基于数值和物理模拟的低幅度构造成像

Low-amplitude structural imaging based on seismic numerical simulation and physical modeling

勘探实践证明,低幅度构造在有利的生储盖和油气运移条件下可形成"小而肥"的高产油气藏,冀东马头营地区低幅度构造成像精度低,与钻井存在较大误差。主要原因在于传统速度建模技术不能很好地解决浅层不同砂地比引起的横向变速问题。为此,提出了基于地震模拟的低幅度构造速度建模技术,设计能够突出该区主要矛盾的简化模型,并开展物理模拟、数值模拟。地震模拟可以通过真实速度偏移得到正确的成像结果,同时将真实速度、地层形态作为先验信息,开展低幅度构造速度建模研究,检验技术的有效性。研究结果表明沿层层析反演技术可以计算出精度相对较高的初始速度模型,高密度构造约束网格层析成像技术可以构建出高精度的符合速度变化规律的模型。两项速度建模技术联合应用提高了低幅度构造的成像精度。

Exploration cases show that low-amplitude structures can form small but high-yield reservoirs with favorable conditions of source-reservoir-cap and oil-gas migration.However,traditional methods of velocity modeling cannot eliminate lateral variation of velocity usually caused by the varying proportion of sand in shallow formations and produce a velocity model with low precision,giving rise to poor imaging precision of low-amplitude structures in Matouying area in Jidong oilfield with big drilling deviation.In this paper,the velocity modeling technology for low-amplitude structural imaging based on seismic numerical simulation and physical modeling is proposed.A simplified model that highlights the major characteristic in this area is designed for seismic numerical simulation and physical modeling.Seismic simulation experiments show that correct imaging results can be obtained with the real velocity.At the same time,real velocity and stratigraphic form are used as the prior information for velocity modeling of low-amplitude structures to validate the technology.The results show that the tomographic inversion along the formation can create a precise initial velocity model,and the high-density structure-constrained grid tomographic imaging technology can build a highly precise model that indicates the trend in velocity.Therefore,the joint application of two modeling technologies leads to more precise imaging of lowamplitude structures.