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1.
Nestor A. Rivera S. Ray Jerry L. Jensen Andrew K. Chan Walter B. Ayers 《Mathematical Geology》2004,36(5):529-543
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
2.
Identification of sharp and discontinuous lithological boundaries from well log signal stemming from heterogeneous subsurface structures assumes a special significance in geo-exploration studies. Well log data acquired from various geological settings generally display nonstationary/nonlinear characteristics with varying wavelengths and frequencies. Modelling of such complex well-log signals using the conventional signal processing techniques either fails to catch-up abrupt boundaries or at the best, do not provide precise information on insidious lithological discontinuities. In this paper, we have proposed a new wavelet transform-based algorithm to model the abrupt discontinuous changes from well log data by taking care of nonstationary characteristics of the signal. Prior to applying the algorithm on the geophysical well data, we analyzed the distribution of wavelet coefficients using synthetic signal generated by the first order nonstationary auto-regressive model and then applied the method on actual well log dataset obtained from the KTB bore hole, Germany. Besides identifying the formation of layered boundaries, the underlying method also maps some additional formation boundaries, which were hitherto undetected at the KTB site. The results match well with known geological lithostratigraphy and will be useful for constraining the future model of KTB bore hole data. 相似文献
3.
Identification with accuracy of prospective and dry zone from well log data is of prime importance in reservoir or hydrocarbon studies. This issue has greater stake, where in return many conventional methods have been established. The purpose of this study is to recognize the hydrocarbon and non-hydrocarbon bearing portion within a reservoir by using a non-conventional technique. Application of rescaled range (R/S) analysis and wavelet-based fractal analysis (WBFA) on the wire-line log data to obtain the pre-defined hydrocarbon (HC) and non-hydrocarbon (NHC) zones by their fractal nature is demonstrated in this paper. Among these two techniques, the WBFA tool has provided more prolific results. Applicability of the proposed approach is tested with the help of the most commonly used well log data like self-potential, gamma ray, and porosity log responses. These are used in the industry to distinguish several HC and NHC zones of all wells in the study region belonging to the Upper Assam Basin, India. The results are found to be of lower fractal dimension in this study for a particular log response having HC-bearing zones, which are mainly situated in a variety of sandstone lithology. On the other hand, NHC-bearing zones correspond to lithology with higher shale content categorized with higher fractal dimension. Hence, the WBFA technique can overcome the chance of misinterpretation, which is quite possible in the case of conventional reservoir characterization. 相似文献
4.
在砂岩型铀矿地浸工作中,需要精准的识别含铀渗透性地层的岩性界面。传统的地层岩性界面识别一般通过岩心地质观察、实验室分析和综合测井曲线的人工解释等手段,不仅价格高而且周期长。文章以三江盆地ZKQX2钻孔为例,介绍了对三侧向电阻率测井曲线进行连续小波和离散小波变换,绘制小波系数尺度图和高频小波系数曲线图,并综合这两种图件来识别地层岩性界面的方法。将使用该方法识别地层岩性界面的结果与综合岩性柱状图对比,两者具有很好的一致性,表明利用测井曲线的小波分析识别地层岩性界面具有良好的应用效果。 相似文献
5.
Surface reflection seismic techniques have the capability of mapping subsurface geological features without disturbing the rock mass. They also have an added capability of penetrating to a much deeper depth than any other geophysical technique, including the ground probing radar. However, the successful application of reflection seismic techniques in crystalline rocks has in general been more difficult than in sedimentary basins, because of the irregular geometry and low acoustic impedance contrasts across geological boundaries. In this paper, we describe the imaging of fracture zones in crystalline rocks. Effective data processing, carefully modified from the conventional approaches, was applied on two high-resolution field data previously collected by different contractors. The strategy included enhancement of the signal hidden under the large-amplitude scattering noise, through pre- and post-stack processing such as shot f-k filtering, residual statics and careful muting after NMO correction. Two sets of low S/N test data from Canada and Sweden are analyzed in this research. The reflected energy in these data sets appeared to be more closely related to fracturing than to lithologic boundaries. The major fracture zones at shallow depth have been mapped with the desired resolution and can be correlated to the available well-log and seismic crosshole tomographic data. Once the surface waves were removed, shallow reflectors in the fracture zones could be identified and analyzed on the field records. Focusing analysis of the seismic image was performed in the constant-offset section to investigate the trends of major fracture zones. The complex attributes were also analyzed to determine whether they could be applied to the shallow fracture zones. Instantaneous frequency plots outline the intense fracturing zone and instantaneous phase plots identify the major and minor fractures, and other coherent events with different dip attitudes which interfere with each other. 相似文献
6.
