Deep-Sea Drilling Through Cold-Water Coral Carbonate Mounds (ESF-CARBONATE): Drilling Campaign Results and Relevance to the Hydrocarbon Industry

Andrew J. Wheeler¹, Andre Freiwald², Tim Freudenthal³, Dierk Hebbeln³, Rudy Swennen⁴, Tjeerd van Weering⁵, Henk de Haas⁵, and Boris Dorschel^1
1Geology & Environmental Research Institute, University College Cork, Cork, Ireland
²Institute of Paleontology, University of Erlangen-Nuremberg, Erlangen, Germany
³MARUM - Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany
⁴Dept. Geography-Geology, Catholic University of Leuven, Leuven, Belgium
⁵Royal NIOZ, Texel, Netherlands

Cold-water coral carbonate mounds form common features at intermediate water depth on the European, African and American continental margins. They can be several hundred metres tall and more than a kilometre across. Features are both exposed at the seabed and buried within upper seismic sequences. They offer potential as hydrocarbon reservoirs with evidence of secondary porosity through dolomitisation noted. Exposures on land are rare with most information on internal properties coming from shallow cores and one borehole through one mound (the Challenger Mound - IODP Exp. 307). The ESF-CARBONATE project aims to increase our knowledge of the mound internal properties through drilling complete sequences through a number of mounds in differing environmental settings revealing the diversity of internal structures and properties.

Deep-sea drilling of cold-water coral carbonate mounds was undertaken at various sites on the Irish continental margin (Aug. 2008). A desktop study identified a range of carbonate mound provinces and potential drill targets based on existing information and multibeam echosounder coverages. A pre-drilling site survey was conducted in October 2007 with the acquisition of high resolution seismics, box-cores, piston cores, video tows and monitoring of seabed environmental dynamics using the BoBo lander platform. A number of drill targets were then identified.

Complete core sequences through carbonate mounds down to a maximum depth of 85m were collected using the remotely operated, seafloor mounted drilling platform MeBo with preliminary results presented here.

As well as internal mound properties and diagenetic processes, CARBONATE will also study palaeoenvironmental records, generate mound initiation and development models and quantify carbonate budgets.

AAPG International Conference and Exhibition, Cape Town, South Africa 2008 © AAPG Search and Discovery