Modelling Complex Hydraulic Fracturing in Naturally Fractured
Formations and Integration to Production Optimization Workflow
Olga Kresse*, Xiaowei Weng, and Charles Cohen
Pressure Pumping and Chemistry Product Group, Schlumberger,
Sugar Land, TX, USA
Accepted for publication on 8th April 2014
Advances in horizontal drilling and new practices in hydraulic
fracturing have changed the paradigm of shale reservoirs in the
last decade. Multi-stage stimulation has become the norm for
unconventional reservoir development. Nevertheless, completion and
stimulation engineers still face serious challenges due to the
complex physics involved during hydraulic fracture propagation
including hydraulic fracture interaction with natural fractures,
stress shadow effects, and proppant transport in complex fracture
networks.
A recently developed unconventional fracture model (UFM) is able
to simulate complex fracture network propagation in a formation
with pre-existing natural fractures. A method for computing the
stress shadow from fracture branches in a complex hydraulic
fracture network based on an enhanced 2D Displacement Discontinuity
Method (DDM) with correction for finite fracture height is adopted.
The influence of stress shadow effect from the hydraulic fracture
network generated at previous treatment stage on the hydraulic
fracture network propagation and shape at new stage is also taken
into account. The fracturing interaction model incorporates
important elasticity, fluid and fracture mechanics related
phenomena as well as the influence of fluid properties on the
crossing behavior of hydraulic fractures at natural fractures.
After the fracturing simulations are performed with the UFM
model, an automated unstructured gridder is used to generate fine
grids surrounding the resulting complex fracture networks necessary
for accurate reservoir simulation. This grid is then passed to a
numerical reservoir simulator to run the production simulations and
accurately model multiphase reservoir flow around complex hydraulic
fracture networks. Integration of the accurate complex hydraulic
fracture model and reservoir simulator provides a powerful tool for
optimizing completion design to maximize production. The details of
the hydraulic fracturing model (UFM), its integration into the
fracturing-to-production simulation workflow, and the results from
the production simulations will be presented.
Keywords: hydraulic fracture, modeling, production,
optimization
