共查询到17条相似文献，搜索用时 234 毫秒
1.
对于目前分布最为广泛的砂岩储层,压实和胶结等成岩作用会影响砂岩储层的物性、弹性等物理性质并最终决定岩石颗粒的接触性质和孔隙结构特征.根据前人的研究,定量表征岩石压实和胶结作用的参数主要有视压实率和视胶结率、成岩综合系数等.目前尚缺乏一套系统完整的实验方法来确定岩石的成岩系数.实际应用时,前人多根据经验公式和薄片资料来确定原始孔隙度和胶结物含量,误差较大,流程复杂.本文立足实验手段,在前人研究的基础上,提出了一套系统的实验室确定视压实率和视胶结率的方法.结果表明,实验获得的视压实率、视胶结率与孔隙度、渗透率以及分选系数等存在较好的相关关系,符合前人研究的结果. 相似文献
2.
近年来围绕四川盆地侏罗系陆相致密砂岩已取得了勘探突破,其中川中—川西过渡带具备形成大气田的地质条件,但对该套致密砂岩弹性性质变化规律的研究还较少,致使利用地震方法进行"甜点"储层预测的精度不高.本文利用四川盆地侏罗系沙溪庙组32块样品开展了系统的声学测量,在此基础上,分析了样品弹性性质的变化规律.结合X射线衍射矿物组分分析、扫描电镜、铸体薄片和岩石薄片特征确定了不同成岩作用对岩石储集性能的影响.研究结果表明,研究区致密砂岩储层表现为孔隙型储层,受差异性成岩作用影响,黏土含量、钙质含量和硅质含量的差异以及它们分布特征之间的差异对岩石弹性性质造成了很大的影响.在研究区对岩石物性及弹性性质有明显影响的成岩作用包括早期的钙质胶结作用、压实作用和溶蚀作用,因此针对不同时期的成岩作用对岩石弹性及物性的影响,利用接触-胶结模型、微分等效模量模型和临界孔隙度校正的Hashin-Shtrikman上限模型建立了研究区致密砂岩的岩石物理模型. 相似文献
3.
在泥质砂岩的岩石物理建模中,明确泥质砂岩中泥质胶结物的接触类型及其含量对正确认识泥质的胶结作用对泥质砂岩声速的影响以及合理地建立岩石物理模型至关重要.现阶段,尚未有实验室定量估算胶结泥质的方法,导致应用胶结砂岩理论模型预测胶结砂岩地层的声速时往往由于胶结物含量被高估从而导致预测声速结果偏高.本文通过观察铸体薄片中泥质与颗粒之间的接触关系和相对分布提出了一种区分胶结泥质和分散泥质的方法:与两个或两个以上颗粒接触的连续分布的泥质为胶结泥质;与一个颗粒接触或者不与颗粒接触的泥质为分散泥质.基于这一准则,本文基于像素拾取法估算了人造泥质砂岩的胶结泥质含量,并将胶结泥质含量作为胶结砂岩模型的输入参数优化CCT模型.对比原始模型,本文方法声速误差下降了20%,预测准确度显著提高.本文方法适用于弱胶结地层的岩石物理建模,能够准确的预测声速以结合地震和测井资料识别有利储层,定量评价储层参数. 相似文献
4.
针对Dvorkin 和Nur （1996） 提出的连续胶结声速理论（CCT）中的胶结半径表达式仅适用于孔隙式胶结疏松砂岩的局限性,通过胶结物与颗粒之间的空间几何关系,在胶结物中心厚度不为零的前提下,推导了胶结物胶结半径的一般表达式,并考察了胶结物中心厚度对疏松砂岩声波速度的影响,探讨了该表达式在基底式胶结疏松砂岩纵横波速度预测中的应用.结果表明：随胶结物中心厚度变大,纵、横波速度均减小,且孔隙度越大,胶结物含量越少,速度下降越快;孔隙度或胶结物含量不变时,纵横波速比随胶结物中心厚度的增大而增大;纵横波速比随孔隙度的变化规律与胶结物中心厚度有关,当胶结物中心厚度较小时,孔隙度增大,纵横波速比略微减小,而当胶结物中心厚度较大时,孔隙度的增大会引起纵横波速比略微增大;对于基底式胶结疏松砂岩,使用推广后表达式修正的CCT模型相对原CCT模型能够更好地预测其声波速度,同时发现,利用其纵横波速比无法预测由孔隙度或胶结物含量变化引起的疏松砂岩软硬的变化,但是在胶结物含量或孔隙度不变的情况下,纵横波速比可指示由胶结物中心厚度变化引起的疏松砂岩软硬的变化. 相似文献
5.
