GEOL40690 Fractured rock modelling

Academic Year 2023/2024

This 2.5 credit module addresses the challenge of working with fractured reservoirs and aquifers. Quantitative methods used to characterise fault and fracture systems from borehole and map data, and the construction of fractured rock geomodels will be discussed. Choice of modelling technique ranges from their explicit representation in discrete fracture network models, to their inclusion as volume-averaged properties in continuum or dual-property models and depends on both fracture characteristics and the problem being addressed.

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Curricular information is subject to change

Learning Outcomes:

By the end of the module students should be able to:
Describe the key properties of fractures and fracture systems using terminology appropriate for different application areas.
Describe the different ways that fractures and fracture properties are represented in subsurface models.
Assess the suitability of different fracture modelling approaches as a function of geological scenario and geo-engineering requirement.

Indicative Module Content:

The module consists of a couple of introductory lectures, a day’s fieldwork, and a three-day student driven modelling exercise. An end-of module exam covers material from all of these components.

Lecture 1: Fractured rocks
What is fractured rock: Fractures and stress regimes; Failure envelope and fracture types; Joint sets, spacing, association with folds, Joint swarms; Stratabound and non-stratabound fractures; Shear fractures (faults); Compactive shear bands and stylolites. Modelling Fractures as baffles and conduits: Caine’s conceptual model of the permeability structure of fault zones; Managing low permeability faults in flow models; Managing high permeability fractures in flow models. What are Naturally Fractured reservoir or aquifers: Type 1, Type2 and Type3 reservoirs; Local and reservoir-scale heterogeneity.

Lecture 2: Fractured rock characterisation and modelling
Primary and secondary fracture characteristics. Characterisation from 1D data. Fracture frequency, intensity and dimensionless intensity: Orientation correction of intensity, Fracture intensity and length distribution, Fracture spacing characterisation. Fracture connectivity: Percolation thresholds and dimensionless intensity, Influence of fracture network topology and clustering. Fracture system modelling for flow: Stratabound and non-stratabound system.

Fieldwork

A day will be spent characterising fractures with the granite outcrops at Bullock Harbour (Dublin).

Discrete fracture reservoir modelling

This student-driven exercise is designed to provide experience in modelling workflow definition and execution. The class will be split into pairs of students who must built a 3D discrete fracture network model based on data collected during the fieldwork, for the purpose of assessing the permeability structure of the fractured granite. The students must assess the capabilities of the recourses available against other possible software and make recommendations for how your study could be improved, given other resources and more time. Three full days will be timetabled for the modelling. Assessment of this component will include both teamwork and individual components and will be based on a presentation summarising the work undertaken, as well as a demonstration of the model.

Student Effort Hours: 
Student Effort Type Hours
Autonomous Student Learning

24

Lectures

6

Practical

12

Field Trip/External Visits

8

Total

50

Approaches to Teaching and Learning:
The module has a strong focus on self-guided learning through data analysis modelling and presentation. 
Requirements, Exclusions and Recommendations

Not applicable to this module.


Module Requisites and Incompatibles
Additional Information:
Students must be registered to F181 MSc in subsurface characterisation and geomodelling


 
Assessment Strategy  
Description Timing Open Book Exam Component Scale Must Pass Component % of Final Grade
Examination: written examination Unspecified No Standard conversion grade scale 40% No

40

Presentation: Discussion, presentation and demonstration of the discrete fracture network model. Unspecified n/a Standard conversion grade scale 40% No

40

Project: Field data collection and analysis Unspecified n/a Standard conversion grade scale 40% No

20


Carry forward of passed components
No
 
Resit In Terminal Exam
Summer No
Please see Student Jargon Buster for more information about remediation types and timing. 
Feedback Strategy/Strategies

• Feedback individually to students, on an activity or draft prior to summative assessment
• Feedback individually to students, post-assessment

How will my Feedback be Delivered?

Ongoing practical work will be discussed with students individually and collectively whist it be being performed during the scheduled practical classes. Post-assessment feedback will be provided as sought.

Name Role
Dr Conrad Childs Lecturer / Co-Lecturer
Timetabling information is displayed only for guidance purposes, relates to the current Academic Year only and is subject to change.
 

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