The results show that the oil layer has low amplitude normal or negative anomaly SP and the water layer has large amplitude positive anomaly SP under the brine drilling fluid.

• 结果表明，适当的盐水钻井液条件下油层自然电位呈小幅度正异常或小幅度负异常，与水层自然电位呈大幅度正异常有很大差异。