School of Geologic Engineering and Geomatics,Chang'an University Key Lab of Coal Resources Exploration andComprehensive Utilization,Ministry of Land and Resources Geophysical Survey Team,Shaanxi Provincial CoalfieldGeological Bureau Sulige Gas Field Research Center,CNPC Changqing Oilfield Branch National Engineering Labof Low Permeability Oil and Gas Field Exploration and Development Oil and Gas Exploration Company,Shaanxi Yanchang Petroleum( Group) Corporation Limited

为了研究AVO反演在煤层气勘探中对地震资料偏移距的要求,以正演模拟为研究手段,根据钻井、测井数据和地震勘探解释成果,建立了普遍适用的煤层气储层地质模型,应用Zoeppritz方程组弹性模量近似式,计算出其各项系数对入射角的梯度。理论模型的正演模拟表明,将AVO反演应用于煤层气勘探时,地震资料的最大偏移距应当保证最大入射角接近或等于反射系数对入射角梯度极值对应的入射角。通过对实际钻井资料进行AVO模拟,结果表明在煤层气勘探中应用AVO反演,地震资料的最大偏移距只要接近、等于或略大于目的层深度,就可以反映振幅随偏移距变化的特征,足以满足煤层气勘探中AVO反演对地震资料偏移距的要求。

in order to study the requirement of the AVO Inversion to the offet distance of theseisnic information from the calbed metane explorationwith the for ward simulation as the study means .according to thedrlling and logging data and the seismic exploraion exlained achie vements a general aproprae geologcal madel of the cal bed methane reservoir was establis hed and with the elastic mocdulus approximate fomua ofthe zoepprizeEquations appi ,.the inciden angle grdcientof each coefficient was calculated.The forward sinmulation of the theoretcal model showed that when the A.V0 Inverston as aplied o thecalbt d methane sxplrton,a max ofiset distance of the seismic information should ensure the max refracion average angle cose to or equal tothe refraction average angle relevant to the reraction average angle gradient of the refecion c. icient.with the acual driling information appied to conduct the AvO Simuation.the resiulis showed thathe AV/O lmversion applied to the coal bed methane exploration, when the max ofoset distance of the seismic information cose toequal o lit e higher than the taget stratum depthcould refect the featuresof the amplitude with the ofiset varied and couldfully met the requrements of the Av/O Imversion to theofeset distance of the s ismic information from the coalbed methane exploration.