Mineralisation-related flow heterogeneity within the Zubair Formation in the Rumaila Oilfield, southern Iraq
[Thesis]
Al-Ziayyir, Haitham
Hodgetts, David
University of Manchester
2018
Thesis (Ph.D.)
2018
Modelling subsurface deposits is extremely challenging with limited subsurface datasets such as cores, wireline logs and seismic data. However, integrated studies, which rely on extensive subsurface datasets can lead to improve the quality of spatial and temporal distributions of subsurface reservoirs. Nevertheless, a significant source of uncertainty within subsurface reservoirs is the controls upon hydrodynamic pressure distributions is not well understood. The depositional system is responsible for the style of heterogeneity, which is connected to chemical and physical diagenetic processes. These diagenetic controls may have very local or broad impact on reservoir properties related to pressure distribution. The uncertainty in pressure distribution can be reduced by providing a more detailed knowledge of mineralisation related to flow heterogeneity using Scanning Electron Microscopy (SEM), Energy Dispersive Spectrum (EDX) and X-ray Computed Tomography (X-ray CT). In this study, volume images of representative samples of the mineralised Zubair sandstones obtained using X-ray tomography are to be used as the basis for Computational Fluid Dynamical (CFD) modelling. Three phase segmentation will enable pore space, quartz matrix and in-situ pyrite mineralisation to be isolated from the volume images, enabling mineralised and unmineralised mesh based representations of the samples to be generated. Mineralogical characterisation on a small scale may open new paths for improving understanding of the impact of mineralisation upon fluid flow. As well as reducing uncertainty related to flow heterogeneity on a larger scale. The most obvious finding to emerge from mineralogical characterisation performed in this study is that dendritic pyrite mineralisation comprises potentially signficant control upon pressure distribution. As well as using nondestructive technique such as X-ray computed tomography would be valuable to improve the understanding about the influence of mineralisation upon the trapping and transfer mobile geofluids by applying further studies, which are based on finite volume based flow solver to the collected images.