| Preview |
Abstract
The continued increase in oil demand associated with the growing concern about
the greenhouse gases has been an additional driver for CO2 injection into oil
reservoirs. The application of this EOR method usually occurs at a later stage
in the development of a field in which the operating surface facilities were
normally not specified to manage high levels of CO2. Therefore, the aim of this
work is to evaluate, by proper fluid characterization and compositional
reservoir simulation, the benefits and risks of CO2 injection in a particular
sector of an offshore reservoir, surrounded by production units not fully
specified to deal with elevated concentrations of CO2.
The presented workflow, combining reservoir engineering analysis with
production equipment aspects, can be applied to any target field for a CO2
injection project. However, it is even more relevant for mature offshore
fields, where a CO2 production growth leading to the necessity of replacing all
production facilities would probably make the project fail economically.
For the particular field analyzed in this article, the deployment of a
production unit able to inject CO2 from an external source in an undrained
region of the reservoir, hydraulically connected to an area already in
production, would bring benefits not only to the region where the injection
would occur but also to the adjacent area. The CO2 migration to the neighboring
area decreases the levels of CO2 to be processed in the new platform plant,
allowing its technical and economic feasibility, as well as increases the
recovery factor of the adjoining area, without reaching levels of CO2 and gas
flow rates beyond the limits of the plant already in operation. Furthermore,
the reservoir’s capacity to retain CO2, acting as a carbon sink, is also
evaluated.
This study thus presents an integrated workflow for an optimal CO2 injection
project design, considering not only the benefits in terms of recovery in the
target area of the project, but analyzing the impacts and risks to surrounding
areas.
Introduction
The continued increase in oil demand associated with the growing concern about
the greenhouse gases has been an additional driver for CO2 injection into oil
reservoirs. Carbon capture and storage (CCS), in saline aquifers for example,
has been increasingly studied and has started to be applied due to higher
environmental concern. However, the investment necessary for this process is
quite high, without a significant financial return for the industry. On the
other hand, the use of CO2 as an EOR strategy, which also acts as a carbon
storage method thanks to the fact that great part of the injected CO2 is
retained in the reservoir, can bring a very significant revenue gain by
increasing the recovery in oil fields, especially in mature reservoirs. Thus,
as CO2 EOR can put together the goals of profitability and environmental
responsibility, it is likely to become a successful path to be followed in the
near future in offshore oil industry as it is already onshore.
Nevertheless, the application of this EOR method usually occurs at a later
stage in the development of a field in which the operating facilities were
normally not specified to manage high levels of CO2. This means reservoir
engineering analysis has to be done closely associated with production
equipment aspects and constraints, so that a high CO2 production growth leading
to the necessity of replacing production facilities is avoided. Otherwise, the
project would probably fail from the economic point of view. This study thus
presents an integrated workflow for an optimal CO2 injection project design,
considering not only the benefits in terms of oil recovery and CO2 storage, but
analyzing the impacts and risks of implementing this kind of method.
|
