Oil and Gas
Oil and Gas | Unconventional Resources
Business Impact: Improving recovery and volume in horizontal wells by optimizing multistage hydraulic fracturing operations in the most productive intervals.
The application of geomechanical knowledge has become critical to the successful drilling and completion of unconventional plays. This course presents the basics of oil-field geomechanics (including stress/strain, pore pressure, rock behavior and wellbore applications) and then focuses on the geomechanical characterization and modeling of unconventional reservoirs.
Duration and Training Method
This is a classroom or virtual classroom course comprising a mixture of lectures, discussion, case studies, and practical exercises.
Participants will learn to:
- Assess in-situ stresses with field, log and laboratory data.
- Build and calibrate 1D and 3D geomechanical models as starting points for geomechanical analyses.
- Assess the specifications of a geomechanics evaluation and design and QC a geomechanics testing program.
- Assess the key shale geomechanical properties needed to determine the efficiency of hydraulic fracturing.
- Gauge the effect of operational parameters in different geological/ geomechanical scenarios on hydraulic fracturing success.
- Assess the differences, advantages and limitations of available modeling tools for hydraulic fracturing.
- Determine the value and effectiveness of multi-well completions.
- Determine the value of microseismic data and the effects of geology, geomechanics, and pore pressure on the microseismic response.
- Gauge the role of natural fractures and weak planes on the overall behavior during stimulations and decide which type of analysis is needed in each case.
- Assess the role of stress shadows and determine when they are critical factors.
The first portion of the course will address the fundamentals of oil-field geomechanics, including stress, mechanical properties and failure. Common near-wellbore and reservoir-scale geomechanics applications will be introduced. The second part of the course will focus on the characterization of unconventional reservoirs (heterogeneous rock masses with the presence of discontinuities and weakness planes) and present the tools and models that can be used to optimize single- and multi-well hydraulic fractures in these intervals. Examples from a variety of unconventional plays will be discussed.
Part 1: Geomechanics Fundamentals
Module 0. Introduction to Unconventional Geomechanics
- What makes a good play – geomechanics point of view
- Unconventional Play scenarios
- What is geomechanics? Definitions, history, relevance
Modules 1 - 2. Principles of Stress and Strain - Field Stress Measurements
- Basic of stress-strain and Mohr circles - application of natural fractures
- Effective stress concepts, role of pore pressure
- Field stress variations, structural effects
- Stresses around boreholes
- Stress determinations
Module 3. Pore Pressure Evaluation
- Basic concepts and causes of overpressure
- Pore pressure analysis – Eaton, Bowers’, NCT, effective stress methods
- Analysis workflow
- Challenges in unconventional, field examples
Modules 4 – 5. Mechanical Rock Behavior
- Mechanical properties, elasticity plasticity, poroelasticity, viscoelasticity
- Failure in rocks, failure criteria
- Influence of faults and fracture, anisotropy
- Laboratory testing, measurements, interpretation
- Use of logs for mechanical properties, calibration, correlations
Module 6. Geomechanical Modeling and Workflows
- Concepts and tools
- 1D, 2D and 3D models
- Geomechanics workflows in unconventionals
Part 2: Geomechanics for Unconventionals
Module 7 - 8. Hydraulic Fracturing Fundamentals
- Basic, objectives, parameters
- Frac containment, net pressure
- Injection testing, DFITs
- Horizontal wells
- Perforating, Proppants – 100 mesh and proppant transport,
- Fracturing fluids
- Role of natural fractures. Injection zone selection
Module 9. Stress Shadows - Multi-stage Multi-well
- Mechanics of stress shadows
- Effect on multi-stages and clusters
- Multi-well stress shadows
- Tip shear stresses, Modeling examples
Module 10. Rock Fabric Characterization
- Description and quantification of rock fabric attributes – cores
- Mechanical behavior, hydraulic behavior, testing in unconventionals
- Stresses - critically stress fractures and hydraulic conductivity
- Geometry and spatial occurrence, DFN models.
- Examples of evaluation in unconventional plays
Module 11. Shale Geomechanics
- Unconventional shale plays – shale types – challenges, critical issues
- Geological scenarios for completions
- Geomechanics of interfaces – HF interaction with interfaces, effect of fracture toughness
- HF models: traditional and advanced models
- Shale properties static and dynamics examples from different plays – elastic parameters, time
- dependency, frictional properties
- Shale and Shale like behavior – mineralogic content, shale and flow
Myths to debunk – brittleness, complexity, SRV and microseismic, sand volume per lateral length
Module 12. Hydraulic Fractures (HFs) and Natural Fractures (NFs)
- HFs propagation with NFs – effect of NF orientation
- Dual HF propagating in a fractured media
- Pressure Diffusion – coupled effects – stimulation benefits
- Interaction HF – NF - crossing rules.
