II. ENVIRONMENTAL IMPACTS AND RISKS EVALUATION OF OFFSHORE DRILLING
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II.2.2 Application of LCA to offshore exploration drilling
II.2.2.1 Definition of the scope and objectives of the study
This study focuses on the life cycle analysis of offshore oil exploration drilling in the coastal
waters between Skikda and Annaba, within the perimeter bounded by national company
Sonatrach in the figure 11. The primary objective of this analysis is to assess the potential
environmental impacts associated with offshore exploration drilling in this area. It also involves
comparing scenarios simulated to determine their environmental impact scores and thus to
identify areas for improvement of the system and the choice of the best scenario.
The analysis focuses on a generic system that is an exploratory drilling well, with an average
depth of approximately 3000m, including the water column according to the bathymetry of this
area. The defined functional unit is therefore to drill a well at sea with an average depth of 3000
m with 500m3 of Water-Based sludge (WBM) and 2000m3 of Oil-Based sludge (OBM).
The system limits consist of successive sections of the 36”, 26”, 17 ½"; 12
1/4 " and 8
1/2 " well in
addition to the treatment of liquid and solid discharges as drilling waste (fluids and cuttings).
Three offshore well drilling scenarios have been defined based on the chemical composition of
the drilling fluids and the options for managing the drilling waste. These options took into
account the treatment processes available onshore: Centrifugation, Stabilization-Solidification
and Thermal Desorption.
The figure 18 below shows the generic diagram of the modeled system limits and the drilling
waste options (Fig.18).
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49
II.2.2 Application of LCA to offshore exploration drilling
II.2.2.1 Definition of the scope and objectives of the study
This study focuses on the life cycle analysis of offshore oil exploration drilling in the coastal
waters between Skikda and Annaba, within the perimeter bounded by national company
Sonatrach in the figure 11. The primary objective of this analysis is to assess the potential
environmental impacts associated with offshore exploration drilling in this area. It also involves
comparing scenarios simulated to determine their environmental impact scores and thus to
identify areas for improvement of the system and the choice of the best scenario.
The analysis focuses on a generic system that is an exploratory drilling well, with an average
depth of approximately 3000m, including the water column according to the bathymetry of this
area. The defined functional unit is therefore to drill a well at sea with an average depth of 3000
m with 500m3 of Water-Based sludge (WBM) and 2000m3 of Oil-Based sludge (OBM).
The system limits consist of successive sections of the 36”, 26”, 17 ½"; 12
1/4 " and 8
1/2 " well in
addition to the treatment of liquid and solid discharges as drilling waste (fluids and cuttings).
Three offshore well drilling scenarios have been defined based on the chemical composition of
the drilling fluids and the options for managing the drilling waste. These options took into
account the treatment processes available onshore: Centrifugation, Stabilization-Solidification
and Thermal Desorption.
The figure 18 below shows the generic diagram of the modeled system limits and the drilling
waste options (Fig.18).