共查询到19条相似文献，搜索用时 281 毫秒
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岩石物理是研究储层参数和岩石弹性参数之间关系的基础,在储层特性和地震特性之间起到了桥梁作用.为了更加精细的识别岩性,更好的进行砂泥岩储层油气的识别和预测,需要基于岩石物理寻找有效的识别方法.本文基于微分等效介质理论构建了砂泥岩储层岩石物理模型.为了考虑砂泥岩储层流体分布的非均匀性,模型中采用了斑块状饱和理论.文中分析了砂泥岩弹性参数和储层物性之间的关系,给出了各物性参数对弹性参数的影响结果,并根据储层物性的影响绘制了弹性参数交会模板.不同于常规交会分析,该弹性参数交会模板综合考虑了孔隙度、含水饱和度、泥质含量和孔隙纵横比等参数的影响,更加真实地反应了储层的地下特征.该交会模板的优势在于可以合理的界定出储层的砂、泥岩范围,而且根据泥质含量等参数的不同,可以进一步界定储层岩性的范围,为储层岩性的精细识别提供了新的方法.通过实际井资料的应用,该交会模板做到了砂泥岩储层岩性的有效区分,另外根据交会模板中泥质含量的不同,由0.5到0.25,我们可以在地震剖面中做出砂岩储层范围的精细界定,较好地识别了岩性,为寻找储层提供可靠依据. 相似文献
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通过融合Gassmann方程和由微分等效介质理论建立的干岩石骨架模型--DEM解析模型,本文提出根据纵波(和横波)速度反演岩石等效孔隙纵横比进行储层孔隙结构评价和横波速度预测的方法.首先,利用Gassmann方程和DEM解析模型建立岩石的纵、横波速度与密度、孔隙度、饱和度和矿物组分等各参数之间的关系;其次,将岩石孔隙等效为具有单一纵横比的理想椭球孔,应用非线性全局寻优算法来寻找最佳的等效孔隙纵横比使得理论预测与实际测量的弹性模量之间的误差最小;最后,将反演得到的等效孔隙纵横比代入到Gassmann方程和DEM解析模型中构建横波速度.实验室和井孔测量数据应用表明,反演得到的等效孔隙纵横比可准确反映储层的孔隙结构,对于裂缝型储层如花岗岩,其孔隙纵横比通常小于0.025,而对于孔隙型储层如砂岩,其孔隙纵横比通常大于0.08.只利用纵波与同时利用纵、横波反演得到的孔隙纵横比结果几乎完全一致,而且由纵波构建的横波与实测横波吻合良好,说明本文提出的等效孔隙纵横比反演及其横波速度预测方法是有效的. 相似文献
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利用新方法制作出含可控裂缝的双孔隙人工砂岩物理模型,具有与天然岩石更为接近的矿物成分、孔隙结构和胶结方式,其中裂缝密度、裂缝尺寸和裂缝张开度等裂缝参数可以控制以得到实验所需要的裂缝参数,岩样具有真实的孔隙和裂缝空间并可以在不同饱和流体状态下研究流体性质对于裂缝介质性质的影响.本次实验制作出一组具有不同裂缝密度的含裂缝人工岩样,对岩样利用SEM扫描电镜分析可以看到真实的孔隙结构和符合我们要求的裂缝参数,岩样被加工成八面棱柱以测量不同方向上弹性波传播的速度,用0.5 MHz的换能器使用透射法测量在饱和空气和饱和水条件下各个样品不同方向上的纵横波速度,并得出纵横波速度、横波分裂系数和纵横波各向异性强度受裂缝密度和饱和流体的影响.研究发现流体对于纵波速度和纵波各向异性强度的影响较强,而横波速度、横波分裂系数和横波各向异性强度受饱和流体的影响不大,但是对裂缝密度的变化更敏感. 相似文献
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《地球物理学报》2021,64(6)
地震岩石物理建模作为表征油气储层物性参数与地震参数间映射关系的主流工具,鲜有应用于煤层气储层,关键制约因素在于煤层气储层特有的吸附气和双重孔隙的等效计算问题尚未有效解决.为此,本文将吸附气视为类似煤基质的固相,将双重孔隙分解为基质孔隙和裂隙两部分;尝试利用自相容近似模型计算煤基质、吸附气和基质孔隙混合后煤基质干骨架的等效纵、横波速度,通过Mori-Tanaka模型和Brown-Korringa各向异性流体替换理论加入裂隙和流体,以此构建煤层气储层岩石物理模型.在此基础之上,通过正演模拟分析基质孔隙参数、吸附气含量以及裂隙参数的等效纵、横波速度响应;基于模型反演基质孔隙和裂隙参数,并将基于模型预测的纵、横波速度与实测数据对比,论证所构建的煤层气储层岩石物理模型的合理性.进一步通过制作岩石物理量版,探讨煤层气"甜点区"界定的两个关键参数——吸附气含量和脆性指数与储层物性参数(基质孔隙度、裂隙孔隙度)以及地震参数间的关系.结果表明:吸附气含量的变化引起的纵、横波速度、纵横波速度比和纵波阻抗变化微弱,引起的流体因子参数(λρ和μρ)变化略显著;基质孔隙度变化引起的地震参数响应显著强于吸附气含量;裂隙孔隙度与两种脆性指数间均具有明显的负相关性,可认为是煤层气储层脆性的主要影响因素. 相似文献
