凝析气藏循环注气动态分析理论及应用

【作者】 熊钰；

【导师】 张烈辉；

【作者基本信息】 西南石油大学 ， 油气田开发工程， 2018， 博士

【摘要】 在全球已发现的凝析油气田(藏)超过12200多个,由于技术条件及供气需求等原因,部分高含凝析油的凝析气藏多采用衰竭式开发,从资料统计来看,目前国内外凝析气藏的开发效果大都不是很理想,如我国最早正式投入开发的板Ⅱ凝析气藏废弃时天然气、凝析油和底原油的采出程度分别为48.9%、37.21%。天然气、凝析油、原油的采出程度均较低。我国牙哈凝析气田复杂程度更高,高温、高压、高含凝析油、高含蜡,对气藏埋藏深、达到5000m,地层压力高,地面回注压力超过60MPa,凝析油储量达到2300万吨,天然气储量达到250亿方。规模如此之大的凝析气田采取高压循环注气开发在国内是首开先例,在国际上也寥寥可数。与此类型气田开发相对应的高压循环注气气藏工程理论,国外起步略早,但也是在摸索中研究分析理论,特别是气藏动态分析方法和开发效果评价及开发水平分级评价方面均没有系统的进行过研究。国内牙哈凝析气田从2000年开始大规模循环注气保压开采,经过十七年开发实践,通过产学研结合研究,特别是塔里木检测到回注干气的超覆气窜对完善循环注气下的渗流理论和指导类似气田的高效开发提供了新的研究基础。本文主要为在2006-2012年间承担的塔里木凝析气田《凝析气田循环注气开发动态评价方法研究》项目和相关项目的研究成果和持续跟踪研究基础上写成的,2012年-2018年的持续性跟踪研究是在没有项目支持下自行进行的,在资料上得到了塔里木相关负责同志的支持,上并取得了以下5个方面的创新性认识和观点成果:(1)高含凝析油的凝析气藏循环注气过程中,基于二元体系的“气-气”平衡,提出注入干气和原地凝析气之间存在“微界面现象”假说,把注入干气运动归纳为驱替作用和扩散混合作用。扩散混合作用含重力分异和热梯度的影响及组分梯度,“微界面现象”和组分梯度共同形成了注入气的宏观超覆运动,导致注入干气的向气藏顶部聚集,使气窜并不遵循按高渗条带气窜的规律。(2)建立了高温高压环境下的气液两相界面张力新公式,完善了适合深层高温高压环境下的气井井筒动态描述方法和凝析气井井底压力精确计算方法,使井底压力的预测和计算精度提高到0.5%。(3)应用泰勒级数展开方法、证明了凝析气井反凝析污染对井底压力的影响表达方法,并用阻塞表皮系数概念建立了产能测试曲线异常的修正方法。建立了基于凝析油气分相拟压力的生产动态拟合产能评价方法,所给出的近井带反凝析饱和度变化显示该方法是合理的。(4)进一步用实际动态数据验证所建立的含有回注比循环注气压降储量的正确性,并从物质平衡方程通式和注采差异法多途径证明了考虑水侵动态影响的循环注气物质平衡方程通用形式。采用函数对比法证明和实践验证证明了水体影响函数形式的统一性。(5)基于“微界面现象”假设,建立了标准通用图版和采收率标定方法,并给出了图版系数确定的基本原理和方法;建立了一套凝析气藏循环注气开发效果评价方法体系和凝析气藏循环注气开发水平评价分级指标体系;这些在持续跟踪研究中显示具有明显的通用性理论特点。更多还原

【Abstract】 More than 12200 gas-condensate reservoirs have been discovered in the word.They are mainly locate in Anmerica,Russia,Austrilia states etc.Depletion development is the first choice for most of all oil and gas company by some reason of technique or gas supplying.The performance and recovery of main gas-condensate reservoirs shows they are not satisfy though statistical results.Condensate oil and gas recovery are much lower than our hope for it even through gas recycling.Yaha gas-condensate reservoir is a biggest high condensate yerld in our contry.Its pressure is more than 55 MPa ant its temperature is higher than 130℃.Formation depth is exceeding 5000 miters.The OGIP of Yaha gas-condensate reservoir is 23 millions ton and gas reserve is 23 billions cubic meter.We have not produced the kinds of gas-condensate reservoir before by gas-recycling.All of therotical methods and techniques for gas reservoir eneering have not been systemly compeleted in literatures,books and papers in the word especily in performance evaluation and development level classification.Yaha have been producted by gas-recycling since 2000.Dry gas which has been reinjected in reservoir is not mixed in insitu condensate gas.Its flowing law has been discovered firstly during recycled gas break through control operations show that is governed by gravity segregation.Best on the new dectect,five new achievements has been presented in this thesis.(1)Reinjected gas is governed by gravity segregation and microinterface phenomena between reinjected gas and local condensate gas.Light component will flow up to high location by compostional grading effection in the distance from injection well to prodcuce well.Thief zone of dry gas break through is contributed to gravity segregation,not by high permeability.(2)A new gas-water interfacial tensions correlation has set up here by using nonlinear regression.And a modified flowing pressure prediction way for produce well has been used to calculate Yaha realistical production wells borehole pressure.Results show we can obtain 0.5 percentage precision.(3)The influence of retrograde condensate on production test has been proofed by using Taler series function.It can be used to adjust abnormal curve of deliverability test to be correctly.A new way of getting well deliverability through fitting production data also has been present here.It based on condesate oil and dry gas pseudopressure repectively.Application shows that it is a reasonable method when the well did not do well deliverability test.(4)The general formula of mass balance under gas-condensate recycling with water invasion has been deduced in thesis and been validate with production data.General AIF forms has also been proofed with functional contrast method and application.Three methods for handling irregular deliverability test data and two recovery predicting ways for condensation oil and dry gas have also been build in the thesis.Prictise in Yaha field shows that they are much more practicality。Chart way for anlysis reinjected gas breaking through has also been gived here.It can be used to subdivision for injection gas and instu gas.And,it also makes right calculating dynamical reserve become probably and exacting evaluates water influx.(5)Based on assumption of"Microinterface Phenomena",a series ways of retrograde oil recovery calibration and normal chart of performance evaluation have presented in thesis.Application shows that all of them are correct and universal for evaluating gas recycling performance。更多还原