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Geomechanics involves analyzing the way rocks stress, including how and when faults will develop, as well as the mechanics of soil and rock (i.e., studying the mechanical behavior of geological materials). As defined by, geomechanics is the study of how subsurface rocks deform or fail in response to changes of stress, pressure and temperature. 

OilField Geomechanics LLC (OFG), a provider of geomechanics engineering consulting services, was founded in 2014 by Dr. Marisela Sanchez-Nagel and Dr. Neal Nagel—partners in business and life—with a focus on HSE protection. 

Dr. Marisela Sanchez-Nagel and Dr. Neal Nagel
Dr. Neal Nagel (left) serves as chief engineer and is responsible for the engineering quality of OFG's  products, and Dr. Marisela Sanchez-Nagel (right) serves as company president, performing engineering duties while also reaching out to potential clients and partners for integrated projects. (Source: OilField Geomechanics)

"We have more than 65 years of combined industry experience, with operators and service companies, on projects spanning the globe," Sanchez-Nagel said. "Our strength comes from our solid foundation and experience in geomechanics, applied in a direct, practical approach tailored to support our clients, whether that be at the management level, for an engineering team or simply a turnkey project. We deal with near-wellbore and field-based geomechanics applications such as wellbore stability, hydraulic fracturing, solution cavern stability, caprock integrity and compaction/subsidence challenges."

Looking at the current issues being faced by companies, she mentioned that keeping scientific and engineering experience and knowledge in place continues to be a challenge.

"This knowledge and experience is absolutely critical to support ongoing decision-making and future investments," she said.

OFG offers training courses in geomechanics, both client-specific and open courses through professional societies and training companies, and it provides litigation and expert witness support in the areas of geomechanics and related engineering topics.

In an exclusive interview with E&P, Sanchez-Nagel shared insights on current trends, challenges and the future of geomechanics technology. 

E&P: How has geomechanics technology evolved over the past year or two? What has worked and/or not worked?

OilField Geomechanics LLC
Dr. Marisela Sanchez-Nagel

Sanchez-Nagel: While there have not been any real revolutionary changes in geomechanics-related technologies in the last couple of years, there continue to be evolutionary changes driven by computing capabilities and the application of AI and machine learning in the better and/or more rapid evaluation of data.

From our perspective, we’ve also seen the geomechanics business gain a renewed interest in rock mass behavior, as opposed to laboratory-scale behavior, as large-scale field laboratories/experiments and new monitoring techniques have (re-)revealed the critical role of the rock mass behavior, including rock fabric, during, for example, hydraulic fracturing operations.

In addition, we find that very often projects are data poor in the key components of our analyses (i.e., stresses, mechanical properties and pore pressure), and more sophisticated computing tools—requiring more sophisticated data—do not improve the engineering solutions. AI and machines learning are, however, providing some ways for detecting real-time events that can improve our response to a particular challenge when the proper geomechanical analyses and models are available to support these decisions.    

E&P: How is OFG helping address challenges faced in the upstream sector?

Sanchez-Nagel: As a service provider, we can address two specific challenges: knowledge/experience retention and availability and local-scale or project-scale (as opposed to corporate-scale) economics.

Our training courses, for example, focus on challenging common practice and accepted 'wisdom' using science and engineering fundamentals in order to explain why something works (or not!) so that it can be predictive rather than prescriptive. In addition (obviously), our training courses also serve to transfer knowledge and wisdom to a next generation of scientists and engineers but also, hopefully, build an appreciation and excitement for geomechanics engineering.

OilField Geomechanics

OilField Geomechanics
OilField Geomechanics course offerings include fundamentals of geomechanics, geomechanics data, geomechanics for unconventionals, drilling geomechanics (borehole stability) and hydraulic fracturing in unconventionals. (Source: OilField Geomechanics)

From the consulting side, our challenge is conveying that, while our efforts cost money, geomechanics engineering can add appreciable value by finding means to cut costs or by finding means to improve revenues via increased production, increased reserves and increased recovery.

E&P: Can you share any recent case study details?

Sanchez-Nagel: We have, for example, an ongoing project in which water injection is critical for pressure maintenance and recovery. The optimization of hydraulic fracturing design to keep the fractures in the reservoir and address the changes in stresses as a result of depletion are critical. These have to be analyzed at a field-scale, including complex geological structures and reservoir quality/properties variability, in order to optimize the development plan in an economical way.

OilField Geomechanics
OFG numerical model results for zipper fracs pumped from two horizontal wells (plan view): (left) Shmin perturbations (stress shadows) after three hydraulic fractures (HFs); (right) corresponding induced shear stresses in the rock at the tip of the hydraulic fractures. The model shows the complexity of the stress field induced and the corresponding frac lengths during the zipper frac operation. (Source: OilField Geomechanics)

E&P: What emerging trends are you seeing in the geomechanics space?

Sanchez-Nagel: From a geomechanics perspective, a lot of interest is now focused on:

  1. Triggered seismicity;
  2. Long-term, underground carbon storage (CCS);
  3. Underground storage of hydrocarbons AND hydrogen; and
  4. Geothermal develops.

In fact, a critical part of the last three items is their potential related to the first item (triggered seismicity).

These efforts, to varying degrees, are putting additional focus on the uncertainty in basic geomechanics data, particularly stress measurement. There appears to be a nascent trend regarding the development of new tools for stress measurements and renewed interest in applying these tools in the field.

E&P: Where do you see the future of geomechanics technology headed? What other improvements can be made or are needed?

Sanchez-Nagel: Engineering in the subsurface is largely about dealing with uncertainty. A significant future direction for geomechanics will be in reducing these uncertainties (in order to improve our decision-making) through better data analyses (e.g., AI), better integration of the data captured in real time from smart systems (e.g., AI and machine learning) and integration of data over extended, life-of-project, periods of time.

While we don’t see it going away entirely, we also think that the current fervor over the development of new and more data-intensive computational models in the universities will begin to wane. Too often these tools go unused, either because they are unproven or because their data requirements make them impractical.  

 OilField Geomechanics
Coupled geomechanics/fluid flow analyses are needed when determining, for example, the effect of reservoir depletion on the stresses, for different type of engineering applications. An efficient way OFG has tackled this problem is by using powerful geomechanics simulators and sophisticated flow simulators and transferring data between them at different time snapshots (one-way, two-way or iterative coupling). (Source: OilField Geomechanics)

E&P: How are you supporting operators aiming for a net-zero future?

Sanchez-Nagel: We are actively supporting our clients with geomechanics technology for underground carbon storage projects as well as the development of carbon-neutral geothermal efforts. 

E&P: What are OFG's 2021-2022 goals?

Sanchez-Nagel: Continue to provide training courses and expand our project participation around the world with interesting projects in unconventional reservoirs, hydraulic fracturing and underground storage geomechanics. Expand our participation in solution salt mining and continue growing in litigation cases in which our expertise is critical.