Microemulsion Viscosity and its Implications for Chemical EOR : Experimental Results and a Model

Mohsen Tagavifar

Research Showcase in Petroleum and Geosystems Engineering • September 8, 2015

Research  Showcase  Sponsored  by    

Chemical EOR Project Sponsors

Chemical EOR Research Team Faculty and Senior Research Scientists Matthew Balhoff Mojdeh Delshad Chun Huh

Mark McClure Thomas Milner Kishore Mohanty

Quoc Nguyen Gary Pope

Kamy Sepehrnoori Upali Weerasooriya

Administrative Staff Esther Barrientes Joanna Castillo

Scientific Consultant Eric de Rouffignac

Technical Staff Arnob Bhuyan Eric Dao Sophie Dufour Gayani Kennedy

Austin Lim Jith Liyanage Jun Lu Chammi Miller Sujeewa Palayangoda

Krishna Panthi Gayani Pinnawala Tyler Seay Erin Shook Pradeep Wickramasiri

Post Doctoral Fellows and Visiting Scholars JiaJia Cai Nilanka Gurusinghe Sumudu Herath Sung Hyun Jang Erandi Kulawardana

Dharmika Lansakara-P Haishan Luo Mathieu Maubert Suneth Rajapaksha Maryam Shafiekhani

Mohsen Tagavifar Shayan Tavassoli Nadeeka Upamali Peixi Zhu

Chemical EOR Research Team Graduate Students Ali Afsharpoor Almas Aitkulov Reza Beygi Sriram Chandresekhar Leonard Chang Peila Chen Alex Cui Alolika Das Ghazal Dashti Shashvat Doorwar

Mehmet Erincik Pinaki Ghosh Ali Goudarzi Ruth Hahn Taylor Isbell Stephen Jong Paul Jordan Prateek Kathel Aboulghasem Kazemi Heesong Koh

Eun Song Kim Hamid Lashgari Vincent Lee Sean Li Zhitao Li Mohammad Lotfollahi Jun Lu Yiwei Ma Nhut Nguyen Nabi Nizamidin

Jose Parra Pengpeng Qi Eric Schulz Amir Shahmoradi Himanshu Sharma Robin Singh Shayan Tavassoli Songyang Tong Bingqing Wang

Undergraduate Students Alex Bennitt Ryan Casky Alex Chang Lauren Churchwell

Alex Garrido Yong Do Kim Matias Kopinsky Patrick Lim

Willie Martin Joseph Moon Travis Pitcher Christopher Sandwith

Reynaldo Torres Sarah Turley Denning Wang Enakshi Wikramanayake

Objectives •  Improve understanding of surfactant retention and

ways to reduce it

•  Lower the cost of chemical enhanced oil recovery by reducing surfactant retention

Surfactant Retention •  What is surfactant retention?

–  Loss of surfactant during a chemical flood Injected Surfactant – Recovered Surfactant = Surfactant Retention

•  Causes of surfactant retention –  Adsorption on clays and other mineral surfaces –  Phase trapping when injected surfactant solution

forms a mixture with oil that can not be displaced in porous media

•  Microemulsion viscosity •  Salinity gradient

Microemulsions •  Microemulsions are thermodynamically stable mixtures

of oil, water, surfactant and possibly salts, co-solvent •  Three types:

– Type I: oil-in-water – Type III: comparable amount of oil and water in ME – Type II: water-in-oil

•  Type III has ultra-low IFT with both oil and brine phases. This is the underlying principle for chemical EOR to recover residual oil.

•  High microemulsion viscosity causes high surfactant retention

salinity

Effect of Co-solvent on Microemulsion Viscosity •  Reduces the viscosity of Type III microemulsions •  Mitigates the shear thinning behavior

•  Self-assembly of surfactants creates meso-structures:

What Causes High Viscosity?

