四维地震及其实施要求

四维地震,即时延三维地震,是近年来发展起来的一项储层开发和管理新技术。该技术研究的是地下储层中流体变化所引起的时延三维地震资料的差异,要求其资料的采集和处理具有重复性或一致性;它与并资料和开发史等资料(例如从开发并中获得的压力、声波和温度等)综合可以十分精确地测量地下反射系数、压力、温度、储层的生产能力和储层流体变化;并通过对泄油路径和剩余油的成像,提高钻井成功率,大大增加油气开采率。四维地震技术并非适用于所有储层,只有孔隙流体和岩石的压实变化大、温度变化大、压力变化大、净超负荷压力小且储层埋深浅,以及储层所有变化的综合效应在给定的地震分辨率范围内存在地震差异时,才能成功地应用四维地震技术。为取得应有的经济效益,四维地震实施应分可行性研究、现场先导试验和油田大规模应用三个阶段进行。目前,四维地震的成功实例都集中在"现场先导试验"阶段。

4-D SEISM AND ITS BASIC REQUIREMENTS

4-D seism, also known as time-delay 3-D seism, is a new technique for reservoir development and management. Its main task is to study the differences between time-delay 3-D seismic data caused by fluid changes in reservoirs. So time-delay seismic data must have repeatability or identity. Be combined with well and development history data,4-D seismic data can provide more accurate reflection cocfficient, temperature, pressure, productivity capacity andfluid changes of reservoirs. This technique can also improve recovery rate and well-drilling success ratio. But it must bepointed out that this technique is not suitable for all reservoirs. It only suitable for the reservoirs whose pore fluid, rockcompaction and pressure change considerably, the net-overload pressure is small and reservoirs are buried shallower,and there are seismic differentiae in given range of seismic resolution of reservoirs, synthetic effect. In order to gain itsproper economic benefit, the operation of 4-D seism will be carried out into three stages: 1. feasible study, 2. forerunningtest in site, and 3. oilfield application on a large scale. At present, all successful examples of 4-D seism focus on forerunning test.