川西坳陷中南段浅层气的地震响应特征
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摘要
近年来 ,四川盆地浅层天然气的勘探开发进入了新阶段 ,储量、产量迅速增长 ,在评价勘探中 ,精细的二、三维地震解释 ,在储层精细描述、储量计算、制订开发方案等方面起着重要作用。浅层天然气的勘探开发实践及地震资料的精细处理解释表明 ,浅层含气砂体地球物理响应特征是解释和标定含气砂体的主要依据 ,其振幅变化为基础的多参数综合分析技术 ,提供了区分砂体含气性方法。在区内当含气砂体的波阻抗小于其上下围岩 ,其顶底界面的反射呈上负下正、(视 )频率较低、振幅较强的特征 ,即含气砂体与上覆地层的波阻抗差越大 ,则反射波波谷的振幅越强 ;与下伏地层的波阻抗差越大 ,则反射波的波峰振幅越强。
In recent years,the shallow natural gas exploration and development in Sichuan Basin have entered into a new stage and its reserves and production are rapidly increased,which plays an important role in these respects as evaluation exploration,detailed 2-D and 3-D seismic interpretation,detailed reservoir description,reserve estimation and making up development plan,etc.In light of the practice of the shallow natural gas exploration and development and the detailed processing and interpretation of seismic data,it is shown that the geophysical response characteristics of shallow gas-bearing sandbodies are the major bases of interpreting and calibrating gas-bearing sandbodies.The method of differentiating the gas potential of the sandbodies may be determined by use of multivariable comprehensive analysis technique on the basis of a change in its amplitude.In this region,while the wave impedance of gas-bearing sandbody is smaller than its up-and-down sourrounding rocks,the reflection of its top-and-bottom interfaces shows the characteristics as a negative at top and a positive at bottom,relatively low (apparent) frequency and relatively strong amplitude,i.e,the larger the wave impedance difference between the gas-bearing sandbody and its overlying formation,the stronger the amplitude of reflection wave trough;the larger the wave impedance difference between the gas-bearing sandbody and its underlying bed,the stronger the amplitude of reflection wave crest.
In recent years,the shallow natural gas exploration and development in Sichuan Basin have entered into a new stage and its reserves and production are rapidly increased,which plays an important role in these respects as evaluation exploration,detailed 2-D and 3-D seismic interpretation,detailed reservoir description,reserve estimation and making up development plan,etc.In light of the practice of the shallow natural gas exploration and development and the detailed processing and interpretation of seismic data,it is shown that the geophysical response characteristics of shallow gas-bearing sandbodies are the major bases of interpreting and calibrating gas-bearing sandbodies.The method of differentiating the gas potential of the sandbodies may be determined by use of multivariable comprehensive analysis technique on the basis of a change in its amplitude.In this region,while the wave impedance of gas-bearing sandbody is smaller than its up-and-down sourrounding rocks,the reflection of its top-and-bottom interfaces shows the characteristics as a negative at top and a positive at bottom,relatively low (apparent) frequency and relatively strong amplitude,i.e,the larger the wave impedance difference between the gas-bearing sandbody and its overlying formation,the stronger the amplitude of reflection wave trough;the larger the wave impedance difference between the gas-bearing sandbody and its underlying bed,the stronger the amplitude of reflection wave crest.
引文
1 郭正吾 ,邓康龄等 .四川盆地形成与演化 .北京 :地质出版社 ,1 996
2 俞寿朋 .高分辨率地震勘探 .北京 :石油工业出版社 ,1 993
3 俞寿朋 ,董兆斌 ,梁杰 ,牛金松 .地震勘探中的分辨率和信噪比问题 .物探科技通报 ,1 984;2 (2 )
2 俞寿朋 .高分辨率地震勘探 .北京 :石油工业出版社 ,1 993
3 俞寿朋 ,董兆斌 ,梁杰 ,牛金松 .地震勘探中的分辨率和信噪比问题 .物探科技通报 ,1 984;2 (2 )
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