Seismic acquisition guided by the compressive sensing theory can significantly improve seismic data acquisition efficiency and reduce the cost. After reviewing the basic principles of compressive sensing, we propose an optimized random sampling method that can control the maximum sampling interval and improve the design flexibility. We analyze several factors that can introduce reconstruction errors from compressive sensed data and learn that besides sampling method, reconstruction errors increase with decimation degree and the complexity of structures and also depend on the reconstruction workflow. In addition, we provide a basic workflow of the geometry design of compressive sensing acquisition. We analyze the feasibility of the three types of receiving equipment that are widely used in marine environment and discuss the potential cost reduction and efficiency gain. Our field example demonstrates the detailed working process and the feasibility of the combination of random sailing line intervals and random shot intervals and verifies the effect of cost saving and efficiency increasing.

In the Gulf of Mexico and adjacent landmasses, faults are very complex, and their distribution is closely related to plate tectonics, ocean-land boundary, and former structure. The plane position of the faults can be identified by the maximum characteristic of the vertical derivative of the normalized vertical derivative of the total horizontal derivative (NVDR-THDR) of the Bouguer gravity anomaly. The apparent depth of the faults is inverted by the Bouguer gravity anomaly curvature property. Based on tectonic evolutionary processes and the plane distribution and apparent depth characteristics of the faults, a complete fault system for the Gulf of Mexico and adjacent areas has been established, including 102 faults. The apparent depths of 33 first-class faults are 16-20 km and for 69 second-class faults are 12-16 km. The F1-2 and F1-3 subduction fault zones are two caused by the subduction of the Cocos Plate into the old Yucatan and Chorti landmasses; F1-11 and F1-12 fault zones extend westward to the coast of Guatemala and do not extend into the continent; F1-17 and F1-20 faults, which control the boundary of the oceanic crust, do not extend southward into the continent. The fault system, which radiates in a "fan-shaped" structure as a whole, unfolds to the northeast. Faults of different nature and sizes are distributed in the Cocos Plate subduction zone, Continental, Gulf of Mexico, Yucatan old landmass and Caribbean Plate in NW, NNW, NS, NE and NEE directions. In the Gulf of Mexico region, the fault system is a comprehensive reflection of former tectonic movements, such as plate movement, drift of old landmasses and expansion of oceanic crusts. The first-class faults control the plate and ocean-continental boundaries. The second-class faults are subordinate to the first-class faults or related to the distribution of different sedimentary layers.

In the study of Gulf of Mexico and its adjacent areas, the faults are kinds of important structures in the plate tectonics, oceanic-continental distribution and sedimentary basin structure. Based on the normalized vertical derivative of total horizontal derivative (NVDR-THDR) of Bouguer gravity anomaly and the minimum curvature field separation method, the distribution characteristics of the faults and the relating geological effects are studied. Because of the interaction between the plates, at the plate margin, the maximum values in the map of NVDR-THDR of Bouguer gravity anomaly are characterized by stable and continuous strikes. The maximum values in the map of NVDR-THDR of Bouguer gravity anomaly of intraplate region are macroscopically consistent and locally discontinuous. The faults in NWW and EW-NEE directions are mostly related to plate movement. In NE-NEE directions, arc faults are related to oceanic crust expansion. The faults in NE and NW are related to late Jurassic rift activities, or simply showing the boundaries of Yucatan and Chortis old landmass. The faults in nearly SN direction are less than that of we have talked above. In the Gulf of Mexico, there are four kinds of faults: the transition faults and mid-ocean ridge faults in the middle of central deep-sea area, the ocean-crust boundary faults in the north and south side of the central deep-sea area, the faults of thinning continental crust in the north and south of the Gulf of Mexico and the strike slip faults in the west of the Gulf of Mexico. Our research can contribute to regional geological researches and natural resources evaluations.

弹性波高斯束偏移是一种兼顾成像精度与计算效率的多分量地震成像方法,但当前的研究多集中在各向同性介质声波、弹性波成像和各向异性介质声波成像,针对各向异性介质弹性波偏移的文献相对较少.为此,在前人的研究基础上,发展了各向异性介质弹性波射线追踪方程,以二维各向异性弹性波Kirchhoff-Helm-holtz积分为基础,利用弹性动力学表征的格林张量推导了各向异性介质中弹性波波场正、反向延拓公式,提出了一种针对各向异性介质多分量地震数据的成像方法.通过在成像公式中引入权函数,很好地压制各向异性介质成像中不同波型引起的串扰.通过引入符号函数,解决了转换波成像过程中的极性反转问题.TTI介质洼陷模型和TTI介质多层构造模型试算结果表明:与各向同性介质弹性波高斯束偏移方法相比,各向异性介质弹性波高斯束偏移成像结果的信噪比较高、同相轴连续性较好、构造位置更准确;使用多分量地震记录,利用纵、横波波场信息成像,有效提高了成像分辨率;与传统的基于标量波场的成像方法相比,所提方法的适应性更好.

