DOING? Study of 1400 well pairs in sandstone in Western Canada (waterflooded) 2000 pairs in total Connectivity or communication analysis 10 2012 Baker Hughes Incorporated. All Rights Reserved.
11 2012 Baker Hughes Incorporated. All Rights Reserved. General experience in North America is that induced Waterflood Fractures control flow more than we think
Objectives of Work. A key question though is; what type of heterogeneity controls flow? Is it matrix flow, induced hydraulic fracture flow or both? SPE 161177 Analysis of Flow and the Presence of Fractures and Hot Streaks in Waterflood Field Cases Richard Baker, Tim Stephenson, Crystal Lok, Predrag Radovic, Robert Jobling, Cameron McBurney, How can we control injected fluid if we have a combination of induced hydraulic fractures + matrix flow?
WHAT ARE WE DOING? CONNECTIVITY/ COMMUNICATION ANALYSIS 13 2012 Baker Hughes Incorporated. All Rights Reserved.
What are we doing? 1 2 3 Figure 18: Types of Communication Strengths Map view
What are we doing? Light blue water injection rates Dark blue water production rates Green Oil rates 15
How do we use production data to determine pathways? long term data Short term data Example of Watercut map used as surveillance data from Beliveau SPE Time (days)
Objective of Communication Analysis Map of communicating well pairs We want to identify key wells that communicate
What was done? We examine 1400 well pairs in sandstone reservoirs under waterflood in WCSB using communication analysis method Five waterfloods in non fractured high permeability Sandstone reservoirs Successful waterfloods None of the waterfloods are considered to be naturally fractured Figure 1: North American Stress Orientation Map 18 (stars are field locations annotated by authors)
Early Waterflood Behavior The stress orientation controlling flow is typically NE-SW in western Canada. Examining the early water breakthrough plots and the hall plots indicates the presence of fracture flow.
Early Waterflood Behavior Water breakthrough usually occurred in a on trend direction (NE-SW) On trend NE-SW Water cut Off trend NE-SW NW-SE Time
INJECTOR ANALYSIS 21 2012 Baker Hughes Incorporated. All Rights Reserved.
Monthly Injection Pressures vs. Injection Rates over Two Year Period; VRR~1 Reservoir Theoretical Pressure line constant Based on Darcy s flow constant res. pressure Wellhead Injection Pressure Injection Rate
Injection Pressures vs. Injection Rates over Two Year Period; VRR~1 Reservoir Pressure constant Fracture pressure ~ 4 300 KPA (0.75-0.43) psi/ft x600 m KB Banding behavior @ same ~pressures (3000-4000 Kpa) Theoretical line Based on Darcy s flow Injection Rate
Hall Plot; Evidence of Induced Fractures Injection pressure Injection rate Hall integral Injection rate drops by ½ but injection pressure is constant
Entire Field Late Stage Analysis 1 mile Early stage waterflood (NE/SW)
Zoom in Portion of Field What has happened? Partial conversion to line drive but also Communication is now East- West 1 mile
Rose Diagram of Entire Fields Connectivity The rose plots generated by the communication analysis tool indicate no preferential flow direction in late stage waterfloods, this indicates; 1) matrix flow and/or 2) shear failure fractures.
What is happening???? Early Stages; Map View Off trend well On trend well NE-SW Good initial response Water cut rise first
What is happening???? Early Stages; Map View Off trend well Water movement initially NE-SW On trend well NE-SW Watered out Or injector
What is happening???? Late Stage Waterflood; Map View Off trend well On trend well NE-SW Watered out Or injector Growth in fractures On trend well NE-SW Watered out Or injector
Mental Model Check Injection pressure constant (2-3 times injection rates) Initial communication in stress direction; NE-SW (on trend) Late stage communication in off trend direction Either simple matrix flow Or Shear fractures (constant wellhead injection pressure) Probably both
Recap Targeting Study In 10-50% of the wells we see strong communication between individual injectors and producer probably via fractures Flow in these waterflooded fields is controlled by two components; Fracture and/or high permeability matrix flow (hot streaks) Matrix controlled flow
So what can we do with this knowledge? Decrease injection pressures Change producer into injectors (streamline patterns) Gel treatment/polymer
SASKATCHEWAN Sandstone thickness=3-4 M μ oil ~350cP μ polymer =7cP API ~13 HISTORY MATCHED ~90 WELLS ON WATERFLOOD SIMULATION STUDY
Field BC Perm=15 D Perm=1 md
Oil Production non rate control Waterflood Polymer 20% Slug Polymer Gel Method Incremental RF Ultimate RF Waterflood 27% Polymer Flood 5 32% Gel Treatment 3 30% Gel Treatment w/ Polymer Flood 11 38%
40 Series 1 35 30 25 20 15 Series 1 10 5 0 waterflood alone polymer flood alone gel alone polymer flood +gel
Comparison of Communication Analysis with Waterflood Case (Blind test)
Conclusions Flow in these waterflooded fields is controlled by two components; Waterflood Hydraulic Induced Fractures (not NFR) Matrix Examining the early water breakthrough plots and injection pressures and rates indicates the presence of fracture flow at early times P inj P frac extension At late times, good reservoir management and shear failure fracture often mitigates the effect of on trend fractures c
Background references Richard Baker, Tim Stephenson, Crystal Lok, Predrag Radovic, Robert Jobling, Cameron McBurney; Analysis of Flow and the Presence of Fractures and Hot Streaks in Waterflood Field Cases Heffer, K., Zhang, X., Koutsabeloulis, N., Main, I., Li, L., Identification of Activated (Therefore Potentially Conductive) Faults and Fractures Through Statistical Correlations in Production and Injection Rates and Coupled Flow Geomechanical Modelling, presented at SPE Europe Annual Conference and Exhibition held in London, United Kingdom, 11-14 June 2007. Heffer, K., Greenhough, J., Main, I.G., Zhang, X., Hussein, A.M., Koutsabeloulis, N., Low-cost Monitoring of Inter-well Reservoir Communication Paths Through Correlations in Well Rate Fluctuations: Case Studies From Mature Fields in the North Sea, presented at SPE Europec/EAGE Annual Conference and Exhibition held in Barcelona, Spain, 14-17 June 2010 40 2012 Baker Hughes Incorporated. All Rights Reserved.