油气田开发中的四维地震技术

4-D seismic technique in oil and gas field development

在油气田开发中，制定加密井、注采等开采方案需要地下油藏动态变化方面的信息。以往大多利用井的资料作定性分析，虽然这种“硬”信息精确度高，但它们是一种相对稀疏的采样，不能给出油气藏特性变化的横向分布，而新发展起来的四维地震为油气田开发提供了一种新方法。它基于油藏开采过程中储层特性变化会引起地震反射特征（如波阻抗、反射时间、反射振幅等）变化这一理论，通过求取相隔一定时间二次地震数据之间的差值，来解释地下赌层特性的变化，给出连续的空间分布信息。近几年，四维地震技术在采集和处理技术上都有很大发展，在采集中采用固定埋置检波器的方法等；在处理中采用匹配滤波、道均衡等技术，以解决数据的可重复性，增强地震差异与储层差异之间的对应性。目前，四维地震技术主要用于蒸汽驱、火驱前线监测以及剩余油区的确定，在国外已取得较好的效果。

In oilfield development, the information on reservoir dynamic state is neded when arranging new wel positions and designing injection and recovery schemes. Previously, well data, whichhave a relatively high precision, were used as primary information for qualitative analysis of reservoir dynamic state. But they are relatively spe samoles, unable to demonstrate the latera distribution ofreservoir change. The newly developed 4-D seismic provide a new approach to oilfield develoment. It isbased on the principle that the change of reservoir characteristics in hydrocarbon production process willresult in the chang of seismic reflection charateristics (such as wave impedance, reflection time andamplitude). The difference of two sets of seismic data colected at different time is used to interpret thechange of subsurface reservoir characteristics and give information on continual spatial distribution of thechange. In recent years, 4-D seismic has a great progress in the aspects of acquisition and processing.For example, fixedly buried geophones, matched filtering, and trace equalization techniques have beenadopted to improve the repeatability of data and correspondence between seismic contrast and reservoircontrast. 4-D Sesmic techniques have been used primdrily for monitoring the front of vapour and fireflllding and determining resdual oil area, and good application effects have been achieved abroad.