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苏里格气田属于我国特大型气田之一,地震反演技术广泛应用在气田勘探开发阶段.对研究区已有的资料进行岩石物理分析发现,纵波阻抗不能够识别目的层段砂岩、泥岩以及含气层.为了克服这一困难,采用叠前反演技术对盒_8-山_1段岩性气藏进行了刻画.在测井资料质控下以分角度叠加数据体作为输入,可以输出阻抗剖面以及纵横波速度比、泊松比等岩石弹性参数,综合判储层的岩性、物性及含气性.研究结果表明:(1)纵波阻抗不能区分砂泥岩以及含气砂岩,砂岩含气后,纵波阻抗明显降低,且分偏移距叠加数据体的振幅随偏移距的增加而增加,属于第三类AVO;(2)利用Xu-White模型对缺失横波资料进行反演,反演横波与全波测井实测横波对比发现相似度极高;(3)从反演结果来看,砂岩含气后横波阻抗不变,可以指示砂岩,速度比和泊松比显示异常小值,可以刻画含气砂岩.实钻证明,叠前反演技术为最终的井位优选和储层评价提供了可靠的依据. 相似文献
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孔隙裂隙型砂岩横波速度预测方法 总被引：3，自引：2，他引：1
在地震资料的AVO分析以及储层预测的流体识别分析等中需要横波速度信息,然而目前多数地区缺少横波速度测井,既没有岩石物理测试也没有VSP提供的横波速度信息.以往AVO和储层反演中的横波速度通常依靠经验公式或从纵横波波速度比为常数的假设中得到.这些经验公式往往精度很低,对于AVO特性包括弹性阻抗等特性描述不准确.特别是对储层中流体变化引起的AVO异常无法准确描述.为了获得准确的横波速度信息,我们采用Gassmann方程为基础的孔隙介质理论以及Lee提出来的方法建立了孔隙介质的横波速度模型.以此模型为基础,利用Thomsen的裂隙介质理论建立更加符合实际的含有裂隙的孔隙砂岩模型.预测的横波速度与实际的横波速度的对比证明了本文方法的有效性. 相似文献
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南堡凹陷4号构造沙一段砂、泥岩纵波阻抗叠置严重,利用叠后纵波阻抗反演难以有效预测优势储层砂岩分布.为此,本文综合运用岩石物理分析、叠前同时反演和岩性与流体概率分析技术对南堡4号构造沙一段优势储层砂体进行预测.在测井资料预处理的基础上,通过岩石物理建模正演估算横波速度,并建立岩石物理量版,确定优势储层砂岩的敏感参数;再利用叠前同时反演技术对优势储层进行预测,获得纵波阻抗、纵横波速度比和密度数据体;最后应用贝叶斯岩相与概率分析技术将纵波阻抗和纵横波速度比数据体转化为易于分析的砂岩概率体和优势储层砂岩概率体.经实钻结果检验,预测结果与井实测结果吻合度高,表明叠前预测结果真实、可靠;同时结合研究区构造特征,揭示出NP4-55井东南部和PG1井区为沙一段有利开发目标区. 相似文献
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目前横波预测的方法大致可以分为两种:经验公式预测和理论岩石物理模型。由于经验公式预测一般具有区域性,研究者更重视岩石物理模型预测。目前大多数岩石物理模型预测横波的方法假定地下流体的物性参数(速度和密度)不受地层深度的影响,且孔隙扁率是恒定的,实际上这并不科学。因为矿物的体积模量和剪切模量随所处地层深度发生改变,而对于孔隙扁率则随颗粒形状、孔隙度等的变化有较大变化。针对这些情况,提出一种新的改进的Xu-White横波预测方法,并可取得较好的效果。 相似文献
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页岩岩石物理建模旨在建立页岩矿物组分、微观结构、流体填充与岩石弹性参数的关系.对四川盆地龙马溪组页岩进行岩石物理建模研究,针对页岩黏土含量高、层间微裂缝发育等特点,利用Backus平均理论描述页岩黏土矿物弹性参数,利用Chapman理论计算与水平微裂缝有关的VTI各向异性,并利用Bond变换考虑地层倾角的影响.提出以黏土矿物纵、横波速度和孔隙纵横比为拟合参数进行岩石物理反演的方法,并引入贝叶斯框架减小反演的多解性.由已知的黏土矿物纵、横波速度和孔隙纵横比作为先验信息,并以测井纵、横波速度作为约束条件建立反演的目标函数,同时利用粒子群算法进行最优化搜索.计算结果表明,基于先验约束和粒子群算法的反演方法能够较准确地反演黏土矿物的弹性参数、孔隙形态参数以及裂缝密度等参数.计算得到的黏土纵、横波速度较高,并且在一定范围内变化,这可能与龙马溪组页岩的黏土矿物组分中具有较高弹性模量的伊利石含量较高有关,同时也与黏土定向排列等微观物性特征有关.反演得到的裂缝密度与纵波各向异性参数ε呈明显的正相关,而与横波各向异性参数γ相关性较小.另外,页岩各向异性参数与黏土垂向的纵横波速度有较强的相关性. 相似文献
