Stress Path Analysis of Deep-Sea Sediments Under the Compression-Shear Coupling Load of Crawler Collectors

The mechanical properties of deep-sea sediments during the driving process of crawler collectors are essential factors in the design of mining systems.In this study,a crawler load is divided into a normal compression load and a horizontal shear load.Then,the internal stress state of sedimentary soil is examined through a theoretical calculation and finite element numerical simulation.Finally,the driving of crawlers is simulated by changing the relative spatial position between the load and stress unit,obtaining the stress path of the soil unit.Based on the calculation results,the effect of the horizontal shear load on the soil stress response is analyzed at different depths,and the spatial variation law of the soil stress path is examined.The results demonstrate that the horizontal shear load has a significant effect on the rotation of the principal stress,and the reverse rotation of the principal stress axis becomes obvious with the increase in the burial depth.The stress path curve of the soil is different at various depths.The spatial variation rule of the stress path of the shallow soil is complex,whereas the stress path curve of the deep soil tends to shrink as the depth increases.The stress path of the corresponding depth should be selected according to the actual research purpose and applied to the laboratory test.

Theoretical Analysis and Experimental Verification of Crack Initiation Characteristics of Compression-Shear Plane Crack with Hydraulic Pressure

In this paper, the crack initiation characteristics of compression-shear plane crack with hydraulic pressure were studied by using theoretical analysis and experimental verification methods. The formula derivation process of stress intensity factor of crack tip and open-type crack initiation angle and initiation strength was expounded in detail. Cement mortar specimens prefabricated with open-type crack were made for biaxial compression test. The results show that the mode I stress intensity factor is inversely proportional to the dip angle of pre-exciting crack, water pressure and crack width. The fracture toughness is most easily achieved when the dip angle of pre-exciting crack is 60°. The mode II stress intensity factor is symmetrically distributed with the dip angle and independent of the water pressure and crack width. For open-type crack, the crack initiation angle decreases with the increase of the dip angle of pre-exciting crack, water pressure and crack width;the crack initiation strength is inversely proportional to the water pressure and proportional to the lateral pressure. The research results can provide ideas for the study of crack initiation under the coupling of ground stress and osmotic pressure in tunnel engineering.

基于特征变量扩展的含气饱和度随机森林预测方法

采用数据驱动的方式,提出了一种基于随机森林机器学习算法训练出含气饱和度地震预测方法,并将该方法应用于中国西部复杂天然气藏中,分别对单井资料和二维地震资料进行了含气饱和度预测与分析。研究结果表明:(1)抽取井旁道纵波速度、横波速度和密度3个弹性参数叠前地震反演结果作为基本特征变量样本,引入边界合成少数类过采样技术对基本特征变量样本和对应的含气饱和度样本进行平衡化处理;利用扩展弹性阻抗结合数学变换自动生成一系列的扩展变量;再利用随机森林对特征变量进行含气饱和度预测重要性排名,并优选重要性较高的特征变量进行含气饱和度随机森林训练。(2)该方法大幅减少了特征变量提取和优选的人工工作量,且有效减少了信息冗余以及因含气饱和度样本不平衡导致的训练偏倚问题,有效增强了随机森林算法在含气饱和度地震预测方面的能力。(3)实际单井应用中预测的含气饱和度与测井解释的含气饱和度的相关系数可达0.9855;在二维地震资料应用中,该方法比基于常规未平衡化的11个弹性参数作为随机森林输入预测出的含气饱和度精度更高。

Rheological properties and concentration evolution of thickened tailings under the coupling effect of compression and shear

Cemented paste backfill(CPB)is a key technology for green mining in metal mines,in which tailings thickening comprises the primary link of CPB technology.However,difficult flocculation and substandard concentrations of thickened tailings often occur.The rheological properties and concentration evolution in the thickened tailings remain unclear.Moreover,traditional indoor thickening experiments have yet to quantitatively characterize their rheological properties.An experiment of flocculation condition optimization based on the Box-Behnken design(BBD)was performed in the study,and the two response values were investigated:concentration and the mean weighted chord length(MWCL)of flocs.Thus,optimal flocculation conditions were obtained.In addition,the rheological properties and concentration evolution of different flocculant dosages and ultrafine tailing contents under shear,compression,and compression-shear coupling experimental conditions were tested and compared.The results show that the shear yield stress under compression and compression-shear coupling increases with the growth of compressive yield stress,while the shear yield stress increases slightly under shear.The order of shear yield stress from low to high under different thickening conditions is shear,compression,and compression-shear coupling.Under compression and compression-shear coupling,the concentration first rapidly increases with the growth of compressive yield stress and then slowly increases,while concentration increases slightly under shear.The order of concentration from low to high under different thickening conditions is shear,compression,and compression-shear coupling.Finally,the evolution mechanism of the flocs and drainage channels during the thickening of the thickened tailings under different experimental conditions was revealed.

