Post-stack seismic inversion and attribute analysis in shallow offshore of Krishna-Godavari basin,India

Seismic attributes such as: amplitude envelope, instantaneous phase and cosine of instantaneous phase of 2D post-stack seismic data facilitates structural and stratigraphic interpretation of shallow marine offshore, Krishna-Godavari basin. Two seismic sections namely, X and Y oriented N-S passing through wells W-1 andW-2 respectively are considered for seismic attribute analysis and porosity prediction. The gamma ray log trend indicates deposition of cleaning upward sediment. Coarsening upward, clayey-silty-sandy bodies, making a series of about 50-60 m thickness, have been evidenced from the gamma ray log. An extensional structural style comprising growth faults is associated with the progradational style of deposition. Four seismic zones have been distinguished. These zones differ in amplitude, frequency and continuity of the reflectors. Channel sands of Cretaceous age of Raghavapuram shale are identified in well log, seismic section and its acoustic impedance section. Major stratigraphic horizons along with faults extending to basement are marked with the help of attribute analysis. Porosity is mapped from transformation of acoustic impedance. The shales/unconsolidated sediments measure a high porosity with low impedance and the more porous sands are in an intermediate range. The predicted impedance and porosity values may be erroneous beyond the drilled depth because of non availability of well log data for calibration.     

高精度分频相干加强技术在微小断层识别中的应用

随着致密油、页岩气等非常规能源领域勘探程度的加深,特别是水平井位的大规模部署,微小断层的准确识别比以往更加重要。本文利用扩散滤波技术在压制噪声的同时能够增强地震同相轴横向连续性、使断点更加清晰、以及微小断层在窄频带地震数据中断层特征明显的特点,提出了一种基于高精度快速匹配追踪的分频相干加强微小断层识别方法。与常规短时窗傅氏变换谱分解技术相比,基于匹配追踪的谱分解技术更适用于地震信号非平稳性的特点。为了在保证匹配追踪算法计算高效性的同时进一步提高计算精度,对其进行了相应的改进：采用可变尺度参数的Morlet小波构建时频原子库,利用二阶微分复数道分析技术得到高分辨率三瞬参数,最后给出了具体的实现步骤。实际数据应用表明,与常规相干体技术相比,分频相干加强技术对微小断层的反映更为清晰、准确,而且对河道边界和岩性发育区等地质信息也有更好的反映。这不但为非常规勘探（以水平井钻探及大规模压裂为核心技术）提供了更详细的地质信息,而且在高含水老油田的剩余油开发中也将发挥更大的作用。     

页岩气富集带地质控制因素及地震预测方法

首先对页岩气富集带的地质控制因素及各家的评价指标进行了探讨,认为页岩气的评价指标可以分为两大类：一类是评价页岩气量的多少,即资源因素,它决定了该区页岩气资源潜力及储量的多少,是页岩气资源评价、有利区块优选的关键指标。主要包括页岩厚度、有机质（TOC）丰度、干酪根类型、成熟度(Ro)、天然气含量及状态（游离、吸附）等。另一类决定了页岩气能否经济地开采出来,以及产量的高低,即所谓的“核心区”或“甜点”区。包括埋藏深度、页岩本身的矿物成分、脆度、孔隙度（裂缝）、渗透率以及原始地应力大小、方向及差异等。这两类指标共同控制了页岩气的富集和最终产量。因此,在页岩气勘探开发过程中,应首先利用地质和地球化学方法对第一类指标进行评价,从中优选出有利区块。在有利区块内,可以利用地震相关技术对第二类指标预测和评价,从中优选出适合钻井和开采的页岩气富集带或“甜点”区。根据对页岩气富集带（甜点）地质控制因素的讨论,可以将页岩气划分为“裂隙” 型页岩气藏及“脆性”型页岩气,两种类型均需位于弱应力各向异性区,以便于压裂过程中得到理想的复杂网状裂缝系统。笔者认为,对于“裂隙”型页岩气藏,几何地震属性分析技术（包括相干体、蚂蚁体、曲率体等）可以很好地刻画断层、隐伏断层及裂缝发育带,对这些成果的解释可以以玫瑰图的方式展示,从而可以揭示该区域的裂缝的主要发育方向及次要方向,进而推断该区的局部主应力方向,为水平井位部署提供依据。而对于“脆性”型页岩气藏,叠前反演技术、叠后反演技术可以揭示低泊松比(υ),纵横波速比等来进行有利目标（甜点）识别。曾经在常规油气勘探中发挥重要作用的地震技术,在页岩气等非常规油气资源勘探开发中,仍然是一种不可或缺的关键技术。     

