基于高精度构造解释的滩相白云岩储层预测——以四川盆地龙女寺—合川地区茅口组为例

Prediction of shoal facies dolomite reservoirs based on structural interpretation with high precision:An example from Maokou Formation,Longnvsi-Hechuan area,Sichuan Basin

四川盆地龙女寺—合川地区中二叠统茅口组气藏获得重大勘探发现,是近期实现万亿立方米规模突破的最佳领域。该区中二叠统茅口组以台内滩相白云岩储层为主,沿古隆起边缘发育,规模、潜力较大,但该气藏埋藏深、受不同程度岩溶作用影响导致储层空间分布复杂、物性差,表现为内部小层难以精细解释、储层地震响应特征不清、储层预测难度大等难点。为支撑该区茅口组勘探开发需求,以白云岩储层预测为导向,结合精细描述白云岩储层主要参数为目标,采用“高精度构造解释+微古地貌刻画”技术,基于茅口组内部小层精细解释开展茅口组古地貌、有利相带预测研究,最后利用相控白云岩储层反演技术开展储层空间展布研究,解决茅口组台内滩发育有利区精细刻画难题。研究结果表明,基于相控的白云岩薄储层预测技术能够更好地反映储层空间分布,为成功预测白云岩储层发育带打下基础,有效支撑了勘探开发井位部署并取得丰硕成果,为下一步川中地区井位部署提供有力支撑。

Gas reservoirs of the Middle Permian Maokou Formation,Longnvsi-Hechuan area,Sichuan Basin,have achieved signifi-cant exploration discoveries,making them the best domain for the future breakthrough across trillions of cubic meters.There majorly developed dolomite reservoirs of intra-platform shoal facies in this formation,which extend along the edge of paleo-uplift with large-scale resources and great exploration prospects.However,Maokou reservoirs exhibit complex spatial distribution and poor physi-cal properties due to deep burial depth and various karstification,resulting in difficult fine interpretation of interlayers,ambiguous seismic-response characteristics,and challenges in reservoir prediction.For purpose of reservoir prediction and description on key parameters to support the exploration and development in this area,both ancient landform and favorable facies of the Maokou Forma-tion were predicted by using the technology of“structural interpretation with high precision and ancient-landform characterization”and based on interlayer interpretation.Additionally,through inversion of facies-controlled dolomite reservoirs,the spatial distribution of reservoirs was determined to facilitate the delineation of favorable intra-platform shoal zones in this Maokou Formation.Results show that the technology of facies-controlled thin dolomite reservoir prediction may effectively reflect the spatial distribution,laying a foundation for predicting the dolomite reservoirs to support well deployment and exploration and development practices in central Sichuan Basin.