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储层砂岩微观孔隙结构特征不仅影响干燥岩石的弹性波传播速度,也决定了岩石介质中与流体流动相关的速度频散与衰减作用.依据储层砂岩微观结构特征及速度随有效压力变化的非线性特征,将其孔隙体系理想化为不同形状的硬孔隙(纵横比α0.01)与软孔隙(纵横比α0.01)的组合(双孔隙结构).基于孔弹性理论,给出软孔隙最小初始纵横比值(一定压力下所有未闭合软孔隙在零压力时的纵横比最小值)的解析表达式,并在此基础上利用岩石速度-压力实验观测结果给出求取介质中两类孔隙纵横比及其含量分布特征的方法.通过逐步迭代加入软孔隙的方法对基于特征纵横比的"喷射流"(squirt fluid)模型进行了扩展,以考虑复杂孔隙分布特征对岩石喷射流作用的影响及其可能引起的速度频散特征.相较于典型的喷射流作用速度频散模式,对于岩石中软孔隙纵横比及其对应含量在较宽的范围呈谱分布的一般情况,其速度频散曲线不存在明显的低频段和中间频段,速度随频率的增大呈递增趋势直至高频极限.这说明即使在地震频段,微观尺度下的喷射流作用仍起一定作用,同样会造成流体饱和岩石介质的地震速度与Gassmann方程预测结果有不可忽略的差异.本文是对现有喷射流模型的重要补充,也为利用实验数据建立不同频段间岩石弹性波传播速度的可能联系提供了理论依据. 相似文献
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An inclusion model, based on the Kuster–Toksöz effective medium theory along with Gassmann theory, is tested to forward model velocities for fluid-saturated rocks. A simulated annealing algorithm, along with the inclusion model, effectively inverts measured compressional velocity (VP) to achieve an effective pore aspect ratio at each depth in a depth variant manner, continuously along with depth. Early Cretaceous syn-rift clastic sediments at two different depth intervals from two wells [well A (2160–2274 m) and well B (5222–5303 m)], in the Krishna–Godavari basin, India, are used for this study. Shear velocity (VS) estimated using modelled pore aspect ratio offers a high correlation coefficient (>0.95 for both the wells) with measured data. The modelled pore aspect ratio distribution suggests the decrease in pore aspect ratio for the deeper interval, mainly due to increased effective vertical stress. The pore aspect ratio analysis in relation to total porosity and volume of clay reveals that the clay volume has insignificant influence in shaping the pore geometry in the studied intervals. An approach based on multiple linear regression method effectively predicts velocity as a linear function of total porosity, the volume of clay and the modelled pore-space aspect ratio of the rock. We achieved a significant match between measured and predicted velocities. The correlation coefficients between measured and modelled velocities are considerably high (approximately 0.85 and 0.8, for VP and VS, respectively). This process indicates the possible influence of pore geometry along with total porosity and volume of clay on velocity. 相似文献
