Accumulation characteristics and the main controlling factors of Lunnan multilayer oil province,Tarim Basin,China

Lunnan region is a large-scale paleohigh with many coexisting oil and gas bearing series. At present, about 2 billions tons of proved, probable and possible oil and gas reverses have been proved there. Eight oil and gas bearing series have been found in the Ordovician, Carboniferous, Triassic and Jurassic of Lunnan region, they all bear the characteristics of large-scale multilayer oil-gas province. Ordovician is the main reservoir series where over 0.8 billion tons of oil geologic reserves were discovered, and a super large-scale marine carbonate oil and gas field has formed. Reservoir space of the carbonate reservoirs is mainly composed of dissolved hole, dissolved pore and fracture in Lunnan paleo-burial hill. Generally, dissolved holes are widely distributed among them. Reservoir developments are mainly controlled by karstification and tectonic disruption. Due to the similar geochemical characters, the Ordovician, Carboniferous, Triassic and Jurassic oil and gas reservoirs present the same oil source rock of Mid-Upper Ordovician, the latter except Ordovician are mostly of secondary oil and gas reservoirs migrated vertically by faults during the process of multiple phase tectonic movement, adjustment and reconstruction. Lunnan composite oil and gas accumulation region is situated in the vicinity of large-scale hydrocarbon generation depressions in three directions, ample oil and gas from hydrocarbon generation depressions supplied the adjacent oil and gas reservoirs once. Hereby, the succeed paleohigh is the long-term hydrocarbon accumulation region, which is favor for the formations of high quality reservors, fault systems and huge-scale composite oil and gas accumulation.     

Accumulation characteristics and the main controlling factors of Lunnan multilayer oil province,Tarim Basin,China

Lunnan region is a large-scale paleohigh with many coexisting oil and gas bearing series.At present, about 2 billions tons of proved,probable and possible oil and gas reverses have been proved there.Eight oil and gas bearing series have been found in the Ordovician,Carboniferous,Triassic and Jurassic of Lunnan region,they all bear the characteristics of large-scale multilayer oil-gas province.Ordovician is the main reservoir series where over 0.8 billion tons of oil geologic reserves were discovered,and a super large-scale marine carbonate oil and gas field has formed.Reservoir space of the carbonate reservoirs is mainly composed of dissolved hole,dissolved pore and fracture in Lunnan paleo-burial hill.Generally, dissolved holes are widely distributed among them.Reservoir developments are mainly controlled by karstification and tectonic disruption.Due to the similar geochemical characters,the Ordovician,Carboniferous,Triassic and Jurassic oil and gas reservoirs present the same oil source rock of Mid-Upper Ordovician,the latter except Ordovician are mostly of secondary oil and gas reservoirs migrated vertically by faults during the process of multiple phase tectonic movement,adjustment and reconstruction. Lunnan composite oil and gas accumulation region is situated in the vicinity of large-scale hydrocarbon generation depressions in three directions,ample oil and gas from hydrocarbon generation depressions supplied the adjacent oil and gas reservoirs once.Hereby,the succeed paleohigh is the long-term hydrocarbon accumulation region,which is favor for the formations of high quality reservoirs,fault systems and huge-scale composite oil and gas accumulation.     

Kinetics of hydrocarbon generation for Well Yingnan 2 gas reservoir,Tarim Basin,China

Well Yingnan 2, an important exploratory well in the east of Tarim Basin, yields high commercial oil and gas flow in Jurassic. Natural gas components and carbon isotopic composition indicate that it belongs to sapropel type gas. Because this region presents many suits of hydrocarbon source rocks, there are some controversies that natural gases were generated from kerogen gas or crude oil cracking gas at present. By using the kinetics of hydrocarbon generation and carbon isotope, natural gas of Well Yingnan 2 is composed mainly of crude oil cracking gas, about 72%, it is generated from secondary kerogen gas of Cambrian-Lower Ordovician source rock and crude oil cracking gas of Mid-Upper Ordovician oil reservoir. The main oil and gas filling time is 65 Ma later in the Jurassic gas reservoir of Well Yingnan 2, so the gas reservoir belongs to late accumulation and continuous filling type.

