STABView Features

Types of Wells

• Vertical, horizontal, or deviated wells
• Offshore or onshore wells
• Single or multiple zone analyses
• Multi-branching wells

Drilling Instability

• Evaluate instability risks as function of ECD, EMW, BHP, SG mud density, over-or underbalance pressures
• 3D linear elastic models
• 2D elastoplastic models
• 3D passive shear failure initiation (borehole ballooning)
• Swab and surge pressure effects
• Underbalanced drilling features
• Calculate a mud density, EMW, ECD or bottomhole pressure required to achieve a tolerable instability risk, e.g., hole enlargement
• Calculate wellbore instability risks for a specified mud density, ECD, EMW or bottomhole pressure
• Calculate and display the drilling "mud weight window"
• Thermo-elastic effects due to steady-state conductive heat transfer
• Predict a profile of enlarged hole sizes for hydraulics optimization

Lost Circulation and Fracturing

• 3D elastic tensile fracture criterion
• Penetrating fluids (water, selected drilling and completion fluids)
• Non-penetrating fluids (cement, some muds)
• Thermo-elastic effects on fracture breakdown due to steady-state conductive or convective heat transfer
• Analyze packer and sleeve induced fractures
• Fracture toughness based breakdown criterion (after Morita)
• Specify a critical fracture plugging aperture
• Calculate points of hydraulic fracture initiation and display on borehole cross-sections and polar plots

Sand Production and Control

• 2D elastoplastic models3D linear elastic models
• Extent of horizontal well collapse (rubble fill percentage)
• Near-wellbore skin can be used as an input parameter
• Perforated, openhole, slotted liner, screen and expandable completions can be analyzed
• Cylindrical or hemi-spherical perforation cavities
• Input pressure drop across liners, screens and expandables
• First-order estimate of isotropic loading on liners, screens or expandables
• First-order estimate of borehole wall deformations.

In-Situ Stresses

• Biaxial stress state (2D models)
• Triaxial stress state (3D models)
• Correct stresses for reservoir pressure depletion or injection effects
• New poroelastic stress models for different reservoir shapes
• Rotated principal stresses, e.g., salt intrusion,  thrust fault stress regimes *

Planes of Weakness, Faults and Natural Fractures

• Account for the effects of ubiquitous, weak discontinuities on the risk of borehole collapse
• Mohr-Coulomb failure criterion
• Shear failure and slip tendency analysis for weak bedding planes, faults, natural fractures, cleats
• Re-opening pressure analysis for weak bedding planes, faults, natural fractures, cleats
• Display log-derived bedding planes, faults, natural fractures and cleats on polar plots*

Pore Pressure and Capillary

• Steady-state flow with pore pressure gradients into or out of the wellbore
• Capillary threshold pressure for OBMs and pseudo-OBMs
• Apparent capillary strength for weak, partially saturated sands
• Filter cake efficiency model for permeable sandstones
• Wall coating efficiency model for shales
• Effect of an instantaneous BHP change
• Fluid viscosity and permeability effects
• Formation damage and skin effects
• Steady-state non-Darcy flow effects for high rate gas wells and perforations
• Compressible fluid effects in the near-wellbore area
• Skin damage option for underbalanced drilling
• Biot or Terzaghi effective stress

Rock Failure Models

• 2D Elastoplastic strain-weakening
• Mohr-Coulomb Model
• 3D Linear Elastic Models
• Mohr-Coulomb
• Modified Lade
• Mogi-Coulomb*
• Non-linear Hoek-Brown
• Tensile fracture criteria
• Passive shear failure initiation
• Other Options:
• Time-dependent loss or gain of rock strength and elastic properties*

Borehole Stresses and Pressures

(As a function of radial distance)

• 3D Linear Elastic Models
• Principal stresses (s1, s2, s3)
• Normal stresses (sq, sr, sz)
• Shear stresses (trq, trz, tqz)
• Pore pressure
• 2D Elastoplastic Models
• Pore pressure
• Normal and shear stresses

