藏南日喀则地区白垩纪泥岩、页岩有机质丰度及其油气地质意义

对藏南发育完整的、厚度巨大的海相白垩纪地层中的暗色泥、页岩开展了有机质丰度研究。综合分析结果表明：该区泥、页岩中残余有机碳含量在0.05%-1.1%之间,平均值约为0.42%,其中下白垩统约为0.531%,上白垩统约为0.265%,有机碳平均含量变化特征与该区的古地理格局及海平面升降有关。氯仿沥青‘A’含量在0.0009%-0.0072%之间,平均含量约为0.0040%。有机碳与氯仿沥青‘A’最大值与最小值之比分别为22和8。有机碳与氯仿沥青‘A’这种弱负相关性与两者遭受剧烈的地表风化作用、强烈的紫外线照射和高程度有机质热演化后的损失量有关,后者远大于前者。白垩系残余有机碳含量大于0.6%的中等—好生油岩样10件,占样品总数的27%,下白垩统样品9件,占样品总数的24.3%,上白垩统样品1件,占样品总数的2.7%,表明来自北喜马拉雅地区东山组和康马—隆子地区甲不拉组的早白垩世泥、页岩为该区主要的有效生油岩。

泥、页地层中钻井冲洗液的应用研究

对苏南钻井经常遇到的泥、页岩地层特征进行研究,利用实验和对比分析的方法,提出冲洗液方案,并对该类地层中钻井冲洗液的作用机理和特点进行分析。在苏南临湖和石湖等地复杂地层地热钻井施工中,冲洗液的应用效果较好,孔壁稳定,钻孔质量好,钻进效率高。可以作为苏南地区泥、页岩地层地热钻井冲洗液应用参考。

Lower Es3 in Zhanhua Sag, Jiyang Depression： a case study for lithofacies classification in lacustrine mud shale

Oil and gas exploration in lacustrine mud shale has focused on laminated calcareous lithofacies rich in type Ⅰ or type Ⅱ1 organic matter, taking into account the mineralogy and bedding structure, and type and abundance of organic matter. Using the lower third member of the Shahejie Formation, Zhanhua Sag, Jiyang Depression as the target lithology, we applied core description, thin section observations, electron microscopy imaging, nuclear magnetic resonance, and fullbore formation microimager （FMI） to study the mud shale lithofacies and features. First, the lithofacies were classified by considering the bedding structure, lithology, and organic matter and then a lithofacies classification scheme of lacustrine mud shale was proposed. Second, we used optimal filtering of logging data to distinguish the lithologies. Because the fractals of logging data are good indicators of the bedding structure, gamma-ray radiation was used to optimize the structural identification. Total organic carbon content （TOC） and pyrolyzed hydrocarbons （S2） were calculated from the logging data, and the hydrogen index （HI） was obtained to identify the organic matter type of the different strata （HI vs Tmax）. Finally, a method for shale lithofacies identification based on logging data is proposed for exploring mud shale reservoirs and sweet spots from continuous wellbore profiles.

Coupled effects of stress damage and drilling fluid on strength of hard brittle shale

During well drilling process,original stress state of hard brittle shale will be changed due to stress redistribution and concentration,which leads to stress damage phenomenon around the borehole.Consequently,drilling fluid will invade into formation along the tiny cracks induced by stress damage,and then weaken the strength of hard brittle shale.Based on this problem,a theoretical model was set up to discuss damage level of shale under uniaxial compression tests using acoustic velocity data.And specifically,considering the coupled effect of stress damage and drilling fluid,the relationship between hard brittle shale strength and elapsed time was analyzed.

Analysis of the mechanical property of mudstone/shale in paralic coal measures and its influence factors

The mechanical property of mudstone/shale in coal measures is a key factor of engineering mechanics that influences the development of shale gas. A rock mechanics test was performed in order to analyze the complete stress-strain mechanic characteristics and influence factors of mudstone/shale in paralic coal measures, from the Carboniferous-Permian periods in a coal field of Northern China. The relationship between the mechanical properties of mudstone/shale in coal measures, and its chemical component, water content are established, and their models are constructed. Research results show that mud- stone/shale has low mechanical strength, low elastic modulus and a high Poisson＇s ratio. The complete stress-strain curve has apparent elastoplastic deformation characteristics, and after reaching peak strength, it exhibits obvious strain softening characteristics. The uniaxial compressive strength of mudstone/shale and its elastic modulus increases exponentially with the increase of SiO2 content, and as the ignition loss increases, the uniaxial compressive strength and elastic modulus of mudstone/shale will decrease according to the law of power function. The compressive strength of mudstone/shale and its elastic modulus will decrease with the increase of water content in mudstone/shale.

Geological characteristics and shale gas distribution of carboniferous mudstones in the Tarim Basin,China

Extant research on Paleozoic mudstone is well developed in the Tarim Basin, while the research on Carboniferous mudstone is relatively weak. Through systematic study of lithology, geochemical characteristics,reservoir characteristics and gas–bearing properties of Carboniferous mudstone in the Tarim Basin, this study aims to provide a geological basis for the Paleozoic shale gas exploration and development, favorable zone optimization, and resource potential evaluation in the Tarim Basin. The results show that the sedimentary environments of organic-rich mudstone in the study area were mainly basin facies and slope facies. Lithology is dominated by black carbonaceous mudstone, followed by calcareous mudstone, siliceous mudstone, and siliceous rocks. Mudstone is mainly developed in the Kalashayi Formation,which is located in the Bachu and Markit slope belt, with the cumulative thickness of 30–200 m. The organic carbon content is commonly more than 0.4%, and the organic matter types are type II and type III. Thermal evolution degree is widely distributed from a low mature to over mature stage, and different tectonic units have a greater difference. The contents of quartz plus feldspar are between 12% and 82.5%, with an average of 45.8%. Thecontent distribution of clay mineral is from 12% to 57%,with an average of 38.2%. Carbonate minerals(mainly siderite) content is below 50%. The brittle mineral content of the mudstone is approximately 65%, with a strong compressibility, and the mudstone has the material basis of forming crack and natural fracture. Microscopic pores in micro–nanometer level are well developed in the mudstone, including micro bedding joint, microcrack,interbedded pores of clay mineral, nanoscale intragranular or edge pores in the massive organic matter, bioclastic micropores, and mineral dissolution pores, etc. According to the standards provided by the Ministry of Land and Resources in China, the Kalashayi Formation in Bamai Area is a favorable area for shale gas development.

Effect of distortion degree on the hydration of red mud base cementitious material

The interaction of Si anions with Al sites during the hydration process was observed by NMR, IR and SEM to understand the reaction mechanism of the hydrates formation mixed with oil shale calcined at different temperatures. As the reaction progressed, the coordination of Al （Ⅳ, Ⅴ, and Ⅵ） changed almost completely to Ⅳ, when mixed with oil shale calcined at 700 ℃. However, when mixed with oil shale calcined at 400 ℃, some 6-coordination of Al still remained in the hydrates. Under the function of alkaline solutions, which were produced with the hydration of clinker, a certain amount of Si and Al atoms dissolved or hydrolyzed from aluminosilicate, formed geomonomers in solutions, and then polycondensed to form networks.