低渗气藏气井产量递减分析及预测方法研究

发布时间：2018-02-04 19:34

本文关键词： 低渗透产量递减影响因素递减类型递减模型　出处：《西南石油大学》2017年硕士论文　论文类型：学位论文

【摘要】：低渗气藏递减规律对气藏的动态预测和生产规划工作具有重大意义,针对低渗气藏气井产量递减存在递减类型判识不准确导致递减规律认识不清等问题,本文从传统Arps递减类型判识、递减率及影响因素和产气量变化3个方面开展了以下研究:首先是递减类型判识方法研究。针对传统Arps方法通过线性相关系数来判定递减类型造成气井递减类型判识难度大,提出以现代产量不稳定分析法评价动储量为标准,通过对比不同递减类型下气井技术可采储量来优选递减类型;另从Arps双曲递减通式出发,推导并绘制了不同n值情况下无因次递减率和采出程度的图版,图版法可快速获得n的值,实例表明图版法与不稳定分析动储量评价法结果基本一致。然后是递减率影响因素研究。气井递减率随生产时间不断变化,且与储层、工作制度等有关,建立典型低渗气井单井数值模型,运用单因素分析法,研究递减率变化规律及其主要影响因素。结果表明,气井递减率呈快速和缓慢递减两个阶段,气井进入递减期2～3年后递减率趋于稳定;递减率随着渗透率、含气饱和度、井口压力的增加而增加,随孔隙度、井控储量的增加而减小;生产后期递减率不随储层厚度、初期配产、地层压力变化而改变。采用正交试验设计方法,确定出井控储量和渗透率为影响低渗气井产量递减的主控因素。其次是递减率模型的建立。针对井控储量、渗透率、地层压力和配产气量等4个主要影响因素,运用响应曲面设计,回归递减率与各因子非线性模型,以快速准确地预测出递减率,且能够避免传统Arps方法递减类型的判识。根据预测模型,井控储量越大,渗透率越小,递减率越小。为降低气井生产过程中产量递减率,建议综合考虑各参数对递减率的影响,尽量提高气井的井控储量。最后是产气量递减模型研究。直接从低渗透气井产量递减曲线的特征入手,改进了幂律产量递减模型,使其物理意义明确,国内外实例气井表明,改进模型比幂律模型拟合精度更高;针对递减指数在递减过程中不断变化,推导了新的产量递减分析模型,实例分析证明新模型对低渗致密气藏产量递减分析具有很好的适用性。
[Abstract]:The decline law of low permeability gas reservoir is of great significance to the performance prediction and production planning of gas reservoir. This paper is based on the traditional Arps decline type. The following studies have been carried out in the following three aspects: decline rate and influencing factors and change of gas production:. The traditional Arps method is difficult to identify the decline type of gas wells by linear correlation coefficient. It is put forward that dynamic reserves can be evaluated by modern production instability analysis method, and the decline type can be selected by comparing the recoverable reserves of gas wells under different decline types. In addition, based on the general formula of Arps hyperbolic decline, the dimensionless decline rate and the extraction degree are derived and plotted under different n values. The chart method can get n value quickly. Examples show that the results of chart plate method and unstable analysis dynamic reserve evaluation method are basically consistent. Then there is a study on the influencing factors of decline rate. The decline rate of gas wells changes with production time and is related to reservoir and working system. The numerical model of single well in typical low permeability gas well is established. The variation law of decline rate and its main influencing factors are studied by single factor analysis. The results show that the decline rate of gas well is in two stages of rapid and slow decline. The decline rate of gas wells tends to be stable after entering the decline period of 2 ~ 3 years. The decline rate increases with the increase of permeability, gas saturation and wellhead pressure, and decreases with the increase of porosity and well control reserves. The decline rate of late production does not change with reservoir thickness, initial production and formation pressure. The orthogonal design method is used. It is determined that the well controlled reserves and permeability are the main factors influencing the production decline of low permeability gas wells, and the second is the establishment of decline rate model, aiming at the four main influencing factors: well controlled reserves, permeability, formation pressure and gas production. By using response surface design, regression decline rate and nonlinear model of each factor, the decline rate can be predicted quickly and accurately, and the recognition of decline type of traditional Arps method can be avoided. The larger the well control reserves, the smaller the permeability, and the smaller the decline rate. In order to reduce the production decline rate in the production process of gas wells, it is suggested that the influence of various parameters on the decline rate should be considered synthetically. Finally, the gas production decline model is studied. Starting with the characteristics of the production decline curve of low permeability gas wells, the power law production decline model is improved to make its physical significance clear. Examples at home and abroad show that the improved model is more accurate than the power law model. In view of the continuous change of decline index in the process of decline, a new model of production decline analysis is derived. The case study shows that the new model is suitable for the analysis of production decline in low permeability tight gas reservoirs.
【学位授予单位】：西南石油大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TE328

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