Characteristics and petroleum origin of the Carboniferous volcanic rock reservoirs in the Shixi Bulge of Junggar Basin,western China     

《Marine and Petroleum Geology》2017

Shixi Bulge of the central Junggar Basin in western China is a unique region that provides insight into the geological and geochemical characteristics of large-scale petroleum reservoirs in volcanic rocks of the western Central Asian Orogenic Belt. Carboniferous volcanic rocks in the Shixi Bulge mainly consist of striped lava and agglomerate, as well as breccia lava and tight tuff. Volcanic rocks differ in porosity and permeability. Striped lava exhibits the highest porosity (average: 14.2%) but the lowest permeability (average: 0.67 × 10⁻¹⁵ m) among the rock types. Primary gas pores are widely developed and mostly filled. Secondary dissolution pores and fractures are two major reservoir storage spaces. Capillary pressure curves suggest the existence of four pore structure types of reservoir rocks. Several factors, namely, lithology, pore structure, and various diagenesis, govern the physical properties of volcanic rocks. The oil is characterized by a high concentration of tricyclic terpane, a terpane distribution of C₂₃ < C₂₁ > C₂₀, and sterane distributions of C₂₇ < C₂₈ < C₂₉ and C₂₇ > C₂₈ < C₂₉. Oil and gas geochemistry revealed that the oil is a mixture derived primarily from P₂w source rock and secondarily from P₁j source rock in the sag west of Pen-1 Well. The gases are likely gas mixtures of humic and sapropelic organic origins, with the sapropelic gas type dominant in the mixture. The gas mixture is most likely cracked from kerogen rather than oils. The Carboniferous volcanic reservoirs in Shixi Bulge share some unique characteristics that may provide useful insights into the various roles of different volcanic reservoir types in old volcanic provinces. The presence of these reservoirs will undoubtedly encourage future petroleum exploration in volcanic rocks up to the deep parts of sedimentary basins.  相似文献   

Fluid sources and stable isotope signatures in authigenic carbonates from the Northern Apennines,Italy     

《Marine and Petroleum Geology》2017

Authigenic carbonates are frequently associated with methane cold-seep systems, which extensively occur in various geologic settings worldwide. Of interest is the relation between the fluids involved in their formation and the isotopic signals recorded in the carbonate cements. Along the Northern Apennines foothills (Italy), hydrocarbons and connate waters still seeping nowadays are believed to be the primary sources for the formation of fossil authigenic carbonate found in Plio-Pleistocene marine sediments. Four selected outcrops of dolomitic authigenic carbonates were analysed to compare signature of seeping fluids with fractionation of stable carbon and oxygen isotopes recorded in the carbonate.Along the foothills, deep methane-rich fluids spontaneously rise to the surface through mud volcanoes or are exploited in wells drilled nearby to the fossil Plio-Pleistocene authigenic carbonates. The plumbing system providing fluids to present-day cold seeps was structurally achieved in Late Miocene and Plio-Pleistocene. δ¹³C values of methane, which vary from −51.9 to −43.0‰ VPDB, indicate that gas composition from the deep hydrocarbon reservoirs is relatively uniform along the foothills. On the contrary, δ¹³C in fossil authigenic carbonates strongly varies among different areas and also within the same outcrop.The different carbon sources that fed the investigated carbonates were identified and include: thermogenic methane from the deep Miocene reservoirs, ¹³C-enriched CO₂ derived from secondary methanogenesis and microbial methane from Pliocene successions buried in the Po Plain. The δ¹³C variability documented among samples from a single outcrop testifies that the authigenic carbonates might represent a record of varying biogeochemical processes in the hydrocarbon reservoirs. The sources of stable oxygen isotopes in authigenic carbonates are often ascribed to marine water. Oxygen isotopic fractionation in the dolomite cements indicates that marine pore water couldn't be the sole source of oxygen. δ¹⁸O values provide a preliminary evidence that connate waters had a role in the carbonates precipitation. The concomitant occurrence of active cold seepages and fossil record of former plumbing systems suggests that generation and migration of hydrocarbons are long-lasting and very effective processes along the Northern Apennines foothills.  相似文献   