A passive seismic approach to estimating the thickness of sedimentary cover on the Nullarbor Plain,Western Australia

Passive seismic approaches, using a single-station, enable rapid, cost-effective and non-invasive estimates of the thickness of sedimentary rocks overlying crystalline basement. This approach was applied to estimate the Cenozoic and Cretaceous succession beneath the Nullarbor Plain in southeastern Western Australia. Passive seismic data acquired at the majority of the 94 sites show a single, strong resonance frequency peak between 0.4 and 0.6 Hz suggesting an impedance contrast of a single subsurface layer. Modelling these resonance frequencies against known stratigraphy at 12 drill holes shows that this impedance contrast corresponds to the contact of the base of the Cenozoic–Cretaceous sedimentary succession of the Eucla and Bight basins with the crystalline basement. Data from the remaining sites produced sediment thickness estimates ranging from only tens of metres near the western edge of the Nullarbor Plain to over 860 m near its southern margin. Near this margin, rapid thickening of the sedimentary cover is coincident with an interpreted paleosea-cliff or indicative of localised faulting. Beneath the Western Australian portion of the Nullarbor Plain the sedimentary cover is on average 320 m thick with the succession thinning gradually towards the margins of the basin. A passive seismic approach is thus seen as a useful screening tool for the mineral exploration industry in areas that are under cover allowing for better targeting and cost-reduction in greenfields exploration.     

基于饱水页岩地震频段岩石物理测试的地震响应频散特征分析

页岩储层由于骨架和孔隙结构的微观非均质性,能够在地震频段内引起波诱导的孔隙流体流动相关的弹性频散和衰减,但声波测井和实验室超声实验测量频率段远超地震频段,不可避免产生测量速度和衰减差异。这里基于澳大利亚惠灵顿地区的页岩岩心在干燥和水饱和条件下地震频段的弹性和衰减测量结果,考虑频变反透射系数和衰减对地震波反射的影响,针对不同层厚的页岩储层开展地震响应计算,并利用Wigner-Ville分布时频分析技术讨论了页岩频散、衰减性质及层厚对其地震响应规律的作用。对于无明显速度频散和衰减的页岩储层,顶、底反射振幅的频变属性受调谐效应控制,主要呈现出低频异常和陷频特征;而对于速度频散和衰减强烈的储层,顶、底反射振幅的频变属性同时受到调谐效应与储层本身频散衰减性质的作用。干燥和含水页岩储层地震响应的频变性质差异有助于加深对含流体页岩地震响应特征的理解,而基于地震频段实测数据正演和时频分析技术,对于提高页岩的地震勘探精度和流体识别具有重要的作用。     

Estimation of petrophysical parameters using seismic inversion and neural network modeling in Upper Assam basin,India

