Process-Based Modeling of Natural Fractures in Carbonate Reservoirs

Abstract

Carbonate rocks are prone to early fracture development owing to syndepositional cementation, which can be overprinted by later burial and tectonic fracturing processes. Conventional stochastic fracture modeling approaches typically do not consider the physics behind fracture development and are solely dependent on statistical interpolation between well data that inherently undersamples fractures in the subsurface. Recent computational advances enabled the rise of more sophisticated finite-element and combined finite-discrete element models. Such numerical modeling can be utilized to build process driven fracture models that allows for interrogating parameters controlling the fracturing process, prediction in interwell areas, and accounting for heterogeneities in mechanical properties. This work showcases examples of process-based fracture models applied to several carbonate depositional settings. The primary objective of the showcased models is investigating atectonic syndepositional fracturing processes including differential compaction, but such modeling can also be applied to tectonic fracturing processes. The models require several inputs with various degrees of uncertainty including: (1) initial geometry of strata, (2) mechanical properties, (3) failure model, and (4) boundary conditions. Strategies on constraining inputs to process-based models are discussed. Knowledge of tectonic history, depositional settings, diagenetic history, and mechanical stratigraphy are essential in constructing geologically sound fracture models. The process-based modeling approach provides a fundamental understanding of fracturing processes and can be instrumental in improving subsurface fracture predictions in carbonate reservoirs.

AAPG Datapages/Search and Discovery Article #90370 ©2020 AAPG Middle East Region Geoscience Technology Workshop, 3rd Edition Carbonate Reservoirs of the Middle East, Abu Dhabi, UAE, January 28-29, 2020