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

Application of transient electromagnetic method on 3D surface structure investigation of mountain front area in Xinjiang

(1．中国石油天然气股份有限公司新疆油田分公司勘探开发研究院地球物理研究所，新疆乌鲁木齐830013；2．油气资源与勘探技术教育部重 点实验室(长江大学)，湖北荆州434023；3．正通诚信科技开发有限公司，新疆乌鲁木齐830016)

Liu Yiwen,Institute of Geophysics,Xinjiang Oilfield Company,PetroChina,Urumqi 830013,China

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.

10.3969/j.issn.1000-1441.2001.05.013