Estimation of petrophysical parameters is an important issue of any reservoirs. Porosity, volume of shale and water saturation has been evaluated for reservoirs of Upper Assam basin, located in northeastern India from well log and seismic data. Absolute acoustic impedance (AAI) and relative acoustic impedance (RAI) are generated from model based inversion of 2-D post-stack seismic data. The top of geological formation, sand reservoirs, shale layers and discontinuities at faults are detected in RAI section under the study area. Tipam Sandstone (TS) and Barail Arenaceous Sandstone (BAS) are the main reservoirs, delineated from the logs of available wells and RAI section. Porosity section is obtained using porosity wavelet and porosity reflectivity from post-stack seismic data. Two multilayered feed forward neural network (MLFN) models are created with inputs: AAI, porosity, density and shear impedance and outputs: volume of shale and water saturation with single hidden layer. The estimated average porosity in TS and BAS reservoir varies from 30% to 36% and 18% to 30% respectively. The volume of shale and water saturation ranges from 10% to 30% and 20% to 60% in TS reservoir and 28% to 30% and 23% to 55% in BAS reservoir respectively.     

Attenuation of multiple waves using the continuous wavelet transform (CWT)

This paper describes how the continuous wavelet transform is used to filter multiple waveforms in both time and frequency domains. It is well suited to process the stationary signals, and it shows the signal in both time and frequency scales. This new approach was tested first on synthetic data and then on real data. The results obtained on both cases were good. The method consists of identifying the multiples on which we apply a normal move out using the multiple velocity law. The multiples will be aligned and the primary reflections will not be aligned. This operation allows locating the multiples in the time-scale domain. We compute the continuous wavelet transform (CWT for short) in order to focus on the patterns relative to seismic events. To filter the multiples, we define a zone with frequency and time bounds. These bounds are deduced from the projection of the seismic trace. Then an automatic mask is applied to the pattern to be isolated. Filtering in time–frequency domain is done by keeping only the wavelet coefficients that are outside the mask and assigning zero to the coefficients larger than a threshold amplitude inside the defined zone. The mask shape does not matter, which is not the case in classical filtering, where both the window size and shape play a key role. The mask is defined from three parameters: time, frequency, and the wavelet coefficients. To go back to the time domain, one has to compute the wavelet transform inverse of the trace. This procedure is repeated for all traces. To reset the traces to their initial positions, we apply the dynamic correction inverse with the same velocity law as the multiples. It turns out that the attenuation of multiples by the CWT works fine, in particular, the two identified multiples were quasi eliminated (Fig. 10).     

川西拗陷须五段非常规气形成条件分析

随着对非常规气蔵的研究方法和开采手段的升级,使页岩气得以开发。川西拗陷须五段常规的思维是把它作为烃源岩来认识的,运用非常规页岩气的研究理念和方法,针对川西拗陷两条野外剖面(莲花剖面、万家坪剖面)及6口取心井(XYHF-1井,XYHF-2井,X503井,FG5井,GH2井,MY1井)的岩心观察、取样分析测试,以分析川西拗陷须五段具有形成非常规气蔵的条件,并用3种不同的表征方法(激光共聚焦法、高压压汞法、氮气吸附法)对须五段内不同类型的岩石进行孔隙度、渗透率及其连通性时行表征,结果表明:细砂岩中不同类型孔隙的孔隙度为0.41%～6.65%,平均总孔隙度为2.14%;泥(页)岩的孔隙度为1.51%～5.99%,总孔隙度为2.70%。微米CT扫描发现须五段上亚段细砂岩的连通性好于下亚段,中亚段以粉砂岩为主,孔隙连通性差,有机质含量低;泥(页)岩的孔隙连通性也差,孔隙发育依附于有机质的发育,泥(页)岩样品的有机碳含量主要分布在0.5%～3%之间。综合评价认为马井-邡、崇州-郫县、新场-丰谷等地区成蔵条件较好,为I类地区,是川西坳陷须五段页岩气的目标区域。     

Continuous wavelet transforms of spectral decomposition analyses for fluvial reservoir characterization of Miano Gas Field,Indus Platform,Pakistan

Fluvial depositional systems constitute diverse host for the hydrocarbons all over the globe. Nevertheless, predicting the hydrocarbon sands within these assorted sand systems is a challenge for the prospect generation. We apply the continuous wavelet transform of spectral decomposition technique to a 3D seismic data of the Miano Gas Field in the Indus Platform, Pakistan. Full spectrum seismic attributes like the amplitude and root mean square (RMS) detect the reservoir sands down to a restricted reservoir compartment. Nonetheless, the continuous wavelet transforms can be advantageous in imaging and enactment of these clastic reservoirs within the whole reservoir zone. Rock physics reveal high-quality reservoir with an average porosity ～25% together with the discrimination of lithology/fluids, signifying the bright chances for ascertaining the potential stratigraphic reservoirs.     

