DBR Distinguished Speaker Series 2015-2016
"New Asphaltene Nanoscience and Its Impact on Reservoir Characterization"
New Asphaltene Nanoscience and its impact on Reservoir Characterization Crude oils consist of gases, liquids and solids, the asphaltenes. The gas and liquid constituents of crude oil are chemically well understood and their theoretical frame work can be satisfactorily treated by cubic equations of state as shown explicitly by Professor D.B. Robinson and coworkers many years ago. In contrast, the asphaltenes have been grossly misunderstood precluding any theoretical treatment of asphaltene gradients in reservoirs. In recent years, asphaltene science has undergone a renaissance with many of the advances being subsumed in the “Yen-Mullins model” which codifies the dominant molecular and nanocolloidal structure of asphaltenes. Recent validation of all aspects of this model will be reviewed and include studies in mass spectroscopy, direct molecular imaging, NMR relaxometry and spectroscopy, interfacial science and oilfield studies. In particular, asphaltene molecular architecture continues to be debated and will be a central focus herein. With this asphaltene nanoscience sufficiently resolved, the ‘gravity’ term is now understood enabling the development of the industry’s first equation of state for asphaltene gradients, a modified polymer theory, the Flory-HugginsZuo (FHZ) EoS. This new science is being linked with new measurement technology Downhole Fluid Analysis which allows reservoir fluid gradients to be measured routinely. Many reservoir complexities are now being addressed with this integrated approach. Application of the FHZ EoS to a complex oil column in a large oilfield is established over a lateral distance of 100 kilometers. Equilibration of reservoir fluids indicates reservoir flow continuity as proven in many case studies (a billion dollar concern in deepwater). Stair-step, discontinuous asphaltene distributions portend reservoir compartmentalization, which can destroy reservoir economic value. New case studies show nonequilibrated asphaltene gradients are associated with baffles to fluid flow which can decrease production rates by 10x. Other transients (in geologic time) accurately modeled by the FHZ EoS plus diffusion include a reservoir undergoing diffusion and biodegradation for 50 million. Several mechanisms of tar mat formation are now resolved addressing a long-standing enigma in the oil industry. The combination of new asphaltene science and new downhole measurement technology is producing an explosion of applications.
Dr. Oliver C. Mullins is a Science Advisor to executive management in Schlumberger. He is the primary originator of Downhole Fluid Analysis (DFA) which is now ubiquitously utilized in well logging around the world. Dr. Mullins also leads an active research group in petroleum science leading to the Yen-Mullins model of asphaltenes. This model enabled Mullins and coworkers to develop the industry’s first equation of state for asphaltene gradients in reservoirs, the FHZ EoS, by modifying a polymer solution theory. His current interests include utilizing the new DFA technology and new asphaltene science to perform novel reservoir evaluation. He has won several awards including the SPWLA Gold Medal for Technical Achievement, SPE Distinguished Membership Award and two Schlumberger Gold Medals. He authored the award-winning book “The Physics of Reservoir Fluids: Discovery through Downhole Fluid Analysis” and has been Distinguished Lecturer 4 times for SPWLA and SPE. He has co-edited 3 books and coauthored 13 chapters on asphaltenes and related topics. He has co-authored 230 publications, ~½ on petroleum science, ~½ on applications, and has co-invented 96 allowed U.S. patents. There are 9,700 citations to his work on Google Scholar. He is Editor of “Petrophysics”, Fellow of two professional societies and is Adjunct Professor of Petroleum Engineering at Texas A&M University. His hobbies include skiing and biking.