Diagenetic evolution of the upper Cretaceous limestone and sandstone exhumed reservoirs in the western Basque–Cantabrian Basin,North Spain

The Basque–Cantabrian Basin (NE Spain) has been considered one of the most interesting areas for hydrocarbon exploration in the Iberian Peninsula since the 60th to 70th of last century. This basin is characterized by the presence of numerous outcrops of tar sands closely associated with fractures and Triassic diapirs. The aims of this work is to establish the diagenetic evolution of the Upper Cretaceous reservoir rocks with special emphasis in the emplacement of oil and their impact on reservoir quality. The studied rocks are constituted of carbonates and sandstones that contain massive quantities of bitumen filling vugs and fractures.Petrographic results indicate that the carbonate rocks from Maestu outcrops are bioclastic grainstones and wackestones, whereas the tar sandstones from Atauri and Loza outcrops are dominated by quartzarenites and subordinated subarkoses. The paragenetic sequence of the main diagenetic phases and processes include, pyrite, bladed and drusy calcite cement, calcite overgrowths, silicification of bioclasts and microcrystalline rhombic dolomite cement, and first stage of oil emplacement, blocky calcite cement, coarse crystalline calcite cement, calcitized dolomite, calcite veins, saddle dolomite and stylolites filled by the second phase of oil entrance. Together with the above mentioned diagenetic alterations, the arenites are affected by early kaolinitization of feldspars and the scarce formation of clay rim and epimatrix of illite. All sandstones and dolomitized carbonate rocks show high intercrystalline and intergranular porosity which is full by biodegraded hydrocarbons (solid bitumen). The biodegradation affects alkanes, isoprenoids and partially hopanes and steranes saturated hydrocarbons. Aromatics hydrocarbons, like naphthalenes, phenanthrenes, dibenzothiophenes and triaromatics are also affected by biodegradation. Results indicate that the first HC emplacement corresponds to early stage of calcite and dolomite cementation, and the second and more important emplacement is related to fracturation processes resulting in the formation of excellent reservoirs.     

基于傅里叶变换质谱的烃源岩成熟度评价方法及地质意义

<正>伴随非常规油气资源的勘探开发,油气资源开采的广度和深度进一步扩大,一定程度上缓解了我国油气供需矛盾、保障了我国能源安全,同时有力推动了能源结构战略转型。但同时也对能源地质研究工作提出了新的挑战。有机质成熟度是油气评价的重要参数之一,不同成熟阶段的有机质会对应产出不同成因、不同性质、不同质量的油气,如何准确评价沉积有机质成熟度是当前油气资源勘探开发工作的关键问题之一。前人在科研实践工作中从光学、化学、谱学等角度提出了适用条件各异的成熟度评价方法,在部分地质环境中获得了良好的应用效果,但已有的成熟度指标多受测定方法原理的制约导致其适用性不同程度受限(肖贤明等,2020),制约了油气资源的高质量勘探开发。     

Alteration of five organic compounds by glow discharge plasma and UV light under simulated Mars conditions

The Viking missions to Mars failed to detect any organic material in regolith samples. Since then, several removal mechanisms of organic material have been proposed. Two of these proposed methods are removal due to exposure to plasmas created in dust devils and exposure to UV irradiation. The experiments presented here were performed to identify similarities between the two potential removal mechanisms and to identify any compounds produced from these mechanisms that would have been difficult for the Viking instruments to detect. Five organic compounds, phenanthrene, octadecane, octadecanoic acid, decanophenone and benzoic acid, were exposed to a glow discharge plasma created in simulated martian atmospheres as might be present in dust devils, and to UV irradiation similar to that found at the surface of Mars. Glow discharge exposure was carried out in a chamber with 6.9 mbar pressure of a Mars like gas composed mostly of carbon dioxide. The plasma was characterized using emission spectroscopy and found to contain cations and excited neutral species including carbon dioxide, carbon monoxide, and nitrogen. UV irradiation experiments were performed in a Mars chamber which simulates the temperature, pressure, atmospheric composition, and UV fluence rates of equatorial Mars. The non-volatile residues left after each exposure were characterized by mass loss, infrared spectroscopy and high resolution mass spectrometry. Oxidized, higher molecular weight versions of the parent compounds containing carbonyl, hydroxyl and alkenyl functional groups were identified. The presence of these oxidized compounds suggests that searches for organic material in soils on Mars use instrumentation suitable for detection of compounds which contain the above functional groups. Discussions of possible reaction mechanisms are given.     

