油气勘探中的地震速度泡沫(Fizz)现象

Fizz gas phenomenon in exploration of oil & gas

地下岩石孔隙中含有天然气会造成地震波传播速度的下降,但是这种含气量与速度下降量之间的关系一直没有被很清楚地认识到,因此造成很多勘探和开发上的决策失误.本文通过对Wood方程和Gassmann-Biot理论分析,定量地描述了岩石孔隙中天然气含量与波速之间的关系,叙述了由于极少量气造成很大速度变化的“速度泡沫”(Fizz gas)现象以及对这种速度假象进行识别的方法,并通过对中国某油田XD区块的实例研究验证了这种现象的存在及识别.

Seismic velocity decrease can be caused by pore rock bearing gas, but the relation between amount of the gas staying in the pore and the decrease amount of the velocity has not been recognized clearly, therefore, many mistakes have been made in exploration and production of oil and gas. Based on analysis to Wood equation and Gassmann theory, the quantitative relations between those two amounts have been described in this paper, and stated the ＂Fizz gas＂ phenomenon that cause large variation of velocity by little gas and how to discriminate this feint from real anomaly, finally to proved this phenomenon by real instance.