基于Fisher判别分析的弹性属性参数致密碎屑岩岩性识别

致密碎屑岩岩性识别是储层预测中的难题之一,直接利用测井曲线或弹性参数很难识别。利用测井获得的纵横波资料,计算出了各种弹性参数,再利用Fisher判别方法,将砂岩、泥岩、粉砂岩3类岩性的样本投影到最佳的方向,实现各类样本之间最大程度的分离。试验结果表明,利用Fisher判别方法可以有效地识别砂岩和粉砂岩,判别率较高,为致密碎屑岩难动用储量的评价奠定了基础。

地震弹性属性的解释和应用

地震弹性属性参数与地层岩性密切相关,它的变化能够比较真实地反映出地层岩性的变化,因此,可以根据弹性属性参数及其变化,较直观、可靠地评价储层。在研究地震弹性属性参数基本意义的基础上,阐述了含油气储层的弹性参数的基本特征,探索了典型的含油气弹性参数属性剖面的解释方法和准则,并对国内外典型地震弹性参数属性剖面进行了解释,得出了有益的结论。该技术为隐蔽性岩性油气藏的勘探开发提供了新的技术支持,能够降低勘探开发风险。

四川盆地营山构造自流井组页岩油层小断层和裂缝高分辨率地震预测

应用常规地震裂缝预测技术对四川盆地营山构造自流井组页岩发育的小断层和裂缝进行预测,存在预测精度低、预测结果多解性强等问题。为解决小断层和裂缝高分辨率预测问题,提出沿层属性变化率小断层和裂缝预测方法。结果表明:该方法在页岩油层层状结构连续沉积特征情况下,基于地震资料开展叠后/叠前弹性属性反演,获得纵波阻抗、横波阻抗、纵横波速度比、密度等岩石弹性属性;通过地质力学属性建模,获得坍塌压力、破裂压力、弹性模量和泊松比等地质力学属性;按构造形态将弹性属性或地质力学属性划分出纵向多个小层后,评价多地震道间弹性属性和地质力学属性的相似性,得到高于地震资料分辨率的预测成果。四川盆地营山构造自流井组页岩油探井实钻和压裂评价结果验证了小断层和裂缝预测成果,证实了该方法的有效性。研究成果为页岩油层精细评价、井位部署、压裂工艺优化等工作提供技术支撑。

火山岩测井弹性响应特征及其正演模拟

准确描述深层气田火山岩的岩石弹性响应特征是常规测井地层评价、地震反演和储层预测的关键因素。在探讨火山岩的矿物组分特征并分析影响火山岩弹性响应特征的岩性、成岩和矿物组分的基础上，建立起“中子-密度交会”火山岩岩性分类方法；根据火山岩骨架矿物和充填矿物的基础弹性响应特征，应用Self Consistent模型正演不同岩性、物性和流体性质的岩石弹性响应特征；在标定多井实测密度、纵波速度和横波速度条件下，优化、调整了所建立的岩石物理模型参数，找出区域稳定的岩石物理响应规律，为地震储层预测奠定了基础。

渤海湾盆地东营凹陷砂岩储层地震特征及对岩石结构的指示

系统选取渤海湾盆地东营凹陷古近系各层段砂岩样品250块(以沙河街组为主),并在模拟储层条件下利用脉冲穿透法测试样品的纵、横波速度,在此基础上给出储层条件下速度-孔隙度、速度-密度等的统计岩石物理模型。样品在纵波速度-泊松比交汇图中呈现出两种主要变化趋势,分别对应泥质与钙质胶结物的影响。在每个变化趋势中,随泥质含量与钙质胶结物含量的增加,岩石结构从颗粒支撑逐渐表现为基质支撑,弹性波能量的传播也从通过颗粒接触边界转变为通过岩石基质传播。这是使砂岩样品测试结果表现出两种截然不同变化趋势的主要原因,为利用岩石物理特性从地震资料中提取岩石结构、沉积与成岩特征的信息提供了依据。

