Taenzer, L., Carini, P.C., Masterson, A.M., Bourque, B., Gaube, J.H., Leavitt, W.D., 2020. Microbial methane from methylphosphonate isotopically records source. Geophysical Research Letters 47, e2019GL085872.

https://doi.org/10.1029/2019GL085872 Abstract: Methane is a potent greenhouse gas commonly supersaturated in the oxic surfaces waters of oceans and lakes, yet canonical microbial methanogens are obligate anaerobes. One proposed methane production pathway involves microbial degradation of methylphosphonate (MPn), which can proceed in the presence of oxygen. Directly tracing dissolved methane to its source in oxic waters, however, remains a challenge. To address this knowledge gap, we quantified the carbon isotopic fractionation between substrate MPn and product methane (1.3‰) in lab experiments, which was 1 to 2 orders of magnitude smaller than canonical pathways of microbial methanogenesis (20 to 100‰). Together, these results indicated that microbial catabolism of MPn is a source of methane in surface oceans and lake waters, but to differentiate sources of MPn in nature a further accounting of all sources is necessary. Methane from this pathway must be considered in constraining the marine carbon cycle and methane budget. Plain Language Summary: Each year microbes in the surface of lakes and oceans capture gigatons of carbon dioxide from the atmosphere. Some of this organic carbon is converted to the potent greenhouse gas methane right there in the surface waters, where it may easily escape to the atmosphere. Precisely how much methane is released from one specific microbial pathway that is intimately involved in the cycling of both carbon and phosphorus remains an outstanding question. To enable environmental geoscientists to track this process, we establish isotopic 'fingerprint' of this process in the laboratory. Using these lab-derived constraints, we reinterpreted the limited available C-isotopic data from methane dissolved in oxygenated ocean and lake waters.

Takeya, M., Ubaidah, A., Shimokawara, M., Okano, H., Nawa, T., Elakneswaran, Y., 2020. Crude oil/brine/rock interface in low salinity waterflooding: Experiments, triple-layer surface complexation model, and DLVO theory. Journal of Petroleum Science and Engineering 188, 106913.

http://www.sciencedirect.com/science/article/pii/S0920410520300127 The determination of the electrokinetic properties of crude oil/brine and rock/brine interfaces is necessary to understand and evaluate the low salinity waterflooding (LSWF) effect on wettability alteration and enhanced oil recovery (EOR). The interface properties and characteristics of oil and rock minerals significantly affect LSWF and must be elucidated in detail. Herein, the interaction of crude oil, brine, and rock was studied to elucidate the LSWF effect in carbonate and sandstone reservoirs. A triple-layer surface complexation model was proposed to describe the calcite/brine and kaolinite/brine interfaces and was verified with zeta potential experiments at various pH and calcium, magnesium, and sulphate concentrations. Furthermore, the surface complexation model prediction of zeta potential agreed well with the measured data for the suspension in seawater, formation water, and associated dilutions. The predicted surface potential of crude oil, calcite, and kaolinite was used in Derjaguin-Landau-Verwey-Overbeek (DLVO) theory to estimate the total disjoining pressure as attractive/repulsive forces. The interaction between crude oil and calcite/kaolinite on seawater dilution and in the presence of sulphate in the diluted solution for calcite was evaluated via disjoining pressure. Moreover, the importance of electrokinetic properties on attractive/repulsive forces and the mechanisms for wettability alteration in crude oil-brine-kaolinite due to LSWF as well as in oil-brine-calcite because of sulphate addition are discussed.

Taleb, F., Lemaire, M., Garziglia, S., Marsset, T., Sultan, N., 2020. Seafloor depressions on the Nigerian margin: Seabed morphology and sub-seabed hydrate distribution. Marine and Petroleum Geology 114, 104175.

http://www.sciencedirect.com/science/article/pii/S0264817219306294 Gas hydrate quantification using acoustic data requires proper knowledge of the mineralogy of their host sediment. In this paper, a petrophysical model allowing GH quantification at sites where mineralogy profiles are absent is proposed. This approach is applied to a high gas flux pockmark system in the Gulf of Guinea where in-situ acoustic and geotechnical measurements together with core measurements could have been correlated