Influences of coal seam on seismic reflection characteristics of sand and significances of seismic lithology: a case study of Shan-2 member in Ordos Basin
Lai Shenghua1, Liang Quansheng2, Zeng Hongliu3, Li Pengfei1
1. Xi'an Shiyou University, Xi'an, Shaanxi 710065, China;
2. Yanchang Petroleum (Group) Co. Ltd., Xi'an, Shaanxi 716000, China;
3. University of Texas at Austin, Austin 78758, USA
Abstract:According to the fact that sand is directly overlain or underlain by coal seam of Permian Shan 2 member in Ordos Basin, six geologic models were designed, which include three layered sand models and there wedge-shaped sand models. The corresponding reflection coefficient of the models and Ricker wavelets with 0°and 90°phases and dominant frequencies from 5 to 120Hz (step 5Hz & sample interval 1ms) are calculated by convolution model, and then synthesis seismic datasets with different frequencies were obtained. Coal seam influence on seismic reflection characteristics of sand under wavelets with 0°and 90° phases were firstly simulated by extracting synthetic seismogram of upper, lower, and medium sand amplitude. The results show that coal seam thickness, position and the distance between coal and sand have influence on tuning frequency, tuning amplitude, reflection strength and polarity of seismic reflection. Coal seam can reverse polarity of sand seismic reflection, so sandstone thickness prediction is very difficult. When both coal seam thickness and the distance between coal and sand vary, the upper, lower, and medium sandstone amplitude cannot indicate its thickness. When thickness and position of coal seam vary, other methods should be used, such as amplitude slice at different positions.
赖生华, 梁全胜, 曾洪流, 李鹏飞. 煤层对砂岩地震反射特征的影响及其地震岩性学意义—以鄂尔多斯盆地山2段为例[J]. 石油地球物理勘探, 2015, 50(1): 136-143.
Lai Shenghua, Liang Quansheng, Zeng Hongliu, Li Pengfei. Influences of coal seam on seismic reflection characteristics of sand and significances of seismic lithology: a case study of Shan-2 member in Ordos Basin. OGP, 2015, 50(1): 136-143.
Lai Shenghua,Li Xiaohong.A new approach in studying depositional system within rift-subsidence basin:from paleogeomorphology,lithologic change and water depth to depositional system.Acta Sedimentologica Sinica,2007,25(5):663-670.
Lai Shenghua,Pu Xiugang,Du Guirong.Characteristics of sedimentary facies response to the seismic wave—An example of the 3rd member of Shahejie formation in the Gunan sag of the Bohai bay basin.Petroleum Geology & Experiment,2008,30(4):400-405.
Li Lei,Wang Yingmin,Xu Qiang et al. 21 Ma deepwater gravity flow depositional system in Baiyun sag,northern South China Sea.Acta Petrolei Sinica,2012,33(5):798-806.
Huang Yaping,Shu Ronghua,Dong Shouhua et al.Application of wave impedance inversion technique to the seismic lithological exploration in coalfield.Coal Geology & Exploration, 2008,36(5):62-64.
Jia Jianliang,Liu Zhaojun,Chen Yongcheng et al. Lithologic prediction and application of log-constrained seismic—an example from SD2 segment of Dalianhe formation in Tangyuan fault depression.Global Geology,2009,28(3):339-344.
[6]
王家映.地球物理反演问题概述.工程地球物理学报,2007,4(1):1-3.
Wang Jiaying.Introduction to geophysical inverse problems.Chinese Journal of Engineering Geophy-sics,2007,4(1):1-3.
Zhang Shaohong.Application of probabilistic neural network technique to lithology inversion of heterogeneous stratum.Acta Petrolei Sinica,2008,29(4):549-552.
[8]
Widess M B. How thin is a thin bed?Geophysics,1973,38(6):1176-1180.
Huang Wenfeng,Yao Fengchang and Li Hongbin.Regularities of tuning effects of thin interbedded layers and their net thickness determination.OGP,2012,47(4):584-591.
Li Guofa,Yue Ying,Guo Chunxiang et al.Seismic attributes analysis based on model in interbedded layers and its application.GPP,2011,50(2):144-149.
[13]
Vail P R.Seismic Stratigraphy Interpretation Using Sequence Stratigraphy,Part 1:Seismic Stratigraphy Interpretation Procedure,in Bally A W ed.Atlas of Seismic,1987.
Zeng H,Backus M M,Barrow K T et al.Stratal slicing,Part Ⅰ:Realistic 3-D seismic model. Geophy-sics,1998,63(2):502-513.
[16]
Zeng H,Henry S C and Riola J P.Stratalslicing,PartⅡ:Real seismic data.Geophysics, 1998,63(2):514-522.
[17]
Zeng H and Kerans C.Seismic frequency control on carbonate seismic stratigraphy:A case study of the Kingdom Abo sequence,west Texas.AAPG Bulletin,2003,87(2):273-293.
[18]
Wood L C.Imaging the subsurface,in Jain K C and de Figueiredo R J P ed,Concepts and Techniques in Oil and Gas Exploration.SEG,1982,45-90.
Huang Junbin,Gao Lijun and Gao Yong et al.Wavelet effect and recognition methods of thin sand bodies in braided river facies.Oil & Gas Geology,2010,31(2):225-231.
Brown A R.Interpretation of three-dimensional seismic data(3rd ed).AAPG Memoir 42,1991.
[22]
Sengbush R L,Lawrence P L and McDonald F J.Interpretation of synthetic seismograms.Geophysics,1961,26(1):138-157.
[23]
Zeng H and Backus M M.Interpretive advantages of 90°-phase wavelets, Part Ⅰ: modeling.Geophysics,2005,70(3):C7-C15.
[24]
Zeng H L,Hentz T F and Wood L J.Stratal slicing of Miocene-Pliocene sediments in Vermilion Block 50-Tiger Shoal area,offshore Louisiana. The Leading Edge,2001,20(4): 408-418.
[25]
Zeng H and Hentz T F.High-frequency sequence stratigraphy from seismic sedimentology:Applied to Miocene, Vermilion Block 50,Tiger Shoal area,offshore Louisiana.AAPG Bulletin,2004,88(2):153-174.
[26]
Zeng H and Backus M M.Interpretive advantages of 90°-phase wavelets,Part Ⅱ:seismic applications.Geophysics,2005,70(3):C17-C24.
[27]
Zeng H,Backus M M,Barrow K T et al.Facies mapping from three-dimensional seismic data:potential and guidelines from a Tertiary sandstone-shale sequence model,Powderhorn Field,Calhoun County,Texas.AAPG Bulletin,1996,80(1):16-46.
[28]
Sicking C J.Windowing and estimation variance in deconvolution.Geophysics,1982,47(7): 1022-1034.