瞬变电磁法在天山山前带表层调查中的应用——以XHBX三维工区为例
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摘要
天山北麓XHBX三维工区地表起伏剧烈,表层结构复杂,仅靠有限的地震微测井资料难以建立准确的表层结构模型;小折射受地表条件及薄高速夹层等因素影响无法观测到真实的校正界面;野外地震记录中初至前"旁瓣"及背景干扰严重,使基于初至的折射建模方法无法应用。为了获得准确的表层结构,采用瞬变电磁法(TEM)和地震微测井相结合的方法进行表层结构调查。首先通过一维"正演修正法"反演获得表层电性结构,然后利用地震微测井资料标定和非线性高阶多项式拟合将电阻率转换成速度,再经过Kriging网格化插值获得表层结构的速度和厚度平面分布,最终得到完整的三维近地表结构模型。应用该模型计算基准面静校正量并进行后续处理后,XHBX三维工区叠加剖面信噪比得到明显提高,反射同相轴连续性有了较大改善,中、长波长静校正问题也得到部分解决。
The XHBX3D block in the north of Tianshan is characterized by serious fluctuated surface and complex near-surface structures. The near-surface structure model cannot be accurately established only by using the limited uphole data.Affected by surface conditions and thin high-velocity interbed,accurate actual correction interface cannot be observed by minor refraction.In field seismic record, "side lobe" before first break and background interference are serious,so the refraction modeling based on first break cannot be applied.In order to obtain accurate surface structure,we combined transient electromagnetic method(TEM) with seismic uphole method.Firstly,surface electric structure was inversed by 1D "forward modeling correction".Then,resistivity was transformed into velocity by the calibration of seismic uphole data and the fitting of nonlinear high-order polynomial.Thirdly,the velocity-thickness distribution of surface structure in the plane was obtained by Kriging gridding interpolation.Finally,complete 3D near surface structure model was achieved.After applying the model to compute static amount and carry out subsequent processing,the S/N of stack profile was obviously enhanced,the continuity of reflection events was largely improved,and the static correction problem of middle-wavelength and long-wavelength were partly solved.
The XHBX3D block in the north of Tianshan is characterized by serious fluctuated surface and complex near-surface structures. The near-surface structure model cannot be accurately established only by using the limited uphole data.Affected by surface conditions and thin high-velocity interbed,accurate actual correction interface cannot be observed by minor refraction.In field seismic record, "side lobe" before first break and background interference are serious,so the refraction modeling based on first break cannot be applied.In order to obtain accurate surface structure,we combined transient electromagnetic method(TEM) with seismic uphole method.Firstly,surface electric structure was inversed by 1D "forward modeling correction".Then,resistivity was transformed into velocity by the calibration of seismic uphole data and the fitting of nonlinear high-order polynomial.Thirdly,the velocity-thickness distribution of surface structure in the plane was obtained by Kriging gridding interpolation.Finally,complete 3D near surface structure model was achieved.After applying the model to compute static amount and carry out subsequent processing,the S/N of stack profile was obviously enhanced,the continuity of reflection events was largely improved,and the static correction problem of middle-wavelength and long-wavelength were partly solved.
引文
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[2]黄俊明,苏朱刘,吴信全,等.中心回线瞬变电磁测深法在表层结构调查中的应用[J].江汉石油学院学报,2004,26(3):63-66
[3]苏朱刘,胡文宝.中心回线方式瞬变电磁测深虚拟全区视电阻率和一维反演方法研究[J].石油物探, 2002,41(2):216-221
[4]苏朱刘,罗延钟,胡文宝.大地电磁测深“正演修正法”一维反演[J].石油地球物理勘探,2002,37(2): 138-144
[5]苏朱刘,胡文宝.AB-s方式瞬变电磁测深资料处理方法研究[J].石油地球物理勘探,2002,37(3): 262-266
[6]苏朱刘,胡文宝.S-s方式瞬变电磁测深资料处理方法研究[J].地球物理学报,2002,45(增刊):400-409
[7]朴化荣.电磁测深法原理[M].北京:地质出版社, 1990:9-22
[8]薛为平,郑鸿明,其其格,等.瞬变电磁法在准噶尔盆地南缘东部台28井区近地表调查中的应用[J].新疆地质,2009,27(4):373-376
[9]薛国强,李貅,郭文波,等.从瞬变电磁测深数据到平面电磁波场数据的等效转换[J].地球物理学报, 2006,49(5):539-545
[10]杨长福,林长佑,陈军营,等.三维瞬变电磁近似反演[J].地震学报,2000,22(4):377-384
[11]侯贺晟,高锐,贺日政,等.盆山结合部近地表速度结构与静校正方法研究——以西南天山与塔里木盆地结合部为例[J].石油物探,2010,49(1):7-11
[12]邬达理,蔡俩,李佩,等.固定剥离面静校正技术在山前带模型试验中的应用研究[J].石油物探,2009,48 (5):515-520
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