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1.
Bin Min Liangshu Shu Huibin Yin Weijiang Xin Dirong Zhang 《Marine and Petroleum Geology》2007,24(10):579-590
Several subaqueous alluvial fans are developed along the footwall of the northern boundary fault zone—the Daxing fault of the Langgu sag, Bohai Bay Basin, North China. A distinct feature is the significant difference in hydrocarbon enrichment between neighboring wells drilled in the same sedimentary facies. This paper analyses the controlling factors for hydrocarbon accumulation of subaqueous alluvial fan in the Caiyu field, north of the Langgu sag. Based on reprocessed seismic data and using Jason inversion method, the contrast of cross-well correlation panel was established and a reservoir type model was build-up; reservoir heterogeneity was interpreted from inversion impedance data. The result shows six conglomeratic bodies in this fan, which are stacked vertically and laterally. The lithofacies is the key controlling factor for the hydrocarbon accumulation, and diagenesis and tectonic stresses also play important roles in the hydrocarbon enrichment. 相似文献
2.
An analysis of 3D seismic data from the northwestern part of the Ulleung Basin, East Sea, revealed that the gas hydrate stability zone (GHSZ) consists of five seismic units separated by regional reflectors. An anticline is present that documents activity of many faults. The seismic indicators of gas hydrate occurrence included bottom simulating reflector (BSR) and acoustic blanking in the gas hydrate occurrence zone (GHOZ). By the analysis of the seismic characteristics and the gradient of the sedimentary strata, the GHOZ was divided into four classes: (1) dipping strata upon strong BSR, (2) dipping strata below strong BSR, (3) parallel strata with acoustic blanking, and (4) parallel strata below weak BSR. Seismic attributes such as reflection strength and instantaneous frequency were computed along the GHOZ. Low reflection strength and high instantaneous frequency were identified above the BSR, indicating the occurrence of gas hydrate. A remarkably high reflection strength and low instantaneous frequency indicated the presence of free gas below the BSR. Considering the distribution of the gas hydrate and free gas, two gas migration processes are suggested: (1) stratigraphic migration through the dipping, permeable strata and (2) structural migration from below the GHSZ along faults. 相似文献
3.
The bottom simulating reflector (BSR), the boundary between the gas hydrate and the free gas zone, is considered to be the most common evidence in seismic data analysis for gas hydrate exploration. Multiple seismic attribute analyses of reflectivity and acoustic impedance from the post-stack deconvolution and complex analysis of instantaneous attribute properties including the amplitude envelope, instantaneous frequency, phase, and first derivative of the amplitude of seismic data have been used to effectively confirm the existence of a BSR as the base of gas hydrate stability zone. In this paper, we consider individual seismic attribute analysis and integrate the results of those attributes to locate the position of the BSR. The outputs from conventional seismic data processing of the gas hydrate data set in the Ulleung Basin were used as inputs for multiple analyses. Applying multiple attribute analyses to the individual seismic traces showed that the identical anomalies found in two-way travel time (TWT) between 3.1 and 3.2 s from the results of complex analyses and l 1 norm deconvolution indicated the location of the BSR. 相似文献
4.
按河道形态,河流分为４类：（１）顺直河;（２）曲流河;（３）辫状河;（４）网状河。根据河道砂岩体主体的宽（ｗ）与（ｈ）高之比,河道砂岩体分为带状砂岩体（ｗ∶ｈ小于１５）和席状砂岩体（ｗ∶ｈ大于１５）。在参考前人资料的基础上,总结了在横切河道的地震剖面上河道砂岩体的反射形态、结构及振幅变化。重点介绍了曲流河内侧沙洲地震勘探,以及三维地震勘探技术在寻找河道砂岩体方面的应用。并强调指出,在河道砂岩体地震勘探中,应当加强地震资料与钻井资料、测井资料的结合。 相似文献
5.
