低阻油气层成因及测井识别评价方法分析

Analysis of genesis of low resistivity oil gas layer and its logging identification evaluation

低阻油气层与邻近水层相比,岩性和孔隙度测井特征相似,电阻率测井差异小,甚至基本一致,造成油气层和水层区分困难。随着勘探开发的不断深入,国内陆上和海域主要含油气盆地中均已发现低阻油气层,为勘探开发带来可观的储量产量和经济效益,因此迫切需要总结其成因及测井识别评价方法。地质成因包括岩性因素、储层因素、地层水矿化度、低幅度圈闭和油气性质等;工程成因包括钻井液侵入、测井仪器和钻井工艺等。双电阻率法、视地层水电阻率法、自然电位减小系数法和测井曲线特征集法等7种实用低阻油气层测井识别方法大大提高了测井解释准确度。开展以饱和度为核心的低阻油气层定量评价,建立W-S和三水饱和度模型。

Compared with the adjacent water layer, the low resistivity oil gas layer has similar logging characteristics in lithology and porosity, also have small difference of resistivity in logging, so ii is difficult to differentiate water layer from oil gas layer. Along with the deepening of exploration and development, the low resistivity oil gas layer have been found in main oil and gas bearing basins in land and sea area, it will bring on considerable reserves, output and economic benefit for the exploration and development, so it is necessary to summarize the genesis of low resistivity oil gas layer and its logging identification evaluation. The geological genesis include lithology, reservoir, formation water salinity, low amplitude trap and oil gas property, and the engineering genesis include the drilling fluid invasion, logging instruments and drilling technologies. Seven methods （double resistivity, apparent formation water resistivity, spontaneous potential decreasing coefficient method and the method of well logging curves features and so on） are successively put forward to identify the low resistivity oil gas layer, the accuracy of logging interpretation is improved greatly. The quantitative evaluation of low resistivity oil gas layer, which is at the core of saturation, is successively put forward, and the W-S and three water saturation models are established.