     

Kinetics of hydrocarbon generation for Well Yingnan 2 gas reservoir,Tarim Basin,China

Well Yingnan 2, an important exploratory well in the east of Tarim Basin, yields high commercial oil and gas flow in Jurassic. Natural gas components and carbon isotopic composition indicate that it belongs to sapropel type gas. Because this region presents many suits of hydrocarbon source rocks, there are some controversies that natural gases were generated from kerogen gas or crude oil cracking gas at present. By using the kinetics of hydrocarbon generation and carbon isotope, natural gas of Well Yingnan 2 is composed mainly of crude oil cracking gas, about 72%, it is generated from secondary kerogen gas of Cambrian-Lower Ordovician source rock and crude oil cracking gas of Mid-Upper Ordovician oil reservoir. The main oil and gas filling time is 65 Ma later in the Jurassic gas reservoir of Well Yingnan 2, so the gas reservoir belongs to late accumulation and continuous filling type.     

Kinetics of hydrocarbon generation for Well Yingnan 2 gas reservoir,Tarim Basin,CHina

Well Yingnan 2,an important exploratory well in the east of Tarim Basin,yields high commercial oil and gas flow in Jurassic.Natural gas components and carbon isotopic composition indicate that it belongs to sapropel type gas.Because this region presents many suits of hydrocarbon source rocks,there are some controversies that natural gases were generated from kerogen gas or crude oil cracking gas at present.By using the kinetics of hydrocarbon generation and carbon isotope,natural gas of Well Yingnan 2 is composed mainly of crude oil cracking gas,about 72%,it is generated from secondary kerogen gas of Cambrian-Lower Ordovician source rock and crude oil cracking gas of Mid-Upper Ordovician oil reservoir.The main oil and gas filling time is 65 Ma later in the Jurassic gas reservoir of Well Yingnan 2,so the gas reservoir belongs to late accumulation and continuous filling type.     

二连盆地“三明治”电性结构特征及其对古生界的研究意义

由于长期以来东北地区晚古生代的构造属性一直被认为是海西期褶皱带或碰撞造山带,而一直被作为中、新生代盆地的变质结晶基底成为油气勘查的禁区,限制了古生界的油气勘探和开发."佳木斯—兴蒙地块"新认识及二连盆地赛51井取得的石炭纪碳酸盐岩油藏的发现,开辟了二连盆地古生界油气勘探的新领域.本文对二连盆地3条典型的CEMP电测量资料进行了二维电阻率反演,结合研究区地震反射资料、钻孔电测井资料、钻井岩芯资料、岩石露头资料,揭示了二连盆地具有"三明治"的电性结构特征,同时指出二连盆地古生界广泛分布,在古生界与中生界之间广泛分布一套以玄武岩、安山岩、凝灰岩等为主的火山岩.这种"三明治"电性结构特征不但给古生界的研究提供了线索和依据,而且火山岩(高阻层)与其下伏古生界地层(低阻层)之间可形成良好的储盖组合(或生储盖组合),其对于古生界油气勘探的研究具有重要的意义.同时,认为二连盆地中、新生界和古生界的构造沉积演化主要经历了4个重要阶段,即:泥盆纪的南北差异性升降阶段、石炭-二叠纪的地层稳定沉积阶段、三叠纪-晚侏罗世的古生代盆地被改造和中新生代盆地构造格架形成的重要演化阶段以及中新生代的地层沉积阶段.     

Oil source analysis of Upper Tertiary Shawan Formation in Chepaizi area,in the northwest margin of Junggar basin

