地震勘探技术在煤系非常规气富集区预测中的应用

Application of seismic exploration technology in forecasting unconventional gas enrichment area of coal measures

为了预测鄂尔多斯盆地东缘某勘探区煤系非常规气的资源富集区,采用地震勘探方法在这一新领域进行预测。首先,利用叠后波阻抗反演技术对储层进行岩性预测,通过波阻抗阈值得到样点个数,再与采样率计算出时间厚度,然后乘以岩层速度得到岩层厚度;其次,采用叠前AVO反演技术对储层进行含气性预测,经过分析含气饱和度与AVO相关属性参数之间的关系,得出与有利含气区敏感性最高的属性特征。最后,把储层厚度较厚和呈低拟泊松比属性特征的区域划定为各层含气有利区,并对勘探区下石盒子组八段、山西组和本溪组的砂岩气和页岩气进行了富集区预测,钻井验证效果较好。资源富集区的预测结果表明,地震勘探技术在该区域对煤系非常规气这一新领域的预测是可行的,此方法对其他区域煤系非常规气资源富集区的预测有借鉴意义。

For forecasting unconventional gas enrichment area in coal measures of eastern Ordos basin,seismic exploration was used to forecast the gas in this new field.First of all,it took the post-stack impedance inversion to forecast the lithology of the reservoir,it can get the number of sample points from the impedance threshold,and get the thickness of time by calculating the sampling rate,after that it can get the strata thickness by multiplying the thickness of time and the velocities of strata;second,it took the pre-stack AVO inversion to forecast the lithology gas-bearing properties of the reservoir,based on analyzing the relationship between gas saturation and the related AVO attribute parameters,we got the most sensitive attribute parameter of the favorable gas bearing areas.At last,it took the thicker reservoir and the low pseudo-Poisson’s ratio attribute feature as the favorable gas bearing areas,and it forecasted the enrichment area of sandstone gas and shale gas in eighth member of Shihezi Formation,Shanxi Formation and Benxi Formation of the exploration area,and drilling verified that the effect is good.The result of forecasting the enrichment area shows that seismic exploration forecasting this new field of unconventional gas enrichment area in coal measures in this region is feasible,and this method has a reference meaning for forecasting unconventional gas enrichment area in coal measures in other areas.