相控约束下的超深薄层砂体预测技术在塔北隆起玉东区块中的应用

Application of ultra-deep sandstone reservoirs prediction technology under seismic facies controlled in Yudong Block of Tabei Uplift,Tarim Basin

塔北隆起西部玉东地区白垩系巴西改组广泛发育薄层砂岩,形成受构造控制的岩性圈闭。储层厚度约3~5 m,而常规地震资料分辨率有限,储层预测难度大。从正演模拟出发,结合实钻井资料,设计不同的正演模型,分析了不同薄储层发育模式对地震波形的影响,实验结果表明:厚层块状砂岩发育时,振幅最强,而薄砂层发育时,振幅相对减弱;块状砂岩内部泥岩隔层发育时,振幅降低的同时波谷变宽。通过波谷宽度与振幅2种属性聚类交会,参考已钻井岩相信息,形成地震相平面图,平面上实现储层的定性预测;在此基础上开展相控约束下的高分辨率地震波形指示反演,明确含油砂体分布范围。实钻结果证实储层预测吻合率较高,纵横向上符合地质认识,从而明确了玉东地区白垩系巴西改组千万吨级油气勘探潜力,取得了较好的应用效果,对后期薄砂层油气藏勘探与开发具有重要的指导作用。

Thin sand layers are widely developed in the Cretaceous Baxigai Formation in Yudong area,western Tabei Uplift,and series of lithologic traps controlled by structures are formed. The thickness of target layer is 3-5 m,which is beyond the resolution of conventional seismic data,and the prediction of reservoir becomes difficult. Starting from the forward simulation,a forward model was designed based on well logging data and characteristics of the strata in the well area to analyze the impact of different thin reservoir development modes on seismic waveform. The experimental results show that the amplitude of thick sandstone is strong,while that of thin sandstone is weaker. When mudstone barriers developed in sandstones,the amplitude decreases and the trough widens. Based on results above,the seismic facies plan is formed by clustering the two attributes of wave trough width and amplitude,and the qualitative prediction of reservoir can be realized on the plane by referring to the drilled rock information. Based on this,high-resolution seismic waveform inversion was carried out to achieve vertical reservoir prediction. The results of inversion results on the profile are higher than those of well logging,and the geological knowledge is met on the plane and good application results are obtained.