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301.
HU Zhikai LI Yi LI Qi DIAO Yujie MA Xin LIU Hejuan FENG Guanhong WANG Fugang YU Qingchun 《《地质学报》英文版》2023,97(3):911-924
Gas breakthrough pressure is a key parameter to evaluate the sealing capacity of caprock, and it also plays important roles in safety and capacity of CO2 geological storage. Based on the published experimental results, we present numerical simulations on CO2 breakthrough pressure in unsaturated low-permeability rock under 9 multiple P-T conditions (which can keep CO2 in gaseous, liquid and supercritical states) and thus, a numerical method which can be used to accurately predict CO2 breakthrough pressure on rock-core scale is proposed. The simulation results show that CO2 breakthrough pressure and breakthrough time are exponential correlated with P-T conditions. Meanwhile, pressure has stronger effects on experimental results than that of temperature. Moreover, we performed sensitivity studies on the pore distribution index λ (0.6, 0.7, 0.8, and 0.9) in van Genuchten-Muale model. Results show that with the increase of λ, CO2 breakthrough pressure and breakthrough time both show decreasing trends. In other words, the larger the value of λ is, the better the permeability of the caprock is, and the worse the CO2 sealing capacity is. The numerical method established in this study can provide an important reference for the prediction of gas breakthrough pressure on rock-core scale and for related numerical studies. 相似文献
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高温高压下岩石弹性波速特征及其在深部地质研究中的意义 总被引:6,自引:2,他引:6
本文收集、整理、研究了70年代以来的高温高压下岩石的Vp,Vs,Vp/Vs,Vp各向异性等实验资料后得出:(1)低压下岩石Vp的急剧变化是由岩石中裂纹与孔隙等引起的;(2)温度升高可增大由岩石组构引起的Vp各向异性的变化率;(3)同种岩石在不同的大地构造环境中具有不同的波速值与变化规律;(4)Vp在高地温区随温度先降低而后升高,其原因是由矿物相变造成的,与地壳中低速带的性质相当。文章最后讨论了实测波速转换为岩石类型时实验研究岩石波速的意义。 相似文献
304.
在实验室中研究了蛇纹岩和角闪岩样品在不同温压条件下的纵、横波速度和Q值.这两种岩样对应的主要组成矿物叶蛇纹石和普通角闪石都具有很强的晶格优选方位(LPO).随着围压的增加,波速和Q值均增大,但是在相互正交的三个方向上(垂直或平行于层理面及线理方向)增大的速度并不相同,这与微裂隙的逐渐闭合密切相关.在600MPa的围压下升高温度直到600℃以上,由于微裂隙的热扩张受到约束,波速和Q值下降幅度很小.观测到的波速和Q值的各向异性具有不同的机理,波速各向异性主要与定向分布的微裂隙和主要矿物的LPO等构造因素有关;高围压下纵波Q值各向异性与速度各向异性正好相反,可能是由于形成层理面的定向排列的平板状矿物晶体沿不同方向边界之间接触程度不同造成的. 相似文献
305.
采用金刚石对顶砧压腔静高压技术,对氧化镍、二氧化钛在0—32GPa压力范围内的电导率进行了测量.结果表明,电导率-压力关系曲线上的一些特征点与同一物质的高压相交点具有一致性. 相似文献
306.
对2001年8月27日至9月1日海南岛受热带风暴"菲特"的各个阶段影响而出现的特大暴雨过程进行了分析,结果发现,这次特大降水是由"菲特"的特征、路径以及海南岛的地形等因素造成了降水分布的时空不均匀。 相似文献
307.
The recovery of drill cores involves changes in pressure and temperature conditions, which inevitably alter the mechanical properties of unlithified sediments. While expansion from unloading after core recovery is well studied, the effects from cooling on standard geotechnical tests are commonly neglected. Along the central portion of the Nankai margin sediments were recovered from high in-situ temperatures of up to 110 °C during IODP Leg 190. So far, the interpretation of the consolidation state of the Lower Shikoku Basin facies (LSB) entering the accretionary Nankai margin is ambiguous. Results from laboratory consolidation tests at room temperature show high pre-consolidation stresses. These were interpreted as hardening caused by cementation, while the field-based porosity vs. depth trend points towards normal consolidation. As an explanation for this discrepancy, the change of the mechanical properties by cooling from in-situ to laboratory conditions is proposed. In this paper, the results of a thermo-mechanical model are compared to published field data. This comparison suggests that the observed hardening is at least partially an artefact from cooling during core recovery, and that the strata may be considered normally consolidated to slightly overconsolidated. The latter can be explained by minor cementation or the influence of secondary consolidation. The results suggest that cooling from high in-situ temperatures may be important for the interpretation of the consolidation state of other sedimentary successions elsewhere. 相似文献
308.
309.
Apparent fracture toughness in Mode I of microcracking materials such as rocks under confining pressure is analyzed based
on a cohesive crack model. In rocks, the apparent fracture toughness for crack propagation varies with the confining pressure.
This study provides analytical solutions for the apparent fracture toughness using a cohesive crack model, which is a model
for the fracture process zone. The problem analyzed in this study is a fluid-driven fracture of a two-dimensional crack with
a cohesive zone under confining pressure. The size of the cohesive zone is assumed to be negligibly small in comparison to
the crack length. The analyses are performed for two types of cohesive stress distribution, namely the constant cohesive stress
(Dugdale model) and the linearly decreasing cohesive stress. Furthermore, the problem for a more general cohesive stress distribution
is analyzed based on the fracture energy concept. The analytical solutions are confirmed by comparing them with the results
of numerical computations performed using the body force method. The analytical solution suggests a substantial increase in
the apparent fracture toughness due to increased confining pressures, even if the size of the fracture process zone is small. 相似文献
310.