正则化等效层重力向下延拓方法

近年来，利用时移微重力技术进行储层开发监测受到国内外学者广泛关注.时移微重力观测数据存在信噪比低，信号弱的问题，难以实现储层内物质运移的定量解释.为压制数据噪声，增强有效弱信号，本文研究了利用Tikhonov正则化方法反演等效层（源），并由等效源实现重力场向下延拓的方法；在此基础上，本文推导了波数域正则化等效源向下延拓算子.针对向下延拓场幅值衰减问题，提出了正则化等效源迭代补偿算法.通过模拟数据实验研究了不同深度正则化等效源滤波算子及向下延拓算子的波数响应；与波数域Tikhonov正则化向下延拓方法相比，正则化等效源向下延拓方法的延拓精度更高、更稳定.最后，将基于迭代补偿的正则化等效源向下延拓技术应用于实测时移微重力数据证实了该方法能够有效增强局部异常，实现时移微重力数据大深度稳定向下延拓.

A study on gravity field downward continuation using the regularized equivalent-layer method

In recent years, dynamic reservoir monitoring technology using time-lapse microgravity method has been receiving much attention of researchers at home and abroad. As a result of the low signal-to-noise ratio (SNR) and weak signal in observation data, it is impossible to quantitatively interpret fluid migration in reservoirs using time-lapse microgravity data. In order to suppress observation noise and enhance weak signals, this article presents the regularized equivalent source downward continuation (RESDC) method, and derives the RESDC operator in the wavenumber domain. Besides, the iterative compensation algorithm is proposed to compensate for amplitude attenuation of the downward continuation field. With tests on synthetic data, this work further studies the wavenumber response of the filtering operators and the downward continuation operators of regularized equivalent layers at different depths. Results show that the downward continuation field of the RESDC method is more accurate and stable compared with the field from the Tikhonov downward continuation method. Applying the iterative compensation RESDC method to field data of a time-lapse microgravity survey verifies that the proposed method can effectively enhance weak signals and stably realizes large-depth downward continuation.