Differences: (1)  Interface flexibility (2)  Connectivity of oil (brine) domains

lamellar microstructure (interface)

oil brine

disordered bicontinuous (interface)

oil

brine

𝜇↓0 = 𝜇↓∞↑′ +∆𝜇 Newtonian background

Stress from deformation of interfaces

Viscosity:

•  Adding co-solvent: –  Makes the interface more flexible (reduces the bending

modules-𝒌) –  Creates more connections (increases the Gaussian

modulus- 𝒌 ) •  Bicontinuous microemulsion modeled as a two-domain

network:

New Model for Microemulsion Viscosity

(Two parameters: 𝑣, 𝑣↑′ )

𝜇↓0 = (1− 𝜙↓𝑜 )𝜇↓𝑤 exp(𝛼↓1 𝜙↓𝑜 )+ 𝜙↓𝑜 𝜇↓𝑜 exp(𝛼↓2 (1− 𝜙↓𝑜 ))   + 𝜙↓𝑠 𝛼↓3 𝜙↓𝑜 𝜇↓𝑜 exp(𝛼↓4 (1− 𝜙↓𝑜 )+ 𝛼↓5 𝜙↓𝑜 ) 

1/𝜇↓0  = 1− 𝜙↓𝑜 /𝜇↓𝑤 exp(𝜈↑′ 𝜙↓𝑜 )  + 𝜙↓𝑜 /𝜇↓𝑜 exp(𝜈(1− 𝜙↓𝑜 )) 

(Five parameters: 𝛼↓1 , 𝛼↓2 , 𝛼↓3 , 𝛼↓4 , 𝛼↓5 )

Old model in UTCHEM:

𝜈∝𝑘/𝑘↓𝐵 𝑇 , 𝜙↓𝑜 : volume fraction of oil in ME

Comparison of Measurements & Model Example 1

•  30% oil O1; µo=5.5 cP @ 24°C

independent measurements

1/𝜇↓0  = 1− 𝜙↓𝑜 /𝜇↓𝑤 exp(𝜈↑′ 𝜙↓𝑜 )  + 𝜙↓𝑜 /𝜇↓𝑜 exp(𝜈(1− 𝜙↓𝑜 ))   ;    𝜈∝𝑘/𝑘↓𝐵 𝑇 

Comparison of Measurements & Model Example 2 – Non-ideal Behavior

•  30% oil O2; µo=11.9 cP @ 25°C •  0.55% TDA-13PO-SO4, 0.2% C20-24 IOS •  Co-solvent: 1% phenol-2EO

•  30% oil; •  Polymer: HPAM 3630S

Comparison of Measurements & Model Examples 2&3 – Effect of Polymer

Identify and Design Better Chemicals to Lower Microemulsion Viscosity

•  Ethoxylated/Propoxylated co-solvents (IBA-xEO-xPO and Phenol-xEO-xPO)

•  Double-role molecules that act as both co-solvent/surfactant (2-EHS)

Mechanistic Simulations Example of Surfactant Retention by Phase Trapping

•  A surfactant slug (0.3 PV) is injected and then pushed towards producers by a “polymer drive”

•  If polymer drive fails to displace microemulsion, surfactant is retained. •  Movies show surfactant concentration. Pattern is I-5spot and simulator

is UTCHEM.

Salinity gradient: Type I-Type III-Type I Salinity gradient: Type I-Type III-Type III

Surfactant retention=0.094 mg/gr Surfactant retention~0.28 mg/gr

Summary •  Viscosity of optimum microemulsions could be

several times that of oil viscosity. •  Adding co-solvent or branched surfactants is effective

to lower microemulsion viscosity •  New chemicals are developed to lower microemulsion

viscosity –  co-solvents: Ethoxylated/Propoxylated IBA and Phenol – Double-role molecules: 2-EHS

•  A new microemulsion viscosity model is developed, validated, and implemented in UTCHEM to mechanistically simulate chemical EOR processes

Research  Showcase  Sponsored  by    

Thank  you  

Back up slides

Experimental artifacts Example 1: abnormal increase of viscosity with time

•  Dead oil+20% toluene (µo~ 3cP @ 58C) •  0.5% C18-2EO-C18-10PO-2(SO4Na), 0.5%

C12-13-7PO-SO4-, 1% DIPA-5EO; •  Sample is slightly above optimum. •  ARES LS-1 with cone/plate; ~1ml sample volume

“Microemulsions  are  thermodynamically  stable  mixture  …”??  

Experimental artifacts Example 2: incorrect sampling before equilibrium

•  Sample was not equilibrated (microemulsion + macroemulsion at the bottom)

(UV  light)  

Examples 2&3

Shear thinning behavior is also modeled.