地下水位波动及降水对原油在非均质土层中重分布的影响
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摘要
为研究原油泄漏后在非均质土层中的重分布过程及影响因素,建立3种不同组合的非均质土层物理模型(编号分别为L-a、L-b、L-c)进行原油泄漏后重分布过程的室内模拟,分别代表局部非渗透性透镜体(浅层泄漏)、大面积弱渗透性粉质亚黏土(内部泄漏)和土层界面(浅层泄漏)存在条件.待原油重力渗透稳定后分别进行升降水位和降水的模拟试验,由PET聚酯膜绘制、CCD相机拍摄和基于CMYK的灰度分析等图像采集和分析法获得平面运移分布图、纵剖面灰度变化图,采用风干法和紫外分光光度法获得采样点含水率和含油率对比图,分析原油泄漏后在非均质土层中的运移规律.结果表明:①在水位波动下,局部非渗透性透镜体和大面积粉质亚黏土弱透水层可有效截获原油,使原油在其左右及上侧大量聚集; 3组试验中原油的重分布过程以垂向运移为主,但在粗-细界面和细-粗界面会因油水驱替和毛细压力导致其部分横向运移.②模拟降水时,受到淋滤和水位波动的综合效应,原油油聚区不能在短时间内随水位线移动,体现其滞后性;在模拟降水结束后油聚区大量分布于水位线位置和细-粗界面处;降水对土壤中的原油具一定稀释作用.③L-a和L-c组表层泄漏的原油分布面积(分别为800、538 cm~2)较大,采样点含油率极差(分别为6. 23%、6. 80%)较大;而L-b组内部泄漏的原油分布面积(235 cm~2)较小,采样点含油率极差(2. 99%)较小.研究显示,地下水位波动及降水对非均质土层中原油的周期性聚集和释放有一定影响,尤其是局部非渗透性透镜体、大面积弱渗透性粉质亚黏土及岩性界面存在土层中影响更大.
In order to study the redistribution process and influencing factors in heterogeneous soil after crude oil spill,three physical models of heterogeneous soil layers were established indoor( No. L-a,L-b,L-c respectively) to simulate the redistribution processes of crude oil after spill,which represented the conditions of the local impermeable lens( shallow leakage),the extensive low permeability silty clay layer( internal leakage) and soil layer interfaces( shallow leakage). The simulated experiments of rainfall,water table rise and fall were carried out respectively after the gravity infiltration of crude oil became stable. The plane migration distribution maps and the longitudinal profile grayscale variation graphs were obtained by image acquisition and analysis methods such as drawing on the PET polyester film,photography and the gray analysis based on CMYK. The contrast diagrams between water content and oil content at sampling points were obtained by air dry and ultraviolet spectrophotometry method respectively. Then the migration patterns of the crude oil in the heterogeneous soil layer were analyzed. The results showed that:( 1) With the fluctuation of water table,the local impermeable lens and the extensive low permeability silty clay layer could effectively intercept the crude oil,causing crude oil to accumulate on the top and sides of them. The redistribution processes of the oil in L-a,L-b and L-c test groups were dominated by vertical migration,but the oilwater displacement and capillary pressure caused some crude oil to move horizontally at the fine-coarse interface.( 2) In the case of simulated rainfall,the oil accumulation zone was often unable to follow the water table in short time because of the comprehensive effects of leaching and water table fluctuation,which reflected the hysteresis. At the end of the simulated rainfall,the oil accumulation areas were located at the water table and the fine-coarse interface. And the rainfall resulted in dilution of the crude oil to a certain degree.( 3) The crude oil distribution areas in L-a and L-c test groups( 800 cm~2 and 538 cm~2 respectively) were larger than in the L-c( 235 cm~2). The L-a and L-c were both under the conditions of surface leakage while the L-b group had internal leakage. After the tests,the oil content in different sampling points in L-a and L-c( 6. 23% and 6. 80% respectively) were bigger than in L-b( 2. 99%). The comprehensive results indicate that the underground water table fluctuation and rainfall have influence on periodical accumulation and release of crude oil in the heterogeneous soil layers,especially in the presence of local impermeable lens,the extensive low permeability silty clay and lithologic interface.
