四川盆地北部地区飞仙关组测井相特征

Logging facies characteristics of Feixianguan Formation,northern Sichuan Basin

四川盆地下三叠统飞仙关组长期以来一直是四川盆地礁滩气藏勘探的重点层系,对于其沉积模式的研究已基本成熟,随着勘探工作的进一步深入和精细化,在取心普遍缺乏的情况下如何快速准确对新钻井沉积相进行初步分析是生产上亟须解决的问题之一。为此,通过对四川盆地北部地区大量钻井资料的统计对比,系统总结飞仙关组不同沉积相的测井响应特征,建立相应的测井相模型。研究结果表明:①通过岩心、成像测井标定,不同沉积相(亚相)在自然伽马曲线上具有典型的响应特征,不同沉积相(亚相)对应相应的曲线形态以及自然伽马区间值;②不同沉积相(亚相)的测井相模型在横向上可对比性较好,全区对比可操作性强;③通过对岩性、岩相剖面及相应测井相剖面的纵横向对比,发现二者匹配度较高。结论认为,采用常规自然伽马测井曲线对四川盆地北部地区飞仙关组沉积环境进行判别具有实际的可操作性,且准确性高,在岩心资料缺乏、录井资料较差以及其他分析工作尚未开展的情况下,可充分应用于研究区新井前期地质分析工作,为确定勘探目标提供参考。

The Lower Triassic Feixianguan Formation has long been an exploration focus of bioreef-shoal gas reservoirs in Sichuan Basin.And the research on its sedimentary model has been basically mature.With further deepening its exploration with specific implementation,how to make quick and accurate preliminary analysis on sedimentary facies for newly drilled wells is one of the most urgent problems to be solved while no coring.Therefore,based on a large amount of drilling data from northern basin,some logging response characteristics of different sedimentary facies in Feixianguan Formation were systematically summarized,and corresponding logging facies models were established.Results show that,(1)through core and imaging logging calibration,different sedimentary facies and subfacies representing typical response characteristics on natural-gamma curves,are respectively corresponding to curve morphology and natural-gamma interval value;(2)these logging facies models can be compared with each other;and(3)after lateral and vertical comparison,lithologic and lithofacies profiles highly coincident with corresponding logging facies profiles.It is concluded that,for Feixianguan Formation in northern Sichuan Basin,to identify its sedimentary environment via using natural-gamma logging is practicable and accurate;even if there is no core data and other analytical work,as well as poor mud-logging data,this identification can be merged into preliminary geological analysis on new wells in the study area in order to provide reference for determine exploration targets.