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在Kuster-Toksöz（KT）模型与差分等效介质理论（DEM）结合过程中,通过用孔隙包含物逐渐替换基质的方法获得孔隙介质的岩石弹性模量。现有方法每次替换的孔隙体积是常量,而基质体积不断减小,实际参与替换的包含物体积与孔隙包含物计算体积是不同的。本文通过改进每次替换的孔隙体积计算公式,使得替换体积随迭代次数的增加而逐渐减小,保持替换体积相对基质体积的比率不变,在迭代次数足够大的条件下使得该比率足够小,满足了K-T计算公式的要求,计算结果更接近理论值。测试结果显示:随着孔隙度的增大,岩石等效弹性模量逐渐收敛于孔隙包含物的弹性模量,说明本方法与物理规律一致;与现有的KT迭代方法相比,采用本方法的计算结果与Xu-White模型更接近,本方法提出孔隙包含物的实际体积与计算体积的计算式更符合KT模型孔隙切分过程。 相似文献
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孔隙纵横比是描述多孔岩石微观孔隙结构特征的重要参数,目前用于获取岩石完整孔隙纵横比分布的经典模型为David-Zimmerman(D-Z)孔隙结构模型,该模型假设岩石由固体矿物基质、一组纵横比相等的硬孔隙以及多组纵横比不等的微裂隙构成,并认为固体矿物基质和硬孔隙均不受压力影响,在此基础上,利用超声纵横波速度的压力依赖性反演岩石硬孔隙和各组微裂隙的孔隙纵横比及孔隙度.该方法的关键点在于以累积裂隙密度为桥梁,借助等效介质理论建立了岩石弹性模量和孔隙纵横比之间的内在联系.但在D-Z模型中,多重孔隙岩石累积裂隙密度的计算直接由单重孔隙裂隙密度公式实现,这种近似导致该模型在许多情况下难以获得良好的反演精度.为了完善经典D-Z模型,本文提出了一种基于虚拟降压的孔隙纵横比分布反演策略,通过多个假想降压过程实现累积裂隙密度的准确计算,并将基于DEM和MT的经典D-Z模型推广到KT和SCA中,结合四种等效介质理论建立了一套完整的反演流程.采用一系列砂岩和碳酸盐岩样品,测试了反演流程在实际岩芯孔隙纵横比提取中的应用效果,研究结果表明:与D-Z模型相比,本文方法的模拟结果与实际数据吻合更好,并同时适用于砂岩和碳酸盐岩;此外,通过分析四种等效介质理论的模拟结果发现,本文方法并不十分依赖于等效介质理论的选择,这些理论获得的孔隙结构参数随压力的变化趋势基本一致,数值上仅存在略微差异,且这种差异随着压力的增大逐渐消失.本文方法是经典D-Z孔隙结构模型的重要补充,对岩石孔隙结构表征、流体饱和岩石速度预测以及孔间喷射流效应的模拟具有十分重要的意义. 相似文献
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We develop a semi‐empirical model which combines the theoretical model of Xu and White and the empirical formula of Han, Nur and Morgan in sand–clay environments. This new model may be used for petrophysical interpretation of P‐ and S‐wave velocities. In particular, we are able to obtain an independent estimation of aspect ratios based on log data and seismic velocity, and also the relationship between velocities and other reservoir parameters (e.g. porosity and clay content), thus providing a prediction of shear‐wave velocity. To achieve this, we first use Kuster and Toksöz's theory to derive bulk and shear moduli in a sand–clay mixture. Secondly, Xu and White's model is combined with an artificial neural network to invert the depth‐dependent variation of pore aspect ratios. Finally these aspect ratio results are linked to the empirical formula of Han, Nur and Morgan, using a multiple regression algorithm for petrophysical interpretation. Tests on field data from a North Sea reservoir show that this semi‐empirical model provides simple but satisfactory results for the prediction of shear‐wave velocities and the estimation of reservoir parameters. 相似文献