基于统计岩石物理的含气储层饱和度与孔隙度联合反演

从地震数据中得到饱和度与孔隙度等储层物性参数是进行储层评价的关键。利用Gassmann方程讨论了储层岩石骨架特征、孔隙流体特征对介质地震弹性性质的影响,研究结果表明利用地震弹性属性反演饱和度等物性参数有其实现的特定岩石物理基础,其一是在气/水/油多相流体中,气体的体积模量相对于水/油的体积模量具有一定的可比性,而不能被忽略;其二是岩石骨架的纵波阻抗等弹性属性对所赋存孔隙流体的变化较为敏感。这样岩石的纵波阻抗等弹性参数随含水饱和度变化的变化率会明显增大,从而降低了从地震弹性属性中求取饱和度的不确定性和不稳定性。考虑到孔隙度与饱和度对储层岩石弹性特征影响的相关性,给出了基于随机岩石物理模型的Bayesian技术对孔隙度与含水饱和度进行联合反演的方法和步骤,并将该方法运用于高孔隙度含气砂岩储层的孔隙度及含水饱和度的预测中获得了较好的应用效果。

基于核Fisher判别的碎屑岩储层流体识别

流体识别是致密碎屑岩储层预测中的难点之一.本文把核Fisher判别分析用于致密碎屑岩储层流体识别,首先较全面的介绍了核Fisher判别分析理论基础,再利用测井属性参数计算出弹性属性参数,并将这两类参数作为特征变量,最后进行核Fisher判别分析建模和致密碎屑岩储层流体识别.四川盆地XC地区致密碎屑岩储层流体识别结果表明,对致密碎屑岩储层中的气层和气水同层两类线性不可分的样本数据,使用核Fisher判别分析均能实现分离,说明该方法在识别致密碎屑岩储层流体识时准确率高,具有很好的应用前景.

地震岩性地貌体在薄储层沉积微相研究中的应用

针对薄储层区难以利用地震相开展沉积微相研究的难题,提出了地震岩性地貌体概念及其应用方法。地震岩性地貌体是反映沉积体岩性特征及其平面形态特征的一种地震属性体,不同于常规地震相分析侧重于剖面地震反射特征,它强调的是平面地震反射特征的指相意义,具有可量化表征性。指相属性的提取和井震标定是地震岩性地貌体沉积相分析的关键;叠前弹性模量属性分析、平面地震相模式标定和多信息融合解释是该项技术应用的必要途径和有效手段。这套方法在饶阳凹陷M构造带沉积微相研究中得到了成功应用。

Elastic and thermodynamic properties of Re_2N at high pressure and high temperature

First principles calculations are preformed to systematically investigate the elastic and thermodynamic properties of Re2N at high pressure and high temperature. The Re2N exhibits a clear elastic anisotropy and the elastic constants C11 and C33 vary rapidly in comparison with the variations in C12, C13 and C44 at high pressure. In addition, bulk modulus B, elastic modulus E, and shear modulus Gas a function of crystal orientations for Re2N are also investigated for the first time. The tensile directional dependences of the elastic modulus obey the following trend： [0001] [1211] [1010] [1011]EEEE〉〉〉 . The shear moduli of Re2N within the （0001） basal plane are the smallest and greatly reduce the resistance of against large shear deformations. Based on the quasi-harmonic Debye model, the dependences of Debye temperature, Grüneisen parameter, heat capacity and thermal expansion coefficient on the temperature and pressure are explored in the whole pressure range from 0 to 50 GPa and temperature range from 0 to 1600 K.

AVO技术在识别充填流体溶洞中的应用

寻找到充填流体的大型洞穴是碳酸盐岩油藏预测十分有意义的工作。塔河油田的试验表明,应用AVO技术可以有效地鉴别溶洞是否充填流体。溶洞充填流体之后,由于碳酸盐岩与流体之间存在很大的纵波波阻抗差异会形成强的纵波反射系数;同时,又由于流体内不传播横波,溶洞壁(包括顶低面)是横波的绝对反射界面,因而会形成强的横波反射。换句话说,充填流体溶洞既能形成强的纵波,又能形成强的横波。AVO分析对叠前地震数据进行弹性反演,从中提取出与横波有关的属性来指示充填流体的溶洞。

