气藏开采中地层温度及井口压力对井筒流动参数的影响

EFFECT OF FORMATION TEMPERATURE AND WELL-HEAD PRESSURE ON GAS FLOW ALONG WELL-BORE IN GAS PRODUCTION

根据气藏开采过程中气体在井筒内流动的特点 ,得出了单相气体恒速流动状态微分方程组。阐述了不同地层温度与井口压力下井筒气体流动参数的分布 ,并说明了不同地层温度下 ,井口回压对井底流压与产量的影响。结果表明 ,在不同的地层温度与井口压力下 ,井筒底部的气体速度与密度可以高于、等于或低于井筒上部的气体。通过合理控制井口压力可以调整井筒内流体流动状态参数 ,从而合理控制生产压差和产气量 ,以满足气井安全测试与生产的要求。对几口井数据的数值模拟结果验证了地层温度与井口压力对井筒气体流动参数的影响规律。

A differential equation system for constant-velocity flowing state of single-phase gas was obtained according to characteristics of gas flowing in gas well bore. The distributions of flowing parameters in well bore at different formation temperature and varying tubing-head pressure were discussed. The effects of well-head back pressure on flowing bottom hole pressure and gas flow rate were analyzed. It is demonstrated that flow velocity of gas and density of gas at well bottom may be higher, equal to or even lower than those at well head while adopting different combinations of formation temperature with well-head pressure. Different formation temperature and varying well-head pressure have influences on the variation of bottom-hole pressure and gas flow rate. So reasonable control of well-head pressure can improve gas flowing characters in well bore to assure the safety of high-pressure well in the process of test and production. Several calculation cases proved the flow rules of gas resulted from formation pressure and well-head pressure.