基于恒速压汞技术研究页岩气储层孔隙结构:以湘西北地区五峰组页岩为例     

王静 《地质与勘探》2021,57(2):450-456

页岩气储层孔隙结构是页岩气富集成藏、储层评价和优选有利区的关键参数,区分孔隙和喉道是表征页岩气储层孔隙结构的关键。本文选择4块具有不同渗透率的湘西北地区奥陶系五峰组页岩为研究对象,基于恒速压汞实验讨论孔隙和喉道的大小、分布特征及其相互关系以及与渗透率的联系。结果表明:具有不同渗透率的页岩样品表现为较为相近的孔径分布特征但差异较大的喉道分布特征。页岩样品渗透率的大小与孔隙半径没有明显相关关系;喉道大小及其分布特征是控制低渗储层孔隙结构的关键要素之一。渗透率较低页岩样品的喉道以喉道半径小且集中分布为特征,而渗透率较大页岩样品的喉道以喉道半径大呈分散分布但主要以大喉道为特征。喉道特征是研究页岩气储层储集空间和吸附能力的重要部分,在以后对页岩气的勘探开发中应特别注意及重视。  相似文献   

免共振沉桩过程对地表振动影响的FLAC3D数值模拟     

魏家斌  王卫东  吴江斌 《吉林大学学报(地球科学版)》2021,51(5):1514-1522

为研究免共振沉桩过程对地表振动影响,采用密度放大法以消除模型桩弹性模量过大对计算效率的影响,在有限差分软件FLAC^3D中建立了相应的连续振动沉桩模型,并和文献中的现场测试结果进行了比较,分析了激振力幅值和振动频率这两个施工参数对地表振动响应的影响。结果表明：密度放大法可有效提高数值模拟的计算效率,模拟沉桩7.0倍桩径（4.9 m）所需计算时间约为12.0 h,数值结果较好地模拟了现场测试中免共振沉桩的地表振动影响;激振力幅值和振动频率均主要对近场（水平距离为5.0倍桩径范围内）的地表振动有明显影响;临界沉桩深度与地表振动影响峰值相对应,该深度随水平距离先增大后趋于稳定;激振力幅值对临界沉桩深度的改变不明显,振动频率对远场临界沉桩深度则有较明显影响。  相似文献   

In situ stress field of eastern Australia     

R. R. Hillis  J. R. Enever  S. D. Reynolds 《Australian Journal of Earth Sciences》2013,60(5):813-825

New in situ data based on hydraulic fracturing and overcoring have been compiled for eastern Australia, increasing from 23 to 110 the number of in situ stress analyses available for the area between and including the Bowen and Sydney Basins. The Bowen Basin displays a consistent north‐northeast maximum horizontal stress (σ_H) orientation over some 500 km. Stress orientations in the Sydney Basin are more variable than in the Bowen Basin, with areas of the Sydney Basin exhibiting north‐northeast, northeast, east‐west and bimodal σ_H orientations. Most new data indicate that the overburden stress (σ_V) is the minimum principal stress in both the Bowen and Sydney Basins. The Sydney Basin is relatively seismically active, whereas the Bowen Basin is relatively aseismic. Despite the fact that in situ stress measurements sample the stress field at shallower depth than the seismogenic zone, there is a correlation between the stress measurements and seismicity in the two areas. Mohr‐Coulomb analysis of the propensity for failure in the Sydney Basin suggests 41% of the new in situ stress data are indicative of failure, as opposed to 13% in the Bowen Basin. The multiple pre‐existing structural grains in the Sydney Basin further emphasise the difference between propensity for failure in the two areas. Previous modelling of intraplate stresses due to plate boundary forces has been less successful at predicting stress orientations in eastern than in western and central Australia. Nonetheless, stress orientation in the Bowen Basin is consistent with that predicted by modelling of stresses due to plate boundary forces. Variable stress orientations in the Sydney Basin suggest that more local sources of stress, such as those associated with the continental margin and with local structure, significantly influence stress orientation. The effect of local sources of stress may be relatively pronounced because stresses due to plate boundary forces result in low horizontal stress anisotropy in the Sydney Basin.  相似文献   

A Time-Domain Coupled Model for Nonlinear Wave Forces on A Fixed Box-Shaped Ship in A Harbor   总被引：2，自引：1，他引：1  

