天然裂缝复杂程度对致密储层破裂特征的影响     

尹陈  石学文  才博  文山师  梁天成  王欣  付海峰  韩福盛 《高校地质学报》2023,29(1):128-137

地层内部总存在孔隙、裂隙、层理、裂缝、断层等结构特征从而体现为地层地质非均质性,并在人工注采过程中发生不同尺度的破裂而体现为跨尺度的裂缝时空延展特征和致裂机理。以致密油为代表的非常规油气藏开采开发在我国油气产能中占比越来越大,并往往利用水力压裂储层改造技术产生人工裂缝以增强油气渗流而实现其规模经济开发;同时,这类低渗透油气藏亦是CO₂压裂、注入和封存的重要对象。文章基于真三轴大型物理模型水力压裂实验和工程尺度下水力压裂微地震监测结果,通过不同尺度裂缝/裂隙活动所致声发射和微地震事件的时空展布研究岩体多尺度裂缝的破裂特征。研究表明,无论是相对稳定的真三轴水力压裂,还是实际地质工程尺度下的水力压裂微,岩石原生裂缝、裂隙分布趋势和方位对裂缝扩展具有主控作用。  相似文献   

Velocity-porosity relationships in hydrate-bearing sediments measured from pressure cores,Shenhu Area,South China Sea     

Lin Lin  Jun Cao  Jin Qian  Jiu-jing Shang  Wei Zhang  Jin-gan Lu  Jin-qiang Liang 《China Geology》2022,5(2):267-275

Evaluating velocity-porosity relationships of hydrate-bearing marine sediments is essential for characterizing natural gas hydrates below seafloor as either a potential energy resource or geohazards risks. Four sites had cored using pressure and non-pressure methods during the gas hydrates drilling project (GMGS4) expedition at Shenhu Area, north slope of the South China Sea. Sediments were cored above, below, and through the gas-hydrate-bearing zone guided with logging-while-drilling analysis results. Gamma density and P-wave velocity were measured in each pressure core before subsampling. Methane hydrates volumes in total 62 samples were calculated from the moles of excess methane collected during depressurization experiments. The concentration of methane hydrates ranged from 0.3% to 32.3%. The concentrations of pore fluid (25.44% to 68.82%) and sediments (23.63% to 54.28%) were calculated from the gamma density. The regression models of P-wave velocity were derived and compared with a global empirical equation derived from shallow, unconsolidated sediments data. The results were close to the global trend when the fluid concentration is larger than the critical porosity. It is concluded that the dominant factor of P-wave velocity in hydrate-bearing marine sediments is the presence of the hydrate. Methane hydrates can reduce the fluid concentration by discharging the pore fluid and occupying the original pore space of sediments after its formation.©2022 China Geology Editorial Office.  相似文献   

Improved rotational hardening rule for cohesive soils and definition of inherent anisotropy          下载免费PDF全文

Andrés Nieto Leal  Victor N. Kaliakin  Meysam Mashayekhi 《国际地质力学数值与分析法杂志》2018,42(3):469-487

Improved, microfabric‐inspired rotational hardening rules for the plastic potential and bounding surfaces associated with the generalized bounding surface model for cohesive soils are presented. These hardening rules include 2 new functions, f_η and , that improve the simulation of anisotropically consolidated cohesive soils. Three model parameters are associated with the improved hardening rules. A detailed procedure for obtaining suitable values for these parameters is presented. The first 2 parameters affect the simulation of constant stress ratio loading where, because of the presence of f_η, the third parameter is inactive. The second new function, , accelerates the rotation of the plastic potential and bounding surfaces during shearing, which is particularly important for overconsolidated soils tested in extension. This paper also describes the proper manner in which to define the inherent anisotropy. This seemingly straightforward test has rarely been discussed in sufficient detail.  相似文献   

阳原泥河湾盆地台儿沟东剖面沉积相磁化率各向异性研究     

董进  迟振卿  王永  闵隆瑞  陈兴强  姚杜琳 《地质论评》2015,61(3):681-693

磁化率各向异性(Anisotropy of Magnetic Susceptibility:AMS)能揭示沉积物中磁性矿物的定向排列,用于判定水流大小和方向变化。目前,关于沉积微相的磁化率各向异性研究仍较少。本文通过对台儿沟东剖面进行高分辨率磁化率各向异性研究,发现各沉积微相和亚相的磁化率各向异性较大差异,对于水动力较大的沉积微相,如分支河道、水下支流河道、河口砂坝等,其磁化率和磁化率各向异性度相对较大;对于水动力较小的沉积微相,如分支间湾、天然堤等,磁化率和磁化率各向异性度次之;对于滨浅湖、前三角洲泥、沼泽等静水环境,磁化率和磁化率各向异性度最小。根据各沉积微相或亚相χ与P的相关系数变化,可将河湖相地层分为两段:其中,在7.8~90m深度范围内,χ与P的相关系数为正值;在之下90~130m深度范围内,χ与P的相关系数主要为负值。与郝家台、东谷坨剖面磁化率各向异性结果相似,台儿沟东剖面各沉积微相和亚相的磁化率最大轴主要倾向NNE和NNW方向,而磁化率最小轴主要倾向SW方向,表明泥河湾盆地的物源除了可能来自盆地东部外,还可能来自盆地西南部。  相似文献   

