四川盆地杂卤石地球物理响应特征及预测方法研究——以川中广安地区为例

川中南充盐盆是四川盆地最大的次一级含盐盆地,区域内钾盐具有成盐厚度大、分布范围广、埋藏深度深、岩性复杂等特点,目前尚未建立一套适用于研究区的钾盐地球物理评价方法。以地球物理勘探原理为基础,结合测井、录井、地质、地震等资料,分析和总结出不同岩性的测井响应特征以及分布范围,根据杂卤石"三高一低"的特点,建立杂卤石测井识别方法。在此基础上,优选伽马和声波速度作为敏感参数,建立了杂卤石的地质—测井—地震三位一体井约束地震反演识别方法,并以广参1井为例,预测杂卤石的空间展布情况。最后结合地震反演结果圈定出广安地区为杂卤石沉积的最有利区域。在实际应用中总结出一套适用于研究区的杂卤石预测方法,为研究区后续勘探开发提供了借鉴与参考,具有一定的推广应用价值。

Research on Geophysical Reponse Characteristics and Prediction Method of Polyhalite in Guang'an Area of Sichuan Basin

Nanchong Salt Basin is the largest secondary salt-bearing basin in Sichuan Basin, and potassium salt in this area has the characteristics of large salt-forming thickness, wide distribution, deep burial depth and complex lithology. At present, a set of geophysical evaluation methods for potassium salt in the research area have not been established. Based on the principle of geophysical exploration, combined with logging, mud logging, geology and seismic data, this paper analyses and summarizes the logging response characteristics and distribution range of different lithologies, and establishes the logging identification method of polyhalite according to the characteristics of polyhalite "three high and one low". On this basis, gamma and acoustic velocity are selected as sensitive parameters to establish a geology-logging - seismic constrained inversion identification method for polyhalite, and take GuangShen 1 well as an example to predict the spatial distribution of polyhalite. Finally, combined with seismic inversion results, the most favorable area for polyhalite deposits in Guang"an area is delineated. This paper summarizes a set of polyhalite prediction methods suitable for the study area in practical application, which provides reference for further exploration and development, and has a certain application value.