《地球物理学进展》2017,(3)
在岩心观察的基础上,结合常规、铸体薄片、扫描电镜、压汞和核磁共振等资料对鄂尔多斯盆地合水地区延长组长7段致密油储层岩石学、物性特征及孔隙结构特征进行了研究.结果表明合水地区长7油层组致密油储层储集空间以溶蚀孔隙和微孔隙为主,原生孔隙保留较少,孔喉连通性较差,总体表现为物性差和孔隙结构复杂的特征.储层经历较强的压实作用,胶结物类型主要为碳酸盐和粘土矿物,此外还发育较强的溶蚀作用.根据压汞曲线形态与压汞参数,结合核磁共振T_2谱特征,将长7致密油储层孔隙结构类型划分为四类.并分别阐明了压实作用、胶结作用、溶蚀作用及其微孔隙含量对不同类型孔隙结构的影响,并运用综合考虑了压实、胶结成岩作用以及微孔隙含量的成岩综合系数来阐明并定量表示成岩过程中多种成岩作用对孔隙结构改造的综合效应.成岩综合系数与T_2几何平均值具有良好的统计正相关关系,因此可以作为不同类型孔隙结构定量表征的理想参数.经过对影响孔隙结构特征的成岩作用类型和强度的深入剖析,可在成因机理分析的基础上通过成岩综合系数来实现储集岩孔隙结构的定量评价.同时通过T_2几何平均值可以反推储层在成岩演化阶段所经历的成岩作用类型及强度,进而实现储层精细评价. 相似文献
6.
了解储层岩石的介电特性在石油工业的各个方面都有重要的应用.小尺度裂隙是影响岩石介电性质的地质因素之一,获得裂隙对含裂隙岩石介电性质影响的定量关系具有重要的理论和实践意义.以含裂隙人造砂岩的三维微观数字结构为基础,通过基于三维有限差分算法计算的岩石介电性质与实验数据的对比验证数值计算方法的有效性.在此基础上,通过理论模型获得不同孔隙度基质的介电性质,并在不含裂隙人造砂岩的三维微观数字结构中人为添加以裂隙密度和纵横比为定量表征参数的裂隙,应用验证后的数值算法模拟随频率变化的含裂隙砂岩的介电性质,分析和研究不同孔隙度基质中定向排列裂隙对砂岩介电性质的影响.结果表明,当裂隙孔隙度随裂隙纵横比或裂隙密度发生改变时,含裂隙砂岩的介电性质与裂隙密度以及裂隙纵横比呈正相关关系,而当裂隙孔隙度保持不变时,含裂隙砂岩的介电性质随裂隙纵横比的减小而增大;裂隙参数的改变对不同基质孔隙度的含裂隙砂岩的介电性质的影响趋势较为一致,但随着基质孔隙度的减小,裂隙对砂岩介电性质的影响逐渐增大.裂隙参数和基质孔隙度对含裂隙砂岩介电性质影响的研究结果为基于介电特性的裂缝性油气储层的定量表征提供了依据,在油气勘探开发中具有重要的应用前景. 相似文献
7.
《地球物理学进展》2017,(6)
砂岩储层压实过程中孔隙度的变化规律,是成岩数值模拟与储层质量预测的核心研究内容之一.通过对前人提出的孔隙度表征参数与压实强度表征参数进行分析、甄别,对压实过程中孔隙度变化规律进行研究,建立了三类不同砂岩类型储层的孔隙度压实方程.结果表明,粒间体积百分比(粒间孔隙度、胶结物含量与杂基含量之和)与埋藏过程中骨架颗粒所承受的最大有效应力在描述压实减孔规律时具有明显的优势.压实过程中孔隙度的减小具有分段性,表现为较浅埋藏期的快速递减与较深埋藏期的缓慢递减或恒定不变,二者可用一个统一方程描述.压实方程中的常数β与砂岩中塑性颗粒的含量及其塑性级别有关,随塑性颗粒含量提高及其塑性增强,β值增大;刚性颗粒组成的砂岩储层β为0.058 MPa~(-1),含75%极高塑性岩屑的砂岩储层β高达0.146 MPa~(-1).建立的压实方程在三类不同砂岩类型储层的应用中,绝对误差最大3.1%,相对误差最大13.8%,取得了良好的效果. 相似文献
8.
