X储气库注气过程中断层安全性分析

发布时间：2018-03-21 04:17

本文选题：储气库　切入点：断层　出处：《西南石油大学》2017年硕士论文　论文类型：学位论文

【摘要】：枯竭气藏型储气库是目前世界上使用最广泛的地下储气库,储气库强注强采的特征可能使注气末期地层压力迅速上升而破坏断层密封性,进而造成天然气泄漏事故,为避免此事故发生对储气库运行中断层安全性进行分析。本文开展了如下研究:断层失稳分析。储气库注气末期地层压力不断升高有可能克服断层面正应力和内聚力导致断层开启,或者是在地层压力和断层岩石受到的三个主应力的共同作用下使断层岩石破裂,两者都可能导致天然气泄漏。通过计算导致断层开启或断层岩破裂的地层压力,对比两者压力大小,选用小者作为储气库运行中断层处地层压力允许上限值,运行中断层处地层压力不超过此值才能保证断层安全。断层处地层压力变化规律研究。储气库运行中有多口井同时注气,需要获取断层处最大地层压力出现的位置和压力值。本文利用已经成熟的井底压力和地层压力计算公式计算从井口到井底的压力、再计算断层处的地层压力,并对井底压力计算精度的提高做出探索。利用压降叠加的原理获得单井和多井注气模式下断层处地层压力分布公式,并以此为基础分析储气库注气过程中断层处地层压力的分布规律。断层处地层压力影响因素分析。对影响断层处地层压力变化的7个因素进行单因素分析,得出不同影响因素条件下断层处最大地层压力变化规律。用灰色系统理论中的关联度分析法得到各影响因素对断层处最大地层压力的影响程度,影响程度由大到小为:注气速度、储层厚度、渗透率、孔隙度、井距、注采井到断层距离、运行井数,用上述排序来找出关键影响因素,将这些关键影响因素做为绘制图版的变量。图版的绘制与分析。为保证运行中断层安全性,以断层处最大地层压力允许上限值为界限,合理控制运行参数。以X储气库的实际情况为基础绘制图版,通过绘制图版的方法得出运行井数、单井注气量、气井与断层垂直距离和断层处最大地层压力之间的关系。确定运行井数、单井注气量、气井与断层垂直距离中的任意两个参数值,可合理选择另一个参数的取值,避免在储气库运行中因为盲目使用不当的运行措施使断层密封性遭到破坏。在给出的断层处最大地层压力允许上限值发生改变时;当存在井底污染或者实施增产措施而使注气能力发生改变时;当增加新井而改变井到断层的垂直距离时;运行井数改变时都可以通过查询图版确定保证断层安全的合理运行措施。运用图版还可以在储气库运行过程中快速判断当前的运行措施是否会达到上限压力,以便及时做出调整来保证断层安全性。本文研究通过绘制图版提供了一种保证X储气库运行中断层安全的合理运行措施选择方法,为X储气库安全运行提供参考。
[Abstract]:The depleted gas reservoir is the most widely used underground gas storage in the world at present. The characteristics of strong injection and strong production of gas storage may cause the formation pressure to rise rapidly at the end of gas injection and destroy the fault seal, which will lead to the gas leakage accident. In order to avoid this accident, the fault safety in the operation of gas storage reservoir is analyzed. The following studies have been carried out in this paper: analysis of fault instability. Increasing formation pressure at the end of gas injection in reservoir may overcome normal stress and internal stress of fault plane. Accumulation causes the fault to open, Or it is the combination of formation pressure and the three principal stresses on the fault rock that makes the fault rock rupture, both of which can lead to natural gas leakage. By calculating the formation pressure that caused the fault to open or the fault rock to break, Comparing the size of the two pressures, the small one is chosen as the upper limit of the formation pressure allowed at the fault in the operation of the gas storage reservoir. In order to ensure fault safety, the formation pressure in running fault can not exceed this value. The variation of formation pressure in fault area is studied. There are many wells to inject gas at the same time in the operation of gas storage. It is necessary to obtain the position and pressure value of the maximum formation pressure at the fault. In this paper, the pressure from the well head to the bottom hole is calculated by using the mature formula for calculating the bottom hole pressure and the formation pressure at the fault, and then the formation pressure at the fault is calculated. Based on the principle of pressure drop superposition, the formula of formation pressure distribution at fault in single well and multi-well gas injection mode is obtained. On this basis, the distribution law of formation pressure at fault during gas injection in gas storage reservoir is analyzed, and the influencing factors of formation pressure at fault are analyzed. The single factor analysis of seven factors affecting formation pressure change at fault is carried out. The variation law of maximum formation pressure at fault is obtained under different influence factors, and the degree of influence of each factor on maximum formation pressure at fault is obtained by using the correlation degree analysis method of grey system theory. The influence degree from large to small is: gas injection velocity, reservoir thickness, permeability, porosity, well spacing, injection-production well to fault distance, number of operating wells. These key factors are taken as variables for drawing the plate. The drawing and analysis of the plate. In order to ensure the safety of the fault in operation, the upper limit value of the maximum formation pressure allowed at the fault is taken as the limit. Based on the actual situation of X gas storage depot, drawing chart plate, through drawing chart plate method, the number of operating wells and gas injection rate of single well can be obtained. The relationship between gas well and vertical distance of fault and maximum formation pressure at fault. Determining the number of running wells, gas injection rate of single well and any two parameter values in vertical distance between gas well and fault can reasonably select the value of the other parameter. Avoid failure of fault sealing due to improper operation measures in the operation of gas storage reservoir. When the maximum allowable upper limit value of formation pressure is changed at the given fault; When the bottom hole is polluted or the gas injection capacity is changed by the measures of increasing production, the vertical distance between the well and the fault is changed by adding new well. When the number of operation wells is changed, the reasonable operation measures to ensure fault safety can be determined by querying the chart plate. The chart can also be used to quickly judge whether the current operation measures will reach the upper limit pressure during the operation of the gas storage. In order to make timely adjustment to ensure fault safety, this paper provides a reasonable operation method to ensure the safety of X gas storage by drawing a chart, and provides a reference for the safe operation of X gas storage.
【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】：TE88

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