School of Geosciences & Surveying Engineering,China University of Mining and Technology⁃Beijing
State Key Laboratory of CoalResources and Safe Mining,China University of Mining and Technology⁃Beijing

研究煤弹性参数的影响因素可以揭示煤层AVO响应的物理含义,有利于指导复杂地质条件下的煤层气勘探。以沁水盆地寺河矿区3号煤层的60块煤样为研究对象,根据煤的工业成分分析、矿物成分分析和地层条件下测试结果,基于BET多层吸附理论(TheBrunauer-Emmett-Tellertheory)和自洽模型构建不同流体饱和的煤层气储层岩石物理模型。主要考虑3种流体饱和情况:1种为完全水饱和,另外2种为不同的含水、吸附气和游离气的多相混合流体。在此基础上,分析煤基质组成、孔隙率和流体饱和情况对煤的弹性参数的综合影响,进一步开展含煤地层在不同孔隙率、不同流体饱和情况下的地震AVO响应特征分析。结果表明:研究区内,煤的孔隙率是引起煤纵横波速度、多相流体饱和煤体积模量变化的主要影响因素,且孔隙率增大引起多相流体饱和煤体积模量的变化较明显;相比于孔隙率,不同煤基质组成对完全水饱和煤体积模量、密度的影响更为显著;不同流体饱和情况引起的煤弹性参数变化相较于孔隙率、煤基质组成小。分析含煤地层的AVO响应特征可以发现,孔隙率与AVO属性呈一定线性关系,含水饱和度与AVO属性呈一定非线性关系;与其他AVO属性相比,横波阻抗属性在不同孔隙率、不同流体饱和情况下的地震AVO响应最为显著。

The study of the influence factors of coal elastic parameters can reveal the physical meaning of the AVO re⁃sponse of coalbed,which is beneficial to guide the exploration of coalbed methane in complex geological conditions.The 60 coal samples from the No.3 coalbed in the Sihe coalmine of the Qinshui Basin were used for the study. Accord⁃ing to the industrial composition analysis,mineral composition analysis and logging data of the coal,various differentfluid⁃saturated rock physics models of coalbed methane(CBM)reservoir were constructed based on the BET multilayeradsorption theory and self⁃consistent model. These models mainly consider three types of fluids,one is completely wa⁃ter⁃saturated,and the other two are multiphase mixed fluids with different water contents,adsorbed gas and free gas. U⁃sing the models,the authors analyzed the comprehensive effects of CBM reservoir characteristics such as coal ma⁃trix composition,porosity and fluid type on the elastic parameters of coal,and further analyzed the seismic AVO re⁃sponse characteristics of coalbed under different porosity and fluid types. In the research area,the porosity of coalis the main influencing factor for the change of P⁃wave and S⁃wave velocity of coal and bulk modulus of multiphasefluid⁃saturated coal. And the increase of porosity causes a significant change in the bulk modulus of multiphase fluid⁃saturated coal. Compared with the porosity, the effect of different coal matrix composition on the bulk modulusand density of completely water⁃saturated coal is more significant. In addition, the change of elastic parametersof coal caused by different fluid types is small compared to porosity and coal matrix composition. By analyzing theAVO response characteristics of coalbed,it can be found that the porosity has a certain linear relationship with theAVO attributes,and the water saturation has a certain nonlinear relationship with the AVO attributes. The S⁃wave im⁃pedance attribute responds most significantly in different porosity and different fluid saturation conditions.

国家自然科学基金资助项目(42274165);国家重点研发计划资助项目(2018YFC0807803);煤炭资源与安全开采国家重点实验室开题课题资助项目(SKLCRSM20KFA07)

吴雨珊,邹冠贵,曾葫,等. 煤弹性参数的影响因素分析及其 AVO 响应特征[J].煤炭学报,2023,48(S1):194-208.

WU Yushan,ZOU Guangui,ZENG Hu,et al. Analysis of influence factors of coal elastic parameters andits AVOresponse characteristics [J]. Journal of China Coal Society,2023,48(S1):194-208