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Deepwater corals (Lophelia) was identified in the vicinity of the location of the exploration well Pumbaa on the Norwegian Continental Shelf where a drilling operation was carried out by the GDF SUEZ E&P Norge AS (GDF SUEZ). When drilling in sensitive areas, it is a requirement from the Norwegian authorities that the operator shall monitor the drilling operation. Possible impacts on the corals were simulated prior to the drilling operation. In addition, monitoring of the discharges during drilling was carried out in order to document effects on the corals. The paper considers a comparison between measured and simulated discharges of drill cuttings and mud to the sea on the Pumbaa field in the Norwegian Sea. The actual monitoring program is presented in a separate paper on this conference (Moskeland et al. 2012). The main objective of the monitoring was to assess effects from the drilling activities on the corals south (and nearest) of the drilling location. The monitoring program included measurements of current, turbidity and sedimentation, as well as sampling of sediments from the seafloor. The data collected in the monitoring program turned out to be useful as well to validate numerical models for simulations of the discharges. In the present case, corals are located close to the drilling site, and the simulation tool could then be validated for prediction of potential exposure of the corals. The actual comparison between model simulations and measurements is carried out by comparing the actual depositions of barite on the sea floor. In addition, turbidity recordings close to the sea floor are compared with simulated concentrations of particle matter at the locations of the turbidity recordings. Good correspondence is obtained between model results and measurements on the occurrence of events of particle matter present in the water column at selected locations. A good similarity is found between measured/simulated depositions of barite at the sea floor, and measured/simulated concentrations of particle matter in the water column. Use of the model validated will strengthen the operator's ability to predict exposure (and consequently potential damage) on corals (and other biological resources) prior to the drilling operation. The operator may then obtain an "early warning" on exposure (potential damage). Measures can then be initiated to eliminate or reduce environmental impact. |
