测井资料在松辽盆地岩性储层预测中的应用

Application of logging data in synthetically predicting lithologic reservoir of northern Songliao basin.

松辽盆地北部YX地区砂泥岩薄互层中砂岩的有效厚度在2～5m之间,多小于调谐厚度,而且由于波阻抗差异较小,使得砂泥岩难以区分。通过对测井资料的分析,发现对砂岩较为敏感的测井曲线是电阻率曲线和自然伽马曲线。在有效砂岩处自然伽马呈现出比围岩更小的值,电阻率呈现比围岩更大值。为此,在每一条测井曲线上寻找有效砂岩与围岩的分界线,并读取值,然后以其均值为基值,采用平移法对测井曲线逐一进行归一化,消除系统误差。砂泥岩门槛值在基值附近按沉积环境的影响进行优选,采用随机模拟技术中序贯高斯模拟法进行储层预测,得到的有效砂岩厚度图与沉积环境和实际值吻合。最终结合物性、试油、测井等资料确定了油气、水、干层识别图版,从而进一步提高了岩性识别和储层预测的可靠性。

In the sandstone/mudstone interbedding strata of YX area, northern Songliao basin,the effective thickness of sandstone is 2～5 m.Most of the sandstone is smaller in thickness thanthe tuning thickness and has a small difference in wave impedance,making it difficult in recognizing sandstone and mudstone.Through analysis of logging data,resistivity curve,and spontaneous gamma curve were found sensitive to sandstone.The spontaneous gamma of ef- fective sandstone is smaller than that of surrounding rock and its resistivity is bigger than that of the later one.Therefore,the boundary of effective sandstone and surrounding rock is found on every logging curve and the value is read.Then,the average value is set as the basic value;paralleling method is utilized to normalize logging curves to eliminate system error.When the threshold value of sandstone and mudstone approaches the basic value,it is opti- mized according to the affection of sedimentary environment.The sequence Gauss simulation method was also utilized in reservoir prediction.The obtained effective thickness map and sedimentary environment are in good accordance with the actual data.Finally, combined with physical properties,testing and logging data,the recognition plate of oil/gas,water and dry layer was identified, further improving the reliability of lithology recognition and reser- voir prediction.