Quantification of the magnitude of net erosion in the southwest Barents Sea using sonic velocities and compaction trends in shales and sandstones

Ktenas, Dimitrios; Henriksen, E.; Meisingset, I.; Nielsen, Jens Kvist; Andreassen, Karin

doi:10.1016/j.marpetgeo.2017.09.019

Cited by 31 publications

(42 citation statements)

References 61 publications

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“…Assuming the values proposed by Sclater and Christie (1980), yields a mean value of net erosion of ≈3500 m with a standard deviation of 100 m (Table 3). This is significantly higher than values inferred by compaction studies in this area for the Cenozoic erosional event (1800-2400 m) (Ktenas, Henriksen, Meisingset, Nielsen, & Andreassen, 2017;Ktenas, Meisingset, Henriksen, & Nielsen, 2018). The compaction parameters estimated for the North Sea by Sclater and Christie (1980) are often the default values in basin modelling and for net erosion estimation (Iliffe, Lerche, & DeBuyl, 1992;Nyland, Jensen, Skagen, Skarpnes, & Vorren, 1992;Corcoran & Doré, 2005;Zieba, Daszinnies, Emmel, Lothe, Grover, & Lippard, 2014).…”

Section: Discussionmentioning

confidence: 77%

Estimating uncertainties on net erosion from well‐log porosity data

2019

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Estimating the amount of erosion experienced by a sedimentary basin during its geological history plays a key role in basin modelling. In this paper, we present a novel probabilistic approach to estimate net erosion from porosity-depth data from a single well. Our approach uses a Markov chain Monte Carlo algorithm which readily allows us to deal with imprecise knowledge of the lithology-dependent compaction parameters in a joint inversion scheme using multiple lithologies. The results using synthetic data highlight the advantages of our approach over conventional techniques for net erosion estimation: (a) uncertainties on compaction parameters can be effectively mapped into a probabilistic solution for net erosion; (b) posterior uncertainties are easy to quantify; (c) the joint inversion scheme can automatically reconcile porosity data from different lithologies. Our results also underscore the critical role of prior assumptions on controlling the retrieved estimates for net erosion. Using real data from a well in the Barents Sea, we simulate three possible scenarios of variable prior assumptions on compaction parameters to demonstrate the general applicability of our approach. Strong prior assumptions on the compaction parameters led to unrealistic estimates of net erosion for the target well, indicating the assumptions are probably inappropriate. Our preferred strategy for this dataset is to include additional data to constrain the normal compaction trend of the sediments. This provides a net erosion estimate for the target well of about 2300 m with a standard deviation of 140 m which is in line with previous studies. Finally, we discuss potential guidelines to deal with real applications in which data from normally compacted sediments are not available. One is to use our algorithm as a hypothesis-testing tool to evaluate the results under a large set of assumed compaction parameters. A second is to infer compaction parameters and net erosion simultaneously from the target well porosity data. Although appealing and successful with synthetic data, this strategy provides results which are strongly dependent on the calibration data and the geological history of the sediments sampled by the target well. Highlights• A probabilistic approach to estimate net erosion from well-log compaction data is presented. • Uncertainties in the compaction model are effectively propagated in the solution for net erosion. • The novel methodology is tested against synthetic data and real data from a well in the Barents Sea.

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Section: Discussionmentioning

confidence: 77%

Estimating uncertainties on net erosion from well‐log porosity data

2019

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“…In the Hammerfest Basin, maximum burial is estimated to have been of the order of 900 m deeper than present (Henriksen et al 2011;Ktenas et al 2017). A large part of this erosion can be assumed to be glacial (Elverhøi et al 1998).…”

Section: Abnormally Pressured Formaɵonsmentioning

confidence: 99%

Use of pore pressure data from the Norwegian Continental Shelf to characterize fluid-flow processes in geological timescales

Riis¹,

Wolff²

2020

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A dataset with pore pressures from more than 1000 exploration wells has been used to investigate the dynamics of aquifer systems in the Norwegian Continental Shelf (NCS). Variations in aquifer pressures reflect flow of porewater through permeable rocks over geological time. Strongly overpressured regimes are formed within confined aquifers in subsiding areas, where fluid flow out of the aquifer is controlled by vertical seepage. In transitional pressure regimes, fluid flows within permeable beds towards areas with hydrostatic pressures. In the hydrostatic regime, pressure differences result from density differences due to varying formation water salinity and by hydrocarbon columns. An underpressured regime has been encountered in confined aquifers in the platform areas of the Barents Sea, and is related to net uplift and erosion. In the case studies, pressure differences are interpreted in the context of the relevant pressure regime, and with a dynamic approach where segment boundaries and cap rocks are regarded as low-permeability restrictions rather than barriers. The present distribution of pressure regimes was developed over the last few million years due to rapid Pleistocene sedimentation and erosion processes.

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“…Since the area of interest is located at the western edge of the Barents Sea, there is only limited to moderate uplift (0 to 1000 m, Table 1) according to previous studies (e.g. Riis & Fjeldskaar 1992;Ohm et al 2008;Henriksen et al 2011;Baig et al 2016;Ktenas et al 2017). However, the disparity between the uplift values between different studies is noticeable, owing possibly to the various methods employed.…”

Section: Geological Settingmentioning

confidence: 90%

“…However, the disparity between the uplift values between different studies is noticeable, owing possibly to the various methods employed. Ohm et al (2008) and Henriksen et al (2011) suggested no exhumation in the areas of the Senja Ridge and the western margin of Tromsø Basin, whereas, Riis & Fjeldskaar (1992), Baig et al (2016) and Ktenas et al (2017) suggested moderate exhumation (250-1000 m) in these areas ( Fig. 3).…”

Section: Geological Settingmentioning

confidence: 97%

Diagenetic related flat spots within the Paleogene Sotbakken Group in the vicinity of the Senja Ridge, Barents Sea

Fawad

Mondol

Baig

et al. 2019

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Rock physics analyses of data from a wildcat well 7117/9-1 drilled in the Senja Ridge area, located in the Norwegian Barents Sea, reveal a change in stiffness within the fine-grained Paleogene Sotbakken Group sediments, caused by the transformation of opal-A to opal-CT, and opal-CT to quartz. This change manifests as flat spots on 2D seismic profiles. These flat spots were mistaken as hydrocarbon-water contacts, which led to the drilling of well 7117/9-1. Rock physics analyses on this well combined with a second well (7117/9-2) drilled further northwest and updip on the Senja Ridge, indicate overpressure within the opal-CT rich zones overlying the opal-CT to quartz transformation zones in the two wells. The absence of opal-A to opal-CT and opal-CT to quartz flat spots on seismic in the second well is attributed to differences in temperature and timing of uplift. In AVA modelling, both the opal-A to opal-CT and opal-CT to quartz interface points plotted on the wet trend, whereas the modelled gas-brine, oil-brine and gas-oil contacts fell within the quadrant-I. These findings will be useful in understanding the nature of compaction of biogenic silica-rich sediments where flat spots could be misinterpreted as hydrocarbon related contacts in oil and gas exploration.

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Quantification of the magnitude of net erosion in the southwest Barents Sea using sonic velocities and compaction trends in shales and sandstones

Cited by 31 publications

References 61 publications

Estimating uncertainties on net erosion from well‐log porosity data

Estimating uncertainties on net erosion from well‐log porosity data

Use of pore pressure data from the Norwegian Continental Shelf to characterize fluid-flow processes in geological timescales

Diagenetic related flat spots within the Paleogene Sotbakken Group in the vicinity of the Senja Ridge, Barents Sea

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