Impact of strong easterly trade winds on carbonate petroleum exploration - Relationships developed from Caicos Platform,southeastern Bahamas     

《Marine and Petroleum Geology》2017

Brisk, persistent easterly trade wind influences define Holocene patterns of carbonate sedimentation across the Caicos Platform (southeastern Bahamas). Resultant predictive sedimentary facies models based on trade wind influences are more widely applicable to the exploration for subsurface carbonate plays than are existing models based on the northern Bahamas facies patterns, which are characterized by gentle trade winds and strong platform-margin-related oceanic processes (swells and tidal currents). The Caicos Platform relationships may be more applicable because many ancient shallow carbonate depositional environments were within the trade wind belts and commonly within broad intracratonic seas that were little influenced by oceanic processes.The grainstone-dominated Caicos Platform exhibits reservoir potential over much of its surface, in contrast to northern Bahamian platforms, where oceanic tidal currents or swells and gentle easterly trade winds confine higher energy environments with reservoir potential to platform margins. Strong easterly trade winds across Caicos Platform promote widespread Holocene platform-interior oolitic, skeletal and grapestone grainstone bodies on this platform. Orientations of ooid sand bodies vary depending on preexisting topography, water depth and bottom energy. Shallow subtidal ooid sand shoals orient parallel to these winds. Ooid sands developed along older shorelines orient parallel to the shorelines but prograde perpendicular into these winds. Deeper platform-interior oolitic sands exist as widespread, sheet-like deposits. These trade winds allow reefs and ooids to coexist in many settings, permit isolated linear reefs to flourish on certain leeward platform margins, and promote effective off-bank transport of carbonate sands that create onlapping grainstone wedges. These relationships are very applicable to the rock record.Strong trade wind influences, such as seen on Caicos Platform, better explain the occurrence of Cretaceous reef and/or oolitic grainstone reservoirs developed well in from platform margins (Fairway Field in East Texas; Black Lake Field in Louisiana) than do existing northern Bahamian models. Depositional models based on conditions in the northern Bahamian models would predict low-energy facies in these platform-interior settings. A trade-wind-driven depositional model, characterized by strong persistent easterlies, also better explains the origin of the onlapping wedge of skeletal grainstones at Poza Rica oilfield in Mexico.The Caicos Platform easterly trade-wind-driven depositional model should generally apply to any ancient shallow carbonate environment that developed 5–22° north or south of the paleoequator, whether or not a platform margin was near by. Future carbonate exploration or exploitation should always factor in not only geological age, but also physiographic, latitudinal and climatic setting at a global and local scale.  相似文献   

Petroleum retention in the Mandal Formation,Central Graben,Norway     

《Marine and Petroleum Geology》2017

Upper Jurassic organic matter-rich, marine shales of the Mandal Formation have charged major petroleum accumulations in the North Sea Central Graben including the giant Ekofisk field which straddles the graben axis. Recent exploration of marginal basin positions such as the Mandal High area or the Søgne Basin has been less successful, raising the question as to whether charging is an issue, possibly related to high thermal stability of the source organic matter or delayed expulsion from source to carrier.The Mandal Formation is in part a very prolific source rock containing mainly Type II organic matter with <12 wt.-% TOC and HI < 645 mg HC/g TOC but Type III-influenced organofacies are also present. The formation is therefore to varying degrees heterogeneous. Here we show, using geochemical mass balance modelling, that the petroleum expulsion efficiency of the Mandal Formation is relatively low as compared to the Upper Jurassic Draupne Formation, the major source rock in the Viking Graben system. Using maturity series of different initial source quality from structurally distinct regions and encompassing depositional environments from proximal to distal facies, we have examined the relationship between free hydrocarbon retention and organic matter structure. The aromaticity of the original and matured petroleum precursors in the Mandal source rock plays a major role in its gas retention capacity as cross-linked monoaromatic rings act on the outer surface of kerogen as sorptive sites. However, oil retention is a function of both kerogen and involatile bitumen compositions. Slight variations in total petroleum retention capacities within the same kerogen yields suggest that texture of organic matter (e.g. organic porosity) could play a role as well.  相似文献   

