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柴西北上干柴沟组咸化湖盆天文旋回识别及沉积速率分析
吴颜雄, 徐帆, 王波, 裴梓薇, 施奇, 朱超, 宫清顺, 刘占国, 夏志远, 田明智, 李娴静
海相油气地质 ›› 2026, Vol. 31 ›› Issue (2) : 164-174.
PDF(8012 KB)
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柴西北上干柴沟组咸化湖盆天文旋回识别及沉积速率分析
Identification of astronomical cycles and analysis of sedimentation rates in the salinized lake basin of the Shangganchaigou Formation in the northwestern Qaidam Basin
柴达木盆地西北部（柴西北）上干柴沟组（N1）主要发育咸化湖盆细粒混积岩，是非常规油气勘探的重要领域，但目前在旋回地层学和高精度天文旋回沉积响应特征方面的研究较为薄弱。综合利用岩心和测井数据，开展了2口钻井的旋回地层学分析，在上干柴沟组识别出长偏心率、短偏心率、斜率和岁差等米兰科维奇旋回，并依据405 ka的长偏心率周期建立了浮动天文年代标尺，明确了上干柴沟组的沉积速率和沉积特征。研究表明：①上干柴沟组的沉积时间约4 Ma，平均沉积速率可达20 cm/ka，明显高于国内其他陆相湖盆地层；②上干柴沟组的岩相受沉积速率控制明显，高速率段主要发育富有机质的纹层状灰质白云岩，低速率段主要为贫有机质的块状含白云石泥质-粉砂质灰岩。③喜马拉雅期持续造山的构造活动在宏观尺度控制了上干柴沟组的高沉积速率，短期气候交替塑造了沉积速率的振荡变化。对柴西北上干柴沟组天文旋回的识别和沉积速率的分析，有助于理解咸化湖盆有利勘探层段的沉积演化，可为后续的页岩油高效勘探开发提供新的思路。
The Shangganchaigou Formation (N1) in the northwestern Qaidam Basin mainly consists of fine-grained mixed rocks deposited in a saline lake basin, representing an important field for unconventional oil and gas exploration. However, current research on cyclostratigraphy and high-precision astronomical sedimentary response characteristics in this formation remains relatively weak. By comprehensively integrating core and well-logging data, cyclostratigraphic analysis is performed on two drilling wells, identifying Milankovitch cycles including long eccentricity, short eccentricity, obliquity, and precession in the Shangganchaigou Formation, and a floating astronomical time scale is established based on the 405 ka long eccentricity cycle, thereby determining the sedimentation rate and sedimentary characteristics of the Shangganchaigou Formation. It is shown that: (1) Sedimentation time of N1 is approximately 4 Ma, and the average sedimentation rate can reach 20 cm/ka, which is significantly higher than that of other continental lacustrine strata in China. (2) The lithofacies characteristics based on sedimentation rate analysis indicate that lithofacies are significantly controlled by the sedimentation rate. Laminated dolomitic limestone with high organic matter content mainly develops in high-rate segments, while massive argillaceous-silty dolomitic limestone with low organic matter content is dominant in low-rate segments. (3) The continuous orogenic tectonic activity during the Himalayan period control the high sedimentation rate of N1 at a macroscopic scale, and short-term climate alternations shape the oscillatory changes in the sedimentation rate. The identification of astronomical cycles and analysis of sedimentation rates of N1 in the the northwestern Qaidam Basin are helpful for understanding the sedimentary evolution of favorable exploration intervals in salinized lake basins and can provide new ideas for the subsequent efficient exploration and development of shale oil.
