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2.
Well logs provide additional information from the borehole that cannot be derived from other subsurface investigations. Their analysis may bring supplementary features about the earth’s heterogeneities. In previous researches, the logs were modeled using fractional Brownian motions indexed by Hurst (or Hölder) exponents quantifying their global regularity degrees. Indeed, these monofractal models, characterized by the same Hurst exponent, do not allow to study the depth-evolution of the local Hurst parameter. In order to overcome this problem, we propose to model the logs using multifractional Brownian motions and suggest an algorithm, developed previously for financial time series, to estimate the local Hurst exponent function. First, the potential of this algorithm is assessed through its application on synthetic sonic log data simulated by the successive random additions method. We note that the estimated Hurst functions (or regularity profiles) are very close to the theoretical Hurst functions. Second, this analysis is extended to sonic logs data from the KTB pilot borehole (Germany). Using the resulted regularity profiles, we carry out a lithological segmentation and fault identification on the geological layers crossed by the well. We derived also a correlation between the Hurst value variation and the lithological changes. 相似文献
3.
三露天井田具有断层发育、地层缺失和重复明显、岩性种类较多等特点,岩性识别难度较大。为此,专门利用测井资料对三露天井田地层岩性进行了岩性识别研究。通过对14个天然气水合物钻孔不同岩性的测井响应特征分析,优选了自然伽马、中子和密度测井作为岩性识别敏感参数,并采用交会图技术制作了岩性识别图版,建立岩性划分标准,对三露天井田地层岩性进行识别与划分。利用测井资料能够识别7种主要岩性,包括砂岩、粉砂岩、泥质粉砂岩、粉砂质泥岩、泥岩、油页岩和煤等。根据岩性测井识别结果,三露天井田岩性分布特征在横向上表现为东部砂岩物性好,西部地区泥岩较为发育;纵向上表现为木里组地层砂泥比为4.48,含有煤层204.5 m;江仓组地层砂泥比为0.84,泥岩和油页岩较为发育,更有利于水合物赋存。测井岩性识别结果为寻找三露天井田天然气水合物有利储层奠定了基础。 相似文献
4.
根据地面地质、地震和钻井资料,进一步论述了博格达推覆构造确立的依据,建立了基本模式,进行了区带划分,研究分析了推覆构造的形成和演化.指出了各区段的特征,受力机制以及控油的主要因素. 相似文献
5.
Boreholes are the only sources for direct measurements of geological and geophysical characteristics of the shallow subsurface of the earth. Borehole imaging tool “Acoustic Televiewer (ATV)” is an advanced probe, which records 3D image of the bore hole wall and is used to obtain oriented images of bore hole and provides substantial information regarding lithology, structural information, detection of fractures and casing of the borehole. The images are highly sensitive to the presence of fractures, the delineation of which becomes accurate and reliable based on these acoustic images. Features identified on log-derived images can be correlated with core samples or can be used as substitute in the poor core recovery zones. In the present study, ATV log from a deep borehole drilled at Khadi Kolavan in Koyna-Warna region of Ratnagiri district, Maharashtra located west of the Western Ghat escarpment in the Deccan Volcanic province, India, is used for interpretation of structural characteristics of the formation. The same was correlated with other conventional logging methods such as resistivity and full waveform sonic (FWS) as well as core logging and rock quality designations (RQD) which generated new understanding of the basement and basalt cover in this region. 相似文献
6.
New generation high resolution gravity models derived from space-borne gravity data, integrated with land based surveys, have enabled understanding of regional gravity field over regions, which are till date considered to be inaccessible for land surveys, especially in mountainous terrains. In this study, we evaluate two high resolution gravity models EIGEN-6C4 and GO_CONS_GCF_2_TIM_R5 in order to understand its usability in identification of meso-scale regional geological features and lithological boundaries around the Karakoram shear zone, in Leh, India. The EIGEN-6C4 is a “hybrid” model integrating data from space-borne sensors and terrestrial data, whereas GO_CONS_GCF_2_TIM_R5 is a model derived from the latest space-borne GOCE sensor. Bouguer gravity anomaly has been derived for both the models and compared. It is seen that, the GOCE derived model pertains to the regional gravity field of the region and compares well with the regional derivative of the EIGEN-6C4 model. Further, the EIGEN-6C4 has been analyzed using horizontal derivatives (dx, dy), analytical signal (ANS) and tilt derivative (TDR) techniques. These, derived maps are then overlain on published geological map of the area to understand the correlation between sub-surface geology vis a vis gravitational signal. The major and distinct geological signatures as derived from the various derivative maps correlate well with the existing geological map. The source boundaries derived from the TDR map agrees reasonably well with the lithological boundaries. Further, the anomaly and derivative maps from EIGEN-6C4 indicates towards a possible continuation of the Shyok suture zone in the region. Therefore, for the given spatial extent of the area under consideration, the GOCE derived model represents the regional field, whereas the EIGEN-6C4 data and derivatives are of sufficient resolution for understanding the geological variability in and around the Karakoram shear zone. 相似文献
7.
