【作者】 张西娟；

【导师】 马寅生； 赵志中； 陈正乐；

【作者基本信息】 中国地质科学院 ， 构造地质学， 2007， 博士

【摘要】 柴达木盆地北缘(简称柴北缘)地区是柴达木盆地三个主要油气分布区之一,但由于该地区地质构造复杂,地震资料品质相对较差,加之海拔较高,自然环境恶劣,从而导致对该地区的地质构造认识存在很大的分歧,对油气形成和运聚规律研究不够深入,使得探明的储量与资源潜力不甚相称。因此,论文从柴北缘地区中新生代构造变形特征和构造应力测量入手,通过模拟来分析该地区的应力场特征,并探讨应力与油气勘探和开发的关系。与其它盆地相比,柴北缘中西段地区地面构造非常发育,因此论文论述了研究区的断裂和褶皱发育特征,着重对柴北缘断裂带进行了野外调查和测年分析。在对前人资料研究的基础上,通过野外调查和测年测试,论证了该断裂带的运动方式。另外,在对柴北缘中西段地区构造特征进行分析的基础上,介绍了该地区的构造样式和新构造发育特征,并简单的探讨了其与油气藏的关系。在构造应力研究方面,运用磁组构、声发射、水力压裂等方法,结合震源机制解、GPS资料、构造分析等多种方法,探讨了该地区中新生代的应力特征。根据应力测量和地质资料,建立了柴北缘地区中西段T2和T4的地震反射层地质构造模型,并对这两个模型分别进行了光弹模拟和弹塑性数值模拟。对模拟结果进行比较认为,两者的模拟结果有一定的可比性,证明了数值模型比较适合。但由于数值模拟考虑了材料的影响,因此导致了在部分细节上,两者存在不同程度的差异。为了更深入的了解柴北缘地区的应力分布状况,选择构造相对简单的昆特依凹陷进行了三维的应力场模拟。模拟结果显示,各层位的空间分布特征及其断层的走向对应力场的影响较为显著。在研究地区,4600米深度范围以下,重力引起的垂向应力变成了最大主压应力,而在4600米以上,最大主应力为水平方向,但最小主应力的方向发生了互换,在400～700m深度范围内,最小主应力的方向是垂直方向的,在在1100～3500m的深度范围内,中间主应力方向则变为垂直向。而对昆2井及其周边地区建立了子模型进行模拟的结果显示,在距井壁3～7倍的地方,垂向应力变化相对较小,但水平应力则发生了不同程度和趋势的变化,另外,最小应力分量的方向与远源加载的压力在南东向发生了较大的偏转。最后,运用模拟得到的结果,尝试性地分析了昆特依凹陷地区的流体势分布特征、裂缝发育情况、昆1断层带的封闭性及昆2井的井壁稳定性。分析结果显示,昆2井及其附近地区为该凹陷的有利成藏地区,且昆1断裂带的封闭性较好,昆2井地区井壁较为稳定。更多还原

【Abstract】 The northern fringe of Qaidam Basin(abbr. northern Qaidam ) is one of the three principal oil-gas bearing provinces in Qaidam Basin. However, due to the complicated geological structure and poor quality of seismic materials, as well as high elevation and bad natural environment, there exist large divergence with the geological structure in this region, and the rule of hydrocarbon generation, migration and accumulation is not well understood, which make the proven reserves unbalanced with its resource potential. Therefore, the thesis starts from the tectonic deformation characteristics and structural stress measurement in Meso-Cenozoic era in northern Qaidam, and analyzes the stress field character of this region by means of simulation, and further discusses the relationship between the stress field and the exploration and development of the oil-gas bearing provinces.In contrast with other basins, the ground structural features in the mid-west region of Qaidam Basin are well developed. The thesis discusses the developing characters of the fault and fold in the region, and makes an emphasis on the northern Qaidam fault zone by field investigations and dating techniques. Moreover, based on the analysis of tectonic characteristics in mid-west region, the author introduces the tectonic style and neotectonic development characters, and further discusses the relationship between tectonic characters and the oil-gas.With regard to the tectonic stress study, making use of many methods, such as magnetic fabric, acoustic emission and hydraulic fracture, and combining with focal mechanism solution, GPS data and tectonic analysis, the thesis discusses the Meso-Cenozoic stress field characteristics in this region. Based on the stress measurement data and geological materials, the geological structure models are set up for T2 and T4 seismic reflection layers of the mid-west region of Qaidam Basin. Photoelastic simulation and plastic-elastic numerical simulation were carried out in terms of those two models. The results comparison between photoelastic and numerical simulations indicate that those two methods have certain comparability, and consequently prove that numerical simulation is appropriate to tectonic stress field analysis. However, because the numerical model takes the material influence into account, the later results in difference to some extent of those two models in details.In order to further understand the stress distribution conditions in northern Qaidam Basin, the three-dimensional stress simulation is carried out in Kunteyi depression where the tectonics is relatively simple. The simulation results indicate that the spacial distribution characteristics of each reflection layer and the fault strike make relatively remarkable emphasis on the stress. In the research area, the vertical stress resulting from the gravity becomes the maximal principal stress in the section more than 4600 meters in depth scope, while in the section less than 4600 meters in depth scope, the maximal principal stress is horizontal and takes place interchange with the minimal principal stress in the direction. In the depth scope ranging from 400 meters to 700 meters, the direction of the minimal principal stress is vertical. In the depth scope ranging from 1100 meters to 3500 meters, the direction of the middle principal stress becomes vertical.The simulation result, from the modelling of the Kun 2# drill and its vicinities, suggests that the vertical stress variation is relatively small in the place 3 to 7 times of the drill diameter from the well wall, but the horizontal stress varies in some trend. Moreover, the direction of the minimal stress component and the remote loading pressure take place large deviation in southeast direction. Lastly, utilizing the simulation result, the author tries to analyze the distributional characteristics of fluid potential, fracture development, sealing of Kun 1# fault and the drill wall stability of Kun 2# well. The analysis result shows that Kun 2# well and its vicinities is the beneficial oil-gas bearing province in Kunyite depression, and the sealing of Kun 1# fault zone is well, and the well wall in Kun 2# well region is relatively stable.更多还原