《地球物理学进展》2020,(4)
为探讨浅层致密砂岩油藏储层成岩作用及孔隙演化问题,以鄂尔多斯盆地南部B油田延长组长3-长7油层组为研究对象,开展岩石学特征、成岩作用、孔隙演化研究.研究表明,B油田长3-长7油层组碎屑成分差异不大,长7油层组石英含量高,长6油层组长石、岩屑含量高,长3油层组云母含量高.长3油层组粒级分布相对较粗,其次为长7油层组,长6油层组粒级分布最细.从长3、长6至长7油层组,碳酸盐胶结物含量、黏土矿物总量、伊/蒙间层含量、伊利石含量逐渐增加,高岭石、绿泥石含量依次减小,成岩胶结、交代作用依次增强.成岩作用阶段为早成岩B期至中成岩A期.随油藏储层埋藏深度增加,成岩作用强度持续、不断增强.储层孔隙演化研究表明,长3、长6、长7油层组初始孔隙度接近,压实成岩作用过程中损失的孔隙度也比较接近.随油藏埋藏深度增加,成岩作用中胶结作用增强,溶蚀作用减弱.长6、长7油层组胶结作用明显强于长3油层组,长3油层组溶蚀作用明显强于长6、长7油层组.随埋深增加,绝对溶蚀作用减弱,相对溶蚀作用增强. 相似文献
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10.
基于岩石物理相约束的致密砂岩气储层渗透率解释建模 总被引：1，自引：0，他引：1
充分利用岩心、薄片和钻测井等资料,对四川盆地JQ区块须家河组须二段致密砂岩气储层的沉积微相、成岩相和裂缝相特征进行了研究.结果表明,须二段沉积以辫状河三角洲前缘为主,发育水下分流河道、河口坝和分流间湾等微相;根据成岩作用类型、强度、成岩矿物及其对储层物性的影响将储层划分为压实致密、碳酸盐岩胶结、伊蒙混层充填和不稳定组分溶蚀4种成岩相;裂缝相则以局部层段发育的近水平缝为主.通过三者的叠加与复合对储层岩石物理相进行分类命名,划分出了河口坝-不稳定组分溶蚀-近水平缝相等多种岩石物理相.然后按照岩石物理相对储层物性的建设与破坏作用对其进行聚类分析,归纳出了PF1～PF4四大类岩石物理相.通过建立每一类岩石物理相的孔隙度-渗透率关系表明,基于岩石物理相约束而建立的储层渗透率解释模型具有更高的精度.岩石物理相是揭示致密砂岩气储层成因机理并提高其物性参数测井解释精度的有效途径. 相似文献
11.
Forced imbibition was performed in reservoir sandstone by injecting water into a dry sample. The injection was monitored with X‐ray computed tomography and acoustic acquisition to simultaneously visualize the displacement of the fluid and quantify its presence by calculating saturation and P‐wave velocities. We observed a strong influence when changing the injection rates on the acoustic response. Upon decreasing the injection rate from 5 mL/h to 0.1 mL/h, P‐wave velocities decreased sharply: 100 m/s in 1 h. This behaviour is related to the partially saturated conditions of the sample (76% of saturation) before decreasing the injection rate. The air that is still trapped is free to move due to a decrease of pore pressure that is no longer forced by the higher injection rate. After 1 hour, P‐wave velocities started increasing with small changes in saturation. Stopping injection for 16 hrs decreased saturation by 8% and P‐wave velocities by 100 m/s. Restarting injection at 5 mL/h increased saturation to 76% while P‐wave velocities fluctuated considerably for 2 hrs until they stabilized at 2253 m/s. Through the computed tomography scans we observed a water front advancing through the sample and how its shape changed from a plane to a curve after decreasing the injection rate. 相似文献
12.
