传统观点认为定容气藏生产指示曲线呈直线,水驱气藏生产指示曲线上翘,异常高压气藏生产指示曲线下弯.南海崖城13-1气田是一个正常压力系统的边水气藏,但其北块气藏的生产指示曲线却出现了下弯现象.以崖城13-1气田北块气藏为研究对象,进行了生产指示曲线下弯原因及敏感性分析,在此基础上对异常高压气藏生产指示曲线进行了重新认识,结果表明:该气藏生产指示曲线下弯的本质是上凸,主要原因是水侵能量补给,其次是变容补给;在实际气藏的开发前期,生产指示曲线可能会表现出上翘特征,但最后也会下弯,因此传统认为的水驱气藏生产指示曲线上翘仅适用于强水驱气藏开发前期;异常高压气藏是特殊的有限封闭水体气藏,其生产指示曲线不是分段的,而是光滑下弯,本质上也是由能量补给导致的上凸,其岩石压缩系数很高是忽略水体造成的假象.本文研究成果对水驱砂岩气藏开发规划和采收率标定具有指导和借鉴意义.%It is traditionally believed that production index curve of water drive gas reservoir raises while that of abnormal high pressure reservoir drops.North block of YC13-1 gas field is a normal pressure system, but its production index curve presents drop characteristics.Taking north block of YC13-1 gas field as a case, the reasons of production index curve drop and sensitivity analysis are carried out, and new understandings of production index curve of abnormal high pressure reservoir are achieved.Results show that production index curve drop is caused primarily by water invasion and partially by volume variable energy supply, and the production index curve is essentially convex.In gas reservoir development, production index curve may raise in early stage and go down in later stage.Thus, the traditional theory of production index curve can only be applied in the early development stage of strong water drive gas reservoir.For abnormal high pressure gas reservoir, production index curve smoothly downwards instead of being segmented, but it is essentially convex due to restricted and closed water aquifer.High rock compressibility is an illusion caused by neglecting aquifer.The new understandings can provide reference for future development planning and recovery calibration of water flooding sandstone gas reservoir.
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