基于矢量波场分离的TI介质逆时偏移     

任丽娟  李振春  王延光  刘兴达  孙小东 《物探与化探》2015,(1):196-202

基于两步法分离各向异性矢量波波场,第一步,将各向异性波动方程进行相似变换(使其具有明确直观的运动学和动力学特征),使其投影在各向同性方向上;第二步,各向异性介质传播算子波场分离基础上的波形校正,将投影于各向同性方向上的波场校正回各向异性方向上,最终达到各向异性波场分离的结果。笔者首先对VTI介质进行试算,以证明其可行性;此外,将地表数据进行分解,即所采集到的多分量地震数据在进行偏移成像之前先进行数据分解,得到纯净的q P波数据、q SV波数据以及q SH波数据,通过地表数据的分解将成像过程变成一个可控过程,通过对地表数据输入的控制得到我们所希望的成像结果分量,可以减少无谓的计算;对Hess模型正演炮记录进行了数据分解,并对其进行了逆时偏移成像以验证理论的可行性。  相似文献   

Identification of karst features using seismic P-wave tomography and resistivity anisotropy measurements     

Abdullah?KaramanEmail author  Turhan?Karaday?lar 《Environmental Geology》2004,45(7):957-962

A football stadium with a capacity of a hundred thousand spectators is under construction over a karst terrain, 10 km west of the old town of Istanbul, Turkey. A large cavity of approximately 30 m³ was detected beneath the sports field through a number of boreholes so that a geophysical survey was required to further investigate a portion of the sports field. We utilized seismic refraction tomography and dc-electrical method with rotated Wenner array to delineate zones with solution voids and cavities. Total core recovery (TCR) was 5–15% from boreholes where zones with low velocities were identified through tomographic inversion, whereas TCR values were above 60% in zones with higher velocities. Both low velocity zones in the tomographic images and increasing resistivity anisotropy with depth appear to indicate that the cavity extends toward the west and south at a depth of approximately 8 m, although the southward and westward extension changes in character.  相似文献   

Inversion of Travel Times in Weakly Anisotropic Rock Samples   总被引：1，自引：0，他引：1  

Xuyao?ZhengEmail author  Alice?Tomaskova 《Pure and Applied Geophysics》2004,161(8):1709-1724

Based on the perturbation theory, inversion formulae for travel time of qP and qS waves in arbitrary weak anisotropy media are presented. The inversion formulae are linear expressions of elastic parameters expressed in terms of weak anisotropy (WA) parameters. The formulae of qS₁ and qS₂ waves have the same form and they can be used without identifying which wave is considered. A synthetic experiment similar to the measurement of rock sample in the laboratory is carried out to illustrate the efficiency of the presented inversion formulae. Two data sets for qP wave travel time from rock samples in the laboratory are inverted and 15 WA parameters are obtained.  相似文献   

Patchy distribution fields: survey design and adequacy of reconstruction     

Kalikhman  I.; Ostrovsky  I. 《ICES Journal of Marine Science》1997,54(5):809-818

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An automated full waveform logging system for high-resolution P-wave profiles in marine sediments     

Monika Breitzke  Volkhard Spieβ 《Marine Geophysical Researches》1993,15(4):297-321

An automated, PC-based logging system has been developed to investigate marine sediment cores by full waveform transmission seismograms. High-resolution P-wave velocity and amplitude attenuation profiles are simultaneously derived from the transmission data to characterize the acoustic properties of the sediment column.A pair of ultrasonic, piezoelectric wheel probes is used to generate and record the transmission signals travelling radially through the sediment core. Both unsplit and split cores are allowed. Mounted in a carriage driven by a stepping motor via a shaft the probes automatically move along the core liner, stopping at equidistant spacings to provide a quasi-continuous inspection of the core by the transmission data. The axial travel distance and the core diameter are determined by digital measuring tools.First arrivals are picked automatically from the transmission seismograms using either a threshold in the seismogram's envelope or a cross-correlation algorithm taking the zero-offset signal of both wheel probes into account. Combined with the core diameter these first arrivals lead to a P-wave velocity profile with a relative precision of 1 to 2 m s^–1. Simultaneously, the maximum peak-to-peak amplitudes of the transmission seismograms are evaluated to get a first idea on the amplitude attenuation along the sediment core.Two examples of gravity cores taken during a recent cruise of R.V. METEOR in the Western Equatorial Atlantic are presented. They yield that the P-wave profiles can be used for locating strong and fine-scale lithological changes, e.g. turbidite layers and slight variations in the sand, silt or clay content. In addition, the transmission seismograms and their amplitude spectra obviously seem to reveal a correlation between the relative amount of low-frequency spectral components and the sediment grain size, and thus provide a tool for the determination of additional, related physical or sedimentological parameters in future investigations.  相似文献   

Geographically weighted regression with parameter-specific distance metrics     

Binbin Lu  Chris Brunsdon  Martin Charlton  Paul Harris 《International journal of geographical information science》2017,31(5):982-998

Geographically weighted regression (GWR) is an important local technique to model spatially varying relationships. A single distance metric (Euclidean or non-Euclidean) is generally used to calibrate a standard GWR model. However, variations in spatial relationships within a GWR model might also vary in intensity with respect to location and direction. This assertion has led to extensions of the standard GWR model to mixed (or semiparametric) GWR and to flexible bandwidth GWR models. In this article, we present a strongly related extension in fitting a GWR model with parameter-specific distance metrics (PSDM GWR). As with mixed and flexible bandwidth GWR models, a back-fitting algorithm is used for the calibration of the PSDM GWR model. The value of this new GWR model is demonstrated using a London house price data set as a case study. The results indicate that the PSDM GWR model can clearly improve the model calibration in terms of both goodness of fit and prediction accuracy, in contrast to the model fits when only one metric is singly used. Moreover, the PSDM GWR model provides added value in understanding how a regression model’s relationships may vary at different spatial scales, according to the bandwidths and distance metrics selected. PSDM GWR deals with spatial heterogeneities in data relationships in a general way, although questions remain on its model diagnostics, distance metric specification, and computational efficiency, providing options for further research.  相似文献