塔河油田缝洞型油藏注水替油井失效特征及其影响因素

Failure characteristics and influencing factors analysis on water injection for oil wells in fractured-vuggy reservoir

塔河油田实施注水替油生产是单井缝洞单元提高采收率的主导技术,但是失效井比例逐步增大,极大影响了注水开发效果。在分析该油田注水替油改善开发效果作用机理的基础上,对注水替油井进入失效阶段的主要动态特征进行了总结。结果表明,溶洞型、裂缝—孔洞型、裂缝型3类储集体注水替油井失效特征存在明显差异,但整体上裂缝型储集体注水替油井较溶洞型和裂缝—孔洞型更易失效;注水替油井进入失效阶段的主要动态特征为周期含水率快速上升、注水指示曲线斜率明显增大、周期存水率逐渐减小、周期吨油耗水比急剧增大。影响注水替油井失效的主要客观因素为单井储集体类型和注水替油后期的底水入侵;主观因素为周期注水量偏大和阶段焖井时间短导致的周期注采参数不合理。

The waterflooding and replacing oil is currently the chief method of enhancing oil recovery in the single well fracture-vuggyunits in Tahe oilfield. But, the proportion of failure wells increases gradually, and then it influences greatly the effect of waterfloodingperformance. Through analyzing the mechanism of water injection for oil to improve the development effect and combined with the pro-duction characteristics, the main failures can be summarized. The main characteristics that may cause the wells ineffective are, the wa-tercut rising quickly, the upturned of cyclic water injection instruction curve, the gradually decrease of the cyclic water storage rate, thedramatically increase of the cyclic water replacing for a ton of oil. For the water injection wells, the main objective causes accountingfor the failure are: reservoir type of individual well and bottom water intrusion in late stage of water injection to replace oil; and toomuch injection of cyclic water injection in wells, and inappropriate cyclic injection production parameters caused by insufficient soak-ing subjectively.