连云山岩体韧性走滑剪切带变形特征及其动力学

晚侏罗世末‒早白垩世早期中国东部岩石圈经历了从挤压到伸展的构造转变,这一过程反映了古太平洋板片活动方式的变化。连云山岩体位于江南造山带中段,发育E-W向和NE-SW向走滑剪切带。E-W向走滑剪切带(F1)弥散地发育于二云母花岗岩中,而NE-SW向走滑剪切带(F2)以应变集中带形式切过黑云母花岗岩和斑状花岗岩岩株,叠加在F1之上。锆石U-Pb定年结果表明,连云山岩体中剪切变形的黑云母二长花岗岩和斑状花岗岩的侵位年龄分别150±2 Ma和138±5 Ma。从F2剪切带斑状花岗岩中心向边缘,石英C轴组构揭示糜棱岩中石英滑移系从柱面<c>到底面,表明从岩体中心向边缘变形温度从500℃降至约300℃。据此可以确定F1变形时间为150 Ma之后,F2变形时间为斑状花岗岩冷却至中心温度约400~500℃时,接近138 Ma。应力分析揭示两条剪切带发育的最大主应力(σ1)为NEE-SWW向,指示早白垩世早期古太平洋板块向扬子板块低角度俯冲方向为NEE-SWW向,深俯冲板片“回绕”时间略晚于138 Ma。

Influence of strain rate on grain refinement and texture evolution under complex shear stress conditions

The effects of different complex shear stress conditions on grain refinement and texture evolution of Mg-13Gd-4Y-2Zn-0.5Zr alloy were investigated.With increasing strain rate,the average grain size of compression-shear(CS)and compression-torsion(CT)samples are decreased,and the grain size of dynamic recrystallization(DRX)grains is also decreased.This is because that the precipitation number ofβphases is increased,and the hindering effect on grain growth can be significantly enhanced.The DRX fractions of CS and CT samples are decreased with increased strain rate.The low DRX fraction at high strain rate is related to the insufficient time for grains to nucleate.The DRX process can be promoted by the PSN mechanism of second phases,and the grain growth can be restricted by the pinning effect.At the same time,the texture strength is enhanced as the strain rate increased.Besides,the kinking degree of lamellar long-period stacking ordered(LPSO)phases is increased.Under complex shear stress conditions,non-basal slip,especially pyramidal slip,is easily activated and the texture is deflected greatly.Compared with the CS samples,CT samples have smaller average grain size,higher DRX fraction,and lower texture strength for a certain strain rate.This is because that the equivalent stress of the CT sample is larger,the stress triaxiality is smaller,so more serious dislocations are piled up near grain boundaries and second phases.At the same time,since CT sample was sheared with torsion,the dislocation movement path can be called“rotational dislocation accumulation”,and the longer distribution path of the CT sample is generated,so more sub-grains and low-angle grain boundaries(LAGBs)are formed.Compared with the CS sample,more huge-angle grain boundaries(HAGBs)and DRX grains are formed from grain boundary to grain interior,so better grain refinement effect is achieved.

反射波测井的菲涅尔带效应

基于反射波的单井远探测是声波测井发展的一个重要里程碑,可以有效探测距离井数米到数十米的异常反射体如裂缝,极大提升了声波测井的径向探测距离,在碳酸盐岩缝洞储层勘探开发有重要的作用。该文系统考察了有限尺寸裂缝的反射强度与声源频率和反射体宽度的变化特征。模拟结果表明,无论是单极子还是偶极子,反射波的幅度都呈现出菲涅尔带效应。在一定距离内,反射波幅度随裂缝某一方向如宽度增大而增大,当宽带增加一定尺寸后,反射波幅度有一定的程度下降,然后小幅震荡。总之,反射波幅度与反射体尺寸不是简单的正相关,因此,基于反射波能量来评价反射体体积和储量是有条件的。

基于叠前地震纵横波模量直接反演的流体检测方法

流体因子是储层流体识别的重要方法,而叠前地震反演是获得流体因子的有效途径之一.本文从流体因子的构建出发,基于多孔弹性介质岩石物理模型,建立了流体因子与纵横波模量之间的直接关系,避免了流体因子计算所需的密度参数无法准确求取的问题,通过推导基于纵横波模量的Zeoppritz近似方程及弹性阻抗方程,探讨了基于弹性阻抗的纵横波模量直接反演方法,模型与实际应用表明,基于弹性阻抗的纵横波模量直接反演方法合理、可靠,减少了常规方法间接计算纵横波模量带来的累积误差,基于纵横波模量的流体因子计算方法有较好的实际应用效果.