天文旋回 / 沉积速率 / 岩相 / 上干柴沟组 / 柴西北
astronomical cycle / sedimentation rate / lithofacies / Shangganchaigou Formation / northwestern Qaidam Basin
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根据自然伽马测井数据，对吐哈盆地胜北洼陷沁探1井中下侏罗统水西沟群开展旋回地层学分析和沉积噪声模拟，并利用识别出的地层中的米兰科维奇旋回信号来研究地球轨道周期对湖平面变化的驱动作用，进而进行天文旋回地层划分。研究结果表明：①吐哈盆地胜北洼陷中下侏罗统水西沟群在自然伽马曲线中可识别出12.8～51.1 m，3.0～11.9 m，1.1～3.6 m和1.3～2.4 m的沉积旋回，比例关系为21.0∶5.0∶1.5∶1.0。根据天文调谐与相关系数估算出水西沟群沉积速率为3.3～11.7 cm·ka<sup>-1</sup>。②天文调谐后的时间域序列显示水西沟群长偏心率周期为405 ka、短偏心率周期为99～131 ka、斜率周期为32.6～35.0 ka、岁差周期为20.0～24.8 ka，证明吐哈盆地中下侏罗统沉积过程受到米兰科维奇旋回控制。沁探1井八道湾组（未钻穿）、三工河组和西山窑组的持续时间分别为3.0±0.1 Ma，4.1±0.1 Ma和9.0±0.1 Ma。③地球轨道旋回对陆相湖盆的湖平面升降具有明显的驱动作用，沁探1井水西沟群的沉积噪声模拟证明了～1.5 Ma超长周期可控制台北凹陷早—中侏罗世湖平面的变化。
The natural gamma-ray（<i>GR</i>）logging data of the early-middle Jurassic Shuixigou Group from QinTan 1 borehole in Shengbei subsag，Tuha basin，was selected to analyze cyclostratigraphy and simulate sedimentary noise for the identification of stratigraphic Milankovitch signals and determination of the Earth’s orbital cycle’s forcing the lake level variations within the Tuha Basin. The stratigraphic division of Shuixigou Group was ana lyzed. The results show that：（1）The sedimentary cycles of 12.8～51.1 m，3～11.9 m，1.1～3.6 m，and 1.3～ 2.4 m were identified in the <i>GR</i> curves of the Early-Middle Jurassic Shuixigou Group in the Shengbei subsag of Tuha Basin，with a ratio of 21∶5∶1.5∶1，and the sedimentary rates of the Shuixigou Group are estimated as 3.6～ 11.7 cm·ka<sup>-1</sup> through astronomical calibration and correlation coefficient.（2）The sedimentary records of the Shuixigou Group were forced by the Milankovitch cycles，as evidenced by the presence of 405 ka long eccentricity， 99～131 ka short eccentricity，32.6～35.0 ka obliquity，and 20.0～24.8 ka precession cycles during the Middle and Early Jurassic in Tuha basin. The durations of Badaowan Formation（not drilled through），Sangonghe Formation and Xishanyao Formation in Qintan 1 borehole are 3.0 ±0.1 Ma，4.1 ±0.1 Ma and 9.0 ±0.1 Ma， respectively.（3）The fluctuation of lake level forced by the Earth’s orbital cycles of terrestrial lake basins，the simulation of lake level change by sedimentary noise confirms that the ultra-long period of ～1.5 Ma forced the lake level change of the Shuixigou Group in Taibei sag.
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Based on the analysis of petroleum geological conditions of Qaidam Basin, four patterns of oil accumulation in paleouplift around hydrocarbon-rich sag, in paleouplift-paleoslope outside source rocks, in late structure above source rocks and in tight reservoir or lithologic traps are setup. The analogy method and genesis method are used to objectively evaluate the oil resource of different zones, blocks and strata. The results show that the amounts of the conventional oil and tight oil resource are 29.59×108 t and 8.58×108 t respectively. Combining with the current situation of petroleum exploration in the basin, the remaining conventional oil resources and their distribution are clarified. The areas with the most abundant remaining oil resources are located in the western Qaidam Basin. It is pointed out that paleo-uplift of basin margin and slope area, sag-slope zone in basin and large-scale late structural zone in basin are the key exploration fields in the near future. It is also suggested that Shizigou-Dawusi structural zone, Youquanzi-Katmerik structural zone and western segment in front of Altun Mountain are favorable targets for conventional oil exploration, and Yuedong-Zahaquan-Wunan zone, Hongliuquan-Yuejin zone in southwestern Qaidam Basin and Xiaoliangshan-Nanyishan in northwestern Qaidam Basin are favorable targets for tight oil exploration.