In order to study the redistribution process and influencing factors in heterogeneous soil after crude oil spill,three physical models of heterogeneous soil layers were established indoor( No. L-a,L-b,L-c respectively) to simulate the redistribution processes of crude oil after spill,which represented the conditions of the local impermeable lens( shallow leakage),the extensive low permeability silty clay layer( internal leakage) and soil layer interfaces( shallow leakage). The simulated experiments of rainfall,water table rise and fall were carried out respectively after the gravity infiltration of crude oil became stable. The plane migration distribution maps and the longitudinal profile grayscale variation graphs were obtained by image acquisition and analysis methods such as drawing on the PET polyester film,photography and the gray analysis based on CMYK. The contrast diagrams between water content and oil content at sampling points were obtained by air dry and ultraviolet spectrophotometry method respectively. Then the migration patterns of the crude oil in the heterogeneous soil layer were analyzed. The results showed that:( 1) With the fluctuation of water table,the local impermeable lens and the extensive low permeability silty clay layer could effectively intercept the crude oil,causing crude oil to accumulate on the top and sides of them. The redistribution processes of the oil in L-a,L-b and L-c test groups were dominated by vertical migration,but the oilwater displacement and capillary pressure caused some crude oil to move horizontally at the fine-coarse interface.( 2) In the case of simulated rainfall,the oil accumulation zone was often unable to follow the water table in short time because of the comprehensive effects of leaching and water table fluctuation,which reflected the hysteresis. At the end of the simulated rainfall,the oil accumulation areas were located at the water table and the fine-coarse interface. And the rainfall resulted in dilution of the crude oil to a certain degree.( 3) The crude oil distribution areas in L-a and L-c test groups( 800 cm~2 and 538 cm~2 respectively) were larger than in the L-c( 235 cm~2). The L-a and L-c were both under the conditions of surface leakage while the L-b group had internal leakage. After the tests,the oil content in different sampling points in L-a and L-c( 6. 23% and 6. 80% respectively) were bigger than in L-b( 2. 99%). The comprehensive results indicate that the underground water table fluctuation and rainfall have influence on periodical accumulation and release of crude oil in the heterogeneous soil layers,especially in the presence of local impermeable lens,the extensive low permeability silty clay and lithologic interface.
引文
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[7]LARI S K,DAVIS G B,JOHNSTON C D.Incorporating hysteresis in a multi-phase multi-component NAPL modelling framework:a multi-component LNAPL gasoline example[J].Advances in Water Resources,2016,96(10):190-201.
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[11]李洪,李鑫钢,徐世民,等.饱和区中非水相有机物溶解的实验研究[J].化学工程,2008,36(4):49-52.LI Hong,LI Xingang,XU Shimin,et al.Experimental study of nonaqueous phase liquids dissolution in saturated zone[J].Chemical Engineering(China),2008,36(4):49-52.
[12]李慧颖,杜晓明,伍斌,等.NAPLs污染物指进锋面形态的指间距离预测[J].环境科学研究,2013,26(8):844-850.LI Huiying,DU Xiaoming,WU Bin,et al.Prediction of finger spacing for NAPLs infiltrated in porous media[J].Research of Environmental Sciences,2013,26(8):844-850.
[13]朱振慧,高宗军,张晓海,等.轻质非水相流体(柴油)在多孔介质中的垂向运移[J].环境工程学报,2015,9(4):1842-1848.ZHU Zhenhui,GAO Zongjun,ZHANG Xiaohai,et al.Vertical migration of LNAPLs(diesel)in porous medium[J].Chinese Journal of Environmental Engineering,2015,9(4):1842-1848.
[14]林广宇.地下水位变动带石油烃污染物的迁移转化规律研究[D].长春:吉林大学,2014:55-56.
[15]KECHAVARZI C,SOGA K,ILLANGASEKARE T H.Twodimensional laboratory simulation of LNAPL infiltration and redistribution in the vadose zone[J].Journal of Contaminant Hydrology,2005,76(3):211-233.
[16]WANG W,KUO T,CHEN Y,et al.Effect of precipitation on LNAPL recovery performance:an integration of laboratory and field results[J].Journal of Petroleum Science and Engineering,2014,116(4):1-7.
[17]LENHARD R J,RAYNER J L,DAVIS G B.A practical tool for estimating subsurface LNAPL distributions and transmissivity using current and historical fluid levels in groundwater wells:effects of entrapped and residual LNAPL[J].Journal of Contaminant Hydrology,2017,205(10):1-11.
[18]DATRY T,MALARD F,VITRY L,et al.Solute dynamics in the bed sediments of a stormwater infiltration basin[J].Journal of Hydrology,2003,273(1):217-233.
[19]CLASS H,HELMIG R,NEUWEILER I.Sequential coupling of models for contaminant spreading in the vadose zone[J].Vadose Zone Journal,2008,7(2):721-731.
[20]韩彬,曹磊,郑立,等.综合模拟风化条件下渤海原油中生物标志物及多环芳烃风化规律研究[J].分析测试学报,2010,29(9):871-877.HAN Bin,CAO Lei,ZHENG Li,et al.Weathering disciplinarian of biomarkers and pahs in crude oil from bohai sea under comprehensive simulation[J].Journal of Instrumental Analysis,2010,29(9):871-877.
