geology of carbonate and sandstone reservoirs
Course Description
SCOPE AND PURPOSE OF THE COURSE
This course for geologists, geophysicists, and engineers is designed for professionals who have some experience with reservoir geology. goal of the class is to sharpen your skills at predicting the locations of potential reservoirs, diagnosing the different types of reservoirs (depositional, diagenetic, and fractured), and applying that knowledge to cost-effective exploration, development, and improved recovery programs.
COURSE PLAN
• Discuss fundamental (first order), derived (second order), and tertiary (third order) rock properties and how they are related to reservoir properties.
• Discuss reservoir properties including saturation, capillarity, capillary pressure, and fluid recovery efficiency. Discuss how those reservoir properties are related to 1st, 2nd, and 3rd order rock properties and how they influence reservoir productivity.
• Review the types carbonate depositional platforms (ramps, shelves, and isolated platforms), the depositional environments that occur on each platform type, and the facies characteristics of each platform type.
• Discuss ideal depositional successions (depositional models) for each type of carbonate platform and sandstone succession/facies with special emphasis on the most common depositional successions found in both reservoir types.
• Compare traditional lithostratigraphy with sequence stratigraphy and discuss the applications of sequence stratigraphy in exploration and development.
• Review carbonate and sandstone diagenesis – diagenetic environments, processes, and products. Discuss ways to recognize diagenetically altered reservoirs and interpret their origin and distribution in the subsurface.
• Brief overview of fractured reservoirs, emphasizing the properties that distinguish fractured systems from depositional and diagenetic systems and focusing on methods for analysis of fractured carbonate reservoirs.
• Selected problems will be given as time permits.
• Days 4 & 5 are “workshop” days
Discussions (‘lectures’) will begin at 8:00 or 8:30 am last for about 1 hour to 1-1/2 hours. We will take 10 to 15 minute breaks between lecture sessions and 1 or 1-1/2 hour lunch breaks each day, depending on what your management desires.
Note: This schedule of discussions covers an extensive and wide-ranging array of topics. It is a very ambitious schedule for a 3-day program; consequently, there may not be sufficient time for in-class problem solving or for extensive classroom discussions, particularly on those topics covered in Day III
Audience
Geologists, Geophysicists, petrophysicists and Reservoir Engineers
Prerequisites
Basic knowledge of Applied Petroleum Geology
Course Schedule
| 1 | • Introduction and organizational plan classroom lectures. • Overview of sandstone and carbonate reservoir geology • Significant differences between carbonates and siliciclastics and how the differences influence methods of interpretation. • Fundamental rock properties: texture, constituent composition, and sedimentary structures – the foundations for rock classifications and environmental interpretations. • Classification of detrital and reef carbonates. • Classification of terrigenous sandstones. • Derived properties: Porosity and porosity classifications. • Permeability and its relationship to porosity in carbonate and sandstone reservoirs • Tertiary rock properties as reflected in typical borehole log data for carbonates and sandstones. Electrofacies and e-facies mapping. • Reservoir (petrophysical) properties: saturation, wettability, capillarity. • Carbonate pore characteristics and values for Archie m, n, and a exponents. • Sandstone pore characteristics and calculations of Sw. • Microporosity in carbonates and clay in sandstones – impact on Sw calculations |
| 2 | • Review of capillarity, and capillary pressure. • Geometry of mercury capillary pressure curves in carbonate and sandstone reservoirs. • Class Problem 1: Given the capillary pressure curves from different rocks, explain which ones are good reservoirs and which may be seals. Capillary pressure characteristics of flow units, baffles, and seals. • Converting mercury-air to oil-brine values • Evaluating height of oil column and seal efficiency • Class problem 2: Calculate h for conditions to be given in class. • Mercury withdrawal efficiency and reservoir recovery efficiency – factors to consider. • Carbonate Depositional Platforms and Depositional Successions • Platform types – ramps and shelves – and their standard depositional successions. • Dunes, tidal flats, lagoons, barrier islands, shallow subtidal, slope break, slope, and basinal successions • Lithostratigraphic and chronostratigraphic correlation compared. • Sequence stratigraphy: Carbonate vs siliciclastic systems. • Risks involved in correlating subsurface facies with only wireline log data • Depositional systems in siliciclastics |
| 3 | • Detailed presentation on carbonate reservors with diagenetic porosity • Diagenetically enhanced pore systems: How to identify and characterize reservoirs with hybrid and diagenetically enhanced pore systems • Pore systems reduced by diagenetic processes: How to identify the type of diagenesis and incorporate reservoir zones with reduced porosity into reservoir characterization plan. • How diagenitically enhanced and reduced pore types influence petrophysical characteristics of reservoirs • Checklist for characterization of diagenetic reservoirs in carbonates : Characterization of fractured reservoirs • Detailed discussions and presentations on mechanical properties of rocks, stress strain relationships, and fracture mechanisms. • Identification of fracture types in tectonic terrains such as faulted and folded structures • Exploration and development tools for identification and characterization of fractured reservoirs of Types I, II, III, and IV of Nelson (2001) • Check list for characterization of fractured reservoirs
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| 4 | • Identification, description and characterization of depositional sequences in terrigenous sandstone reservoirs • Methods for predicting spatial distribution of sandstone depositional facies. • Review diagenesis in sandstone pore systems and how it influences petrophysical characteristics such as saturation, capillarity, and reservoir rock quality |
| 5 | • Introduction to petrophysical rock types in sandstone and carbonate reservoirs - log k/phi plots with and without facies, stratigraphic modified Lorenz plots, and introduction to 'Winland' type plots for reservoir analysis • Class teams to present synthesis of methods for reservoir characterization in carbonate and terrigenous sandstone reservoirs • Instructor summary of week's work on rock properties, petrophysics, depositional models, and reservoir characterization.
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Instructor
Dr. Wayne Ahr
Instructors may vary based on location and schedule.
Classes
No classes are currently scheduled for this course.
Add yourself to the waiting list
We will schedule a class for this course, when there are enough participants on the waiting list.
Course Provider:
Texas A&M University