Reservoir Compaction, Subsidence And Creeping Through 3D/4D Geomechanics Modeling For Potential Co2 Storage Site In Sarawak, Malaysia
The paper presents a holistic approach on studying risk associated with reservoir compaction and seabed subsidence related to CO2 geological storage through a comprehensive workflow for determining reservoir compaction and seabed subsidence in a CO2 storage feasibility studies campaign on carbonate reservoir near offshore Sarawak, Malaysia. It shows how a 4-D coupled reservoir geomechanical model can be used to evaluate reservoir compaction and subsidence with reservoir pressure depletion and then CO2 injection by outlines how the results and findings drive key decisions in the planning of the CCS strategy development, design of the pressure arrays and total injection volume. Conventionally for such analyses to investigate reservoir compaction, seabed subsidence and creeping, either an analytical method based on elastic deformation and lab data or a numerical method decoupled from the reservoir using relatively simple constitutive models are used. Such practices would lead to under prediction of the reservoir deformation to mislead further detailed engineering decision making. Hence a holistic approach is deem necessary to address the pitfall of using the rather traditional method. The pragmatic method presented in the study is proven comprehensive as it includes drilling analysis to constructing and calibrating single well by corroborating with stringent laboratory testing campaign and combined with structural model and reservoir model to create a field wide 3-D geomechanical model using advanced time lapsed geomechanics simulation to better characterize and enumerate the risk on the reservoir storage. Coupled finite element simulations with the reservoir model provided predictions of the reservoir rock with modified Cam-Clay method considering for pore collapse in the reservoir. The paper also further highlight the significance of comprehensive evaluation method in reservoir compaction, creeping and surface subsidence for CO2 sequestration program.
In this study, utilisation of the latest techniques in advanced 4-D coupled reservoir geomechanical modelling reduce the study time and costs significantly, making it affordable for in-time solutions suitable for decision making to the CO2 sequestration team. Hence, it is possible to replicate of the novel strategy involving in CO2 storage development, focusing on main risks assessment which will ultimately affecting well integrity, reservoir injection upper limit and capacity, long term fluid containment, and monitoring, measuring and verification (MMV) programme as mitigation to monitor for advanced signs of potential geohazard leakage from reservoir to the seabed.
AAPG Datapages/Search and Discovery Article #90324 © 2018 AAPG Asia Pacific Region GTW, Pore Pressure & Geomechanics: From Exploration to Abandonment, Perth, Australia, June 6-7, 2018