The distribution of corrosive acidic compounds in petroleum fractions

Because the acidic compounds of the feedstock of T refinery (FTAC) have special high corrosivity, the composition and class distribution of the acidic compounds were analyzed by electrospray ionization Fourier transform ion cyclotron resonance mass spectroscopy, and compared with the acidic compounds of the lubrication distillation fraction from D refinery and commercial naphthenic acids. This study indicates that the feature of FTAC is exceptionally high proportion of acyclic carboxylic acids, aromatic acids, and alkylphenol-like compounds, which are some of the reasons for the high corrosivity of the feedstock of T refinery.     

3种类型石油酸的腐蚀性以及相互影响

以相对分子质量相近的正辛酸、环己基乙酸和苯甲酸为模型石油酸,采用SEM、X射线能谱和拉曼光谱等手段,分析了相同酸值(2.3 mgKOH/g)下各种石油酸模拟油全浸静态腐蚀实验后的试片和模拟油的形貌和组成,探究了不同类型石油酸的腐蚀特性和相互影响.结果表明:在190℃静态腐蚀实验中,腐蚀速率由大到小的顺序依次为环烷酸、芳...     

Visualization of imbibition in porous media by environmental scanning electron microscopy: application to reservoir rocks

The study of wettability and fluid distribution in porous media has been approached by means of environmental scanning electron microscope (ESEM). This method allows visualization of rock samples in the presence of fluids (both oil and brine). Fluids consisted of water and dodecane, which remain liquid under the observation conditions. Porous media consisted of homogeneous wettability sintered glass, and mixed wettability reservoir rock samples: a sandstone from the North Sea and a carbonate from the Middle East (preserved state). For sintered glass, (treated with octadecyltrichlorosilane to obtain an oil-wet surface), after the sample was saturated with water (nonwetting fluid), it was clearly possible to follow its appearance at the upper face of the core sample. For the sandstone samples, it was possible to observe the rise of oil through the water phase at the junction between quartz and kaolinite. For carbonate samples, tentative correlations were made between the appearance of oil at the upper face and the pore structure of the sample.     

运用高压压汞及扫描电镜多尺度表征致密砂岩储层微纳米级孔喉特征——以渤海湾盆地沾化凹陷义176区块沙四段致密砂岩储层为例

选取渤海湾盆地沾化凹陷义176区块沙河街组四段32块致密砂岩样品进行高压压汞、覆压孔渗等实验,结合环境扫描电镜的镜下特征,探讨致密砂岩储层的微观孔喉结构特征及其渗透性,特别是流体在纳米级及微米级喉道的渗流特征。实验表明：研究区的排替压力分布范围大,结合孔喉的分布情况和渗透率的相对大小,将该区的储层分成4大类6亚类;dv/d（logd）能够准确形象地反映各级孔喉分布情况,结合环境扫描电镜对孔喉相对大小的识别结果,将研究区的孔喉体系分为纳米级、微纳米级、纳微米级及微米级等4类,将喉道分为纳米级喉道和微米级喉道;通过相关性分析,发现纳米级喉道控制着渗透率,而微米级喉道更多贡献于孔隙度;高压压汞在研究致密储层的孔喉特征时,不仅能够表征常规孔喉的结构特征,同时也能反映微纳米级孔喉的大小及流体在其中的渗流特征,对进一步精细评价储层具有良好效果。     

Study of wettability and spreading impact in three-phase gas injection by cryo-scanning electron microscopy

Much has been already done and written on the effect of wettability and spreading in three-phase displacement properties and efficiency. However, a direct visualization of the impact of these parameters in the distribution of the three fluids (water–oil–gas) within the pore space and consequently on the recovery mechanisms has been lacking. The objective of this paper is to obtain at the pore scale the necessary information to interpret the macroscopic behavior and to predict ultimate oil recovery for well controlled wetting and spreading conditions. To this end cryo-scanning electron microscopy (cryo-SEM) observations are performed in water-wet and oil-wet Fontainebleau sandstone plugs for spreading and non-spreading conditions. It is demonstrated that cryo-SEM can be used as a tool to study at the pore scale the fluid distributions and efficiency of oil recovery processes involving three phases. It is also proved that in a real porous medium both wettability and spreading affect gas injection efficiency by controlling three-phase distributions at the pore level and phase connectivity.     

激光扫描共聚焦显微分析技术表征页岩亚微米级孔隙中的含油性——以准噶尔盆地芦草沟组页岩为例

亚微米级孔隙及其含油性是页岩油勘探开发所需的重要信息。为应用激光扫描共聚焦显微镜有效观测亚微米级孔隙的含油性,修改了激光扫描共聚焦显微镜主分光器和检测器的前置滤光片配置,使之能较好地进行反射光和荧光联合扫描,消除矿物所发荧光的干扰,实现了亚微米级孔隙及其含油性的精确观测。该方法在准噶尔盆地吉木萨尔凹陷芦草沟组页岩油研究中进行了应用,发现了大量的亚微米级含油孔隙;页岩油多呈不规则形状、斑块状和星点状。这套页岩的有机质成熟度R_o为0.6%~1.1%,平均约为0.9%,但轻、重质组分的分布具有显著的非均一性,不完全受成熟度控制。在有些部位,轻质组分含量及其与重质组分的比值均较高,但在成熟度相近甚至稍高的邻近部位,却存在以重质组分为主的情况。页岩层系内部的油气运移也是一个重要的控制因素。页岩中的轻质和重质组分的观测与分布规律研究,对于页岩油勘探开发十分重要,激光扫描共聚焦显微新技术可成为重要的观测手段。     

鄂尔多斯盆地华池地区延长组7段页岩油储层孔隙结构特征及控制因素

为明确有机质及矿物成分对鄂尔多斯盆地延长组7段（长7段）泥页岩储层孔隙结构的影响,利用氩离子抛光—场发射扫描电镜、低压氮气吸附实验,表征长7段泥页岩储层孔隙结构特征,并结合全岩矿物组分及有机地球化学实验,分析长7段泥页岩孔隙结构的主控因素。结果表明：长7段泥页岩主要发育黏土矿物晶间孔、粒间孔,可见少量有机质孔、溶蚀孔及微裂缝,其氮气吸附等温线均为Ⅱ型等温线,兼具有H₃及H₄型滞后环特征,表明泥页岩孔隙的中孔较为发育,孔隙形态呈平行片状及墨水瓶状。泥页岩孔隙结构受控于有机质、黏土矿物、石英、长石和黄铁矿,其中黏土矿物相转化在其矿物晶体层间形成大量微孔及中孔,是研究区泥页岩孔隙的主要来源;有机质生成的液态烃和固体沥青及自形单晶黄铁矿充填无机矿物孔隙,一定程度上减少了长7段泥页岩的孔隙空间。研究结果可以为认识长7段泥页岩孔隙结构特征及控制因素提供新的参考。