Discussion on stability and applicability of gas lift reverse circulation drilling

Abstract:

The gas lift reverse circulation process has the advantages of high drilling efficiency, strong cutting carrying capability, good loss prevention effect and long bit life, etc., and can also increase the productivity of liquid minerals. However, it is generally believed that the suction action of gas lift reverse circulation drilling will produce negative pressure, which is not conducive to the stability of the well wall and not suitable for application in loose formations . In this paper, by calculating the hydraulic parameters of the gas lift reverse circulation drilling annulus, and discussing the well wall stability and applicability of gas lift reverse circulation drilling from the aspects of annulus pressure, drilling fluid flow state and flow velocity, it is pointed out that suitable combination of the drilling string and conditioning of drilling fluid properties can make the gas lift reverse circulation process more adaptable to different formations.