Wind-Powered Water Injection in Offshore Oil Fields
Mohamed Mohamed Mahmoud Hanafy Mahmoud Abdaltawab (TU Delft - Electrical Engineering, Mathematics and Computer Science)
Michiel Zaaijer – Mentor (TU Delft - Wind Energy)
O. Leeuwenburgh – Mentor (TU Delft - Reservoir Engineering)
S.J. Watson – Graduation committee member (TU Delft - Wind Energy)
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Abstract
The developments in offshore wind offer new opportunities for the powering offshore oilfields in general, and offshore water injection processes in specific. On the other hand, building on the strength of the oil industry could enable a faster development of offshore floating wind turbine technologies (for use in deep and ultra-deep water oilfields), access to capital, political connections, global reach, and state of the art technical capabilities. Both the use of water injection to enhance oil recovery in suitable reservoirs and use of offshore wind technology to harness power are proven to be commercially and technically viable, each on its own. However, the integration of both systems has not been adequately investigated. This thesis investigates the potential of autonomous stand-alone wind-powered intermittent (fully wind powered, Scenario A) and cyclic water injection (wind and gas powered, Scenario B) schemes in offshore oilfields, specifically in heterogeneous layered oil reservoirs. The results obtained from analytical evaluations and numerical simulations of a 3D synthetic model demonstrates strong oil recovery performance, economic, and environmental feasibility, under modelled reservoir and economic conditions. Improved oil recovery is achieved by improved sweep of low permeable layers and previously poor swept areas. It is evident that reservoir performance favors the more intensive schemes (higher ratio off-injection period per cycle to the on-injection period per cycle and longer off-injection duration) with higher injection rates. Furthermore, a sensitivity analysis for offshore oil field characteristics (distance separating injectors and host platform, reservoir heterogeneity, reservoir symmetry, vertical transmissibility, rock wettability, reservoir pressure, capillary pressure, and intermittent injection initiation time) is conducted. Wind-powered intermittent and cyclic injection schemes are economically feasible mainly in heterogeneous layered reservoirs. Offshore sites with superb wind power provides the highest internal rate of return (IRR) for the fully-wind powered scenario. Offshore Locations with relatively lower wind resource (down to good level of wind power potential) and favourable wind variability patterns can still achieve a higher net present value (NPV), yet at a lower IRR. As larger and more costly wind power systems is required to enhance the oil recovery. The economic and environmental benefits of wind-powered injection schemes is attributed to a higher energy efficiency (in terms of the number of crude oil barrels recovered per MWh), as well as a significant reduction in greenhouse gas emissions, fuel costs, and power transmission costs. Both fully and partially wind-powered schemes are considered more economically favourable under higher oil price environment, lower weighted average cost of capital, longer distances separating host platform and injection wells, higher carbon tax and more stringent environmental conditions.