含水层地下储气库注采模拟及安全可靠性研究

发布时间：2018-01-16 16:02

本文关键词：含水层地下储气库注采模拟及安全可靠性研究　出处：《中国石油大学(华东)》2015年博士论文　论文类型：学位论文

【摘要】：含水层改建储气库具有渗透率高、水力传导性好、储量大、成本低的优点,由于其高渗透率的特点能够显著提高储气库注气、采气速率,国际上含水层储气库在天然气储存上的应用仅次于衰竭油气藏储气库,而目前我国还没有含水层储气库投入生产和运用。储气库运行过程中的注采问题及安全问题一直是储气库研究的热门,因此对含水层储气库注采分析以及管柱、盖层的安全可靠性研究是储气库研究的关键,拟利用测井试井信息、地应力场资料,通过分形渗流模型、可靠度模型等得到可以预测储层压力及管柱、盖层可靠度的方法,实现含水层储气库注采模拟,建立含水层储气库安全可靠性预测模型。具体研究工作及得到的结论如下:(1)将储气库渗流分析分为两种介质进行:一是裂隙介质;二是孔隙介质。考虑储气库裂隙介质分形特点以及临界运移含水饱和度的影响,根据两相不稳定渗流理论和分形理论,建立储层相对渗透率与裂隙尺寸、典型单元体尺寸、毛管压力之间的关系,并分析含水层储气库的渗流规律及井底压力变化规律;考虑储气库储层孔隙介质分形的特点以及储层压力变化对储层介质渗流参数的影响,根据气体不稳定渗流理论,建立了含水层储气库储层压力动态分布的分形渗流模型。分析结果表明:裂隙介质中储气库井底压力随着裂隙介质分形维数、储层厚度、排水速率的增大而减小,随着典型单元体尺寸、裂隙尺寸比、注气速率的增大而增大;孔隙介质中储气库的储层压力随着储层介质弯曲率、气体粘度、注气速率、注气时间的增大而增大,随着分形维数和储层厚度的增大而减小;分形维数、储层厚度、注气速率、注气时间对储气库储层压力的影响比较显著,而介质弯曲率和气体粘度对其影响不明显。(2)考虑岩体参数不确定性对不活动断层破坏的影响,利用测井资料及区间理论得到注气后断层危险系数的置信区间,根据断层危险系数置信区间得出储气库断层稳定的最大运行压力;利用该方法对国内某含水层储气库断层危险系数置信区间及最大运行压力进行分析,分析结果表明随着断层倾角的增大,断层危险系数先增大后减小,当断层倾角?与岩石内摩擦角?的关系为(10)?(28)??/245时,此时的断层危险系数最大,断层最易破坏;考虑参数不确定性运用区间理论计算所得到的储气库最大运行压力比未考虑参数不确定性所得到的结果要小,因此为保证储气库安全运行,可选取最大运行压力置信区间的下限作为储气库最大运行压力。(3)根据断层剪切破坏的特点建立断层滑移极限状态函数,将凸集模型引入储气库断层滑移非概率可靠度预测,并在断层滑移可靠度计算过程中对极限状态函数进行线性近似,该模型在求解断层滑移可靠度时不需要大量的参数样本和固定的概率分布函数,具有较好的实用性。利用上述方法对国内某储气库注气后不活动断层的可靠性进行了分析研究,将本文方法计算结果与Monte-Carlo方法计算结果进行了对比,本文所得到的可靠度结果可满足工程计算精度要求;断层滑移可靠度随着断层位置孔隙压力、地应力不均匀系数的增大而减小,随着断层倾角?的增大先减小后增大,并且当断层倾角?与岩石内摩擦角?的关系为[(10)?(10)?????/2)45max(/2),45min(]时,此时断层的滑移可靠度最小。(4)根据区间理论及非概率可靠性理论,利用测井资料和岩体破坏准则得到了盖层岩体参数的置信区间,给出了不同破坏准则下盖层的安全系数置信区间及可靠性指标计算公式,用上述方法对某储气库盖层的安全系数置信区间及可靠性指标进行了预测。分析结果表明:利用Hoek-Brown破坏准则和Mohr-Coulomb破坏准则计算所得安全系数最小置信区间分别为[1.715,1.458]、[2.037,1.706],最小可靠性指标分别为-3.213、-0.777;Hoek-Brown破坏准则计算所得到的可靠性指标是偏于安全的;非概率可靠性与传统的概率可靠性分析方法相比,不需要确定的岩体参数分布,尽可能的减少了对岩体样本数据量的要求,更有利于实际储气库盖层可靠性的预测。(5)考虑储气库套管在服役过程做壁厚变薄、外径变大的特点,将储气库套管的剩余强度分别采用几种不同的方法进行分析,在剩余抗内压强度分析中引入了基于内径尺寸的储气库套管剩余抗内压强度计算公式,并对国内某储气库服役套管的剩余强度和剩余寿命进行了分析。利用改进的套管抗内压强度公式与传统的计算公式进行了对比,改进的公式计算结果可以满足实际工程的需求,在工程上得到了很好的应用,为储气库套管剩余强度的分析提供了一种新的方法。
[Abstract]:Aquifer gas storage reconstruction has high permeability, hydraulic conductivity, large reserves, low cost advantages, because of its high permeability characteristics can significantly improve the gas storage, gas injection, gas production rate, the application of aquifer gas storage in natural gas storage after the failure of oil and gas reservoir gas storage, but at present in our country no aquifer gas storage is put into production and use. Problems and security problems in the operation process of gas storage injection gas storage has been a hot research, so the analysis and column mining on aquifer gas storage, safety cover is the key research of gas storage research, intends to use the logging test information. The stress field data, the fractal percolation model, reliability model can predict reservoir pressure and column cover layer reliability method, to achieve simulation of injection gas storage aquifer, the establishment of aquifer gas storage safety The prediction model. The main research works and conclusions are as follows: (1) the analysis of reservoir seepage is divided into two types: one is the medium pore fissure medium; two gas storage medium. Considering the fracture medium fractal characteristics and influence of critical migration saturation, according to two-phase unsteady seepage theory and fractal theory, storage relative permeability and crack size of layer, typical element size, the relationship between capillary pressure, and the analysis of the seepage flow and bottom pressure variation of aquifer gas storage; considering the characteristics of gas storage reservoir porous media fractal and influence of reservoir pressure on reservoir seepage parameters, according to the unsteady gas seepage flow the theory, established the aquifer gas storage reservoir dynamic pressure distribution fractal percolation model. Analysis results show that the gas storage pressure in fractured medium with the fractal dimension of fractured medium, storage The thickness, increase the drainage rate decreases, with the typical element size, crack size ratio, increasing gas injection rate increases; the reservoir pressure reservoir pore medium reservoir reservoir with medium bending rate, gas viscosity, gas injection rate increases, the gas injection time increases, decreases with the increase of fractal the dimension and thickness of the reservoir; fractal dimension, reservoir thickness, gas injection rate and gas