Carbonate Reservoir Characterization

Course Description

This carbonate reservoir characterization course focuses on the analysis of carbonate depositional textures and the subsequent diagenetic modifications as the main controls on the pore system evolution, heterogeneity and complexity. The intricate inter-relationship of the depositional and burial history can be unravelled to allow the prediction of reservoir facies, and hence, aid reconstruction and development of three-dimensional reservoir models. This course demonstrates the value of understanding pore system evolution as a part of large-scale volumetric assessments and the development of carbonate reservoirs.

Reservoir quality in carbonate successions is often defined by the storage capacity, flow potential (ie. porosity and permeability respectively, measurements that are often acquired during conventional core analysis) and connectivity of pores (recorded as the pore-throat radius distributions during special core analysis). The interplay between these quantifiable factors (including sample-scale heterogeneities) is inevitably linked to the original depositional characteristics of the carbonate sediments, together with their susceptibility to post-depositional diagenetic alteration, which results in the ultimately complex pore system. Therefore, the classification of individual pore types will be detailed in this course, with their primary depositional or secondary diagenetic origin being discussed in context with sedimentological and stratigraphic models in order to underpin their spatial relationships and potential connectivity. In addition, the characterization of micrite textures will be discussed to illustrate their impact on the microporosity, factors that are particularly important to consider in tight unconventional reservoirs.

The depositional controls on reservoir properties that will be taken into consideration in this course include the texture, grain size, clay and matrix content as well as the type and quantity of allochems. The relationship between dissolution processes that result in an enhancement of the pore system, cementation processes that reduce the pore volume and the resultant connectivity and fluid flow pathways will be assessed to constrain the dominant diagenetic controls on the reservoir properties. In addition to this, the process of dolomitisation will be scrutinised in order to determine if and how this process enhances and/or reduces reservoir properties.

Integrating the key controls on reservoir quality within the sedimentological framework enables the establishment of a conceptual reservoir architecture model, which can be used to assess and predict the vertical and lateral variations in porosity and permeability at the reservoir and/or field scale.

This course outlines how to conceptually build a reservoir architecture model, which in turn can be used to aid reservoir modelling.

This course will be accompanied by a series of in-class exercises, which will emphasize the integration of the various datasets, providing participants with experience in carbonate reservoir characterization.

Course Objectives

Upon completion of the course, participants will be able to:

• Identify the different pore types, their interconnectivity and hence the impact on permeability;
• Determine how specific sedimentological parameters and diagenetic process impact reservoir quality;
• Understand sample heterogeneity and its impact on reservoir quality data;
• Upscaling of reservoir quality data to aid prediction at the field scale.

Course Outline

The course will be organised into three sessions:

Part A: Reservoir quality analysis - What it is and how to approach it

• Definition of reservoir quality;
• How to characterise reservoirs.

Part B: Pore types and connectivity

• Concepts and definitions;
• The carbonate pore type classification(s);
•  Permeability and pore-throat radius distributions;
• Manipulating reservoir quality data;
• Introduction to advanced reservoir quality tools.

Part C: Controls on reservoir quality

• Sample heterogeneity;
• Sedimentological controls;
• Diagenetic controls;
• Reservoir architecture construction.

Each section will be accompanied by examples from case history exercises.

Participants’ Profile

This course is designed for petroleum geologists, geoscientists, petrophysicists and engineers involved in exploration and production of carbonate plays.

Prerequisites

Although previous knowledge on carbonate sedimentology is not necessarily required, participants should have some knowledge of geology.

About the Instructor

Laura Galluccio (Ph.D.) is one of Badley Ashton’s UK-based senior carbonate reservoir geologists with an interest in carbonate petrography and sedimentology. She specialises in sedimentology, diagenesis and reservoir quality characterization of limestones and dolomites in both conventional and unconventional reservoirs. She has wide experience in the Middle East, the USA, Europe and Africa. The projects she has been involved in cover a wide range of depositional environments from shallow to deeper water carbonates. Laura received his BSc, MSc and PhD at the University of Naples (Italy), with her PhD conducted in conjunction with Shell Italy. As an effective communicator and with a proven track record of excellent client care, past roles include Team Leader of the Carbonate Group, and local Business Manager and Consultant Geologist based in PDO’s offices, Muscat. Since her appointment as Regional Manager in August 2017, Laura oversees business activity in the Middle East, Africa and Asia, supported by regional Operations and Portfolio Managers. Laura’s other research interests include sedimentology and sequence stratigraphy of ancient and recent carbonate platforms and the characterization of diagenetic processes affecting carbonate sediments with integration into the regional framework and influence on the pore system. She is currently involved in research on the diagenesis and pore volume assessment of Hyamm Formation in Oman in collaboration with the Ferrara University and Sultan Qaboos University, as well as a project focused on the role of hydrocarbons emplacement for calcite precipitation, in collaboration with Newcastle University. Laura has undertaken teaching of geological mapping, petroleum geology and reservoir quality evaluation at both BSc and MSc levels, while co-supervising a variety of BSc and MSc carbonate research projects.

Catherine Breislin (Ph.D) is a Reservoir Geologist working in Badley Ashton’s UK-based Carbonate Team. She specialises in carbonate sedimentology, diagenesis and reservoir quality analysis using a range of techniques in both conventional and unconventional reservoirs. Her work to date has focused on investigating the controls of depositional facies, platform architecture, and structural development on basin-scale diagenetic fluid flow and its impact on reservoir quality. Her project work has covered a wide range of depositional environments from shallow to deeper water carbonates.

Catherine received her MESci at the University of Liverpool (UK), and PhD at the University of Manchester (UK), with her PhD conducted in conjunction with Shell and the British Geological Survey. Catherine has a strong background in field geology, core-logging, carbonate sedimentology and geochemistry, and is proficient in conducting spatial integration of multiple data sets. She also has experience in lab-based mineral identification analyses, where she has developed best practice methodologies and workflows. While co-supervising an MSc carbonate research project at Manchester University, Catherine has undertaken teaching of carbonate sedimentology, geological mapping, petroleum geology and reservoir quality evaluation at both BSc and MSc levels.