渝西地区五峰组—龙马溪组深层页岩储层力学脆性的非均质性特征——以Z-3井为例

为了研究储层力学脆性对层段优选的作用,针对页岩储层力学脆性的非均质性特征,以渝西地区Z-3井五峰组—龙马溪组页岩储层为例,通过手标本观测、岩石薄片观测、扫描电镜观测、X射线衍射、单轴抗压实验、三轴抗压实验、巴西抗拉强度等储层分析手段,测试评价储层的力学脆性特征,并表征其层段非均质性。结果表明,深层页岩储层物性受特殊储层成岩作用影响非均质性相对减弱,其评价需要不同于中浅部储层的新指标体系。综合峰前、峰后曲线特征的脆性指数和脆性矿物比例参数两种评价方式,可得五峰组—龙马溪组底部是相对优质的力学脆性层段;受沉积环境、矿物组分与沉积分异、差异成岩作用等因素的控制,五峰组—龙马溪组页岩储层具有力学脆性非均质性,主要体现在储层的矿物组分比例、微观沉积特征及力学脆性特征具有横向稳定的层段性差异,可以作为页岩气压裂层段优选与勘探开发的科学依据。

Ge_xSe_(90-x)Sb_(10)硫系玻璃的热力学特性和动力学脆性研究

采用DSC对熔融-淬冷法制备的GexSe90-Sb10（F20，23，25，30）玻璃及其晶体的性质进行了研究，获得了GexSe90-Sb10玻璃在不同加热速率下的玻璃化转变温度正以及玻璃与晶体的比热容和熵随温度的变化关系，在此基础上确定出了GexSe90-Sb10的动力学理想玻璃化转变温度L，热力学理想玻璃转变温度TK（Kauzmann温度）及动力学脆性参数m．结果表明，GexSe90-Sb10的Ts，玻璃与晶体的比热容和熵均随着升温速率的增加而增大．Tg和T0随Ge含量的增加呈现先增大后减小的变化规律，冗随Ge含量的增加呈现线性增大的规律．GexSe90-Sb10玻璃的m，Tg/Tk,Tg/Tm和Tg/T0分别为20．7～23．2，1．183～1．352，0．678～0．742和1．006～1．019．GexSe90-Sb10玻璃的m均小于30，Tg/Tk均大于1．1，说明其为典型的“强”熔体；Tg/Tm均大于2／3，说明其玻璃化形成能力比较强。

深层页岩储层脆性评价及综合脆性指标评价优化路径研究——以Z-3井五峰组—龙马溪组为例

页岩的岩石脆性是页岩油气藏可压裂性的重要影响因素,也对页岩油气工程有指导价值。对国内外的脆性评价方法进行归类和研究分析,以Z-3井五峰组—龙马溪组为例,通过单轴抗压实验、三轴抗压试验和巴西劈裂实验等岩石力学实验手段,获取计算脆性指标的必要数据,从而进行脆性指标的检验和对比评价。研究结果显示,矿物组分法忽略了成岩作用、岩石受力条件和地区等因素;力学强度参数法脆性指标的数值敏感度不好,并且出现与实际情况相反的现象;弹性参数法参数修改的工作量大,线性加权权值的选取未加以说明;应力应变曲线法存在特殊情况使得指标失效,而且存在较为严重的系统误差和人为误差等问题。综合当前研究方法的局限性,提出基于组合赋权法构建综合脆性指标的思路,为工程技术人员提供参考。

Na_2O-TeO_2系统玻璃形成液体脆性的研究

通过测量Na2 O -TeO2 系统玻璃转化区的热容曲线 ,对该系统不同成分玻璃形成液体的热力学和动力学脆性进行研究。结果表明 :该系统玻璃形成液体从热力学和动力学综合看脆性程度介于强弱之间 ,为中性偏脆性。随着氧化钠含量的升高 ,玻璃形成液体的脆性增强。用Kissinger方程和Ritland -Bartanev方程 ,得到的在玻璃转变区的结构松弛激活能十分接近。

页岩层系不同岩矿组合试样渗透率变化规律差异及其机理分析

页岩地层垂向岩矿组合变化大,页岩气开采需要对储层进行大规模人工水力压裂改造。笔者等基于样品的全岩X-射线衍射分析,通过对不同岩矿组合的3块页岩试样进行流—固耦合物理模拟实验,获得了3点认识,反映了不同岩矿成分的页岩在不同条件微裂缝与渗透率的变化特征,以及碳酸盐矿物含量高时的影响。这一实验对于研究页岩储层在压裂过程中的变化具有探索性,对于页岩气生产具有重要的参考意义。

