Fine-grained sediments act as top seals to many petroleum accumulations. On the other hand, the huge volumes of petroleum accumulated above thick sequences of fine-grained sediment in most petroleum systems are a testament to the capacity of cap rock sequences to transmit petroleum on geological timescales. The flow properties of cap rocks thus represent a significant exploration uncertainty, not just in terms of seal capacity but also in terms of predicting the rates and mechanisms of petroleum leakage. The same concepts are directly relevant to the safe geological storage of CO2.

The overarching objective of the Caprocks project is to integrate seismic, petrophysical, rock mechanical and geochemical data to produce methodologies with which to (a) quantify seal risk and (b) define the rates, mechanisms and pathways by which petroleum migrates through kilometre-scale sequences of fine-grained sediments. Within these broad aims we integrate studies of cap rock properties at seismic to pore scale, including fundamental research on:

• Defining the 3D architecture of mudstone sequences: the “Caprock Cube”. Integrates data obtained at core, wireline and seismic scale and seeks to quantify the impact of sedimentary heterogeneity on fluid flow
• Log interpretation of mud-rich sediments
• Pore scale properties of mud-rich sediments: e.g. capillary pressure, wetting state, permeability and relative permeability
• Strategies for upscaling and modelling fluid flow through caprocks on a range of spatial scales, and in situations where discontinuities (faults, fractures, injectites) occur
• Petroleum leakage: evidence, rates and mechanisms

Much of our work is based on case studies provided by industrial sponsors. Current data sets are from deep water West African and North African settings, where significant petroleum accumulations occur but where there is also evidence of leakage through geological time.

The academic team comprises personnel from Newcastle, Cardiff, Leeds and Heriot Watt Universities with expertise in seismic interpretation, mudstone petrophysics, geosciences, special core analysis and fluid flow
modelling.

Current sponsors are: Anadarko, BG, BHPBilliton, BP, ConocoPhillips, ENI, Petrobras, StatoilHydro, Total and Chevron