常温压条件下六种变质程度煤的超声弹性特征  

Ultrasonic elastic characteristics of six kinds of metamorphic coals in China under room temperature and pressure conditions

作　　者：王赟[1] 许小凯[2] 张玉贵[3] 

机构地区：[1]中国地质大学(北京)地球物理与信息技术学院,地质过程与矿产资源国家重点实验室,北京100083 [2]中国矿业大学(北京)地球科学与测绘工程学院,北京100083 [3]河南理工大学瓦斯地质研究所,河南焦作454000

出　　处：《地球物理学报》2016年第7期2726-2738,共13页Chinese Journal of Geophysics

基　　金：自然科学基金项目(41425017;41374131;41574126;41504107);中国石油天然气集团公司"弹性波地震成像技术合作研发"项目;中国科学院仪器装备专项"高温高压条件下含油气流体多相态岩石弹性波测量系统"(YZ201207)联合资助

摘　　要：煤弹性是反映煤的物质组分和结构的重要力学特征之一.在钻孔与测井的约束下,运用地震勘探获取煤层的弹性特征以反映其物性等,对于煤炭井工开采和煤层气储层评价及开发具有重要的工程意义,而其中,煤样的超声实验是实现地震反演煤层物性的基础.鉴于此,本文针对中国义马、阜康、淮南、平顶山、鹤壁和焦作6个矿区采集的6种不同变质程度的原煤样30块,在常温常压条件下分别进行了沿煤层走向、倾向及垂直层理三个方向煤样的实验室超声波测量.测试结果显示:煤样纵横波速度在走向、倾向、垂向三个方向上依次减小,存在各向异性,且P波速度的平均各向异性强于S波;品质因子与弹性模量在三个方向上也存在较大差异,且S波的品质因子大于P波的品质因子;弹性模量除泊松比外,均小于一般的沉积岩.通过本实验与分析进一步证明了:Gardener与Castagna公式不适用于中国煤田的煤岩弹性描述,并给出了精度更高的经验公式.Coal elasticity is one of the important mechanical characteristics reflecting the material composition and structure of coal. Under the constraint of drilling and well logging, it would be of important engineering significance for coal mining and CBM reservoir evaluation and development applying seismic exploration to acquire the elastic characteristics of the coal seams. In this regard, ultrasonic experiment of coal samples is the basis to realize the seismic inversion of physical properties of coal seam. In this paper, based on 30 pieces of six kinds of metamorphic raw coals, collected from six mining areas of Yima, Fukang, Huainan, Pingdingshan, Hebi, and Jiaozuo in China, laboratory ultrasonic measurements of these coal samples were respectively conducted in three directions of strike, dip, and perpendicular to the beddings of coal seam under room temperature and pressure. The experimental results show.the samplesp velocities of both pressure wave （P-wave） and shear wave （S-wave） decrease in turn in the three directions; there are obvious anisotropies of velocities, and the average anisotropy of P-wave velocity is stronger than S-waver s. Moreover, larger differences exist among both quality factors and modules of elasticity in the three directions, and the S-wave quality factors are greater than P-waver＇s;with exception of Poissonrs ratio, modules of elasticity of coal are less than those common sedimentary rocks. Through the experiment and analysis, it can be demonstrated that Gardener and Castagna formulas are not suitable to represent relations of coal elastic parameters in Chinds coal fields, and two empirical formulas with higher precision are statistically given.

关 键 词：煤 变质程度 超声测量 纵波 横波 

分 类 号：P631[天文地球—地质矿产勘探]