塔里木盆地早古生代晚期构造-沉积响应

伴随相对海平面由上升转为下降的周期变化,塔里木盆地在早古生代经历了一次大规模的扩张→挤压→隆升的开合旋回,早期(震旦纪-中奥陶世)处于拉张的构造背景下,呈现西台(碳酸盐台地)东盆(满加尔-库鲁克塔格深水盆地)的古地理格局。中西部广大地区沉积了巨厚的浅水台地相碳酸盐岩,以中晚寒武世的下丘里塔格群和早中奥陶世的上丘里塔格群为标志;东部的满加尔-库鲁克塔格则以厚度不大的远洋硅-灰泥沉积为主。盆地构造性质的转换及沉积古地理的巨大改变发生于中奥陶世中晚期,以塔中、塔北的隆起和塘古孜巴斯坳陷及阿瓦提-满加尔坳陷的形成为标志,呈近南北向隆-坳相间的盆地格局。沉积记录的响应表现为碳酸盐台地的消失、陆源物质的逐渐注入和向上变粗、火山活动和火山碎屑的出现以及巨厚砂泥质浊积岩在塔东盆地内的充填等。因此,中晚奥陶世-中泥盆世是塔里木盆地海域逐渐萎缩、盆地不断隆升和相对海平面逐渐下降的一个过程。     

中国海相油气田勘探实例之五塔中奥陶系大型凝析气田的勘探和发现

塔中奥陶系碳酸盐岩的勘探始于1989年,直至2005年发现塔中Ⅰ号坡折带奥陶系碳酸盐岩凝析气田,探明加控制石油地质储量1.5×108t(油当量),是我国目前发现的第一个奥陶系生物礁型大油气田。油气的主力产层位于上奥陶统良里塔格组上部,储层为受坡折带控制的陆棚边缘礁滩体石灰岩。油气沿坡折带呈带状展布,为整体含油的大型准层状岩性油气藏。论述了塔中碳酸盐岩大油气田的勘探历程、主要地质特征,以及对海相碳酸盐岩勘探的启示。     

Basin-scale structure control of Carlin-style gold deposits in central Southwestern Guizhou,China: Insights from seismic reflection profiles and gravity data

Carlin-style gold deposits are widely distributed in Southwestern Guizhou, China. Research has dominantly focused on deposit-scale geology and structural control of mineralization. The relationship between the gold deposits and regional structures, in particular their control on the formation and distribution of those deposits is less well understood. Here we use seismic survey and gravity data to reveal the basin-scale structure control of the gold deposits in central Southwestern Guizhou. The seismic reflection profiles show strong reflection horizons including Upper Permian coal measures, and Dongwu and Guangxi unconformities. The seismic data provide important evidence of the basinal structural style and the relationship between fault-related folding and the Carlin-style gold deposits. Regional gravity data also revealed several paleo-uplifts, which appear to control the distribution of Carlin-style gold deposits.The Carlin-style gold deposits are spatially and temporally associated with fault-related folds. Based on their location, we classify the gold deposits into two types, (1) low-angle thrust-controlled deposits; and (2) high-angle reverse fault-related deposits. In the low-angle thrust-controlled deposits, main thrusts are listric, strike NW-SE and dip southwest. These thrusts detach into coal measures, tuffs and volcanic rocks and are bedding-parallel in the vicinity of the Dongwu unconformity. Gold ore bodies are found in the thrusts and characterized by cutting-layer veins near the surface and bedding-parallel veins at depth. The high-angle reverse fault-related deposits are located in the hinge of northeast-southwest-striking fault-related folds, with high-angle reverse faults near the hinge of folds crosscutting the Upper Permian coal measures, volcanic rocks and Dongwu unconformity, and then into the limestone of Middle Permian Maokou Formation. Ore bodies are bedding-parallel in anticline culminations where interlayer fracture zones in Upper Permian coal measures and volcanic rocks are generated by high-angle reverse faulting.We consider that the formation of the gold deposits is part of the tectonic evolution in the area. The two sets of NW-SE- and NE-SW-striking fault-related folds were successively formed during the closure of eastern Tethys Ocean in Late Triassic, and major gold deposits formed in the fault-related folds. The Dongwu unconformity and faults provided conduits for ore fluid flow, and the coal measures and the tuffs of Dachang Member acted as detachment layers and hosts for ore deposition.     

