气体钻井最小气体体积流量计算新方法

A New Calculation Method of Minimum Gas Volume Flow Rate for Gas Drilling

目前气体钻井时主要采用Angel模型计算注气量,但与实际注气量相比,Angel模型的计算结果往往偏小。为此,结合最小速度理论,首先计算得到携带岩屑所需的最小流速,然后采用最小动能方法求解气体钻井所需的最小气体体积流量。考虑气体流量、环空截面积等因素对气体钻井所需最小气体体积流量的影响,引入颗粒群系数与阻力系数对计算结果进行了修正,使求解得的气体钻井最小注气量更加准确。计算结果表明,修正模型的计算结果比Angel模型更符合现场实际情况,机械钻速、井眼直径对气体钻井最小气体体积流量的计算结果也有很大影响。

Nowadays,gas injection rate for gas drilling is mainly calculated by means of Angel model,but its calculation results are frequently lower than the actual gas injection rates.Therefore,this paper firstly calculates the minimum flow rate necessary for cutting carrying based on the minimum velocity theory,and then calculates the minimum gas volume flow rate required for gas drilling by means of minimum kinetic energy method,the effects of gas flow rate and annulus cross-sectional area on the minimum gas volume flow rate in gas drilling have been analyzed,and particle group coefficient and resistance coefficient are introduced to correct the calculation results,so as to keep the minimum gas injection for gas drilling more accurate.The calculation results indicated that the corrected model is much more accordant with the practical situations than the Angel model,and the calculated minimum gas volume flow rate for gas drilling is greatly affected by the penetration rate and the borehole size.