2014 Rice Oil & Gas HPC

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It is challenging to develop bulk materials that exhibit high compliance, high strength and high recoverable strain because of the intrinsic trade-offs among these properties.1 A high compliance in a single phase material usually means weak interatomic bonding and thus low strength. One of the urgent applications of high compliance, high strength materials is in well cementing used in hydraulic fracturing and generally all oil and gas wells where the cement is placed in the annular gap between the drilled formation and the steel casing. Despite the critical role of wellbore cement to prevent zonal isolation and secure casing, cement failure is still a serious problem with enormous socioeconomical impacts (e.g. 2010 oil spill disaster in the Gulf of Mexico, ground water contamination via cement failure in hydraulic fracturing). Wellbore cement frequently fails in a brittle mode due to the downhole pressure, or the formation loading (creep). Given the extreme downhole conditions, to date there is neither a unified understanding nor a reliable methodology to divert this brittle fracture mechanism – a lack of knowledge, which can costs billions of dollars with huge environmental impacts. In this talk, I will describe a novel multiscale computational method to develop a high compliance, high strength wellbore cement where the high compliance assures ductility to accommodate the pressure buildup, and the high strength prevents premature failure. First, I will describe how the state-of-the-art computational atomistic modeling techniques can be used to decode the basic molecular structure of a series of cement hydrate compositions. Second, combinatorial techniques will be utilized to tune the molecular features, self-assembly and aggregation of cementitious materials, thereby providing more coherent microstructure. Third, modern optimization methods such as level sets and phase field methods (based on solving partial differential equations) will be used to simultaneously maximize the ductility and strength of the microstructure via modulating topology and multi-phase heterogeneity of the materials. Together, these multi-scale multi-paradigm methods enable to rapidly screen several fundamental physical properties at extreme conditions (e.g. HTHP, corrosive environments, etc) to find the best-in- class microstructure candidates for accelerated well cementing material discovery. Finally, I will discuss various benefits of such modern computations techniques (e.g. guiding the synthesis of the proof-of-concept high compliance, high strength prototype) with an outlook towards substantially minimizing conventional trial-and-error experiments.