页岩储层成岩作用及其对储层脆性的影响——以渝西地区五峰组—龙马溪组深层页岩为例

页岩粒度细小、岩石致密、微观非均质性显著,在成岩作用改造下发育形成页岩气储层,成岩作用的研究可以为优质页岩储层发育机理提供依据。以渝西地区綦江观音桥剖面、南川泉浅1井、南川三泉剖面、大足Z-203井等代表性剖面、钻孔为例,通过X射线衍射、氩离子抛光—场发射扫描电镜、能谱、岩石薄片/光片显微观察、有机地球化学测试、力学特征测试等手段,对储层成岩作用及其对储层力学脆性的影响展开系统研究。结果表明,研究区五峰组—龙马溪组页岩物质组分、岩石结构、力学性质存在层段性差异,成岩作用阶段介于晚成岩作用阶段至极低级变质作用阶段之间;储层主要成岩作用类型可以划分为压实作用等物理性成岩作用、矿物溶蚀作用等矿物相关化学性成岩作用和有机质生烃作用等有机质相关化学性成岩作用三类。研究区五峰组—龙马溪组底部存在部分脆性矿物高于80%的超高脆性矿物含量层段,碳质—硅质富层理页岩在特殊储层成岩作用的影响下形成大量自生微晶石英,构成以微晶石英+赋孔有机质为主的显微物相组合,兼具良好的力学脆性与储集能力,而其他层段缺乏持续演化不断形成微晶石英的物质基础。储层成岩作用发生的物质基础、岩石结构、类型、作用强度在层段间的差异,是储层脆性矿物与力学性质差异的关键影响因素,应纳入储层评价与优质储层机理研究的关注范畴。

深层海相页岩脆性特征分析与表征

针对中国南方深层海相页岩气开发尚未突破的现实,以四川盆地五峰组—龙马溪组页岩为研究对象,聚焦深层海相页岩的脆性表征,建立了基于全应力—应变曲线的脆性定量评价指标,以峰值应变和峰后坡降陡度分别表示页岩发生脆性破坏的难易程度和充分程度。在此基础上,通过对硅质页岩、钙质硅质页岩、钙质页岩和黏土质硅质页岩开展高围压三轴压缩岩石力学实验,明确了围压对页岩脆性的影响,建立了适用于研究区深层海相页岩的脆性评价方法,开展了深浅层页岩脆性对比。结果表明,低围压时,围压主要表现为对页岩抗压强度的强化,脆性随围压增加而增强,高围压时,围压则主要表现为对裂缝产生与扩展的抑制,脆性随围压增加而减弱;以弹性参数为岩性指示因子,以断裂韧性为围压指示因子,建立了力学脆性指数,可作为矿物法和弹性参数法的补充,有效应用于3500m以深页岩储集层的脆性评价;硅质页岩和钙质硅质页岩在4500~5000m仍具有优质储集层的潜力,但是深层海相页岩脆性的弱化使得优质储集层厚度减小。

近场动力学与有限单元法的混合模型与隐式求解格式

利用近场动力学方法(PD)在模拟不连续变形问题的独特优势和有限单元法(FEM)的计算效率,提出近场动力学与有限单元法混合建模的方法,并用于求解断裂力学问题.裂纹出现的区域采用改进的近场动力学微观弹脆性(PMB)模型进行离散,其他区域采用有限元离散,通过杆单元连接不同的子区域.在隐式求解体系下实现了两种方法的混合建模,该模型在求解静力学问题时无需引入阻尼项,有效提高了计算效率和计算精度.通过模拟计算简支梁的弹性变形和三点弯曲梁I型裂纹的扩展过程,与理论解吻合良好,验证了提出的混合模型和求解方法的准确性和有效性.

基于3D-ILC含60°平行双内裂纹脆性巴西圆盘断裂特性

裂纹间的相互作用是断裂力学的重要研究内容,但针对3维内裂纹的扩展规律及相互作用的研究较少。基于3D-ILC技术,在完整巴西圆盘内部制作平行双内裂纹,开展含60°双内裂纹单轴压缩试验,记录裂纹扩展过程,得到裂纹起裂及破坏荷载,分析双内裂纹相互作用下的应力双折射规律、裂纹扩展形态及断口特征。基于M积分及应变能密度因子理论进行数值模拟,揭示KⅠ、KⅡ、KⅢ的分布规律,实现双内裂纹扩展路径及平行裂纹相互作用模拟,并与试验进行对比。结果表明:1)基于3D-ILC的平行双内裂纹扩展破坏试验规律显著,证明了该技术在多内裂纹相互作用试验研究中的适用性;2)试样裂纹形态主要有上翼裂纹、下翼裂纹、竖直裂纹及贯穿型裂纹,翼裂纹断口光滑区为Ⅰ-Ⅱ型复合裂纹,裂纹侧面为Ⅰ-Ⅱ-Ⅲ型复合裂纹,呈现矛状断口;3)含60°双内裂纹试样破坏荷载为完整试样的17.73%,内裂纹扩展速度与加载力为非线性关系;4)双内裂纹尖端之间存在屏蔽作用,使扩展呈现明显反对称的裂纹形态;5)基于M积分的K分布及基于应变能密度因子理论裂纹扩展路径与试验规律一致。结果为3维内裂纹Ⅰ-Ⅱ-Ⅲ型复合断裂及多裂纹相互作用研究提供了物理试验及数值模拟参考。

