Geodynamikk og Bassengstudier

Masterprosjekt vår 2019 ved GEO - David Peacock

Relationships between bed thickness and joint frequencies


Project description

Joints are important conduits for fluid in rock, so understanding their distribution is important to the geology of fractured reservoirs, with application to petroleum, geothermal energy, hydrogeology, and CO 2 sequestration. It is commonly thought that joint spacing is proportional to bed thickness in sedimentary rocks (e.g., Narr, W., Suppe, J., 1991. Joint spacing in sedimentary rocks. Journal of Structural Geology 9, 1037-1048). Such analyses focus on one set of joints (the master set), measuring frequencies perpendicular to the
orientations of the joints. Joints, however, form networks of fractures consisting of at least two sets. It is the connectivity of these networks that controls the permeability of the joints, and the connectivity is described using their geometry and topology. Whilst the relationship between joint spacing and bed thickness has been used to give information about the
mechanics of the master joints, it is not particularly useful for understanding permeability through the fracture network.

This project aims to gain a better understanding of connectivity and therefore permeability related to fracture networks by determining the relationships between bed thickness and the number of intersection points (nodes) of joints per unit area. This, and the
trace lengths of joints per unit area, will improve understanding of the controls on permeability of joint networks.


That there is:
(1) a relationship between bed thickness and the number of joint intersection points per unit area, and
(2) a relationship between bed thickness and the trace lengths of joints per unit area.

Measurements will be made of joint patterns (especially number of joint intersections per unit area, and of trace lengths of joints per unit area), and results will be plotted against bed thickness.

Field work

The project requires one week of fieldwork on the Devon and Cornwall coast, UK, between Hartland Point and Crackington. This will involve photographing joints on bedding planes and measuring bed thicknesses. The photographs will be used to measure joint patterns, and data will be analysed using Excel spreadsheets and ArcGIS.

Proposed course plan during the master degree:

GEOV221 Karstgeologi og karsthydrologi (10)
GEOV251 Videregående strukturgeologi (10)
GEOV260 Petroleumsgeologi (10)
GEOV272 (10 stp) – Seismisk tolking
GEOV352 Petroleumsgeologisk feltkurs (5)
GEOV362 Pyrenneene feltkurs i sedimentologi og tektonikk (5)
Enten: AG-322 (UNIS) Fold and Thrust Belts and Foreland Basin Systems (10)
Eller: AG-336 Rift Basin Reservoirs: From Outcrop to Model (10 ECTS)