孟加拉国孟加拉盆地油气勘探潜力分析

孟加拉国位于南亚次大陆,是该地区重要的产气区。孟加拉盆地覆盖了该国绝大多数的领土,近年该盆地勘探力度不断加大,陆续有新的发现。据现有资料分析,该盆地有两个有效的生烃灶,其中渐新统Jenam组烃源岩主要分布于东部Surma坳陷,中新统Bhuban组烃源岩成熟区主要位于Hatia坳陷北部,处于低成熟阶段,供烃有限。平面上,油气分布明显受控于这两套烃源岩和圈闭的展布;纵向上,油气主要富集于东部前渊带的中新统储层。综合分析,孟加拉国孟加拉盆地有利勘探区位于前渊带东部,中新统储层仍是下一步勘探的热点和重点。     

北黄海盆地东部坳陷成藏要素及其作用研究

北黄海盆地东部坳陷是该盆地油气资源最为丰富的区域,朝鲜已在盆地东部发现油气,而我国至今尚未获得实质性突破。勘探资料证实,北黄海盆地东部坳陷发育3套烃源岩,上侏罗统为主要烃源岩,其次是古近系和下白垩统。存在中生界侏罗系-白垩系含油气系统,烃源岩为上侏罗统,下白垩统砂岩为主要储层,下白垩统和古近系泥岩为区域盖层,关键时刻为始新世末。分析认为东部坳陷最有希望的油气勘探层系在下白垩统,其次为古近系和上侏罗统。     

台湾海峡盆地油气地质条件与含油气系统研究

台湾海峡盆地是位于台湾海峡及其相邻台湾西部的中、新生代叠合盆地。油气地质研究表明,烃源岩主要为古新统及始新统潮坪—澙湖相泥岩和中新统海陆过渡相炭质泥岩和海相泥岩,储层为古新统、始新统的潮下坪相砂岩及中新统三角洲相砂岩,区域盖层为中新统—第四系泥岩。东部坳陷和西部坳陷的油气地质条件存在明显的差异。含油气系统研究认为,台湾海峡盆地发育了古近系和中新统两套含油气系统,盆地西部主要发育古近系含油气系统,具有较好的油气资源前景;盆地东部主要发育中新统含油气系统,具有良好的油气资源前景。      

东海陆架盆地中新生代构造演化对烃源岩分布的控制作用

东海陆架盆地为发育于克拉通基底之上的中、新生代叠合盆地,该盆地经历了晚三叠世(?)—中侏罗世克拉通边缘坳陷盆地、白垩纪弧前盆地和晚白垩世末—新生代弧后裂陷盆地等3个构造演化阶段。侏罗纪盆地和白垩纪盆地主要残留在中央隆起带;新生代盆地演化在平面上表现出裂陷由西向东迁移的特征。不同时代盆地构造类型和大地构造位置控制了盆地烃源岩发育层位及平面分布:西部坳陷带以古新统月桂峰组湖相泥岩和灵峰组、明月峰组滨海相煤系地层为主要烃源岩;中央隆起带以上三叠统—中侏罗统福州组为主要烃源岩;东部坳陷带以始新统平湖组煤系地层为主要烃源岩,渐新统和中新统煤系地层为次要烃源岩。西湖凹陷天台斜坡带为中、新生代有利烃源岩的叠合区,具有“中生中储”和“新生中储”的优势,是东海陆架盆地天然气勘探的有利地区。     

北黄海盆地东部坳陷油气成藏时间研究

东部坳陷是北黄海盆地唯一发现油流的沉积坳陷,具有较好的油气勘探前景,其油气藏形成时间将决定该区油气勘探思路和油气勘探方向。通过烃源岩的油气生排烃史和油层的砂岩包裹体研究,综合分析推断了东部坳陷油气藏成藏时间。研究表明,东部坳陷中侏罗统烃源岩的主要生烃期和排烃期为渐新世,下白垩统和上侏罗统砂岩储层包裹体的油充注时间为早中新世。结合盆地构造演化史综合分析推断,北黄海盆地东部坳陷的油气藏形成时间为晚渐新世至早中新世。     

