基于低场核磁共振的抚顺油页岩孔隙连通性演化研究

油页岩原位注热开采过程中，储层内部孔隙结构的连通性直接影响载热介质的流动行为和传热效率，同时对油气产物的扩散和流动行为起控制作用.本文利用低场核磁共振（LF NMR）技术，考察了不同热解终温（23~650℃）处理时，饱和水及束缚水状态下抚顺油页岩的T₂谱，分析了可动流体T₂截止值、束缚流体孔隙度、饱和流体孔隙度、渗透率等NMR孔隙参数，定量研究了随热解终温升高，抚顺油页岩孔隙结构的连通性演化规律.研究结果表明热解终温对抚顺油页岩孔隙连通性及渗透率的变化起控制作用，且可动流体孔隙度对总孔隙度的增加起主要促进作用，这说明热解终温升高加大了渗透率及油气产物的输运能力.本文为深入认识油页岩原位热解过程中孔隙结构的演化提供了依据.     

CO2-水-页岩相互作用的研究现状及展望

简要综述了CO2、水和页岩间矿物的相互作用,分析了CO2注入到地下进入页岩层后,地下含水层pH值的变化,并根据页岩层的矿物学组成分为黏土矿物和脆性矿物,较为详细地描述了CO2与黏土矿物和脆性矿物之间发生的地球化学反应,概述了此反应对页岩层孔隙度和渗透率的影响。同时,也讨论了CO2增强页岩气开采的现实问题及发展趋势,为今后的研究提供了参考。     

页岩气和致密砂岩气藏微裂缝气体传输特性

页岩气和致密砂岩气藏发育微裂缝,其开度多在纳米级和微米级尺度且变化大,因此微裂缝气体传输机理异常复杂.本文基于滑脱流动和努森扩散模型,分别以分子之间碰撞频率和分子与壁面碰撞频率占总碰撞频率的比值作为滑脱流动和努森扩散的权重系数,耦合这两种传输机理,建立了微裂缝气体传输模型. 该模型考虑微裂缝形状和尺度对气体传输的影响. 模型可靠性用分子模拟数据验证.结果表明:(1)模型能够合理描述微裂缝中所有气体传输机理,包括连续流动,滑脱流动和过渡流动;(2)模型能够描述不同开发阶段,微裂缝中各气体传输机理对传输贡献的逐渐变化过程;(3)微裂缝形状和尺度影响气体传输,相同开度且宽度越大的微裂缝,气体传输能力越强,且在高压和微裂缝大开度的情况下表现更明显.      

Evaluation of Oil Yield of Oil Shale by Infrared Spectrometry Coupled with Ultrasound-assisted Extraction

The oil yield of oil shale was evaluated by Fourier transform infrared(FTIR) spectrometry coupled with ultrasound-assisted extraction. The extraction conditions, including the amount of sample, extraction time and extraction temperature, were examined and optimized. Twenty-four oil shale samples were collected and divided into calibration set and prediction set randomly with a ratio of 2:1. The oil yields of all the samples were determined by the routine method(low-temperature retorting) for reference. The linear regression(LR) equations of oil yield vs. the total area of the spectrum peaks in a wavenumber range of 3100-2800 cm^-1 as well as the sum of absorbance of three absorption peaks(2855, 2927 and 2955 cm^-1), and the multiple linear regression(MLR) model of oil yield vs. the absorbances of the three absorption peaks were constructed with the samples in calibration set and applied to the evaluation of the oil yields of the samples in prediction set, respectively. The results show that the MLR model provides more accurate predictions than the other LR two equations. The determination coefficient(R_p²), the root-mean-square error of prediction(RMSEP) and the residual prediction deviation(RPD) of the MLR model are 0.9616, 0.6458 and 3.6, respectively. The present method is a rapid and effective alternative to the routine low-temperature retorting method.     

钻井完井液浸泡弱化页岩脆性机制

页岩脆性是页岩地层钻井、水力压裂设计的关键参数之一,目前针对钻井过程中工作液浸泡对页岩脆性的影响还未引起关注.通过开展钻井完井液浸泡前后页岩三轴力学实验,利用脆性评价模型分析了页岩脆性变化特征.结果表明,延长组页岩脆性强于龙马溪组页岩;油基和水基钻井完井液浸泡均能导致页岩脆性降低,且油基钻井完井液浸泡后的页岩脆性降低幅度更大;龙马溪组页岩浸泡后脆性减弱幅度较延长组页岩大.页岩脆性弱化机制包括:(1)由层理面胶结强度不同引起的脆性强弱差异;(2)由毛管自吸作用导致的高孔压、高应力强度因子、低临界断裂韧性;(3)由碱液侵蚀导致的页岩溶蚀孔形成及矿物颗粒碎裂;(4)由黏土矿物水化膨胀产生的膨胀应力;(5)由钻井完井液滤液润滑导致的页岩破裂面摩擦系数降低.延长组页岩层理面强度较龙马溪组页岩低,导致延长组页岩脆性强于龙马溪组页岩.其次,和水基钻井完井液相比,油基钻井完井液具有更大的自吸量、更高的pH值、更强的润滑性,因此,油基钻井完井液浸泡降低页岩脆性幅度更大.另外,由于龙马溪组页岩具有更小的润湿角、更强的毛管自吸和碱液侵蚀作用,相同浸泡条件下,龙马溪组页岩脆性降低幅度更大.本研究可为页岩地层钻井液性能优化、井壁稳定控制、水力压裂设计等提供理论指导.      

