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| Titel |
Experimental Investigations into CO2 Interactions with Injection Well Infrastructure for CO2 Storage |
| VerfasserIn |
Amer Syed, Ji-Quan Shi, Sevket Durucan, Graham Nash, Anna Korre |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250081185
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| Zusammenfassung |
| Wellbore integrity is an essential requirement to ensure the success of a CO2 Storage project
as leakage of CO2 from the injection or any other abandoned well in the storage complex,
could not only severely impede the efficiency of CO2 injection and storage but also may
result in potential adverse impact on the surrounding environment. Early research has
revealed that in case of improper well completions and/or significant changes in operating
bottomhole pressure and temperature could lead to the creation of microannulus at
cement-casing interface which may constitute a preferential pathway for potential CO2
leakage during and post injection period. As a part of a European Commission funded
CO2CARE project, the current research investigates the sealing behaviour of such
microannulus at the cement-casing interface under simulated subsurface reservoir pressure
and temperature conditions and uses the findings to develop a methodology to assess the
overall integrity of CO2 storage.
A full scale wellbore experimental test set up was constructed for use under elevated pressure
and temperature conditions as encountered in typical CO2 storage sites. The wellbore cell
consists of an assembly of concentric elements of full scale casing (Diameter= 0.1524m),
cement sheath and an outer casing. The stainless steel outer ring is intended to simulate the
stiffness offered by the reservoir rock to the displacement applied at the wellbore.
The Central Loading Mechanism (CLM) consists of four case hardened shoes that
can impart radial load onto the well casing. The radial movement of the shoes is
powered through the synchronised movement of four precision jacks controlled
hydraulically which could impart radial pressures up to 15 MPa. The cell body is a gas
tight enclosure that houses the wellbore and the central loading mechanism. The
setup is enclosed in a laboratory oven which acts both as temperature and safety
enclosure.
Prior to a test, cement mix is set between the casing and outer steel ring. A radial pressure is
maintained on the wellbore casing during cement setting, i.e., the casing is in a state of
tension, so that a microannulus can be created by subsequent contraction of CLM when the
radial pressure is relieved. The aperture (permeability) of the microannulus can be controlled
by varying the CLM pressure on the casing, which is maintained throughout a flow test.
During a test, pure CO2/brine saturated CO2 is flown through the microannulus over
a period of time to study its permeability behaviour under simulated downhole
conditions. Evolution in permeability is monitored and the effluent is collected and
analysed regularly. These experimental results will be used as an input to implement a
time-dependent microannulus permeability in the numerical model to assess the
impact of such behaviour on the storage performance of a CO2 storage reservoir. The
results of the first set of experiments, where the permeability behaviour of pure CO2
was monitored over a 3 months period, are presented and discussed in this paper. |
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