【作者】 徐伟；

【导师】 解习农；

【作者基本信息】 中国地质大学 ， 矿产普查与勘探， 2011， 硕士

【摘要】 作为中国东部具有典型意义的油气聚集区,东营凹陷在近数十年的勘探中仍不断有新的发现,显示出巨大的油气资源潜力。与此同时,随着勘探程度的加深和勘探难度的加大,隐蔽油气藏(岩性油气藏为主)逐渐转变为主要的勘探对象,而东营凹陷沙河街组三段、四段则是岩性油气藏发育的重要层段。另一方面,一系列针对隐蔽油气藏勘探的理论和技术方法得到了空前发展,并在勘探实践中获得了极大成功。但是陆相断陷盆地构造活动强烈,岩性油气藏形成机制与分布规律复杂,地层旋回记录保存不完整,更为精细的地层划分受到诸多限制。高频旋回的研究为解决这一问题提供了新的思路,东营凹陷完备的地震、岩心、测井、测试数据则为高频旋回的研究提供了强有力的资料保障,而前人较高程度的研究也为本次研究打下了坚实的基础。陆相盆地受困于控制因素的复杂性和连续剖面的缺乏性,高频旋回的研究程度明显滞后于海相盆地。东营凹陷沙四段至沙三段经历了显著的气候变化,其中必然保留了相应的米兰科维奇旋回信息,本文选择气候变化最为明显,油气藏最为发育的沙四上至沙三中地层作为目的层段,以与气候变化紧密相关的自然伽马数据作为研究对象,对数据进行环境校正和标准化处理后,运用层序地层学、沉积学和米兰科维奇旋回地层学理论和方法,对其进行了系统的高频旋回研究,取得以下主要认识和结论：1.综合利用岩心、地震、测井、录井等数据,在沙四上至沙三中识别出了T4、T6、xT6、xT7四个三级层序界面,建立了相应的层序地层格架和等时地层格架,揭示了各层序沉积体系剖面和平面上的特征,分析了气候干湿变化对沉积特征的影响。2.采用La(2004)解决方案计算了东营凹陷30-50Ma地球轨道参数理论变化数据,运用频谱分析、连续小波变换对其进行分析发现,30-40Ma期间偏心率主要周期为405ka、124ka、95ka等,斜率周期主要为52ka、40ka、39ka、40-50Ma期间偏心率主要周期为405ka、125ka、96ka等,斜率周期主要为51ka、40ka、38ka,而岁差周期则均为23ka、22ka、19ka。进而提取出各主要周期的理论变化曲线,并计算了30-40Ma和40-50Ma期间各周期之间的比例关系。3.对所选科学探井的自然伽马曲线环境校正和标准化处理之后,运用频谱分析、连续小波变换等技术手段从沙四上至沙三中地层中识别出了米兰科维奇旋回,其中沙四上地层主要受40ka斜率周期控制,沙三下地层主要受405ka偏心率长周期控制,沙三中地层主要受125ka偏心率短周期控制。4.对从沙四上至沙三中地层中识别出的高频旋回轨道调谐后,选择控制各层段发育的主要米兰科维奇周期曲线,其中沙四上为40ka周期,34.5个斜率旋回,沙三下为405ka周期,4.5个长偏心率旋回,沙三中为125ka周期,短偏心率旋回个数大约为40,建立了各段地层的高分辨率天文年代标尺,较为精确的确定了各界面及不同深度对应的地质年龄。5.在区域地层格架的基础上,根据地震、岩心、测井等资料将沙三中东营三角洲精细划分为9期进积体Z1-Z9。对各期进积体进行滑动窗口频谱分析,结果表明沙三中沉积速率随时间先增大后减小,进积体Z4沉积速率达到最大值0.127m/ka,是三角洲进积最为鼎盛的时期。最后依据沉积速率计算出各期进积体持续时间,推算出了Z1-Z9各界面较为准确的地质年龄。选择窗口100m,步长50m,运用滑动窗口频谱分析计算了沙四上、沙三下地层的平均沉积速率,分别为0.11m/ka、0.19m/ka、并计算出各窗口持续时间。6.以沙三中底部界面上下各50m层段为例,利用计算出的沉积速率将自然伽马数据由深度域转换为时间域,获得新的时间序列,分别对其进行频谱分析和小波分析识别亚米兰科维奇旋回,沙三中底部向上50m层段存在12.06ka、11.29ka、7.94ka和6.6ka的周期,而沙三中底部向下50m层段存在11.7ka、8.35ka、6.5ka和5.85ka的亚米兰科维奇周期。7.以贯穿整个东营凹陷的东西向和南北向剖面10口钻井自然伽马数据为研究对象,分别进行频谱分析和小波分析,识别出其中的高频旋回周期,并选择其中7口井以短偏心率周期曲线作为五级层序划分的参考曲线,对沙三中层序进行高分辨率地层划分与对比,建立了在全区统一的高分辨率年代地层格架。更多还原

