叠前弹性反演在Y研究区盐下碳酸盐岩气藏预测中的应用

Application of pre-stack elastic inversion for sub-salt gas prediction in Block Y

(1.北京大学地球与空间科学学院,北京100871；2.中国石油天然气集团公司阿姆河天然气公司,北京100101；3.中国石油天然气股份有限公司新疆油田公司勘探开发研究院地球物理研究所,新疆乌鲁木齐830011；4.中国地质大学(北京),北京100083)

Gong Xinglin,School of Earth and Space Sciences,Beijing University,Beijing 100871,China

常规叠后反演和传统的AVO技术很难有效预测Y研究区盐下碳酸盐岩气藏,因此,提出了利用叠前弹性参数反演预测该区气藏的思路。通过不同流体弹性参数的交会分析(该区岩性单一),筛选出对碳酸盐岩气层敏感的弹性参数——密度。利用叠前时间偏移的CRP道集数据、速度数据和井数据,通过叠前弹性反演得到了密度数据体。密度能够有效区分气层和水层,利用密度数据预测了气藏分布范围,共划分出5个气藏分布区。两口检验井和一口后钻井证实了预测结果的准确性。因此,叠前弹性反演是该区碳酸盐岩气藏预测的有效方法。

Conventional post-stack inversion and traditional AVO technique is hard to effectively predict the subsalt carbonate gas reservoir in block Y.aiming at the problem,we used pre-stack elastic parameter inversion to predict gas reservoir.By the crossplot analysis on different fluid elastic parameters (the lithology in the area is pure),density and elastics wave impedance were selected because of their sensitivity on carbonate gas layer.By using the CRP gather from pre-stack time migration,velocity and well data,the data volume of density and elastic wave impedance were achieved by pre-stack elastic inversion.In the target intervals (hp+a1),density can effectively distinguish gas and water layers.We applied density and elastic wave impedance data to predict the distribution of gas reservoir,five favorable gas areas was identified.Two checking wells and one well drilled later proved the accuracy of the prediction results;therefore,pre-stack elastic inversion is the effective method for predicting carbonate gas reservoir.