Shaly Sand Petrophysics

Course Duration: 5 days, including lecture-based modules and hands-on exercises

Who Should Attend: Development and exploration geologists, geophysicists, petrophysics and log/core analysts, reservoir and drilling engineers, managers, and technical personnel

Course Summary: Too many wells have been and continue to be plugged and abandoned for lack of understanding the role of clay minerals, including their type, and their distribution on log analysis, with overestimation of Sw as a dominant theme. Participants will be exposed to the cutting-edge of shaly sand petrophysics, including modern 3D array resistivity tools, wireline and LWD log analysis, and so forth, with extensive practical exercises from diverse environments around the world.

Tentative Topics:

• Review of log interpretation techniques in clean formations
• The nature of shale and clay
• Clay/shale occurrence in reservoir rocks related to depositional environment and diagenesis
• Influence of clay/shale on petrophysical properties and log responses –Various methods of shale content evaluation
• Causes of low-resistivity, low-contrast in hydrocarbon bearing shaly-sand reservoirs and identification of pay zones.
• Integration of petrographic, core, and log data for evaluation
• Methods of shale content (Vsh, including Vlam) evaluation
• Petrophysical models for effective porosity and saturation determination
• Concepts of Archie parameters (m and n) as applicable for shaly sand petrophysics
• Electrical resistivity-based petrophysical models including Vsh corrections and dual-water (dual-electrical) model (benefits and short-comings)
• Prediction of permeability and producability from logs in shaly sands: Identification of bypassed pay
• Use of and integration of advanced logs and techniques—NMR, wireline (e.g. FMI) and LWD image logs, array induction tools (including 3D resistivity), LWD propagation resistivities (including azimuthal propagation resistivity) and modeling
• Laminated sequences and their effect of various log measurements
• Seismic interpretation and data integration, reserve estimation and techno-economic analysis
• Shale/clay influences toward reservoir and fault seal
• Geosteering and reservoir navigation within a shaly-sand system
• Case studies (global and domestic). Participants encouraged to bring in their own datasets.

General Outline:

• Welcome and Introduction
• General Concepts of Shaly-Sand Evaluation (occurrence of shales in stratigraphic systems; clay typing and distribution; porosity evaluation, including total versus effective porosity; methods of Sw determination and the effect of clays; petrophysical models)
• Data Integration for Shaly-Sand Evaluation (cuttings; core, including petrographic and special core analyses; log datasets; seismic evaluation)
• Nuclear Log Methods of Shaly-Sand Evaluation (including Vsh determination; cross-plot techniques and multivariate analysis; porosity evaluation; clay typing)
• Resistivity Log Methods of Shaly-Sand Evaluation (clean vs. shaly formation analysis; Sw models; resistivity anisotropy, inc. LWD azimuthal resistivity and wireline 3D array resistivity; laminated sequences)
• Case Study Analysis—deepwater Gulf of Mexico (in-depth hands-on project)
• Advanced Log Techniques (nuclear magnetic resonance; wireline and LWD azimuthal logs; integration within petrophysical models)
• Case Study Analysis—Dispersed versus laminated clays (in-depth hands-on project)
• Geosteering and reservoir navigation in shaly-sand reservoirs (real-time evaluation and facies analysis; LWD tools for reservoir navigation)
• Summary and Review