Glutenite reservoirs are characterized by strong heterogeneity, large thickness, complex rock fabric, and low maturity in terms of structure and composition, which makes the division of sedimentary periods an arduous task. This restricts the exploration and development of oil and gas fields in glutenite reservoirs. Wireline logging signals, which contain rich geological information and record the sedimentary cycle of the strata, are sensitive to changes in the lithologic interface. Moreover, the formation microscanner image (FMI) method provides a complete lithologic profile of the formation and intuitively identifies sequence boundaries, unlike cores and conventional well logs. By integrating mathematical tools based on time–frequency analysis technology of multiscale wavelet transform and FMI as the geological constraint, a sensitive logging curve was selected to delineate the sedimentary cycles of a glutenite reservoir. Optimization of wavelet decomposition parameters was conducted by employing Morlet as the wavelet base, and the scale factors were screened by the direct power spectrum method. Taking the glutenite reservoirs of the Baikouquan Formation in the MA131 well block of the Mahu Sag as the research object, the sedimentary periods of the glutenite body of well MA15 were divided under seismic constraints. The results indicated that the abrupt interface of the wavelet coefficient curve of different scale factors closely corresponded to the interface of sedimentary cycles at distinct levels. This demonstrates the effectiveness of the proposed method. Subsequently, the dynamic time warping algorithm was employed for automatic stratigraphic well correlation. It is concluded that the proposed technique eliminates the overdependence on traditional methods, such as geological and well stratification information, as well as possessing superiority with regard to high precision, better flexibility, and convenient operation. 相似文献
8.
识别地层岩性是在地层对比,沉积相分析等地质研究中的重要任务,在岩心资源较少,测井资料较多的情况下,利用多元统计分析进行地层岩性识别则是一种有效方法,为此,本文在胜利油田永一沙田砾岩体实际资料的基础上,通过取心井岩心和相应测井曲线的对应特征分析,应用判别分析方法,挑选了对岩性识别能力强的测井参数,确定了相应的岩性识别函数,利用该函数可以快速反应不同深度点上的地层岩性,并绘制相应的岩性剖面图等,为进一 相似文献
9.
Geophysical well-log (bore-hole) data facilitate understanding of the physical properties of the subsurface formations as a function of depth measured in a well. In the present study, the wavelet transformation technique was applied to the well-log data of three wells in the Bombay High oil field, India, in order to identify depths to the tops of oil and/or gas formation zones (pay zones). Continuous wavelet transformation (CWT) was performed on gamma-ray, resistivity, neutron porosity and velocity log data sets in order to determine the space-localization of the oil and/or gas formation zones. The choice of a mother wavelet is important and largely depends on the data under investigation. We have applied a variety of wavelets to the different log data sets to not only identify the depths to the tops of formation zones, but also to determine the optimum wavelet that best characterizes the pay zones. On examination of scalogram plots of each log corresponding to each wavelet for their better resolution in identifying the formation boundaries, we have found that the scalograms corresponding to the Gaus1 wavelet appeared to give the best resolution in identifying the depths of pay zones in all the well-log data sets of all three wells. To further validate the above observation, a histogram analysis of CWT coefficients is made. This showed that, of all the wavelets considered for the present study, Gaus1 wavelet is the most appropriate and optimum for determining the space-localization of pay zones in all the well-log data sets considered in the present study. The depths of pay zones estimated from scalogram plots of logs agree well with those provided by the Oil and Natural Gas Corporation Ltd., India. 相似文献
10.
A maximum-likelihood procedure for segmenting digital well-log data is presented. The method is based on a univariate state variable model in which an observed log is treated as a time-series consisting of two terms: a Gauss-Markov signal remaining constant over a segment, and an additive Gaussian, but not necessarily stationary, noise. The signal jumps by a random amount at a segment boundary. The inverse problem of log segmentation consists of detecting the segment boundaries from a given log. The problem is solved using a Bayesian approach in which the unknown parameters, the locations of segment boundaries and the jumps in the signal value, are estimated by maximizing the likelihood function for the observed data. An algorithm based on Kalman smoothing and single most likelihood replacement (SMLR) procedure is proposed. The performance of the method is illustrated with a case study comprising of multisuite log data from an exploratory well. The method is found to be rapid and robust. The resulting segments are found to be geologically consistent. 相似文献
11.
