频变AVO含气性识别技术研究与应用

Research and application of frequency dependent AVO analysis for gas recognition

在常规AVO理论的基础上,频变AVO属性计算方法利用多尺度裂缝介质模型中物性参数具有频变特征的优势,基于Zoeppritz方程建立反射系数与频率之间的数学关系,推导出截距、梯度、碳氢检测因子、流体检测因子、拟泊松比等AVO属性与频率之间的数学关系.应用地震反演方法,综合地质、地震、测井等数据,反演出高精度的频变AVO属性,在天然气敏感属性分析的基础上建立起频变AVO含气性识别技术.将该技术应用到川西新场陆相深层须家河组碎屑岩储层的含气性识别中,在孔隙度通常在1%～4%,渗透率普遍低于0.06×10-3μm2的致密背景下,较准确地预测了孔隙度大于4%、渗透性偏高的富气优质储层分布带,为该区含气性识别难题的解决和钻井成功率的提高,提供了重要的技术支撑.

Based on the theory of conventional AVO technology, the calculation method of frequency dependent AVO attributes takes advantage of physical parameters in multi-scale fracture media model which shows frequency dependent characters, establishes the mathematical relationship between reflection coefficient and frequency, derives the function of AVO attributes such as intercept, gradient, hydrocarbon factor, fluid factor, pseudo-Poisson ratio which are all related with frequency. Using the inversion method and geologic, seismic, and logging data, we obtained frequency dependent AV0 attributes with higher precision, developed frequency dependent AVO technology for gas recognition by analysis of gas sensitive attributes. A case study of this technology with seismic data from the deep formation in southwest China provides robust indications for reservoir prediction and gas detection, detected high quality gas reservoirzone with porosity greater than 4%from highly tight rock matrix where the porosity is generally 1-4% and the permeability is generally lower than 0. 06x 10.3 μm2. Practical application of frequency dependent AVO technology provides important technical support for solving the difficult problem of gas recognition and improving logging yield ratio.