Multiscale Computational Chemistry: How Molecular Modelling Accelerates Innovation in the Oil & Gas Industry

Abstract

Abstract Chemical Enhanced Oil Recovery (CEOR) is a method developed to recover the remaining oil from the fields by injecting a mixture of chemicals into the well to create type III microemulsion. Formulation design of such mixture to a specific crude is challenging and time-consuming. Recent developments in computational chemistry methodologies applied to the Oil and Gas industry showed great potential in being used to develop such mixtures. Work from the 1990s and recent advancements in coarse-grained computational chemistry has shown that a stable type III microemulsion presents 3 main properties: an ultra-low interfacial tension (∼10−3 mN/m), a torque value close to 0, and a high bending rigidity (∼ kBT). We developed a methodology combining the automatic generation of molecules from patent literature, their coarse-graining and parameterization, and the simulation of a synthetic crude/surfactant/brine system where the interfacial properties are measured. We investigate the potentiality of exclusively using simulation to understand the influence of molecule composition and how modifying their structure can lead to a potential candidate for synthesis. We selected 3 main surfactant structures from 3 different patents: a linear multicarboxylate, a linear sulfonate, and a Gemini-type surfactant. We automatically generated 24 structures consisting exclusively of a combination of polyethylene oxide, ethylene oxide, or carbon groups. Results from the numerical simulation showed that linear surfactants may not be optimum to form type III microemulsion without the addition of a co-surfactant due to poor stability at the interface or the tendency to form type II microemulsion. Modification of their structure by elongating their tails or changing their composition by adding or substituting chemical groups did not improve their performance. The Gemini-type surfactant showed promising results. We saw that a tail exclusively composed of carbon atoms could form an oil in water emulsion while a tail composed of polyethylene oxide favored oil in water emulsion. Following the simulation results, we modified the design by creating a molecule containing a combination of both carbon and polyethylene oxide groups. These modifications resulted in a molecule that showed optimum properties for a type III microemulsion making it a candidate for synthesis and further testing. This investigation shows that it is now possible to exclusively use computational chemistry simulation to create and screen for surfactant structures that will show optimum properties for cEOR without the need for extensive experimental testing. This protocol effectively reduces the time needed to design and test novel chemicals ten-fold, opening the door to faster chemical development in the Oil and Gas industry for applications ranging from oil production to transport and demulsification.