【作者】 陈旭；

【导师】 陈红汉； 王家豪；

【作者基本信息】 中国地质大学 ， 能源地质工程， 2011， 硕士

【摘要】 塔里木盆地是我国西气东输的主要能源基地,油气资源十分丰富,资源量超过100×108t,被地质学家称为我国油气工业的“希望之海”。三叠系碎屑岩储层作为主要勘探目标之一,多年勘探实践已在塔河-轮南地区取得了显著的勘探成效,同时阿瓦提断陷西北部地区发现了良好的油气显示,总体显示了巨大的勘探潜力。前人对盆地内不同构造单元(尤其在塔北地区)的三叠系沉积相及层序地层特征进行过研究,然而因受资料限制、研究范围不同及采用的层序地层理论学派不同,导致前人对台盆区三叠系层序地层研究程度及认识差异较大,迄今还未建立比较认可的、贯穿全区的层序划分方案。同时对盆地沉积相类型、平面展布、充填演化及储集砂体展布的研究也较薄弱,从而制约了对三叠系有利勘探区带和油气富集规律的深入认识。针对以上存在问题,本文以经典层序地层学和现代沉积学理论为指导,把台盆区三叠系作为整体进行解剖,在研究区354条骨干地震测网、120多口钻测井资料、岩芯及大量分析化验等资料的基础上,从宏观的地震层序分析入手,依据盆地三级层序界面识别和内幕结构划分,采取局部与整体相结合,充分应用区域地震剖面进行全盆层序格架的整体解释,并在地震层序格架指导下进行井震标定,开展钻井层序的细分对比,并依据古生物标志,最终建立了台盆区统一的层序地层格架,统一了不同构造单元的地层划分方案,进一步总结研究区坳陷盆地特色的层序地层发育模式。在等时地层格架基础上,结合岩石类型、结构特征、沉积构造、测井相、地震相和物源供给系统分析等多种手段,系统分析台盆区各层序沉积相类型、发育特征、纵横向展布规律。最终应用于台盆区潜在的岩性地层圈闭类型和控制因素分析,并对重点区块有利勘探区带进行预测,从而为盆地三叠系整体的油气勘探部署提供依据。通过系统分析研究,本论文得到以下主要成果性认识：1.此次在台盆区自下而上识别出T48、T46a2、T46a1、T46h、T46等5个层序界面,将三叠系划分为T-SQ1-T-SQ4共4个三级层序。通过全区地震层序解释,将三叠系底界由此前T50变更为T48,同时重新厘定了三叠系柯吐尔组和二叠系沙井子组分界面。该界面在塔中地区大部单纯从岩性、颜色上难以区分。2.本次地震层序解释表明,虽然塔中和塔河地区三叠系地层组均采用了3分方案,塔河地区柯吐尔组与塔中地区三叠系下部均发育厚层泥岩,岩性组成上有着可比性,在层序格架上,塔中地区三叠系下部厚层泥岩为T-SQ1层序湖扩至高位体系域早期沉积；而塔河地区T-SQ1层序普遍缺失,柯吐尔组厚层泥岩为T-SQ2层序的湖扩至高位体系域早期沉积。总体上,塔中和塔河地区地层划分方案上呈错位对接关系。此前划分为岩石地层方案,明显存在穿时现象。3.对台盆区层序界面识别和典型内幕结构解析看来,层序低位、湖扩、高位体系域“三元”结构是毋庸置疑的。由于所处盆缘位置不同以及湖盆坡度十分宽缓的条件下,小的湖平面变化即能造成湖岸线的迁移距离远,低位体系域时期湖盆范围急剧萎缩,造成低位体系域分布范围小,厚度薄,普遍缺乏大型前积反射的特征结构,常常不发育低位扇体,另外,缓坡高部位常常缺失低位体系域。湖扩体系域呈现远距离的上超,高位体系域具波及范围广泛的平缓前积反射,与陆架坡折背景的发育低位扇、低位楔具高角度“S”型前积反射特征有所不同。台盆区作为前陆盆地系统的隆后盆地单元,其发育演化及层序结构受控于挤压挠曲作用过程。单个层序内沉降中心向北迁移以及多个层序沉降中心总体向北迁移的特征,即是层序受控于幕式挤压挠曲作用的具体体现。4.层序结构及内幕沉积演化方面,台盆区三叠纪湖盆坡缓水浅、沉积物供给丰富,总体表现为宽浅型坳陷湖盆背景下大型辫状河三角洲广泛发育的面貌,相应发育了辫状分流河道、水下分流河道、河口坝、远沙坝4种主要有利储集砂体类型。半深湖亚相仅在湖扩体系域时期发育,除此之外,大多为宽浅型滨浅湖-浅湖背景。三角洲平原上河道长距离向水下延伸,形成了特色的水下河道,外加台盆区湖平面变化幅度小、对沉积物供给的抑制作用小等原因,三角洲进积序列中先期堆积的河口沙坝较细粒沉积体,常因受向湖盆方向延伸的后期水下分流河道冲刷截切而保存不完整,并以水下分流河道砂体逐渐占优势,形成辫状河三角洲体系中以水下分流河道砂体为骨架砂体的重要特征,平面上整体表现为不断向盆地腹部推进的、相互叠置的大型三角洲复合体。最终,一个三级层序内部多表现为辫状河三角洲→滨浅湖→辫状河三角洲的退积→前积演化序列,辫状河三角洲在低位体系域、湖扩体系域早期以及高位体系域中晚期发育普遍,湖扩体系域中晚期至高位体系域早期则普遍由滨浅湖-半深湖厚层泥岩组成。5.鉴于三叠系储集砂体在台盆区广大地区极为发育、储集性能较好、分布较广、所形成的油气藏为次生油气藏、有利圈闭类型多为岩性—地层及构造—岩性复合圈闭等特征,认为台盆区油气成藏的关键应为是否具有效的输导及封堵遮挡条件。研究认为,塔北南部-顺托果勒北部斜坡部位,满西-顺托果勒西部斜坡部位和阿瓦提北部斜坡部位具有良好的勘探前景。更多还原

【Abstract】 Tarim Basin is an important energy basement for transporting nature gas from the west to the east. It has plenty of petreoleum resource that is more than 100×108 t, so Tarim Basin is known to geologists as the oil and gas industry’s hope. The Triassic is one of the most significant petroliferous strata..A series of oil and gas pool has been found in Triassic strata in Tahe-Lunnan area over the past few years, at well as good evidences of oil and gas have been acquired in the northwest of Awati aera. It is, therefore, showing a huge exploration potential.Although predecessors have researched the sedimentation and sequence stratigraphy in different tectonic units (especially in Tabei area), the basin wide sequence stratigraphy is researched little. However, due to data limitations, the study area and the use of different different theoretical of sequence stratigraphy, different people have quite different ideas on Triassic. Until now, authorized and trans- region sequence stratigraphic program has not been