Secondary Migration in a 2D Visual Laboratory Model

Vassenden, F.; Sylta, Øyvind; Zwach, C.

doi:10.3997/2214-4609.201405814

Cited by 11 publications

(6 citation statements)

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“…Vassenden et al [81] showed that about 65% of the hydrocarbon column height would be lost during the initial episode of leakage before snap off occurs [82]. This implies that once the fault's capillary entry pressure is overcome following the deglaciation at 0.8-0.78 Ma, the hydrocarbon column height decreases to~1/3 of the original.…”

Section: Overpressure Generation and Hydrofracturing Of Sealsmentioning

confidence: 99%

Role of Faults in Hydrocarbon Leakage in the Hammerfest Basin, SW Barents Sea: Insights from Seismic Data and Numerical Modelling

2017

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Hydrocarbon prospectivity in the Greater Barents Sea remains enigmatic as gas discoveries have dominated over oil in the past three decades. Numerous hydrocarbon-related fluid flow anomalies in the area indicate leakage and redistribution of petroleum in the subsurface. Many questions remain unanswered regarding the geological driving factors for leakage from the reservoirs and the response of deep petroleum reservoirs to the Cenozoic exhumation and the Pliocene-Pleistocene glaciations. Based on 2D and 3D seismic data interpretation, we constructed a basin-scale regional 3D petroleum systems model for the Hammerfest Basin (1 km × 1 km grid spacing). A higher resolution model (200 m × 200 m grid spacing) for the Snøhvit and Albatross fields was then nested in the regional model to further our understanding of the subsurface development over geological time. We tested the sensitivity of the modeled petroleum leakage by including and varying fault properties as a function of burial and erosion, namely fault capillary entry pressures and permeability during glacial cycles. In this study, we find that the greatest mass lost from the Jurassic reservoirs occurs during ice unloading, which accounts for a 60-80% reduction of initial accumulated mass in the reservoirs. Subsequent leakage events show a stepwise decrease of 7-25% of the remaining mass from the reservoirs. The latest episode of hydrocarbon leakage occurred following the Last Glacial Maximum (LGM) when differential loading of Quaternary strata resulted in reservoir tilt and spill. The first modeled hydrocarbon leakage event coincides with a major fluid venting episode at the time of a major Upper Regional angular Unconformity (URU,~0.8 Ma), evidenced by an abundance of pockmarks at this stratigraphic interval. Our modelling results show that leakage along the faults bounding the reservoir is the dominant mechanism for hydrocarbon leakage and is in agreement with observed shallow gas leakage indicators of gas chimneys, pockmarks and fluid escape pipes. We propose a conceptual model where leaked thermogenic gases from the reservoir were also locked in gas hydrate deposits beneath the base of the glacier during glaciations of the Hammerfest Basin and decomposed rapidly during subsequent deglaciation, forming pockmarks and fluid escape pipes. This is the first study to our knowledge to integrate petroleum systems modelling with seismic mapping of hydrocarbon leakage indicators for a holistic numerical model of the subsurface geology, thus closing the gap between the seismic mapping of fluid flow events and the geological history of the area.

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Section: Overpressure Generation and Hydrofracturing Of Sealsmentioning

confidence: 99%

Role of Faults in Hydrocarbon Leakage in the Hammerfest Basin, SW Barents Sea: Insights from Seismic Data and Numerical Modelling

2017

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“…(Other relevant terminology can be found in an overview presented by Hildenbrand et al) In general, P c,breakthrough > P c,entry . The snap-off pressure is usually 0.2–0.5 of the breakthrough pressure. , Based on the assumption of a cylindrical geometry with a radius r , the capillary pressure is given by the Laplace law P c = P C O 2 − P w = 2 σ cos nobreak0em.25em⁡ θ r where σ is the CO 2 –brine IFT, and θ is the contact angle. For a given caprock, P c is then determined by the IFT and by wettability.…”

Section: Leakage Controlled By Capillary Pressure and Permeabilitymentioning

confidence: 99%

“…Long-term caprock sealing research at the reservoir scale is impossible in laboratory experiments. Leakage experiments of core samples, however, have shown that leakage stops at a certain level (20% to 50% of the breakthrough column height) at which the k eff of the caprock for the nonwetting phase becomes zero. , …”

