Introduction to shale gas geomechanics – business drivers …
Basics of Rock Mechanics includes - concept of stress/strain; definition of elastic properties, Young’s modulus, Poisson’s ratio, bulk modulus, shear modulus, bulk compressibility; rock strength – UCS, tensile strength and shear strength; yield, failure and failure criteria
- shear and normal stress calculations,
- effect of pore pressure
Laboratory Rock Mechanics - testing geometries and interpretation of test results. Computation of mechanical properties; and strength parameters from logs; why difference between dynamic and static properties; converting dynamic to static, calibrating mechanical properties.
- Compute mechanical properties from logs
- Interpret and analyze mechanical core tests
- Calibrate mechanical properties
Understanding Earth Stresses includes - concept of principal stresses; are principal stresses always vertical and horizontal?; in-situ stresses - overburden stress, minimum and maximum horizontal stresses: magnitude and orientation; stress regimes – is vertical stress always the maximum?; pore pressure and principle of effective stress; estimating stresses from wire line logs; calibration of in-situ stresses; borehole breakouts, drilling-induced tensile fractures, use of image logs in understanding stress orientation and anisotropy; how does stress help orient wellbore and completions; stress measurement using mini-frac/LOT/MDT; basic definitions of fracture gradient, break down pressure, fracture propagation pressure, closure pressure and other terminologies used in LOT/XLOT.
• Compute stresses from logs and calibrate using mini-frac data
Pore pressure - Origins of pore pressure, methods for measurement, estimation of pore pressure in shales, equivalent depth methods, Eaton’s method, real-time approach for drilling
Wellbore Stability – Basics includes - state of stress around the wellbore; stress state & drilling hazard; what is wellbore failure and types of failures; failure criteria, and prediction of the mud weight window.
- Estimation of pore pressure using equivalent depth
- Compute stresses around a borehole
- Estimate safe mud weight window
Mechanical Earth Modeling includes - recommended data acquisition program for an effective geomechanics analysis; introduction to building Mechanical Earth Model (MEM): why and how is it used?; types of MEM, input data, deformation mechanisms; integrating log data, core data and field stress measurements in MEM.
Shale Anisotropy and Heterogeneity includes - characterizing shale from geomechanics perspective; shale anisotropy – micro-scopic to core to field scale; how to evaluate it?; evaluating TIV anisotropy, scratch testing and variation in mechanical properties in vertical and horizontal directions;
Anisotropy and Stress in Shales – anisotropic stress models; acoustic anisotropy; estimating anisotropic parameters using acoustic azimuthal anisotropy (Sonicscanner).
- Compute stresses using anisotropic mechanical properties
- Compare with isotropic stresses
Drilling through Shale includes - effect of intrinsic anisotropy, bedding planes and natural fractures; transversely isotropic and anisotropic models in wellbore stability analysis; geomechanical considerations for drilling high angle and horizontal wells through laminated shale..
Hydraulic fracturing and Shale stimulation - theory of hydraulic fracturing, how fractures are created/initiated, fracture growth; fracture height and width, preferential direction, vertical and horizontal fracs, and frac barriers; parameters controlling frac geometry; fractured reservoirs: influence of natural fractures on fracturing; frac fluid and proppant properties.
Introduction to Microseismics - hydraulic fracture performance evaluation; introduction to microseismic and hydraulic fracture monitoring (HFM); field examples on hydraulic fracturing and horizontal completions in shale gas reservoirs.
Interaction between natural and induced fractures – the effect of natural fractured formations on hydraulic fracturing
- Hydraulic fracture propagation in a naturally fractured formation
This course covers the necessary fundamentals of geomechanics including practical definitions of mechanical properties, anisotropy, heterogeneity and their influence on drilling and completions, critical elements in designing hydraulic stimulation and horizontal completions, and best completion practices. Throughout the course, field examples from shale reservoirs are shown to reinforce the geomechanical concepts.
This short course is intended for engineers, geoscientists, and technologists involved in exploration, drilling, completions and production in unconventional reservoirs.
4 years of Geoscience or engineering degree.