In sedimentology, stratigraphic sequences and cycles are ordered by time spans and physical scales, such as thickness, and bounded by discontinuities, including unconformities or flooding surfaces. Spectral analysis based on wavelet transform (WT) maxima is proposed and used as a quantitative tool to identify multi-order stratigraphic boundaries and cycles in well log data. The proposed spectral analysis is based on quantitative analysis on the center frequencies and resolutions of Gaussian wavelets in time and frequency, and uses a combination of the WT maxima based on both the first order Gaussian wavelet having a high time resolution and the seventh order Gaussian wavelet having a high frequency resolution. WT maxima spectra, which can characterize the evolution of WT maxima across scales and periods along WT maxima lines concerned with sequence boundaries, are used to detect dominant spectral peaks corresponding to the time-period domain WT maxima and to determine WT maxima spectral slopes. The WT maxima spectral slopes are helpful for discriminating sequence boundaries from intrasequence cyclic variations in well log data, and the time-period domain WT maxima are used to relate the detected boundaries to relevant cycles. The interval WT maxima spectra and the stationary index, related to the WT maxima spectra, are introduced as indicators that can be used for the hierarchical ordering of the boundaries and cycles. Application of the proposed method to well log data shows that the suggested method is efficient in identifying multi-order sequences that relate well to the Milankovitch cycles. 相似文献
12.
There are different opinions about the Permian/Triassic boundary and its correlation in the Daxian-Xuanhan area because of lacking typical lithological symbols and fossil criterions. Especially, it is very hard to determine the Permian/Triassic boundary in the Daxian-Xuanhan buried areas. This brings many difficulties to geological research and oil and gas exploration. Based on field investigation and studies of well cores, newly found fossils, lithological characteristics and well log analyses, the authors discussed the Permian/Triassic boundary in the Daxian-Xuanhan area and brought forward a specific scheme for its determination and regional correlation. 相似文献
13.
北京西山石炭 二叠纪煤系分布区地质灾害类型 (尤其是采空区地面塌陷 )与处于同一地区的侏罗纪煤系有明显的差别。造成差别的因素很多。在区域构造位置、区域应力场分布格局、煤矿开采深度、煤系岩石组合和煤质特征、采区地形坡度、风化剥蚀条件、煤炭开采技术及工艺等因素中 ,煤系岩石组合和煤质特征是主要因素。对煤系岩石组合和煤质特征的研究成果表明 ,其变形变质特征是决定煤系岩石物理性质的重要因素。在北京西山的地质灾害调查和成因研究中逐步认识到 ,地质灾害类型及强度与煤系及煤层的物理性质关系密切。因此 ,煤系的变形变质特征研究 ,既是基础地质问题 ,也是工程地质问题 ,应是煤炭分布区与采空相关的地质灾害研究中的重要内容之一。 相似文献
14.
在中国大陆科学钻探CCSD-1井110～2 000 m井段实测资料的基础上,通过取芯井岩芯和相应测井曲线对应特征的分析,挑选出对岩性识别能力强的测井参数,应用多组判别分析方法,建立了研究区各类岩性的识别模型.应用该模型可对井剖面地层进行连续自动解释,获得整口井的岩性解释剖面图,为进一步的地质研究提供基础资料.最后将得出的结果与分层资料进行误差分析,以判断资料的可靠性和方法的实用性. 相似文献
15.
针对矿产资源勘探数据的特点,研究了适合地质体信息三维可视化的体绘制模型和空间插值算法。基于IDL软件平台,开发了三维数据可视化软件;该软件能够快速、准确地将地质体的物性特征展示出来。最后,以内蒙古某金属矿床钻孔资料为例,对建立的三维可视化方法技术进行了应用检验,取得了较好的应用效果。 相似文献
16.
This study shows how wavelet analysis can be used on well log and drill core data to identify cyclicity in sedimentary sequences. Three possible methods for determining wavelength were investigated: the Morlet wavelet, the Fourier transform, and the semivariogram. When applied to several hypothetical signals similar to those observed in petrophysical measurements in hydrocarbon reservoirs, all three methods could identify the presence of cyclicity. Only the wavelet scalogram, however, gave a clear indication of when the cyclic element was present and where frequency changes occurred in the signal. To illustrate the wavelet analysis, we processed well log and core data from a well in the Ormskirk Sandstone and determined the wavelet coefficients for each zone and the wavelengths of the strongest cyclicities. The cyclicities observed corresponded well with sedimentary features of the formation (e.g., channels and channel sets). Also, ratios of the cyclicity wavelengths corresponded with ratios of the Milankovitch precession, obliquity, and eccentricity periods. This result is in agreement with other investigators, who have proposed that Milankovitch-driven climate changes exercised an important control on Ormskirk Sandstone deposition. 相似文献
17.
