塔里木、四川和鄂尔多斯盆地海相碳酸盐岩规模储层发育地质背景初探   总被引：5，自引：2，他引：3  

赵文智  沈安江  胡安平  周进高  倪新锋 《岩石学报》2015,31(11):3495-3508

前人对碳酸盐岩储层的研究重点关注储层的特征和成因上,很少关注规模储层发育的地质背景问题,而这又是深层油气勘探不可回避的问题。本文基于塔里木、四川和鄂尔多斯盆地碳酸盐岩储层实例分析,提出了不同类型储层规模发育的地质背景,认为相控型碳酸盐岩规模储层主要发育于蒸发台地、碳酸盐缓坡及台地边缘三类沉积背景,成岩型碳酸盐岩规模储层发育的控制因素复杂,具有较大的不确定性,受先存储层规模及热液规模的控制,受区域构造运动控制的成岩型储层一般具备规模发育的条件。本文还特别讨论了镶边台缘背景下台内礁滩储层的规模问题,指出障壁类型、障壁的连续性、台地类型、台内水深和地貌共同控制台内礁滩储层的规模。规模储层发育地质背认识对深层碳酸盐岩勘探领域评价具重要的指导意义,指出了塔里木、四川和鄂尔多斯盆地近期值得关注的礁滩、岩溶和白云岩三类深层碳酸盐岩储层勘探领域。  相似文献   

Three‐dimensional modelling and sequence stratigraphy of a carbonate ramp‐to‐shelf transition,Permian Upper San Andres Formation     

RYAN M. PHELPS  CHARLES KERANS  SAM Z. SCOTT  XAVIER JANSON  JEROME A. BELLIAN 《Sedimentology》2008,55(6):1777-1813

This study highlights three‐dimensional variability of stratigraphic geometries in the ramp crest to basin of mixed carbonate–siliciclastic clinoforms in the Permian San Andres Formation. Standard field techniques and mapping using ground‐based lidar reveal a high degree of architectural complexity in channellized, scoured and mounded outer ramp stratigraphy. Development of these features was a function of location along the ramp profile and fluctuations in relative sea‐level. Deposition of coarse‐grained and fine‐grained turbidites in the distal outer ramp occurred through dilute and high‐density turbidity flows and was the result of highstand carbonate shedding within individual cycles. In this setting, high‐frequency cycles of relative sea‐level are interpreted on the basis of turbidite frequency, lateral extent and composition. Submarine siliciclastic sediment bypass during lowstand cycles resulted in variable degrees of siliciclastic preservation. Abundant siliciclastic material is preserved in the basin and distal outer ramp as point‐sourced lowstand wedges and line‐sourced early transgressive blankets. In mounded topography of the outer ramp, siliciclastic preservation is minimal to absent, and rare incised channels offer the best opportunity for recognition of a sequence boundary. Growth of mounded topography in the outer ramp began with scouring, followed by a combination of bioherm construction, fusulinid mound construction and isopachous draping. Intermound areas were then filled with sediment and continued mound growth was prevented by an accommodation limit. Mound growth was independent of high‐frequency cycles in relative sea‐level but was dependent on available accommodation dictated by low‐frequency cyclicity. Low‐angle ramp clinoforms with mounded topography in the outer ramp developed during the transgressive part of a composite sequence. Mound growth terminated as the ramp transformed into a shelf with oblique clinoform geometries during the highstand of the composite sequence. This example represents a ramp‐to‐shelf transition that is the result of forcing by relative sea‐level fluctuations rather than ecologic or tectonic controls.  相似文献   

Palaeoenvironments, palaeogeography, and physiography of a large, shallow, muddy ramp: Late Cenomanian-Turonian Kaskapau Formation, Western Canada foreland basin     

