非改造措施引起的负表皮现象原因分析

Analysis of Negative Skin Factor in Well Test in Non-Treatment Well

试井解释中,表皮系数为负值时,通常认为井筒附近的流体流动性得到改善提高。但有时没有任何的储层改造措施,测试过程产量也不高,地层也不属于疏松地层,成像测井也没有裂缝显示,仍计算得到负表皮系数的现象,给试井解释带来困扰。通过分析试井解释的处理解释环节发现,不确定性的产量、不正确的径向流位置选择以及新型的射孔弹技术会导致负表皮系数的出现。通过分析非地层污染引起的负表皮系数产生原因,提出了可靠的产量数据提供、正确的解释模型选择、精准的径向流定位、全面的射孔信息收集等规避错误解释的方法。

In well test interpretation,negative skin factor generally shows the flow ability is improved in the vicinity of wellbore.But the phenomenon of negative skin factor will be calculated though without reservoir stimulation treatment,just middle-low production rate in testing operation,non-unconsolidated formation and no fissure characteristic from imaging logging,which perplexes data interpreter.Through analysis of the interpretation of test well interpretation,it is found that the production of uncertainty,the selection of the incorrect radial flow position and the new technology of perforation can lead to the appearance of negative skin coefficient.By analyzing the reason of the formation pollution caused by negative skin factor,methods to avoid mistakes interpretation are put forward such as the reliable production of data,the correct interpretation model selection,the precise radial flow localization,comprehensive perforating information collection.