双相介质BISQ地震油气预测技术

Seismic hydrocarbon detection based on the unified Biot and squirt-flow mechanism (BISQ) model of two-phase medium

单相介质理论针对固体而忽视流体,预测油气则先天不足。双相介质理论指出流体尤其是油气的存在和运动是弹性波频散和衰减的主要原因,因而可以通过计算频散谱和衰减谱来预测油气。谱的计算要求有瞬时特性,才能避免时窗效应。为此采用分频的办法对地震道进行分频,形成分频道集后再作"三瞬"处理,这样在指定时刻一个釆样点可集合成瞬时振幅谱、瞬时频率谱、瞬时相位谱;用瞬时振幅谱和瞬时频率谱计算出瞬时衰减谱,而瞬时频散谱则可用瞬时相位谱去近似代表。通过已知井建立预测模型,再对6个待钻井位目标用该方法进行预测,完井试油预测成功率达83.33%。

The single phase theory is inefficient in hydrocarbon detection because it only studies solid without considering the fluids it contains.In contrast,two-phase medium theory suggests that the existence and movement of fluids,especially hydrocarbons,are the main cause of dispersion and attenuation of elastic waves,making it possible to detect hydrocarbons through calculating dispersion spectrum and attenuation spectrum.The calculation of spectrum needs instantaneity to avoid time window effect.Seismic traces are processed through frequency division and the frequency-division gathers are further processed to obtain instantaneous amplitude spectrum,instantaneous frequency spectrum and instantaneous phase spectrum on one sampling point at a given time.The instantaneous amplitude spectrum and frequency spectrum are then used to calculate instantaneous attenuation spectrum,while the instantaneous phase spectrum can be used as an approximation to instantaneous dispersion spectrum.The prediction model based on the available well data was used to identify targets of six planned wells,and up to 83.33% of the prediction results were in coincidence with the formation testing results.