During the exploration of stratigraphic reservoirs, the key to locating these reservoirs is to identify the sandstone distribution. Seismic data can be used to recognize large-scale distributary-channel sedimentary bodies; however, depiction of sedimentary bodies in small distributary channels using traditional interpretation data from seismic profiles is extremely difficult. In the Upper Cretaceous first sandstone bed of the third member of the Nenjiang Formation (called the Nen 3 member for simplicity) in the XB area of the southern Songliao basin, distributary channels are the main sedimentary facies. The distributary channels migrate frequently; therefore, it is difficult to precisely depict the morphology of the channel and the distribution of sandstone. In this study, we investigated the deposition of distributary channels using equal-scale formation plane seismic attributes such as post-stack amplitude, instantaneous amplitude and seismic waveform classification, analyzed well logging data from target formations, and mapped the distribution of distributary channels. This study shows that seismic sedimentological study and stacking multiple attribute analysis can identify the distribution of distributary channels precisely and effectively. The attributes of equal-scale strata slices are evidently superior to those of time and horizon slices; Attribute extraction and selection of equal-scale formation slices is an essential step. The comprehensive selection of seismic attributes that show a good correlation to a single-well can be used to clearly depict channel bodies. The overlap of the 40-Hz single-frequency energy and the RMS amplitude depicts the sedimentary characteristics and shapes of sandstone bodies in main channels as well as small-scale distributary channels more clearly than a single attribute. These attributes show that the first sandstone bed of the Nen 3 member was from distributary channels with complex shapes. The distributary channels cut across each other vertically and laterally. It indicates that, during the deposition of the Nen 3 member in XB area, the direction of the main channel is from north to south, and the provenance could be from north and east. The method of this paper may provide some helpful suggestions to the geologist using seismic attributes to undertake research on sedimentary environment at other places in the world. 相似文献
6.
The Cengio sandstone member of the Tertiary Piedmont Basin in northwestern Italy has a conservatively estimated volume of
2.5 to 3 km3 (length: 6.4 km; width: 4.8 km; thickness: 170 m). It is interpreted as a sandstone-rich submarine fan deposit. The Cengio
member consists of eight tabular depositional sandstone lobes that are 5- to 25-m thick. These lobes filled a submarine structural
depression and onlap and/or pinch-out against bounding slope mudstones. The stacking of the lobe units was related to synsedimentary
tectonism.
Margin setting represents fan and/or source area 相似文献
7.
Abstract Keeping in view the paucity of information as to the nature of the marine sediments from the continental shelf adjoining the Indian subcontinent, a number of shallow seismic surveys were carried out, nearshore and offshore Bombay between 18°45'N and 21°00'N. Representative core samples preserving their natural state were also retrieved from the region in the water depths ranging from 5 to 70 m for the determination of physical properties in the laboratory. Data on the physical, acoustic, and elastic properties of the sediment cores are reported for the first time. Useful individual least‐squares relations are presented for acoustic impedance, reflection coefficient, and bulk modulus against density; for the dependence of rigidity and bulk moduli on the constrained modulus; for the association between impedance and field sediment velocity against P‐velocity; and for rigidity against Poisson's ratio. Results indicate that the bulk modulus and Young's modulus are higher for silty clay and clayey silt samples than for the clay samples. Similarly, the acoustic impedance, reflection coefficient, and constrained modulus of silty clay and clayey silt are also higher than clay. The results are found to be comparable to the North Atlantic and Bay of Bengal sediments. 相似文献
8.
琼东南盆地深水区新近系海底扇沉积特征与资源潜力 总被引：1，自引：1，他引：0
综合利用钻井、岩心、薄片及分析化验资料研究了琼东南盆地深水区新近系海底扇沉积特征,并利用最新的三维地震资料,通过井震精细标定、多属性融合技术、方差体切片、三维地貌砂体镂空等综合技术手段,精细刻画了海底扇砂体的空间分布特征。研究结果表明,深水区新近系海底扇是由陆架区的砂体滑塌并二次搬运形成,形成过程具有多期次性。受不同物源的影响,海底扇岩性和物性存在较大的差异。海底扇岩性及沉积构造具有砂质滑塌、碎屑流、浊流和深水底流改造的特征。海底扇的沉积微相、厚度、砂泥比和砂泥岩空间配置关系直接控制了地震振幅反射强度和频率的变化。砂体纵向叠置,横向连片,并被后期泥质水道切割分块形成多个岩性圈闭。综合分析认为,深水区海底扇砂体发育区烃源条件优越,储盖配置关系和圈闭条件良好,具备形成大中型岩性油气藏的有利条件,具有较大的油气勘探潜力。 相似文献
9.