16.
Wyllie's time-average equation and subsequent refinements have been used for over 20 years to estimate the porosity of reservoir rocks from compressional (P)-wave velocity (or its reciprocal, transit time) recorded on a sonic log. This model, while simple, needs to be more convincingly explained in theory and improved in practice, particularly by making use of shear (S)-wave velocity. One of the most important, although often ignored, factors affecting elastic velocities in a rock is pore structure, which is also a controlling factor for transport properties of a rock. Now that S-wave information can be obtained from the sonic log, it may be used with P-waves to provide a better understanding of pore structure. A new acoustic velocities-to-porosity transform based on an elastic velocity model developed by Kuster and Toksöz is proposed. Employing an approximation to an equivalent pore aspect ratio spectrum, pore structure for reservoir rocks is taken into account, in addition to total pore volume. Equidimensional pores are approximated by spheres and rounded spheroids, while grain boundary pores and flat pores are approximated by low aspect ratio cracks. An equivalent pore aspect ratio spectrum is characterized by a power function which is determined by compressional-and shear-wave velocities, as well as by matrix and inclusion properties. As a result of this more sophisticated elastic model of porous rocks and a stricter theory of elastic wave propagation, the new method leads to a more satisfactory interpretation and fuller use of seismic and sonic log data. Calculations using the new transform on data for sedimentary rocks, obtained from published literature and laboratory measurements, are presented and compared at atmospheric pressure with those estimated from the time-average equation. Results demonstrate that, to compensate for additional complexity, the new method provides more detailed information on pore volume and pore structure of reservoir rocks. Examples are presented using a realistic self-consistent averaging scheme to consider interactions between pores, and the possibility of extending the method to complex lithologies and shaly rocks is discussed. 相似文献
17.
