激发极化法勘探油气藏的效果分析及改进意见

国内外利用激发极化法在油气藏上实测试验和实验室研究表明,深部储油构造引起浅层激电异常的主要地质因素是与油气藏上方浅部地层中的次生黄铁矿侵染带有关。黄铁矿化是由于碳氢化合物渗透到浅层孔隙围岩中,被细菌氧化产生还原型的硫化物,与围岩中的铁作用后形成的。文中论述了我国目前采用激发极化法探测油气藏成功率不高的原因,主要是油气藏激电异常受地质条件的约束及富含淡水岩层的激电效应的干扰;进而讨论了提高激发极化法探测油气藏效果的途径,并指出在油气藏开发区进行试验时应注意钻孔套管及地表管道的影响。

Effect and improvement of induced polarization method for hydrocarbon exploration,

Laboratory induced polarization study and field induced polarization experiments conducted over hydrocarbon traps show that the key geological reason why deep hydrocarbon trap results in shallow induced polarization (IP) anomaly is the shallow secondary-pyrite contaminated zone that overlies the hydrocarbon trap. Pyrite was formed because ferrite in shallow porous country rock combined with the sulphide which resulted from bacteria's oxidizing the hydrocarbon that had migrated from deep hydrocarbon trap to the country rock. It is pointed out that low success rate of IP hydrocarbon-trap detection in China mainly results from(1) the geological condition restriction on IP anomaly of hydrocarbon trap and (2) the interference due to the IP effect of freshwater-saturated formation. It is discussed how the effect of IP hydrocarbon-trap detection can be improved.The effects of hole casing and nearsurface pipes should be considered in IP experiment in oil-gas production area.