页岩孔隙研究新进展

随着非常规油气勘探的兴起页岩孔隙研究备受重视,如何研究页岩孔隙已经成为非常规油气首要解决的问题之一,其对页岩油气勘探层位选取、资源潜力评价和油气渗流能力计算具有重要意义。对页岩微—纳米孔隙表征技术、页岩孔隙类别的划分以及页岩孔隙演化规律分别进行了综述并指出存在问题,同时结合最新研究进展对页岩孔隙研究进行展望。提出工业CT—微米CT—纳米CT/FIB系列辐射扫描方法和压汞(MICP)—氮气吸附(N2)—二氧化碳吸附(CO2)流体法是孔隙定量表征的最优方法,通过单井孔隙度测井资料与实验室测定结果建立校正图版指导储层孔隙发育段优选;页岩孔隙分类研究还应该考虑含油气性,利用原子力显微镜等工具加强孔隙含油性研究;孔隙演化规律研究应该采用模拟实验和真实剖面样品对比并结合矿物组成分析等寻找主控因素。     

Contribution of cross time-frequency analysis in assessment of possible relationships between large-scale climatic fluctuations and rainfall of northern central Algeria

This paper is proposed for the investigation of possible relationships between the large-scale atmospheric circulation phenomena such as the North Atlantic Oscillation (NAO), Southern Oscillation (SOI), Mediterranean Oscillation (MO), Western Mediterranean Oscillation (WeMO) and rainfall of Sebaou river watershed (Northern central Algeria), covering a period of 39 years at monthly scale. Several time and scale-based methods were used: correlation and spectral analysis (CSA), continuous wavelet transform (CWT), multiresolution wavelet analysis (MRWA), cross wavelet analysis (XWT), wavelet coherence transform (WCT) and cross multiresolution wavelet analysis (CMRWA). The rainfall analysis by CSA and CWT has been clearly demonstrating the dominance of 1 year and 1–3-year modes, which they explain 30 to 51% and 25 to 28% of the variance respectively. However, the indices have shown that inter-annual fluctuations up to long-term explain between 60 and 90%. CWT and MRWA indicated significant fluctuations materialising a dry period more marked between the 1980s and 1990s with strong trend towards drier conditions starting from the 1980s, explained by the decadal components D7 and the approximation A7. In addition to the annual component, the XWT spectrums reveal strong coefficients for the SOI between 1992–2005 and 1986–2000 for the modes of 5–10 years and higher than 10 years respectively and less intense for NAO. The WCT between NAO and rainfall indicated the most significant relationship for 1 year, 1–3 years and 3–5 years approximately from the early 1980s corresponding to the dry period. However, the SOI affects rainfall only locally and with significant values more or less localised in the time-frequency space between MO, WeMO and rainfall, but this influence could be significant for low-frequency events. CWMRA shows that the components of 5–10 years and higher than 10 years are the most effective to represent climate index-rainfall significant relationships, where change in Daubechies wavelet properties can improve the correlation across the scales. Furthermore, has indicated that the short-term processes dominate the relationship index-rainfall, which masks the long-term phenomena whose influence can sometimes be very distant. As such, the rainfall variability of the study area has shown fairly significant links, at least locally with large-scale atmospheric circulation phenomena.     

