This course will present an overview of current North American unconventional gas shales; depositional processes and how they relate to poro-permeability (including fracture properties) and lithology, fabric, mineralogy and organic geochemistry (including biomarkers); commonality of a sequence stratigraphic framework for gas shales and how to develop that framework; seismic response; and geomechanical properties of shales, with emphasis on ductile-brittle couplets at the sequence- to-bed scales. An integrated gas shale characterization workflow is provided. Limited exercises will be presented, with emphasis on selecting optimal target drilling of strata.
This course is designed for geologists, geophysicists and petroleum engineers who seek to gain a fundamental understanding of the geologic and related properties of unconventional Gas Shales from the pore to the regional scales. Gas Shales are becoming increasingly important energy resources worldwide, and sufficient data are becoming available to compare and contrast their properties for enhanced drilling and production. Shales are fundamentally different than their coarser clastic and carbonate counterparts in the stratigraphic record, and new concepts, techniques and applications are being developed to improve exploration and reservoir development.
Participants will learn the reasons for the rapid growth of unconventional reservoirs, their geologic and geophysical characteristics, exploration and drilling strategies, and special problems associated with their production. Petroleum engineers with some geologic background can also benefit from this course.
The various topics will be presented in a lecture format, and will be supplemented by exercises. The preferred method of teaching this course is using a ‘paperless’ format, whereby participants are required to bring a laptop to the class, and a CD will be provided with the entire set of lecture figures and exercises (which can be done in power point on the laptop screen). Specific topics covered in the course are listed below.
1. THE “MAGNIFICENT SEVEN” AND OTHER GAS SHALES: OVERVIEW.
2. WORKFLOW FOR INTEGRATED CHARACTERIZATION OF UNCONVENTIONAL GAS SHALES FOR IMPROVED HORIZONTAL DRILLING.
3. SHALE LITHOFACIES AND THEIR STACKING PATTERNS: PREDICTABLE STACKING OF LITHOFACIES INTO PARASEQUENCES.
4. MUD DEPOSITIONAL PROCESSES: HEMIPELAGIC/BIOGENIC ‘RAIN’, HYPERPYCNAL AND TURBIDITY FLOW, AND/OR TEMPESTITES? THE SIGNIFICANCE OF FLOCCULES FOR TRANSPORT AND DEPOSITION, AND FOR ROCK STRENGTH.
5. LAMINATIONS AND THEIR RELATION TO STRATIGRAPHY AND GEOMECHANICAL PROPERTIES OF SHALES. GEOMECHANICAL PROPERTIES ANALYSIS.
6. MINERAL COMPOSITION AS A FUNCTION OF LITHOFACIES AND IMPORTANCE TO PORO-PERM AND GEOMECHANICAL PROPERTIES; THE BRITTLENESS INDEX; COMPARISON OF ANALYTICAL METHODS FOR MINERAL IDENTIFICATION/QUANTIFICATION.
7. ORGANIC GEOCHEMISTRY OF GAS SHALES, WITH EMPHASIS ON RELATIVE HYDROCARBON POTENTIAL; USE OF BIOMARKERS FOR ENVIRONMENTAL DISCRIMINATION.
8. POROSITY AND PERMEABILITY: HOW GOOD ARE THE ANALYSES? DO PORO-PERM RELATE TO MINERALOGY, ROCK FABRIC, SPECIFIC ORGANIC/INORGANIC GRAIN TYPES AND/OR PARTICULATE ORGANIC MATTER? MICRO-CHANNELS AND MICRO-FRACTURES. FORMATION OF PERMEABILITY PATHWAYS IN GAS SHALES; DIRECT OBSERVATIONS OF OIL MIGRATION IN SHALES.
9. THE CONCEPT OF ORGANIC RICH-FRACTURE PRONE STRATIGRAPHIC COUPLETS AT THE MICRO- TO REGIONAL SCALES: EVIDENCE FROM HIGH RESOLUTION SCANNING ELECTRON MICROSCOPY (FESEM), OUTCROPS, CORE, LOGS, AND MICRO-SEISMIC.
10. SEISMIC MAPPING OF PARASEQUENCES AND WHY THAT IS IMPORTANT.
11. SEQUENCE STRATIGRAPHY OF UNCONVENTIONAL GAS SHALES: COMMONALITY OR COINCIDENCE OF STRATIGRAPHY AMONG DIFFERENT GAS SHALES? TOWARD A GENERAL SEQUENCE STRATIGRAPHIC MODEL FOR GAS SHALES AND APPLICATIONS TO EXPLORATION AND RESERVOIR DEVELOPMENT.
12. QUANTIFYING FRACTURE PATTERNS IN OUTCROP FOR APPLICATION TO SUBSURFACE WELLS; FRACTURES AT THE MICRO- TO SUBREGIONAL SCALES AND THEIR CAUSES.
13. A PLAN FOR STRATIGRAPHIC PLACEMENT OF HORIZONTAL WELLS.
1. DRILLING, COMPLETION AND STIMULATION TECHNOLOGIES
- Horizontal well drillingTechnical
- Multi-stage hydraulic fracturing
- Micro-seismic monitoring
2. RESERVOIR ENGINEERING
- Laboratory measurements of shale gas storage and transport properties
- Gas-in-place calculations
- Gas transport calculations
- Pressure transient regimes in hydraulically-fractured horizontal wells
- Formation linear flow modeling
- Pressure transient analysis
3. FUTURE DIRECTIONS
- Environmental considerations in developing shale gas reservoirs
- Enhanced shale gas recovery
Lecture and exercise material is supplemented with integrated case history information on the Barnett Shale, from which the instructor has considerable experience.