【Abstract】 As the most typical hydrocarbon accumulation zone in East China, Dongying Depression has kept new discoveries in recent decades and shows great potential for oil and gas resources. At the same time, with the deepening of exploration degree and increasing of exploration difficulty, subtle reserviors gradually change as the main exploration targets, and the 3rd and 4th member of Shahejie Formation is the most important layer that subtle reserviors developed in. On the other hand, a series of theories and technical methods for subtle reserviors exploration have been an unprecedented developed and success greatly in the exploration practice. But more refined strata classification subject to many restrictions like that strong tectonic activity, complex lithologic formation mechanism and distribution and incomplete stratigraphic cycle records of continental rift basin. High frequency cycles study provided a new way to this issue, the complete seismic and core and log and test data in Dongying Depression provided strong data protection and a higher degree of previous study also had laid a solid foundation.For controlling factors are complicated and be lack of continued profile, the study of high frequency cycle of continental basins is obviously lagging to marine basins. The 4th to 3rd member of Shahejie formation in Dongying depression experienced distinguished change of climate. And it is sure to contain the information of Milankovitch cycle. In this paper, The 4rth to the 3rd member of Shahejie formation where hydrocarbon accumulation mostly developed is chosen as the formation of interest. And GR data which is closely related with climate changes was chosen as the study object. After the environmental correction and standardization process, using sequence stratigraphy and sedimentology and Milankovitch cyclostratigraphy theory and method to make a system study on high frequence cycle, obtained the following results and conclusions:1. With the data including well core, seismic data and well logging data,4 sequence boundary of 3rd order has been recognized in the Es4s to Es3z member. Based on these boundaries, the stratigraphic sequence framework has been set up and the features of depositional systems of sequences have been released. Moreover, this paper also analyzed the effects of climate towards the sedimentary characteristics.2. This study calculated the earth orbit parameters during 30-50Ma in Dongying Depression with the La (2004) solutions. Based on the parameters, the method of spectrum analysis and wavelet analysis has been used to figure out the cycles for the eccentricity, gradient and precession. The results showed that:in 30-40Ma the eccentricity cycles mainly lie in 405ka, 124ka,95ka and the gradient cycles are mainly of 52ka,40ka and 39ka while during 40-50Ma, the eccentricity cycles are majorly of 405ka,125ka,96ka and the gradient cycles are 51ka,40ka, 38ka. Yet, the precession cycles are both of 23ka,22ka and 19ka. Furthermore, the curve of variation in theory has been computed and the ratios for the cycles during 30-40Ma and 40-50Ma have been calculated.3.After the correction and nomalization of the Es4s-Es3z GR data, spectral and wavelet analysis showed that Es4s was dominated by obliquity 40ka, however Es3x and Es3z were controlled by eccentricity 405ka and 125ka significantly.4. This study tuned the high frequency cycles in the Es4s to Es3z formation and selected the key curves of Milankovitch cycles in formation. It turned out that the cycle for Es4s member is 40ka and there are 34.5 obliquity cycles in total; the cycle for Es3x member is 405ka and there are 4.5 long eccentricity cycles in all; for Es3z member, there are about 40 short eccentricity cycles and the main cycle is 125ka.Then, the high frequency astronomical time scale for each formation has been established, leading to the more accurate geological time for each boundary and depth.5.Under the control of stratigraphic framework, according to the seismic and core and well logging data, the Dongying delta was divided into 9 periods named Z1-Z9, based on the sliding windows of spectral analysis the sedimentary rates of each period in the Es3z increased first and then decreased upwards, Z4 reached the maxmum 0.127m/ka at the most prosperous period of delta prograding. Finally the duration of each period and more accurate geological age of the interfaces were calculated on the basis of the sedimentary rates.This paper analyzed the average depositional rate of the Es4s and Es3x formation by sliding spectrum analysis, using the window of 100m and the step length,50m. The result showed the average depositional rate was O.llm/ka,0.19m/ka for Es4s and Es3x member separately. Moreover, the paper calculated the lasting time for each window.6. Take the strata 100m above and below the bottom boundary for instance, with the depositional rate data referred, this paper converted depth domain to time domain and gained the time series. The sequence was later analyzed with the tools of spectrum analysis and wavelet analysis and lead to the results that in the 50m strata above the base of Sha3 formation there were cycles of 12.06ka,11.29ka,7.94ka and 6.6ka, of which the cycle 11.29ka is the most dependable. In correspondence, the cycles of 11.7ka,8.35ka,6.5ka and 5.85ka were released from the 50 strata at the bottom of the lower Sha3 formation, with credibility of more than 99%.7. This paper studied the GR data from 10 wells in EW and NS sections that ran through the entire basin and recognized the high frequency cycles with spectrum analysis and wavelet analysis. By selecting 7 wells and setting their short cycles of eccentricity as reference for classifying the 5th sequence, this paper divided the high frequency cycles of Es3z member and made comparisons of them and then established the unified high-precision stratigraphic framework for the entire study area.更多还原