Integrated erosion control measures and environmental effects in rocky mountainous areas in northern China

Based on observations of runoff plots and field investigations of gully cross-sections, impacts of various soil and water conservation measures on runoff and sediment yield are analyzed for different rainfall conditions. The results show that antecedent rainfall and rainfall intensity are the main factors affecting the runoff and soil erosion processes. Rainfall events with antecedent rainfall can produce high runoff and sediment yield. Large differences in the characteristics of two rainfall events will result in greater variations of total runoff and sediment yield from the same runoff plot. Under the same soil control measure and rainfall condition, soil and water conservation measures can reduce the impacts of antecedent rainfall and rainfall intensity on runoff and soil erosion. Among various measures, level terrace seems to be the greatest for soil conservation purposes. Combining with engineering measures,Vegetation measures is also effective in controlling runoff and soil erosion. In the initial stage of vegetation enclosure measures, engineering measure is necessary to improve the environment for ecological recovery. Gully head protection can control gully erosion effectively, but the effectiveness of gully head protection would be reduced when rainfall intensity increases. Therefore, the design of a gully head protection structure must be based on local hydrological conditions.     

汶川8.0级大地震前电磁扰动异常变化特征初步研究

利用电磁波扰动理论,研究汶川5·12大地震前,金河、剑阁、二砂3个台站的电磁波异常变化特征。结果表明:①震前3个台站均出现电磁扰动异常,以金河、剑阁地震台显著;②电磁扰动前兆异常在时间进程上有明显的阶段性变化;③随距震中距半径的增大,电磁扰动值逐步衰减。     

Generalized anisotropy parameters and approximations of attenuations and velocities in viscoelastic media of arbitrary anisotropy type – theoretical and experimental aspects*

Seismic anisotropy in geological media is now widely accepted. Parametrizations and explicit approximations for the velocities in such media, considered as purely elastic and moderately anisotropic, are now standards and have even been extended to arbitrary types of anisotropy. In the case of attenuating media, some authors have also recently published different parametrizations and velocity and attenuation approximations in viscoelastic anisotropic media of particular symmetry type (e.g., transversely isotropic or orthorhombic). This paper extends such work to media of arbitrary anisotropy type, that is to say to triclinic media. In the case of homogeneous waves and using the so‐called ‘correspondence principle’, it is shown that the viscoelastic equations (for the phase velocities, phase slownesses, moduli, wavenumbers, etc.) are formally identical to the corresponding purely elastic equations available in the literature provided that all the corresponding quantities are complex (except the unit vector in the propagation direction that remains real). In contrast to previous work, the new parametrization uses complex anisotropy parameters and constitutes a simple extension to viscoelastic media of previous work dealing with non‐attenuating elastic media of arbitrary anisotropy type. We make the link between these new complex anisotropy parameters and measurable parameters, as well as with previously published anisotropy parameters, demonstrating the usefulness of the new parametrization. We compute the explicit complete directional dependence of the exact and of the approximate (first and higher‐order perturbation) complex phase velocities of the three body waves (qP, qS1 and qS2). The exact equations are successfully compared with the ultrasonic phase velocities and phase attenuations of the three body waves measured in a strongly attenuating water‐saturated sample of Vosges sandstone exhibiting moderate velocity anisotropy but very strong attenuation anisotropy. The approximate formulas are checked on experimental data. Compared to the exact solutions, the errors observed on the first‐order approximate velocities are small (<1%) for qP‐waves and moderate (<10%) for qS‐waves. The corresponding errors on the quality factor Q are moderate (<6%) for qP‐waves but critically large (up to 160%) for the qS‐waves. The use of higher‐order approximations substantially improves the accuracy, for instance typical maximum relative errors do not exceed 0.06% on all the velocities and 0.6% on all the quality factors Q, for third‐order approximations. All the results obtained on other rock samples confirm the results obtained on this rock. The simplicity of the derivations and the generality of the results are striking and particularly convenient for practical applications.     

