Tooth arrangement design of retractable DTH hammer bit used for drilling while casing

Down-the-hole(DTH)hammer with casing while drilling(CWD)is a technology that has been proven to be able to alleviate many of the problems faced by complex formations.However,the drill bit is suffered from rapid wear,low drilling efficiency,and high energy consumption due to the unreasonable tooth arrangement and impact energy selection in drilling process,which affect the application effect of this technology.ABAQUS software was used for numerical simulation of rock breaking behavior under impact load with the single,three,and five teeth arrangement drill bit respectively,to improve the application effect and solve the aforementioned technical problems.Based on the calculated parameters of tooth arrangement,we designed a novel drill bit for hard rocks and provided a theoretical basis for the tooth arrangement of largediameter drill bits.

A review on casing while drilling technology for oil and gas production with well control model and economical analysis

The extraction of petroleum fluids from sub-surface accumulations mandates the drilling of a well into the formation containing the accumulation.The drilling techniques have evolved over time to overcome several challenges while some of the issues still prevail with the currently used drilling practices like loss circulation,large tripping time to change bottom hole assembly,stuck pipe problems and low well bore stability,to name a few.These decrease the drilling efficiency and increase the Non-Productive Time(NPT)of this highly capitalintensive industry encouraging the Petroleum Industry to look for new technology.Casing while Drilling(CwD)is a technique of drilling which has been proven to alleviate many of the problems faced while drilling.In this method,drilling and casing of a well bore is carried out simultaneously,which improves the drilling efficiency by reducing the NPT.It has proven to be beneficial in controlling loss circulation and improving wellbore stability by‘Plastering’effect,high quality cement job and increased rig floor safety.It uses smaller rig and less fuel thereby reducing carbon footprint in the environment.This paper studies comprehensive well control and casing string design consideration.Economics encourages its application that has been discussed in the paper.A case study on the application of CwD in Malay basin for top hole drilling is presented.Finally,the paper briefly outlines the technical challenges that need attention to get better results from CwD.