Research On Technology Of Multi-Stage Variable Diameter With Reamer Tool While Drilling

Drilling and reaming refers to the use of reaming tools to expand the size of the borehole while the drill bit is being drilled.It was developed in the 1990 s to solve a series of problems such as borehole necking and wall collapse,and is now being developed as an important tool to deal with drilling anomalies.It is an advanced technology that can solve the problem of necking in plastic formations,optimize casing procedures,improve cementing quality and reduce drilling costs by saving start-up and downhole time.The main forms of reamers include double-centered bits,fixed-wing eccentric reamers and telescopic reamers.The telescopic reamers are divided into mechanical and hydraulic types according to the driving method of the cutter wings.The multi-stage variable diameter drilling and reaming technology is an improvement on the existing drilling and reaming technology,which can achieve a variety of borehole size expansion in one startup and down-drilling.In this paper,based on the summary of domestic and foreign literature and the patents related to borehole reamers,a new hydraulic borehole reamer is designed to realize the expansion of multiple borehole sizes in one drilling start.The main research contents of this paper include:(1)A new type of multi-stage variable diameter hydraulic follow-hole reamer is designed,and the start-up principle of the reamer and the uncoupling principle of the reamer are theoretically analyzed to optimize the reamer-related dimensions.(2)The hydraulic structure of the reamer has an important influence on the rock breaking efficiency of the eye expander.In this paper,the pressure and velocity variation patterns of drilling fluid flowing from a single nozzle in the jet and diffuse flow zones are presented to analyze the purification effect of drilling fluid on rock chips.With the help of Fluent analysis software,we study the change of flow field near the flank of the eye expander after the drilling fluid flows out from the nozzle in order to optimize the hydraulic structure of the eye expander to achieve the purpose of rock cleaning and mud pack prevention.(3)The design of the cutting structure of the eye expander is studied,and the rockbreaking work is done by using the way of assembling PDC teeth on the eye expander wing,and the contour of the reaming wing and the arrangement of PDC teeth on the eye expander wing are studied by using theoretical analysis and ABAQUS finite element simulation to optimize the rock-breaking efficiency of the eye expander.