Well che89, located in the Chepaizi area in the northwest margin of Junggar basin, acquires high production industrial oil flow, which is an important breakthrough in the exploration of the south foreland slope area of Junggar basin. The Chepaizi area is near two hydrocarbon generation depressions of Sikeshu and Shawan, which have sets of hydrocarbon source rock of Carboniferous to Jurassic as well as Upper Tertiary. Geological and geochemical parameters are proper for the accumulation of mixed source crude oil. Carbon isotope, group composition and biomarkers of crude oil in Upper Tertiary of well Che89 show that the features of crude oil in Upper Tertiary Shawan Formation are between that of Permian and Jurassic, some of them are similar to these two, and some are of difference, they should be the mixed source of Permian and Jurassic. Geochemical analysis and geological study show that sand extract of Lower Tertiary Wulunguhe Formation has the same source as the crude oil and sand extract of Upper Tertiary Shawan Formation, but they are not charged in the same period. Oil/gas of Wulunguhe Formation is charged before Upper Tertiary sedimentation, and suffered serious biodegradation and oxidation and rinsing, which provide a proof in another aspect that the crude oil of Upper Tertiary Shawan Formation of well Che89 is not from hydrocarbon source rock of Lower Tertiary.     

Oil source analysis of Upper Tertiary Shawan Formation in Chepaizi area,in the northwest margin of Junggar basin

Well che89, located in the Chepaizi area in the northwest margin of Junggar basin, acquires high production industrial oil flow, which is an important breakthrough in the exploration of the south foreland slope area of Junggar basin. The Chepaizi area is near two hydrocarbon generation depressions of Sikeshu and Shawan, which have sets of hydrocarbon source rock of Carboniferous to Jurassic as well as Upper Tertiary. Geological and geochemical parameters are proper for the accumulation of mixed source crude oil. Carbon isotope, group composition and biomarkers of crude oil in Upper Tertiary of well Che89 show that the features of crude oil in Upper Tertiary Shawan Formation are between that of Permian and Jurassic, some of them are similar to these two, and some are of difference, they should be the mixed source of Permian and Jurassic. Geochemical analysis and geological study show that sand extract of Lower Tertiary Wulunguhe Formation has the same source as the crude oil and sand extract of Upper Tertiary Shawan Formation, but they are not charged in the same period. Oil/gas of Wulunguhe Formation is charged before Upper Tertiary sedimentation, and suffered serious biodegradation and oxidation and rinsing, which provide a proof in another aspect that the crude oil of Upper Tertiary Shawan Formation of well Che89 is not from hydrocarbon source rock of Lower Tertiary.

     

塔里木盆地地球动力学演化与含油气系统旋回

论述了塔里木盆地的地球动力学演化过程,指出震旦-三叠纪和侏罗-第四纪是两个构造巨旋回．在这类旋回中,盆地经历了由伸展到聚敛的完整发育过程塔里木盆地的演化总体上表现为强伸展-聚敛-微伸展-强聚敛的特点盆地动力学旋回决定了油气的生运聚散过程．提出含油气系统旋口的概念．在分析寒武-奥陶系含油气系统旋回、石炭系-下二叠统含油气系统旋回和侏罗系含油气系统旋回的基础上,指出对含油气系统旋回的形成期与调整再分配期的研究更具实际意义．     

Recent developments in study of the typical superimposed basins and petroleum accumulation in China:Exemplified by the Tarim Basin

Most of petroliferous sedimentary basins in China have experienced multiple phases of tectonic evolution and deposition, and are characterized by tectonic and depositional superimposition. The term "superimposed basin" is suggested to describe those basins which consist of two or more simple prototype basins superimposing vertically and/or coalescing laterally. The characteristics of petroliferous superimposed basins are "multiple stages of basin forming and reworking, multiple layers of source rocks, multiple periods of hydrocarbon generation and expulsion, multiple periods of petroleum migration-accumulation-escape". Therefore,applying the wave process analysis method to studying the process of basin formation, hydrocarbon generation, and reservoir formation, and then establishing theory of "petroleum accumulation system" is helpful to enhancing petroleum exploration efficiency in superimposed basins.This paper will, based on case study in the Tarim basin, report the major developments in studying basin formation, hydrocarbon generation and petroleum accumulation. In study of basin formation, (1) geophysical comprehensive profiles reveal that the Tarim plate has been subducted beneath the Tianshan orogenic belt with an interfinger structure and that the deep structure in the eastern section of the Tianshan orogenic belt is different from that in the western section. (2) The vertical variation in debris and geochemical composition reveals the nature and Mesozoic-Cenozoic evolution history of the Kuqa Depression. (3) Field investigation and paleostress reconstruction show that the Kuqa Depression has undergone gravity-driven extension in sedimentary cover when the Tianshan uplifted vertically. In hydrocarbon generation study, new developments include (1) setting environmental index to judge high grade source rocks in marine carbonates, and (2) establishing the lower limit of the organic carbon content for effective carbonate source rocks. In petroleum accumulation study, (1) methods of determining paleopressure and paleotemperature of forming fluid inclusions have been established. (2) The petroleum source analysis has indicated that the crude oil in the Lunnan and Tahe oilfields are derived from the source rocks of the Middle and Upper Ordovician. (3) Three generations of oil inclusions from the Lunnan oilfield have been recognized and dated.     