BOGDAN L. VARBAN  A. GUY PLINT 《Sedimentology》2008,55(1):201-233

The Kaskapau Formation spans Late Cenomanian to Middle Turonian time and was deposited on a low‐gradient, shallow, storm‐dominated muddy ramp. Dense well log control, coupled with exposure on both proximal and distal margins of the basin allows mapping of sedimentary facies over about 35 000 km². The studied portion of the Kaskapau Formation is a mudstone‐dominated wedge that thins from 700 m in the proximal foredeep to 50 m near the forebulge about 300 km distant. Regional flooding surfaces permit mapping of 28 allomembers, each of which represent an average of ca 125 kyr. More than 200 km from shore, calcareous silty claystone predominates, whereas 100 to 200 km offshore, mudstone and siltstone predominate. From about 30 to 100 km offshore, centimetre‐bedded very fine sandstone and mudstone record along‐shelf (SSE)‐directed storm‐generated geostrophic flows. Five to thirty kilometres from shore, decimetre‐bedded hummocky cross‐stratified fine sandstone and mudstone record strongly oscillatory, wave‐dominated flows whereas some gutter casts indicate shore‐oblique, apparently mostly unidirectional geostrophic flows. Nearshore facies are dominated by swaley cross‐stratified or intensely bioturbated clean fine sandstone, interpreted as recording, respectively, areas strongly and weakly affected by discharge from distributary mouths. Shoreface sandstones grade locally into river‐mouth conglomerates and sandstones, including conglomerate channel‐fills up to 15 m thick. Locally, brackish lagoonal shelly mudstones are present on the extreme western margin of the basin. There is no evidence for clinoform stratification, which indicates that the Kaskapau sea floor had extremely low relief, lacked a shelf‐slope break, and was probably nowhere more than a few tens of metres deep. The absence of clinoforms probably indicates a long‐term balance between rates of accommodation and sediment supply. Mud is interpreted to have been transported >250 km offshore in a sea‐bed nepheloid layer, repeatedly re‐suspended by storms. Fine‐grained sediment accumulated up to a ‘mud accommodation envelope’, perhaps only 20 to 40 m deep. Continuous re‐working of the sea floor by storms ensured that excess sediment was redistributed away from areas that had filled to the ‘accommodation envelope’, being deposited in areas of higher accommodation further down the transport path. The facies distributions and stratal geometry of the Kaskapau shelf strongly suggest that sedimentary facies, especially grain‐size, were related to distance from shore, not to water depth. As a result, the ‘100 to >300 m’ depth interpreted from calcareous claystone facies for the more central parts of the Interior Seaway, might be a significant overestimate.  相似文献   

江西宜丰-德兴叠覆造山带的基本特征及其意义     

吴富江  余江  刘春根  邓金火 《地质通报》2016,35(1):181-187

宜丰—德兴一带存在新的一种造山带类型,称之为晋宁期—加里东期宜丰-德兴叠覆型造山带,总体呈半月形舌状展布,是经北南双向多期碰撞叠覆的隐伏-半隐伏型造山带。经对多个出露于造山带内的构造岩片进行时态、位态、相态的研究与恢复,建立了该造山带的结构样式和构造演化序列,具有3层结构模式。分别由代表中新元古代华南洋的残迹蛇绿混杂岩、扬子陆缘弧前盆地火山-沉积变质岩系、下南华统次深海相沉积的浅变质岩片与怀玉—广丰地区青白口纪晚期—早古生代沉积的下南华统浅变质岩片组成。造山带两侧的宜丰-景德镇与德兴-弋阳推覆带是中国重要的铜、金多金属矿集区,伏于变质岩之下的晚古生代煤系地层有巨大的找煤潜力。  相似文献   

