油气检测多技术联合在B油田的应用研究

B油气田处于开发初期,钻井少,目标区内含气储层边界认识不清,直接影响油田储量准确计算及后期开发井网部署和优化。为准确落实油田含气储层边界,利用分频能量衰减技术、AVO分析技术以及叠前弹性参数反演等多技术结合,并与已钻井相互印证,开展目标区含气储层地震响应特征分析,进而准确预测目标区含气储层边界。分析表明,受地震波衰减特性的影响,目标区含气储层具有低频能量增加、高频能量减弱的“低频共振、高频衰减特征;通过已钻井AVO正演分析可以判定目标区含气储层属于第Ⅲ类AVO异常,其地震正振幅随偏移距的增大而增强;岩石物理参数中,拉梅系数、泊松比、纵横波速度比为含气砂岩敏感参数,且泊松比区分含气砂岩的效果最好,可较好地反映含气储层平面分布。分频能量衰减、AVO分析及叠前弹性参数反演能较好地检测含气储层,多技术结合相互印证有助于提高含气储层边界预测精度,为目标区储量准确计算和开发井网部署优化提供支持。

The application of multi-seismic hydrocarbon detection technology to gas identification in B oilfield

The target field is in the early stage of development with few drilling wells.Unclear boundary of gas reservoir in the target area affects accurate calculation of oil field reserves and well pattern deployment for later development.To solve this problem,the authors analyzed the seismic response characteristics of gas-bearing reservoirs in the target area by spectral decomposition energy attenuation,AVO analysis and pre-stack elastic parameter inversion technology,and then predicted the boundary of gas-bearing reservoirs in the target area.The result shows that the gas-bearing reservoir in the target area is characterized by "low frequency resonant and high frequency attenuated".That means the increase of low frequency energy and the decrease of high frequency energy due to the attenuation of seismic wave.Through AVO forward analysis of drilled well,it can be determined that the gas-bearing reservoir in the target area belongs to class III AVO anomaly,and its seismic positive amplitude increases with the increase of offset distance.Among the petrophysical parameters,Lame's coefficient,Poisson's ratio and P-S wave velocity ratio are sensitive to gas-bearing sandstone.Besides,Poisson's ratio is the best one for distinguishing gas-bearing sandstone and can reveal the gas-bearing reservoir and predict its plane distribution.Applying spectral decomposition energy attenuation,AVO analysis and pre-stack elastic parameter inversion technology,the authors detected gas-bearing reservoirs. With the application of multi-technology,the prediction precision of gas-bearing reservoir boundary can be improved and this would provide support for accurate calculation of reserves and development of well pattern deployment in the target area.