页岩气储层压裂数值模拟技术研究进展

页岩气储层水力压裂数值模拟既要考虑页岩储层岩石的特性,又要兼顾水平外分段压裂施工工艺,是一个非常棘手的力学难题.本文简述了页岩气储层岩石具有的地质力学特征和页岩气储层开发常用的水平井分段压裂技术;详述了扩展有限元、边界元、离散元在水力压裂裂缝模拟上的应用现状,指出了它们在处理裂缝问题的局限性和优越性,总结出边界元三维位移不连续法是模拟多裂缝扩展的有效方法.     

水岩化学作用对黑色页岩的化学损伤及力学劣化试验研究

为模拟黑色页岩化学风化中酸性水-页岩化学作用过程,本文对其进行氧化条件下的不同pH值H2SO4溶液的非平衡流动态腐蚀性试验,获得了黑色页岩化学腐蚀前后矿物变化、相对质量损失、次生孔隙率、纵波波速变化及微观结构特征的变化。通过单轴压缩试验,获得黑色页岩在不同浸泡时段的变形和强度特性规律,探讨了酸性水对黑色页岩化学作用的化学损伤和力学劣化的腐蚀效应及机制。研究表明,页岩试件在化学腐蚀后,易溶性矿物成分减小,黏土矿物增加,同时矿物胶结变得松散,矿物边缘变得模糊;页岩试件的相对质量损失与次生孔隙率随pH值减小和浸泡时间的增长而增大,而纵波波速则减小;其力学特性有从脆性破坏向延性破坏转化的趋势,单轴抗压强度和弹性模量有随pH值减小和浸泡时间的增长而减小的趋势。基于次生孔隙率,构建化学损伤变量来描述试件化学-力学损伤演化过程。分析酸性水-页岩化学作用的机理主要为:溶解作用、氧化作用、水解作用及离子交换吸附作用。     

Removal of Chromium(VI) from Groundwater Using Oil Shale Ash Supported Nanoscaled Zero-valent Iron

Oil shale ash(OSA) supported nanoscaled zero-valent iron(OSA-nZVI) was used as a rapid and efficient reductant for Cr(VI) reduction. The optimal mass ratio of nZVI to OSA and the optimal dosage were explored. The effects of initial pH, reaction temperature, initial Cr(VI) concentration, and common cations and anions in groundwater on Cr(VI) reduction were determined in batch experiments. The results show that the optimum initial pH is 5.0. The reaction temperature has a positive effect on Cr(VI) reduction while the real groundwater has a negative effect. Additionally, 84.22% Cr(VI) was still reduced by 3 g/L OSA-nZVI(1:2)(mass ratio of OSA to Fe⁰ was 1:2) within 120 min for 50 mg/L Cr(VI) under conditions of 10℃ and unadjusted pH.     

油页岩含油率近红外光谱原位分析方法研究

为实现油页岩含油率的原位检测,采用便携式近红外光谱分析技术,针对吉林扶余油页岩基地2号钻井的66个岩芯样品开展了原位检测的分析建模方法研究。采用自制便携式近红外光谱仪器获得反射率、吸光度、K-M函数三种数据形式光谱数据,结合主成分-马氏距离(PCA-MD)剔除异常样品、无信息变量消除法(UVE)波长筛选及二者组合的四种建模数据优化方法,采用相同的数据预处理方法进行偏最小二乘(PLS)和反向传播神经网络(BPANN)两种方法的建模分析研究,确定最佳分析模型及方法。结果表明(1)不论是否采用四种不同的数据优化方法,两种建模方法所用建模数据库适合采用反射率或K-M函数的光谱数据形式;(2)两种建模方法,采用四种不同的数据优化方法,对相同数据库建模精度的影响不同：采用PLS建模方法、以PCA-MD和UVE+ PCA-MD两种方法进行数据优化、可以提高K-M函数光谱数据形式数据库的建模分析精度,采用BPANN建模方法、以UVE、PCA-MD 与UVE组合的 三种方法进行数据优化、对三种数据形式数据库的建模精度均有所提高;(3)除以反射率光谱数据并进行PCA-MD数据优化外,采用BPANN方法的建模精度好于PLS法。其中采用反射率光谱数据形式、只进行UVE数据优化外的BPANN建模精度最高,预测相关系数为0.92、标准偏差为0.69%。     

Kinetics of combustion of oil shale with polystyrene

The combustion kinetics of Göynük oil shale, polystyrene and several polystyrene-oil shale blends were investigated by thermogravimetric analysis in the present study. Experiments were conducted at non-isothermal conditions with a heating rate of 5, 10 and 20 K min^?1 in the 298–1173 K temperature interval under an air atmosphere. Differential thermogravimetric data were analyzed by two different models. Effects of blending ratio of oil shale and polystyrene and heating rate on the combustion kinetics were investigated. Kinetic parameters were determined and the results were discussed.