Resolving a Permeabilty Mismatch in a Mature Carbonate Field

Oates, Michael; Mishra, Gaurav; Sultana, N.; Nath, Gitashree

doi:10.2118/155458-ms

Cited by 1 publication

(3 citation statements)

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“…Numerous studies, supported by a steady water-cut profile over the field's long production history (Fig. 3), indicate that a connected natural fracture network is probably absent in Field X (Oates et al 2012).…”

Section: Permeability Modelling Challenges In Field Xmentioning

confidence: 94%

“…4), which are continuous across the field. The reservoir contains an oil rim about 20 m thick below a gas column of up to 50 m. The oil rim is being produced through a gas cap drive mechanism (Oates et al 2012). The main reservoir zones are interpreted to be highstand systems tracts and their stratigraphic framework is summarized as a stacked depositional sequence in a distally steepened shallow ramp setting (Fig.…”

Section: Permeability Modelling Challenges In Field Xmentioning

confidence: 99%

“…Hence, an accurate re-evaluation of the horizontal permeability, K h , for the CEP zones is needed. Considering the drive mechanism in Field X where the oil rim is produced by expanding the gas cap (Oates et al 2012), it is expected that the ratio of vertical to horizontal permeability, K v /K h , needs to be modelled accurately in Field X to capture the main flow mechanisms. It is therefore crucial to disentangle and understand how the different solution-enhanced porosity types in the CEP zones, from microporosity to leached stylolites and tension-gashes, impact reservoir permeability individually and cumulatively.…”

Section: Near-wellbore Modelling and Upscaling Workflowmentioning

confidence: 99%

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Evaluating the impact of a late-burial corrosion model on reservoir permeability and performance in a mature carbonate field using near-wellbore upscaling

Chandra

Wright

Barnett

et al. 2014

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Field X comprises a giant Palaeogene limestone reservoir with a long production history. An original geomodel used for history matching employed a permeability transform derived directly from core data. However, the resulting permeability model required major modifications, such as horizontal and vertical permeability multipliers, in order to match the historic data. The rationale behind these multipliers is not well understood and not based on geological constraints. Our study employs an integrated near-wellbore upscaling workflow to identify and evaluate the geological heterogeneities that enhanced reservoir permeability. Key among these heterogeneities are mechanically weak zones of solution-enhanced porosity, leached stylolites and associated tension-gashes, which were developed during late-stage diagenetic corrosion. The results of this investigation confirmed the key role of diagenetic corrosion in enhancing the permeability of the reservoir. Insights gained from the available production history, in conjunction with petrophysical data analysis, substantiated the characterization of this solution-enhanced permeability. This study provided valuable insights into the means by which a satisfactory field-level history match for a giant carbonate reservoir can be achieved. Instead of applying artificial permeability multipliers that do not necessarily capture the impacts of geological heterogeneities, our method incorporates representations of fine-scale heterogeneities. Improving the characterization of permeability distribution in the field provided an updated and geologically consistent permeability model that could contribute to the ongoing development plans to maximize incremental oil recovery. Field X is a giant offshore oil and gas field with a long production history from a limestone reservoir. Permeability has been identified as one of the biggest uncertainties associated with the reservoir simulation model during field optimization studies that have been carried out by the operator previously. A reduction in the uncertainties for the permeability distribution is needed to evaluate the feasibility of the next development phase.In this study we attempt to resolve these issues through a systematic re-evaluation of the reservoir simulation model, considering, in particular, the field's diagenetic history. Our aim is to understand the fundamental controls on fluid flow that need to be adequately captured in the reservoir model. Geological studies carried out by the operator suggest that the key permeability pathways are strongly related to the mechanism of reservoir porosity -permeability evolution during late-burial corrosion (Wright & Barnett 2011). Late-burial corrosion in Field X is referred to as deep burial/ mesogenetic corrosion associated with the corrosion of limestone by burial-derived (hypogene) fluids. However, it is unclear how a diagenetic model that accounts for late-burial corrosion should be included in the reservoir simulation model and how such an updated reservoir simulation model could i...

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Section: Permeability Modelling Challenges In Field Xmentioning

confidence: 94%

Section: Permeability Modelling Challenges In Field Xmentioning

confidence: 99%

Section: Near-wellbore Modelling and Upscaling Workflowmentioning

confidence: 99%

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