Culgi’s molecular models for Shell EOR

Shell scientists build nano-scale models of chemically enhanced oil recovery.

Fluid flow reservoir studies may involve giga cell models, but they won’t be fine-grained enough for in-depth understanding of chemical enhanced oil recovery (EOR). A new publication*, includes a chapter on the application of computer simulations to surfactant chemical EOR by researchers from Shell Global Solutions and Culgi.

Surfactant EOR is used to recover residual oil left in the reservoir after flooding. Finding the right surfactant formula is a complex and time consuming process that needs to be tailored to the oil composition. Previously, many surfactant-solvent combinations had to be tested in the laboratory.

Now Culgi proposes computer modeling as a more elegant and rapid approach to surfactant formulation. Starting from the molecular structure of the surfactant and the oil, Culgi and Shell have developed a novel ‘method of moments’ approach to calculate microemulsion properties such optimum salinity, from dissipative particle dynamics (DPD) simulations of mixtures of surfactant, solvent and complex oils. Culgi’s software uses a multi-scaled approach to combine molecular structure with thermodynamics.

DPD simulations model surfactants at the molecular level. A typical simulation is performed in a rectangular box with sides of a few nanometer length containing around 100 surfactant molecules and 1,000 oil molecules. These run on desktop computers. More rigorous models with millions of particles are said to be within the reach of current computational power.

* Analytical Methods in Petroleum Upstream Applications, Jan-Willem Handgraaf et al. CRC Press 2015.

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