Section: Leakage Controlled By Capillary Pressure and Permeabilitymentioning

confidence: 99%

“…The snapoff pressure is usually 0.2−0.5 of the breakthrough pressure. 60,61 Based on the assumption of a cylindrical geometry with a radius r, the capillary pressure is given by the Laplace law…”

Section: ■ Diffusive Lossmentioning

confidence: 99%

“…Leakage experiments of core samples, however, have shown that leakage stops at a certain level (20% to 50% of the breakthrough column height) at which the k ef f of the caprock for the nonwetting phase becomes zero. 112,113 Numerical modeling is an efficient way to estimate sealing capacity in a geological time scale. CO 2 migration may occur through the permeable pathways in caprock that is otherwise performing well as a seal.…”

Section: ■ Diffusive Lossmentioning

confidence: 99%

See 2 more Smart Citations

Comprehensive Review of Caprock-Sealing Mechanisms for Geologic Carbon Sequestration

Song

Zhang

2012

Environ. Sci. Technol.

261

124

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CO(2) capture and geologic sequestration is one of the most promising options for reducing atmospheric emissions of CO(2). Its viability and long-term safety, which depends on the caprock's sealing capacity and integrity, is crucial for implementing CO(2) geologic storage on a commercial scale. In terms of risk, CO(2) leakage mechanisms are classified as follows: diffusive loss of dissolved gas through the caprock, leakage through the pore spaces after breakthrough pressure has been exceeded, leakage through faults or fractures, and well leakage. An overview is presented in which the problems relating to CO(2) leakage are defined, dominant factors are considered, and the main results are given for these mechanisms, with the exception of well leakage. The overview includes the properties of the CO(2)-water/brine system, and the hydromechanics, geophysics, and geochemistry of the caprock-fluid system. In regard to leakage processes, leakage through faults or fracture networks can be rapid and catastrophic, whereas diffusive loss is usually low. The review identifies major research gaps and areas in need of additional study in regard to the mechanisms for geologic carbon sequestration and the effects of complicated processes on sealing capacity of caprock under reservoir conditions.

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Physical Controls on the Creation and Persistence of Natural Marine-Seepage Slicks

Meurer

MacDonald

Asl

et al. 2022

Preprint

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Physical processes involved in the ascent of naturally seeped oil from the seafloor and its persistence as a slick are considered. Simplified, physics-based models are developed, drawing in part from the extensive literature concerned with anthropogenic releases of oil at sea. The first model calculates the ascent of oil droplets or oil-coated gas bubbles as they ascend to the sea surface from the seep source. The second model calculates slick longevity as a function of the effect of wind-driven breaking waves. Both models have simplified inputs and algorithms making them suitable for Monte Carlo-type analysis. Using the oil ascent model, we find that slicks from shallower seeps are offset farther relative to their water depth than those from deeper sources. The slick longevity model reveals four growth modes for seepage slicks: persistent (low wind speeds), ephemeral (high wind speeds), reset (all slicks are cleared from an area by high wind speeds), and aging (slick growth after a reset). A year's worth of modeled winds from the Gulf of Mexico indicate average slick ages of ˜12 hours. Taking account of the expected oil release duration implied by slick recurrences yields average slick longevities for high recurrence seeps of ˜6.5 hours and ˜5 hours for low recurrence seeps. Seep flux estimates that include the length of individual slicks and the constraints of local currents and wind implicitly take into account the impact of wind-speed history. Those that assume a slick age should be re-evaluated in light of the current findings.

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Secondary Migration in a 2D Visual Laboratory Model

Cited by 11 publications

References 0 publications

Role of Faults in Hydrocarbon Leakage in the Hammerfest Basin, SW Barents Sea: Insights from Seismic Data and Numerical Modelling

Role of Faults in Hydrocarbon Leakage in the Hammerfest Basin, SW Barents Sea: Insights from Seismic Data and Numerical Modelling

Comprehensive Review of Caprock-Sealing Mechanisms for Geologic Carbon Sequestration

Physical Controls on the Creation and Persistence of Natural Marine-Seepage Slicks

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