The braided channel sedimentary sand is a kind of common oil reservoir, which is characteristic of poor regularity structure and complicated oil water relation. Seismic trace can be remodeled by wavelet decomposition, namely seismic trace is decomposed into a series of different attribute wavelets. The different reflection is obtained by the different attribute wavelets, thus prediction accuracy of braided channel sedimentary sand is improved. The seismic signal treated by matching pursuit method has good focusing capability of instantaneous spectrum, based on which the seismic signal is simply and rapidly remodeled by time frequency decomposition. The seismic data of Kendong 701 area were processed based on matching pursuit time frequency decomposition. The results showed that the interpretability of oil reservoir was improved and the seismic reflection characteristics and drilling data were well related. The braided channel sedimentary sands of Minghuazheng and Guantao group strata in Kendong 701 area were predicted, and the results showed that the reservoir distribution had the obvious braided channel features. Based on the predictions, three wells were located and the prediction and drilled results were consistent. 相似文献
7.
In the well-log data processing, the principal advantage of the nuclear magnetic resonance (NMR) method is the measurement of fluid volume and pore size distribution without resorting to parameters such as rock resistivity. Preliminary processing of the well-log data allowed first to have the petrophysical parameters and then to evaluate the performances of the transverse relaxation time T 2 NMR. Petrophysical parameters such as the porosity of the formation as well as the effective permeability can be estimated without having recourse the fluid type. The well-log data of five wells were completed during the construction of intelligent models in the Saharan oil field Oued Mya Basin in order to assess the reliability of the developed models. Data processing of NMR combined with conventional well data was performed by artificial intelligence. First, the support vector regression method was applied to a sandy clay reservoir with a model based on the prediction of porosity and permeability. NMR parameters estimated using intelligent systems, i.e., fuzzy logic (FL) model, back propagation neural network (BP-NN), and support vector machine, with conventional well-log data are combined with those of NMR, resulting in a good estimation of porosity and permeability. The results obtained during the processing are then compared to the FL and NN regression models performed by the regression method during the validation stage. They show that the correlation coefficients R 2 estimated vary between 0.959 and 0.964, corresponding to the root mean square error values of 0.20 and 0.15. 相似文献
8.
9.
ZHANG Jian-min ZHAO Yong-zhong XU Jing HUANG Juan The Logging Company Jilin Petroleum Group Co. Ltd Songyuan Jilin China 《吉林大学学报(地球科学版)》2006,(Z2)
吉林油田同位素吸水剖面测井采用~(113)In同位素追踪技术,根据同位素追踪过程解释基本可以判断配水层段吸水情况。但是在注水井存在沾污、大孔道以及串槽等影响时,吸水面积确定比较困难。在同位素测井中增加井温、流量参数,通过多参数综合解释,不仅可以对沾污影响进行合理校正,确定准确的小层吸水量,而且能够正确判断各级封隔器、配水器的工作情况,在地层存在大孔道的情况下,确定地层的吸水面积。吸水剖面综合解释方法在吉林油田已普遍应用,见到明显的效果。 相似文献
10.
鄂尔多斯盆地NNW油区主力油层为三叠系延长组长6和长4+5层段,为河流相和湖相三角洲透镜状和部分席状砂体叠加而成,属于超低渗透率的致密砂岩非常规油藏。NNW油区老井侧重于单个砂体的开发,油层打开程度不完善大大降低了采油速度。通过使用椭圆锥泄油模型模拟,发现油井泄油半径小于50 m,井间存在大量剩余储量。研究提出使用多油层组合、分段压裂取代单个砂体开发模式,将全井段油层及油水同层一次压裂完井。同时提出利用水平井开发方式对NNW油区进行再次开发,水平井及分段压裂具有成倍提高油区产量和经济效益的潜力。通过分析发现油区具有再次开发的良好资源条件。 相似文献
11.
Po-Yi Chou Hung-Chieh Lo Shih-Meng Hsu Yen-Tsu Lin Chi-Chao Huang 《Hydrogeology Journal》2012,20(6):1101-1116
The feasibility of using geological and geophysical well-log and borehole-televiewer data for the identification of hydraulically transmissive fractures is evaluated. Twenty-nine boreholes were drilled to a depth of 100?m in the middle-stream basin of Jhuoshuei River, Taiwan. Four criteria that assist in indicating the potential presence of permeable zones are proposed, including: lower gamma-ray response compared with the average response, divergence of the short normal-resistivity log relative to that of the long one, longer sonic travel time, and the appearance of discernible openings detected with the televiewer. With these, the transmissivities at the predetermined depths were estimated and verified by an in-situ hydraulic test. The statistical results indicate that, particularly in the mountainous area where a complex folded structure with a succession of synclines and anticlines is shown, the interpretation of lithologic conditions is not necessary to identify the presence of a relatively higher-permeability zone. Comparatively, the estimates of porosity and fracture aperture are the necessary premises to the prediction of hydraulically transmissive fractures. A joint consideration of all four criteria is found, allowing a less biased evaluation of the fracture transmissivity. 相似文献
12.
