富油煤原位热解产生的油、气在高温作用下会通过煤层顶板的裂隙带向覆岩层迁移富集，给地下环境造成潜在污染风险。为了了解富油煤地下热解过程中典型污染物的释放与分布特征，以陕北侏罗纪煤田神府矿区典型富油煤为研究对象，基于研究区地层结构与岩性资料，采用自主研发的富油煤原位热解相似模拟实验装置，研究富油煤热解产物的组成，及不同温度下煤焦油中酚油、萘油、洗油、蒽油和沥青等典型污染物的时空分布特征。

结果表明：不同热解温度下，典型污染物在覆岩中的分布随时间增加均呈现先上升后下降的趋势，且各组分含量与富集层位差异较大。热解温度为450 ℃和650 ℃下，不同覆岩层中污染物含量大小排序为沥青>蒽油>萘油>洗油>酚油。在 450 ℃时，由于温度较低对覆岩层影响相对较小，所以各组分主要富集在中粒砂岩层。随着温度不断升高，覆岩层产生裂隙，导致650 ℃时轻质组分富集在距煤层较远的泥岩层，重质组分由于密度大且黏性强，迁移能力较差，所以其主要富集区域为泥质粉砂岩层。温度是影响覆岩中典型污染物时空分布特征的主要因素，升高温度会增加污染物的迁移范围，并且酚油、萘油和洗油含量的占比随之逐渐增大，蒽油和沥青含量的占比随之逐渐减小。研究结果为富油煤原位热解地下污染管控提供理论依据。

Under high temperatures, oil and gas produced from the in situ pyrolysis of tar-rich coals will migrate toward and accumulate in the overburden strata after passing through the fracture zones on the coal seam roof, causing potential contamination risks for the underground environment. To understand the release and distribution characteristics of typical contaminants generated from the underground pyrolysis of tar-rich coals, this study investigated the typical tar-rich coals from the Shenfu mining area of the Jurassic coalfield in northern Shaanxi Province. Based on data on the stratigraphic structures and lithology and using the self-developed equipment for similarity simulation experiments on the in-situ pyrolysis of tar-rich coals, this study examined the composition of the pyrolysis products of tar-rich coals, along with the spatiotemporal distributions of typical contaminants like carbolic oil, naphthalene oil, washing oil, anthracene oil, and asphalt in coal tar under different temperatures.

The results indicate that the contents of typical contaminants in the overburden strata increased first and then decreased with time under different pyrolysis temperatures, with various components differing greatly in content and enrichment horizon. Under pyrolysis temperatures of 450 ℃ and 650 ℃, the contaminant contents in different overburden strata decreased in the order of asphalt, anthracene oil, naphthalene oil, washing oil, and carbolic oil. At 450 ℃, various components were primarily enriched in the medium-grained sandstone layer due to the relatively minor impacts of the low temperature on the overburden strata. With an increase in temperature, fractures occurred in the overburden strata. Consequently, light components were enriched in the mudstone layer far away from the coal seam at 650 ℃. In contrast, heavy components, featuring high densities and viscosities but a low migration ability, were predominantly distributed in the argillaceous siltstone layers. Temperature was identified as a primary factor influencing the spatiotemporal distributions of typical contaminants in the overburden strata. Specifically, an increase in the temperature would extend the migration range of contaminants. Furthermore, the proportions of carbolic oil, naphthalene oil, and washing oil progressively increased, while those of anthracene oil and asphalt gradually decreased as the temperature rose. The results of this study will provide a theoretical basis for the control of the underground contamination caused by the in-situ pyrolysis of tar-rich coals.