PreviousNext No AccessInternational Workshop on Gravity, Electrical & Magnetic Methods and Their Applications, Xi'an, China, 19–22 May 2019Calculation of the subsalt gravity anomaly based on the minimum curvature technique for potential field data separationAuthors: Xiaolin JiWanyin WangXiangdong DuXuliang FengXiaolin JiChang'an University, School of Geology Engineering and Geomatics, Institute of Gravity and Magnetic Technology, Xi'an, Shaanxi, ChinaSearch for more papers by this author, Wanyin WangChang'an University, School of Geology Engineering and Geomatics, Institute of Gravity and Magnetic Technology, Xi'an, Shaanxi, ChinaSearch for more papers by this author, Xiangdong DuCNOOC Research Institute, Beijing, ChinaSearch for more papers by this author, and Xuliang FengChang'an University, School of Geology Engineering and Geomatics, Institute of Gravity and Magnetic Technology, Xi'an, Shaanxi, ChinaSearch for more papers by this authorhttps://doi.org/10.1190/GEM2019-023.1 SectionsAboutPDF/ePub ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareFacebookTwitterLinked InRedditEmail Abstract We present a method to separate the subsalt gravity anomaly from the Bouguer gravity anomaly using the minimum curvature technique for potential field data separation. The theoretical model tests shows the minimum curvature technique can separate the gravity anomaly of the isolated field source. Using this method, we calculated the subsalt gravity anomaly of the salt basin in the central and southern parts of West Africa. This subsalt anomaly provides basic data for reinterpretation of the subsalt seismic sequence in this area. Keywords: separation, gravity, saltPermalink: https://doi.org/10.1190/GEM2019-023.1FiguresReferencesRelatedDetails International Workshop on Gravity, Electrical & Magnetic Methods and Their Applications, Xi'an, China, 19–22 May 2019ISSN (online):2159-6832Copyright: 2019 Pages: 471 publication data© 2019 Published in electronic format with permission by the Society of Exploration Geophysicists and the Chinese Geophysical SocietyPublisher:Society of Exploration Geophysicists HistoryPublished Online: 28 Sep 2019 CITATION INFORMATION Xiaolin Ji, Wanyin Wang, Xiangdong Du, and Xuliang Feng, (2019), "Calculation of the subsalt gravity anomaly based on the minimum curvature technique for potential field data separation," SEG Global Meeting Abstracts : 89-92. https://doi.org/10.1190/GEM2019-023.1 Plain-Language Summary KeywordsseparationgravitysaltPDF DownloadLoading ...

The salt-bearing basins in south-central section of West Africa are located on the east coast of the Atlantic Ocean. The thick salt rock formed during the Aptian period that happened at the transition stage of structural evolution, which is divided into three tectonic sequences: upper salt layer, salt layer and lower salt layer. It is a big challenge to research the major faults that control the boundaries of rifts and morphological dimensions of rifts based on the poor-quality seismic reflection data that is influenced by the shading effect of salt rock. In this paper, we study the subsalt structure of salt-bearing basins in this region using gravity and magnetic anomaly data which have several advantages such as wide area coverage, strong horizontal resolution and less effect from salt rock. In addition, combining the seismic reflection and geologic data, we further study the tectoniv pattern of subsalt in this area. Results suggest that the salt-bearing basins in south-central section of West Africa are characterized by "zones in east west and blocks in south-north". The boundaries of Rio Muni Basin, Gabon Basin, Lower Congo Basin and Kwanza Basin are redefined. Two subsalt rifts and 28 subsalt sags are identiflied, where are present alternating uplifts and depressions. We also infer 16 first-order and 23 second order subsalt faults, which exhibit "extension in east-west and strike-slip in north-east". The results of this study provide geophysical supports to the seismic sequence reanalysis, choosing exploration areas of subsalt oil and gas and the exploration deployment in the next step.