- Influence of NF characteristics – Dense vs sparse DFN, stress anisotropy, NF connectivity,
- parametric studies. Modeling examples.
- Influence of operational parameters, effects of fluid viscosity, injection rates – injection time,
- Influence of the stress field and in-situ pore pressure on HF behavior.
- Microseismicity response with anisotropic stresses – dry and wet MS events. Effect of initial aperture
- of the NFs.
Module 13. Depletion – Refracs
- Depletion effects on HFs, depletion and in situ stresses.
- Parent-child evaluations, Cluster efficiency, drainage volumes
- Frac hits - types.
- Microseismic depletion delineation, Cube evaluations
- Refracturing – candidates, case histories, lessons.
- Geomechanics of refracs.
- Refracs economics, refrac activity, examples.
- Refracs methods, engineered refracs.
Module 14. Multi-well completions
- Zipper fracs, stress perturbations, induced shear around zipper fracs
- Interaction of HFs, overlapping HFs, models
- Zipper fracs stress shadows.
- Effect of multiple well completion in fractured rock mass – sheared fabric – friction angle effect,
- geometry of zipper fracs. Effect on fabric stimulation.
- Sheared length, pressure diffusion.
Module 15. HF Monitoring and models (Extra session)
- Temperature Logs, strengths and weaknesses, procedures. Effect of wellbore and completion.
- RA logging procedures, strength and weaknesses, tracer applications
- Microseismic monitoring – MS as a geomechanics issue. Events, field data, MS imaging, passive
- seismology, triggered or induced seismicity, array design, surface vs downhole, source mechanisms,
- SRV from MS and drainage volume.
- Tiltmeters- direct fracture monitoring, measurements, patterns, cases.
- DAS/DTS Basics, production estimations, cluster efficiency, integrated analysis.
- HF Models - advanced models fundamentals, input data, 2D models, pseudo (planar) 3D, Cell/Grid
- based models, lumped pseudo 3D, Fully 3D, HF reservoir simulators.
Who Should Attend and Prerequisites
The course is intended for geoscientists, reservoir engineers, drilling engineers, and completions engineers currently working in unconventional resources and for managers seeking to understand geomechanics.
Dr. Neal Nagel, Chief Engineer at OilField Geomechanics LLC based in Houston, has 30+ years of industry experience, having started as a college professor in 1987 and then joining Phillips Petroleum in the 1989. He has taught extensively since the mid-1980s via open and in-house training courses as well as through SPE and AAPG courses. Nagel worked with ConocoPhillips for nearly 20 years and has been an industry consultant and testifying expert witness in geomechanics and completions since 2009. Nagel, an SPE Distinguished Lecturer in 2004 and again in 2017, is also currently chairman of the Geomechanics Technical Section of SPE, a member of the SPE RDD committee, was chief editor of the 2010 SPE Monograph on Solids Injection, has served on the SPE Drilling and Completions Committee, and is a past local SPE section officer. He is a well-known expert in the geomechanics of Unconventionals and has given many invited SPE, AAPG, HGS, SEG, and SPWLA presentations. Nagel has also authored or coauthored more than 50 technical papers, with 20+ related to Unconventionals, including a keynote presentation at the 2014 SPE HFTC.
Affiliations and Accreditation
PhD University of Missouri-Rolla - Mining Engineering
MSc University of Missouri-Rolla - Mining Engineering
BSc University of Missouri-Rolla - Mining Engineering
N250: Evaluation Methods for Shale Reservoirs
N437: Geomechanics for Unconventional and Tight Reservoirs
Dr. Marisela Sanchez-Nagel, who is currently the President of OilField Geomechanics LLC, has more than 25 years of industry experience, having worked with PDVSA, the Venezuelan national oil company, for 15 years as a geomechanics specialist in areas such as reservoir and drilling. Dr. Sanchez-Nagel worked at GMI, performing more than 25 projects in borehole stability, fault seal analysis and sand production evaluations around the world. She was responsible for opening the Itasca Houston oil and gas office and serving as President and GM for 7 years, mostly working in the geomechanics of unconventionals. Currently at Oilfield Geomechanics she works on 1D and 3D geomechanics modeling and its applications to oil and gas. She has taught numerous courses throughout her career in the USA and Latin America. Among her industry activities, Dr. Sanchez-Nagel is currently Director at the Geomechanics Technical Section for SPE, was an SPE Distinguished Lecturer in 2013 on the geomechanics of unconventional plays, and member of organizing committees for different workshops, forums and conferences SPE and ARMA. She has authored and coauthored more than 25 technical papers.
Affiliations and Accreditation
PhD University of Oklahoma - Geological Engineering
MSc Universidad Simón Bolívar - Geotechnical Engineering
BSc Universidad Central de Venezuela - Mining Engineering
N437: Geomechanics for Unconventional and Tight Reservoirs