威远构造W202区块龙马溪组龙_(1)^(1)亚段页岩气储集层岩石学特征

为明确四川盆地川西南地区低陡褶皱带威远构造页岩储集层岩石化学成分及矿物性质与含气性的关系,选取威远构造W202区块下志留统龙马溪组岩心样品,对岩石化学元素、页岩矿物类型及特征、有机碳含量与吸附能力等进行研究。研究表明:龙马溪组龙11亚段岩性主要为灰质(云质)页岩、硅质页岩、炭质页岩、黏土质页岩;矿物类型以陆源矿物、自生矿物、生物碎屑和少量有机质为主;纵向上发育4个小层,但其岩石化学特征存在明显差异,其中,龙1^(1)Ⅰ小层发育石英,脆性好,多见黄铁矿,有机质丰度高,吸附能力强,为页岩气优质储层。该研究为页岩气勘探和开发方案调整提供技术支持。

Microstructure and mechanical properties of heat affected zone in multi-pass GMA welded Al-Zn-Mg-Cu alloy

Microstructure and mechanical properties of the heat affected zone(HAZ)in multi-pass gas metal arc(GMA)welded Al Zn Mg Cu alloy plates were investigated,based upon which the mechanical anisotropy and fracture mechanism were analyzed.The microstructure and composition were analyzed by scanning electron microscope(SEM)and energy dispersive spectroscope(EDS).X-ray diffractometer(XRD),transmission electron microscope(TEM)and selective area electron diffraction(SAED)were used to analyze the phase composition.The distribution of microhardness was identified as gradual transition and tensile strength had a tendency to decrease first and then increase.The distribution of nano-sizedη(MgZn2)particles in theα(Al)matrix and Al2MgCu phase determined the tensile performances along the thickness direction and led to the formation of ductile/brittle composite fracture in the HAZ.The continuous distribution of Al2MgCu phase in the strip intergranular precipitates gave birth to premature cracks and the brittle fracture region.The precipitated particles coarsening also led to the deterioration of mechanical properties.

First-principles and experimental investigations on ductility/brittleness of intermetallic compounds and joint properties in steel/aluminum laser welding

Morphology,distribution,composition,forming ability,structural stability and intrinsic mechanical properties of the intermetallic compounds(IMCs)formed in steel/aluminum laser welding were determined through scanning electron microscope,energy dispersive spectrometer,X-ray diffractometer and first-principles calculation.It was found that the mechanical properties of the joint are limited by the Fe−Al IMCs,whose brittleness is attributed to the orbital hybridization between Al(s),Al(p)and Fe(d).However,the joint properties are improved by adding interlayer,which is ascribed to some changes of electronic structure of the generated IMCs.The transition mechanism of IMCs changing from brittle to ductile is mainly due to the weak ability of interlayer elements to attract electrons.The mechanical properties of the joint are closely related to the ductility or brittleness of the IMCs.Moreover,the addition of Ti foil interlayer effectively improves the mechanical properties of the joints,which means that the experimental verification is in good agreement with the theoretical calculation predictions.

A new measurement method of crack propagation rate for brittle rock under THMC coupling condition

A new electrical method of conductive carbon-film(with waterproof and anticorrosion ability)was proposed to continuously measure crack propagation rate of brittle rock under THMC coupling condition.A self-designed coupling testing system was used to conduct THMC coupling fracture tests of the pre-cracked red sandstone specimens(where the temperature is only changed)by this new electrical method of conductive carbon-film.Calculation results obtained by the energy method coincide well with the test results.And the higher the temperature is,the earlier the crack is initiated and the larger the crack propagation rate and accelerated velocity are,which can prove the validity of the new electrical method.This new electrical method has advantages of continuously measuring crack propagation rate over the conventional electrical,optical and acoustic methods,and can provide important basis for safety assessment and cracking-arrest design of deep rock mass engineering.

