Petroleum reservoir porosity versus depth: Influence of geological age

Ehrenberg, S. N.; Nadeau, Paul; Steen, Øyvind

doi:10.1306/06120908163

Cited by 92 publications

(29 citation statements)

References 31 publications

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“…Typical porosity-depth trends for siliciclastic reservoirs, show porosities of 10-15% at depths of 4000-5000 mbsf (Ehrenberg et al 2009). However, the Skagerrak reservoir sandstones retain remarkably good porosity, up to 35%, and a low degree of compaction with respect to their presentday depths of burial.…”

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confidence: 99%

Enhanced porosity preservation by pore fluid overpressure and chlorite grain coatings in the Triassic Skagerrak, Central Graben, North Sea, UK

Stricker¹,

Jones²

2016

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Current understanding of porosity preservation in deeply buried sandstone reservoirs tends to be focused on how diagenetic grain coatings of clay minerals and microquartz can inhibit macroquartz cementation. However, the importance of overpressure developed during initial (shallow) burial in maintaining high primary porosity during subsequent burial has generally not been appreciated. Where pore fluid pressures are high, and the vertical effective stress is low, the shallow arrest of compaction can allow preservation of high porosity and permeability at depths normally considered uneconomic. The deeply buried fluvial sandstone reservoirs of the Triassic Skagerrak Formation in the Central Graben, North Sea, show anomalously high porosities at depths greater than 3500 metres below sea floor (mbsf). Pore pressures can exceed 80 MPa in the upper part of the Skagerrak Formation at depths of 4000-5000 mbsf, where temperatures are above 1408C. The Skagerrak reservoirs commonly have high primary porosities of up to 35%, little macroquartz cement and variable amounts of diagenetic chlorite grain coats. This research sheds light on the complex controls on reservoir quality in the fluvial sandstones of the Skagerrak Formation by identifying the role of shallow overpressure in arresting mechanical compaction and the importance of chlorite detrital grain coatings in inhibiting macroquartz cement overgrowth as temperature increases during progressive burial.Gold Open Access: This article is published under the terms of the CC-BY 3.0 license.

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Enhanced porosity preservation by pore fluid overpressure and chlorite grain coatings in the Triassic Skagerrak, Central Graben, North Sea, UK

Stricker¹,

Jones²

2016

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“…8l). The importance of grain coating chlorite in preserving porosity has been recognized in many studies (Bloch et al, 2002;Ehrenberg et al, 2009;Ajdukiewicz and Lander, 2010;Tobin et al, 2010;Taylor et al, 2010;Ozkan et al, 2011;Deschamps et al, 2012;Nguyen et al, 2013). For Chang 8 sandstone, where chlorite rims are present, the formation of quartz overgrowths is actually inhibited and thus porosity being preserved (Fig.…”

Section: Chloritementioning

confidence: 92%

Prediction of Diagenetic Facies using Well Logs: Evidences from Upper Triassic Yanchang Formation Chang 8 Sandstones in Jiyuan Region, Ordos Basin, China

Lai

Wang

Chai

et al. 2015

Oil Gas Sci. Technol. – Rev. IFP Energies nouvelles

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“…The estimation of decrease of K over age has been shown to exist [50], but quantification is not straightforward as the relation between porosity and age is influenced by many factors such as diagenesis, pressure, temperature, and erosion [51]. We chose to include a correction factor with age to exclude old (hard)rock, because an earlier study showed a more realistic distribution of aquifers throughout New Zealand by Tschritter et al (2016) [52].…”

Section: Appendix A4 Geologymentioning

confidence: 99%

Incorporation of Satellite Data and Uncertainty in a Nationwide Groundwater Recharge Model in New Zealand

2018

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A nationwide model of groundwater recharge for New Zealand (NGRM), as described in this paper, demonstrated the benefits of satellite data and global models to improve the spatial definition of recharge and the estimation of recharge uncertainty. NGRM was inspired by the global-scale WaterGAP model but with the key development of rainfall recharge calculation on scales relevant to national-and catchment-scale studies (i.e., a 1 km × 1 km cell size and a monthly timestep in the period 2000-2014) provided by satellite data (i.e., MODIS-derived evapotranspiration, AET and vegetation) in combination with national datasets of rainfall, elevation, soil and geology. The resulting nationwide model calculates groundwater recharge estimates, including their uncertainty, consistent across the country, which makes the model unique compared to all other New Zealand estimates targeted towards groundwater recharge. At the national scale, NGRM estimated an average recharge of 2500 m 3 /s, or 298 mm/year, with a model uncertainty of 17%. Those results were similar to the WaterGAP model, but the improved input data resulted in better spatial characteristics of recharge estimates. Multiple uncertainty analyses led to these main conclusions: the NGRM model could give valuable initial estimates in data-sparse areas, since it compared well to most ground-observed lysimeter data and local recharge models; and the nationwide input data of rainfall and geology caused the largest uncertainty in the model equation, which revealed that the satellite data could improve spatial characteristics without significantly increasing the uncertainty. Clearly the increasing volume and availability of large-scale satellite data is creating more opportunities for the application of national-scale models at the catchment, and smaller, scales. This should result in improved utility of these models including provision of initial estimates in data-sparse areas. Topics for future collaborative research associated with the NGRM model include: improvement of rainfall-runoff models, establishment of snowmelt and river recharge modules, further improvement of estimates of rainfall and AET, and satellite-derived AET in irrigated areas. Importantly, the quantification of uncertainty, which should be associated with all future models, should give further impetus to field measurements of rainfall recharge for the purpose of model calibration.

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Petroleum reservoir porosity versus depth: Influence of geological age

Cited by 92 publications

References 31 publications

Enhanced porosity preservation by pore fluid overpressure and chlorite grain coatings in the Triassic Skagerrak, Central Graben, North Sea, UK

Enhanced porosity preservation by pore fluid overpressure and chlorite grain coatings in the Triassic Skagerrak, Central Graben, North Sea, UK

Prediction of Diagenetic Facies using Well Logs: Evidences from Upper Triassic Yanchang Formation Chang 8 Sandstones in Jiyuan Region, Ordos Basin, China

Incorporation of Satellite Data and Uncertainty in a Nationwide Groundwater Recharge Model in New Zealand

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