Titan trace gaseous composition from CIRS at the end of the Cassini-Huygens prime mission

This paper reports on the results from an extensive study of all nadir-looking spectra acquired by Cassini/CIRS during the 44 flybys performed in the course of the nominal mission (2004-2008). With respect to the previous study (Coustenis, A., and 24 colleagues [2007]. Icarus 189, 35-62, on flybys TB-T10) we present here a significantly richer dataset with, in particular, more data at high northern and southern latitudes so that the abundances inferred here at these regions are more reliable. Our enhanced high-resolution dataset allows us to infer more precisely the chemical composition of Titan all over the disk. We also include improved spectroscopic data for some molecules and updated temperature profiles. The latitudinal distributions of all of the gaseous species are inferred. We furthermore test vertical distributions essentially for acetylene (C₂H₂) from CIRS limb-inferred data and from current General Circulation Models for Titan and compare our results on all the gaseous abundances with predictions from 1-D photochemical-radiative models to check the reliability of the chemical reactions and pathways.     

The photochemical products of benzene in Titan’s upper atmosphere

The Cassini spacecraft detected benzene high in Titan’s atmosphere as well as the presence of large mass positive and negative ions. Previous work has suggested that these large mass ions could be composed of fused-ring polycyclic aromatic hydrocarbon compounds. These fused-ring PAHs, such as naphthalene and anthracene, are usually the result of high temperature processes that may not occur in Titan’s thin, cold, upper thermosphere. Here we suggest that a different class of aromatic compounds, polyphenyls, may be a better explanation of the data. Polyphenyls can grow to be large polymeric structures and could condense to form the aerosols seen in Titan’s cloud and hazes. They have similar properties to fused-ring PAHs (for example, electron affinity, ionization potential) and could be the negative ion species seen in the CAPS instrument data from the Cassini spacecraft.     

Urbanised beaches of the Ligurian coastal area (NW Mediterranean): A classification based on organic-matter characteristics and hydrolytic enzymatic activities

The beaches of Liguria have been intensively affected by human activities for over a century, transforming nearly the entire coastline from natural to urbanised and significantly upsetting beach ecological properties. The present study aims to investigate 9 Ligurian beaches characterised by different degree of urbanisation, to test if and to what extent the organic-matter (OM) recycling processes can be linked to the human activity. Swash zone sediment, sampled during the spring–summer–autumn period, when the anthropogenic influence is at its maximum due to tourism, was analysed for OM features and recycling processes. Multivariate statistical analyses showed that huge amounts of detrital OM accumulated in the more urbanised sites, where the anthropogenic influence was at its peak, deriving from higher inhabitant number and density, from the presence of crowded roads very near to the swash zone and sewage treatment plants. The presence of torrent outlets on the beaches provided further OM accumulation. Lipids, carbohydrates and degraded autotrophic pigments were the OM fractions mainly responsible of the differentiation, and rather constant, high labile phosphorus contents were found in the more urbanised sites. The high activity values of the hydrolytic enzymes indicate the response of the microbial system to the OM accumulation in the urban sites. However, a decoupling of the trends of some enzymatic activities (namely glucosidase and lipase) and their target OM was observed in the highly urbanised conditions.     

海洋污损细菌群落结构及其发酵液中化学成分的研究

从烟台附近海域通过挂板取样获得了污损微生物膜样品。利用高通量测序鉴定其中细菌有假交替单胞菌(Pseudoalteromonas sp.),芽孢杆菌(Bacillus sp.),盐单胞菌(Halomonas sp.),嗜冷杆菌(Psychrobacter sp.),肠杆菌(Enterobacter sp.)。通过对微生物膜污损细菌进行发酵培养,结合天然产物分离纯化和核磁共振鉴定技术,共从发酵液中分离并鉴定了9种次级代谢产物,其中4种是二酮哌嗪(Diketopiperazine,DKP)类信号分子,环(脯氨酸-甘氨酸)(1),环(脯氨酸-丙氨酸)(2),环(4-羟基-脯氨酸-亮氨酸)(3),环(脯氨酸-酪氨酸)(4),以及尿嘧啶(5),胸腺嘧啶(6),对羟基苯乙醇(7),十五烷酸(8),邻苯二甲酸二(2-乙基己)酯(9)。研究结果表明,烟台海域污损微生物膜中细菌组成多样,以假交替单胞菌和芽孢杆菌为主;污损细菌产生了多种代谢物,其中包括4种DKP类信号分子,该类物质可能对生物污损的发生具有调控作用,为探究生物污损和生物膜的作用机制奠定了基础。