储气库干化盐析效应量化表征及干化扩展范围预测方法

The quantitative characterization of dry-out and salt precipitation effects and its extended-distance predicting method in gas storage

秦正山 何勇明 鲁洪江 刘逸盛 谢晶 孙双双 李柏宏

成都理工大学能源学院，四川 成都 610000 中国石化西南油气分公司采气四厂，重庆 402160 中国石油长庆油田分公司采油六厂，陕西 西安 710000

储气库注采过程中存在近井地带干化盐析的问题，不仅影响储气库的注采能力，甚至影响储气库稳定运行及运行年限。文中基于BL经典分流理论及气水渗流规律，建立了储气库干化盐析效应量化表征数学模型及盐堵损伤量化评估方法，解决了储气库干化问题关键参数的量化表征及干化扩展范围的预测难题。研究结果表明：理论推导的盐饱和度、盐析出量是评估储层盐堵的重要表征参数，与储层温压条件、流体性质及气水相对渗透率等有密切的关系；储气库注采循环过程会导致干化扩展范围逐渐由近井向远井发展，仅依靠注入端短时间注水来解除近井堵塞，可能无法有效恢复地层孔隙度、渗透率及天然气注采能力；基于文中建立的数学模型得到的研究结论与前人实验研究结论具有较好的一致性。文中研究成果不仅具有较好的现场应用价值，而且对干化盐析现象的理论研究以及干化盐析机理的认识具有指导意义。

Dry-out and salt precipitation problems in gas storage not only affect gas injectivity and productivity, but also affect the stability and longevity of the storage system. Based on Buckley-Leverete fractional flow theory and gas-water percolation law, a mathematical model of the quantitative characterization of dry-out and salt precipitation effects and quantitative assessment method of salt plugging damage in gas storage are developed, which address the challenges of quantitative characterization of key parameters and extended-distance prediction of dry-out. The research results show that the theoretically derived salt saturation and salt precipitation mass are important parameters for assessing salt plugging damage, which have very close relationship with temperature-pressure condition, fluid property and gas-water relative permeability. It is expected that the injection and production cycle in gas storage will result in a gradual extension of the range of dry-out from nearest wells to farthest wells. To unblock the salt plugging damage by means of water injection at the injection side during a short period may not be able to effectively restore the porosity, permeability, gas injectivity and productivity. The conclusions based on the model developed in this paper are consistent with those reached by previous experimental studies. The research results not only have significant practical value for field application, but also have guiding significance for theoretical studies and the mechanism understanding of the dry-out and salt precipitation.

10.6056/dkyqt202303022