纵横波测井资料在储层评价中的应用

将弹性波基础理论、Gasman理论、Biot理论和实验研究结果相结合 ,探讨了沉积岩地层中速度和弹性模量、弹性模量和孔隙度、剪切模量和孔隙度、速度和孔隙度、孔隙度和Biot系数之间的关系。利用从各种声学测井资料中提取出的P波和S波时差 (或速度 )定量评价地层孔隙度和骨架物质。、辅以泥质指示测井曲线 ,可以计算地层孔隙度、饱和度、岩性等参数。在M .Krief方法的基础上 ,采用优化算法寻求适合于任何岩性地层的孔隙度与Biot系数之间的关系式 ,提高了Biot系数的计算精度。该评价方法有坚实的实验基础和理论基础 。

基于薄层的反射系数谱理论与模型正演

一般的反射系数计算都是以单个界面为基础来进行的 ,而陆相地层主要以薄 (互 )层为主 ,这是一个矛盾。该文在推导出任意入射角入射条件下的多个薄层纵、横波反射系数谱理论基础上 ,进一步简化出了单个薄层垂直入射时的纵波反射系数谱计算公式 ,从而获得了在薄层条件下不同频率成分的纵波反射系数谱数学关系式。由此进一步形成了面向背景的纵波反射模型正演方法。通过采用实际地震子波为输入子波 ,对单个楔状体薄层、薄互层组楔状体地质模型进行了纵波合成记录制作。分析表明 ,其实用性强。不仅提供了一种基于新方法的合成模拟手段 ,更为横向谱比的物理意义分析提供了手段。

海底浅表层沉积物原位声学测量方法探讨

研究透射式和折射式两类海底沉积声学原位测量方法,通过分析10种海底浅表层沉积物声学原位测量仪器的特征,指出不同声学原位测量技术对沉积物声学特性测量结果的影响。比较黄海海底浅表层沉积声学原位测量数据与实验室测量结果的差异,分析原位声学测量数据普遍小于实验室测量数据的原因,指出原位测量的作用和重要性。探讨指出海底浅表层沉积物原位声学测量所需要配合发展的其他物理性质原位测量技术。

随钻声波测井研究进展

论述了随钻声波测井的纵波测量、横波测量及仪器的发展,分析了随钻声波测井面临的难题。随钻纵波测井仪器隔声体是实现随钻纵波测量的关键;利用漏能纵波求取极慢地层的纵波速度的方法也有所发展。对随钻横波测井进行了总结,快地层随钻横波测井除了可以采用单极子测量,还可以采用四极子模式进行测量;慢地层随钻横波测井可以有偶极子或四极子等方式进行测量,存在争议的是慢地层随钻偶极子的横波测量是否可行。对仪器偏心的研究表明从随钻偶极子中提取地层横波是有可能的。随钻声波测井由于偏心的原因无论采用何种模式进行测量都会产生频散。总结了随钻测井噪声的研究现状,表明噪声均为低频噪声,对随钻横波测井有一定影响。

岩石力学参数的计算及应用

岩石力学性质及地层应力在油田勘探开发中有特别重要的指导作用。实践表明,岩石的力学性质及地层应力与地层的声学性质之间有密切的关系。利用从各种声波测井资料提取出的纵、横波速度(或时差)计算岩石的力学参数,并对岩石力学性质在井眼稳定性、砂岩强度分析、水力压裂作业等方面的应用进行了初步探讨。

多极子声波测井的裂缝识别与评价

多极子声波测井在油田应用广泛,对地层裂缝进行评估和分析是其一个重要应用。简要介绍了多极子声波测井在裂缝识别中的国内外研究现状,并简述了多种现有的利用多极子声波测井资料评价裂缝的新方法。以鄂尔多斯盆地X井区实际的多极子声波测井资料处理为例,利用纵横波时差比判断裂缝倾角、井孔模式波声衰减判断裂缝倾角和有效性、斯通利波反射系数确定裂缝位置。利用横波时差各向异性和快慢横波频谱差异估计裂缝发育程度、快横波面方位确定裂缝走向。结合实际电成像测井资料进行了进一步的对比和验证,并对上述方法在裂缝评价中的作用与干扰因素进行了归纳总结。综合应用多种方法进行裂缝识别,可以获取更多的裂缝参数,克服单一方法的部分多解性,从而使基于多极子声波资料的裂缝评价更加准确合理。

