子洲气田山2致密砂岩气藏单井流体识别方法及应用

The Well Fluid Identification Method and Its Application for Tight Sandstone Gas Reservoir of Shan 2 Reservoir in Zizhou Gasfield

子洲气田山2致密砂岩气藏气水分布复杂,在开发过程中,部分区块见大量水体产出,作为典型的岩性气藏,其气水分布受构造、砂体、储层物性和天然气成藏等因素影响,为此,综合考虑各种因素,开展单井流体识别方法及有效性研究。根据自然伽马—电阻率等常规交会图法,自然伽马可以明显区分干层与气层、水层,电阻率可以有效区分出气层与水层。应用常规交会图法、电阻率—孔隙度交会图法、P1/2累积频率法与多元判别方法对子洲气田山2段气层、水层、干层进行识别,认为上述方法共同应用可有效识别储层流体,其中,自然伽马—电阻率交会图和多元判别方法识别效果较好,其所建立的模型可用于研究区和邻区的流体识别。通过实际应用证明,上述方法共同应用于研究区进行气层、水层、干层的识别是有效的,对比试气结果可知,其回判的正确率达到95.8%,证实该方法准确性较高,对子洲气田气水层解释具有很好的效果,可以广泛应用于类似的邻近气藏。

The distribution of gas and water is complex for tight sandstone gas reservoir in Shan 2reservoir of Zizhou Gasfield.There is general water breakthrough during development in some regions.As a typical lithologic gas reservoir,this is dominated by structure,sand body characteristics,reservoir physical property and hydrocarbon accumulations.Therefore,given all sorts of factors,the fluid recognition method and effectiveness was researched.Based on the conventional cross-plot method of natural gamma-resistivity,natural gamma distinguished gas,water and dry layers clearly,and resistivity distinguished gas and water layers effectively.The conventional cross-plot method,the cross-plot of resistivity-porosity,P^1/2 cumulative frequency method and multiple discriminating methods are applied to identify the gas,water and dry layers.The result shows that these methods can effectively distinguish reservoir fluid.Among them,the identification effect of the natural gamma-resistivity and multiple discriminating methods are better,and the model can be used for fluid identification in the study and adjacent areas.The practical application approved that these methods used together to identify the gas,water and dry layers in the study area must be effective.Compared with gas testing results,the discriminating rates have reached 95.8%,which confirmed that this method has good accuracy.The above methods have a good effect on the gas and water interpretation,which can be widely used in similar adjacent reservoirs.