王大国  邹志利  谭国焕  刘霞 《中国海洋工程》2010,24(1):41-56

A 2-D time-domain numerical coupled model is developed to obtain an efficient method for nonlinear wave forces on a fixed box-shaped ship in a harbor.The domain is divided into an inner domain and an outer domain.The inner domain is the area beneath the ship and the flow is described by the simplified Euler equations.The other area is the outer domain and the flow is defined by the higher-order Boussinesq equations in order to consider the nonlinearity of the wave motions.Along the interface boundaries between the inner domain and the outer domain,the volume flux is assumed to be continuous and the wave pressures are equal.Relevant physical experiment is conducted to validate the present model.It is shown that the numerical results agree with the experimental data.Compared with the coupled model with the flow in the inner domain governed by the Laplace equation,the present coupled model is more efficient and its solution procedure is more simple,which is particularly useful for the study on the effect of the nonlinear wave forces on a fixed box-shaped ship in a large harbor.  相似文献   

Storm surge mitigation through vegetation canopies     

M. B. Danard  T. S. Murty 《Natural Hazards》1994,9(1-2):155-166

The paper of Reid and Whitaker (1976) on the effects of a vegetation canopy on flow of water is re-examined. Their assumptions on the equality of various drag coefficients are replaced by more realistic calculations. A new method for calculating wind stress on water is presented for the case when the vegetation extends above the water surface.For the case of vanishingly small water depth, it is shown that the horizontal stress is approximately constant in the vertical. This results in a diagnostic relationship for the water current as a function of the wind stress and bottom roughness.A new expression for the vertically averaged frictional force per unit mass is derived on the assumption that the friction velocity varies linearly with height. The vertical rate of change of friction velocity depends on the mean water current, the wind stress, the bottom roughness, and the water depth. This work has a possible application in the mitigation of storm surges.  相似文献   

论板块运动的驱动力          下载免费PDF全文

谢鸣一  谢鸣谦 《地质科学》1987,(3):209-220

本文从动力学的角度讨论了板块运动的驱动机理,并提出了计算板块扩张速度的公式,然后求出了不同类型板块的扩张速度。用此公式所计算出的板块扩张速度与实际观测速度很符合。  相似文献   

GPS实时精密星历确定     

张鹏 《全球定位系统》2001,26(4):9-15,38

本文基于美国Gamit软件研究的基础上，对于GPS实时精密轨道确定的方法进行了细致的研究，提出了在中国区域范围内有实用价值的区域定轨方法与方案。本文从GPS轨道的各种摄动力影响入手，对实时GPS轨道确定方法进行了阐述，同时讨论了在国家测绘局目前GPS跟踪站网的构架下，利用跟踪站网的多天数据并且引入随机参数进行GPS实时轨道确定的实例。  相似文献   

藏北高原土地沙漠化现状及其驱动机制   总被引：21，自引：0，他引：21  

董玉祥 《山地学报》2001,19(5):385-391

作为青藏高原主体的藏北高原是我国土地沙漠化三大分布区之－－青藏高原分布区的代表性地域，是研究现代土地沙漠化过程及其形成机制的重要地区。本文从沙漠化土地的类型、面积与分布等方面详细分析了藏北高原土地沙漠化的现状，定性与定量分析相结合探讨了该区现代沙漠化过程的主要影响因子及其驱动机制。研究结果表明，藏北高原是我国重要的沙漠化土地分布区、沙漠化土地面积大、类型多、程度重、分布广、危害重，其形成与发展是自然因素与人为因素、自然过程与人为过程共同作用的结果，其中气候变化是其主要驱动力。  相似文献   

东北平原西部沙地近10年的沙质荒漠化   总被引：35，自引：0，他引：35  

李宝林  周成虎 《地理学报》2001,56(3):307-315

东北平原西部沙地位于欧亚大陆中纬度巨型沙带的东部边缘，为我国沙质荒漠化土地的东缘，是我国自然环境最好的沙区，随着经济的发展，生态环境遭到严重破坏，沙质荒漠化景观日益明显，尤其是南部的科尔沁沙地，沙质荒漠化已十分严重，已经超过与其相邻的西部环境条件更差的沙区，利用RS和GIS，根据NOAA/AVHRR数据建立的沙质荒漠化监测指标，对东北平原西部沙地沙质荒膜化现代过程进行了动态监测，在此基础上利用TM数据对沙质荒漠化的发展方式与成因进行了深入的探讨，并有针对性地提出了区域沙质荒漠化的防治对策。  相似文献   

On arable land changes in Shandong Province and their driving forces   总被引：3，自引：0，他引：3  

SHAO Xiao-mei  ZHANG Hong-ye 《地理学报(英文版)》2001,11(3):329-335

IntroductionAlmost all the provinces and autonomous regions in China have experienced decrease of arable land in the processes of economic development, population growth and urbanization. The situation is more serious in Shandong Province because of the big population and being an agricultural province. From 1949 to 1999, the arable land was decreased by more than 2 million ha in this province accompanied by rapid population growth. The total population in the province in 1999 was twice of t…  相似文献