CO2 地质封存是减少大气中CO2 排放，降低温室效应的重要途径，CO2注入含水地层中时，CO2-水-岩反应可能引起岩石矿物的侵蚀，对CO2地质封存安全性产生显著影响。在室内实验中，通过表征岩石表面的形貌特征可以有效地评估 CO2-水-岩反应程度，为 CO2 地质封存的安全性评估提供科学依据。通过三维点云计算可以精确量化地表征CO2-水-岩反应程度，这种方法首先运用三维激光扫描技术，构建岩石表面的三维模型，确定CO2-水处理前岩石表面三维模型的基准面，并基于处理前的均方根粗糙度确定处理后岩石表面三维模型的基准面。基于三维模型点云信息，提出了两种不同的体积计算新方法，并通过对规则模型体积的计算比较了两种计算方法的准确性与适用性，可根据实际情况选择两种计算方法量化表征CO2-水处理前后岩石表面的侵蚀体积。最后，以陕西省咸阳市某煤矿煤样为例，开展了 CO2-水-岩反应模拟试验，验证了计算的可行性。试验结果表明:该文提出的侵蚀体积计算方法可有效地量化表征 CO2-水-岩反应程度，CO2-水处理后岩石表面不同区域的侵蚀差异性明显，岩石表面的侵蚀体积与均方根粗糙度之间存在显著的正比关系，随着均方根粗糙度的增大，侵蚀体积也相应上升。
Quantitative characterization method of CO2-water-rock reaction degree based on three-dimensional point cloud computing
[Objective]Fossil fuels such as coal,oil,and natural gas have been pivotal in shaping modern society,yet their use has resulted in significant emissions of greenhouse gases like carbon dioxide CO2.In pursuit of sustainable development,China has adopted strategies aimed at achieving carbon peak and carbon neutrality,prioritizing carbon reduction and energy transformation.CO2 storage is an effective strategy for mitigating the greenhouse effect,a practice that has gained global traction.The CO2-water-rock reaction plays a crucial role in CO2 geological sequestration,with the rock surface being a critical site for this reaction.Understanding the topography of rock surfaces is essential for assessing the degree of CO2-water-rock reactions and ensuring the safety of CO2 geological sequestration.Methods for characterizing rock surface topography are mainly classified into two categories.The first relies on scanning electron microscopy observations and energy-dispersive X-ray spectroscopy analysis,which,despite offering detailed surface topography,is limited by its inability to capture depth information adequately.The second category encompasses quantitative characterization methods based on surface roughness and fractal dimension derived from statistical principles.While these methods provide valuable quantitative parameters,their physical significance is not intuitively clear,nor do they directly correlate with rock erosion.[Methods]This paper introduces a new quantitative method for assessing the degree of CO2-water-rock reactions through a method based on three-dimensional point cloud computing.This method aims to quantify the reaction degree on the rock surface more intuitively by measuring erosion volume.Utilizing three-dimensional laser scanning technology,point cloud data is acquired to construct a three-dimensional model of the rock surface.This model helps define the depression volume and determine the base level of the rock surface before and after CO2-water treatment,using the root-mean-square roughness as a reference.In this paper,we propose two new methods for volume calculation,namely the concave method and the convex method.By applying these methods to calculate the volume of a regular model,their accuracy and applicability are compared.This comparison allows for the quantitative characterization of the erosion volume on the rock surface before and after CO2-water treatment.Depending on the specific conditions,either calculation method can be selected to quantify the erosion volume of the rock surface before and after CO2-water treatment.Finally,the paper uses coal samples from the Zhengtong Coal Mine,Changwu County,Xianyang City,Shaanxi Province,to validate the feasibility of the proposed erosion volume calculation method.[Results and Conclusions]These tests sought to simulate the CO2-water-rock reactions and assess the effectiveness of the method in quantifying and characterizing the reaction degree.After CO2-water treatment,a clear distinction in erosion across different areas on the rock surface was observed.Furthermore,the results revealed a significant proportional relationship between the erosion volume on the rock surface and the root-mean-square roughness.
three-dimensional point cloudCO2-water-rockdatum planeroot-mean-square roughnessreaction degree
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