PreviousNext No AccessSEG 2019 Workshop: Fractured Reservoir & Unconventional Resources Forum: Prospects and Challenges in the Era of Big Data, Lanzhou, China, 1–3 September 2019Fracture prediction of buried hill based on wide azimuth seismic data in Bohai BayAuthors: ZhenYu ZhuXiaoLiu WangDongchuan XueJinmiao ZhangXiangdong DuZhenYu ZhuCNOOC Research Institute Co., Ltd.Search for more papers by this author, XiaoLiu WangCNOOC Research Institute Co., Ltd.Search for more papers by this author, Dongchuan XueCNOOC Research Institute Co., Ltd.Search for more papers by this author, Jinmiao ZhangCNOOC Research Institute Co., Ltd.Search for more papers by this author, and Xiangdong DuCNOOC Research Institute Co., Ltd.Search for more papers by this authorhttps://doi.org/10.1190/frur2019_02.1 SectionsAboutPDF/ePub ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareFacebookTwitterLinked InRedditEmail Abstract In order to characterize the strike of fractured reservoirs in Bohai buried hill, the author presents azimuthal anisotropy of NMO velocity extracted by azimuthal gathers based on wide azimuth ocean bottom cable seismic data. The anisotropic ellipse is used to fit NMO velocities from different directions, and the long axis of the ellipse indicates the direction of the fracture. Anisotropic pre-stack time migration can be used to obtain more accurate velocity. Keywords: wide azimuth (WAZ), prestack, time migration, fractures, anisotropyPermalink: https://doi.org/10.1190/frur2019_02.1FiguresReferencesRelatedDetails SEG 2019 Workshop: Fractured Reservoir & Unconventional Resources Forum: Prospects and Challenges in the Era of Big Data, Lanzhou, China, 1–3 September 2019ISSN (online):2159-6832Copyright: 2019 Pages: 120 publication data© 2019 Published in electronic format with permission by the Society of Exploration Geophysicists and the Research Institute of Petroleum & Development-Northwest (NWGI), PetroChinaPublisher:Society of Exploration Geophysicists HistoryPublished Online: 24 Dec 2019 CITATION INFORMATION ZhenYu Zhu, XiaoLiu Wang, Dongchuan Xue, Jinmiao Zhang, and Xiangdong Du, (2019), "Fracture prediction of buried hill based on wide azimuth seismic data in Bohai Bay," SEG Global Meeting Abstracts : 5-8. https://doi.org/10.1190/frur2019_02.1 Plain-Language Summary Keywordswide azimuth (WAZ)prestacktime migrationfracturesanisotropyPDF DownloadLoading ...

The exploration and development of oil and gas in China's offshore regions is marked by new challenges because targets are changing from shallow to deeper reservoirs and from structural to complex lithologic reservoirs.Increasing difficulty in exploration demands advanced seismic exploration technologies.Based on a comprehensive analysis of the challenges of deepwater oil and gas exploration,several new technological advancements are reviewed in this study.For seismic acquisition,high precision streamer acquisition equipment and the "plow" broadband seismic acquisition technology stand out.For seismic processing and interpretation,τ-p domain deghosting and reverse time migration technologies for broadband seismic data are investigated.For development seismology,marine time-lapse seismic technology,etc.,are considered.In particular,breakthrough progress occurred in the fields of marine broadband seismic exploration technology and marine time-lapse seismic technology.Both play an important role in the exploration and production of oil and gas in the deepwater fields of the South China Sea,which is the main energy supplying region of China,and provide technical support for the growing exploration and production of offshore oil and gas reserves.

The frequency dependent reflection coefficient can be obtained by time frequency analysis,based on the AVO theory.Using FAVO (Frequency dependent AVO) inversion technique,the authors obtained the property of velocity dispersion degree.Because of the correlation between the velocity dispersion and pore fluid,the property can be used in fluid detection in the reservoir as an identification factor.In this paper,the authors derived the inversion formula and chose the deep-water sandstone reservoir as the research target.The research on gas sand-body characterization and gas content identification was based on 1D numerical model and 2D real section.The inversion results are well coincident with the drilling results,which shows the effectiveness of the technique in fluid identification of deepwater sandstone reservoirs.

The attenuation and dispersion obviously occur during the seismic wave propagation in the porous media.The major cause of this effect contains two kinds of mechanisms:one is the viscoelastic mechanism of solid skeleton,and the other is the flow mechanism of porous fluid.Both mechanisms have its limitations when being studied independently.The seismic wave attenuation caused by fluid flow in porous has been ignored when the reservoir is equivalent as a solid in Zener linear solid model,which describes viscoelastic mechanism.BISQ model considers the two phases in reservoir and the fluid flow mechanism in both macroscopic porous and microscopic porous.However,the attenuation band described by BISQ model is too high,and it cannot give an explanation of the obviously attenuation phenomenon in seismic band.In this paper,we analysis the mechanisms of both Zener model and BISQ model,and after that we derive the constitutive equation of the Zener-BISQ model by combining these two models.The attenuation and dispersion characteristics of phase velocity and inverse quality factor are analyzed by solving the plane wave solutions of new model.Finally,the effect and control mode of the Zener model have been studied by three numerical experiments.