北萨哈林盆地油气成藏主控因素及有利区带分析

北萨哈林盆地属于中新生代弧后盆地,发育中、上中新统奥科贝凯组页岩、上中新统努托瓦组下段页岩、下中新统威宁组和中、下中新统达吉组含煤层系3套烃源岩。主力产层为中、下中新统的达吉组砂岩和上中新统努托瓦组下段砂岩。圈闭类型为背斜、复杂断背斜和断块。统计分析表明,平面上油气主要聚集在盆地东北萨哈林次盆,并且海上油气储量、油气田规模均大于陆上;垂向上油气主要分布在中新统达吉组和上中新统努托瓦组。油气成藏条件综合评价分析认为,盆地油气分布主要受构造和储层两方面因素的控制:上新世晚期形成的构造圈闭是油气聚集的主要场所,上新世晚期—全新世萨哈林褶皱幕对早期形成的圈闭起调整或破坏作用;中、下中新统达吉组和上中新统努托瓦组下段砂岩的展布控制了油气藏的纵横向分布。油气勘探结果表明,东北萨哈林次盆陆上部分勘探程度较高,海上是近几年的储量增长区,也是今后最具勘探潜力的地区,其勘探目的层主要为努托瓦组和达吉组,勘探目标主要为构造—地层型圈闭和地层型圈闭。     

南海北部陆缘盆地深水区油气勘探前景

南海北部陆缘盆地深水区位于琼东南盆地中央坳陷带和珠江口盆地珠二坳陷,从盆地演化史来看,两盆地均经历了裂陷和裂后两大发育阶段。南海北部陆缘盆地深水区具有良好的石油地质条件：发育始新统一渐新统湖相泥岩和渐新统半封闭浅海相泥岩两套主要烃源岩;存在始新统一下渐新统河流一三角洲相砂岩、上渐新统一下中新统扇三角洲一滨浅海相砂岩和台地碳酸盐岩以及中新统半深海一深海相浊积砂岩等3套主要储层,其中中新统半深海一深海相浊积砂岩储层是深水区员有潜力的勘探目的层,发育多种类型的圈闭,从层位上看,下第三系以构造田闭为主,而上第三系则以岩性圈闭为主,发育大量油源断层、多个不整合面和大面积连通砂体,构成了良好的油气输导体系,有利于油气聚集成藏。与国外已获油气发现的陆缘盆地深水区相比,南海北部陆缘盆地深水区具有相似的构造、沉积演化特征和相应的成油条件,目前南海北部深水区勘探程度尚低,有效勘探面积和勘探潜力巨大,因此具有良好的勘探前景。     

阿根廷圣豪尔赫盆地油气成藏特征及有利区预测

圣豪尔赫盆地是阿根廷重要的产油气盆地之一,其演化经历了4个阶段,形成三叠纪—早白垩世裂谷和早白垩世—新生代坳陷双层结构。从区域构造沉积演化入手,结合最新钻井资料,对盆地油气成藏特征及控制因素分析后指出,烃源岩主要为上侏罗统—下白垩统Neocomian群和下白垩统D-129组湖相页岩;主要储层为白垩系Chubut群砂岩;Chubut群内的湖相泥页岩构成最重要的盖层;断、拗以及安第斯造山运动形成了丰富的圈闭类型。成熟烃源岩的分布与断裂体系控制油气的富集;河流相砂体控制油气藏规模;油气主要围绕盆地中心呈环带状分布。在此基础上,预测了白垩系Chubut群上部砂岩、白垩系D-129组与上侏罗统—下白垩统Neocomian群的勘探有利区。     

东海陆架盆地基隆凹陷构造演化特征及勘探前景

基隆凹陷是东海陆架盆地主要沉积凹陷,凹陷构造演化经历了断陷、断坳、坳陷和被覆四个阶段。凹陷由西部缓坡断阶带、中央洼陷带和东部陡坡带组成,主要填充新生界沉积层系。始新统至中新统发育四套烃源岩,油气主要储存于始新统、渐新统和中新统地层中,存在四套有利油气成藏组合。2005年油气资源评价,西湖凹陷油气当量为15.6亿方,西湖与基隆凹陷为一个统一凹陷,只是在晚渐新世-早中新世时期被短暂分隔,石油地质条件应基本相同。油气地质分析表明基隆凹陷具有良好勘探前景,凹陷西部缓坡断阶带油气勘探潜力最大。     

澳大利亚布劳斯盆地构造地质特征及勘探潜力

布劳斯盆地是澳大利亚西北陆架主要含油气盆地之一,盆地演化经历了裂前坳陷、裂谷、过渡-漂移和裂后被动大陆边缘4个发育阶段,主要充填了中生界沉积地层。二叠系-下白垩统发育4套烃源岩,油气主要储集在侏罗系和下白垩统地层。区域上,石油分布在Caswell次盆外带,纵向上主要分布在下白垩统;Caswell次盆内带则富集了大部分的天然气和凝析油。截至2005年,盆地内已发现石油(包括凝析油)可采储量3.45×108bbl,天然气7241×108m3。油气地质综合分析表明,该盆地具有良好的勘探前景,勘探程度较低的Caswell次盆西部枢纽带、中部隆起带和东部断阶带勘探潜力最大。     