探讨了小波变换用于测井层序划分的一种方法。在论述了小波变换对信号时频分析的优势后, 介绍了连续小波变换的定义和一般步骤。以鲁西某钻井为例, 对迄今为止所能获得的分辨率最高、连续性最好的测井地质数据, 进行了连续小波变换, 提取小波变换系数的时频色谱信息。在此基础之上, 将不同时间 (深度) 尺度的旋回清晰地展现出来, 并探测到地层序列中不同级别的突变点, 从而实现对鲁西地区石炭二叠系层序、准层序的划分。这些探索为地层层序的划分提供了一种新的思路和有效途径。 相似文献
18.
The Neoproterozoic Wadi Kid metamorphic belt in southeastern Sinai in Egypt represents a structurally and metamorphically complex assemblage of metasedimentary and metavolcanic rocks folded into a series of ENE–WSW-trending antiforms and synforms. Geological mapping in this region is challenging, primarily due to difficult access, complexity of structures, and lack of resolution and areal integrity of lithological differentiation using conventional mapping techniques. Spectral ratioing of selected bands of Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data of the area, in synergy with geological field observation, proved effective in resolving geological mapping problems in the region. A new ASTER band-ratio image 4/7-4/6-4/10 is applied successfully for lithological mapping in the Wadi Kid area, showing improvement over previous techniques in detailing the main rock units. These are gneiss and migmatite, amphibolite, volcanogenic sediments with banded iron formation, meta-pelites, talc schist, meta-psammites, meta-acidic volcanics, meta-pyroclastics volcaniclastics, albitites and granitic rocks. Validating the use of the new ASTER band-ratio image relied on both calculating statistical optimum index factor (OIF) and matching interpreted lithological boundaries to field data and previously published geologic maps. The adopted ASTER band-ratio image demonstrates the benefit of using ASTER remote sensing data in lithological mapping of the Wadi Kid area and therefore for lithological mapping in the Arabian–Nubian shield and other arid areas. 相似文献
19.
不同于油气藏能源大多产于沉积地层之中, 金属矿成矿部位的地质条件要更为复杂多变。通常情况下矿体表现为不规则形状, 且连续性较差, 难以满足现有地震反射波法所以依据的镜面反射条件(徐明才等, 2009)。不同的围岩地震地质条件差异很大, 甚至同一种岩性受到蚀变、构造作用的影响, 表现出不同的阻抗特征, 当围岩与矿体间的波阻抗差异较小, 难以形成有效的反射波。在控矿构造方面, 通常大规模的构造对成矿具有控矿、控岩作用, 而与成矿部位密切相关的一般是小规模的断裂, 反射波较难识别。根据菲涅耳带理论, 当地质体的尺度小于地震波的一个波长时, 反射地震成像精度会骤降, 而来自这些小尺度、非均匀地质体产生的绕射波和散射波成像较反射波成像具有明显的高分辨率、甚至超高分辨率。利用绕射波成像能够探测和识别地下重要的构造信息, 如破碎带、断层、尖灭点、礁体边界、次火山岩、小尺度的侵入体、不规则盐丘体, 以及其他不连续的地质体(Karimpoul et al., 2015)。考虑金属矿围岩及控矿构造复杂, 矿体几何尺寸较小、形状不规则, 容易产生绕射波, 理论上利用地震绕射波识别这些地质体较反射波更具优势。 相似文献
20.
One main problem in the modeling of mineral deposits is to design a block model that divides the deposit into homogeneous subdomains. The spatial uncertainty in the geological boundaries becomes a critical factor prior to the modeling of the ore properties. For this reason, reducing the uncertainty of geological models leads to an improved mineral resource evaluation. This research work addresses the problem of updating the geological models by using actual online-sensor measurement data. A novel algorithm is provided, which integrates the discrete wavelet transform to the Ensemble Kalman Filter for assimilating online-sensor production data into geological models. The geological realizations in each time step are transformed to frequency coefficients and, after each assimilation step, the updated realizations are back-transformed to the original categorical distribution. Furthermore, a reconciliation process is performed to compare the online-sensor data derived from the production blocks and the updated realizations in each time step. The algorithm is illustrated through an application to the Golgohar iron deposit located in SW of Sirjan, Iran, and proves to reproduce the statistical parameters and connectivity values of the primary geological realizations.
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