基于声学全波形反演的油气藏地震成像方法

Methodology of seismic imaging for hydrocarbon reservoirs based on acoustic full waveform inversion

岩性油气藏在我国天然气勘探开发中占有非常重要的位置,其分布区域的成像是合理布设井位,提高钻井成功率的关键之一.本文首先基于地下介质的声学近似和波场回传理论,利用频率域单程声波方程延拓计算地震波场,进行全波形反演,获得地层密度和体积模量的定量成像,并依据油气藏物性特征和流体饱和多孔介质岩石物理模型,简要讨论了孔隙度和饱和度与密度及体积模量的关系,明确了地震油气藏成像新概念.在此基础上,定义了基于流体体积模量和孔隙度的成像函数,进行油气藏成像.理论模型计算表明该方法是可行的.通过对西部地区某气田二维地震数据处理,实现了致密砂岩气藏成像,钻井结果证实了气藏区域成像位置的准确性和方法的有效性.

The exploration and development of stratigraphic reservoirs is important in the oil and gas industry.Imaging these reservoirs is one of the keys for reasonable deployment of wells and enhancement of success rates of drilling.Based on the acoustic approximation,the inversion of mass density and bulk modulus are imaged using full waveform inversion and one-way wave field extrapolation in the frequency domain.According to the characteristics of reservoirs and rock physics models of saturated porous media,we briefly discuss the relationships between porosity and saturation with the inversion results,and then define the imaging function for the hydrocarbon reservoirs.The feasibility of the method has been tested by a synthetic example.We have applied this method to 2Dfield data from a tight gas sand field in western China to illustrate the accuracy of the gas reservoir imaging and the effectiveness of the method.