相控叠前地质统计学反演在剩余油预测中的应用

Application of facies⁃controlled pre⁃stack geostatistical inversion in residual oil prediction

在老油田开发中后期,精准描述剩余油分布成为亟待解决的难题。叠前地震资料包含不同入射角的道集信息,通过分析振幅随入射角的变化特征可预测储层岩性和流体分布规律。为此,以大庆长垣BSX区块为例,在含流体岩石物理特征分析基础上,开展相控叠前地质统计学反演预测剩余油分布特征,以寻找潜力部位,实施精准挖潜。首先,明确随注水开发、含水饱合度逐渐增大引起的纵、横波响应特征,建立纵横波速度比、纵波阻抗的弹性流体岩石物理定量解释图板;其次,以纵横波速度比、纵波阻抗与含水(油)饱和度之间的关系为纽带,采用相控蒙特卡洛反演算法,生成高分辨率的岩石弹性参数体、含油饱和度体。应用结果表明,剩余油的分布预测结果与取心井岩心实测数据符合率达76.5%。该方法指导了BSX区5种剩余油的挖潜对策,可为其他陆相油田的高效开发提供借鉴。

In the middle and later stages of old oilfield development,how to accurately describe the remaining oil distribution has become an urgent problem to be solved.Pre⁃stack seismic data contain seismic gather information at different incidence angles.By analyzing the variation characteristics of amplitude intensity with incidence angles,reservoir lithology and fluid distribution laws can be predicted.Therefore,taking a BSX block of Daqing Placanticline as an example,based on the analysis of fluid and rock physical characteristics,this paper conducts facies⁃controlled pre⁃stack geostatistical inversion to predict the distribution characteristics of remaining oil to find potential areas and implement precise tapping.Firstly,the longitudinal and transverse wave response characteristics caused by the gradually increasing water saturation during water injection development are clarified,and a quantitative interpretation chart for elastic fluid rock physics with longitudinal and transverse wave velocity ratio and longitudinal wave impedance is established.Secondly,with the relationship between P⁃S wave velocity ratio,P⁃wave impedance,and water(oil)saturation as the link,a facies⁃controlled Monte Carlo inversion algorithm is adopted to generate highresolution rock elastic parameter volume and oil saturation volume.The application results show that the predicted remaining oil distribution has a coincidence rate of 76.5%with the measured data of core wells.This method guides the potential tapping strategies for five remaining oil types in the BSX area and can provide references for the efficient development of other terrestrial oilfields.