Reactive Transport Modeling of Shale-Fluid Interactions after Imbibition of Fracturing Fluids
Reactive Transport Modeling of Shale-Fluid Interactions after Imbibition of Fracturing Fluids
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DOI：
10.1021/acs.energyfuels.9b04542
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发表时间：
2020-05-21
期刊：
影响因子：
5.3
通讯作者：
Maher, Katharine
中科院分区：
文献类型：
--
作者：
Li, Qingyun;Jew, Adam D.;Maher, Katharine
将水力压裂液（HFF）注入页岩地层用于非常规油/气生产导致页岩基质中的化学反应。我们最近的实验研究确定了页岩基质和HFF之间不同类型反应的深度。在本研究中，我们建立了连续尺度的反应传输模型，以了解这些页岩-HFF系统中的化学反应和水性物质的传输的耦合。用我们以前的实验结果校准模型表明，页岩基质完全中和吸收的酸需要几个小时到几个月的时间，这主要取决于页岩的碳酸盐含量。HFF pH值和孔隙pH值都影响重晶石沉淀的位置，导致独特的重晶石沉淀剖面延伸到富含方解石的Eagle福特页岩中数毫米，但仅延伸到低碳酸盐Marcellus页岩中数十微米。此外，溶解氧和提取的沥青是关键的复制实验观察的Fe（III）（oxyhydr）氧化物形成的页岩基质中的黄铁矿溶解的页岩。本研究中的孔隙度建模结果与我们先前研究中实验测量的渗透率之间的比较表明，在比可观察到的反应区更深的深度处发生的化学反应可能会影响渗透率。我们的模型作为一个基准，有效地模拟水-岩石的相互作用，在类似的系统中，散装岩石样品在间歇反应器中与溶液反应。通过建模确定了重要的反应性运输过程，这允许在给定页岩和HFF组合物的情况下定量预测页岩基质中的页岩-HFF相互作用。
Injection of hydraulic fracturing fluid (HFF) into shale formations for unconventional oil/gas production results in chemical reactions in the shale matrix. Our recent experimental study determined the depths to which different types of reactions between the shale matrix and the HFF extended. In the present study, we built continuum-scale reactive transport models to understand the coupling of chemical reactions and the transport of aqueous species in these shale-HFF systems. Calibration of the model with our previous experimental results reveals that it takes hours to months for the shale matrix to completely neutralize the imbibed acids, depending primarily upon the carbonate content of the shale. Both the HFF pH and pore pH affect the location of barite precipitation, resulting in unique barite precipitation profiles extending millimeters into calcite-rich Eagle Ford shale but only tens of micrometers into low-carbonate Marcellus shale. In addition, dissolved oxygen and extracted bitumen are key to reproducing the experimental observation of Fe(III) (oxyhydr)oxide formation in the shale matrix as a result of pyrite dissolution in the shales. A comparison between the modeling results of porosity in the present study to experimentally measured permeabilities in our previous study suggests that chemical reactions occurring at a greater depth than the observable reaction zone might have impacted permeability. Our model serves as a benchmark for efficiently modeling water-rock interactions in similar systems where bulk rock samples react with a solution in batch reactors. Important reactive transport processes were ascertained via modeling, which allows for quantitative prediction of shale-HFF interactions in shale matrices given the shale and HFF compositions.