[21]国家海洋局.GB 17378.5-2007海洋监测规范第5部分:沉积物分析[S].北京:中国标准出版社,2007.
[22]MILLER C D,DURNFORD D S,FOWLER A B.Equilibrium nonaqueous phase liquid pool geometry in coarse soils with discrete textural interfaces Journal of Contaminant Hydrology,2004,71(1/2/3/4):239-260.
[23]潘玉英.NAPLs地下运移控制因素及监测技术研究[D].青岛:中国海洋大学,2013:52-54.
[24]杨明星.石油有机污染组分在水位波动带中的分异演化机理研究[D].长春:吉林大学,2014:20-22.
[25]LENHARD R J,JOHNSON T G,PARKER J C.Experimental observations of nonaqueous-phase liquid subsurface movement,1993,12(1):79-101.
[26]OOSTROM M,LENHARD R J.Comparison of relative permeabilitysaturation-pressure parametric models for infiltration and redistribution of a light nonaqueous-phase liquid in sandy porous media,1997,21(2):145-157.
[27]熊勇林,朱合华,叶冠林,等.降雨入渗引起非饱和土边坡破坏的水-土-气三相渗流-变形耦合有限元分析[J].岩土力学,2017,38(1):284-290.XIONG Yonglin,ZHU Hehua,YE Guanlin,et al.Analysis of failure of unsaturated soil slope due to rainfall based on soil-water-air seepage-deformation coupling FEM[J].Rock and Soil Mechanics,2017,38(1):284-290.
[28]刘汉乐,周启友,李国山.基于改进多谱图象分析方法的LNAPL分布特性研究[J].工程勘察,2006(9):28-32.
[29]刘汉乐,张晨富,刘宝臣,等.轻非水相液体在不同粒径多孔介质中的运移与分布特性[J].水文地质工程地质,2014,41(2):105-110.LIU Hanle,ZHANG Chenfu,LIU Baochen,et al.Experimental investigation of migration and distribution characteristics of LNAPLcontaminants in porous media of different particle sizes[J].Hydrogeology&Engineering Geology,2014,41(2):105-110.
[2]曹云者,施烈焰,李丽和,等.石油烃污染场地环境风险评价与风险管理[J].生态毒理学报,2007,2(3):265-272.CAO Yunzhe,SHI Lieyan,LI Lihe,et al.Petroleum hydrocarbonscontaminated sites and related risk-based management strategy[J].Asian Journal of Ecotoxicoloy,2007,2(3):265-272.
[3]ATEKWANA E A,ATEKWANA E A.Geophysical signature of microbial activity at hydrocarbon contaminated sites:a review[J].Surveys in Geophysics,2010,31(2):247-283.
[4]王振霞.原油在土壤中的迁移及释放模拟研究[D].青岛:青岛理工大学,2010:5-7.
[5]杨明星,冶雪艳,杨悦锁,等.石油有机组分在包气带水土中残留和迁移差异[J].化工学报,2013,64(11):4231-4239.YANG Mingxing,YE Xueyan,YANG Yuesuo,et al.Residual and migration diversities of petroleum hydrocarbons in vadose zone[J].CIESC Journal,2013,64(11):4231-4239.
[6]VAN GENUCHTEN M T.A Closed-form equation for predicting the hydraulic conductivity of unsaturated soils[J].Soil Science Society of America Journal,1980,44(5):892-898.
[7]LARI S K,DAVIS G B,JOHNSTON C D.Incorporating hysteresis in a multi-phase multi-component NAPL modelling framework:a multi-component LNAPL gasoline example[J].Advances in Water Resources,2016,96(10):190-201.
[8]KUMAR G S.Mathematical modelling on transport of petroleum hydrocarbons in saturated fractured rocks[J].Sadhana,2014,39(5):1119-1139.
[9]NAMBI I M,RAJASEKHAR B,LOGANATHAN V,et al.An assessment of subsurface contamination of an urban coastal aquifer due to oil spill[J].Environmental Monitoring and Assessment,2017,189(4):148.
[10]章艳红,叶淑君,吴吉春.光透法定量两相流中流体饱和度的模型及其应用[J].环境科学,2014,35(6):2120-2128.ZHANG Yanhong,YE Shujun,WU Jichun.Models for quantification of fluid saturation in two-phase flow system by light transmission method and its application[J].Environmental Science,2014,35(6):2120-2128.
[11]李洪,李鑫钢,徐世民,等.饱和区中非水相有机物溶解的实验研究[J].化学工程,2008,36(4):49-52.LI Hong,LI Xingang,XU Shimin,et al.Experimental study of nonaqueous phase liquids dissolution in saturated zone[J].Chemical Engineering(China),2008,36(4):49-52.