SOURCE ROCK POTENTIAL OF ORGANIC‐RICH SHALES IN THE TERTIARY BHUBAN AND BOKA BIL FORMATIONS,BENGAL BASIN,BANGLADESH

Sandstones in the Miocene Bhuban and Lower Pliocene Boka Bil Formations contain all of the hydrocarbons so far discovered in the Bengal Basin, Bangladesh. Organic‐rich shale intervals in these formations have source rock potential and are the focus of the present study which is based on an analysis of 36 core samples from wells in eight gasfields in the eastern Bengal Basin. Kerogen facies and thermal maturity of these shales were studied using standard organic geochemical and organic petrographic techniques. Organic matter is dominated by Type III kerogen with lesser amounts of Type II. TOC is 0.16–0.90 wt % (Bhuban Formation) and 0.15–0.55 wt % (Boka Bil Formation) and extractable organic matter (EOM) is 132–2814 ppm and 235–1458 ppm, respectively. The hydrogen index is 20–181 mg HC/g TOC in the Bhuban shales and 35–282 mg HC/ g TOC in the Boka Bil shales. Vitrinite was the dominant maceral group observed followed by liptinite and inertinite. Gas chromatographic parameters including the C/S ratio, n‐alkane CPI, Pr/Ph ratio, hopane Ts/Tm ratio and sterane distribution suggest that the organic matter in both formations is mainly derived from terrestrial sources deposited in conditions which alternated between oxic and sub‐oxic. The geochemical and petrographic results suggest that the shales analysed can be ranked as poor to fair gas‐prone source rocks. The maturity of the samples varies, and vitrinite reflectance ranges from 0.48 to 0.76 %VR_r. Geochemical parameters support a maturity range from just pre‐ oil window to mid‐ oil window.     

四川盆地上三叠统深盆气藏研究

川西前陆盆地的盆地演化、盆地结构和相对稳定的斜坡构造有利于深盆气的形成和聚集.上三叠统为海陆过渡相和陆相湖盆沉积,以三角洲沉积为主的砂体十分发育,晚侏罗世中期至早白垩世末期储层开始致密化,早白垩世以后储层进入超致密阶段,但对于深盆气仍是十分有效的储层.砂体的上覆和下伏层均为暗色泥岩夹薄煤层的气源岩,因此对深盆气的聚集和富集成藏十分有利.煤系气源岩分布广、厚度大、生气潜力高、热演化程度高,从而为川西坳陷深盆气的形成提供了充足的气源.在早白垩世-晚白垩世中期,源岩进入生气高峰,为深盆气形成的重要时期,造成孔隙中流体体积急剧膨胀,引起川西区处于超压环境.喜山运动后盆地大范围仍处于水动力交替停滞带,上三叠统深盆气藏大面积具有整体封存条件.因此,上三叠统形成了一个几乎覆盖全盆地的特大型深盆气藏.通过对深盆气藏的主控地质因素的分析,可将川西坳陷划分为深盆气分布区、气水过渡带和上倾含水区(常规气藏分布区)等三个区带.从全盆地看,气水分布具有明显的倒置关系,深盆区内气水分布不受构造控制.     

