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Validation and application of fully-coupled finite element hydraulic fracture models

This work describes the validation and application of new 3D finite element models for a diverse set of oil & gas problems involving fluid-driven fractures. Applications include drilling wellbore integrity lost returns, drill cuttings disposal, long-term water injection, and hydraulic fracture stimulation.

The models were developed using new capabilities of a commercially-available finite element software package. The models include both cohesive elements (mesh conforms to pre-defined fracture orientation) and extended finite elements (fracture geometry evolves independent of the finite element mesh). Advantages and disadvantages of each approach will be described. The models were validated through comparisons with published semi-analytical solutions for extreme values of rock and fluid properties and leak-off conditions. A comprehensive suite of large-scale laboratory experiments were also conducted and models were used to replicate conditions and results of these experiments. Larger finite element models were then constructed and used to demonstrate applicability to a broad range of realistic oil & gas problems, including 3D multi-zone and multi-fracture problems with large length scales and long-time scales enabled by high-performance parallel computing systems.

The models show excellent agreement with published analytical solutions for a broad range of rock and fluid properties and fracturing conditions. These numerical models also show very good agreement with laboratory experiments for a similar range of conditions. The models scale up from lab to well scales and have shown good applicability for a diverse set of realistic and challenging oil and gas problems.

Most hydraulic fracture models fall into the categories of fast-running but with simplified physics or complex physics but computationally impractical for full-scale commercial applications. These models have been applied at full commercial time and length scales but also provide for full representation of the complex physics of hydraulic fracturing, as demonstrated by the comprehensive validation with analytical solutions and laboratory experiments.

Author(s):

Matias Zielonka    
ExxonMobil Upstream Research Center
United States

Kevin Searles    
ExxonMobil Upstream Research Center
United States

Jorge Garzon    
ExxonMobil Upstream Research Center
United States

Jing Ning    
ExxonMobil Upstream Research Center
United States

Nikolay Kostov    
ExxonMobil Upstream Research Center
United States

Pablo Sanz    
ExxonMobil Upstream Research Center
United States