In the Shenhu area of the northern South China Sea (SCS), canyon systems and focused fluid flow systems increase the complexity of the gas hydrate distribution in the region. It also induces difficulties in predicting the hydrate reservoir characteristics and quantitatively evaluating reservoir parameters. In this study, several inversion methods have been executed to estimate the velocities of strata and gas hydrate concentrations along a profile in the Shenhu area. The seismic data were inverted to obtain the reflection coefficient of each stratum via a spectral inversion method. Stratigraphic horizons were then delineated by tracking the inverted reflectivities. Based on the results of spectral inversion, a low-frequency velocity field of the strata was constructed for acoustic impedance inversion. Using a new iterative algorithm for acoustic impedance inversion, reflection coefficients were converted into velocities, and the velocity variations of the strata along a 2D seismic line were then obtained. Subsequently, gas hydrate saturations at well SH2 were estimated via the shale-corrected resistivity method, the chloride ion concentration method and three different rock physics models. The results were then compared to determine the optimal rock physics model, and the modified Wood equation (MWE) was found to be appropriate for this area. Finally, the inverted velocities and MWE were used to predict the distribution and concentrations of gas hydrates along the seismic line. The estimated spatial distribution of gas hydrates is consistent with that from sonic logging and resistivity data at well SH2, and with the drilling results. Therefore, this method is applicable in areas with no well data, or with few wells, and provides an effective tool for predicting and evaluating gas hydrates using seismic data. 相似文献
10.
Shiguo Wu Xiujuan Wang How Kin Wong Guangxue Zhang 《Marine Geophysical Researches》2007,28(2):127-138
The passive northern continental margin of the South China Sea is rich in gas hydrates, as inferred from the occurrence of
bottom-simulating reflectors (BSR) and from well logging data at Ocean Drilling Program (ODP) drill sites. Nonetheless, BSRs
on new 2D multichannel seismic reflection data from the area around the Dongsha Islands (the Dongsha Rise) are not ubiquitous.
They are confined to complex diapiric structures and active fault zones located between the Dongsha Rise and the surrounding
depressions, implying that gas hydrate occurrence is likewise limited to these areas. Most of the BSRs have low amplitude
and are therefore not clearly recognizable. Acoustic impedance provides information on rock properties and has been used to
estimate gas hydrate concentration. Gas hydrate-bearing sediments have acoustic impedance that is higher than that of the
surrounding sediments devoid of hydrates. Based on well logging data, the relationship between acoustic impedance and porosity
can be obtained by a linear regression, and the degree of gas hydrate saturation can be determined using Archie’s equation.
By applying these methods to multichannel seismic data and well logging data from the northern South China Sea, the gas hydrate
concentration is found to be 3–25% of the pore space at ODP Site 1148 depending on sub-surface depth, and is estimated to
be less than values of 5% estimated along seismic profile 0101. Our results suggest that saturation of gas hydrate in the
northern South China Sea is higher than that estimated from well resistivity log data in the gas hydrate stability zone, but
that free gas is scarce beneath this zone. It is probably the scarcity of free gas that is responsible for the low amplitudes
of the BSRs. 相似文献
11.
目前琼东南盆地北礁凹陷中中新统梅山组顶部丘形反射引起广泛关注,但对其成因有不同认识。本文通过高精度二维、三维地震、钻井资料,研究丘形反射的特征。研究表明北礁地区梅山组顶部发育近东西向展布的长条形丘体,丘间为水道,丘内为中-弱振幅的地震反射,与西南部强振幅水道砂岩形成鲜明的对比,波阻抗反演揭示丘内为低波阻抗,属泥岩范畴。梅山组塑性丘内地层发生重力扩展,在其上覆的脆性地层（强振幅砂岩和弱振幅泥岩）发育多边形断层,反推出梅山组形成于深水环境,丘为泥丘,沉积环境分析也认为北礁凹陷中中新世为半深海沉积,梅山组的丘-谷分别对应上覆地层的谷-丘,认为是底流剥蚀/沉积成因。本文的研究对南海北部丘形反射的认识有重要意义,并可降低油气探勘风险。 相似文献
12.
