叠前地震反演在清水地区砂砾岩优质储层预测中的应用

APPLICATION OF PRE-STACK SEISMIC INVERSION TO PREDICTION OF HIGH-QUALITY GLUTENITE RESERVOIRS IN QINGSHUI DISTRICT

辽河坳陷清水地区沙一段广泛发育了扇三角洲砂砾岩沉积,与同期沉积的暗色泥岩形成了良好的生储盖组合,是寻找岩性油气藏的有利地区。沙一段主要储层为含砾砂岩、细砂岩,受含灰质成分影响,含灰泥岩、含灰粉砂岩等非储层与储层的波阻抗相互重叠,利用常规叠后波阻抗反演无法准确预测优质储层。基于岩石物理分析,指出λρ和μρ为识别优质储层的敏感弹性参数。在叠前道集优化处理和横波预测的基础上,通过叠前地震反演得到λρ和μρ,对扇三角洲砂砾岩优质储层的分布特征进行了预测,为清水地区砂砾岩岩性油气藏勘探提供了依据。

In the Qingshui district of the Liaohe Depression,the 1st Member of the Shahejie Formation was widely deposited as a fan-delta glutenite.The glutenite,together with syn-deposited dark shale,forms good source-reservoir-cap systems for lithologic reservoirs.The main reservoirs of the 1st Member of the Shahejie Formation are made up by pebbly fine sandstone.However,due to the existence of carbonate cement,wave impedance of non-reservoirs,such as limy shale and limy siltstone,is hard to be distinguished from that of the reservoirs.That is to say,high-quality reservoirs can not be predicted precisely by conventional stacked impedance inversion.Petrophysical analysis suggests thatλρandμρare good elastic parameters for recognition of high-quality reservoirs.Based on the optimizing process of pre-stack gathers and transverse wave prediction,λρandμρhave been obtained by prestack seismic inversion and used to predict the distribution pattern of high-quality fan-delta glutenite reservoirs to promote exploration in the glutenite lithologic reservoir in the Qingshui district.