致密砂岩气藏数值模拟方法研究——以鄂尔多斯盆地大牛地气田太2段气藏为例  

Numerical simulation technique for tight sandstone gas reservoirs:Examples from Taiyuan 2 gas reservoirs,Daniudi gasfield,Ordos Basin

作　　者：张凌筱 任广磊[1] 孙华超 姜超 杨文娟[1] 申进 张伟杰[1] ZHANG Lingxiao;REN Guanglei;SUN Huachao;JIANG Chao;YANG Wenjuan;SHEN Jin;ZHANG Weijie(Sinopec North China Company,Zhengzhou,Henan 450006,China)

机构地区：[1]中国石化华北油气分公司,河南郑州450006

出　　处：《天然气技术与经济》2023年第5期1-8,52,共9页Natural Gas Technology and Economy

摘　　要：数值模拟技术是目前剩余气定量表征、气藏调整方案优化和产量预测的主要手段之一。然而,致密砂岩气藏复杂的储层地质条件和渗流特征,使得在采用常规数值模拟技术时难以准确描述剩余气的分布规律。为了实现对致密砂岩储层剩余气的精细定量表征,以鄂尔多斯盆地大牛地气田太2段气藏为研究对象,分析了不同渗流特征因素对产量的影响,同时基于致密砂岩气藏渗流理论,结合气藏工程和室内实验分析研究,建立了启动压力梯度、水锁伤害、应力敏感等在数值模拟中的等效表征方法。研究结果表明:①随着该区气藏开发的进行,地层压力降低和外来液气的侵入,岩石储层产生的应力敏感效应和水锁伤害会降低储层的有效渗透率,严重影响气井产能;②随着地层水和外来液体的侵入,气井在生产中会出现储层水锁伤害,利用相渗水平端点标定实现束缚水变可动水模拟,垂直端点标定实现生产初期水锁气相渗流伤害模拟,进一步在模型Schedule模块中通过对不同阶段相渗曲线调用,解决了气井中后期压力拟合偏差大的问题;③在数值模拟中考虑了启动压力梯度等因素的等效表征后,模型历史拟合符合率由之前的45%提高至85%,计算结果更加符合矿场的实际情况。结论认为,该研究成果完善了致密砂岩气藏渗流理论和数值模拟方法,对同类型油气藏的高效开发具有理论指导和实践意义。Numerical simulation is one of critical techniques for the quantitative characterization on remaining gas,scheme optimization of reservoir adjustment,and production prediction.For tight sandstone gas reservoirs,however,their complex geological conditions and flow behaviors make the accurate description of remaining-oil distribution impossible by using conventional simulation techniques.Thus,for fine characterization of remaining gas in tight sandstone reservoirs,Taiyuan 2 gas reservoirs of Daniudi gasfield in Ordos Basin were taken as examples to explore the effect of flow behaviors on production.Moreover,coupling with reservoir engineering and laboratory experiments,the equivalent characterization on start-up pressure gradient,water-locking effect and stress sensitivity was conducted in numerical simulation according to seepage theories in tight sandstone reservoirs.Results show that(i)due to both formation-pressure drop and another fluid or gas invasion after reservoir development,there induced stress sensitivity effect and water-locking damage in reservoir rocks,causing the decrease of effective permeability to severely restrict productivity;(ii)as the invasion of formation water and another fluid,the locking damage may also occur.Changes of irreducible to movable water are simulated by horizontal endpoint calibration of relative permeability,and the damage to gas flow in the early stage of production is simulated through vertical endpoint calibration.Furthermore,relative-permeability curves at different stages are mobilized in module of Schedule model.Large deviation in pressure matching can be avoided during the middle to late stage of production;and(iii)when the equivalent characterization on the start-up pressure gradient is considered in numerical simulation,the model's coincidence in the process of history matching increases to 85%from 45%,indicating this finding more in line with in-situ conditions.In conclusion,these results may perfect seepage theories and numerical simulation technique in tight sands

关 键 词：鄂尔多斯盆地 大牛地气田 致密砂岩气藏 数值模拟 启动压力梯度 水锁效应 应力敏感 

分 类 号：TE37[石油与天然气工程—油气田开发工程]