摘要
地震勘探中“高速或低速致密砂岩储层”地震响应复杂、非均质性强、反演中的低频模型难以建立。在基于Bayesian分类的AVO(BF-AVO)截距、梯度属性及孔隙度等指标约束下,对川中地区侏罗系沙溪庙组致密砂岩的岩相进行了划分。研究结果表明:(1)AVO分析是以弹性波理论为基础,根据其振幅随偏移距的变化规律来反映地下岩性及其孔隙流体的性质,在应用过程中,根据不同岩性和流体的相关参数组合进行AVO正演,获得已知岩性和流体性质的AVO特征,与实际地震记录进行对比,建立岩性和油气识别的地震响应模型。(2)利用模型和实际数据建立的孔隙度与截距、梯度属性的交会分析,厘清三者的内在联系,确定岩相划分标准,并拟合出不同岩相的概率密度函数,划分出不同孔隙度区间的岩相,从而实现孔隙度的半定量预测。(3)川中侏罗系沙溪庙组沙一段致密砂岩的岩相预测过程中,基于Bayesian分类,以概率分布预测的岩相与实钻结果吻合度高,达93.75%,验证了该方法的可行性和有效性。
In seismic exploration,high-velocity or low-velocity tight sandstone reservoirs are often characterized by complex seismic response and strong heterogeneity,and it is difficult to establish a low-frequency model in inversion.With the constraints of AVO intercept and gradient attribute based on Bayesian classification and porosity,the lithofacies of the tight sandstone of Jurassic Shaximiao Formation in central Sichuan Basin was classified.The results show that:(1)Based on elastic wave theory,AVO analysis reflects the underground lithologies and pore fluid properties according to the variation of amplitude with offset.In the application process,AVO forward modeling was carried out based on the relevant parameter combination of different lithologies and fluids,AVO characteristics of known lithologies and fluid properties were obtained and compared with actual seismic records,and then a seismic response model for lithologies and oil and gas identification was established.(2)The crossplot analysis of porosity,intercept and gradient attributes established by model and actual data was used to clarify the internal relationship between the three,determine the classification criteria of lithofacies,fit the probability density function of different lithofacies,and divide the lithofacies of different porosity intervals,to realize the semi-quantitative prediction of porosity.(3)In the application of tight sandstone of the first member of Jurassic Shaximiao Formation in central Sichuan Basin,the lithofacies predicted by probability distribution based on Bayesian classification is up to 93.75%consistent with the actual drilling results,which verifies the feasibility and effectiveness of the method.
作者
陈康
戴隽成
魏玮
刘伟方
闫媛媛
郗诚
吕龑
杨广广
CHEN Kang;DAI Juncheng;WEI Wei;LIU Weifang;YAN Yuanyuan;XI Cheng;LYU Yan;YANG Guangguang(Research Institute of Exploration and Development,PetroChina Southwest Oil&Gas Field Compay,Chengdu 610041,China;GeoSoftware Techmology Services(Bejing)Co.,Ltd.,Bejing 00004,China)
出处
《岩性油气藏》
CAS
CSCD
北大核心
2024年第5期111-121,共11页
Lithologic Reservoirs
基金
中国石油西南油气田公司科技重大专项“四川盆地中西部地区致密气勘探开发理论及关键技术研究”(编号:2022ZD01-01)资助。
