Pore structure characterization of North American shale gas reservoirs using USANS/SANS, gas adsorption, and mercury intrusion
Pore structure characterization of North American shale gas reservoirs using USANS/SANS, gas adsorption, and mercury intrusion
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DOI：
10.1016/j.fuel.2012.06.119
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发表时间：
2013-01-01
期刊：
影响因子：
7.4
通讯作者：
Blach, T. P.
中科院分区：
文献类型：
--
作者：
Clarkson, C. R.;Solano, N.;Blach, T. P.
对一套北美页岩储层样品进行了小角和超小角中子散射(SANS和USANS)、低压吸附(N-2和CO2)和高压汞侵入测量，首次比较了所有这些表征页岩复杂孔隙结构的技术。这些技术被用来洞察孔隙结构的性质，包括孔隙几何形状、孔隙大小分布以及可访问和不可访问的孔隙度。用于分析的储集层样品取自目前活跃的页岩气，包括Barnett、Marcellus、Hayensville、Eagle Ford、Woodford、Muskwa和Duvernay页岩。低压吸附显示，样品套的BET表面积和孔隙体积存在很大差异，这与样品组成的变化一致。结合CO2和N-2吸附数据，可以创建微、中、大孔隙率的孔径分布，最高可达1000埃。孔径分布呈单峰或多峰分布。一些样品的吸附得到的孔径分布与汞侵入数据不一致，这可能是由于高压侵入过程中的颗粒压缩，以及汞侵入产生关于孔喉而不是孔体分布的信息的事实。SANS/USANS散射数据表明，在很大范围内的孔隙大小都是分形几何(幂定律散射)，并提供了证据，表明一些样品在较低的中孔-微孔范围内发生了纳米尺度的空间有序化，这可能与粘土矿物的层间距有关。SANS/USANS孔半径分布被转换为孔体积分布，以便与吸附数据直接比较。对于两种方法之间的重叠区域，吻合程度较好。采用加压重水甲烷流体对比匹配法测定了Barnett页岩样品在孔径(半径)为5 nm~10µm范围内的可利用孔隙度。结果表明，可达孔隙率与孔隙大小有关。(C)2012爱思唯尔有限公司。保留所有权利。
Small-angle and ultra-small-angle neutron scattering (SANS and USANS), low-pressure adsorption (N-2 and CO2), and high-pressure mercury intrusion measurements were performed on a suite of North American shale reservoir samples providing the first ever comparison of all these techniques for characterizing the complex pore structure of shales. The techniques were used to gain insight into the nature of the pore structure including pore geometry, pore size distribution and accessible versus inaccessible porosity. Reservoir samples for analysis were taken from currently-active shale gas plays including the Barnett, Marcellus, Haynesville, Eagle Ford, Woodford, Muskwa, and Duvernay shales.Low-pressure adsorption revealed strong differences in BET surface area and pore volumes for the sample suite, consistent with variability in composition of the samples. The combination of CO2 and N-2 adsorption data allowed pore size distributions to be created for micro-meso-macroporosity up to a limit of similar to 1000 angstrom. Pore size distributions are either uni- or multi-modal. The adsorption-derived pore size distributions for some samples are inconsistent with mercury intrusion data, likely owing to a combination of grain compression during high-pressure intrusion, and the fact that mercury intrusion yields information about pore throat rather than pore body distributions.SANS/USANS scattering data indicate a fractal geometry (power-law scattering) for a wide range of pore sizes and provide evidence that nanometer-scale spatial ordering occurs in lower mesopore-micropore range for some samples, which may be associated with inter-layer spacing in clay minerals. SANS/USANS pore radius distributions were converted to pore volume distributions for direct comparison with adsorption data. For the overlap region between the two methods, the agreement is quite good. Accessible porosity in the pore size (radius) range 5 nm-10 mu m was determined for a Barnett shale sample using the contrast matching method with pressurized deuterated methane fluid. The results demonstrate that accessible porosity is pore-size dependent. (C) 2012 Elsevier Ltd. All rights reserved.