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The Paleogene upper Xiaganchaigou Formation (E-3(2)) is the most important source rock and reservoir in the Qaidam Basin. However, there are few studies on the processes of hydrocarbon accumulation in this formation; therefore, its hydrocarbon resource potential has not been estimated reasonably. This paper evaluates the hydrocarbon generation properties in light of an improved hydrocarbon generation and expulsion potential model. According to the geochemical characteristics of source rocks and the petrological features of reservoirs, the potentials of different resource types, including conventional oil, tight oil and shale oil, are quantified by combining the buoyancy-driven hydrocarbon accumulation depth (BHAD) and the lower limit for movable resource abundance. The results show that the source rocks are characterized by a large thickness (more than 1000 m), moderate organic matter content, high marginal maturity and a high conversion rate (50% hydrocarbons have been discharged before R-o = 1%), which provide sufficient oil sources for reservoir formation. Moreover, the reservoirs in the Qaidam Basin consist mainly of low-porosity and low-permeability tight carbonates (porosity of 4.7% and permeability less than 1 mD). The maximum hydrocarbon generation, expulsion, retention and movable retention intensities at present are 350 x 10(4) t/km(2), 250 x 10(4) t/km(2), 130 x 10(4) t/km(2) and 125 x 10(4) t/km(2), respectively. The thresholds of hydrocarbon generation, expulsion and BHAD were 0.46% R-o, 0.67% R-o and 0.7% R-o, respectively. Moreover, the dynamic evolution process of hydrocarbon accumulation was divided into three evolution stages, namely, (a) initial hydrocarbon accumulation, (b) conventional hydrocarbon reservoir and shale oil accumulation and (c) unconventional tight oil accumulation. The conventional oil, tight oil and movable shale oil resource potentials were 10.44 x 10(8) t, 51.9 x 10(8) t and 390 x 10(8) t, respectively. This study demonstrates the good resource prospects of E-3(2) in the Qaidam Basin. A comprehensive workflow for unconventional petroleum resource potential evaluation is provided, and it has certain reference significance for other petroliferous basins, especially those in the early unconventional hydrocarbon exploration stage.
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松辽盆地北部青山口组页岩油的勘探开发潜力巨大,但目前对其沉积旋回格架及有机质富集响应模式认识不清。对古页1井青山口组的自然伽马测井数据分段开展小波变换分析和频谱分析,并综合岩心、测井资料和地球化学元素分析成果,识别出蕴含在该套沉积地层中的米兰科维奇旋回,建立了理论轨道周期与单井沉积旋回的联系,实现了松辽盆地青山口组高精度沉积旋回的识别与划分。依据400 ka的长偏心率周期建立了青山口组的"浮动"天文年代标尺,计算出青山口组的沉积时间在5.6 Ma,青山口组一段富有机质泥页岩为晚白垩世Cenomanian晚期—Turonian早期的产物。青山口组的米兰科维奇旋回可划分为14个长偏心率旋回和46个短偏心率旋回,长、短偏心率旋回分别对应层序地层学的四级、五级层序,由此可搭建研究区天文旋回层序地层格架,为深、浅水区的统一地层划分提供思路。基于建立的受控于长偏心率旋回的有机质沉积响应模式发现,偏心率接近极大值时对应沉积旋回为富有机质层段,该层段是页岩油勘探的潜在优质层段。
There is great exploration and development potential of shale oil in Qingshankou Formation in the north of Songliao Basin, but its sedimentary cycle framework and organic matter enrichment response model are still unclear. Based on wavelet transform analysis and spectral analysis of the natural gamma logging data of Qingshankou Formation in Well Guye1, in combination with analysis results of the core, logging data and geochemical elements, the paper identifies the Milankovich cycle in the sedimentary strata, establishes the relationship between the theoretical orbital period and the single-well sedimentary cycle, and achieves the identification and division of the high-precision sedimentary cycles of Qingshankou Formation in Songliao Basin. The floating astronomical timescale of Qingshankou Formation is established according to the long eccentricity period of 400 ka. The sedimentary time of Qingshankou Formation is calculated to be 5.6 Ma. The organic-rich mud shale of Member 1 of Qingshankou Formation deposits during Late Cenomanian to Early Turonian of the Late Cretaceous. The Milankovitch cycle of Qingshankou Formation can be divided into 14 long eccentricity cycles and 46 short eccentricity cycles. The long and short eccentricity cycles correspond to the fourth and fifth levels of sequence stratigraphy respectively. On this basis, the sequence stratigraphic framework of astronomical cycles can be built in the study area, thus providing an idea for the unified stratigraphic division of deep and shallow water areas. Based on the established sedimentary model controlled by the long eccentricity cycle, it is found that when the eccentricity is close to the maximum, the corresponding sedimentary cycle will be in the organic-rich interval, which is the potential high-quality interval for shale oil exploration.
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查宇铭, 吴欣松, 余达. 松辽盆地松科1井上白垩统烃源岩有机碳含量与沉积速率的关系[J]. 古地理学报, 2016, 18(5): 857-864.
