Gas Capillary Inhibition to Oil Production

Erendi, Alex; Cathles, L. M.

doi:10.5724/gcs.01.21.0607

Cited by 3 publications

(3 citation statements)

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“…The damage will be fastest and greatest for the best producing wells because the drawdown cone for such wells extends further and encounters more capillary barriers. If production is stopped, the pressure will recover, the exsolved gas will dissolve, and the well will produce as it did initially [65]. Shosa seals have production implications.…”

Section: Impact On Oil Productionmentioning

confidence: 99%

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On the Processes that Produce Hydrocarbon and Mineral Resources in Sedimentary Basins

Cathles

2019

Geosciences

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Sedimentary basins are near-planetary scale stratigraphic-structural-thermochemical reactors that produce a cornucopia of organic and inorganic resources. The scale over which fluid movements coordinate in basins and the broad mix of processes involved is remarkable. Easily observed characteristics indicate the style of flow that has operated and suggest what kind of resources the basin has likely produced. The case for this proposition is built by reviewing and interpreting observations. Features that future basin models might include to become more effective exploration and development tools are suggested.

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Section: Impact On Oil Productionmentioning

confidence: 99%

“…If production is stopped, the pressure will recover, the exsolved gas will dissolve, and the well will produce as it did initially. [65]. Shosa seals have production implications.…”

Section: Impact On Oil Productionmentioning

confidence: 99%

On the Processes that Produce Hydrocarbon and Mineral Resources in Sedimentary Basins

Cathles

2019

Geosciences

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“…Full details of the experiment are given in Shosa & Cathles (2001). Related papers in the same publication describe the broad implications of capillary seals in basins (Cathles 2001), their implications for porosity‐depth profiles in basins (Revil & Cathles 2001), and their potential impact on oil production under conditions of gas exsolution (Erendi & Cathles 2001).…”

Section: The Operation Of Gas Pulsarsmentioning

confidence: 99%

Changes in sub‐water table fluid flow at the end of the Proterozoic and its implications for gas pulsars and MVT lead–zinc deposits

Cathles¹

2007

Geofluids

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A fundamental change in the nature of sub-water table fluid flow occurred at roughly the Proterozoic-Phanerozoic boundary when organic matter began to be buried in sufficient quantities that nonaqueous fluids could occupy a significant fraction of the pore space. This allowed the formation of remarkably durable capillary seals that could trap gas in large portions (hundreds of kilometers) of a basin for hundreds of millions of years. Gas loss from these gas zones can be highly dynamic, especially during gas generation. Under the right circumstances, hundreds of cubic kilometers of gas can be rapidly discharged into adjacent permeable aquifers. In Pennsylvanian/Permian time, the Arkoma Basin may have repeatedly discharged such volumes of gas into the very permeable Cambrian sandstone and karstic carbonate aquifers of the mid-continent of the United States. This could have displaced brines rapidly enough to form the Mississippi Valley-type (MVT) lead-zinc deposits of this age that are associated with the Arkoma Basin, heating them only briefly as required by maturity indicators. Sea level rise accompanying the melting of Permian continental glaciers may have triggered the gas expulsion events. This radically new mechanism for the formation of MVT deposits is just one example of the nonlinear dynamics of gas accumulations that are possible since Late Proterozoic time.

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The physics of gas chimney and pockmark formation, with implications for assessment of seafloor hazards and gas sequestration

Cathles

Zheng

Chen

2010

Marine and Petroleum Geology

224

171

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a b s t r a c tPockmarks form where fluids discharge through seafloor sediments rapidly enough to make them quick, and are common where gas is present in near-seafloor sediments. This paper investigates how gas might lead to pockmark formation. The process is envisioned as follows: a capillary seal traps gas beneath a fine-grained sediment layer or layers, perhaps layers whose pores have been reduced in size by hydrate crystallization. Gas accumulates until its pressure is sufficient for gas to invade the seal. The seal then fails completely (a unique aspect of capillary seals), releasing a large fraction of the accumulated gas into an upward-propagating gas chimney, which displaces water like a piston as it rises. Near the seafloor the water flow causes the sediments to become ''quick'' (i.e., liquefied) in the sense that grain-to-grain contact is lost and the grains are suspended dynamically by the upward flow. The quickened sediment is removed by ocean-bottom currents, and a pockmark is formed. Equations that approximately describe this gas-piston-water-drive show that deformation of the sediments above the chimney and water flow fast enough to quicken the sediments begins when the gas chimney reaches half way from the base of its source gas pocket to the seafloor. For uniform near-surface sediment permeability, this is a buoyancy control, not a permeability control. The rate the gas chimney grows depends on sediment permeability and the ratio of the depth below seafloor of the top of the gas pocket to the thickness of the gas pocket at the time of seal failure. Plausible estimates of these parameters suggest gas chimneys at Blake Ridge could reach the seafloor in less than a decade or more than a century, depending mainly on the permeability of the deforming near-surface sediments. Since these become quick before gas is expelled, gas venting will not provide a useful warning of the seafloor instabilities that are related to pockmark formation. However, detecting gas chimney growth might be a useful risk predictor. Any area underlain by a gas chimney that extends half way or more to the surface should be avoided.

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Gas Capillary Inhibition to Oil Production

Cited by 3 publications

References 0 publications

On the Processes that Produce Hydrocarbon and Mineral Resources in Sedimentary Basins

On the Processes that Produce Hydrocarbon and Mineral Resources in Sedimentary Basins

Changes in sub‐water table fluid flow at the end of the Proterozoic and its implications for gas pulsars and MVT lead–zinc deposits

The physics of gas chimney and pockmark formation, with implications for assessment of seafloor hazards and gas sequestration

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