渤海湾地区构造变换带及油气意义   总被引：2，自引：0，他引：2       下载免费PDF全文

余一欣  周心怀  魏刚  汤良杰  徐长贵 《古地理学报》2008,10(5):555-560

利用地震剖面解释结果和构造编图成果,分析了渤海湾地区构造变换带的特征及其油气地质意义。渤海湾地区主要发育区域横向调节带和局部变换带两类构造变换带。区域横向调节带由北西向大型走滑断裂带充当,这些断裂带同时也是强地震活动带,将渤海海域地区分为北、中、南3段。局部变换带主要发育在相互作用的分段正断层的叠置区内。根据分段正断层的倾向及其组合特征,可将局部变换带分为转换斜坡型、斜向背斜型和地垒型3类。渤海湾地区构造变换带具有重要的油气地质意义,主要表现为控制构造圈闭的形成、有利于优质储集层的发育及控制油气运移过程等。  相似文献   

TEM法斜坡函数断电效应的修正及正反演计算     

胡建德 《煤田地质与勘探》1995,23(1):51-54

介绍了层状大地上水平共平面共心线框在阶跃函数或矩形脉冲激发时使用Gaver-Stehfest算法计算互阻抗的方法以及斜坡函数断电效应的修正、给出了重叠回线装置时全时域视电阻率的计算方法和TEM资料的反演算法。   相似文献   

Aeolian sediment transport on a recovering storm‐eroded foredune with sand fences          下载免费PDF全文

Nancy L. Jackson  Karl F. Nordstrom 《地球表面变化过程与地形》2018,43(6):1310-1320

Studies of sediment transport on developed coasts provide perspective on how human adjustments alter natural processes. Deployment of sand‐trapping fences is a common adjustment that changes the characteristics of the dune ramp and its role in linking sediment transfers from the backshore to the foredune. Fence effects were evaluated in the field using anemometer arrays and vertical sediment traps placed across a beach and dune at Seaside Park, New Jersey, USA during onshore and longshore winds. The foredune is 18 m wide and 4.5 m above the backshore. The mean speed of onshore winds at 0.5 m elevation decreased by 17% from the berm crest to the upper ramp and 36% in the lee of a fence there. Sediment transport during mean wind speeds up to 8.0 m s^?1 at 0.5 m elevation was < 0.06 kg m^?1 h^?1 on the berm crest and backshore where fetch distances were < 45 m and surface sediment was relatively coarse (0.74–0.85 mm) but increased to 5.63 kg m^?1 h^?1 on the upper ramp aided by the longer fetch distances (up to 82 m) and finer grain size of the source sediment there (0.52 mm). Sediment transport along the berm crest and backshore during longshore winds, where fetch distances were > 200 m, was up to 58.69 kg m^?1 h^?1, about three orders of magnitude greater than during the onshore winds. Fences can displace the toe of the ramp farther seaward than would occur under natural conditions. They can create a gentler slope and change the shape of the ramp to a more convex form. A fence on the ramp can cut off a portion of sediment supply to the upper slope. Decisions about fence placement thus should consider these morphologic changes in addition to the effects on dune volume. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献   

斜阶跃波层状介质航空瞬变电磁响应数值计算   总被引：1，自引：0，他引：1  

关珊珊  林君  嵇艳鞠  许洋铖  万玲  王远 《吉林大学学报(地球科学版)》2012,(Z1):435-440

目前,航空瞬变电磁方法数据解释主要采用阶跃波均匀半空间模型计算视电导率值,而实际航空电磁系统发射波形的下降沿多为斜阶跃,导致解释时计算的视电导率值存在较大偏差。为此,笔者研究了航空瞬变电磁系统发射电流为斜阶跃时的电磁响应数值计算,将发射波形进行拉氏变换,利用G-S逆拉氏变换与241点汉克尔变换相结合的方法,实现斜阶跃波关断后的层状大地模型航空瞬变电磁响应计算;并对均匀半空间和层状大地模型下,不同关断时间和不同飞行高度对电磁响应的影响进行分析。得出结论:不同关断时间,关断后取样延时2 ms时,均匀半空间电磁响应的平均偏差为27.78%,三层模型的平均偏差为32.16%;当飞行高度从20 m增加到60 m时,均匀半空间和三层模型的感应电动势分别减小了43.6%和83.2%。  相似文献   

Ichnology and sedimentology of the Triassic carbonates of North‐west Sardinia,Italy     