Three-dimensional (3D) seismic data acquired for hydrocarbon exploration reveal that gas accumulations are common within the
2–3 km thick Plio-Pleistocene stratigraphic column of the south-western Barents Sea continental margin. The 3D seismic data
have relatively low-frequency content (<40 Hz) but, due to dense spatial sampling, long source-receiver offsets, 3D migration
and advanced interpretation techniques, they provide surprisingly detailed images of inferred gas accumulations and the sedimentary
environments in which they occur. The presence of gas is inferred from seismic reflection segments with anomalously high amplitude
and reversed phase, compared with the seafloor reflection, so-called bright spots. Fluid migration is inferred from vertical
zones of acoustic masking and acoustic pipes. The 3D seismic volume allows a spatial analysis of amplitude anomalies inferred to reflect the presence of gas and fluids. At several locations, seismic attribute
maps reveal detailed images of flat spots, inferred to represent gas–water interfaces. The data indicate a focused fluid migration
system, where sub-vertical faults and zones of highly fractured sediments are conduits for the migration of gas-bearing fluids
in Plio-Pleistocene sediments. Gas is interpreted to appear in high-porosity fan-shaped sediment lobes, channel and delta
deposits, glacigenic debris flows and sediment blocks, probably sealed by low-permeability, clayey till and/or (glacio)marine
sediments. Gas and fluid flow are here attributed mainly to rapid Plio-Pleistocene sedimentation that loaded large amounts
of sedimentary material over lower-density, fine-grained Eocene oozes. This probably caused pore-fluid dewatering of the high-fluid
content oozes through a network of polygonal faults. The study area is suggested to have experienced cycles of fluid expulsion
and hydrocarbon migration associated with glacial–interglacial cycles. 相似文献
13.
辽东湾南部下第三系地震地层学研究 总被引：1，自引：0，他引：1
本文依据地震地层学原理,结合层速度和砂岩百分比的研究,描述了辽东湾南部下第三系地震相和沉积相类型及特征,确定出近岸水下扇沉积体系、三角洲—滑塌浊积扇沉积体系、滨浅湖—滩坝沉积体系和深湖—深水浊积扇沉积体系,指出这些沉积体系的平面分布具有不对称性,垂向演化具有继承性和新生性的特点。最后预测了有利勘探地区。 相似文献
14.
The Cengio sandstone member of the Tertiary Piedmont Basin in northwestern Italy has a conservatively estimated volume of 2.5 to 3 km3 (length: 6.4 km; width: 4.8 km; thickness: 170 m). It is interpreted as a sandstone-rich submarine fan deposit. The Cengio member consists of eight tabular depositional sandstone lobes that are 5- to 25-m thick. These lobes filled a submarine structural depression and onlap and/or pinch-out against bounding slope mudstones. The stacking of the lobe units was related to synsedimentary tectonism. 相似文献
15.
大量研究表明南海北部珠江口盆地是天然气水合物发育区,但是该盆地东部揭阳凹陷水合物研究较少。本文利用揭阳凹陷新采集三维地震资料,对该三维地震资料进行成像道集优化和叠前时间偏移处理,得到针对水合物的新处理地震数据体,并通过高精度网格层析反演得到层速度数据体。利用该数据开展叠后约束稀疏脉冲反演,获得含天然气水合物地层波阻抗异常,综合分析反演与地震属性识别水合物。从新处理地震资料看,该区域似海底反射(bottom simulation reflection,BSR)反射呈连续、不连续与地层斜交等特征,BSR发育在一个继承性小型水道上,且下部断裂和气烟囱发育。通过分析BSR特征及BSR上下地层的速度、波阻抗、振幅、频率、相干等属性异常,结合水合物成藏条件,发现了南海北部新的天然气水合物有利富集区,为该区域水合物勘探提供基础。 相似文献
16.
浅剖和单道地震是大范围研究新近纪以来沉积特征的主要技术方法,由于地震资料分辨率的限制,往往只能划分大的沉积单元,不能识别亚相、微相等,而地震资料的瞬时属性可以更加精细地刻画地层信息。基于2013年在南黄海陆架获得的单道地震资料,对南黄海中西部海域第四系进行了分析,并利用单道资料的三瞬属性对地层进行地震地层单元划分、沉积环境分析,总结出该区域不同沉积相的三瞬波阻特征。研究结果表明,在测线的Qc2钻孔位置处,根据三瞬属性在海底以下74.64m深度内划分了7个地震地层沉积单元,并划分出多个亚相。它所反映的沉积相与该区已知Qc2钻孔的地层对应度较高。瞬时相位较为清楚的显示地下地层的接触情况,更好地展示了地震层序在空间上的关系,解决了该测线在常规地震剖面上无法清晰、精细识别沉积相的问题。三瞬属性的应用可以在缺少钻井资料时提高在地震资料剖面划分地层、识别接触面的能力,为大陆架科学钻探项目中未知井位选址提供参考。 相似文献
17.
