时频电磁法在冀中坳陷潜山及潜山内幕油气预测中的应用

Hydrocarbon prediction with TFEM in buried hills,Jizhong Depression

针对冀中坳陷文安斜坡—大城凸起地区潜山埋藏深度大、浅层干扰严重等勘探难点,应用时频电磁(TFEM)技术,对工区内潜山及潜山内幕油气进行研究。通过分析潜山油气藏电性特征以及潜山岩心测试结果,总结出潜山含油气时具有高振幅、高相位、中—低电阻率异常的特征,且含油饱和度越高三个参数的响应越强。通过扩展激发周期至40s获得了深部目标体的信息,采用多周期数据叠加有效提高了信噪比,并依据井、震资料建立模型进行约束反演,有效提取了潜山及潜山内幕油气异常信息,同时结合已知钻井和潜山油气藏异常特征对研究区的时频电磁异常进行了标定,在文安斜坡—大城凸起地区预测了六个潜山含油气有利区。预测结果得到了后期钻探数据的验证。这表明时频电磁勘探能够为油气勘探指明方向,降低钻探风险。

Because the buried hill in Wen'an slope and Dacheng uplift is deeply buried and shallow interference is violent,the time-frequency electromagnetic method(TFEM)is applied to study hydrocarbon potential in deeply-buried hills of the area.Based on electrical characteristics of buried hill reservoirs and core test results,it is concluded that buried hill reservoirs in this area show high amplitudes,high phase,and low to medium resistivity.And the higher oil saturation,the stronger these three parameters are.Deep target precision information is obtained with excited source extended up to 40 s.As a result,the signal-to-noise ratio is effectively improved by gathering multi-cycle data.Hydrocarbon anomaly of buried hills is effectively extracted by TFEM inversion constrained by geological model built on logging and seismic data.Combined with drilled well information,we predict six favorable buried-hill hydrocarbon zones in Wen'an slope and Dacheng uplift.Our prediction has been verified by the later drilling.