Enhancing Oil Recovery

MD Simulations of Low-Salinity Enhanced Oil Recovery

Tom Underwood, Valentina Erastova, H. Chris Greenwell

thomasunderwood.github.io

CMS 2016

This Presentation

A brief introduction to...

• Low-salinity enhanced oil recovery.
• The role of clay minerals.
• Some cool results.
• Some conclusions and questions.

Global Energy Demand

By the year 2035 it is predicted that worldwide energy consumption will have increased by approximately 35%.


Current oil extraction methods only recover approximately a third of the oil within a reservoir.





Optimising oil extraction rates is a big problem!

A Possible Solution...

Enhanced oil recovery (EOR) is a technique used to improve the oil output from a reservoir.

Using a flooding fluid with lower salinity (compared to seawater) has been shown to improve oil extraction rates, hence low-salinity EOR.

Research Questions

Low-salinity EOR works, but the fundamental mechanisms are not well understood.

Can we use simulations to aid our understanding of low-salinity EOR?

Can our results help increase oil extraction yield?

Technical Details

The Main Story...

There are several conditions required for low-salinity EOR:

• A low-salinity flood!

• Divalent cations in formation water.

• Polar components in the oil.

• The presence of clay minerals.

Our aim is to analyse these conditions using MD.

Part 1: Let us examine...

• A low-salinity flood!

• Divalent cations in formation water.

• Polar components in the oil.

• The presence of clay minerals.

Montmorillonite and Decane

Pyrophyllite and Decane

Kaolinite and Decane

What do the simulations tell us about
the presence of clay minerals?

• Different clays have significantly different properties.
• Clays with large CEC are not a major player in low-sal EOR.
• This agrees with recent experimental results whereby
  kaolinite plays a dominant role.

  R. Kareem et al. (201x) FILL

Part 2: let us examine...

• A low-salinity flood!
• Divalent cations in formation water.
• Polar components in the oil.
• The presence of clay minerals.

Montmorillonite and Decanoic Acid

What about the pH?

...but wait...

• A low-salinity flood!
• Divalent cations in formation water.
• Polar components in the oil.
• The presence of clay minerals.

What about divalent cations?

What's going on?

What do the simulations tell us about
polar components in the oil?

• We must consider pH to fully understand EOR.
• Cation bridging occurs with divalent ions.
• Ionic content is very important!

Part 3: let us examine...

• A low-salinity flood!
• Divalent cations in formation water.
• Polar components in the oil.
• The presence of clay minerals.

What about salt concentration?

What do the simulations tell us about
about the salt concentration?

There is no correlation between salt concentration and oil-clay interactions at the molecular level.

Is this result suprising?

What else could cause the low-salinity effect?

Take home message...

Ionic content > Ionic concentration

Overall Conclusions

MD simulations offer an ideal opportunity to interpret the phenomenon of low-salinity EOR at the molecular level.

We have been able to successfully describe some of the experimental observations of low-salinity EOR.

The low-salinity aspect remains elusive however.

I would like to thank...

Prof. Chris Greenwell

Dr. Valentina Erastova

Dr. Pablo Cubillas

Rikan Kareem