地震三维三分量技术在致密砂岩裂缝预测中的应用——以川西新场气田为例
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摘要
川西坳陷陆相沉积领域深层须家河组气藏具有"四超二复杂",即超深、超致密和低孔渗、超晚期构造、超高压及复杂的气水关系、复杂的储层非均质性的特点,常规地震勘探技术预测和识别如此复杂的储层和裂缝系统面临重大挑战,特别是裂缝预测成为川西须家河组地震勘探面临的最大难题。转换波三维三分量地震勘探技术在获得能够反映岩石骨架及流体特性的常规 P 波资料的基础上,同时获得了反映骨架和各向异性特性的 C 波资料,在纵、横波联合区分岩性、流体性质以及利用转换波各向异性和横波分裂预测裂缝方面均比单纯的纵波勘探具有明显的优势。在川西新场气田须家河组气藏,通过转换波三维三分量地震资料的综合解释,充分利用三维三分量的纵波信息和转换波信息,开展 P 波地震属性裂缝预测、方位各向异性裂缝检测、横波分裂裂缝检测等多方面研究工作。在单纯利用 P 波地震属性预测大尺度断裂和裂缝发育带的基础上,利用速度方位各向异性和横波分裂预测了小尺度裂缝网络系统,提高了裂缝预测的精度,较好解决了新场气田须家河组超致密储层裂缝预测问题。
The reservoirs in the Xujiahe Formation in Western Sichuan Depression are characterized by ultra- deep burial,ultra-tightness,ultra-low porosity,ultra-low permeability,ultra-late structures,ultra-high pressure, complex GWC,and complex anisotropy.Therefore,conventional seismic techniques are faced with great challen- ges when predicting and identifying such complex reservoirs and fracture systems,especially the fractures in Xu- jiahe Formation in the Western Sichuan Depression.Both conventional P-wave data,which could reflect the cha- racteristics of matrix and fluid,and C-wave data,which could reflect matrix and anisotropy,could be achieved by using 3D-3C converted wave technique.This technique is of more advantages than simple P-wave technique in respect of identifying lithology and fluid property by using combined P-and S-wave data as well as predicting fractures by using azimuthal anisotropy of converted wave and split S-wave data.In view of the characteristics of the Xujiahe Formation gas reservoirs in Xinchang gas field,P-waves and converted waves 3D-3C data are fully utilized to perform fracture prediction with P-wave attributes,fracture detection with azimuthal anisotropy and fracture detection with split S-wave based on integrated interpretation of converted waves of 3D-3C data.Based on prediction of large-scale faults and fractured zones by only using P-wave attributes,small-scale fracture net- work is predicted by using azimuthal anisotropy and split S-waves.The problem of fracture prediction for the tight reservoirs in the Xujiahe Formation in Xinchang gas field is solved and the prediction accuracy is improved.
The reservoirs in the Xujiahe Formation in Western Sichuan Depression are characterized by ultra- deep burial,ultra-tightness,ultra-low porosity,ultra-low permeability,ultra-late structures,ultra-high pressure, complex GWC,and complex anisotropy.Therefore,conventional seismic techniques are faced with great challen- ges when predicting and identifying such complex reservoirs and fracture systems,especially the fractures in Xu- jiahe Formation in the Western Sichuan Depression.Both conventional P-wave data,which could reflect the cha- racteristics of matrix and fluid,and C-wave data,which could reflect matrix and anisotropy,could be achieved by using 3D-3C converted wave technique.This technique is of more advantages than simple P-wave technique in respect of identifying lithology and fluid property by using combined P-and S-wave data as well as predicting fractures by using azimuthal anisotropy of converted wave and split S-wave data.In view of the characteristics of the Xujiahe Formation gas reservoirs in Xinchang gas field,P-waves and converted waves 3D-3C data are fully utilized to perform fracture prediction with P-wave attributes,fracture detection with azimuthal anisotropy and fracture detection with split S-wave based on integrated interpretation of converted waves of 3D-3C data.Based on prediction of large-scale faults and fractured zones by only using P-wave attributes,small-scale fracture net- work is predicted by using azimuthal anisotropy and split S-waves.The problem of fracture prediction for the tight reservoirs in the Xujiahe Formation in Xinchang gas field is solved and the prediction accuracy is improved.
引文
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2 杨克明.川西坳陷须家河组天然气成藏模式探讨[J].石油与 天然气地质,2006,27(6) :786～793
3 叶军.川西坳陷天然气富集规律[A].见:杨克明,徐进,编.天然气成藏理论与勘探开发方法技术[C].北京:地质出版社,2004． 85～90
4 叶军,陈昭国.川西新场大型气田地质特征与预测关键技术[J].石油与天然气地质,2006,27(3) :384～391
5 张守仁,万天丰,陈建平.川西坳陷孝泉-新场地区须家河组二段-四段构造应力场模拟及裂缝发育带预测[J].石油与天然气地质,2004,25(1) :70～74
6 甘其刚,高志平.宽方位 AVA 裂缝检测技术应用研究[J].天然气工业,2005,25(5) :42～43
7 Corrigan D,Withers R,Damall J,et al.Fracture mapping from azimuthal velocity analysis using 3D surface seismic data[Z].66th Internat A & G,Sot Explor Geophys(Expanded Abstracts),1996． 1 834-1 837
8 Crampin S.A review of wave motion in anisotropic and cracked elastic medial J].Wave Motion,1981,3:343-391
9 Crampin S,Lovell J H.A decade of shear-wave splitting in the Earth's crust:what does it mean? What use can we make of it? And what should we do next?[J].Geophys J Internat,1991,107:387-407
10 Gaiser J E.3-D converted shear wave rotation with layer stripping[P].US:5 610 875,1997
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