Some Properties of Si,Ge,and α-Sn Using Pseudopotential Theory

The pseudopotential theory beyond second order with our well established single parametric model potential is employed to compute total crystal energy, static bulk modulus, energy band gap at the point X on the Jones-zone face and pressure-volume relation （equation of state under pressure） of Si, Ge and α-Sn using Nagy＇s static local field correction function. The results are compared with those obtained using few other local field correction functions. The present results of total energy are in good agreement with the experimental data. Bulk modulus calculated by Nagy＇s screening function is perfectly matching with the experimental results for Ge and α-Sn. Some deviation is found in the value of energy band gap.

First-Principles Calculations of Structural,Elastic and Electronic Properties of Tetragonal HfO_2 under Pressure

Structural, elastic and electronic properties of tetragonal Hf02 at applied hydrostatic pressure up to 50 GPa have been investigated using the plane-wave ultrasoft pseudopotential technique based on the first-principles density- functional theory （DFT）. The calculated ground-state properties are in good agreement with previous theoretical and experimental data. Six independent elastic constants of tetragonal Hf02 have been calculated at zero pressure and high pressure. From the obtained elastic constants, the bulk, shear and Young＇s modulus, Poisson＇s coefficients, acoustic velocity and Debye temperature have been calculated at the applied pressure. Band structure shows that tetragonal Hf02 is an indirect band gap. The variation of the gap versus pressure is well fitted to a quadratic function.

Weak fatigue notch sensitivity in a biomedical titanium alloy exhibiting nonlinear elasticity

It is well known that metallic materials exhibit worse fatigue damage tolerance as they behave stronger in strength and softer in modulus. This raises concern on the long term safety of the recently developed biomechanical compatible titanium alloys with high strength and low modulus. Here we demonstrate via a model alloy, Ti-24 Nb-4 Zr-8 Sn in weight percent, that this group of multifunctional titanium alloys possessing nonlinear elastic deformation behavior is tolerant in fatigue notch damage. The results reveal that the alloy has a high strength-to-modulus（σ/E） ratio reaching2% but its fatigue notch sensitivity（q） is low, which decreases linearly from 0.45 to 0.25 as stress concentration factor increases from 2 to 4. This exceeds significantly the typical relationship between σ/E and q of other metallic materials exhibiting linear elasticity. Furthermore, fatigue damage is characterized by an extremely deflected mountain-shape fracture surface, resulting in much longer and more tortuous crack growth path as compared to these linear elastic materials. The above phenomena can be explained by the nonlinear elasticity and its induced stress relief at the notch root in an adaptive manner of higher stress stronger relief. This finding provides a new strategy to balance high strength and good damage tolerance property of metallic materials.

Analyzing and modeling rheological behavior of liver fibrosis in rats using shear viscoelastic moduli

The process of liver fibrosis changes the rheological properties of liver tissue.This study characterizes and compares liver fibrosis stages from F0 to F4 in rats in terms of shear viscoelastic moduli.Here two viscoelastic models,the Zener model and Voigt model,were applied to experimental data of rheometer tests and then values of elasticity and viscosity were estimated for each fibrosis stage.The results demonstrate that moderate fibrosis（≤F2） has a good correlation with liver viscoelasticity.The mean Zener elasticity E1 increases from（0.452±0.094） kPa（F0） to（1.311±0.717） kPa（F2）,while the mean Voigt elasticity E increases from（0.618±0.089） kPa（F0） to（1.701±0.844） kPa（F2）.The mean Zener viscosity increases from（3.499±0.186） Pa·s（F0） to（4.947±1.811） Pa·s（F2） and the mean Voigt viscosity increases from（3.379±0.316） Pa·s（F0） to（4.625±1.296） Pa·s（F2）.Compared with viscosity,the elasticity shows smaller variations at stages F1 and F2 no matter what viscoelastic model is used.Therefore,the estimated elasticity is more effective than viscosity for differentiating the fibrosis stages from F0 to F2.