The occurrence and distribution of phenylphenanthrenes,phenylanthracenes and binaphthyls in Palaeozoic to Cenozoic shales from China

The distributions of phenylphenanthrenes, phenylanthracenes and binaphthyls in sediment extracts have been investigated in a set of lacustrine shales from the Eocene Shahejie Formation (well SG 1) in the western Depression of Liaohe Basin, East China. All isomers of these phenyl substituted polycyclic aromatic hydrocarbons (PAHs) have been identified in the m/z 254 mass chromatograms by comparison of the mass spectra and standard retention indices with those published elsewhere. The 2,2′-binaphtyl/1,2′-binaphthyl ratio values show a linear increase with increasing maturity, and have a good correlation with T_max (°C). Therefore, they can be used as an effective maturity indictor for source rocks in this study. In the main phase of the oil generation window, the 3-phenylphenanthrene and 2-phenylphenanthrene prevail over other isomers, and some thermodynamically unstable isomers including all phenylanthracenes, 4-phenylphenanthrene and 1,1′-binaphthyl are present at very low concentrations or below the detection limit in the m/z 254 mass chromatograms. The absolute concentrations of individual phenylphenanthrene and binaphthyl isomers were obtained by comparison of the peak areas with that of internal standard phenanthrene-d10. All isomers are present at low concentrations at low maturity stages and then show an abrupt increase at a depth of ≈3100 m, corresponding to the onset of the intensive C₁₅₊ hydrocarbon generation. The Phenylphenanthrene Ratio (2- + 3-PhP)/[(2- + 3-PhP) + (4- + 1- + 9-PhP)] shows a reverse change with increasing maturity at the low maturity stage. It displays a drastic increase at a depth of ≈3100 m and then remains at a nearly constant value. This study can expand the understanding of the formation and distribution of phenyl substituted PAHs in sedimentary organic matter deposited in various environments.     

阵列式探地雷达信号极化场特征

阵列式观测是探地雷达系统研制和新型探测方法的一个重要发展趋势,而同形多源并发地下目标响应特征分析成为系统研制和数据处理研究的基础和前提。阵列式天线的多源并发信号及目标反射信号存在复杂的极化特性,但同时也包含更多目标特征的响应信息。本文针对基于似平面波探地雷达系统,分析了目标体在极化平面波照射下的响应特征,从多极化信号角度分析典型地下目标体形态特征;并采用时域有限差分正演分析方法,通过对阵列天线接收到的数据沿时间轴进行积分来获得目标在地表投影的分布情况,分析了一维及二维分布的收发天线阵列对目标的检测。研究成果表明,多极化综合特征分析能够有效改善目标检测的稳定性,提高目标响应信号的信噪比,减弱天线方向图和目标散射截面闪烁对数据剖面的影响,降低数据处理和解释的难度。     

Estimating the contribution of glacial meltwater to Ranwu Lake,a proglacial lake in SE Tibet,using observation data and stable isotopic analyses

It is important for both current monitoring and paleoenvironmental research conducted on proglacial lakes and their adjacent glaciers to clarify the hydrological processes operating on these lakes. However, in remote regions with limited accessibility it may be difficult to study hydrological processes by direct monitoring. In this study, we use measurements of stable isotopic compositions to trace the multiple water sources contributing to Ranwu Lake, a proglacial lake in south-eastern Tibet. Using stable isotopic data from precipitation, inflowing rivers and the lake water, a water and isotope mass balance modelling method was used to calculate the ratio of evaporation to input. Subsequently, using hydrological and climatic data for the outflow, the largest inflow and precipitation, other hydrological elements of the lake water balance were also calculated. The results demonstrate that the ratio of evaporation to inflow is as low as 0.009, the lowest value observed for the Tibetan Plateau, indicating that Ranwu Lake is a through-flow lake with a very short retention time. Glacial meltwater accounts for at least 55% of total runoff, the highest value observed for the Tibetan Plateau, indicating that the sediments of Ranwu Lake may have considerable potential for reconstructing variations in the activity of the local glaciers. Finally, we note that it may be inappropriate in this glacier-fed lake to use the intersection of the local meteoric water line with the lake water line for determining the isotopic composition of the input water, and this possibility must be carefully considered when stable isotope mass modelling is used in proglacial lakes.     

Improved discrete element modeling for proppant embedment into rock surfaces

Brinell indentation tests were performed on Montney siltstone, and the results were compared with discrete element indentation simulations that use the micro-parameters calibrated using compression test data from the same siltstone samples. The simulated proppant indentation into the rock surface can be 15% less than the laboratory measurements. A lower effective particle–particle modulus and thus a lower Young’s modulus are needed in discrete element models for proper simulation of indentation. An equation to find the appropriate value of Young’s modulus for indentation simulation is proposed using Brinell indentation tests including 198 laboratory tests and 32 discrete element simulations. This equation can improve the prediction of Young’s modulus and thus the particle–particle effective modulus for indentation simulations to match the measured force–indentation depth curve in the laboratory. Using the improved micro-parameters, a parametric analysis of the influence of rock Young’s modulus and proppant particle size on proppant embedment was performed. An equation to estimate Brinell hardness as a function of Young’s modulus and closure stress was derived. A practical procedure was developed to predict proppant embedment from the estimated hardness. The predictions agree with the laboratory measurements in a case study on the Montney Formation.

     

碎屑岩成像测井沉积学研究及其在海上油田的应用

基于成像测井技术在我国海域含油气盆地的应用积累,提出了碎屑岩成像测井沉积学的概念。碎屑岩成像测井沉积学的主要研究内容包括地层岩性识别、沉积构造解释、沉积序列与微相分析、砂体物源与古流向分析、砂体分布预测等五个方面。利用南海西部的实际资料,运用成像测井技术,对五方面的应用逐一分析或提出了应用前提、使用步骤、注意要点、已有规律特征以及典型实例。