基于迭代岩相模型的叠前弹性参数反演在LB油田古近系陆相储层预测中的应用

Application of elastic inversion based on an iterative lithofacies model in predicting Paleogene terrestrial reservoirs in LB oilfield

中海石油(中国)有限公司深圳分公司,广东深圳518054

Shenzhen Branch,CNOOC(China) Limited,Shenzhen 518054,China

针对LB油田古近系地层D、E层组储层横向变化快、非均质性强、预测难度大等问题,提出了基于迭代岩相模型的叠前弹性参数反演方法。首先根据先验地质认识、测井曲线及岩石物理分析结果,确定了研究区的岩性并划分岩相;其次在常规低频模型的基础上,建立了考虑岩相约束的低频模型;然后构建模型约束反演方程并采用最小二乘方法求解弹性参数,再结合贝叶斯理论将弹性参数转换为物性参数;最后利用物性参数预测结果更新低频模型,并重复以上反演过程,最终得到高分辨率弹性参数反演结果。该方法在LB油田的实际应用结果表明,叠前弹性参数反演较传统反演方法分辨率更高,且与测井曲线吻合程度较好,证明了方法的有效性和实用性。与传统方法相比,该反演方法以地震数据为驱动,在少井或无井、储层横向变化快的储层预测中更有优势。

To accurately predict Paleogene reservoirs in LB oilfield with rapid lateral changes and strong heterogeneity,this paper proposes a prestack elastic parameter inversion method based on an iterative lithofacies model.Based on prior geological knowledge,log curves,and rock physics,we perform lithology definition and lithofacies classification.Based on the conventional low-frequency model,a lithofacies-constrained low-frequency model is established.The model-constrained inversion equations are formulated and solved using the least squares method to obtain elastic parameters,which will then be converted into petrophysical parameters using the Bayesian theory.The low-frequency model is updated using predicted petrophysical parameters,followed by the iterative inversion process to obtain high-resolution elastic parameters.The practical application in LB oilfield shows high resolution and credibility of the method proposed in this paper.Compared with traditional methods,this inversion method is driven by seismic data and has advantages in predicting reservoirs with fast lateral changes in an area with few or no well data.

“十三五”中海石油(中国)有限公司重大科技攻关项目(CNOOC-KJ135ZDXM37SZ)资助。

10.12431/issn.1000-1441.2025.64.01.009