储气库注采井井筒温度场预测与影响因素分析

随着冬季对天然气需求的持续增加,对储气库的调峰能力提出了严峻的考验,注采井作为连接地面与地下的通道,井筒温度受注采周期的影响发生变化,如何准确的预测井筒内温度变化,对于预测环空压力、保证油管和套管安全、水泥环密封性和储气库运行安全至关重要。本文根据流体力学中质量守恒定律、能量守恒定律和动量定理,将气体的压强、温度、密度和流速进行耦合分析,利用显式四阶Runge-Kutta数值求解方法,输出油管内气体不同深度的流动参数,并对影响油管内气体温度的敏感性因素进行分析,得到了储气库注气过程、采气过程、关井阶段温度分布规律。结果表明注气过程井底处温度受注气量影响较大,注气时间和注气压力对井底温度影响较小；在采气过程,井口处气体温度随采气量的增加而增大,油管内气体压力由井底到井口逐渐减小,并且随着采气量的增加,减小趋势越明显；在关井初期,油管内气体温度变化速率较大,随着关井时间的持续增加,油管内气体温度逐渐趋于地层温度,并且越接近于井口气体温度变化速率越明显。

WellboreTemperature Field Prediction and Influencing Factors Analysis of Gas Storage Injection Production Wells

With the continuous increase of natural gas demand in winter, the peak-shaving capacity of gas storage is put forward a severe test. As a channel connecting ground and underground, wellbore temperature changes under the influence of injection and production cycle. How to accurately predict wellbore temperature changes is very important to predict annulus pressure, ensure the safety of tubing and casing, cement ring sealing and gas storage operation safety. According to the law of mass conservation, energy conservation and momentum theorem in fluid mechanics, the pressure, temperature, density and velocity of fluid are coupled. By using the explicit fourth order Runge-Kutta numerical solution method, the flow Parameters of different depth of fluid in tubing are outputted, and the sensitivity factors affecting gas temperature in tubing are analyzed. The results show that the temperature at the bottom of the well is greatly affected by the gas injection, and the gas injection time and pressure have little effect on the bottom of the well; In the process of gas production, the gas temperature at the wellhead increases with the increase of gas production, the gas pressure in the tubing decreases gradually from the bottom to the wellhead, and the decrease trend becomes more obvious with the increase of gas production; In the early stage of shut-off, the gas temperature in the tubing changes at a large rate. With the continuous increase of shut-off time, the gas temperature in the tubing gradually recovers to the formation temperature, and the closer it is to the wellhead gas temperature change rate, the more obvious it is.