Fluid Migration through Permafrost and the Pool of Greenhouse Gases in Frozen Soils of an Oil and Gas Field

Abstract

Most methane (CH4) and carbon dioxide (CO2) emissions originate from the biodegradation of organic matter of soils and of degrading permafrost in the Arctic. However, there is limited evidence of the activity of geological sources, and little understanding of the pathways of migration of gaseous fluids through the porous mineral matrix filled with ice. We estimated the effect of geological factors on the winter storage of the greenhouse gases in frozen soils by statistical analysis of the geodatabase, which combined a field gas survey of frozen soils, subsurface sounding, and remote sensing data. Frozen soils stored on average 0.016 g CH4 m−3 and 11.5 g CO2 m−3. Microseeps, recognized by isolated anomalies of helium, had 30% higher CH4 concentrations. Lineaments marking margins of tectonic blocks were estimated to have 300% higher CH4 concentrations. High concentrations of propane and ethane indicated the contribution of diffuse fluid flow from hydrocarbon-bearing beds on 95% of the 130 km2 study area. In addition to the fluid contribution, we estimated an overwintering pool of greenhouse gases in frozen soil for the first time. Being at least 0.01–0.1% of the soil organic matter mass, these gaseous forms of carbon can be critical for the early-summer Arctic ecosystem functioning.

Thermal Conductivity of Frozen and Unfrozen Gas-Saturated Soils

“…Intensive exploration of the Russian Arctic regions for petroleum production has revealed large amounts of gas, especially methane, stored in permafrost [1][2][3][4][5][6][7][8][9][10][11][12]. Gas accumulations are found at different depths within permafrost but are especially abundant at shallow levels above the Gas Hydrate Stability Zone (GHSZ) [13][14][15][16][17][18][19][20][21].…”

Experimental Investigation on Fracture Behavior and Mechanical Properties of Red Sandstone Subjected to Freeze-thaw Cycles

“…Permafrost accounts for almost half of the land in the world [1,2] and a lot of mineral resources such as coal [3][4][5] , oil [6,7] and gas [8][9][10] stored in the cold region. In this area, temporal cyclic variations in temperature result in freeze-thaw cycles, exposing the rock undergo micro-damage, and further leading to the failure of rock matrix and instability of rock engineering.…”

Experimental Investigation on Fracture Behavior and Mechanical Properties of Red Sandstone Subjected to Freeze–Thaw Cycles

“…Permafrost accounts for almost half of the land in the world [1,2] and a great deal of the mineral resources, such as coal [3][4][5], oil [6,7], and gas [8][9][10], stored in cold regions. In this area, temporal cyclic variations in temperature result in freeze-thaw cycles, exposing the rock and causing micro-damage, and further leading to the failure of the rock matrix and the instability of rock engineering.…”