大牛地气田液氮伴注效果分析及优化

Effect analysis and optimization of liquid nitrogen injection in Daniudi Gas Field

大牛地气田具有低渗、致密、低压的特点,在压裂施工中,通常存在压后返排困难、压裂井自然喷通率低的现象。采取较高液氮伴注比例压裂层位的水平井自然喷通率较高,然而一味地提高液氮比例会增加生产成本。文中在最小液氮伴注比例计算的基础上,考虑了启动压力梯度对压裂液返排的影响,得出了大牛地气田液氮伴注压裂井压后自然喷通的最小液氮用量评价模型,并给出了大牛地气田盒1气层压裂井压后自然喷通的最小液氮伴注比例,为大牛地气田液氮伴注压裂施工提供了参考。

Daniudi Gas Field has the reservoir characteristics of low permeability, dense and low pressure. In the process of fracturing operation, there is usually a difficulty in flow back and a low ratio of the flowing well. The layers that have a higher ratio of liquid nitrogen have a higher ratio of the flowing well. However, tile production cost will be raised if the ratio of liquid nitrogen is raised unlimitedly. On the basis of the calculation of minimum liquid nitrogen, the starting pressure gradient is considered and the evaluation model of the minimum liquid nitrogen ratio of the flowing well is built. The minimum liquid nitrogen ratio of He 1 gas layer of Daniudi Gas Field is calculated, which can provide a reference for the fracturing treatment of this gas field.