DIRK KNAUST  LUCA G. COSTAMAGNA 《Sedimentology》2012,59(4):1190-1207

The classical Middle to Upper Triassic carbonate sections at Monte Santa Giusta and Punta del Lavatoio, North‐west Sardinia (Italy), referred to the Muschelkalk and Keuper lithofacies group, are revisited and their trace fossil content is investigated for the first time. A combined ichnological and sedimentological study reveals insights into the depositional environments, regional context, palaeogeography and sequence stratigraphy. The results indicate deposition on a homoclinal carbonate ramp with broad facies belts. All recognized trace fossils are also known from time‐equivalent deposits of Germany and thus indicate a close affinity between the North‐west Sardinian Triassic and the Germanic Basin. Only a few trace fossils are particularly abundant and these indicate opportunistic colonization by their producers, which is probably related to restricted endobenthic conditions due to reduced oxygen and/or increased salinity. The trace fossil association can be grouped into a softground suite belonging to the Cruziana ichnofacies, and a firmground suite of the Glossifungites ichnofacies. This discrimination enables an interpretation of the northern Monte Santa Giusta section as a carbonate ramp with extensive tidal flats and abundant carbonate accumulation in a relatively proximal position, whereas the southern Punta del Lavatoio section exhibits broad lagoonal environments with reduced sedimentation in a deeper and more Tethys‐influenced area. The Sardinian sections are ichnologically similar to the Anisian–Ladinian succession known from the Tatra Mountains, but differ from it by having a slightly higher ichnodiversity, which again can be attributed to a less restricted lagoonal environment. This study demonstrates the importance of integrating trace fossil analysis in sedimentological and palaeontological investigations of carbonate systems.  相似文献   

Sharp‐based marine sandstone bodies in the Mulichinco Formation (Lower Cretaceous), Neuquén Basin,Argentina: remnants of transgressive offshore sand ridges     

ERNESTO SCHWARZ 《Sedimentology》2012,59(5):1478-1508

The interpretation of sharp‐based shallow‐marine sandstone bodies encased in offshore mudstones, particularly transgressive units, has been a subject of recent debate. This contribution provides a multiple‐dataset approach and new identification criteria which could help in the recognition of transgressive offshore sandstone bodies worldwide. This study integrates sedimentology, ichnology, taphonomy and palaeoecology of Mulichinco Formation strata in the central Neuquén Basin (Argentina) in order to describe and interpret sharp‐based sandstone bodies developed in ramp‐type marine settings. These bodies are sandwiched between finer‐grained siliciclastics beneath and thin carbonates above. The underlying sediments comprise progradational successions from offshore mudstones to offshore transition muddy sandstones, grading occasionally into lower shoreface sandstones. The surfaces capping the regressive siliciclastics are flat and regionally extensive, and are demarcated by skeletal concentrations and a Glossifungites suite; they are also marked by sandstone rip‐up clasts, with encrustations and borings on all sides. These surfaces are interpreted as composite discontinuities, cut during a relative sea‐level fall and remodelled during the initial transgression. The overlying transgressive sandstone bodies are 3 to 7 m thick, >4 km long and about three times longer than wide; they are composed of fine‐grained sandstones with little lateral change in grain size. Cross‐stratification and/or cross‐lamination are common, typically with smaller‐scale structures and finer grain size towards the top. Large‐scale, low‐angle (5° to 8°) inclined stratification is also common, dipping at ca 30° with respect to body elongation and dominant currents. These sandstone bodies are interpreted as offshore sand ridges, probably developed under the influence of tidal currents. Intense burrowing is typical at the top of each unit, suggesting an abandonment stage. Final deactivation favoured colonization by epibenthic‐dominated communities and the formation of skeletal‐rich limestones during the latest transgressive conditions. As partial reworking of pre‐existing ridges occurred during this stage, the Mulichinco sandstone bodies are considered the remnants of transgressive offshore sand units.  相似文献