不同沉积年代泥岩卸荷力学特性试验研究

发布时间：2018-04-18 10:36

本文选题：泥岩 + 地质年代　；参考：《岩土力学》2017年03期

【摘要】：鄂西渝东地区蕴藏着丰富的油气资源,纵向主要分布有侏罗系和志留系两套泥岩盖层,区域经历的抬升剥蚀过程会导致盖层破裂,影响油气保存。选取沉积于侏罗系沙溪庙组、桐竹园组以及志留系龙马溪组的3个典型区块泥岩,开展10~50MPa 5种围压下的三轴卸荷力学试验,探索卸荷对泥岩力学特性影响。研究表明:随卸荷围压增大,3类泥岩的卸荷效应均增强,侏罗系泥岩体现在卸荷变形增大,志留系泥岩主要体现在沿卸荷方向的侧向膨胀;对比常规三轴压缩试验中岩石破裂时的应力状态,卸荷得到的泥岩强度均上升,内摩擦角更大,泥岩侧压破裂系数呈负指数分布,随围压增大而减小,并且沉积时间短浅的泥岩在抬升剥蚀过程中更容易产生破坏;岩石破裂形态由岩石组构与应力环境共同决定,沙溪庙组泥岩的裂纹形态为单一剪切断面破坏,并且断口平缓,而桐竹园组泥岩与龙马溪组泥岩则随围压升高,由单一剪切断面向共轭剪切破坏过渡,其中桐竹园组泥岩断口平滑,龙马溪组泥岩断口则呈现锯齿状。
[Abstract]:There are abundant oil and gas resources in the area of western Hubei and eastern Chongqing. There are mainly Jurassic and Silurian mudstone caprocks in longitudinally. The uplift and denudation process of the region will lead to the rupture of the caprock and affect the preservation of oil and gas.Three typical blocks of mudstone deposited in Jurassic Shaximiao formation, Tongzhuyuan formation and Silurian Longmaxi formation were selected to carry out triaxial unloading mechanical tests under five confining pressures of 10~50MPa to explore the effect of unloading on the mechanical properties of mudstone.The results show that the unloading effect of three types of mudstone increases with the increase of confining pressure, Jurassic mudstone increases in unloading deformation, and Silurian mudstone is mainly in lateral expansion along unloading direction.Compared with the stress state of rock fracture in conventional triaxial compression test, the strength of mudstone obtained by unloading is higher, the angle of internal friction is larger, and the coefficient of lateral compression fracture of mudstone is a negative exponential distribution, which decreases with the increase of confining pressure.The rock fracture morphology is determined by the rock fabric and stress environment, the crack form of the mudstone in Shaximiao formation is single shear section failure, and the fracture surface is gentle.The mudstone of Tongzhuyuan formation and Longmaxi formation are changed from single shear section to conjugate shear failure with the increase of confining pressure. The mudstone fracture surface of Tongzhuyuan formation is smooth and the mudstone fracture surface of Longmaxi formation is serrated.
【作者单位】：重庆大学煤矿灾害动力学与控制国家重点试验室;中国石油化工股份有限公司石油勘探开发研究院;中国科学院武汉岩土力学研究所岩土力学与工程国家重点试验室;西南科技大学;
【基金】：重庆大学国家重点试验室开放基金(No.2011DA105287-FW201404)~~
【分类号】：TE311

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