Alafnan Saad
College of Petroleum Engineering and Geosciences, KFUPM, Dhahran 31261, Saudi Arabia.
ACS Omega. 2021 Mar 30;6(14):9549-9558. doi: 10.1021/acsomega.1c00018. eCollection 2021 Apr 13.
Combining hydraulic fracturing with lateral drilling has allowed for economical hydrocarbon production from unconventional formations. Nevertheless, beyond hydraulic fracturing, our understanding of how hydrocarbons are stored and transported from the stimulated volume of a reservoir is still limited. Source rocks consist of organic materials finely dispersed within an inorganic matrix. Despite their small size, these organic pockets are capable of storing significant amounts of hydrocarbon due to their large surface area. The extent of the source rock's storage capacity is determined by several factors, including the natural fracture abundancy, organic material content, type, and level of maturity. The petrophysical properties of organic materials, also known as kerogens, are subject to a high degree of uncertainty. Kerogens are difficult to isolate experimentally, which hinders accurate petrophysical analysis. The objective of this research was to use a molecular modeling approach to explore the petrophysical characteristics of kerogen. Kerogen macromolecules of different types and maturity levels were recreated via a computational platform. Then nanoporous structures representing these kerogens were obtained and characterized. Several elemental parameters, including porosity, density, pore size distribution, and adsorption capacity were closely delineated. The kerogen properties were found to correlate with the kerogen type and thermal maturity level. Kerogen type III showed the highest storage capacity, followed by types II and I, in a descending order. Moreover, in the same type of kerogen, a general trend of increasing storage capacity was observed as the maturity level increased. Methane adsorption capacity was modeled as a function of kerogen porosity. A transition flow regime was found to be the predominant mechanism. Such observations have significant implications for reservoir-scale modeling of unconventional resources.
将水力压裂与水平钻井相结合，使得从非常规地层中经济地开采碳氢化合物成为可能。然而，除了水力压裂之外，我们对于碳氢化合物如何在储层的增产体积中储存和运移的理解仍然有限。源岩由精细分散在无机基质中的有机物质组成。尽管这些有机孔隙体积很小，但由于其巨大的表面积，它们能够储存大量的碳氢化合物。源岩储存能力的大小取决于几个因素，包括天然裂缝的丰富程度、有机物质的含量、类型和成熟度水平。有机物质（即干酪根）的岩石物理性质存在很大的不确定性。干酪根很难通过实验分离出来，这阻碍了准确的岩石物理分析。本研究的目的是使用分子建模方法来探索干酪根的岩石物理特征。通过一个计算平台重建了不同类型和成熟度水平的干酪根大分子。然后获得并表征了代表这些干酪根的纳米多孔结构。详细描述了几个元素参数，包括孔隙率、密度、孔径分布和吸附容量。发现干酪根性质与干酪根类型和热成熟度水平相关。干酪根III型显示出最高的储存能力，其次是II型和I型，呈递减顺序。此外，在同一类型的干酪根中，随着成熟度水平的提高，观察到储存能力总体上有增加的趋势。将甲烷吸附容量建模为干酪根孔隙率的函数。发现过渡流态是主要机制。这些观察结果对非常规资源的储层尺度建模具有重要意义。