Russell流体因子是表征储层孔隙流体特征的重要敏感流体因子,其提取结果的可靠性是决定流体判识质量的核心问题之一.叠前地震反演是提取流体因子的主要途径,而反射系数近似方程是叠前反演的基础.结合Biot-Gassmann多孔弹性介质理论对反射系数近似方程进行了重新推导,得到了包含Russell流体因子的孔隙弹性介质反射系数线性近似方程;通过分析方程的精度和反演敏感特征,验证了新反射系数近似方程的可靠性和Russell流体因子项的高反演敏感度;最终基于贝叶斯反演框架的AVO反演实现了Russell流体因子的定量提取.模型试算和实际应用结果表明,基于新反射系数近似方程的叠前反演方法能够稳定可靠地从地震资料中提取Russell流体因子,为储层流体识别提供了一种新的流体因子计算方法.

The Bone Basin is located in the eastern Indonesia.The potential of oil and gas cannot be ignored.The reserves of oil and gas are connected with the evolution of the Bone Basin,and the geological factors,such as the tectonic system,magmatic activity.In order to provide geophysical basis for further area of oil and gas,the fault of structure and tectonic zoning of the Bone basin in Indonesia are studied by using satellite gravity data.In this study,nine faults are deduced with edge recognition technology based on the normalized vertical derivative of the total horizontal derivative (NVDR_THDR) for potential data,which contains four basincontrolling faults and five depression-controlling faults.By using the minimum curvature technique for potential field data separation,the boundary of the Bone basin and three secondary-tectonic units and ten third-structural units are divided,combined with the distribution of the faults.According to Fast solution of forward and inversion problems for gravity field in a dual interface model,the thickness distribution of sedimentary layer in Bone basin is obtained.In this paper,the Bone basin is the trend of NNW,and presents the pattern of ‘ Belt east-west,north-south block’.the distribution of the NNW-fault control the the distribution of the Bone Basin,which presents ‘ Belt east-west’,the distribution of the NEfault control the the boundary of the tectonic units,which presents ‘north-south block’.Through research,the relationship between the Bone Basin and Eastern Sengkang Basin is further cleared,we think the Eastern Sengkang Basin is one of depressions in the Bone Basin.

The complex structural condition in the Southern Apennine region of Italy results in poor seismic imaging quality, great difficulty in defining traps,and unclear character of petroleum entrapment. We believe that the structural evolution controls the distribution of high quality source rocks. The stable structural environment plays a constructive role in the development of source rocks. The intense structural evolution plays an inhibition role in the distribution and development of source rocks. The structural belt controls the type of reservoirs,traps and the distribution pattern. The primary reservoir in the thrust fold belt is Cretaceous carbonatite;the primary reservoir in the internal foredeep belt is turbidite sandstones of Pliocene–Pleistocene;the primary reservoir in the external foredeep belt is Pliocene turbidite sandstones and Miocene carbonatite,and the primary reservoir in the forebulge belt is Miocene–Cretaceous carbonatite. The structural paleogeography controls the distribution of petroleum systems. During the syn-rift stage in Mesozoic,the distribution pattern of paleo-uplift and depression controlled the oil and associated gas. During the collision stage in Cenozoic,the rapid subsidence of foredeep belt controlled the thermorgenic gas system. The biogas system migrated outward gradually along with the migration of depocenter in foreland basin during Quaternary.

Albert湖盆非固结砂岩储层发育,受物性参数变化大以及孔隙流体类型差异的影响,振幅属性和声阻抗参数无法预测储层的整体展布.岩石物理分析结果揭示泊松阻抗参数具有敏感的区域岩性判识能力,但研究区仅有小角度和中角度部分叠加资料,限制了泊松阻抗参数的有效计算.针对Albert湖盆的地质与地球物理问题,以N油田为例,提出了一套适用于非固结砂岩储层预测的两角度弹性阻抗反演方法,并在岩石物理统计分析的指导下,进一步利用纵、横波阻抗数据实现了泊松阻抗的计算,为非固结砂岩储层预测提供了数据支撑.模型试算结果验证了该方法的可行性,且实际应用效果表明,预测的砂体与实钻结果吻合较好.

