Characterization and Evolution of Nanoporosity in Superdeeply Buried Shales: A Case Study of the Longmaxi and Qiongzhusi Shales from MS Well #1, North Sichuan Basin, China
Characterization and Evolution of Nanoporosity in Superdeeply Buried Shales: A Case Study of the Longmaxi and Qiongzhusi Shales from MS Well #1, North Sichuan Basin, China
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超深埋页岩纳米孔隙特征及演化——以川北MS 1井龙马溪、筇竹寺页岩为例
DOI：
10.1021/acs.energyfuels.7b02932
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发表时间：
2018-01-01
期刊：
影响因子：
5.3
通讯作者：
Sun, Wei
中科院分区：
文献类型：
--
作者：
Jiao, Kun;Ye, Yuehao;Sun, Wei
来自超深埋藏的龙马溪页岩（从地面以下6604-6920 m处回收的岩心）、五峰页岩（6920-6926 m）和琼竹寺页岩（7960-8044 m）的页岩样品的纳米孔特征是从中国四川省MS 1号井中研究的，该井于2016年3月完工，是亚洲最深的陆上钻井。为了更好地了解埋藏深度对页岩孔隙系统的影响，并帮助研究纳米孔隙特征，通过FESEM和N-2气体吸附分析样品。从0到5000米的深度范围内恢复的四川盆地页岩样品被选为对照组。结果表明，在所有32个超深埋页岩样品从三个地层中的纳米孔特征相似。超深埋藏页岩的孔隙类型以有机质孔隙和粒间孔隙为主，沿着少量粒内孔隙。主要的孔隙形态是狭缝状。低压N-2吸附分析表明，所有样品的等温线都是IV型与H3滞后模式。淬灭固体密度泛函理论（QSDFT）孔径分布主要在4-16 nm范围内，BET表面积在8.63 - 16.13 m2/g之间。与非超深埋藏页岩相比，MS井1中的超深埋藏页岩具有更分散的孔径分布、更低的孔隙体积和孔隙表面积以及更高的中孔体积和中孔表面积。因此，超深埋页岩的中孔/孔隙体积和中孔/孔隙表面积比非超深埋页岩高几个数量级。与埋藏深度相关的压实作用可压缩孔隙，使孔隙尺寸减小，孔隙形状由圆形或椭圆形变为狭缝形。由于其相对较小的孔隙尺寸，微孔在超深埋藏阶段最容易被破坏。
The nanopore characteristics of shale samples from the superdeeply buried Longmaxi Shale (drillcore recovered from 6604-6920 m below ground level), Wufeng Shale (6920-6926 m), and Qiongzhusi Shale (7960-8044 m) were studied from MS Well #1, Sichuan Province, China, which was completed in March 2016 and is the deepest onshore well yet drilled in Asia. To gain a better understanding, of the influence of burial depth on the pore system of shales and to aid in the study of nanopore characteristics, the samples were analyzed by FESEM and N-2 gas adsorption. Samples of Sichuan Basin shales recovered from depths ranging from 0 to 5000 m were selected as a control group. The results show similar nanopore characteristics in all 32 superdeeply buried shale samples from the three formations. The dominant pore types in the superdeeply buried shales are organic matter pores and interparticle pores, along with minor intraparticle pores. The dominant pore morphology is slit-like in shape. Low-pressure N-2 adsorption analysis shows that the isotherms of all samples are type IV with an H3 hysteresis pattern. The quenched solid density functional theory (QSDFT) pore size distribution is dominantly in the range of 4-16 nm, and the BET surface area ranges between 8.63 and 16.13 m(2)/g. In comparison with nonsuperdeeply buried shales, superdeeply buried shales in MS Well #1 have a more dispersed pore-size distribution, lower micropore volume and micropore surface area, and higher mesopore volume and mesopore surface area. Thus, the mesopore/micropore volume and mesopore/micropore surface area ratios of the superdeeply buried shales are several orders of magnitude higher than those of the nonsuperdeeply buried shales. Compaction related to burial depth may compress the pores to reduce the pore sizes and change the pore shapes from round or elliptical-shaped to slit-shaped. Given their relatively small pore sizes, micropores are most easily destroyed during the superdeep burial stage.