Influence of subsurface injection on time‐lapse seismic: laboratory studies at seismic and ultrasonic frequencies 
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下载免费PDF全文 Seismic monitoring of reservoir and overburden performance during subsurface CO2 storage plays a key role in ensuring efficiency and safety. Proper interpretation of monitoring data requires knowledge about the rock physical phenomena occurring in the subsurface formations. This work focuses on rock stiffness and elastic velocity changes of a shale overburden formation caused by both reservoir inflation induced stress changes and leakage of CO2 into the overburden. In laboratory experiments, Pierre shale I core plugs were loaded along the stress path representative for the in situ stress changes experienced by caprock during reservoir inflation. Tests were carried out in a triaxial compaction cell combining three measurement techniques and permitting for determination of (i) ultrasonic velocities, (ii) quasistatic rock deformations, and (iii) dynamic elastic stiffness at seismic frequencies within a single test, which allowed to quantify effects of seismic dispersion. In addition, fluid substitution effects connected with possible CO2 leakage into the caprock formation were modelled by the modified anisotropic Gassmann model. Results of this work indicate that (i) stress sensitivity of Pierre shale I is frequency dependent; (ii) reservoir inflation leads to the increase of the overburden Young's modulus and Poisson's ratio; (iii) in situ stress changes mostly affect the P‐wave velocities; (iv) small leakage of the CO2 into the overburden may lead to the velocity changes, which are comparable with one associated with geomechanical influence; (v) non‐elastic effects increase stress sensitivity of an acoustic waves; (iv) and both geomechanical and fluid substitution effects would create significant time shifts, which should be detectable by time‐lapse seismic. 相似文献
13.
Yongyang Sun Boris Gurevich Maxim Lebedev Stanislav Glubokovskikh Vassili Mikhaltsevitch Junxin Guo 《Geophysical Prospecting》2019,67(4):888-899
Quantifying the effects of pore-filling materials on elastic properties of porous rocks is of considerable interest in geophysical practice. For rocks saturated with fluids, the Gassmann equation is proved effective in estimating the exact change in seismic velocity or rock moduli upon the changes in properties of pore infill. For solid substance or viscoelastic materials, however, the Gassmann theory is not applicable as the rigidity of the pore fill (either elastic or viscoelastic) prevents pressure communication in the pore space, which is a key assumption of the Gassmann equation. In this paper, we explored the elastic properties of a sandstone sample saturated with fluid and solid substance under different confining pressures. This sandstone sample is saturated with octadecane, which is a hydrocarbon with a melting point of 28°C, making it convenient to use in the lab in both solid and fluid forms. Ultrasonically measured velocities of the dry rock exhibit strong pressure dependency, which is largely reduced for the filling of solid octadecane. Predictions by the Gassmann theory for the elastic moduli of the sandstone saturated with liquid octadecane are consistent with ultrasonic measurements, but underestimate the elastic moduli of the sandstone saturated with solid octadecane. Our analysis shows that the difference between the elastic moduli of the dry and solid-octadecane-saturated sandstone is controlled by the squirt flow between stiff, compliant, and the so-called intermediate pores (with an aspect ratio larger than that of compliant pore but much less than that of stiff pores). Therefore, we developed a triple porosity model to quantify the combined squirt flow effects of compliant and intermediate pores saturated with solid or viscoelastic infill. Full saturation of remaining stiff pores with solid or viscoelastic materials is then considered by the lower embedded bound theory. The proposed model gave a reasonable fit to the ultrasonic measurements of the elastic moduli of the sandstone saturated with liquid or solid octadecane. Comparison of the predictions by the new model to other solid substitution schemes implied that accounting for the combined effects of compliant and intermediate pores is necessary to explain the solid squirt effects. 相似文献
14.
