济阳探区单一河道砂体边界地质建模及其地震正演响应特征分析

Geological modeling and seismic forward response characteristics analysis of single channel sand body boundary in Jiyang prospecting area

河道砂体边界识别是河流相岩性油气藏勘探与开发中的关键。由于河道砂体尺度小、散度大,地震资料的分辨率有限,砂体边界地震识别存在不确定性。在密井网条件下,应用钻井和测井等资料,从曲流河的沉积特点和演变规律出发,分析了河流相砂体边界的展布规律,研究了河道边界的接触关系,建立了典型模式,确定了单一河道边界的废弃河道沉积物、不连续河间砂体、河道砂体顶面层位差异和河道砂体厚度差异等4种识别标志,并分别建立了相应的地质模型。利用地震正演模拟技术研究了4种识别标志为边界条件的砂体地震响应特征,分析了反射振幅、频率、相位、波形和时间等变化规律,总结了在不同标志接触关系中应用水平切片、相干分析和地震属性等技术进行识别的可能性。将研究成果应用于济阳坳陷老168井区的河道砂体识别和精细描述,取得了较好的效果。

In the exploration and development of fluvial lithologic reservoir, the identification of channel sand body boundary is the key. Because of the small-scale and large scattered degree of the channel sand body and the limited resolution of seismic data,there is uncertainty in seismic recognition of sand body boundary.In dense well network condition,through the application of drilling and logging data,starting from the sedimentary characteristics and evolution of meandering river,we analyzed the distribution rules of fluvial sand body boundary,studied the contact relationship between the river boundaries,built their typical patterns,and identified the recognition signs of single channel boundary,including the sediments of abandoned channel,discontinuous interfluvial sand body,contrast of top layer and thickness difference of river sand body.The corresponding geologic models were separately established.Seismic forward modeling technology was used to analyze the seismic response characteristics of the sand bodies that take the four identification signs as boundary conditions.The changing rules of reflection amplitude, frequency,phase,wave form and time were analyzed,and the probability was discussed by using horizontal slice,coherent analysis and seismic attributes to recognize the sand body boundary with different identification signs.The achievements were used in Laol68 well area of Jiyang Depression for channel sand body identification and reservoir description,and good result was obtained.