GEOPHYSICAL CHARACTERIZATION OF THE SANGU GAS FIELD,OFFSHORE, BANGLADESH: CONSTRAINTS ON RESERVOIRS

The only produced offshore gas field in Bangladesh, known as the Sangu field, is located in the Hatiya Trough in the east of the Bay of Bengal, and has estimated total reserves of about 1055 BCF GIIP. The early shut-down of the field in October 2013 may have resulted in significant volumes of recoverable gas being left in the subsurface over a depth range of 1893 m to 3640 m. In this paper, seismic and well log data were analyzed and interpreted in order to investigate the structure and stratigraphy of the Sangu field, together with the lithology, extent and petrophysical properties of the reservoir. The general lithostratigraphy at Sangu has some similarity to that of the Surma Basin of the Bengal Foredeep. Reservoir rocks consist of Miocene and Pliocene deltaic sandstones and deep-water clastics. The source rock is the Miocene Bhuban Shale which is mature for gas generation in the Hatiya Trough. Three Neogene seismic stratigraphic megasequences were recognised at Sangu and are interpreted to have been deposited respectively in fluvial, delta front and shelf slope or marginal marine settings. Based on an analysis of wireline logs from wells Sangu-1 and Sangu-5 and on seismic-to-well ties, a series of reservoir units referred to (from the base up) as the T1 (E, D, C, A&B), Supra-T1, T2 and T3 have been identified. Petrophysical analyses showed that the average total porosity of these reservoir units is >13%, the permeability is in general less than10 mD, and the gas saturation ranges from 24% to 80%. Mapping of the reservoirs shows that the structure at Sangu is an asymmetric anticline with a NNW-SSE axial trend. Amplitude data have allowed the delineation of two other potential reservoir zones in the field at depths of 2900-3000 m and 3550-3750 m. The study will contribute to future offshore gas exploration and development in the Bay of Bengal region based on the geological and geophysical characteristics of the reservoirs delineated.     

East Venezuela盆地油气聚集与勘探潜力

East Venezuela盆地是一个大型的不对称前陆盆地,具有丰富油气资源。古生代以来,经历了晚三叠世—侏罗纪裂谷、白垩纪—始新世被动边缘和渐新世至今前陆盆地3个演化阶段。纵向上沉积地层可划分为前白垩系、白垩系和后白垩系3套巨层序。East Venezuela盆地最主要的烃源岩是Guayuta群和Tigre组海相泥页岩和碳酸盐岩。生油岩成熟度由北往南递减。北部烃源灶油气经断层、砂体长距离阶梯式向南部斜坡边缘运移。盆地最主要圈闭类型为背斜、断块、地层和岩性圈闭。Oficina组构造、构造—地层、地层圈闭组合和Naricual组构造圈闭组合是盆地内最主要的两套成藏组合。有潜力的勘探领域包括白垩系—下中新统被动边缘沉积层序、盆地中部前渊区、南部重油带和东部海域。     

OIL AND GAS PLAYS IN ALBANIA: DO EQUIVALENT PLAYS EXIST IN GREECE?

Western Greece and Albania have had a broadly similar geological history and the hydrocarbon potentials of both areas may therefore be comparable. In this paper, we briefly review the stratigraphic and structural evolution of Albania and compare it with that of NW Greece in terms of source rocks, reservoirs, seals, structures and maturation history.
In Albania, a number of sizeable oilfields produce from Mesozoic-Paleogene carbonates assigned to the Ionian Zone; traps are thrust-related anticlines. Gas is produced from both Mesozoic reservoir rocks and also from Tortonian-Messinian sandstones along the eastern margin of the Neogene Durres Basin. In both Albania and western Greece, the Mesozoic to Eocene succession includes organic-rich shales which were deposited on the Apulian margin of the Pindos Ocean. Tertiary closure of that ocean resulted in thin-skinned thrusting onto the Apulian margin along Triassic evaporite décollements. Thick, late Eocene to Miocene flysch was deposited synchronously in the Pindos foreland basin, and was deformed by the advancing thrust system.
The Neogene Durres and Preveza Basins developed on the Apulian foreland as a result of complex plate-tectonic interactions and block rotations. NE-trending lineaments played an important role in the evolution of these basins, and also gave rise to dip-closed anticlines in the Ionian Zone successions in both countries. In Albania, the Vlora-Elbasan lineament controlled the development of structural traps at producing oilfields, and the Cephalonia transform fault in Greece may have played an analogous structural role. Potential hydrocarbon plays in NW Greece, analogous to producing fields in Albania, are located in the Ionian thrust belt and in the Neogene Preveza Basin. In addition, the middle Tertiary flysch basins of both countries may have some gas potential.     

鄂尔多斯盆地北部晚古生代的深盆气气藏

鄂尔多斯盆地晚古生代整体抬升,形成了稳定的大型区域斜坡,为深盆气的形成提供了必要的构造条件;其太原组、山西组煤系地层具有良好的生气条件,为深盆气的形成奠定了物质基础;太原组、山西组及下石盒子组的砂体厚度大、分布广,且岩性致密,为深盆气的形成起到了决定性作用。深盆气藏在伊陕斜坡及天环凹陷一带以产气为主;晋西断褶带至西缘断褶带气水同产;在伊 12井至哈 2井一带则以产水为主。伊陕斜坡及天环凹陷的主体均处于深盆气藏的含气带内,储量丰度高,是最具远景的勘探区域。     

