涩北气田弱水驱气藏水侵早期识别方法

弱水驱气藏开发早期的水侵特征不明显，识别起来比较困难。现场多采用水样监测和对水气比曲线进行分析等方法对气藏的水侵特征进行识别，但这些方法都是在地层水进入气井之后才能进行判断，不利于提前采取预防措施。以涩北二号气田边水能量较弱的A气藏为例，通过引入生产指示曲线法、存水体积系数法和视地质储量法对气藏早期的水侵特征进行识别，并通过不同采出程度下的曲线特征进行了对比。结果表明：视地质储量法对气藏水侵作用敏感性强，曲线发生上翘拐点时对应的采出程度最低，比现场经验法低20%；视地质储量法水侵识别结果可靠性高，能更早地发现气藏的水侵特征。该研究成果对于无裂缝发育、孔隙性相对均质的弱水驱气藏进行早期的水侵特征识别具有指导意义。

Early identification methods of water invasion in weak water drive gas reservoirs in Sebei gas field,Qaidam Basin

In the early stage of development of weak water drive gas reservoirs,the water invasion characteristics are not obvious,so it is difficult to identify them. Water monitoring and water-gas ratio curve analysis were often used to identify water invasion characteristics of gas reservoirs,but these methods can only be used after formation water enters gas wells,which is not conducive to taking preventive measures in advance. Taking A gas reservoir with weak edge water energy in Sebei No. 2 gas field as an example,the early water invasion characteristics of gas reservoir were identified by introducing production indicator curve method,water storage volume coefficient method and apparent geological reserves method,and the curve characteristics under different recovery degrees were compared. The results show that the apparent geological reserve method is sensitive to water invasion of gas reservoirs,and the corresponding recovery degree is the lowest when the curve warping point occurs, which is 20% lower than the field experience method. The result of water invasion identified by the apparent geological reserve method is more reliable,and the water invasion characteristics of gas reservoirs can be found earlier. The research results have guiding significance for early identification of water invasion characteristics of weak water drive gas reservoirs without fracture development and relatively homogeneous porosity.