准噶尔盆地南缘复杂构造变速成图方法及效果分析
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摘要
准噶尔盆地南缘冲断带西段浅层发育有巨厚砾岩段,由于砾岩段在地震速度上没有能量团聚焦,不能反映砾岩段的真实地层速度,造成未准确落实砾岩影响的情况下速度成图精度较低;准南缘中东段有利目标多为高陡构造,地层逆掩严重,地层速度纵横向变化大,由于前期速度成图中无法实现考虑浅层逆掩地层的速度建模,造成深层目的层的变速成图精度较低。针对准南缘速度成图特点,应用标准层校正速度异常方法,消除了地震异常谱点影响,提升了地震速度品质;应用速度异常分析方法,基本搞清了深层速度异常的分布和影响;应用钻井地层速度变速充填方法,在考虑地层逆掩的情况下建立速度模型,形成较为合理的速度场。通过以上技术措施的应用,为准南缘冲断带的油气勘探提供了比较可靠的构造图,在该区的油气勘探中发挥了重要作用。
Thick conglomerate had developed in the shallow formation in the west part of the thrust belt on the south margin of Junggar Basin.The conglomerate segment shows no energy group on seismic velocity spectrum,the true formation velocity of the conglomerate segment can not be reflected,thereby resulted in low accuracy in velocity mapping.In the middle and east part of the south margin,favorable targets are mostly steep structures,overthrust structures are common,both lateral and vertical formation velocities change drastically,the previous velocity modeling did not represent the shallow overthrust structures,thus resulted in low accuracy in variable velocity mapping for deep target formations.Based on the characteristics of variable velocity mapping for the south margin of Junggar Basin,marker bed has been used to correct velocity anomaly,eliminate the effect of abnormal seismic spectral points,and improve the quality of seismic velocity.The distribution and impact of velocity anomaly in deep formations are basically understood by using velocity anomaly analysis method.A velocity model has been set up to establish a reasonable velocity field by using variable velocity filling with drilling formation velocity and considering overthrust structures.The application of the above technical measures has provided reliable structure maps for oil and gas exploration in the thrust belt of the south margin of Junggar Basin,and has played an important role in the exploration in this area.
Thick conglomerate had developed in the shallow formation in the west part of the thrust belt on the south margin of Junggar Basin.The conglomerate segment shows no energy group on seismic velocity spectrum,the true formation velocity of the conglomerate segment can not be reflected,thereby resulted in low accuracy in velocity mapping.In the middle and east part of the south margin,favorable targets are mostly steep structures,overthrust structures are common,both lateral and vertical formation velocities change drastically,the previous velocity modeling did not represent the shallow overthrust structures,thus resulted in low accuracy in variable velocity mapping for deep target formations.Based on the characteristics of variable velocity mapping for the south margin of Junggar Basin,marker bed has been used to correct velocity anomaly,eliminate the effect of abnormal seismic spectral points,and improve the quality of seismic velocity.The distribution and impact of velocity anomaly in deep formations are basically understood by using velocity anomaly analysis method.A velocity model has been set up to establish a reasonable velocity field by using variable velocity filling with drilling formation velocity and considering overthrust structures.The application of the above technical measures has provided reliable structure maps for oil and gas exploration in the thrust belt of the south margin of Junggar Basin,and has played an important role in the exploration in this area.
引文
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[2]冯许魁,等.复杂高陡构造区变速成图技术[J].石油地球物理勘探,2002,37(专刊):172-175.
[3]杨长春,冷传波,李幼铭.适用于复杂地质模型的三维射线追踪方法[J].地球物理学报,1997,40(3):414-420.
[4]刘爱群,童传新,李林.莺东斜坡带速度分析方法研究及速度影响因素分析[J].地球物理学进展,2008,23(6):1909-1917.
[5]罗涛,刘传川.构造复杂区变速成图方法探讨[J].江汉石油学院学报,2004,26(4):80-81.
[6]王西文,等.多井约束下的速度建模方法和应用[J].石油地球物理勘探,2003,38(3):263-267.
[7]邵雨,李学义,孔志勇,等.模型速度建场方法的研究[J].石油地球物理勘探,2003,38(6):675-679.
[8]蔡刚,屈志毅.构造复杂地区地震资料速度和成图方法研究与应用[J].天然气地球科学,2005,16(2):246-249.
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