海洋可控源电磁法二维反演研究

发布时间：2018-11-15 22:53

【摘要】：利用海洋可控源电磁法(CSEM)进行海洋石油勘探已经成为国际上的热点,CSEM法可以用来研究大洋地壳、调查海底沉积物分布和勘探海底油气资源。CSEM法可以通过观测油气藏和低阻围岩电阻率的差异所产生的电磁异常,确定油气储层的分布范围。在国外,海洋可控源电磁法的研究起步较早,发展比较迅速,而我国海洋电磁的研究则刚刚起步。因此,我国需要加强CSEM法的数值模拟和反演研究。本文详细分析了国内外海洋可控源电磁法正反演发展现状,在此基础上,推导了二维有限差分的基本公式,阐述了二维点源坐标下差分原理、面积离散法、网格剖分方法;实现海洋CSEM二维正演。利用有限差分二维正演程序,正演模拟了单棱柱模型,对比了不同深度、发射频率以及不同场分量、不同电阻率下的电磁响应。同时对不同油藏模型(背斜、断层和潜山油气藏)进行了正演模拟,分析了不同模型的电磁响应规律。在正演模拟的基础上,实现海洋可控源电磁的非线性共轭梯度反演。首先介绍了CSEM非线性共轭梯度方法,然后利用matlab编程实现海洋可控源电磁二维反演。对单棱柱模型和背斜油气藏模型进行了反演,反演结果表明,采用水平电场分量的实部和虚部可以较好地反演出高阻油气藏的横向位置和电阻率,垂向位置和垂向范围有一定的偏差。同时,本文还对实际可控源电磁数据进行了反演,结果表明,本文反演结果与测井和地震的结果一致性较好。
[Abstract]:Ocean oil exploration by using ocean controllable source electromagnetic method (CSEM) has become a hot spot in the world, and CSEM method can be used to study the oceanic crust. CSEM method can determine the distribution range of oil and gas reservoir by observing the electromagnetic anomaly caused by the difference of resistivity between oil and gas reservoir and low resistivity surrounding rock. In foreign countries, the research of ocean controlled source electromagnetic method started earlier and developed rapidly, but the study of ocean electromagnetic method in our country has just started. Therefore, our country needs to strengthen the numerical simulation and inversion research of CSEM method. In this paper, the current situation of forward inversion of ocean controllable source electromagnetic method is analyzed in detail. On this basis, the basic formula of two-dimensional finite difference is derived, and the difference principle, area discretization method and mesh generation method in two-dimensional point source coordinates are expounded. Ocean CSEM 2-D forward modeling is realized. The single prism model is simulated by using the finite difference two-dimensional forward modeling program. The electromagnetic responses of different depths, emission frequencies, field components and resistivity are compared. At the same time, the forward modeling of different reservoir models (anticline, fault and buried hill reservoir) is carried out, and the electromagnetic response of different models is analyzed. Based on forward modeling, nonlinear conjugate gradient inversion of ocean controllable source electromagnetic is realized. Firstly, the CSEM nonlinear conjugate gradient method is introduced, and then the 2-D electromagnetic inversion of ocean controllable source is realized by matlab programming. The inversion of single prism model and anticline reservoir model shows that the lateral position and resistivity of high resistivity oil and gas reservoir can be well reversed by using the real and imaginary parts of horizontal electric field component. There is a certain deviation between vertical position and vertical range. At the same time, the electromagnetic data of the controlled source are inversed in this paper. The results show that the inversion results are in good agreement with the well logging and seismic results.
【学位授予单位】：中国石油大学(华东)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P631.325

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