麻坑是由于地下流体超压喷发而在海底形成的凹陷坑.按其分布层位可划分为层间麻坑和海底麻坑,而海底麻坑又可按其活跃状态划分为海底休眠型麻坑和海底活跃型麻坑.海底麻坑是全球海域含油气沉积盆地普遍发育的一种麻坑类型,而层间麻坑是一种较少见的麻坑类型.在研究西南非海岸盆地油气成藏条件时,发现该盆地发育层间麻坑现象.这种层间麻坑具有多期次发育的特点,在地震剖面上表现为强振幅、多期同相轴下拉叠加的特点,剖面形态为“V”或“U”型,从三维地震数据体沿层属性切片上能看到明显的异常带.本文通过对三维地震数据的解释,较为系统地研究了西南非海岸盆地层间麻坑的构型、演化模式及形成机理,并简要总结了层间麻坑对盆地油气勘探的指示意义.

海底麻坑是由于地下流体在高压下喷发而在海底形成的凹陷坑,可作为地下油气的直接指示.加蓬海岸盆地发现大量的海底麻坑,其地震反射同相轴表现为下拉特征,且地震反射振幅和相干属性均出现异常.该盆地海底麻坑的平面分布规律与下伏盐岩活动及盐岩展布有很大的相关性.通过对三维地震资料的解释,初步研究了加蓬海岸盆地海底麻坑的成因和形成模式.通过分析发现,该地区海底麻坑形成与下伏盐岩活动有关,盐底辟运动造成附近油气泄露产生相关气烟囱、亮点和海底麻坑等现象.海底麻坑可以成为下伏油气系统的直接指示,该地区的麻坑可以有效指示油气系统的展布范围和盐岩分布规律,预测断裂发育和有效圈闭带.对海底麻坑的深入研究有利于我们更好地优选勘探区带和区决,更好地了解研究区地下油气的分布规律.

东非裂谷Albertine地堑是当今世界油气勘探的热点地区之一,具有埋藏浅、演化快、地层新的地质特点.作为主力含油气层段的新生代地层中疏松砂岩异常发育,物性参数差异较大,受控于孔隙度以及孔隙流体的综合影响,含油气储层的地震响应无明显规律,油气预测难度较大.基于能量吸收分析思想的指导,在利用匹配追踪时频分解方法有效提高时频分辨率的前提下,进一步提出瞬时能量异常属性的计算方法.以Albertine地堑的W油田为例,针对含油气储层表现的低频能量增加、高频能量衰减的异常特征,借助瞬时能量异常属性实现了油气预测,预测结果获得了钻井的验证.

North Carnarvon盆地位于澳大利亚西北大陆架的南部,是一个自晚古生代至新生代持续沉降形成的巨型含油气盆地,其中Exmouth高地是该盆地主要的地质单元,自2008年以来发现三叠系Mungaroo组气田30个.在对Exmouth高地进行地震资料解释时发现,该区域具有许多特殊的地质现象,如具有大量各异的区域不整合面;断裂系统靠近外缘展布且具有一定规律;三叠系三角洲地层沉积现象特殊等.结合区域地质资料,利用板块运动理论,进一步对上述现象进行了分析和总结.通过对各个时期区域板块间相对位置和相对运动的分析发现,板块运动控制着这个区域的构造沉积演化,进一步控制着区域的油气成藏.通过对板块运动的研究,总结了区域油气勘探的一般性规律.

阿拉伯板块构造—沉积演化为卡塔尔古生界油气聚集成藏提供了有利的石油地质条件.分析认为,卡塔尔在志留系底部发育一套优质的烃源岩(笔石热页岩),发育两套有利的碎屑岩储盖组合,储层以河流—三角洲相砂岩为主,埋深普遍大于3600m,总体较为致密,以中—低孔、低渗为主,但在局部仍可能发育储层物性较好的“甜点”,具备较好的产能特性.古生界圈闭类型主要有背斜、断背斜、地层上倾尖灭岩性圈闭和与不整合相关的地层圈闭,具有3种油气成藏模式,以下生上储垂向断裂输导运聚成藏模式为主.海西构造挤压和盐流活动隆升作用对古生界的圈闭形成起了决定性作用,圈闭的主要形成时期为晚二叠世—晚三叠世,早于志留系烃源岩大量生排烃期,成藏条件匹配关系优越.卡塔尔碎屑岩层系勘探具有优越的烃源岩物质基础、有利的储盖组合、有利的构造圈闭聚集区和优越的油气成藏条件,且勘探程度极低,具有较大的油气勘探潜力,主要的有利勘探潜力区为卡塔尔隆起的侧翼和东部的南海湾盐盆区.