西藏羌塘盆地的深部构造与含油气远景评价

羌塘盆地是目前国内石油勘探的热点地区之一,作者综合研究了羌塘盆地的地球物理、石油地质调查资料及INDEPTH-3深部调查结果,得出:1, 盆地内烃源层、储集层、盖层及其组合条件很好, 局部构造发育,有利于形成和保存油气藏,断裂不会成为致命问题,提出了今后工作的主要目的层为上三叠世-中侏罗系组成的中构造层;2,对盆地二级构造作了新的划分,否定羌中隆起,提出盆地表层的主要构造方向为北西-南东向,成“三凹三隆”及“一深凹”的地壳结构特征,其中主沉降带内部及其两侧是最有利的找油气远景地带;3,本区壳幔之间的相互作用较强,盆地北部火山及热活动多,对油气远景评价有较大影响,而盆地南部沉积厚度大,受深层热影响相对较小,是找油气的更有利的地段。4,强调查明深部地层物性、油气赋存状况,烃类物质的来源和上下构造符合情况是当务之急。重点是加强点上的调查和评价研究;5,提出不能轻视伦坡拉陆相第三系盆地找油前景,它可能汇聚有两侧海相地层的油气。     

应用地震数据体结构特征法预测塔河油田八区油层分布规律

地震数据体结构特征,指对二维或三维地震数据体中每一地震道离散数据点按时间顺序排列所显示的波形特征。应用地震数据体结构特征法对储层进行油气预测,是近年来新兴的一项储层预测技术。塔河油田八区的主产层为碳酸盐岩裂缝一缝洞型储层,具有很强的非均质性,给储层的油气预测带来了一定的困难。针对塔河油田八区特殊的地质条件,采用了地震数据体结构特征法对该区奥陶系储层进行了油气预测,并对油区内、外的区域进行了有利区块的划分。在有利区块中设计的18口钻探井位,经钻井证实均获得了较高的油气产量,取得了很好的经济效益。     

Predicting the distribution of reservoirs by applying the method of seismic data structure characteristics： Example from the eighth zone in Tahe Oilfield

Seismic data structure characteristics means the waveform character arranged in the time sequence at discrete data points in each 2-D or 3-D seismic trace. Hydrocarbon prediction using seismic data structure characteristics is a new reservoir prediction technique. When the main pay interval is in carbonate fracture and fissure-cavern type reservoirs with very strong inhomogeneity, there are some difficulties with hydrocarbon prediction. Because of the special geological conditions of the eighth zone in the Tahe oil field, we apply seismic data structure characteristics to hydrocarbon prediction for the Ordovician reservoir in this zone. We divide the area oil zone into favorable and unfavorable blocks. Eighteen well locations were proposed in the favorable oil block, drilled, and recovered higher output of oil and gas.     

Characteristics,genesis and accumulation history of natural gas in Hetianhe gasfield,Tarim Basin,China

Hetianhe gasfield in Bachu region of the Tarim Basin is mainly composed of three reservoir-caprock assembly, namely regional caprock of upper mudstone, middle mudstone and lower mudstone of the Carboniferous and reservoir of Bachu bioclastic limestone, glutenite and the Ordovician carbonate buried hill. Natural gas in Hetianhe gasfield sourced from the Cambrian source rock. It is thought that gases in Ma4 well block in the east of Hetianhe gasfield are mainly crude-oil cracked gases, while those in Ma3 and Ma8 well blocks in the west are the mixture gases of kerogen cracked gases and crude-oil cracked gases. Natural gas is rich in H₂S and accumulated in multiply stages as the result of TSR. The accumulation history is divided into three stages, namely accumulation and breakage in the late Caledonian-early Hercynian, migration and dissipation in the late Hercynian and accumulation in Himalayan. The main accumulation of reformed gas reservoir is in Himalayan.