Akpabio G. Thompson George N. Jimmy Udofia K. Michael 《Central European Journal of Geosciences》2012,4(3):388-394
In this study, specific development of empirical models for estimation of laboratory thermal conductivities from wire line log thermal conductivity within the ambience of locally oriented wells located in the Niger Delta have been established. The laboratory thermal conductivity is characterised with high fidelity compared to wire line log thermal conductivity whose values vary as the dependence of lithology of the subsurface geomaterials, well effects, as well as the effects of the limited bed thickness of the adjacent lithological units of the Niger Delta where the study was stationed. The generalised equation k leff = 0.709 k weff + 0.188 is an empirically estimated model based on site variables (porosity, permeability and temperature) and constants (cementation factor, formation factor and tortuosity) of the locally oriented wells in the Niger Delta. It can be used to set bounds on the unstable wire line log thermal conductivity values within the 1-2.5 km depths where the oil-rich geomaterials in the Niger Delta are usually found. Equations have been established which show inter-convertibility between laboratory and wire line log thermal conductivity. These equations are considered useful in converting the available wire line log thermal conductivity data of nearby wells in the area to the usually desired and stable laboratory thermal conductivity. Various diagrams in 2-D and 3-D have been established to show the distribution of the parameters considered, and this could help the operating companies in the zone to predict the density of oil. 相似文献
13.
动静结合方法计算储层水淹后地层混合液电阻率技术及其在剩余油饱和度解释中的应用——以吉林扶余油田泉四段油层为例 总被引：2，自引：1，他引：1
针对国内注水开发油田水淹层测井解释中地层混合液电阻率(Rz)难以确定的问题,提出了一套动静结合确定Rz的新技术。该技术以开发井投产初期含水率资料为基础,结合静态研究成果,反演投产层的地层混合液电阻率(Rz),进而标定井筒中泥浆滤液电阻率(Rmf),在此基础上,应用自然电位测井的基本原理,可以计算垂向上各层的地层混合液电阻率(Rz)。对于初期投产层为单层和多层两种情况,提出了一种迭代算法,均能实现Rz的反演和Rmf的准确标定。以该技术为基础,针对已经进入高含水阶段的扶余油田泉四段油层开展水淹层测井资料的二次解释。通过与密闭取心检查井岩心分析数据对比,剩余油饱和度误差平均为6%。 相似文献
14.
In the Alberta Basin there is a significant difference in the content of Fe between formation waters from drillstem tests and formation waters from producing wells. This was demonstrated using a data set comprising 525 formation waters from drillstem tests and 107 formation waters from producing wells. Both a cross-plot of Mn and Fe in the two sets of formation waters and box plots of the same data sets showed that formation waters from producing wells have dominantly Fe>Mn, compared with those from drillstem tests which are characterized by Mn>Fe. Suspecting that “rust” contamination from well casing and ancillary equipment was the cause, the pH values of the samples were compared to see if the two data sets also differed in pH. It was demonstrated that not only are formation waters from drillstem tests less acidic than those from producing wells, but there is a systematic statistical trend of increasing acidity with age of the strata (temperature, depth, and increased amounts of the acid gases — H2S and CO2). The difference between the pH of formation waters from drillstem tests and producing wells is attributed to the partial scrubbing of the acid gases from the fluids produced during the drillstem test; this results in less acidic formation waters. Vanadium may also be enhanced in formation waters from producing wells. This note reports these differences and cautions too much reliance on values for Fe in waters from producing wells. 相似文献
15.
Eliseo Hernandez-Martinez Teresa Perez-Muñoz Jorge X. Velasco-Hernandez Armando Altamira-Areyan Luis Velasquillo-Martinez 《Mathematical Geosciences》2013,45(4):471-486
Well-log (radioactivity, density and resistivity) analysis constitutes a standard approach for inferring lithology from wells. However, due to inherent complexity of the signals (such as highly heterogeneous deep-water sedimentary sequences) lithology recognition is not straightforward. We used a rescaled range analysis, calibrated with cores, to recognize lithological patterns from signal recorded along wireline logs. The detected intervals coincide with zones of visual electro-facies associations proposed by geologist well-log interpreters. In addition, we propose a rescaled range multifractal analysis to identify ranges of well-log signal complexities, which could be related to sedimentary process variations at specific stratigraphic order cycles. 相似文献
16.
