UKOOA drill cuttings
IRIS played a significant role in both phases of the UKOOA Drill Cuttings Initiative. The first phase of the UKOOA initiative aimed at assessing all available and relevant existing information through a suit of studies.IRIS took part in three such studies concerning toxicity of cuttings piles, cuttings pile degradation and bioremediation. ( See reports RF - 1999/310, RF - 1999/350, RF - 1999/351)
In the second phase of the programme IRIS led two larger projects and participated in a third one. IRIS was responsible for characterisation of the two cuttings piles at Beryl A and Ekofisk 2/4 A (Task 1). IRIS also led the task 3 which has the long title: “Initiate comparative time series data on factors determining future pile volume from representative oil based mud (OBM) and water based mud (WBM) cuttings piles”. Task 3 activities included establishing biodegradation rates, erosion rates, bioturbation and survival and colonisation rates of selected organisms. Such data were later used as input data for a model aiming at predicting the long-term fate of cuttings piles. Task 5a, led by AEAT, addressed the possibility of establishing bioreactors on the seabed for bioremediation of the drill cuttings.
Task 1: The characterisation task included planning and carrying out a field survey to collect material for several other projects (tasks), sampling of deep core samples for chemical analysis and sampling for biological and physical characterisation.
The offshore survey at Ekofisk and Beryl was carried out in September 2000. Several tonnes of material were collected using different types of sampling equipment such as box-corers, vibrocore and grab. The vessel used, Edda Freya from Østensjø Rederi, is a supply vessel highly suitable for the task, which was fortunate as the survey was completed in a season with variable weather conditions.
Chemical analysis of a comprehensive set of parameters were carried out, including metals, THC, PAH, PCB, NPDs, decalines, TOC and TON. In addition pH, redox potential (eH) and sulphide was measured. Analyses of mineralogy and radioactivity (NORM) were also carried out. Samples were further screened for hormone effects (endocrine disruption). Bioavailability and leaching of metals were further investigated by sequential extraction and sub-sequent analysis. ( report RF - 2001/092; without appendix).
Task 3: The task 3 activities were conducted in collaboration with SINTEF and ERT. Studies of aerobic and anaerobic biodegradation was conducted jointly by IRIS & SINTEF ( report RF - 2001/217; without appendix ), bioturbation and colonisation of cuttings material by selected lug-worms (Capitella capitata) and mussels (Abra alba) were carried out at IRIS with assistance of ERT. See reports ( RF - 2001/218; appendix and RF - 2001/219; appendix ). Erosion studies were carried out by SINTEF. The sub-task findings of task 3 is summarised in a joint report.( RF- 2001/220; )
Contact person:
Grethe Kjeilen-Eilertsen
Grethe.Kjeilen@iris.no
http://www.oilandgas.org.uk/issues/drillcuttings/index.htm
Print page 