珠江口盆地陆丰凹陷文昌组FLAIR录井解释新方法

FLAIR new mud logging interpretation method for Wenchang Formation in Lufeng sag,Pearl River Mouth Basin

陆丰凹陷古近系文昌组为低孔隙度、低渗透率储层,测录井响应异常幅度降低,而文昌组泥岩多为成熟烃源岩,气测异常幅度较大,常接近甚至高于相邻储层,干扰了油气水层识别,导致常规录井解释方法准确率降低,难以准确区分储层流体性质。在气体比率法、流体指数法基础上提取了FLAIR新参数比率差值η1c和流体性质系数η2,结合计算全烃峰基比,建立了文昌组流体解释图板,并采用Fisher判别分析法确立了文昌组区域性定量解释模型,其在现场实际应用效果较好,录井综合解释符合率达到97.5%。

The reservoir of Paleogene Wenchang Formation in Lufeng sag is low in porosity and permeability,and the abnormal amplitude of logging response decreases.However,the mudstone in Wenchang Formation is mostly mature source rock,and the anomaly range of gas logging is large,which is often close to or even higher than the adjacent reservoirs,interfering with oil,gas and water layers identification,resulting in a reduced accuracy of the conventional mud logging interpretation method,it is difficult to accurately distinguish the reservoir fluid properties.Based on the gas ratio method and fluid index method,the new FLAIR parameters,ratio differenceη1c and fluid property coefficientη2 are extracted.Combined with the calculation of the peak to base ratio of total hydrocarbon,the Wenchang Formation fluid interpretation chart is established.The regional quantitative interpretation model of Wenchang Formation is set up by Fisher discriminant analysis,which has good effects in field application,and the coincidence rate of mud logging comprehensive interpretation is up to 97.5%.