水平井筒气水流动规律及影响因素

由于流动方向变化及壁面流体的不断径向入流,水平井筒的气水流动规律与常规直井存在较大差异。在总结前人研究结果的基础上,优选水平井筒气液两相预测模型,并在验证模型可靠的情况下,考虑管壁入流和气液流型变化,改变气量、水量、管径、倾角、轨迹波动、气水入流位置等多个影响因素,对水平段流型、压力分布规律及影响因素进行综合预测分析,为水平气井的生产管理及后期措施优化提供依据。研究结果表明,一般生产条件下水平井筒存在分层流、间歇流和环雾流3种流型,管径和倾角对水平井筒的气、水流型影响最为明显,管壁入流对入流就地井筒流态的影响较小。水平井筒压力损失与气量、水量、轨迹上倾角及轨迹波动起伏程度呈正相关性,而与管径和下倾角呈负相关性。预测范围内,气量、轨迹上倾和管径对水平井筒压力损失的影响最为明显,是水平井筒压降的关键影响因素。随着轨迹上倾角增加,水平井筒压降随气量的变化规律发生明显反转,低气量条件下水平井筒压降随气量的减小而增加,高气量下压降随气量增加而增加。

Gas-water flow law in horizontal wellbore and its influencing factors

Due to the change of flow direction and the continuous radial inflow of wall fluid, the flow law of gas and water in horizontal wellbore is quite different from that in conventional vertical well. Based on summarizing the results of previous studies, the horizontal wellbore gas-liquid two-phase prediction model is selected. After verifying the reliability of the model, considering in the wall inflow and the change of gas-liquid flow pattern, and changing multiple factors such as gas flow rate, water flow rate, pipe diameter, dip angle, trajectory fluctuation, and inflow positions for gas and water, etc., this study conducts a comprehensive predictive analysis on flow patterns, pressure distribution law and influencing factors of the horizontal section, and which can provides a theoretical basis for the production management and optimization of horizontal gas wells. The results show that there are three types of flow patterns in the horizontal wellbore under normal production conditions, i.e., stratified flow, intermittent flow and annular mist flow. The diameter and inclination of the wellbore have the most obvious influence on the gas-water flow pattern of horizontal wellbore, while the pipe wall inflow has little effect on flow pattern in the local wellbore. The pressure loss of horizontal wellbore is positively correlated with the gas flow rate, water flow rate, upward inclination angle of trajectory and trajectory fluctuation, and negatively correlated with the pipe diameter and downward inclination angle. Within the predictive range, gas flow rate, upward inclination of trajectory and pipe diameter shows the most significant influence on the pressure loss of horizontal wellbore, which are the key influencing factors of the pressure drop of horizontal wellbore. As the inclination angle of trajectory increases, the pressure drop of horizontal wellbore shows a significant reversal with the change of gas flow rate. Under the condition of low gas flow rate, the pressure drop of horizontal wellbore will increase with the decrease of gas flow rate; under the condition of high gas flow rate, it will increase with the increase of gas flow rate.