页岩气楔状模型储层的地震响应特征
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摘要
中国南方古生界页岩气储层分布面积广,碳质含量高,但是储层保存条件较差,受构造运动影响较大。为此设计了5种不同楔形模型研究其地震响应特征——地震子波主频对波场特征的影响;页岩体速度对波场特征的影响;页岩体顶、底界面坡度变化对波场特征的影响;地层夹角对波场特征的影响;顶底界面岩性组合对波场特征的影响。研究表明:地震子波主频增加,分辨能力提高;页岩体速度与围岩差异变大,反射同相轴振幅增强;楔状页岩体顶、底界面坡度变大,横向分辨率增大;对于梯变型页岩体,在厚度为四分之一波长处,相消干涉,反射能量最弱,振幅达到极小值。
The Paleozoic shale gas reservoirs in southern China cover a vast area. Their carbon content is high,but preserving condition rather poor because of tectonic movements. By this,different wedge models designed to study their seismic response characteristics,in cluding impacts from wavelet dominant frequency,wave velocity in shale mass,gradient variation of shale mass top and bottom interfac es,strata included angle and rock association at top and bottom interfaces to wave field features. The result has shown that wavelet dom inant frequency increasing,resolution improving; velocity difference in shale mass and country rock increasing,amplitude of reflection phase axis strengthening; gradient of wedgy shale mass top and bottom interfaces increasing,transverse resolution improving; to wedgy shale mass,when thickness is one quarter wavelength,destructive interference,reflected energy weakest,amplitude minimum.
The Paleozoic shale gas reservoirs in southern China cover a vast area. Their carbon content is high,but preserving condition rather poor because of tectonic movements. By this,different wedge models designed to study their seismic response characteristics,in cluding impacts from wavelet dominant frequency,wave velocity in shale mass,gradient variation of shale mass top and bottom interfac es,strata included angle and rock association at top and bottom interfaces to wave field features. The result has shown that wavelet dom inant frequency increasing,resolution improving; velocity difference in shale mass and country rock increasing,amplitude of reflection phase axis strengthening; gradient of wedgy shale mass top and bottom interfaces increasing,transverse resolution improving; to wedgy shale mass,when thickness is one quarter wavelength,destructive interference,reflected energy weakest,amplitude minimum.
引文
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[5]Mavor M.Barnett Shale Gas2in2Place Volume Including Sorbed and Free Gas Volume(abs.)[C].Fort Worth,Tex2as:AAPG Southwest Sec tion Meeting,2003.
[2]王冕冕,郭肖,曹鹏,等.影响页岩气开发因素及勘探开发技术展望[J].特种油气藏,2010年12月,第17卷第6期:12-16
[3]蒋裕强,董大忠,漆麟,等.页岩气储层的基本特征及其评价[J].地质勘探,2010,30(10):7-12.
[4]3D AVO crossplotting—An effective visualization technique[J].SAT INDER CHOPRA,VLADIMIR ALEXEEV,and YONG XU,THE LEAD ING EDGE NOVEMBER 2003.
[5]Mavor M.Barnett Shale Gas2in2Place Volume Including Sorbed and Free Gas Volume(abs.)[C].Fort Worth,Tex2as:AAPG Southwest Sec tion Meeting,2003.
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