Multiresolution tectonic features over the Earth inferred from a wavelet transformed geoid 总被引：2，自引：0，他引：2
Geoid signals give information about the underlying density structure and can be used to locate the source depth of the mass anomalies. Wavelet analysis allows a multiresolution analysis of the signal and permits one to zoom into a specific area bounded by a particular length scale. The ability of wavelets to resolve the geoid signal into individual wavelength components without losing the spatial information makes this method superior to the more common spherical harmonic method. The wavelet analysis allows one to zoom into a specific area and look at the regional geology. We have used a wavelet transform of the geoid to study the regional geology of Japan and the Philippine Plate, South America, Europe, North America, East Africa and the Middle East, India and the Himalayas, China and Southeast Asia, and Australia. By filtering the Earth’s geoid anomalies with 2-D Gaussian wavelets at various horizontal length scales, one can detect the subduction zones along South America, the Aleutians, and the western Pacific; the Himalayas; the Zagros Mountains; the Mid-Atlantic ridge; and the island chains of the mid-Pacific. We have processed geoid data with a horizontal resolution down to approximately 200 km. Using an adjustable wavelet, one can detect structures that can only be picked up visually with much higher resolution spherical harmonic gravity data. We have also looked at the wavelength at which the maximum signal occurs over a range of scales. This method, known as E-max and k-max, is especially effective for detecting plate tectonic boundaries and ancient suture zones along with areas of strong non-isostatic gravitational potential due to high differential stress. These areas are likely to be at high risk of earthquakes. These methods will be especially useful to future studies of the geoid potentials of other planets, such as Mars and Venus, since they will allow careful studies of the regional geology variations with geoid data of the resolution available from satellites. 相似文献
17.
18.
水平井和大斜度井中阵列侧向测井响应数值模拟 总被引：1，自引：0，他引：1
针对水平井和大斜度井中阵列侧向电极系的工作原理,利用多电场叠加方式进行电场合成,采用三维有限元方法模拟仿真各个分电场的场分布,进而利用电场线性叠加原理得到阵列侧向测井响应。在基于计算机仿真的基础上,得到阵列侧向五条测井曲线的径向探测深度,阵列侧向径向探测深度要小于深侧向探测深度。考察了三维地层模型下井斜和侵入深度变化对阵列侧向测井响应的影响,分析了水平井和大斜度井中阵列侧向测井响应特征。模拟结果表明,在井斜小于15°时,阵列侧向测井响应受井斜影响小,可以不进行井斜校正;井斜超过60°的大斜度井以及水平井中,阵列侧向测井响应视地层厚度逐渐增大,测井响应值与直井条件下响应值差别较大,必须进行井斜校正。 相似文献
19.
Accurate knowledge of pore pressure is fundamental to any safe and economic well construction. Here, we present results that
are indicative of over pressure zones (OPZ) for five wells drilled under the Krishna–Godavari offshore basin (KGOB) at the
Eastern Continental Margin of India (ECMI). OPZ in areas of crustal flexuring can act as potential geohazard while drilling.
These wells locate at water depths of 515–1,265 m, where their penetrated-vertical-depth reaches up to 3,960 m in clastic
sediments. pore pressure gradient (PPG) and fracture pressure gradient (FPG) are estimated from acoustic log for all five
wells, while the Normal Compaction Trend (NCT) and pore pressure are calculated from Miller’s sonic equation. Top of OPZ is
indicated by values that are higher than the NCT; departure from NCT is observed at depth intervals of 1,320–2,180 m, 1,700–3,960 m,
1,600–1,880 m, 1,420–2,609 m and 2,080–2,200 m for the respective Wells 1 through 5. The pressure data from Modular Dynamic
Tester (MDT) agree well with the pore pressure values obtained from the logs. The Overburden Gradient (OBG), PPG and FPG values
increase rather slowly with total depth in deeper-water of KGOB when compared to the wells located in shallow water depth.
Consequently, the operating safety margin between PPG and FPG decreases as the water depth increases, and this clearly leads
to an increase in the number of casing strings to reach the target depth. Certain basic conclusions on the potentiality of
natural hazard for drilling operations are drawn on the basis of these results, but evidently, further studies are warranted
to present a more composite picture of OPZ under KGOB. 相似文献
20.
牛庄洼陷是东营凹陷的一个典型超压单元,明确超压分布特征需要研究泥岩超压的预测模型.基于测井和钻杆测试(DST)资料,分析了牛庄洼陷现今压力特征和3口典型井泥岩超压段的测井响应特征.分析表明,牛庄洼陷超压主要发育在2 100 m以下的沙河街组第三段和第四段,超压泥岩段的测井响应特征呈现多样化,主要表现在视电阻率测井响应的不唯一性,这种不唯一性可能主要与特殊岩性如油页岩等有关.采用Eaton公式利用泥岩声波时差换算出泥岩压力,建立了泥岩计算压力与储层实测压力之间的关系模型,即泥岩超压预测模型,通过超压砂、泥岩声波时差异常幅值的对比分析了该预测模型的可靠性,并开展了误差分析.研究认为,利用泥岩声波测井资料,通过该模型能够预测牛庄洼陷泥岩超压层空间分布的大致轮廓. 相似文献