致密砂岩油气藏地震正演模拟  

Seismic forward modeling of tight sandstone reservoir

作　　者：张雨 许胜利 但玲玲 ZHANG Yu;XU Shengli;DAN Lingling(CNOOC EnterTech-Drilling&Production Co.,Tianjin 300459,China)

机构地区：[1]中海油能源发展股份有限公司工程技术分公司,天津300459

出　　处：《非常规油气》2024年第1期29-35,共7页Unconventional Oil & Gas

摘　　要：地震正演是地震储层预测必不可少的部分。在致密砂岩储层中,正演研究相对较少,反射特征认识不充分,而目前随着勘探开发进入隐蔽化,需要加强对致密砂岩储层发育特征的认识。为提高这一认识,以H油田C8油组为例开展了致密储层的正演研究,取得了以下研究成果:1)砂厚与地震属性之间的关系受砂泥岩阻抗差大小的影响。当阻抗差较大时,振幅随厚度的变化幅度明显;当阻抗差依次减小时,振幅随砂厚变化的幅度也依次变小。2)存在着一个临界的孔隙度0.08,当孔隙度小于0.08时,砂岩对应波峰-波谷,振幅随孔隙度增大而减小;当孔隙度等于0.08时,砂泥岩阻抗相等振幅为零;当孔隙度大于0.08时,极性出现反转,砂岩对应波谷-波峰,振幅随孔隙度增大而增大。3)河道的正演结果表现为单个复合河道地震同向轴相应为顶平底凸的下切和边部收敛;两河道纵向切叠为晚期河道切割出现下切和边部收敛;河道侧向切叠为早期复合河道被晚期的河道切割,晚期复合河道形态保存完整。4)前积体的正演结果表现为明显的顶底板反射及两侧反射形成平行四边形的形状。利用该研究成果对C8油组进行了储层砂体的预测,共识别河道7条,为进一步的储层预测奠定了基础。Seismic forward modeling is an essential part of seismic reservoir prediction.There are relatively few forward modeling studies for tight sandstone reservoirs and insufficient understanding of reflection characteristics.With the concealment of exploration and development,it is necessary to strengthen the understanding of the development characteristics of tight sandstone reservoirs.In response to this problem,this paper takes C8 oil formation of H oilfield as an example to carry out the forward modeling research of tight reservoir,and the following results are obtained:1)The relationship between sandstone thickness and seismic attributes is affected by the impedance difference between sand sandstone and mudstone.The amplitude obviously changes with the thickness when the impedance difference is large,and the amplitude variation with sand thickness decreases when the impedance difference decreases.2)There is a critical porosity of 0.08 when the porosity is less than 0.08,the sandstone corresponds to wave crest and wave trough,and the amplitude decreases with the increase of porosity;the impedance of sand and mudstone is equal,and the amplitude is zero when the porosity is equal to 0.08;the polarity reverses when the porosity is greater than 0.08,the sandstone corresponds to the trough peak,and the amplitude increases with the increase of porosity.3)The seismic phase axises of the forward modeling results of the river channels show that a single composite river channel is characterized by undercutting with flat top and convex bottom and edge convergence;the longitudinal cutting and overlapping of the two river channels is characterized by undercutting and edge convergence in late river cutting;the lateral cutting and overlapping of the river channels shows that the early composite river channel is cut by the late river channel,and the late composite river channel is completely preserved.4)The forward modeling results of the prograding complex show that the top and bottom plate reflections and the reflections on bot

关 键 词：致密砂岩 正演模拟 储层预测 河道追踪 复合河道 

分 类 号：P631.4[天文地球—地质矿产勘探]