疏松砂岩油藏注水开发声波速度的影响因素

由于疏松砂岩声波纵、横波速度的影响因素较多,因此有必要对各影响因素进行定量研究。在模拟地层条件下直接对岩心进行饱和、驱替试验,建立不同的油、水饱和度,并在驱替过程中进行了纵、横波速度的连续测试。结果表明:水驱至含水饱和度极限时,岩心纵波速度平均增加7.4%左右,横波速度基本不变;在水驱过程中,由于岩石骨架发生变化,岩石变得疏松,致使岩心纵波速度降低3.1%左右,因此水驱至含水饱和度极限时,最终的岩心纵波速度只增加4.3%左右;对于注水效果好的稀油油藏,温度及压力对声波速度的影响较弱,但是对于地层能量补充不充分的区块及稠油油藏,温度及压力对声波速度的影响不能忽略。

多分量转换波地震勘探技术

多分量转换波地震勘探既具有纵波勘探深度大、资料采集相对容易和投资少的特点 ,又能反映地下介质的横波速度变化。该技术的这一特点 ,使岩石和油气的直接识别成为可能。同时 ,由于多分量的数据采集可以利用横波分裂产生的快慢横波时差 ,反映裂缝发育的主方向和发育密度 ,使得裂缝油气藏的勘探成为可能。如今 ,二者紧密相连的各向异性理论方法研究 ,已成为国内外地震勘探领域的研究热点之一 ;建立与完善多分量地震资料处理解释系统 ,是这项技术发展的当务之急。

薄互层等效各向异性的实验研究

针对我国一些油田的储集层具有薄互层结构，本文研究了薄互层中弹性波的传播特性。在实验室条件下，选用两类薄互层样品，第一类为铝板和有机玻璃，第二类为铝板和蜡，层间粘合剂选用环氧树脂。经过实验室测量结果证实，当波长λ远大于薄互层中各单一夹层的层厚h（λ／h＞10）时，通过上述第一类样品的纵波呈现明显的各向异性特征；通过上述第二类样品的横波具有明显的各向异性特征。

岩石的纵、横波速度与密度的规律研究

选择了济阳坳陷第三系地层四类不同岩性、237块典型岩心样品,在变温变压条件下进行超声波纵、横波速度及密度的测定,样品的孔隙度范围从2%到27%.根据变温变压测试数据,得出纵横波速度的压力、温度校正公式,将高温高压条件下测量的弹性参数校正到60 MPa条件,再进行密度、Vp和Vs数据分析.分析结果表明:Vp、Vs具有很好的线性相关性,得到新的密度与Vp关系式.同时将Vp、Vs关系融入到Gardner公式中,将Gardner函数推广为ρ=CVpAVsB的函数形式(称为广义Gardner公式),拟合出砂岩的密度、Vp和Vs间的新关系式:ρ=1.575 8V0.p287 9V0s.019 7.文中讨论了该公式在横波速度预测、岩石物理模拟和AVO正反演等的作用,指出这些规律性认识可服务于油气勘探和开发.

利用纵、横波品质因子比值识别含气碳酸盐岩层

利用偶极横波声波成像(Dipole Shear Sonic Imager,DSI)测井资料计算了纵、横波衰减和纵、横波品质因子QP和QS.对纵、横波在碳酸盐岩含气层和非含气层中的衰减特征研究表明,碳酸盐岩含气层中的纵波衰减比非含气层中的纵波衰减强;横波衰减和横波品质因子在碳酸盐岩含气层和非含气层中的变化不大。根据DSI测井资料计算出的纵、横波衰减和纵、横波品质因子在碳酸盐岩含气层和非含气层中的这些差异,给出了一种利用纵、横波品质因子比值QP/QS识别碳酸盐岩含气层的方法。

气层和异常高压带地震特征的超声波实验研究

利用超声波观测方法在实验室内分别研究了砂岩露头岩样在不同孔隙流体压力和含气 (水 )饱和度条件下所引起的地震响应 ,由实验观测得出如下结论 :①纵横波速度、品质因子、主频均随孔隙压力从低到高而逐渐减小。②随含水饱和度的增加或含气饱和度的减小 ,纵波速度在低含水饱和度基本保持不变 ,而当含水饱和度达到一定程度时 ,纵波速度明显增大 ;而随含水饱和度的增加 ,横波速度略有降低或基本保持不变 ;③砂岩部分气水饱和时 ,纵波品质因子和主频最小 ;而横波品质因子在低含水饱和度时 ,随含水饱和度的增加 ,横波品质因子和主频降低较快 ,当含水饱和度达到一定值后 ,横波品质因子和主频基本保持不变。这些认识可以作为利用地震方法来检测异常高压带和含气层的标志 ;同时也指明了用地面地震资料来检测异常高压带和含气层时应该使用的参数和方法。