Hydraulic Fracturing Stimulation in Unconventional Reservoirs: The Recent Advanced Technology in

Hydraulic Fracturing Fluids

Presented By:

Abdulaziz Ellafi, Ph.D. Candidate at UND

▪ Research Assistant/Reservoir Engineer, Energy & Environmental Research Center (EERC), 2020

▪ Graduate Research and Teaching Assistant, Petroleum Eng. Department at UND, 2018

▪ Master’s Degree from Missouri University of Science and Technology, MO, USA, 2018

▪ Bachelor’s Degree from University of Tripoli, Libya, 2011

Contact Information:

Email: abdulaziz.ellafi@und.edu

LinkedIn: https://www.linkedin.com/in/abdulaziz-ellafi-767275138/

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Presentation Outline

▪ Overview of Unconventional Reservoirs

▪ Bakken Petroleum System (BPS), Williston Basin

▪ Problem Statement

▪ Challenges Related to High Water Production in the Bakken

▪ Water Management Options

▪ Experimental and Simulation Studies

▪ Conclusions

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Overview of Unconventional Reservoirs

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Daily crude oil production in Eagle Ford and Bakken Petroleum System (U.S. Energy Information

Administration , 2020)

Bakken Formation, Williston Basin

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Modern Horizontal Drilling and Multi-Stage Hydraulic Fracturing

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Problem Statement

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Features of Produced Water

Produced waters salinity range in the United States (Otton and Mercier, 2015).

FW PW1

Specific Gravity 1.00 1.20

pH 8.07 4.83

Chloride (ppm) 50-630 163,637

Sulfate (ppm) 11 40

Aluminum (ppm) 0 1.42

Boron (ppm) 0 20.30

Barium (ppm) 0 5.69

Calcium (ppm) 304 29,222

Iron (ppm) 0 34.60

Potassium (ppm) 0 1,660

Magnesium (ppm) 30 4,347

Sodium (ppm) 4 70,342

Strontium (ppm) 0 2,204

TDS (ppm) 237-988 267,588

Hardness (ppm) 328 >20

Table 1: Chemical composition of the produced water analysis from Permian Basin.

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Challenges Related to High Water Production in the Bakken

The change in water cut over time in the U.S shale plays (Male, 2019).

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Water Management Options

Schematic of the process (Miller, 2003).

Schematic of MSF process (Miller, 2003).

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Water Disposal Methods

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0

Flowback water Treatment

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Fontenelle et al., 2013 introduced smart water treatment using electrochemical process for flowback and produced

waters, which does not remove dissolved ions. This technology separate colloidal organic and inorganic materials.

FW PW1 PW2 PW3

PW3 after treated

water

Specific Gravity 1.00 1.20 1.10 1.20 1.10

pH 8.07 4.83 6.21 5.3 7.5

Chloride (ppm) 50-630 163,637 118,000 166,014 166,152

Sulfate (ppm) 11 40 N/D 12 17

Aluminum (ppm) 0 1.42 N/D 1 1

Boron (ppm) 0 20.30 N/D 23.3 28

Barium (ppm) 0 5.69 N/D 8 8

Calcium (ppm) 304 29,222 9,480 29,755 29,875

Iron (ppm) 0 34.60 5.1 13 4

Potassium (ppm) 0 1,660 N/D 1,692 1,705

Magnesium (ppm) 30 4,347 N/D 4,629 4,452

Sodium (ppm) 4 70,342 N/D 74,562 76,427

Strontium (ppm) 0 2,204 N/D 1,777 1,791

TDS (ppm) 237-988 267,588 125,300 275,053 277,095

Hardness (ppm) 328 >20 12,740 36 18

Economic Analysis

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Cost Analysis ($/bbl) Freshwater Wastewater

Supply $ 0.25 - $ 3 $ 0.0 - $ 0.5

Transport $ 0.65 - $ 5.0 $ 2.0 - $ 9.0

Storage - $ 2.0 - $ 4.0

Disposal - $ 0.5 - $ 1.75

Bakken Well Performance

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Bakken Formation Characterization and Produced Water

Mineral analysis results of the Middle Bakken Formation samples.