Gas hydrate saturation from acoustic impedance and resistivity logs in the Shenhu area, South China Sea 总被引：4，自引：0，他引：4
Xiujuan Wang Shiguo Wu Myung LeeYiqun Guo Shengxiong YangJinqiang Liang 《Marine and Petroleum Geology》2011,28(9):1625-1633
During the China’s first gas hydrate drilling expedition -1 (GMGS-1), gas hydrate was discovered in layers ranging from 10 to 25 m above the base of gas hydrate stability zone in the Shenhu area, South China Sea. Water chemistry, electrical resistivity logs, and acoustic impedance were used to estimate gas hydrate saturations. Gas hydrate saturations estimated from the chloride concentrations range from 0 to 43% of the pore space. The higher gas hydrate saturations were present in the depth from 152 to 177 m at site SH7 and from 190 to 225 m at site SH2, respectively. Gas hydrate saturations estimated from the resistivity using Archie equation have similar trends to those from chloride concentrations. To examine the variability of gas hydrate saturations away from the wells, acoustic impedances calculated from the 3 D seismic data using constrained sparse inversion method were used. Well logs acquired at site SH7 were incorporated into the inversion by establishing a relation between the water-filled porosity, calculated using gas hydrate saturations estimated from the resistivity logs, and the acoustic impedance, calculated from density and velocity logs. Gas hydrate saturations estimated from acoustic impedance of seismic data are ∼10-23% of the pore space and are comparable to those estimated from the well logs. The uncertainties in estimated gas hydrate saturations from seismic acoustic impedances were mainly from uncertainties associated with inverted acoustic impedance, the empirical relation between the water-filled porosities and acoustic impedances, and assumed background resistivity. 相似文献
18.
《Marine and Petroleum Geology》2007,24(6-9):504-514
Forward seismic models of two ‘seismic scale’ outcrops of different style channel systems have been made to investigate their seismic signature. These two outcrops illustrate the geometric end members of channel stacking architecture in response to low- and high-accommodation space. The Eocene Nohut Tepe channel system of the Elaziğ Basin in eastern Turkey was deposited in an area of high accommodation resulting in an aggradational geometrical offset stacking of channels up against a slope. The Eocene Ainsa II Channel system of the Tremp-Pamplona Basin in the Spanish Pyrenees was deposited in an area of low accommodation resulting in a tabular, compound sheet geometry, with amalgamated channel bodies separated by clay drapes.Depth models were drawn from outcrop photos and converted to impedance models by assigning acoustic impedance properties to the sand filled channels and surrounding and interbedded mud and clay layers. These were the input for the forward seismic models, which constructed various frequency synthetic seismic sections of the two outcrops. Analysis of the outcrop synthetic seismic identified three distinct reflection configurations. Type I is characterised by a strong black peak and white trough reflection, which is due to a discrete channel body. Type II is characterised by multiple offset, time ‘stepped’ black peak reflections that are underlain by one continuous, strong white trough reflection, which is due to offset stacked channel bodies. Type III is characterised by strong black peaks which onlap an underlying, continuous white trough reflection, caused by the lateral amalgamation of channel bodies.These three types of reflection configurations observed on the outcrop synthetic seismic can also be found on actual seismic from channelised turbidite systems, which aids in interpreting channel stacking architecture, accommodation space prediction and depositional styles from the actual seismic data. Channel stacking architecture is clearly an important aspect which needs to be considered when making channel system interpretations based on seismic data. 相似文献
19.