injection time had significant effects on gas storage reservoir pressure, while the medium bending rate and gas viscosity on the effect is not obvious. (2) considering the uncertainty of parameters of rock mass damage on the inactive faults, using confidence interval logging data and interval theory of gas injection after fault risk factors, according to the fault risk coefficient of confidence interval and obtained the maximum operating pressure of gas storage stable fault; confidence level risk coefficient of a domestic aquifer gas storage by using this method Analysis of the range and the maximum operating pressure and the analysis results show that the increase of the inclination angle of the fault, the fault risk coefficient increases first and then decreases, when the dip angle and internal friction angle of rock?? the relationship (10) (28)??? /245, the biggest risk coefficient of fault, fault most easily damaged; consider the results the parameter uncertainty using the interval analysis of gas storage in the maximum operating pressure has been calculated than without considering the parameter uncertainties are smaller, so as to ensure the safety of gas storage operation, the lower limit can select the maximum operating pressure of the confidence interval for the maximum operating pressure of gas storage. (3) to establish the limit state function according to the characteristics of fault slip fault shear failure, the convex model into storage fault slip non probabilistic reliability prediction, and the limit state function in fault slip reliability calculation process of linear approximation, the model for solving fault Layer slip reliability without large sample parameters and fixed probability distribution function, has better practicability. By using the method of reliability of a domestic gas storage injection after faults are analyzed, the method calculation results and Monte-Carlo calculation results are compared, the reliability of the results we can meet the requirements of Engineering calculationprecisionand; fault slip reliability with fault location of pore pressure, increase the stress uniformity coefficient decreases with the increase of the inclination angle of the fault? And when the first decreases and then increases, the fault dip and internal friction angle of rock?? the relationship [(10) (10)?????? /2) 45MAX (/2), 45min (], the reliability of the minimum slip fault. (4) according to the interval theory and non probabilistic reliability theory, logging data and rock failure criteria was obtained using confidence cover parameters of rock mass , the formula of interval reliability index and safety factor of caprock are given different failure criteria under confidence, were predicted using the method of safety coefficient of a gas storage layer and caps the confidence interval of reliability index. Analysis results show that using the Hoek-Brown failure criterion and Mohr-Coulomb criterion to calculate the safety factor of the minimum confidence interval was [1.715,1.458] [2.037,1.706], the minimum reliability index were -3.213, -0.777; Hoek-Brown failure criterion reliability index calculated is safe; compared to non probabilistic reliability probabilistic reliability and the traditional analysis method, does not need to determine the parameters of rock mass distribution, as much as possible to reduce the amount of rock sample data requirements, more conducive to the actual gas caps layer reliability prediction. (5) considering the gas storage casing in the service process of the thin wall thickness, the outer diameter becomes larger. The residual strength, the gas storage casing respectively by several different methods of analysis, the residual compressive strength within the analysis was introduced in the gas storage casing diameter residual strength calculation formula of internal pressure on remaining strength and life and service of a domestic gas storage casing is analyzed. Compared by using the improved casing internal pressure strength formula with the traditional formula, the improved formula calculation results can satisfy the practical requirements of engineering, is widely used in engineering, provides a new method for the analysis of gas storage casing residual strength.

【学位授予单位】：中国石油大学(华东)
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TE972.2

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