Constituents Produced Water

Aluminum(ppm) 0.42

Barium(ppm) 33

Bromide(ppm) 816

Calcium(ppm) 22,400

Bicarbonates(ppm) 61

Chloride(ppm) 189800

Conductivity (µS/cm) 257

Dissolved Oxygen 8.24

Fluorine(ppm) 33

Iron(ppm) 34.60

Lithium(ppm) 60

Magnesium(ppm) 1430

Nitrate(ppm) 64

pH 2.94

Potassium(ppm) 7400

Sodium(ppm) 89500

Specific gravity 1.20

Strontium(ppm) 1540

Sulfate(ppm) 197

TDS (mg/L) 268,588

TPH (ppm) >20

TSS (mg/L) 10,623

Turbidity (NTU) 182

Table 2. Chemical composition of the Bakken Formation produced water.

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Fracture Treatment Fluids in Past and Present

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Type of FRs Chemical Name Chemical Structure

Non-ionic PAM Polyacrylamide

Anionic PAM

Polyacrylamide-co-acrylic acid,

hydrolyzed polyacrylamide

Poly-acrylamido-2-

methylpropane sulfonate

Cationic PAM Poly (acrylamide-co-N,N,N-

trimethyl-2-((1-oxo-2-propenyl)oxy))

Table 2. Types and chemical structures of friction reduces (FRs) (Xiong et al., 2018).

Anionic HVFRs in High TDS Environment

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Viscosity Profile

Ba Geri et al., 2019

Ba Geri et al., 2019

Cationic HVFRs have been successfully used in up to 100% produced water. However, this fluid can not be

compatible with formation rocks, such Bakken formation due to negatively charged that might cause formation

damage. On the other hand, anionic HVFRs tend to have minimum formation damage, but can’t tolerate high TDS

level of salt water.

The viscosity and elasticity (n’ & k’) are crucial factors to develop better fracturing fluids

Enhancing Anionic HVFRs in High TDS Environment

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The work of Seymour et al., 2018 showed that the addition of suitable surfactants can improve

performance and extend the salt tolerance of HVFRs. Also, study of Gu et al., 2019 concluded a

surfactant–polymer mixture has the advantages of strong shear resistance, drag reduction polymer to

mechanical and thermal degradation and the micelle structure’s critical concentration is reduced.

Seymour et al., 2018

Pressure reduction using friction loop

Gu et al., 2019

Bead model of the surfactant–polymer mixture

HVFR Viscosity Profiles Measurement

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Dilution

(%)TDS (ppm)

Hardness

(ppm)pH Iron (ppm)

Sulfate

(ppm)

Chloride

(ppm)

Bakken

Produced

Water

173,00022,400,00

0 2.9 152000 816000 189800

Grand

Forks Tap

Water

277 - 7.9 - - -

90%

FW/10%

PW

31,300 2,240,000 6.7 15200 81600 18980

70%

FW/30%

PW

84,300 6,720,000 6.2 45600 244800 56940

50%

FW/50%

PW

91,200 1,120,000 6.1 76000 408000 94900

Table 3. Summary of HVFRs fluids characterization case scenarios

HVFR Viscosity Profiles Measurement

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HVFRs samples at different levels of produced water.

Base Case Case#1 Case#2 Case#3

Dilution Ratios 100%FW 90%FW/10%PW 70%FW/30%PW 50%FW/50%PW

Dosage 0.25 to 8.0gpt 0.25 to 8.0gpt 6gpt & 8gpt 8gpt

Experiment

Temperature70⁰F and 150⁰F 70⁰F and 150⁰F 70⁰F and 150⁰F 70⁰F and 150⁰F

Table 4. Summary of HVFRs fluids characterization case scenarios.

HVFR Viscosity Profiles Measurement

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Viscosity Profile of HVFR Fracturing Fluid blend at 100% Bakken Tap Water at 70⁰F (right) and 50%

Bakken Produced Water at 70 ⁰F and 150 ⁰F.

Implementation Simulation Test

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Reservoir Simulation Model

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Reservoir Simulation Model

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Case Study: Middle Bakken Formation

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Treatment Cases(#)

Type of Fluids(Name)

Pump Rate(bpm)

Final Proppant Concentration

(Ibm/gal)

Proppant Size(mesh)

Case Study #1 Slickwater 50 2 40/70

Case Study #2 Linear Gel 50 2 40/70

Case Study #3 HVFR-PR 50 2 40/70

Case Study #4 HVFR-PRS 50 2 40/70

Table 5. Summary of re-stimulation case scenarios.

