压裂井高效返排技术的完善及应用

川西气藏具有低渗、致密、压力低的特点，常规压裂后返排时间长，返排率通常较低，势必要求加快排液速度，降低对储层的伤害。通过多年的探索和研究，发展了一套高效返排技术:液氮助排＋纤维防砂＋优化放喷技术，探讨了液氮降滤、助排－纤维固砂和携砂的机理，优化了液氮加量、纤维加量和放喷油嘴尺寸，并对液氮的加入方法进行了优化研究，完善了该套返排技术。在川西进行了6口井现场应用，施工成功率100％，24 h内返排率均达到68％以上，返排中未见出砂现象，增产效果显著。该技术的完善和应用，为同类气藏的高效开发提供了很好的思路。

Perfection and application of efficient flowback technology for fracturing wells

Gas reservoirs in west Sichuan are featured by low-permeability, tight and low pressure. Long flowback time after conventional fracturing and low fluid cleanup rate require for improving the flow back rate of the fracturing fluid to decrease the formation damage. A novel efficient flow back technology was developed that integrated liquid nitrogen cleanup, fibre sand control with open flow optimization technology through many years’ exploration and research. This paper discusses the mechanism of filtration reducing and cleanup with liquid nitrogen and sand consolidating and carrying with fibre. The amount of liquid nitrogen and fibre and choke size are optimized and adding method of liquid nitrogen is studied deeply as well. Thus flow back technology is improved. Field application in 6 wells in west Sichuan achieved operation success ratio of 100%, returning efficiency of 68％ in 24 hours, with no sand during flowback and stimulation effect was remarkable.The perfection and application of this technology offer a good clue for efficiently developing similar gas reservoirs.