基于双相介质理论的储层参数反演方法

传统基于单相介质理论的储层参数反演方法将孔隙流体与固体骨架等效为单一固体,弱化了孔隙流体的影响,反演结果精度不高.本文提出根据双相介质理论反演储层参数的方法.首先,在前人研究的基础上,利用岩石物理模型建立弹性参数与孔隙度、饱和度、泥质含量等储层参数间的关系,进而将双相介质反射系数推导为储层参数的函数;其次,根据贝叶斯反演理论,在高斯噪声假设的基础上,采用更加符合实际情况的修正柯西分布函数描述反射系数的稀疏性,推导出储层物性参数目标反演函数;最后,应用差分进化非线性全局寻优算法来求解目标反演函数,使得反演结果与实际资料间误差最小.新方法旨在突出流体对介质反射系数的影响,以期得到较高的储层参数反演精度.模型与实际资料测试均表明该方法可行、有效且反演精度较高.     

裂缝型储层流体识别方法

裂缝型储层的描述包括预测裂缝分布特征和识别裂隙充填物.依据等效介质理论计算的纵波速度随裂缝密度的增大而减小.正演地震记录显示,裂缝介质含气时反射振幅最大,且变化程度比含油或含水时大.叠前方位AVO反演所得的各向异性梯度Bani与裂缝密度成正比,可用于描述有效裂缝发育强度.对于不同的裂缝密度,各向异性梯度Bani与各向同性梯度Biso的比值I(1)fluid近似为常数,且对流体敏感.经裂缝纵横比和背景介质拉梅常数修正后,流体因子Ifluid既不随纵横比变化,又不受背景介质的影响,是裂缝型储层敏感的流体识别因子.在塔里木盆地塔北哈拉哈塘地区热瓦普区块碳酸盐岩储层裂缝发育区域,运用该参数在井点处的流体识别效果与钻井结果一致.     

Effect of micro‐inhomogeneity on the effective stress coefficients and undrained bulk modulus of a poroelastic medium: a double spherical shell model

Although most rocks are complex multi‐mineralic aggregates, quantitative interpretation workflows usually ignore this complexity and employ Gassmann equation and effective stress laws that assume a micro‐homogeneous (mono‐mineralic) rock. Even though the Gassmann theory and effective stress concepts have been generalized to micro‐inhomogeneous rocks, they are seldom if at all used in practice because they require a greater number of parameters, which are difficult to measure or infer from data. Furthermore, the magnitude of the effect of micro‐heterogeneity on fluid substitution and on effective stress coefficients is poorly understood. In particular, it is an open question whether deviations of the experimentally measurements of the effective stress coefficients for drained and undrained elastic moduli from theoretical predictions can be explained by the effect of micro‐heterogeneity. In an attempt to bridge this gap, we consider an idealized model of a micro‐inhomogeneous medium: a Hashin assemblage of double spherical shells. Each shell consists of a spherical pore surrounded by two concentric spherical layers of two different isotropic minerals. By analyzing the exact solution of this problem, we show that the results are exactly consistent with the equations of Brown and Korringa (which represent an extension of Gassmann's equation to micro‐inhomogeneous media). We also show that the effective stress coefficients for bulk volume α, for porosity n_? and for drained and undrained moduli are quite sensitive to the degree of heterogeneity (contrast between the moduli of the two mineral components). For instance, while for micro‐homogeneous rocks the theory gives n_? = 1, for strongly micro‐inhomogenous rocks, n_? may span a range of values from –∞ to ∞ (depending on the contrast between moduli of inner and outer shells). Furthermore, the effective stress coefficient for pore volume (Biot–Willis coefficient) α can be smaller than the porosity ?. Further studies are required to understand the applicability of the results to realistic rock geometries.     