准噶尔腹部火山岩风化壳储层特征及其影响因素

文章通过大量岩芯、铸体薄片观察和测井资料分析,对准噶尔腹部石西石炭系火山岩风化壳储层进行了详细地研究。研究结果表明,该火山岩风化壳储层的储集空间主要有基质溶孔、气孔或杏仁体溶孔、角砾间溶孔、微裂缝和裂缝等,其中与裂缝连通的各类溶孔占主导地位;在岩石分布上以集块岩、条带状熔岩、角砾熔岩和致密凝灰岩为主,玄武岩、安山岩和流纹岩则相对较少;储层物性主要表现为高孔低渗,只有裂缝具有较高的渗透率,且裂缝以高角度缝和直立缝为主。研究还发现,岩性岩相、裂缝和风化淋滤作用是影响该风化壳储层的主要因素。区内油层主要聚中在构造高部位、靠近断裂带和有利岩相区域;油层分布在离石炭系风化壳顶面25~150 m的范围内。     

Sinian-Cambrian Tectonic Framework in the Tarim Basin and its Influences on the Paleogeography of the Early CambrianEI北大核心CSCD

Due to strong remodification and sparse trace remnants, tectonic restoration is critical for the reconstructing of the paleography and basin-prototype in the multiple-cycles superimposed basin, which is also fundamental for the hydrocarbon exploration of the deep marine carbonate in the Tarim Basin. This study presents the tectonic framework of the transition phase from the Sinian to the Cambrian Period and its constrains on the paleography of the Cambrian in the Tarim Basin based on comprehensive analysis of new geochronology data, seismic data and regional tectonic data. The results showed that (1) there is a large regional unconformity between the Cambrian and Precambrian, suggesting a discontinuous deposition from the Sinian to the Cambrian that is contrary to the major view; (2) a broad flattened paleotopography formed before Cambrian Period, which is favorable for the wide epicontinental sea environment and a gentle homoclinal ramp platform development in the early Cambrian, and the residual basement low relief uplifts that influence the microfacies differentiation in the carbonate platform; (3) the Cambrian carbonate platform has been involved much into the marginal orogenic belts, and the proto-platform is probably of 200 km out of the present basin in S-N direction; (4) there is a weak extensional setting in the Cambrian-Early Ordovician rather than a strong rifting setting with a large aulacogen into the platform, in which a inter-platform shallow depression and stable ramp platform developed in the Cambrian; (5) there is not troughs, but rather low relief uplifts developed in the Early Cambrian in the southwestern Tarim Basin, and lack of large uplifts along the carbonate platform margins; (6) it is showed a broad architecture of platform-wide slope-ocean basin from the inner Tarim plate to its margin in the Cambrian Period. Considering the basin prototype, the restoration of the tectono-paleography in the early Cambrian in the Tarim Basin is distinct from those of the previously proposed. We propose that a gentle pattern with “two platforms and one inter-depression” in E-W striking other than multiple small platform constrained in the basin, and further subdivision of the western platform with inner platform low uplift and sag in N-S striking, which is possibly inherited from the basement architecture. On the outer of the united platform, there is probably broad gentle slope for transition to ocean basin. We therefore argue that tectonic restoration is crucial for reconstruction of the paleogeography and basin prototype, especially for basins experienced multiphase of tectonic cycles. © 2018, Science Press. All right reserved.     

