Analysis of Cuttings Transportation during Drilling Gas Horizontal Wells

The technique of gas drilling has been widely applied in home and abroad.It is mainly used to increase rate of penetration(ROP),detect hydrocarbon reservoir and solve circulation loss.The volume of gas injection is the critical parameter in gas drilling.The calculation of volume of gas injection in gas horizontal drilling is still a difficulty problem.The difference between the calculated and the actual value used in field is large which brings a lot of difficulties in real gas drilling.In this paper,a mechanical analysis of the cuttings in the horizontal section of well where it is difficult to lift the cutting in gas drilling well was analyzed.Based on bulk mechanics and gas dynamics,the required gas velocity for cuttings to move under different wellbore angle,cutting size and friction coefficient was analyzed.It shows that it is difficult to life cuttings in horizontal section where drilling string is near the lower wall of hole,but also in section of high deviation angle.It provides theoretical references to flow calculation in gas horizontal drilling.