试论中国近海两个坳陷带油气地质差异性

中国近海辽阔的海域蕴藏了丰富的油气资源,历经40年的勘探取得了丰硕的成果。限于技术、资料和研究深度,多年来人们一直认为中国近海诸盆地的类型、油气地质条件相似,属于大陆边缘的新生代断陷(裂谷)盆地。但是,对大量地震、钻井资料的分析表明,中国近海存在两个坳陷带,这两个坳陷带的构造位置、地温梯度、盆地类型、形成时期、沉积环境、油气地质条件、油气性质等明显不同。第一坳陷带包括渤海湾盆地、南黄海盆地、台北坳陷、珠一坳陷、珠三坳陷和北部湾盆地,是位于陆壳上的湖相断陷(裂谷)盆地,以生油为主。第二坳陷带包括浙东坳陷、珠二坳陷、琼东南盆地和莺歌海盆地,是陆—洋过渡壳上的海相坳陷盆地,以生气为主。第一坳陷带已经成为重要的产油区,预测第二坳陷带将会成为中国海上的大气区。     

IN‐RESERVOIR FRACTIONATION AND THE ACCUMULATION OF OIL AND CONDENSATES IN THE SURMA BASIN,NE BANGLADESH

Petroleum in the Surma basin, NE Bangladesh (part of the Bengal Basin) ranges from waxy crude oils to condensates. The origin and source rocks of these hydrocarbons were investigated based on the distributions of saturated and aromatic hydrocarbons in 20 oil samples from seven oil and gas fields. The relative compositions of pristane, phytane and adjacent n‐alkanes suggest that the source rock was deposited in a non‐marine setting. The abundance and similar distribution of biphenyls, cadalene and bicadinanes in most of the crude oils and condensates indicates a significant supply of higher‐plant derived organic matter to the source rocks. Maturity levels of the crude oils and condensates from the Surma basin correspond to calculated vitrinite reflectance (R_c) values of 1.0–1.3%, indicating hydrocarbon expulsion from the source rock at a comparatively high maturity level. The R_c values of oils from the Titas field in the southern margin of the Surma basin are relatively low (0.8–1.0%). Some oils were severely biodegraded. The similar distribution of diamondoid hydrocarbons in both biodegraded and non‐biodegraded oils indicated similar types of source rocks and similar maturity levels to those of oils from the Surma basin. The Oligocene Jenam Shale and/or underlying non‐marine deposits located at greater depths may be potential source rocks. The diversity of the petroleum in the Surma basin was likely due to evaporative fractionation, resulting in residual waxy oils and lighter condensates which subsequently underwent tertiary migration and re‐accumulation. Evaporative fractionation due to modification of the reservoir structure occurred during and after the Pliocene, when large‐scale tectonic deformation occurred in and around the Bengal Basin.     

全球生物气藏分布特征及成藏条件

为了明确未来大型生物气藏的勘探方向,通过对全球18个重点生物气藏发育区的基本情况和其中14个早期生物成因的原生型常规生物气藏发育区油气地质条件的统计,分析探讨了原生型生物气藏分布特征及其与成藏要素的关系,归纳总结了大型原生型生物气藏形成的宏观地质条件。研究结果表明:①生物气藏储量分布具有储层时代新、埋藏偏浅、深水超深水的残余洋盆地为主的分布特征;②全球超过70%储量的早期生物成因的原生型常规生物气藏分布在具有低地表(海底)温度、低地温梯度条件、与古三角洲河口区和水下扇特别是大型深水扇相关的沉积环境中;③上述地区发育的巨厚砂泥岩具有较高的沉积速率和较低的砂地比,形成了一定丰度的(TOC 0.5%)、以腐殖型有机质为主的烃源岩层系,既可以为微生物提供长时间、大厚度范围活动空间和养分,同时对生物气的散失也可以起到抑制作用。结论认为,未来的大型生物气藏的勘探方向应集中在具有低地表(海底)温度的冻土区和深水区、低地温梯度类型的盆地、古三角洲河口区—水下扇相关沉积环境、构造活动强度适中的正向构造带的四要素叠合领域:①具有大型物源基础的被动大陆边缘盆地外带深水区,如南大西洋两岸的尼日尔三角洲盆地深水、刚果扇、亚马逊扇以及一些古三角洲发育区;②具有大型水下扇的残余洋盆地,如孟加拉扇、印度河扇等;③具有深前渊特征前陆盆地的前渊区,如巴布亚盆地东部前渊;④冻土地区的克拉通盆地内坳陷区。