Chemomechanical evolution of pore space in carbonate microstructures upon dissolution: Linking pore geometry to bulk elasticity
Chemomechanical evolution of pore space in carbonate microstructures upon dissolution: Linking pore geometry to bulk elasticity
复制标题
溶解时碳酸盐微观结构中孔隙空间的化学机械演化：将孔隙几何形状与体弹性联系起来
DOI：
10.1002/2015jb012087
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发表时间：
2015
期刊：
影响因子：
--
通讯作者：
T. Vanorio
中科院分区：
文献类型：
--
作者：
C. Arson;T. Vanorio
当今在各种地球物理应用中面临的挑战之一是需要了解由于时变化学力学过程而导致的弹性性质的变化。这项工作的目的是模拟碳酸盐岩的弹性性能作为孔隙几何形状的变化时发生的固体基质溶解二氧化碳的功能。我们比较了两种碳酸盐微观结构：多孔泥晶灰岩（“泥岩”）和颗粒支撑碳酸盐（“堆积石”）。我们制定了一个数学模型，区分微孔和大孔刚度变化的影响。我们使用的措施，机械和化学孔隙度的变化记录在注射测试计算弹性模量，并比较它们从波速测量获得的模量。在泥岩中，实验和数值计算结果表明，体积模量的变化小于5%。弹性模量的演化受大孔隙扩大的控制。在碎石中，模型预测低估了总孔隙率的弹性模量变化10%至80%。总孔隙度变化比化学孔隙度变化小60%至75%，这表明由于溶解引起的孔隙膨胀被由于压实引起的孔隙收缩所抵消。碎石的弹性特性受颗粒滑动的控制。本文提出的方法可以推广到岩石中其他化学力学过程的研究，如位错，滑移，扩散传质，重结晶和沉淀。
One of the challenges faced today in a variety of geophysical applications is the need to understand the changes of elastic properties due to time‐variant chemomechanical processes. The objective of this work is to model carbonate rock elastic properties as functions of pore geometry changes that occur when the solid matrix is dissolved by carbon dioxide. We compared two carbonate microstructures: porous micrite (“mudstone”) and grain‐supported carbonate (“packstone”). We formulated a mathematical model that distinguishes the effects of microporosity and macroporosity on stiffness changes. We used measures of mechanical and chemical porosity changes recorded during injection tests to compute elastic moduli and compare them to moduli obtained from wave velocity measurements. In mudstones, both experimental and numerical results indicate that bulk moduli change by less than 5%. The evolution of elastic moduli is controlled by macropore enlargement. In packstones, model predictions underestimate changes of elastic moduli with total porosity by 10% to 80%. The total porosity variation is 60% to 75% smaller than the chemical porosity variation, which indicates that pore expansion due to dissolution is counterbalanced by pore shrinkage due to compaction. Packstone elastic properties are controlled by grain sliding. The methodology presented in this paper can be generalized to other chemomechanical processes studied in rocks, such as dislocations, glide, diffusive mass transfer, recrystallization, and precipitation.