Hydraulic Fracture

Eng. Ricardo Ramos

Currently, there are no reliable techniques to measure fracture

geometries during or after the hydraulic fracturing process. Furthermore,

direct solutions of the underlying differential equations representing the

different physical processes occurring during fracturing are difficult to

construct, even in their most simplified forms. Therefore, the

development of a numerical simulator with accurate predictive capability

is of paramount importance.

Matias Zielonka

Exxon Mobil Upstream Research Company

Factors that influences

fracture behavior:

- Strong nonlinear coupling

- Flow of fracturing fluid

within the fracture

- Flow and seepage within

the pores

- Porous media deformation

due to pressurization

- Fracture propagation

- Weakness planes

- Pore pressure

Common assumptions in industrial

standard fracture softwares:

- Fractures assumed to be planar and

symmetric around the wellbore

- Fracture geometries are represented

by a few parameters

- Unbonded linear formation, integral

equation relates pressure and opening

- Linear elastic fracture mechanics

without pore pressure influence

- Leakage of fluids decoupled from

porous media deformation

- Without faults

- Without weakness planes

There are three main alternatives for fracture modeling in a finite element

framework:

- Cohesive elements

- XFEM

- Elemental damage theory with change in stiffness and permeability

(diffused fracture method)

Development approach in Argentina:

Cohesive elements with discontinuous Petrov Galerkin. Y-TEC.

Latest publications (ENIEF 2016):

“EFECTO DE FRACTURAS NATURALES SOBRE LA PROPAGACIÓN

DE UNA FRACTURA HIDRÁULICA EN LA FORMACIÓN VACA

MUERTA”

“DESARROLLO Y VALIDACIÓN DE UN SIMULADOR DE

FRACTURAMIENTO HIDRÁULICO ORIENTADO AL PETRÓLEO Y

GAS”

SIMULIA’s focus:

- Cohesive elements

- XFEM

Coupled equations:

Benchmark models:

Khristianovich-Geertsma-de Klerk (KGD)

Radial or “Penny – Shaped”

Available at reservoir scale