Pre-Re-fracturing Simulation Well Flow Behaviors

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Results and Analysis

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Case Study #1

Results and Analysis

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Case Study #2

Results and Analysis

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Case Study #3

Results and Analysis

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Effect of Fracturing Fluid Types on Bakken Oil Well Production

Conclusions

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In this study, a comprehensive study was employed for the application of produced water with fracturing fluids in

unconventional shale plays, such as the Bakken Formation. The research findings point out the following:

▪ The freshwater availability has decreased with increasing associated costs, which leads to impacts on human

health, agriculture, livestock, and wildlife. The water treatment process can help to reduce contaminate

groundwater resources and toxic air emissions due to transportation and disposal operations.

▪ The research outcomes could contribute to practices in other countries that have unconventional resources,

such as Saudi Arabia, Russia, China, Argentina, and Libya, especially some of these nations already face

challenges of availability of clean water.

▪ The separation process of the organic and inorganic materials from the flowback water may be the best option

to treat produced water with low cost and effective application that would be successfully used with fracturing

fluids, such as crosslinked and friction reducers fluids.

Conclusions Cont.

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▪ The common type of HVFRs is anionic fluid due to its lower cost and better drag reduction. Although anionic

HVFRs tend to have minimum formation damage but cannot tolerate a high TDS level of saltwater and more

sensitive to Iron constituent.

▪ Cationic HVFRs have been successfully used in up to 100% produced water with the lower-cost operation, but

cationic HVFRs may not be compatible with formations that contain a high amount of quartz and/or clay

(Bakken Formation).

▪ This paper enhanced the ability of anionic HVFRs in Bakken produced water condition by using dilute water (for

example 10% to 50% instead of using the water treatment and freshwater). The research outcomes concluded

that increasing in HVFRs dosage (8 gpt) can extend the performance of frac-fluids when 50% of produced water

is used.

Conclusions Cont.

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▪ The simulation results showed the surfactant as additives modified the rheological properties of HVFRs in harsh

conditions by preventing degradation, reducing viscosity, expanding fluid viscoelasticity, and extending the flow

behavior index (n’) and flow consistency index (k’) performance of the fracturing fluids to be able to carry

proppant deeper into secondary and tertiary fractures. Surfactant might be a good candidate to enhance the

unfolding time anionic HVFRs in high TDS conditions and cold water as well as improving oil recovery from

unconventional shale plays.

Publications

▪ Ellafi, A., Ba Geri, M., Bubach, B., & Jabbari, H. (2019a, August 28). Formation Evaluation and Hydraulic Fracture Modeling of

Unconventional Reservoirs: Sab'atayn Basin Case Study. American Rock Mechanics Association.

▪ Ellafi, A., Jabbari, H., Ba Geri, M., & Alkamil, E. (2019b, November 11). Can HVFRs Increase the Oil Recovery in Hydraulic

Fractures Applications? Society of Petroleum Engineers. doi:10.2118/197744-MS

▪ Ellafi, A., Jabbari, H., Wan, X., Rasouli, V., Ba Geri, M., & Al-Bazzaz, W. (2020a). How Does HVFRs in High TDS Environment

Enhance Reservoir Stimulation Volume? International Petroleum Technology Conference (IPTC) 2020 IPTC-20138

▪ Ellafi, A., Jabbari, H., Tomomewo, O., Mann, M., and Ba Geri, M. (2020b) ‘Future of Hydraulic Fracturing Application in Terms of

Water Management and Environmental Issues: A Critical Review ', Society of Petroleum Engineers (SPE), (SPE-199993-MS)

▪ Ba Geri, Noles, J., Kim, S., & Ellafi, A. (2020). New Developed Mathematical Model for Predicting Viscosity Profile and Proppant

Transport Utilizing HVFRs Dosage with Produced Water. Society of Petroleum Engineers. doi:10.2118/ 201433-MS

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Acknowledgment

▪ The authors would like to acknowledge the North Dakota Industrial Commission (NDIC), Petroleum

Research Fund for their financial support of this work, through the contract NDIC G-045-89. The financial

support of the North Dakota Industrial Commission (NDIC) is highly appreciated.

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Thank You for your attention!

Questions?

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