Petroleum prospectivity of the Canada Basin, Arctic Ocean     

Arthur Grantz  Patrick E. Hart 《Marine and Petroleum Geology》2012,30(1):126-143

Reconnaissance seismic reflection data indicate that Canada Basin is a >700,000 sq. km. remnant of the Amerasia Basin of the Arctic Ocean that lies south of the Alpha-Mendeleev Large Igneous Province, which was constructed across the northern part of the Amerasia Basin between about 127 and 89-83.5 Ma. Canada Basin was filled by Early Jurassic to Holocene detritus from the Beaufort-Mackenzie Deltaic System, which drains the northern third of interior North America, with sizable contributions from Alaska and Northwest Canada. The basin contains roughly 5 or 6 million cubic km of sediment. Three fourths or more of this volume generates low amplitude seismic reflections, interpreted to represent hemipelagic deposits, which contain lenses to extensive interbeds of moderate amplitude reflections interpreted to represent unconfined turbidite and amalgamated channel deposits.Extrapolation from Arctic Alaska and Northwest Canada suggests that three fourths of the section in Canada Basin is correlative with stratigraphic sequences in these areas that contain intervals of hydrocarbon source rocks. In addition, worldwide heat flow averages suggest that about two thirds of Canada Basin lies in the oil or gas windows. Structural, stratigraphic and combined structural and stratigraphic features of local to regional occurrence offer exploration targets in Canada Basin, and at least one of these contains bright spots. However, deep water (to almost 4000 m), remoteness from harbors and markets, and thick accumulations of seasonal to permanent sea ice (until its possible removal by global warming later this century) will require the discovery of very large deposits for commercial success in most parts of Canada Basin.  相似文献   

Relating petroleum system and play development to basin evolution: West African South Atlantic basins   总被引：2，自引：0，他引：2  

Suzanne E. Beglinger  Harry DoustSierd Cloetingh 《Marine and Petroleum Geology》2012,30(1):1-25

Sedimentary basins can be classified according to their structural genesis and evolutionary history and the latter can be linked to petroleum system and play development. We propose an approach in which we use the established concepts in a new way: breaking basins down into their natural basin cycle division, then defining the characteristics of each basin cycle (including the type of petroleum systems and plays they may contain) and comparing them with similar basin cycles in other basins, thereby providing a means to learn through a greater population of (perhaps not immediately obvious) analogues. Furthermore, we introduce the use of the trajectory plot as a new tool in such an analysis. This methodology has been applied to the West African South Atlantic marginal basins between Cameroon and Angola, and we demonstrate that the similar tectonostratigraphic evolution of the individual basins along this margin has led to the development of similar types of petroleum systems and play (level)s. Consequently, we can make analogue comparisons among these basins in order to evaluate and predict the presence of potential, yet undiscovered, hydrocarbon accumulations in less well explored parts of the margin.  相似文献   

下扬子区海相中、古生界地质结构分区及其油气勘探选区意义   总被引：1，自引：1，他引：0  

李亚辉  段宏亮  谈迎 《地质力学学报》2010,16(3):271-280

基于对下扬子区海相中、古生界构造及沉积沉降特征的研究, 以影响和反映构造稳定及晚期生烃的基底性质、构造变形特征、印支面埋深、沉积沉降中心迁移特征等为依据, 将下扬子区划分为5个一级、17个二级地质结构区。以构造稳定、有效保存及晚期生烃、晚期成藏等为评价标准, 综合评价南黄海中部晚期隆起稳定区(Ⅰ₂)、江都-东台-南黄海南部晚期沉降深冲断区(Ⅰ₃)、泰兴-海安晚期沉降深冲断区(Ⅱ₁)、南通-南黄海南部晚期沉降浅推覆区(Ⅱ₂)及太湖晚期沉降浅推覆区(Ⅱ₄)为下古生界油气勘探有利区; 南黄海北部晚期沉降深冲断区(Ⅰ₁)、江都-东台-南黄海南部晚期沉降深冲断区(Ⅰ₃)、滨海-大丰晚期沉降深下古卷入区(Ⅰ₄)和泰兴-海安晚期沉降深冲断区(Ⅱ₁)为上古生界油气勘探有利区; 南黄海北部晚期沉降深冲断区(Ⅰ₁)、滨海-大丰晚期沉降深下古卷入区(Ⅰ₄)、金湖-高邮晚期沉降深下古卷入区(Ⅰ₅)及泰兴-海安晚期沉降深冲断区(Ⅱ₁)为古潜山油气勘探有利区。研究对于该区海相中古生界勘探选区具有重要意义。   相似文献   

