滩海浅层三维地震勘探技术
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摘要
在滩海过渡区域的浅层勘探中,形成了一套有效的地震资料采集、处理技术,并取得以下认识:①地震资料采集技术包括提高浅层覆盖次数的观测系统设计技术、提高分辨率的激发技术、气泡效应压制技术、水中检波器二次定位技术等内容。提高浅层覆盖次数的观测系统设计技术要求观测系统应具有小面元、小炮检距、小炮点密度的特点。提高分辨率的激发技术要求在水深小于2m的过渡带宜采用炸药震源激发,并采用浅井、小药量激发方式,遵循"枪数少、近组合"的原则针对不同的海域选取不同的气枪阵列组合,以较好地压制气泡效应,提高资料信噪比。水中检波器二次定位技术可准确地确定检波器的实际位置,是保证资料采集精度的重要环节。②地震资料处理技术包括水中检波器二次定位校正、手工切除动校正拉伸、子波匹配技术、海底鸣震压制处理、叠前时间偏移处理等内容。针对水中检波器漂移问题,利用声纳定位结果以及初至二次定位结果进行检波器位置校正,确定了检波器的真实位置,提高了资料处理精度。采用手工切除动校正拉伸,提高了浅层资料信噪比。子波匹配技术要求在CDP道集叠加前进行子波匹配滤波,以消除由于海、陆采集方法不同造成的地震子波差异,从而得到较好的叠加效果。采用两步法预测反褶积压制海底鸣震,使海底鸣震得到较好的衰减,剖面信噪比得到明显提高。通过叠前时间偏移成像处理,提高了复杂构造及5m断距的小断层的偏移成像精度。
During shallow exploration in transitional area of beach,a set of effective seismic data acquisition and processing method has been formed,acquiring following knowledge: ①②The seismic data acquisition technology includes following contents: geometry design technique improving shallow folds,shooting technique improving resolution,bubble effect-suppressed technique and secondary positioning technique of hydrophone.The geometry design technique improving shallow folds demands the geometry to be characterized by small bin-size,short offset,sparse density of shooting points;shooting technique improving resolution demands that using dynamite source for shooting is convenient in transitional belt where the water depth is less than 2m,and using the shooting mode of shallow well and small charge size and following the principle "less airgun number and short array interval" to select different airgun array according to different sea areas,the aim of which is to better suppress bubble effect and improve data S/N ratio.The secondary positioning technique of hydrophone can accurately determine the practical position of geophone and is important link ensuring data acquired precision.The seismic data processing technique includes following contents: secondary positioning correction of hydrophone,handy muting NMO stretch,wavelet match technique,sea-bottom singing suppressed processing and prestack time migration processing.In face to the drift issue of hydrophone,using sonar positioning results and secondary positioning results of first breaks to carry out correction of geophone position,determining true position of geophone and improving the data processed precision;handy muting NMO stretch is used to improve the S/N ratio of shallow data;wavelet match technique requires that the wavelet match filtering is carried out before CDP gather stack in order to eliminate the difference of seismic wavelet resulted from different land and marine acquisition methods,getting good stack results;using two-step predictive deconvolution to suppress sea-bottom singing can make the sea-bottom singing be better attenuated and greatly improve the S/N ratio of section;the migrated imaging precision of complex structure and minor fault with 5m separation can be improved by prestack time migration imaging processing.
During shallow exploration in transitional area of beach,a set of effective seismic data acquisition and processing method has been formed,acquiring following knowledge: ①②The seismic data acquisition technology includes following contents: geometry design technique improving shallow folds,shooting technique improving resolution,bubble effect-suppressed technique and secondary positioning technique of hydrophone.The geometry design technique improving shallow folds demands the geometry to be characterized by small bin-size,short offset,sparse density of shooting points;shooting technique improving resolution demands that using dynamite source for shooting is convenient in transitional belt where the water depth is less than 2m,and using the shooting mode of shallow well and small charge size and following the principle "less airgun number and short array interval" to select different airgun array according to different sea areas,the aim of which is to better suppress bubble effect and improve data S/N ratio.The secondary positioning technique of hydrophone can accurately determine the practical position of geophone and is important link ensuring data acquired precision.The seismic data processing technique includes following contents: secondary positioning correction of hydrophone,handy muting NMO stretch,wavelet match technique,sea-bottom singing suppressed processing and prestack time migration processing.In face to the drift issue of hydrophone,using sonar positioning results and secondary positioning results of first breaks to carry out correction of geophone position,determining true position of geophone and improving the data processed precision;handy muting NMO stretch is used to improve the S/N ratio of shallow data;wavelet match technique requires that the wavelet match filtering is carried out before CDP gather stack in order to eliminate the difference of seismic wavelet resulted from different land and marine acquisition methods,getting good stack results;using two-step predictive deconvolution to suppress sea-bottom singing can make the sea-bottom singing be better attenuated and greatly improve the S/N ratio of section;the migrated imaging precision of complex structure and minor fault with 5m separation can be improved by prestack time migration imaging processing.
引文
[1]王振东.浅层地震勘探应用技术.北京:地质出版社,1998
[2]余志和等.滩海地区采集方法研究.石油地球物理勘探,2001,36(4):471~478
[3]俞寿朋.高分辨率地震勘探.北京:石油工业出版社,1993
[4]李庆忠.走向精确勘探的道路.北京:石油工业出版社,1993
[5]陈浩林等.气枪阵列子波数值模拟.石油地球物理勘探,2003,38(4):363~368
[6]Ziolkowski A.Measurement of air-gun bubble oscilla-tions.Geophysics,1998,63(6):2009~2024
[7]於国平.海洋地震空气枪系统子波测试标准及方法.物探装备,2001,11(1):21~26
[8]冯凯等.二次定位技术的应用.石油地球物理勘探,2006,41(3):346~349
[9]杨惊涛等.海上二次定位技术的研究与应用.石油物探,2002,41(增刊):67~69
[10]李丕龙等.滩浅海地区高精度地震勘探技术.北京:石油工业出版社,2006
[11]曹孟起等.叠前时间偏移处理技术及应用.石油地球物理勘探,2006,41(3):286~289
[2]余志和等.滩海地区采集方法研究.石油地球物理勘探,2001,36(4):471~478
[3]俞寿朋.高分辨率地震勘探.北京:石油工业出版社,1993
[4]李庆忠.走向精确勘探的道路.北京:石油工业出版社,1993
[5]陈浩林等.气枪阵列子波数值模拟.石油地球物理勘探,2003,38(4):363~368
[6]Ziolkowski A.Measurement of air-gun bubble oscilla-tions.Geophysics,1998,63(6):2009~2024
[7]於国平.海洋地震空气枪系统子波测试标准及方法.物探装备,2001,11(1):21~26
[8]冯凯等.二次定位技术的应用.石油地球物理勘探,2006,41(3):346~349
[9]杨惊涛等.海上二次定位技术的研究与应用.石油物探,2002,41(增刊):67~69
[10]李丕龙等.滩浅海地区高精度地震勘探技术.北京:石油工业出版社,2006
[11]曹孟起等.叠前时间偏移处理技术及应用.石油地球物理勘探,2006,41(3):286~289
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