临兴致密气藏压裂水锁伤害评价与措施优化

Assessment of Water Block Damage during Fracturing of Tight Gas Reservoir in Linxing Area and Optimization of Relevant Countermeasures

针对临兴致密气水锁伤害问题,利用水相圈闭指数法和总水体积法,对该地区压裂层位进行水锁伤害评价。采用考虑启动压力的理论模型计算出液氮用量的理论值,分析了液氮用量与压裂后产能之间的关系,从而对水锁解除措施进行优化。研究结果表明:临兴地区较多层位存在水锁风险;对于易水锁、临界水锁层位,充足的液氮量有利于解除水锁,建议临兴地区液氮用量经验系数取4.0~5.0。该研究可为临兴致密气压裂水锁解除措施优化提供依据。

With consideration to problems related to water block damage in Linxing tight gas reservoirs,water phase trapping index method and total water volume method have been used for assessment over water block damage in layers with fracturing operations in the study area. By using the theoretical model with consideration to the start-up pressure,theoretical volume of quantity of liquid nitrogen can be determined. In addition,correlation between quantity of liquid nitrogen and post-fracturing productivity has been determined. In this way,proper measures for removal of water blocking can be optimized. Research results show： multiple layers within the Linxing Area may involve water blocking risks; Sufficient quantity of liquid nitrogen shall be deployed in layers susceptible to water blocking or critical water blocking to minimize impacts of such water blocking. It was proposed to use 4. 0-5. 0 as empirical coefficients for quantity of liquid nitrogen in the Linxing Area. Relevant researches may provide reliable foundation for researches related to optimization of suitable measures for removal of water blocking during fracturing of tight gas reservoirs in the Linxing Area.