用宽频带高分辨率地震分析河道砂体层序地层特征

松辽盆地油气勘探开发的主要目标是大型河流三角洲沉积的河道砂体,河道砂体单层厚度普遍较小,河道改道频繁,地层对比特征不明显,缺乏明显的对比标志。为用地震资料描述河道砂体,近几年我们研制出宽频带高分辨率地震技术,地震频带宽度达5~360 Hz,视主频达150 Hz,分辨率大幅提高。怎样以层序地层的观点用宽频带高分辨率地震描述河道砂体是一项迫切的任务。应用正演模型技术,分析了薄层河道砂体的宽频带高分辨率地震特征,认识到河道砂体两侧河床的角度不整合斜反射是识别河道砂体的重要层序地层标志。本文通过井震结合,解释了松辽盆地杏树岗3D地震工区宽频带高分辨率地震剖面,识别出单一河道和复合河道两种河道类型,分析了扶余油层上部宽频带高分辨率地震的层序地层特征,通过x70井扶余油层层序五下凹型河道砂体的剖面和平面特征分析,依据地震地层学的观点,认为该河道砂体具有网状河三角洲分流河道特征。     

谱模拟方法在高分辨率地震资料处理中的应用

为了克服地震子波的时变影响,避免复杂的时窗大小选取问题,使得谱模拟方法能更好地适应地震信号是平稳信号的假设条件,将改进S变换与谱模拟方法相结合,形成时频域谱模拟方法。在二维时频谱中进行谱模拟处理,该方法能够克服地震子波随地层深度变化的限制。理论模型及实际资料处理效果显示,时频域谱模拟方法能够有效提高地震分辨率,实现地震资料的高分辨处理。     

利用小波相干技术检测致密储层裂缝发育带

目前国内、外油气勘探已经进入岩性油气藏勘探阶段,其中致密碳酸盐岩或页岩油气勘探具有远大前景。这类致密储层中裂缝是油气储集的主要空间。用模拟地震子波的小波函数对原始三维地震数据体作小波变换,可以得到不同频带（分辨率）的地震数据体。分别对具有不同分辨率的三维地震数据体进行C3相干处理,其中低频相干体突出了断裂的信息,而高频相干体则突出反映了受断裂控制下的小断裂或裂缝的发育信息,通过合理的融合系数有选择地对C3相干数据进行融合,获得了能够高精度分辨裂缝发育特征的相干数据体,由此提高了裂缝检测和储层预测的精度。     

Seismic tectono-stratigraphy of fluvio-deltaic to deep marine Miocene silicoclastic hydrocarbon reservoir systems in the Gulf of Hammamet,northeastern Tunisia

Most of hydrocarbon accumulations within the Gulf of Hammamet foreland basins in eastern Tunisia are reservoired within the Upper Miocene Birsa and Saouaf sandstones. It is the case of Birsa, Tazarka, Oudna, Baraka, Maamoura, Cosmos and Yasmine fields. These sandstones constitute oil and gas fields located on folded and faulted horst anticline highs and described as varying from shoreface to shallow marine and typically exhibit excellent reservoir quality of 30 to 35% porosity and good permeability from 500 to 1100 md. In addition, the fracturing of faults enhanced their reservoir quality potential. However, due to the lack of seismic stratigraphic studies to highlight depositional environment reservoir characterization and distribution, petroleum exploration faces structural and stratigraphic trap types and remains on targeting only high fold closures with limited reserve volumes of hydrocarbons. As an example of the Birsa concession case, syn-sedimentary tectonic structuring and geodynamic evolution during Middle to Upper Miocene Birsa reservoir sequences have guided the distribution of depositional environment of sandstone channel systems around horst and grabens by E-W, NE-SW and N-S strike slip flower faults controlling the subsidence distribution combined with the eustatic sea level variations. Seismic sequence stratigraphy study of Miocene Birsa reservoir horizons, based on the analysis and interpretations of E-W and N-S 3D selected regional lines that were compared and correlated to outcrops and calibrated by well data, permitted to highlight the basin configuration and sequence deposit nature and distribution. Sedimentary infilling of the basin from Langhian Ain Ghrab carbonate to Serravallian Tortonian Birsa and Saouaf sandstone and shale formations is organized in four third-order seismic sequences, limited by regional erosional toplap, onlap and downlap unconformity surfaces and by remarkable chronostratigraphic horizons of forced and normal erosive lowstand and highstand system tracts separated by transgressive and maximum flooding surfaces. Reconstructed sedimentary paleo-environment distribution vary from deltaic fluvial proximal deposits in the northern part of the high central Birsa horst to a delta front and prodelta coastal and shelf shore face and shore line channelized deposits in the surrounding borders of grabens. Distal deposits seem to be distributed from upper to lower slope fans and probably to the basin floor on the flanks of the subsiding grabens. Synthetic predictive paleogeographic depositional reservoir fairway map distribution of Lower, Middle and Upper Birsa sandstone reservoirs highlights four main domains of channelized superposed and shifted reservoirs to explore.     

