Reservoir Quality Analysis of Sandstone & Carbonate Rock Types

Introduction

This Blackbird training course is aimed at giving oil industry geologists a detailed introduction to the study of sandstone and carbonate rock-types in terms of reservoir quality. Reservoir quality analysis permits to identify the main depositional, provenance and diagenetic controls on the evolution of the poro-perm characteristics of sandstone and carbonate reservoirs (e.g. evolution of porosity vs. burial depth, mineralogical content and diagenetic environments). Examples from sandstone and carbonate oil/gas reservoirs (i.e. current East & West Africa basins) are also taken into consideration.

Course Objectives of Reservoir Quality Analysis
of Sandstone & Carbonate Rock Types

• Understand what are the different types of sandstone hydrocarbon reservoirs and their main controls on reservoir quality
• Understand what are the different types of carbonate reservoirs and their main controls on reservoir quality
• Be able to differentiate depositional, provenance and diagenetic markers of analysed sandstones and carbonates
• Be able to integrate and interpret poro-perm data vs. stratigraphy and regional geology (e.g. well correlations)
• Understand the main rock-based methodologies of analysis applied to reservoir quality studies
• Be conversant with the concepts of Rock typing and petrophysical comparison of cuttings and core samples

Reservoir Quality Analysis
of Sandstone & Carbonate Rock Types Course Outlines

Day 1
Introduction to Siliciclastic Reservoirs

• Siliciclastic rocks, sediment texture, detrital components
• Sandstone classification, minerals and source areas, depositional markers
• Sandstone composition, provenance, and tectonic settings
• Grain size analysis and digital image analysis
• Depositional environments, provenance, and reservoir quality
• Definition of matrix and pseudo-matrix
• Compaction and authigenic components
• Diagenesis of siliciclastic rocks, diagenetic environments & sequences
• Concepts of SEM, EDAX and XRD analyses, chronology of diagenesis
• Concepts of CL analysis on the distribution of quartz cement

Day 2
Reservoir Quality Analysis of Sandstone Rock-Types

• Reservoir quality definition and methods of work
• Cementation and reservoir quality
• Porosity types in sandstones
• Porosity-permeability analysis and interpretation, cuttings TS descriptions/analysis tied to wireline logs
• Estimating subsurface reservoir quality from outcrop samples
• Rock Typing, petrophysical assessment of cuttings, rock typing analysis of cuttings petro-types
• Rock Typing classification scheme(s) as from oil industry methodologies
• Rock Typing and reservoir quality
• Diagenetic controls on reservoir quality and porosity variation with depth & stratigraphy

Day 3
Introduction to Carbonate Reservoirs 

• Introduction of carbonate reservoirs
• Components of limestones, carbonate depositional environments and facies, calcite vs. aragonite seas in the geological record
• Matrix and authigenic components, taxa vs. mineralogy, classification of limestones
• Rates of carbonate production, microfossils, paleoenvironmental markers, carbonate platform facies, carbonates and sea level changes, regional carbonate petrography vs. stratigraphy
• Carbonate diagenesis: Neomorphism, compaction, marine diagenesis, meteoric diagenesis, burial diagenesis
• Diagenetic markers, carbonate diagenetic stages
• Dolomite textures and stable isotope signatures

Day 4
Reservoir Quality Analysis of Carbonate Rock-Types

• Carbonate diagenesis and reservoir quality, dolomite texture vs. petrophysics, dolomitization models, limestone vs. dolostone reservoir quality
• Porosity in carbonate rocks, classification schemes, petrophysics by carbonate rock-types, porosity preservation, visual estimation of porosity vs. point count porosity
• Controls on reservoir quality, rock fabric and wireline logs, porosity evolution vs. geological time
• Carbonate reservoir models and reservoir quality, porosity vs. petro-facies
• Rock typing concepts, petrophysical assessment of cuttings, rock typing classification schemes, Rock typing datasheets, rock typing and reservoir quality
• Emphasis on single well or multi-well studies, with regional reservoir quality correlations

Day 5
Examples of Siliciclastic and Carbonate Reservoirs and Practical Work

• Cretaceous siliciclastic reservoirs from north, east and west Africa
• Italian carbonate reservoirs, Angolan Pre-Salt (Pre-Aptian) reservoirs, Kenyan carbonates, Indonesian carbonate reservoirs, New Zealand carbonate reservoirs, Oman reservoirs
• Practical session in polarizing microscopy on: Texture, composition, diagenesis, porosity, and reservoir quality of siliciclastic and carbonate rocks-types
• Visual estimation of sandstone and carbonate porosity. Porosity of core samples (point count porosity) and point count porosity vs. CA data
• Differences in the controls on reservoir quality between sandstones and carbonates
• SEM/EDX/XRD images and plots
• References on petrography/petrophysics/reservoir quality for self-training sessions