Petroleum Geomechanics

Who Should Attend

Geologists, geophysicists, drilling engineers, reservoir engineers, exploration supervisors and managers concerned with:

• wellbore stability;
• fracture stimulation;
• reservoir drainage patterns;
• naturally fractured reservoirs;
• overpressures;
• fault seal integrity, or;
• image log interpretation.

About The Course

Petroleum geomechanics is concerned with the contemporary (also known as in situ) stresses in the subsurface and their influence on a very wide range of petroleum exploration and development-related problems. In situ stresses control issues as diverse as wellbore stability and fault reactivation/seal breach. This course covers the necessary fundamentals of rock mechanics, the origin of stresses in the subsurface and how in situ stresses can be constrained from wellbore data. The application of in situ stress data to critical problems in exploration and development is a focus of the course. There are detailed case studies on optimum development of a naturally fractured reservoir and on wellbore stability.

At the end of the course attendees will be able to use routinely collected and specialized data to constrain in situ stresses, and will be able to apply in situ stress data to exploration and development-related issues. Attendees will be able to address questions such as:

• How can I predict fault seal integrity prior to drilling?
• In what direction should a well be deviated in order to intersect natural fracture-enhanced permeability?
• What deviation directions can be successfully fracture stimulated?
• Why should injector wells be aligned in the minimum horizontal stress direction?
• Given our previous experience in vertical wells, will deviated and horizontal wells in this area be mechanically stable?
• What are the minimum and maximum mud weight envelopes for stability?

Case studies will be presented from the North Sea, Australasia and SE Asia. The topic requires a multidisciplinary, team approach to problem-solving with input from geology, geophysics and engineering. A basic knowledge of geology, geophysics and drilling practices is assumed. Individuals from any of these areas will benefit from exposure to the multidisciplinary nature of the topic. All the topics are addressed in lecture format and re-inforced with practical exercises.

Course Content

• Introduction
  Course structure and significance of in situ stresses in petroleum exploration and development.
• Basic Rock Mechanics
  The stress tensor, units (densities, gradients and pressures), stress and strain, stresses and forces, resolving stresses and forces on a plane, Mohr's circle of stress, states of stress, modes of rock deformation.
• Basic Fault Mechanics
  Friction, cohesion, Coulomb failure, Mohr failure, Griffith failure, fault/fracture meshes, Andersonian classification of faults, pore pressure, effective stress and rock failure.
• Stress in the Crust
  Plate tectonics, regional stresses, local stresses, stress rotations, World Stress Map, examples of stress studies from Western Europe/North Sea, Australasia and SE Asia, reference state of stress, tectonic stress.
• Determining In Situ Stresses from Oilfield Data
  The stress tensor, principal stresses, overburden stress, horizontal stress orientation, borehole breakouts, drilling-induced tensile fractures, image logs, vertical and deviated wells, horizontal stress magnitudes, formation integrity, leak-off and hydraulic fracture tests, fracture gradient relations, frictional limits on stress.
• Applications of In Situ Stress Data
  Interpreting recent tectonic style, structural permeability, optimum development of naturally fractured reservoirs (fracture susceptibility diagrams), predicting fault reactivation/seal breach (FAST mapping), hydraulic fracture stimulation (heterogeneous lithologies, deviated wells, fracture twisting and high stress reservoirs), deviated and horizontal wellbore stability (stable drilling directions and mud weights – avoiding borehole breakout and lost circulation).