Petrophysical,seismic structural and facies analysis of the Miocene reservoirs of East Morgan oil field,Gulf of Suez,Egypt

The Gulf of Suez is characterized by the presence of many hydrocarbon-bearing fields including reservoirs ranging in age from the Palaeozoic to the Tertiary. East Morgan oil field is one of the promising oil fields which are located in the southern part of the Gulf of Suez and tapping hydrocarbon deposits and potentials of the Miocene age. The purpose of this work is to evaluate the Miocene sediments of the Asl and Hawara Formations in East Morgan oil field (western sub-basin) through carrying out an integrated petrophysical, seismic structural and sequence stratigraphy study. Quantitative well logging analyses are carried out over Asl and Hawara Formations to throw light over their hydrocarbon potentiality. Good oil saturation is exhibited by the sand sections of Asl Formation, and fair to good are assigned for those of Hawara Formation in the Belayim dip province. On the other hand, a little hydrocarbon saturation is represented by both formations to the south of the study area in the Morgan accommodation zone (MAZ). The estimated petrophysical parameters of Asl reservoir throughout the study area range between 4 % and 10 % for effective porosity, 18 % and 89 % for shale volume and 2 % and 48 % for hydrocarbon saturation. Meanwhile, the ranges of 1–8 %, 20–98 % and 2–32 % are given for Hawara Formation for effective porosity, shale volume and hydrocarbon saturation, respectively. The lateral distribution maps show that the central and the western parts of the MAZ attain the best petrophysical parameters and hydrocarbon potentiality. Seismic facies analysis, structural framework and depositional history of the study area were studied through interpreting the seismic reflection data of 27 seismic profiles. A number of geo-seismic cross sections are constructed and interpreted to investigate the structural setting of the study area and clarify the main structural elements that affect the hydrocarbon bearing reservoirs. A group of simple NW–SE step-like normal faults, parallel to the Clysmic trend, is found cutting through the reservoir rocks at the bottom layers of the section (Rudeis Formation) and extending upwards to overlying layers (Zeit Formation). Some graben- and horst-shaped structures are found and usually bounded by two sets of oppositely dipping normal step-like cross faults. The seismic facies and sequence analysis revealed that the Miocene rocks are subdivided into two major third-order depositional sequences (S1 and S2), separated by two major depositional sequence boundaries (DSB1 and DSB2). The first sequence (S1, Lower–Middle Miocene rocks) is of prime interest, as it encounters the main hydrocarbon reservoirs in the study area (Asl and Hawara Formations that are equivalent to Rudeis Formation). The seismic facies of this sequence are characterized by low to moderate amplitude, discontinuous horizons and bounded by the depositional sequence boundary (DSB1) at the top. The reflection geometry at the cycle boundaries is considered as erosional truncation, toplaps and even concordant along the upper boundary of the cycle. The external form of these sediments is considered as sheet-like and wedge-shaped units. The entrapment of hydrocarbons seems to be of a combined effect of the stratigraphic and structural elements. It appears clear that both of the step-like structural fault system and the lateral variation of facies are the key parameters that control the accumulation of hydrocarbon in this area and in East Morgan field as a whole.     

