Late Triassic fracture detection with seismic azimuth anisotropics in Huang 257 survey, Ordos Basin
Li Huiqiong1, Zhang Mengbo2, Pu Renhai1, Zhang Jie2, Ding Guodong3
1. Department of Geology, Northwest University, Xi'an, Shaanxi 710069, China;
2. Research Institute of Exploration and Development, Changqing Oilfield Company Ltd., PetroChina, Xi'an, Shaanxi 710021, China;
3. Research Institute of Geophysics, SINOPEC, Nanjing, Jiangsu 211103, China
Abstract：Yanchang formation in the Huang 257 area,Ordos Basin is deeply buried and tightly compacted sandstones and its natural fractures play a definite role in improving reservoir property.In order to research fracture characteristics and its effects on reservoirs,prestack impedance of P-wave anisotropic are utilized to predict fracture density and direction on 60km2 3D seismic data.The following observations are obtained:A.Fracture direction predicted by prestack impedance is consistent with that predicted by poststack coherence and dip,The fracture direction is mainly NWW spreading in Chang 6 Mem and Chang 71 Mem,but N-S spreading in Chang 72,Chang 73,Chang 8,and Chang 9 Mem.The fracture direction is parallel or perpendicular to the fault direction,and might be resulted in by different stress fields in Yanshan and Himalayan periods or local plastic deformations of Chang 72 and Chang 73 shale; B.The fracture density in the area is low.According to logging data,fracture density in the area was controlled by sand body thickness and oil content.It is more obvious in 100m thick strata than 30m thick strata.Well oil test data show that sand body oil-bearing property is affected by reservoir thickness and fracture density in developed fracture area.Our practice shows that strata unit thickness to be predicted with the proposed approach should not be too thin due to the limited seismic resolution.If target thickness is more than 1/2 wavelength (60m),prediction is reliable.
Zhang Li. Characteristics of reservoir fracture and the analysis of stress field in Shaanxi-Gansu-Ningxia basin.Geological Science and Technology Information,2003,22(2):21-24.
Liu Baoxian,Zhang Jun,Zhang Guisong et al. Characteristics of fracture systems in Ordovician in central east Ordos basin. Natural Gas Industry,2002,22(6):35-38.
Zhang Yikai,Zhou Lifa,Dang Ben et al. Characteristics of distribution of the field outcrop fracture systems in Triassic and Jurassic in Central-east Ordos Basin. Geotectonica et Metallogenia,2006,30(2):168-173.
Bi Yanbin,Long Shengxiang,Guo Tonglou et al. Application of seismic azimuth anisotropic technique in fractural detection of Lower Triassic Jia-2 reservoir in TNB area. OGP,2009,44(2):190-195.
[6]
Tsvankin I. Reflection moveout and parameter estimation for horizontal transverse isotropy. Geophy-sics,1987,62(2):614-629.
[7]
Ruger A. Using AVO for fracture detection:analytic basis and practical solutions. The Leading Edge,1997,16(10):1429-1430,1432-1434.
[8]
Perez M A,Grechka V,Michelena R J. Fracture detection in a carbonate reservoir using a variety of seismic methods.Geophysics,1999,64(4):1266-1276.
Qu Shouli,Ji Yuxin,Wang Xin et al. Seismic method for using full azimuth P wave attribution to detect fracture. OGP,2001,36(4):390-397.
[10]
Shen F,Sierra J,Burns D R et al. Azimuthal offset-dependent attributes applied to fracture detection in a carbonate reservoir.Geophysics,2002,67(2):355-364.
Li Zhong,Liang bo,Wu Furong et al. Application of intergrated seismic fracture detection technology in tight sand reservoirs in the western Sichuan Basin. Natural Gas Industry,2007,27(2):40-42.
Wang Hongqiu,Yang Wuyang,Xie Chunhui et al. Azimuthal anisotropy analysis of different seismic attributes and fracture prediction.OGP,2014,49(5):925-931.
Liu Limin,Chen Xifeng,Fu Bo et al. Application of seismic P-wave azimuth anisotropic technique for fracture detection in Huawa area. Complex Hydrocarbon Reservoirs,2014,7(3):36-41.
Wang Qiyu,Zheng Rongcai,Liang Xiaowei et al. Feature and genesis of the reservoir fractures of Upper Triassic Yanchang Formation in Jiyuan area,Ordos Basin. Journal of Chengdu University of Technology(Science & Technology Edition),2011,38(2):221-228.
Yang Hua,Tao Jiaqing,Ouyang Zhengjian et al. Structural characteristics and forming mechanism in the western margin of the Ordos Basin. Journal of Northwest University of Technology(Science & Technology Edition),2011,41(5):863-868.
Deng Hucheng,Zhou Wen,Jiang Wenli et al. Genetic mechanism and development periods of fracture in Yanchang and Yan'an formation of western Mahuang-shan Block in Ordos Basin. Journal of Jilin University(Earth Science Edition),2009,39(5):811-817.
Tang Xiaomei,Zeng Lianbo. Effect of deposition and diagenesis on Tectonic fractures of sandstone reservoirs with ultra-low permeability in Jiyuan Oilfield. Oil and Gas Technology,2012,34(4):21-35.
Zeng Lianbo,Qi Jiafu,Wang Yongxiu. The origin type of tectonic fractures and its geological formation conditions in low-permeability reservoirs. Acta Petrol Sinica,2007,28(4):52-56.
Zeng Lianbo,Qi Jiafu,Wang Chenggang et al. The influence of tectonic stress on fracture formation and fluid flow. Earth Science Frontiers,2008,15(3):292-298.
Niu Xiaobing,Hou Guiting,Zhang Juzeng et al. Assessment criteria for Member 6 and 7 tight sand in Ordos Basin and its applications. Geotectonica et Metallogenia,2014,38(3):571-579.
