Geomechanical Modeling of Stimulation Induced Stress Change for Casing Deformation Analysis

Speaker:  Roberto Wagner Alvarado

Location:  Chesapeake Energy Maple Room

                    6100 N. Western Ave

                   Oklahoma City, OK 73116

Dates: October 16, 2024
Time: 11:30 am - 1:00 pm
Cost: $25 Members $35 Non-members (lunch included)

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Abstract
Casing deformation occurs during hydraulic fracturing of unconventional plays, which often compromises
wellbore integrity, compromises operations, and leads to a decrease in productivity and economics. In the
Austin Chalk Formation, South Texas, casing deformation was commonly observed in the form of
horizontal contraction and vertical elongation of casing. Finite element models of hydraulic stimulation
run on a 3D geomodel built from seismic and well data were used to better understand some of the
mechanisms responsible for the deformation. After investigation of these mechanisms, a plan was
developed to mitigate the impact of casing deformation for a multi-well co-development.
A 3D geomodel was built as the framework for geomechanical simulations, which includes the matrix
properties, faults, and other discontinuous elements such as dipping beds and discrete fracture networks,
as described from a suite of image logs and seismic data. Three-dimensional stresses were initialized on
this model from extrapolation of 1D stress profiles derived from calibrated wellbore sonic data and were
used as initial conditions for hydraulic stimulation modeling. Sensitivities were run for different
stimulation designs (e.g., changing rate, volume, and cluster spacing) to test the effect on stress. In
addition, a high-resolution near-wellbore geomechanics model was implemented to investigate the
magnitudes and directions of stimulation-induced stress changes and implications for casing failure.
This investigation identified a spatial correlation between the occurrence of fractures, faults, and/or
bedding planes and casing deformation. Simulations suggest that in the presence of these structural
elements, casing deformation may result from fault reactivation and bedding-plane slip induced by
elevated horizontal stresses near hydraulic fractures. These findings align with fault and bedding
interpretations from seismic and borehole image logs, validated through casing caliper analyses. The
kinematics of fault reactivation implied by the models were calibrated with observations from casing
deformation and microseismic. Stress changes inferred by the models, in conjunction with seismic,
geosteering, and image interpretations, helped establish a mitigation strategy for future developments.
Casing deformation is a widespread problem in unconventional plays that can negatively affect both
operations and production. This paper demonstrates how a model-based approach can be used to
understand the potential causes of casing deformation and explore how sensitive such failures are to
different completion parameters. When properly calibrated, the model can be used to evaluate prevention
and mitigation scenarios before drilling and completion. Sensitivity testing on completion parameters will
also help quantify the risk of any given strategy. While this paper establishes a workflow to evaluate the
role of stress and structures on casing deformation to mitigate its impact in the Austin Chalk Fm., this
novel workflow is applicable to the development of other unconventional reservoirs

Bio: 

Geoscientist with over 20 years of experience in reservoir characterization, modeling, and field development across
diverse geological settings, including deltaic to deep marine deposits and both conventional and unconventional
reservoirs. Roberto’s industry collaboration has gone from exploration to mature field development, both onshore and
offshore. His career includes 17 years with TOTAL Energies across multiple global regions, followed by 4 years at
Chesapeake Energy as a Geoscience Advisor. Currently, he serves as the Subsurface Manager at XGS Energy, leading
geothermal resources evaluation, exploration, and feasibility studies. He has authored or coauthored around 18
publications and delivered international presentations on topics ranging from integrated modeling and field development
to structural geology and geomorphology.

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