     

Characteristics,genesis and accumulation history of natural gas in Hetianhe gasfield,Tarim Basin,China

Hetianhe gasfield in Bachu region of the Tarim Basin is mainly composed of three reservoir-caprock assembly, namely regional caprock of upper mudstone, middle mudstone and lower mudstone of the Carboniferous and reservoir of Bachu bioclastic limestone, glutenite and the Ordovician carbonate buried hill. Natural gas in Hetianhe gasfield sourced from the Cambrian source rock. It is thought that gases in Ma4 well block in the east of Hetianhe gasfield are mainly crude-oil cracked gases, while those in Ma3 and Ma8 well blocks in the west are the mixture gases of kerogen cracked gases and crude-oil cracked gases. Natural gas is rich in H₂S and accumulated in multiply stages as the result of TSR. The accumulation history is divided into three stages, namely accumulation and breakage in the late Caledonian-early Hercynian, migration and dissipation in the late Hercynian and accumulation in Himalayan. The main accumulation of reformed gas reservoir is in Himalayan.     

Characteristics,genesis and accumulation history of natural gas in Hetianhe gasfield,Tarim Basin,China

Hetianhe gasfield in Bachu region of the Tarim Basin is mainly composed of three reservoir-caprock assembly,namely regional caprock of upper mudstone,middle mudstone and lower mudstone of the Carboniferous and reservoir of Bachu bioclastic limestone,glutenite and the Ordovician carbonate buried hill.Natural gas in Hetianhe gasfield sourced from the Cambrian source rock.It is thought that gases in Ma4 well block in the east of Hetianhe gasfield are mainly crude-oil cracked gases,while those in Ma3 and Ma8 well blocks in the west are the mixture gases of kerogen cracked gases and crude-oil cracked gases.Natural gas is rich in H2S and accumulated in multiply stages as the result of TSR.The accumulation history is divided into three stages,namely accumulation and breakage in the late Caledonian-early Hercynian,migration and dissipation in the late Hercynian and accumulation in Himalayan. The main accumulation of reformed gas reservoir is in Himalayan.     

南海南北大陆边缘盆地构造演化差异性对油气成藏条件控制

南海大陆边缘盆地由于边界条件的差异,形成了离散型、走滑-伸展型和伸展-挠曲复合型3类陆缘盆地.这些盆地由于其构造演化差异性,导致了盆地沉积充填存在较大差异,相应地导致这些盆地油气成藏条件及油气资源量的巨大差异.南海北部离散型大陆边缘盆地主要发育湖相泥岩和海相泥岩烃源岩,尽管存在较好的湖相烃源岩,但由于各断陷分隔且面积较...     

Potential petroleum sources and exploration directions around the Manjar Sag in the Tarim Basin

