Qiu, Z., Zhang, Y., Zhao, X., He, Q., Chen, Z., Zhao, C., 2019. An experimental study on the optimization of drilling fluid in offshore gas hydrate formations. Natural Gas Industry 39, 104-109.

http://oversea.cnki.net/kcms/detail/detail.aspx?dbCode=cjfd&QueryID=20&CurRec=18&filename=TRQG2019 12018&dbname=CJFDAUTO In Chinese. In the process of drilling offshore gas hydrate( "hydrate" for short) formations, the invasion of drilling fluid into formations may lead to hydrate decomposition, which will result in borehole instability. In order to solve these difficulties, this paper experimentally studied the decomposition law of methane hydrate under different decomposition modes. Then, the Peng - Robinson equation was introduced to calculate the change of methane gas mole number, and the experimental method for evaluating the inhibition of hydrate decomposition by drilling fluid was optimized. Finally, the effects of the kinetic inhibitor DY-1 and modified lecithin on the decomposition characteristics of hydrate were experimentally analyzed using this method, and the water-based drilling fluid suitable for gas hydrate formations was further optimized. And the following research results were obtained. First, the best way to evaluate the inhibition of drilling fluid on hydrate decomposition is to inject cold solution without relieving the pressure. Second, the DY-1 and modified lecithin can retard hydrate decomposition by adsorbing in hydrate surface to inhibit heat and mass transfer, so they can be used as hydrate decomposition inhibitors of drilling fluid. Third, the optimized drilling fluid system has good low-temperature rheological properties and shale inhibition and lubricity and can inhibit the formation and the decomposition of hydrates, so it can meet the basic requirements of drilling fluid technology for offshore gas hydrate formations. It is concluded that the research results can provide a drilling fluid technical support for the development of hydrates in China.

Quarles, B., Barnes, J.W., Lissauer, J.J., Chambers, J., 2019. Obliquity evolution of the potentially habitable exoplanet Kepler-62f. Astrobiology 20, 73-90.

https://doi.org/10.1089/ast.2018.1932 Variations in the axial tilt, or obliquity, of terrestrial planets can affect their climates and therefore their habitability. Kepler-62f is a 1.4 R planet orbiting within the habitable zone of its K2 dwarf host star. We ⊕ perform N-body simulations that monitor the evolution of obliquity of Kepler-62f for 10-million-year timescales to explore the effects on model assumptions, such as the masses of the Kepler-62 planets and the possibility of outer bodies. Significant obliquity variation occurs when the rotational precession frequency ≲ overlaps with one or more of the secular orbital frequencies, but most variations are limited to 10°. Moderate ∼ variations ( 10 - 20°) can occur over a broader range of initial obliquities when the relative nodal longitude (ΔΩ) overlaps with the frequency and phase of a given secular mode. However, we find that adding outer gas ∼ ∼ giants on long-period orbits ( 1000 days) can produce large ( 60°) variations in obliquity if Kepler-62f has a very rapid (4 h) rotation period. The possibi lity of giant planets on long-period orbits impacts the climate and habitability of Kepler-62f through variations in the latitudinal surface flux, where large variations can occur on million year timescales.

Quivelli, O., Marino, M., Rodrigues, T., Girone, A., Maiorano, P., Abrantes, F., Salgueiro, E., Bassinot, F., 2020. Surface and deep water variability in the Western Mediterranean (ODP Site 975) during insolation cycle 74: High-resolution calcareous plankton and molecular biomarker signals. Palaeogeography, Palaeoclimatology, Palaeoecology 542, 109583.

http://www.sciencedirect.com/science/article/pii/S003101821930745X We reconstructed changes in productivity and surface/subsurface and deep-water dynamics in the Western Mediterranean through a multi-proxy study of Ocean Drilling Program Site 975 between late Marine Isotope Stage (MIS) 20 and early interglacial MIS 19. Our high-resolution study (down to ~200-year resolution) combines calcareous plankton assemblages (coccolithophores and foraminifera), biomarkers (C -alkenones, n- 37 alkanes, n-alcohols) and elemental proxies (total organic carbon, total nitrogen, calcium carbonate). Surface