与海相盆地相比,陆相湖盆沉积物TOC和沉积速率关系的研究尚处于探索阶段,尤其是在沉积作用对TOC的控制机理研究方面还有待深入。首先运用旋回地层学方法,识别了松科1井南孔上白垩统天文周期,并利用滑动窗口频谱分析方法计算了各窗口的沉积速率及对应的TOC值。以姥鲛烷和植烷(Pr/Ph)比值作为氧化还原条件的指标,以介形虫壳体的δ<sup>13</sup>C作为古生产力大小的指标,对不同环境和不同古生产力条件下TOC和沉积速率的关系进行了探讨。研究表明: 在还原环境下,TOC主要取决于古生产力高低,而沉积速率的影响相对较小,当古生产力较高时,TOC值一般大于1%;反之,TOC值小于1%。但在氧化环境、低古生产力条件下,TOC随着沉积速率先增大后减小,其临界值为11,cm/ka。
Compared with study in marine basins,study on the relationship between total organic carbon (TOC) content and sedimentation rate(SR)in continental lacustrine sediments is still in exploration phase,and the controlling mechanism of sedimentation on TOC especially needs intensive study. In this paper,astronomical cycles of the Upper Cretaceous in the southern borehole of Well CCSD-SK-1 were firstly identified with the cycle stratigraphy method; and then SR and the corresponding TOC of each window was calculated by moving-window spectral analysis method. Taking the Pr/Ph ratio as a redox condition index and <em>δ</em><sup>13</sup>C of the ostracod shell as a paleo-productivity index,the relationship of SR and TOC in different environments and different paleo-productivity conditions in detail was discussed. Analyses show that TOC is mainly controlled by palaeo-productivity while the influence of SR is very little; in a high palaeo-productivity environment the TOC value is larger than 1% and less than 1% in contrast. But under the oxidation and low palaeo-productivity conditions,the TOC value tends to increase with SR when SR is less than 11,cm/ka and then decreases in a higher SR background.
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珠江口盆地珠一坳陷发育3套烃源岩层系,自下而上有始新统文昌组、始新统—渐新统恩平组和渐新统珠海组。基于3套烃源岩层系的GR曲线资料，运用旋回地层分析方法(频谱分析技术及小波分析技术)实现了对珠一坳陷3套烃源岩层系天文周期的识别，并通过滤波技术精细计算了烃源岩沉积速率，得到2点基本认识：①珠一坳陷始新世—渐新世受天文周期影响，对应于天文周期(100ka偏心率周期、40ka斜率周期、20ka岁差周期)，文昌组存在厚度为19.8m、9.1m、3.8m 3种米兰科维奇旋回，恩平组存在厚度为17.0m、6.8m、3.4m 3种米兰科维奇旋回，珠海组存在厚度为9.2m、4.1m、1.8m 3种米兰科维奇旋回，其中偏心率周期的影响最为显著；②珠一坳陷3套烃源岩的沉积速率各自分布在一定的区间，不同沉积环境中烃源岩的沉积速率分布范围不同。文昌组中深湖相很好烃源岩沉积速率为8.50~14.00cm/ka，恩平组湖沼相好烃源岩沉积速率分布在8.00~15.50cm/ka之间，珠海组滨海相好烃源岩沉积速率分布在7.50~12.50cm/ka之间。
<div style="line-height: 150%">There are three series of source rocks in the Zhuyi Depression,Pearl River Mouth Basin,including Wenchang Formation (Eocene),Enping Formation (Eocene-Oligocene)and Zhuhai Formation (Oligocene).On the basis of GR curve,the astronomical orbital periods hidden in the source rock series are recognized by spectral analysis and wavelet analysis in the Zhuyi Depression.Meanwhile,the sedimentation rates of the source rocks have been calculated by utilizing band-pass filtering.Two conclusions have been obtained: (1)Sedimentation process in the Zhuyi Depression was influenced by the astronomical orbital periods from Eocene to Oligocene.Corresponding to the astronomical orbital periods (100ka Eccentricity,40ka Obliquity,20ka Precession),there are Milankovitch Cycles of 19.8m,9.1m and 3.8m in Wenchang Formation,17.0m,6.8m and 3.4m in Enping Formation,and 9.2m,4.1m and 1.8m in Zhuhai Formation respectively.Overall,Eccentricity had the most significant impact on these three formations.(2)Sedimentation rates of source rocks are in different ranges in different sedimentary environment.The sedimentation rates of Wenchang Formation′s excellent source rocks of middle-deep lacustrine facies lie between 8.50cm/ka and 14.00cm/ka.The sedimentation rates of Enping Formation′s good source rocks of limnetic facies lie between 8.00cm/ka and 15.50cm/ka.The sedimentation rates of Zhuhai Formation′s good source rocks of neritic facies lie between 7.50cm/ka and 12.50cm/ka.</div><div style="line-height: 150%"> </div><div style="line-height: 150%"> </div>
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张若琳, 金思丁. 渤海湾盆地沾化凹陷罗69井沙三下亚段旋回地层学研究[J]. 中南大学学报(自然科学版), 2021, 52(5): 1516-1531.