established. At the same time, because of the limited research on sedimentary facies,sedimentary system, filling evolution and sandbody distribution, the deep cognizance of oil accumulation was weak. Above all, the study of favorable exploration area and oil-gas accumulational regularity is restricted.To solve the above problems, the study is under the theoretical guidance of sequence stratigraphy, contemporary sedimentology, petroleum geology and geophysics, and the overall research of the whole basin is emphasized. We analyzed the 354 seismic data, more than 120 logging and drilling core data of Triassic in Tarim Basin. From a macro seismic sequence analysis, depending on the identification of sequence and system tract boundaries, combining the part and whole of the basin, fully using the regional basin-wide seismic interpretation, carrying out the meticulous comparisonby of drilling sequence in the basement of synthetic demarcation, and combining the palaeontologic marker, a unified sequence stratigraphic framework between well and seismic is established in platform area, and a stratigraphic program in different tectonic units is unified. To the further, the sequence stratigraphic characteristics and models of the depression basin in study area is totally summed up. On the basis of isochronal stratigraphic framework, with the outcop observation, core description,and log facies analysis, combing with rock ty -pe,depositional texture, structure characteristics, ect, types of sedimentary facies, development characteristics, and vertieal and horizontal distribution are analyzed. Eventually the research is used to analyse the types,and control factors of potential lithological and stratigraphical traps and to predict favorable exploration area at the key block, so it will improve the accuracy of reservoir prediction and provide foundation for integral deployment of petroleum exploration.The conclusions of this thesis can be summarized as follows:1. Five isochronous sequence boundaries are developed, the bottom-up is T48, T46a2, T46a1, T46h, T46, and four third-order sequences are divided from T-SQ1 to T-SQ4. By the the regional basin-wide seismic interpretation program, the basal boundary is changed from T50 to T48. So the boundary of Ketu’er formation of Triassic and Sajingzi formation of Permian is amended, which is hard to be distinguished by tailored lithologic character and color.2. By the the the regional basin-wide seismic interpretation program, although both Tazhong and Tabei area are used the 3 sub-programs, due to the thick mudstone in basal Triassic.and the similarity of the mudstone. The thick mudstone in basal T-SQ1 sequence in Tazhong area is formed the deposition during the TST to early HST. Whereas T-SQ1 sequence is widespread absent in Tahe area, The thick mudstone belongs to T-SQ2 sequence during the TST to early HST. Overall, the stratigraphic program between Tazhong and Tahe area is misplaced. Prior program was divided by rock formation, which results in the diachronous phenomenon.3. From the identification of sequence boundaries and analysis of typical inside structure, the "Three