Numerical analysis of the effect of natural microcracks on the supercritical CO2 fracturing crack network of shale rock based on bonded particle models

The problem of predicting the geometric structure of induced fractures is highly complex and significant in the fracturing stimulation of rock reservoirs. In the traditional continuous fracturing models, the mechanical properties of reservoir rock are input as macroscopic quantities. These models neglect the microcracks and discontinuous characteristics of rock, which are important factors influencing the geometric structure of the induced fractures. In this paper, we simulate supercritical CO₂ fracturing based on the bonded particle model to investigate the effect of original natural microcracks on the induced‐fracture network distribution. The microcracks are simulated explicitly as broken bonds that form and coalesce into macroscopic fractures in the supercritical CO₂ fracturing process. A calculation method for the distribution uniformity index (DUI) is proposed. The influence of the total number and DUI of initial microcracks on the mechanical properties of the rock sample is studied. The DUI of the induced fractures of supercritical CO₂ fracturing and hydraulic fracturing for different DUIs of initial microcracks are compared, holding other conditions constant. The sensitivity of the DUI of the induced fractures to that of initial natural microcracks under different horizontal stress ratios is also probed. The numerical results indicate that the distribution of induced fractures of supercritical CO₂ fracturing is more uniform than that of common hydraulic fracturing when the horizontal stress ratio is small.     

Parallelization of the distinct lattice spring model

The distinct lattice spring model (DLSM) is a newly developed numerical tool for modeling rock dynamics problems, i.e. dynamic failure and wave propagation. In this paper, parallelization of DLSM is presented. With the development of parallel computing technologies in both hardware and software, parallelization of a code is becoming easier than before. There are many available choices now. In this paper, Open Multi‐Processing (OpenMP) with multicore personal computer (PC) and message passing interface (MPI) with cluster are selected as the environments to parallelize DLSM. Performances of these parallel DLSM codes are tested on different computers. It is found that the parallel DLSM code with OpenMP can reach a maximum speed‐up of 4.68× on a quad‐core PC. The parallel DLSM code with MPI can achieve a speed‐up of 40.886× when 256 CPUs are used on a cluster. At the end of this paper, a high‐resolution model with four million particles, which is too big to handle by the serial code, is simulated by using the parallel DLSM code on a cluster. It is concluded that the parallelization of DLSM is successful. Copyright © 2011 John Wiley & Sons, Ltd.     

Storm Deposits of the Sinian Zhangqu Formation in Northern Anhui — An Upward Shallowing Carbonate Sequence1

Abstract This paper studies, for the first time, the storm deposits of a carbonate sequence in the Sinian Zhangqu Formation in northern Anhui. In the formation, a great number of calcareous trider sponge spicules were discovered in a distal storm turbidity sequence, which have provided further evidence for the correlation of the Sinian Systems in North and South China from a view point of palaeontology.     

上海及其邻区潜在地质灾害的构造背景与成因机理

本文基于上海及其邻区活动断裂构造及有关地区潜在地质灾害特点的研究,论证了上海及其邻区潜在地质灾害的三种基本类型及其构造背景与成因机理;指出:上海及其邻区楔形断裂系统的存在与活动是诱发有关地区潜在地质灾害的主导因素。文中明确指出了上海及其邻区楔形断裂系统的研究在相关地区进行潜在地质灾害评价与预测方面的应用前景与发展方向。     

丹霞风景名胜区的旅游开发研究

本文以丹霞地貌、区域文化开发、景观美学、景观资源的保护和利用、旅游业开发等专题研究及区域旅游发展战略理论研究为基础,与风景旅游规划相结合,研究了自然景观和人文景观、景观资源综合评价和旅游开发总体规划等问题。据此研究成果上报,该风景区已被批准为第二批国家重点风景名胜区。     

内蒙古狼山地区的层控铀矿及其控制因素的卫片影象模式

狼山地区广泛分布着花岗岩型铀矿化和砂岩型铀矿化。本文通过对该区的遥感地质综合解译,重点研究了几个含铀盆地的砂岩型铀矿化成矿特点及其通感图象的影象特征,发现广布于早白垩世断陷盆地的砂岩型铀矿化是一典型的层控型铀矿。并通过区域构造型式的研究,强调了弧形构造的断块活动特征及其对含铀盆地和含矿层分布的控制作用;揭示了弧形构造的后期活动和环形构造、北北东向线性构造与铀矿化的再造关系。从而得出砂岩铀矿化是受地层岩相和弧、环、线构造“四位一体”条件控制的新认识。该矿化在MSS图象上呈现一定的影象特征,据此,本文概括出本区层控铀矿的影象模式。     

上海地区深部构造特征和地震活动趋势探讨

本文介绍由重磁资料计算上海地区居里面、莫霍面、均衡重力异常及地幔流应力场的方法和成果,并在对成果初步分析的基础上,探讨了深部地质构造特征及其与地震活动趋势的关系,其中着重讨论了居里面及其与地震活动的关系。文章最后提出了对上海地区地震活动趋势的几点认识。     

中国地震科技文献数据库(英文版)

本文全面地描述了中国地震科技文献数据库(英文版)。该库在VAX 11/750小型计算机上,使用VAX数据检索、VAX公共数据字典软件进行设计。是一个联机检索系统。文献库收集五十余种中国编辑出版的科技期刊中,有关地震预报研究的论文。参考国內外文献著录准则,使文献记录格式标准化,通用化。一条记录长1898字节,其中文摘长1020字节。每年文献量约800余条。文献库磁带和软盘拷贝在国内外交换与出售。