THE FINDINGS OF THE UPPER PERMIAN IN THE CUOQIN BASIN, TIBET

THE FINDINGS OF THE UPPER PERMIAN IN THE CUOQIN BASIN, TIBET     

越南兰龙盆地白虎油田储集层特征及成藏模式探讨

基于岩心、钻测井、三维地震和沉积相资料,对越南兰龙盆地白虎油田的碎屑岩、基岩储集层特征以及对应的两种成藏模式进行综合分析。结果表明,白虎油田发育两类岩性储集层,即碎屑岩(砂岩)、花岗岩基岩储集层,其中碎屑岩储层在兰龙盆地基底地垒构造格架下沉积,受大地构造运动、海平面变化控制,以冲积扇、扇三角洲和河流相为主,在渐新统泥岩供烃的条件下形成了具有自生自储、下生上储特征的岩性、构造油藏。花岗岩的基岩裂缝、孔洞发育,具备优势的储集空间、储层规模大,成为最主力的储集层,成因为基底演化过程中的断裂活动、热液岩熔等作用。在花岗岩基岩储层中形成了两种成藏模式：一种以花岗岩无机成因自身含烃表现出原地成藏的特征;另一种上覆渐新统泥岩为富油烃源岩,沿断层、不整合面等侧向运移至基底顶部晚期聚集成藏,最终在基底中广泛发育裂缝、缝洞型基岩油藏。     

海-塔盆地中部断陷带南屯组沉积体系配置及有利相带分析

本文充分利用岩芯、测井、地震及分析化验等资料,对海-塔盆地中部断陷带4个主力凹陷的南屯组砂体类型及分布特征进行了详细研究。结果表明,南屯组主要发育扇三角洲、近岸水下扇、辫状河三角洲和湖底扇等4种典型类型砂体,并从沉积背景、发育部位、沉积特征、搬运机制以及地震反射特征等5个方面,分不同角度、不同层次详细阐述了扇三角洲、近岸水下扇、辫状河三角洲和湖底扇的识别标志;其中扇三角洲主要分布在乌尔逊凹陷和贝尔凹陷的陡坡带,近岸水下扇主要分布在南贝尔凹陷和塔南凹陷的陡坡带,而辫状河三角洲主要分布乌尔逊凹陷、贝尔凹陷和南贝尔凹陷的缓坡带。从盆地边部向盆地中心方向,沉积相由扇三角洲、近岸水下扇和辫状河三角洲沉积逐渐过渡为半深湖-深湖相沉积,局部半深湖-深湖相中发育湖底扇沉积体系,整体具有“南北分块、东西分带”的沉积格局。综合研究表明,扇三角洲前缘、近岸水下扇中扇和辫状河三角洲前缘砂体是油气富集的有利沉积相带,而洼槽边缘的湖底扇砂体为岩性油气藏勘探的重点对象。     

松辽盆地东缘营城组节理构造特征、分布规律及其储层预测

首次较系统地统计了研究区节理产状、规模、开度、密度以及分布规律,阐述了其储层意义。根据节理产出层位、切割关系和区域构造背景分析,将研究区节理的形成期次划分为营城期、营城末期和晚白垩世晚期3个期次。利用共轭节理产状和节理面性质,计算出营城期具有近东西向伸展和挤压相互交替的构造应力场;营城组末期具有NE—SW向挤压构造应力场;晚白垩世晚期具有NW—SE向挤压构造应力场。营城组中的节理形成与分布主要与前两期挤压应力场有关。在此基础上,对徐家围子地区营城组节理分布规律进行了预测,为天然气储层分布规律研究提供可视化对比依据。     

柴达木盆地三湖坳陷第四系重矿物物源分析

岩性圈闭作为三湖坳陷下一步勘探的主要对象,明确物源区及各源区对坳陷内部的影响范围是首要任务。依照 重矿物“相关性分析定母岩类型、因子分析定物源主次、Q聚类分析定影响范围、稳定系数分析定物源方向”的研究思路,综合分析研究区内所有重矿物数据的数理统计特征,发现工区母岩类型主要为变质岩、中基性喷出岩和少量沉积岩,分别对应南部昆仑山主要物源、东北埃姆尼克山次要物源和北部祁连山弱物源。南部物源主要控制南斜坡区沉积,但其中西南昆仑山-那北分支物源影响范围可达北斜坡台南-涩北气田一带;东北物源对坳陷内部影响范围局限在盐湖、哑叭尔及察尔汗一带;北部物源对区内沉积起微弱作用。