Quantifying Damage, Saturation and Anisotropy in Cracked Rocks by Inverting Elastic Wave Velocities 总被引：1，自引：0，他引：1
Alexandre Schubnel Philip M. Benson Ben D. Thompson Jim F. Hazzard R. Paul Young 《Pure and Applied Geophysics》2006,163(5-6):947-973
Crack damage results in a decrease of elastic wave velocities and in the development of anisotropy. Using non-interactive
crack effective medium theory as a fundamental tool, we calculate dry and wet elastic properties of cracked rocks in terms
of a crack density tensor, average crack aspect ratio and mean crack fabric orientation from the solid grains and fluid elastic
properties. Using this same tool, we show that both the anisotropy and shear-wave splitting of elastic waves can be derived.
Two simple crack distributions are considered for which the predicted anisotropy depends strongly on the saturation, reaching
up to 60% in the dry case. Comparison with experimental data on two granites, a basalt and a marble, shows that the range
of validity of the non-interactive effective medium theory model extends to a total crack density of approximately 0.5, considering
symmetries up to orthorhombic. In the isotropic case, Kachanov's (1994) non-interactive effective medium model was used in
order to invert elastic wave velocities and infer both crack density and aspect ratio evolutions. Inversions are stable and
give coherent results in terms of crack density and aperture evolution. Crack density variations can be interpreted in terms
of crack growth and/or changes of the crack surface contact areas as cracks are being closed or opened respectively. More
importantly, the recovered evolution of aspect ratio shows an exponentially decreasing aspect ratio (and therefore aperture)
with pressure, which has broader geophysical implications, in particular on fluid flow. The recovered evolution of aspect
ratio is also consistent with current mechanical theories of crack closure. In the anisotropic cases—both transverse isotropic
and orthorhombic symmetries were considered—anisotropy and saturation patterns were well reproduced by the modelling, and
mean crack fabric orientations we recovered are consistent with in situ geophysical imaging.
Our results point out that: (1) It is possible to predict damage, anisotropy and saturation in terms of a crack density tensor
and mean crack aspect ratio and orientation; (2) using well constrained wave velocity data, it is possible to extrapolate
the contemporaneous evolution of crack density, anisotropy and saturation using wave velocity inversion as a tool; 3) using
such an inversion tool opens the door in linking elastic properties, variations to permeability. 相似文献
18.
This paper investigates the effects of uncertainty in rock-physics models on reservoir parameter estimation using seismic amplitude variation with angle and controlled-source electromagnetics data. The reservoir parameters are related to electrical resistivity by the Poupon model and to elastic moduli and density by the Xu-White model. To handle uncertainty in the rock-physics models, we consider their outputs to be random functions with modes or means given by the predictions of those rock-physics models and we consider the parameters of the rock-physics models to be random variables defined by specified probability distributions. Using a Bayesian framework and Markov Chain Monte Carlo sampling methods, we are able to obtain estimates of reservoir parameters and information on the uncertainty in the estimation. The developed method is applied to a synthetic case study based on a layered reservoir model and the results show that uncertainty in both rock-physics models and in their parameters may have significant effects on reservoir parameter estimation. When the biases in rock-physics models and in their associated parameters are unknown, conventional joint inversion approaches, which consider rock-physics models as deterministic functions and the model parameters as fixed values, may produce misleading results. The developed stochastic method in this study provides an integrated approach for quantifying how uncertainty and biases in rock-physics models and in their associated parameters affect the estimates of reservoir parameters and therefore is a more robust method for reservoir parameter estimation. 相似文献
19.
P－SV转换波的一种处理方法─叠前抽道集法 总被引：1，自引：0，他引：1
本文利用纵波和横波的迭加速度资料来计算Ｐ－ＳＶ波勘探中转换点的近似位置。再按转换点对Ｐ－ＳＶ波重新抽道集，得到可与反射资料ＣＭＰ道集相兼容的时间剖面图。利用理论模型对上述方法进行了可靠性检验，并用该方法对实际资料作了处理。同时还得到了实际资料的Ｐ波和Ｐ－ＳＶ波的彩色振幅比剖面图。结果表明：采用改进的叠前抽道集法所得到的剖面图具有很好的空间分辨率。 相似文献