岩石物理分析在番禺天然气区含气性研究中的应用

Application of petrophysical analysis for gas-bearing prediction of Panyu Gasfield

番禺天然气区P目标主要目的层段是一个构造-岩性复合圈闭,使用常规的地震振幅亮点技术以及传统的AVO分析方法在预测储层物性和流体性质时失效。为了准确预测储层物性和流体性质,首先对研究区测井曲线进行初始校正,得到较准确的储层特征参数;然后基于岩石物理模型,根据Gassmann理论和Xu-White模型,通过测井曲线重构得到地下岩石在原始条件下的v_P,v_S和ρ。实际交会分析结果表明,经测井曲线重构得到的测井响应对储层物性和流体性质敏感,特别是v_P/v_S在区分气、水层方面效果明显。在此基础上开展了叠前弹性反演研究,反演结果清晰显示出A井和B井在目的层段因流体性质不同而产生的v_P/v_S差异。随后钻探的C井验证了反演结果,进一步证实了该方法在研究区储层反演和流体预测方面的有效性。

The main target of P object in Panyu Gasfield is a structure-lithology trap.Traditional seismic bright-spot and AVO analysis cannot effectively predict reservoir physical properties and fluid properties. Therefore,the log of the area was preliminary corrected to obtain relatively accurate reservoir characteristics parameters. Then,based on petrophysical model,combing with Gassmann theory and Xu-White model,the v_P,v_S andρin original formation condition were achieved by log reconstruction.Actual cross analysis indicates that the log response after log reconstruction is sensitive to reservoir physical properties and fluid properties,especially v_P/v_S is good at distinguishing gas and water layer.On this basis,pre-stack elastic inversion was carried out.The inversion result clearly displays the difference of v_P/v_S caused by different fluid properties in target formation of well A and well B.The well C deployed by the above research result also is accord with inversion result,which further proves the effectiveness of the method.