中亚地区阿拉伊盆地构造地质特征与油气条件分析     

郇玉龙 《海相油气地质》2009,14(2)

阿拉伊盆地位于特提斯构造带北缘,是在古生界基底之上发展起来的山间盆地,紧邻我国西部塔里木盆地。自中生代至新生代经历了陆表海沉积期、类前陆盆地期、山间盆地发育期、拗陷期、定形期等5个演化阶段,具有海陆交互、沉积多变、多期叠加、断-拗转换的性质。生储盖匹配良好;烃源岩为古近系、白垩系和中—下侏罗统的海相与潟湖相泥岩、石灰岩和泥灰岩;主要油气储集层为碳酸盐岩裂缝性储层和砂砾岩储层;多套泥岩、膏岩和泥灰岩为区域性和局部盖层;褶皱构造发育,以背斜、断块、断鼻等构造为主。盆地具有一定的油气勘探前景。  相似文献   

基于应变积累释放模型研究鄂尔多斯块体地震活动特征     

高立新  张晖  戴勇 《地震工程学报》2013,35(S1):54-60

利用1970年以来积累的仪器记录地震目录资料,基于G-R关系的应变积累释放模型,研究了鄂尔多斯块体周缘的应变积累释放分期特征及其所处的应变状态。结果表明,块体周缘的应变积累释放具有明显的两阶段分期特征,其周缘整体的应变释放和积累的分界线大致在公元2000年左右。块体周缘以及块体北缘、东缘、西缘目前均处于应变积累状态,应变积累时间均超过10年,未来将进入应变释放阶段,应变释放强度最大的为块体北缘、其次是块体的东缘和西缘;释放的应变量分别相当于6.5级和6.0级左右地震强度。南缘仍处于应变积累释放的起伏阶段。  相似文献   

波斯湾盆地的叠合演化与油气资源分布          下载免费PDF全文

王学军  赵玉光 《地质科学》2012,(4):1223-1237

波斯湾盆地是世界著名的富油气盆地,同时也是受多期构造演化控制的叠合盆地,通过地质与地球物理资料分析,认为盆地经历了前寒武纪-石炭纪陆内断陷盆地沉积与反转、二叠纪-中白垩世新特提斯被动陆缘盆地沉积和晚白垩世-新生代前陆盆地沉积演化3大演化阶段。断陷盆地演化阶段受近南北向陡直断裂控制,以碎屑岩和膏盐岩和碳酸盐岩建造为特征,碎屑岩在该阶段最为发育。被动陆缘盆地演化和前陆盆地演化阶段以碳酸盐岩和膏盐岩建造为主要特征。盆地叠合演化形成了前寒武系-下寒武统、志留系、侏罗系以及中下白垩统等多套富含有机质的烃源岩,与盆地内叠合联片发育的前寒武系-下寒武统、上二叠统、下三叠统、上侏罗统和中新统等多套膏盐岩构成了盆地内最佳的源盖组合,成为盆地油气富集的基础。每套优质的盖层之下都发育了一套优质的储层,并与构造作用形成的圈闭形成了盆地良好的储-圈组合,成为油气富集的必要条件。勘探成果显示,盆地西北部以断褶构造圈闭为主要特征,东北部以盐构造和断褶构造圈闭为特征,前陆斜坡区则以大型古隆起控制的圈闭为特征,盆地油气具有自山前带向斜坡区,含油气层位逐渐变老的特征。因此,对盆地的油气勘探,在不同的地区要区别对待。  相似文献