塔河油田蓬莱坝组异常地震特征及地质成因分析

Characteristics and geological genesis of anomalous seismic facies of Penglaiba Formation in Tahe Oilfield

为寻找塔河油田奥陶系蓬莱坝组优质白云岩储层,利用三维地震资料与正演模拟开展了异常地震特征识别,并进行了地质成因分析。结果表明:(1)蓬莱坝组异常地震特征表现为多层、短连续的强反射,外部形态为块状或层状,分布于断裂单侧或双侧,纵向受层位约束,多终止于蓬莱坝组顶部不整合面之下;(2)强反射地震相总体上发育于构造主体部位,平面上呈3个有利区带,其中在塔河油田中北部与西北部均较发育,展布方向与深大断裂一致,呈NE与NNW向;(3)强反射地震相的主要成因机制为断裂-热液作用,其宏观上受控于构造格局,发育于构造高部位,深大断裂是热液流体的主要运移通道,向上终止于上覆的致密盖层。因此,蓬莱坝组优质白云岩储层为热液成因,强反射特征为该套优质白云岩储层在地震上的重要识别标志。

In order to find high-quality dolomite reservoirs of the Ordovician Penglaiba Formation in Tahe Oilfield,three-dimensional seismic data and forward modeling were used to identify the anomalous seismic features,and geological genesis analysis was carried out.The results show that:(1)the anomalous seismic facies of Penglaiba Formation are characterized by multi-layered,short-continuous strong reflection,massive or layered external forms,distributed on one or both sides of faults,longitudinally constrained by horizon,and mostly terminated under the unconformity surface at the top of Penglaiba Formation.(2)The strong reflection seismic facies generally developed in the main part of the structure,and there are three favorable zones on the plane,which are relatively developed in the north-central and northwestern Tahe Oilfield.The distribution direction is consistent with deepfaults,showing NE and NNW directions.(3)Fault-hydrothermal process is the main genetic mechanism of the strong reflection seismic facies which is macroscopically controlled by tectonic framework and developed in the high part of structure.The deep faults are the main transport channels of hydrothermal fluids and terminate upwards in the overlying tight caprock.Therefore,high-quality dolomite reservoirs developed in Penglaiba Formation are of hydrothermal genesis,and the strong seismic reflection is an important seismic identification mark for high-quality dolomite reservoirs.