Borehole Deformations and Strains

2D Elastoplastic Model for Isotropic Stresses

• Total strains
• Plastic strains
• Total radial displacements

Physico-chemical Effects

• Osmotic pressure model for reactive clay inhibition effects based on shale and mud activities (API RP13B specification)
• Handles many common oil-based and water-based drilling fluids
• Database of published shale water activities and membrane efficiencies for a variety of shales and fluids
• Drilling fluid activity calculator

Thermal Effects

• Steady-state conductive or convective heat transfer effects on fracture breakdown pressure
• Steady-state conductive heat transfer effects on 3D elastic borehole collapse risk
• Time-dependent thawing and hydraulics model for permafrost

Calibration and Validation Options

• Fix an acceptable BHP, drawdown pressure or mud density based on the performance of an offset well
• User-defined borehole breakout angle criterion
• Calibration options for borehole collapse and fracture breakdown

Quantitative Risk Analysis* (for 2009 release)

• Define input uncertainty with a variety of statistical distributions
• Include parameter correlations
• Minimize simulation runs with optimized Monte Carlo methods
• Cumulative probability mud weight window display
• Cumulative probability of yielding displayed on a borehole cross-section
• Statistical input and output in convenient data analysis reports

Back Analysis Assistant* (for 2009 release)

• Automatically back analyze and update a geomechanical model from observed hole enlargement on offset well caliper logs.

Database Links

• Link to ROCKSBank™, Weatherford Geomechanics Services worldwide rock mechanical and petrophysical properties database
• Link to the World Stress Map (Karlsruhe University)

Reports and Graphics

• Parameter sensitivity plots available for most stability and fracture models
• Tornado and spider plots for multiple input parameter sensitivities
• Scrollable "mud weight window" with re-scaling and zoom
• Color contoured polar plots for all 3D collapse and fracture models
• Export graphics to BMP and EMF file formats
• Clipboard support for copying and pasting output graphics and text
• Print to any Windows-supported device
• Single or multi-zone input and output reports
• Print preview capability
• Well plan and profile plots with color-contoured BHP, EMW, ECD, mud density, drawdown pressure, or other parameters
• Customizable color selection and pattern for lithologies
• Compare yielding size for different rock failure criteria
• New export file formats: JPG, GIF, RTF, XLS *

3D Wellbore Visualization

• Import well surveys and display in plan, profile and 3D views
• Visualize well trajectories in a rotatable 3D display with zoom and pan capabilities
• Display color-coded stratigraphic tops
• Display casing and/or liner profiles
• Color shaded wellbore for collapse or breakdown pressures
• View principal stresses as a function of radial distance
• Ability to move and position the view window as required
• Set the scale of the displayed wellbore radius
• No special 3D hardware required

Integration with Other Software

• Export text or graphics files
• Import well survey data
• Cut and paste annular pressure data from actual wells or wellbore hydraulics and multi-phase flow modeling software
• Run in parallel with casing design, pore pressure prediction, hydraulics and other wellbore design software

Units

• US oilfield and SI units
• High precision units for shallow wells and pipeline horizontal directional drilling (HDD)
• Customizable mixed units

Functionality

• Right-click drop-down menus on most screen output
• Solution algorithms optimized for rapid performance (most calculations in seconds)
• Designed to perform graphical sensitivity analyses
• Preferred user settings saved on exit
• Ability to cancel calculations in progress
• Run button to compute results only when required
• Toolbar buttons for most common tasks

Operating Systems

• Windows 2000/XP/Server 2003/Vista

Network / Deployment Options

• Can license for up to 3 PCs for a single USB security key
• Network version available with one or more concurrent seats
• Customized network configurations

Help and Documentation

• Real-time input data validation
• Comprehensive online Adobe Acrobat and hard copy user manuals
• Example files for all problem types (17)
• Comprehensive list of related technical publications and references
• Website and email support