[12]李慧颖,杜晓明,伍斌,等.NAPLs污染物指进锋面形态的指间距离预测[J].环境科学研究,2013,26(8):844-850.LI Huiying,DU Xiaoming,WU Bin,et al.Prediction of finger spacing for NAPLs infiltrated in porous media[J].Research of Environmental Sciences,2013,26(8):844-850.
[13]朱振慧,高宗军,张晓海,等.轻质非水相流体(柴油)在多孔介质中的垂向运移[J].环境工程学报,2015,9(4):1842-1848.ZHU Zhenhui,GAO Zongjun,ZHANG Xiaohai,et al.Vertical migration of LNAPLs(diesel)in porous medium[J].Chinese Journal of Environmental Engineering,2015,9(4):1842-1848.
[14]林广宇.地下水位变动带石油烃污染物的迁移转化规律研究[D].长春:吉林大学,2014:55-56.
[15]KECHAVARZI C,SOGA K,ILLANGASEKARE T H.Twodimensional laboratory simulation of LNAPL infiltration and redistribution in the vadose zone[J].Journal of Contaminant Hydrology,2005,76(3):211-233.
[16]WANG W,KUO T,CHEN Y,et al.Effect of precipitation on LNAPL recovery performance:an integration of laboratory and field results[J].Journal of Petroleum Science and Engineering,2014,116(4):1-7.
[17]LENHARD R J,RAYNER J L,DAVIS G B.A practical tool for estimating subsurface LNAPL distributions and transmissivity using current and historical fluid levels in groundwater wells:effects of entrapped and residual LNAPL[J].Journal of Contaminant Hydrology,2017,205(10):1-11.
[18]DATRY T,MALARD F,VITRY L,et al.Solute dynamics in the bed sediments of a stormwater infiltration basin[J].Journal of Hydrology,2003,273(1):217-233.
[19]CLASS H,HELMIG R,NEUWEILER I.Sequential coupling of models for contaminant spreading in the vadose zone[J].Vadose Zone Journal,2008,7(2):721-731.
[20]韩彬,曹磊,郑立,等.综合模拟风化条件下渤海原油中生物标志物及多环芳烃风化规律研究[J].分析测试学报,2010,29(9):871-877.HAN Bin,CAO Lei,ZHENG Li,et al.Weathering disciplinarian of biomarkers and pahs in crude oil from bohai sea under comprehensive simulation[J].Journal of Instrumental Analysis,2010,29(9):871-877.
[21]国家海洋局.GB 17378.5-2007海洋监测规范第5部分:沉积物分析[S].北京:中国标准出版社,2007.
[22]MILLER C D,DURNFORD D S,FOWLER A B.Equilibrium nonaqueous phase liquid pool geometry in coarse soils with discrete textural interfaces Journal of Contaminant Hydrology,2004,71(1/2/3/4):239-260.
[23]潘玉英.NAPLs地下运移控制因素及监测技术研究[D].青岛:中国海洋大学,2013:52-54.
[24]杨明星.石油有机污染组分在水位波动带中的分异演化机理研究[D].长春:吉林大学,2014:20-22.
[25]LENHARD R J,JOHNSON T G,PARKER J C.Experimental observations of nonaqueous-phase liquid subsurface movement,1993,12(1):79-101.
[26]OOSTROM M,LENHARD R J.Comparison of relative permeabilitysaturation-pressure parametric models for infiltration and redistribution of a light nonaqueous-phase liquid in sandy porous media,1997,21(2):145-157.
[27]熊勇林,朱合华,叶冠林,等.降雨入渗引起非饱和土边坡破坏的水-土-气三相渗流-变形耦合有限元分析[J].岩土力学,2017,38(1):284-290.XIONG Yonglin,ZHU Hehua,YE Guanlin,et al.Analysis of failure of unsaturated soil slope due to rainfall based on soil-water-air seepage-deformation coupling FEM[J].Rock and Soil Mechanics,2017,38(1):284-290.
[28]刘汉乐,周启友,李国山.基于改进多谱图象分析方法的LNAPL分布特性研究[J].工程勘察,2006(9):28-32.
[29]刘汉乐,张晨富,刘宝臣,等.轻非水相液体在不同粒径多孔介质中的运移与分布特性[J].水文地质工程地质,2014,41(2):105-110.LIU Hanle,ZHANG Chenfu,LIU Baochen,et al.Experimental investigation of migration and distribution characteristics of LNAPLcontaminants in porous media of different particle sizes[J].Hydrogeology&Engineering Geology,2014,41(2):105-110.