Mechanical behavior and failure analysis of brittle sandstone specimens containing combined flaws under uniaxial compression

Based on the axial stress-axial strain curves,the effect of fissure angle on the strength and deformation behavior of sandstone specimens containing combined flaws is analyzed.The mechanical parameters of sandstone specimens containing combined flaws are all lower than that of intact specimen,but the reduction extent is distinctly related to the fissure angle.The results of sandstone specimens containing combined flaws are obtained by the acoustic emission,which can be used to monitor the crack initiation and propagation.The ultimate failure mode and crack coalescence behavior are evaluated for brittle sandstone specimens containing combined flaws.Nine different crack types are identified on the basis of their geometry and crack coalescence mechanism(tensile crack,hole collapse,far-field crack and surface spalling)for combined flaws.The photographic monitoring was also adopted for uniaxial compression test in order to confirm the sequence of crack coalescence in brittle sandstone specimens containing combined flaws,which recorded the real-time crack coalescence process during entire deformation.According to the monitored results,the effect of crack coalescence process on the strength and deformation behavior is investigated based on a detailed analysis for brittle sandstone specimens containing combined flaws by using digital photogrammetry.

Effect of quenching process on mechanical properties and ductile-brittle transition behavior of 28CrMnMoV steel

Effect of quenching process on the microstrucmre and mechanical properties of a kind of seamless tubes of steel 28CrMnMoV was investigated. Then, an investigation on the influence of two different quenching processes on the ductile-brittle transition behavior of this steel was undertaken. The ductile-brittle transition temperatures of the steel by two different quenching processes were also determined. The results show that a good combination of mechanical properties can be obtained through austenitizing experimental steel at 800 ℃ or 890 ℃ followed by tempering at 630 ℃. Ductile-to-brittle transition temperature of 28CrMnMoV steel austenitized at 800 ℃ followed by tempering at 640 ℃ is about -73 ℃, which is much lower than the value -37 ℃ when the steel was austenitized at 890℃ and then tempered at 650 ℃. This indicates that subcritical quenching process could decrease largely the ductile-to-brittle transition temperature of 28CrMnMoV steel.

Mechanical and electrochemical characteristics in sea water of 5052-O aluminum alloy for ship

The optimum corrosion protection potentials were examined for 5052-O Al alloy,which is mainly used in ships.Various electrochemical experiments were carried out and the surface morphologies of specimens were observed by scanning electron microscopy（SEM） in order to determine the optimum corrosion protection potential to overcome pitting,corrosion,stress corrosion cracking（SCC）,and hydrogen embrittlement in sea water.An optimum protection potential range of-1.3 V to-0.7 V was determined under the application of an impressed current cathodic protection（ICCP） system.The low current densities were shown in the range of-1.3 V to-0.7 V in the electrochemical experiments and good specimen surface morphologies were observed after potentiostatic experiment.

应力腐蚀断裂与声发射

本文探讨了30CrMnSiNi2A超高强度钢在不同环境条件下的应力腐蚀过程中声的发射特征和断裂机理。

回转支承环设计的几个重要问题

为了满足海上作业日益增长的重型起重任务的需要,在短期内应设计制造出新设备来。当然,陆上设备的使用经验被用来开发这类新设备。结果所形成的破坏促使有关当局把许多海上起重机的使用能力降低50%。

K_Ⅰ—K_Ⅲ复合型断裂试验研究

本文阐述了使用具有环形裂纹的30Cr2MoV钢制圆棒试样进行K_Ⅰ—K_Ⅲ复合型断裂试验研究的初步成果。采用裂纹起始开裂点为临界点,经过塑性区修正用线弹性断裂力学的概念和理论处理试验结果。试验结果与高强钢用失稳点进行试验的结果相近,表明用S判据作为断裂判据是安全的。

Y2O3掺杂对ZnO-B2O3-SiO2玻璃黏度及成玻能力的影响

探索Y2O3掺杂对55ZnO40B2O35SiO2玻璃黏度及成玻能力的影响,采用同步热分析仪(DSC)、热膨胀仪、高温旋转黏度计和傅立叶变换红外光谱仪(FTIR)等测试方法研究了Y2O3掺杂量对55ZnO40B2O35SiO2玻璃的特征温度、热膨胀系数、黏度和玻璃结构的影响。通过动力学脆性指数的计算推断Y2O3掺杂对玻璃成玻能力的影响。适量的Y2O3掺杂可以增大55ZnO40B2O35SiO2玻璃黏度以及成玻能力,降低玻璃的热膨胀系数和脆性指数,这主要是由于Y2O3掺杂对55ZnO40B2O35SiO2玻璃结构的影响所致。