We measured in the laboratory ultrasonic compressional and shear‐wave velocity and attenuation (0.7–1.0 MHz) and low‐frequency (2 Hz) electrical resistivity on 63 sandstone samples with a wide range of petrophysical properties to study the influence of reservoir porosity, permeability and clay content on the joint elastic‐electrical properties of reservoir sandstones. P‐ and S‐wave velocities were found to be linearly correlated with apparent electrical formation factor on a semi‐logarithmic scale for both clean and clay‐rich sandstones; P‐ and S‐wave attenuations showed a bell‐shaped correlation (partial for S‐waves) with apparent electrical formation factor. The joint elastic‐electrical properties provide a way to discriminate between sandstones with similar porosities but with different clay contents. The laboratory results can be used to estimate sandstone reservoir permeability from seismic velocity and apparent formation factor obtained from co‐located seismic and controlled source electromagnetic surveys. 相似文献
15.
为了研究孔隙流体对不同渗透率岩石地震波速度的影响,在实验室利用跨频带岩石弹性参数测试系统得到了应变幅值10-6的2~2000Hz频段下的地震波速度和1 MHz频率下的超声波速度,利用差分共振声谱法得到了频率600Hz岩石干燥和完全饱水情况下岩石声学参数.实验表明,在低饱和度下,致密砂岩在地震和超声频段下没有明显的频散;在高饱和度下纵波速度的频散变得明显.从干燥到完全水饱和条件,不同频率测量的致密砂岩的体积模量随岩石孔隙度增高而降低,且体积模量的变化量受岩石微观孔隙结构的影响较大.高孔、高渗砂岩无论在低含水度下还是在高含水饱和度下频散微弱,并且在地震频段下围压对于岩石纵横波速度的影响要大于频率的影响.高孔、高渗砂岩和致密砂岩不同含水饱和度下的频散差异可应用于储层预测,油气检测等方面,同时该研究可以更好地帮助理解岩石的黏弹性行为,促进岩石物理频散理论的发展,提高地震解释的精度. 相似文献
16.
A. Schubnel O. Nishizawa K. Masuda X. J. Lei Z. Xue Y. Guégen 《Pure and Applied Geophysics》2003,160(5-6):869-887
— A set of experiments on four samples of Oshima Granite at 15, 40 and 60 MPa confining pressure have been performed in order to investigate the damage behavior of granite submitted to deviatoric stress. In addition an experiment on one sample of Toki Granite at 40 MPa confining pressure was performed, in order to compare and elucidate the structural effects. Using acoustic emission data, strain measurements and elastic wave velocities allow to define consistently a damage domain in the stress space. In this domain, microcracking develops. The microcracking process is, in a first stage, homogeneous and, close to failure, localized. Elastic wave velocities decrease in the damage domain and elastic anisotropy develops. Using Kachanov's model (1993), elastic wave velocities have been inverted to derive the full second-order crack density tensor and characterize the fluid saturation state from the fourth-order crack density tensor. Crack density is strongly anisotropic and the total crack density close to failure slightly above one. The results indicate that the rock is saturated in agreement with the experimental conditions. The model is thus shown to be very appropriate to infer from elastic wave velocities a complete quantitative characterization of the damaged rock. 相似文献
17.
Sofia Lopes Maxim Lebedev Tobias M. Müller Michael B. Clennell Boris Gurevich 《Geophysical Prospecting》2014,62(5):1126-1142
Quantitative interpretation of time‐lapse seismic data requires knowledge of the relationship between elastic wave velocities and fluid saturation. This relationship is not unique but depends on the spatial distribution of the fluid in the pore‐space of the rock. In turn, the fluid distribution depends on the injection rate. To study this dependency, forced imbibition experiments with variable injection rates have been performed on an air‐dry limestone sample. Water was injected into a cylindrical sample and was monitored by X‐Ray Computed Tomography and ultrasonic time‐of‐flight measurements across the sample. The measurements show that the P‐wave velocity decreases well before the saturation front approaches the ultrasonic raypath. This decrease is followed by an increase as the saturation front crosses the raypath. The observed patterns of the acoustic response and water saturation as functions of the injection rate are consistent with previous observations on sandstone. The results confirm that the injection rate has significant influence on fluid distribution and the corresponding acoustic response. The complexity of the acoustic response —‐ that is not monotonic with changes in saturation, and which at the same saturation varies between hydrostatic conditions and states of dynamic fluid flow – may have implications for the interpretation of time‐lapse seismic responses. 相似文献