中强地震前周至台地电阻率的异常变化

通过对三个震例的分析,笔者得到了周至台地电阻率观测在地震发生前出现的一些异常变化。其具体表现为:1在汶川地震发生前,周至台地电阻率观测在三个测向的日均值都呈缓慢下降,幅度为1.0%—3.9%,从异常变化出现至发震的时间间隔为1月左右。2在芦山地震和岷县漳县地震发生前,从2011年9月开始,周至台地电阻率观测在三个测向的日均值都呈显著下降且幅度较大。其中,芦山地震发生在异常变化恢复(上升)的过程中,从出现异常到发震的间隔为16个月;而岷县漳县地震也发生在异常恢复(上升)的过程中,但从异常出现到发震的间隔为19个月。表明周至台地电阻率观测能较好地反映出地震的前兆信息,具有一定的映震能力,这对陕西及相邻地区的地震监测和预报可以起到一定的作用。     

The black hole mass–stellar velocity dispersion correlation: bulges versus pseudo-bulges

We investigate the correlation between the supermassive black holes (SMBHs) mass ( M _bh) and the stellar velocity dispersion  (σ_*)  in two types of host galaxies: the early-type bulges (disc galaxies with classical bulges or elliptical galaxies) and pseudo-bulges. In the form  log ( M _bh/M_⊙) =α+β log (σ_*/200 km s⁻¹)  , the best-fitting results for the 39 early-type bulges are the slope  β= 4.06 ± 0.28  and the normalization  α= 8.28 ± 0.05  ; the best-fitting results for the nine pseudo-bulges are  β= 4.5 ± 1.3  and  α= 7.50 ± 0.18  . Both relations have intrinsic scatter in  log  M _bh  of ≲0.27 dex. The   M _bh–σ_*  relation for pseudo-bulges is different from the relation in the early-type bulges over the 3σ significance level. The contrasting relations indicate the formation and growth histories of SMBHs depend on their host type. The discrepancy between the slope of the   M _bh–σ_*  relations using different definition of velocity dispersion vanishes in our sample, a uniform slope will constrain the coevolution theories of the SMBHs and their host galaxies more effectively. We also find the slope for the 'core' elliptical galaxies at the high-mass range of the relation appears steeper  (β≃ 5–6)  , which may be the imprint of their origin of dissipationless mergers.     

一种评价致密砂岩储层孔隙结构的新方法及其应用(英文)

致密砂岩储层的孔隙结构对其渗透性和电性影响显著,是此类复杂储层岩石物理研究的关键。针对仅从连通喉道半径评价渗透率的多解性以及储层孔隙结构与电性关系研究欠缺等不足,综合影响物性的主要因素,提出了一种同时考虑孔隙度、最大连通喉道半径及分选性三种因素的新型孔隙结构参数δ的计算公式。利用岩心及实测数据对比分析表明,δ值能够较连通喉道半径等传统方法更精确地刻画致密砂岩储层渗透性,同时它与储层电性具有密切关系,可用于估算地层因素F和胶结指数m。据此提出将孔隙结构对电阻率的影响进行归一化校正以及基于核磁共振测井预测储层完全含水电阻率R0的评价方法,从而突出储层流体性质变化引起的电性变化,并提供了一种新的致密砂岩储层流体识别思路,研究结果得到了实验资料和实际测井试油资料的验证。     

吉林省洮南市聚宝铜矿床的地质特征、流体包裹体研究

吉林省洮南市聚宝铜矿床位于布敦花-长春岭构造成矿带上。矿区发现3个矿脉组,蚀变闪长玢岩和近南北向的断裂控制铜矿产出与分布。矿石矿物主要为黄铜矿、黄铁矿和辉铜矿,伴生金银。矿石以交代溶蚀结构和脉状、浸染状构造为特征。该矿床划分为4个成矿阶段：黄铁矿阶段、黄铜矿阶段、多金属阶段和碳酸盐阶段。流体包裹体研究表明,该矿床流体包裹体由气液两相和含子矿物三相包裹体组成。气液两相包裹体大小为6~8 μm,气液比为10%~20%,均一温度为163.8~364.0 ℃,多数为180~240 ℃,盐度（w(NaCl)）为1.05%~10.62%;含子矿物三相包裹体大小为5~10 μm,气液比为3%~6%,均一温度为270~367 ℃,w(NaCl)为35.89%~42.85%。流体包裹体密度为0.56~1.08 g/cm³,估算成矿压力为11.71~42.91 MPa,深度为1.12~3.0 km。初步确定该矿床为中温岩浆热液铜矿床,成矿与闪长玢岩有成因联系。