Source parameters of some recent earthquakes in the Gulf of Aqaba, Egypt

Gulf of Aqaba is recognized as an active seismic zone where many destructive earthquakes have occurred. The estimation of source parameters and coda Q attenuation are the main target of this work. Fifty digital seismic events in eight short-period seismic stations with magnitude 2.5–5.2 are used. Most of these events occurred at hypocentral depths in the range of 7–20 km, indicating that the activity was restricted in the upper crust. Seismic moment, M _o, source radius, r, and stress drop, Δσ, are estimated from P- and S-wave spectra using the Brune’s seismic source model. The average seismic moment generated by the whole sequence of events was estimated to be 4.6E?+?22 dyne/cm. The earthquakes with higher stress drop occur at 10-km depth. The scaling relation between the seismic moment and the stress drop indicates a tendency of increasing seismic moment with stress drop. The seismic moment increases with increasing the source radius. Coda waves are sensitive to changes in the subsurface due to the wide scattering effects generating these waves. Single scattering model of local earthquakes is used to the coda Q calculation. The coda with lapse times 10, 20, and 30 s at six central frequencies 1.5, 3, 6, 12, 18, 24 Hz are calculated. The Q _c values are frequency dependent in the range 1–25 Hz, and are approximated by a least squares fit to the power law [ $ {Q_c}(f) = {Q_o}{(f/{f_o})^\eta } $ ]. The average of Q _c values increases from 53?±?10 at 1.5 Hz to 700?±?120 at 24 Hz. The average of Q _o values ranges from 13?±?1 at 1.5 Hz to 39?±?4 at 24 Hz. The frequency exponent parameter η ranges between 1.3?±?0.008 and 0.9?±?0.001.     

页岩气资源潜力与勘探开发前景

页岩气为近年来在北美地区广泛勘探开发的天然气新目标,在全球非常规油气勘探开发中异军突起,成为突破最晚、近期发展最快的非常规天然气资源。依据北美地区页岩气勘探开发的历程和全球页岩气勘探开发的进展,阐述了全球页岩气勘探开发的基本态势和页岩气5个方面的典型特征,分析了全球页岩气的资源潜力与分布特征,预测中国页岩气资源潜力约100×1012m3,指出页岩气的成功勘探开发是近10年来油气地质理论与工程技术取得的最激动人心的重大成就,页岩气资源潜力丰富,实现全面开发将带来一场全球的能源革命。最后,提出了4点加快中国页岩气发展的建议。     

Geophysical characteristics of Wadi Hanifah water system, Riyadh, Saudi Arabia

Integrated geophysical techniques including resistivity image, vertical electrical sounding (VES), and seismic refraction have been conducted to investigate the Wadi Hanifah water system. The groundwater in Wadi Hanifah has problems caused by the high volumes of sewage water percolating into the ground. The combination of VES, resistivity image, and seismic refraction has made a valuable contribution to the identification of the interface between the contaminated and fresh water in Wadi Hanifah area. The contaminated groundwater has lower resistivity values than fresh groundwater due to the higher concentration of ions which reduces the resistivity. Resistivity image and sounding in this area clearly identified the nature of the lithological depth and proved useful at identifying water-bearing zones. Fresh groundwater was found in the study area at a depth of 100 m within the fractured limestone. Water-bearing zones occur in two aquifers, shallow contaminated water at 10 m depth in alluvial deposits and the deeper fresh water aquifer at a depth of about 100 m in fractured limestone. The interface between the contaminated water (sanitary water) and fresh water marked out horizontally at 100 m distance from the main channel and vertically at 20 m depth.