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Two end member models of how the high elevations in Tibet formed are (i) continuous thickening and widespread viscous flow of the crust and mantle of the entire plateau and (ii) time-dependent, localized shear between coherent lithospheric blocks. Recent studies of Cenozoic deformation, magmatism, and seismic structure lend support to the latter. Since India collided with Asia approximately 55 million years ago, the rise of the high Tibetan plateau likely occurred in three main steps, by successive growth and uplift of 300- to 500-kilometer-wide crustal thrust-wedges. The crust thickened, while the mantle, decoupled beneath gently dipping shear zones, did not. Sediment infilling, bathtub-like, of dammed intermontane basins formed flat high plains at each step. The existence of magmatic belts younging northward implies that slabs of Asian mantle subducted one after another under ranges north of the Himalayas. Subduction was oblique and accompanied by extrusion along the left lateral strike-slip faults that slice Tibet's east side. These mechanisms, akin to plate tectonics hidden by thickening crust, with slip-partitioning, account for the dominant growth of the Tibet Plateau toward the east and northeast.
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方小敏, 宋春晖, 戴霜, 等. 青藏高原东北部阶段性变形隆升: 西宁、贵德盆地高精度磁性地层和盆地演化记录[J]. 地学前缘, 2007, 14(1): 230-242.
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Clay mineralogy and its palaeoclimatic interpretation of the early-Eocene (∼53.3–49.70 Ma) sediments at Lulehe, Qaidam basin, northwest China, were investigated using optical microscopy, scanning electron microscopy (SEM), and X-ray diffraction (XRD). The interval of ∼53.3–49.70 Ma, including the early-Eocene climate optimum (EECO) with isotopic events, was the transition period of “greenhouse” to “icehouse”. Climate changes during the episode were documented in the sediments and were expressed by the proportion of clay species and clay indices, as well as by the proportion of non-clay minerals, gypsum, halite and calcite. Our results suggest that a warm and humid climate prevailed over the period ∼53.3–52.90 Ma, followed by a warm and seasonally dry and humid climate in the period ∼52.90–51.0 Ma and a subsequently warm and humid climate in the period ∼51.0–49.70 Ma. Three warmer and more humid intervals were observed at 52.7, 51.0 and 50.5 Ma based on clay indices. The climate evolution in the Qaidam Basin during the period derived from the clay mineralogical study is in good agreement with the early Eocene global climate change, and the warm and seasonally dry and humid episode in the early Eocene in Qaidam basin is a regional response to the global early-Eocene climate optimum.
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| [43] |
Clay mineralogy and bulk mineral composition of Tertiary sediments in Qaidam were investigated using X-ray diffraction (XRD) and scanning electron microscopy in order to better understand regional climate change resulting from uplift of the Northeast Tibetan Plateau. Climate change in Qaidam since ∼53.5 Ma could be divided into four stages: a warm and seasonally arid climate between ∼53.5 and 40 Ma, a cold and arid climate from ∼40 to 26 Ma, a warm and humid climate between ∼26 and 13.5 Ma, and a much colder and arid climate from ∼13.5 to 2.5 Ma, respectively. The illite crystallinity and sedimentary facies suggested that uplift events took place around >52–50, ∼40-38, ∼26-15, ∼10-8, and <5 Ma in the Qaidam region, respectively. The climate in Qaidam Basin could have been controlled by global climate prior to 13.5 Ma. As the Tibetan Plateau reached a significant elevation by ∼13.5 Ma, and the climate cycles of the East Asian monsoon might add additional influence. |
| [44] |
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| [45] |
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