triple" structure include LST, TST and HST is beyond doubt.Due to the different positions of the basin margin as well as the conditions of very wide and gentle slope in the lake, small changes of lake level can cause the long-distance migration of shoreline, the lake range is rapidly declined during LST, resulting a small range, thin thickness and the lackage of low fan bodies and large-scale foreset reflection configuration. besides, LST is widespread absent in the slope of high position. The ultra-long-distance onlap is widely developed during TST. The typical feature of HST is that a wide range of gentle foreset reflection is well developed. This is quite different from the pattern of shelf- break background, which develops the low fan and a low wedge with high angle "S" type characteristics. The platform area is the uplift backward unit of foreland basin system, its evolution and sequence structure is controlled by extrusion process. The feature that settlement center within a single sequence and multiple sequence is migrated northward is the concrete manifestation. That is, sequence is controlled by the episodic and bending process.4. In the terms of sequence structure and sedimentary inside evolution, with an environment with gentle slope, shallow water and rich deposition, the braided river delta in the Triassic of platform area was deposited extensively in the shore- shallow lake background,which represent the deposition of broad-shallow depression lake basin. The corresponding 4 kinds of favorable reservoir sand is formed:braided channel, underwater distributary channel, channel mouth bar and distal bar. bathyal facies is only developed during the TST and early HST. Braided channel extends to the underwater with a long distance, the typical underwater channel is formed. And in the background of a small lake level change, the more fine-grained sedimentary bodies of channel mouth bar formed pre-stacked plot in delta sequence are not preserved completely by the erosion and cut-off of posterior underwater distributary channel. At last sand bodies of underwater distributary channel is gradually dominated and the important feather is they’re the key sandbodies. They show the constantly advanced to the abdomen of basin and mutually overlying complex delta bodies Finally, the third sequence is "retrogradation→progradation" evolutionary of the internal braided river delta→brink-shallow lake→braided river delta. And braided river delta is developed widespreadly in the LST, early TST and middle-late HST, the shallow lake and demi-deep lake thick mudstone is developed during late TST and early HST.5. In view of the ideas that Triassic reservoir sandbodies are extremely developed, reservoir performance is better, distribution is large, secondary hydrocarbon reservoir is the main reservoir and favorable traps are lithologic-stratigraphic and complex structural lithologic traps, the key term of reservoir is whether has valid conduction and blankoff- guarded element. Studies suggest that the following three slope positions have a good exploration prospects:south Tabei-Shunbei area, Manxi-Shunxi area and south Awati area.更多还原