地球物理学进展 ›› 2021, Vol. 36 ›› Issue (5): 1927-1934.doi: 10.6038/pg2021EE0430

• 固体地球物理及空间物理学(大气、行星、地球动力学、重磁电及地震学、地热学) • 上一篇    下一篇

基于Lp范数(0<p<0.5)约束的裂陷盆地基底非线性重力反演

周少伟1,4(), 冯旭亮2,*(), 杨浩3, 魏泽坤2, 李菲1,4   

  1. 1.陕西省地质科技中心,西安 710065
    2.西安石油大学地球科学与工程学院,西安 710065
    3.中国冶金地质总局中南局,武汉 430035
    4.陕西省地质调查院院士专家工作站,西安 710065
  • 收稿日期:2020-12-05 修回日期:2021-05-23 出版日期:2021-10-20 发布日期:2021-11-11
  • 通讯作者: 冯旭亮 E-mail:zhoushaowei0125@126.com;fxlchd@163.com
  • 作者简介:周少伟,男,1988年生,硕士,工程师,长期从事地球物理勘探(重力、磁法、电法)数据采集、处理及解释等工作.E-mail: zhoushaowei0125@126.com
  • 基金资助:
    国家自然科学基金项目(41904115)

Nonlinear gravity inversion of rifted basement relief using Lp norm constraint with 0<p<0.5

ZHOU ShaoWei1,4(), FENG XuLiang2,*(), YANG Hao3, WEI ZeKun2, LI Fei1,4   

  1. 1. Shaanxi Geological Science and Technology Center, Xi’an 710065, China
    2. School of Earth Sciences and Engineering, Xi’an Shiyou University, Xi’an 710065, China
    3. Centralsouth Bureau of China Metallurgical Geology Bureau, Wuhan 430035, China
    4. The Academician Expert Workstation of Shaanxi Institute of Geological Survey, Xi’an 710065, China
  • Received:2020-12-05 Revised:2021-05-23 Online:2021-10-20 Published:2021-11-11
  • Contact: FENG XuLiang E-mail:zhoushaowei0125@126.com;fxlchd@163.com

摘要:

利用重力反演沉积盆地基底起伏是油气重力勘探研究的一个重要方面.随着地质目标勘探难度逐渐增大,亟需提高重力反演盆地基底的精细程度.本文研究了基于Lp范数约束的非线性重力反演方法,反演结果能更好地符合裂陷盆地基底起伏特征.反演时假设沉积盆地基底和沉积层均为单一岩性,即沉积层与基底的密度差为常数.将基底之上的沉积层剖分为垂直并置的棱柱体,用棱柱体底面深度近似沉积盆地基底深度,其为待反演的参数.利用Ekblom范数近似Lp范数的表达式,并建立Lp范数意义下的参数向量函数,将其与重力误差函数结合得到非线性反演的目标函数.利用二维裂陷盆地模型进行试算,结果表明当p取0.2时能较准确的反演裂陷盆地基底起伏形态,其应用效果优于基于L0范数和L1范数的约束反演方法.将本文方法应用于南海珠江口盆地实际重力资料反演,将反演的基底深度与地震剖面解释结果进行对比,结果表明该反演方法具有较好的实用性.

关键词: 重力异常, 裂陷盆地基底, Lp范数, 非线性反演

Abstract:

Estimating the depth of a sedimentary basin is a main task in oil and gas exploration using gravity data. With the increasing difficulty of exploring geological target, the precision of basement inversion using gravity is required to be higher and higher. We developed a nonlinear gravity inversion method for estimating the depth of a rifted basement using Lp norm constraint. The sediments and the bed rocks are assumed to be both homogeneous, that is, the density contrast between the sediments and the basement is constant. We divided the sediments above the basement into vertical juxtaposed prisms whose bottom depths are in line with the depth-to-basement and are the parameters to be estimated. The Ekblom function is used to approximate the expression of the Lp norm. We establish the constraint function of the parameter vector with Lp norm and combined it with the gravity data misfit function to form the objective function for nonlinear inversion. A 2D rifted basement model is introduced to test the correctness of our proposed method, and the result shows that the rifted basement can be perfectly recovered with p=0.2. Moreover, the inverted result with our proposed method is superior to the results under the L1 norm and L0 norm constraint. We have applied the proposed method to the real gravity data of Pearl River Mouth Basin, South China Sea, the comparison between the inverted basement with gravity data and the interpreted basement using seismic profile confirm the practicability of our developed method.

Key words: Gravity anomaly, Rifted basement, Lp norm, Nonlinear inversion

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