东方1-1气田低电阻率气层测井评价方法

莺歌海盆地东方1-1气田发现了众多低阻气层，其三孔隙度曲线“镜像”不明显，地层电阻率接近临近水层和泥岩的值，难以有效识别。为此，从储层岩性、孔隙结构以及地层水性质等方面对低阻气层的成因机理进行了研究，在明确了低阻气层成因的基础上，提出了利用四孔隙度差值法、四孔隙度比值法对低阻气层进行定性识别方法；依据导电效率模型对低阻气层含水饱和度进行了计算，结合孔隙度与气柱高度计算得到的束缚水饱和度，可以据此有效地对低阻气层的产液性质进行判断。实际应用结果表明，该方法在东方1-1气田低阻气层解释评价中取得了良好的效果，与测试结果相吻合。

Logging evaluation methods for low-resistivity gas layers in the Dongfang 1-1 Gas Field,Yinggehai Basin

Numerous low-resistivity gas layers have been found in the Dongfang 1-1 Gas Field,Yinggehai Basin.In the tri-porosity logging plot,the mirror image is extremely vague,from which a gas layer is hardly recognized because its resistivity is quite close to that of the neighboring aquifer or mudstones.In view of this,the genesis of a low-resistivity gas layer is studied in terms of petrophysical properties,pore structures,formation water quality,etc.On this basis,a qualitative identification method is presented for low-resistivity gas layers by use of the quadra-porosity difference and ratio methods.Then,the water saturation of a low-resistivity gas layer is calculated according to the electrical efficiency model,and in combination with the porosity and gas column height,the saturation of irreducible water is finally obtained,which is a valid index for the determination of the properties of produced fluids in the low-resistivity gas layers.Good results have been achieved in the logging interpretation and evaluation of the low-resistivity gas layers in the Dongfang 1-1 Gas Field,which agrees well with the actual measurement.