The Melut Basin is a rift basin in the interior Sudan linked to the Mesozoic-Cenozoic Central and Western African Rift System. The Paleocene Yabus Formation is the main reservoir deposited in heterogeneous fluvial/lacustrine environment. Delineation of channel sandstone from shale is a challenge in reservoir exploration and development. We demonstrate a detailed 3D quantitative seismic interpretation approach that integrates petrophysical properties derived from well logs analysis. A porosity transform of acoustic impedance inversion provided a link between elastic and rock properties. Thus, we used seismic porosity to discriminate between different facies with appropriate validation by well logs. At the basin scale, the results revealed lateral and vertical facies heterogeneity in the Melut Basin. Good reservoir quality is observed in the Paleocene Yabus Formation. The sand facies indicated high porosity (20%) corresponding to low acoustic impedance (20000–24000 g ft/(cm3.s)). However, lower quality reservoir is observed in the Cretaceous Melut Formation. The porosity of sand/shale facies is low (5%), corresponding to high acoustic impedance (29000–34000 g ft/(cm3.s)). This suggests that the Yabus Sandstone is potentially forming a better reservoir quality than Melut Formation. At the reservoir scale, we evaluated the facies quality of Yabus Formation subsequences using petrophysical analysis. The subsequences YB1 to YB3, YB4 to YB7 and YB8 to YB10 showed relatively similar linear regressions, respectively. The subsequence of YB4 to YB7 is considered the best reservoir with higher porosity (25%). However, subsequence YB1 to YB3 showed lower reservoir quality with higher shale volume (30%). This attributed to floodplain shale deposits in this subsequence. Similarly, the high porosity (20%) recognized in deeper subsequences YB6 to YB9 is due to clean sand facies. We learnt a lesson that appropriate seismic preconditioning, exhaustive petrophysical analysis and well log validation are important keys for improved reservoir quality prediction results in fluvial/lacustrine basins. 相似文献
20.
Shuo Chen Renhai Pu Huiqiong Li Hongjun Qu Tianyu Ji Siyu Su Yunwen Guan Hui Zhang 《海洋学报(英文版)》2022,41(9):86-106
The Dongfang1-1 gas field (DF1-1) in the Yinggehai Basin is currently the largest offshore self-developed gas field in China and is rich in oil and gas resources. The second member of the Pliocene Yinggehai Formation (YGHF) is the main gas-producing formation and is composed of various sedimentary types; however, a clear understanding of the sedimentary types and development patterns is lacking. Here, typical lithofacies, logging facies and seismic facies types and characteristics of the YGHF are identified based on high-precision 3D seismic data combined with drilling, logging, analysis and testing data. Based on 3D seismic interpretation and attribute analysis, the origin of high-amplitude reflections is clarified, and the main types and evolution characteristics of sedimentary facies are identified. Taking gas formation upper II (IIU) as an example, the plane distribution of the delta front and bottom current channel is determined; finally, a comprehensive sedimentary model of the YGHF second member is established. This second member is a shallowly buried “bright spot” gas reservoir with weak compaction. The velocity of sandstone is slightly lower than that of mudstone, and the reflection has medium amplitude when there is no gas. The velocity of sandstone decreases considerably after gas accumulation, resulting in an increase in the wave impedance difference and high-amplitude (bright spot) reflection between sandstone and mudstone; the range of high amplitudes is consistent with that of gas-bearing traps. The distribution of gas reservoirs is obviously controlled by dome-shaped diapir structural traps, and diapir faults are channels through which natural gas from underlying Miocene source rocks can enter traps. The study area is a delta front deposit developed on a shallow sea shelf. The lithologies of the reservoir are mainly composed of very fine sand and coarse silt, and a variety of sedimentary structural types reflect a shallow sea delta environment; upward thickening funnel type, strong toothed bell type and toothed funnel type logging facies are developed. In total, 4 stages of delta front sand bodies (corresponding to progradational reflection seismic facies) derived from the Red River and Blue River in Vietnam have developed in the second member of the YGHF; these sand bodies are dated to 1.5 Ma and correspond to four gas formations. During sedimentation, many bottom current channels (corresponding to channel fill seismic facies) formed, which interacted with the superposed progradational reflections. When the provenance supply was strong in the northwest, the area was dominated by a large set of delta front deposits. In the period of relative sea level rise, surface bottom currents parallel to the coastline were dominant, and undercutting erosion was obvious, forming multistage superimposed erosion troughs. Three large bottom current channels that developed in the late sedimentary period of gas formation IIU are the most typical. 相似文献