Since the discovery of the Tahe oilfield, it has been controversial on whether the main source rock is in the Cambrian or Middle-Upper Ordovician strata. In this paper, it is assumed that the crude oil from the Wells YM 2 and TD 2 was derived from the Middle-Upper Ordovician and Cambrian source rocks, respectively. We analyzed the biomarkers of the crude oil, asphalt-adsorbed hydrocarbon and saturated hydrocarbon in bitumen inclusions from the Lunnan and Hade areas in the North Uplift of the Tarim Basin. Results show that the ratios of tricyclic terpane C₂₁/C₂₃ in the crude oil, asphalt-adsorbed hydrocarbon and saturated hydrocarbon in bitumen inclusions are less than 1.0, indicating that they might be from Upper Ordovician source rocks; the ratios of C₂₈/(C₂₇+C₂₈+C₂₉) steranes in the saturated hydrocarbon from reservoir bitumen and bitumen inclusions are higher than 25, suggesting that they might come from the Cambrian source rocks, however, the ratios of C₂₈/(C₂₇+C₂₈+C₂₉) steranes in oil from the North Uplift are less than 25, suggesting that they might be sourced from the Upper Ordovician source rocks. These findings demonstrate that the sources of crude oil in the Tarim Basin are complicated. The chemical composition and carbon isotopes of Ordovician reservoired oil in the Tarim Basin indicated that the crude oil in the North Uplift (including the Tahe oilfield) and Tazhong Depression was within mixture areas of crude oil from the Wells YM 2 and TD 2 as the end members of the Cambrian and Middle-Upper Ordovician sourced oils, respectively. This observation suggests that the crude oil in the Ordovician strata is a mixture of oils from the Cambrian and Ordovician source rocks, with increasing contribution from the Cambrian source rocks from the southern slope of the North Uplift to northern slope of the Central Uplift of the Tarim Basin. Considering the lithology and sedimentary facies data, the spatial distribution of the Cambrian, Middle-Lower Ordovician and Upper Ordovician source rocks was reconstructed on the basis of seismic reflection characteristics, and high-quality source rocks were revealed to be mainly located in the slope belt of the basin and were longitudinally developed over the maximum flooding surface during the progressive-regressive cycle. Affected by the transformation of the tectonic framework in the basin, the overlays of source rocks in different regions are different and the distribution of oil and gas was determined by the initial basin sedimentary structure and later reformation process. The northern slope of the Central Uplift-Shuntuo-Gucheng areas would be a recent important target for oil and gas exploration, since they have been near the slope area for a long time.     

Jurassic sedimentary features and tectonic settings of southeastern China

Two types of the Jurassic basins are distinguished in SE China based on their geodynamic features: the Late Triassic-Early Jurassic post-orogenic basins and the Middle Jurassic intra-continental extensional basins. The Lower Jurassic sequence shows a change from coarse- to fine-grained accumulation, suggesting a gradually deepening depositional environment from river to shore-lake and to deep-water lake. In contrast, the Middle Jurassic accumulation was changed from claystone to conglomerate along the coastal provinces in SE China, indicative of an initial crustal uplift. The Wuyi Mountains have been a paleogeograghic separating zone since the Middle Jurassic. The Late Jurassic strata are absent in most areas of SE China. A large-scale bimodal intra-continental rift-type volcanism occurred during the Middle Jurassic along a 40–60 km wide and 200 km long area in western Fujian and southern Jiangxi provinces, which is most likely the strongest volcanism in SE China since the Cambrian. The SHRIMP zircon U-Pb analyses on the rhyolite from the Dongkeng basin in the southern Jiangxi area yield a concord U-Pb age of 160±0.5 Ma, providing an upper age limit for the bimodal volcanic eruption. The analyses of the basin features indicate a change of the depositional environment during the interval from Middle Triassic to Late Triassic from a shallow-sea to an intra-continent in SE China in response to the strong collision between the Yangtze and North China Blocks. Sedimentary structures record a southward direction of Early Jurassic paleo-currents, reflecting that their source areas were to the north side. We propose that the Wuyi region was uplifted as early as Middle Jurassic, followed by a wide E-W-trending extended depression and bimodal volcanism in the western foot of the Wuyi Mountains. Presumably the uplift of the Wuyi domain changed the Middle Jurassic paleogeographic outline and formed the transformational tectonic regime from compression to extension as a tectonic response to the Pacific plate subduction.     

塔里木盆地轮南奥陶系风化壳SYT法物性探测试验研究

ＳＹＴ型物性探测仪自从１９９２年石油系统使用之后,先后在陕北,华北,吉林,大庆油田取得了一定的试验效果,在仪器硬件和方法软件不断改进的基础上,在塔里木盆地轮南地区又进行了深为５７００余米的探测试验,其界面探测精度误差为０．５％～１．２％,在地面上直接解译奥灰顶界面深度,奥灰风化壳裂隙性岩溶发育程度,判译地下油气有等方面,无疑这将会大大降低对油气勘探投资的风险系数,塔里木盆地轮南奥灰风化壳ＳＹＴ法试