Drill pipe protector

#This invention relates generally to non-rotating drill pipe protectors attached to a drill string, and more particularly, to improved low-friction drill pipe protectors by incorporating a soft elastomer liner and low-friction end pads.

#The drilling of holes or bores into underground formations and particularly, the drilling of oil and gas wells, is typically accomplished using a drill bit which is attached to the lower end of an elongated drill string. The drill string is constructed from a number of sections of tubular drill pipe which are coupled at their ends to form the “drill string”. The drill string extends from the drilling surface into a well or “wellbore” which is formed by the rotating drill bit. As the drill bit penetrates deeper or further into an underground formation, additional sections of drill pipe are added to the drill string.

#Casing is generally installed in the wellbore from the drilling surface to various depths. The casing lines the wellbore to prevent the wall of the wellbore from caving in and to prevent seepage of fluids from the surrounding formations from entering the wellbore. The casing also provides a means for recovering the petroleum if the well is found to be productive.

#FIG. 1 is a schematic side elevational view, partly in cross-section, showing a string of drill pipe having drill pipe/casing protector assemblies according to this invention installed between tool joints of the drill pipe in a deviated well being drilled in an underground formation;

#FIG. 2 is a detail view of FIG. 1 illustrating one drill pipe joint and one drill pipe protector;

#FIG. 3A is a front cross-sectional view of a first embodiment of a hydrolift drill pipe protector assembly constructed according to the principles of the present invention;

#FIG. 1 illustrates a well drilling system for drilling a well in an underground formation 10. A rotary drill string comprises a plurality of elongated tubular drill pipe sections 12 which drill a well bore 14 with a drilling tool 15 installed at the bottom of the drill string. An elongated cylindrical tubular casing 16 can be cemented in the well bore to isolate and/or support formations around the bore. The invention is depicted in a deviated well which is drilled initially along a somewhat straight path and then curves near the bottom and to the side in a dog leg fashion. It is the drilling of wells of this type that can substantially increase the torque applied to the drill string during use, and where the present invention, by reducing the amount of torque build up, makes it possible to drill such deviated wells to greater depths and to drill them more efficiently while preventing damage to the casing and drill pipe.

#The invention is further described herein with respect to its use inside a casing in a well bore, but the invention also can be used to protect the drill pipe from damage caused by contact with the wall of a bore that does not have a casing. Therefore, in the description and claims to follow, where references are made to contact with the wall or inside diameter (I.D.) of a casing, the description also applies to contact with the wall of the well bore, and where references are made to contact with a bore, the bore can be the wall of a well bore or the I.D. of a casing.

#As illustrated, separate longitudinally spaced apart drill pipe protector assemblies 18 are mounted along the length of a drill string to protect the casing from damage that can occur when rotating the drill pipe inside the casing. The sections of the drill pipe are connected together in the drill string by separate drill pipe tool joints 20 which are conventional in the art. The drill pipe can produce both torque and drill pipe casing wear and resistance to sliding of the drill string in the hole. The separate drill pipe protectors 18 are mounted to the drill string 12 adjacent to each of the tool joints to reduce drill string torque, reduce sliding friction forces, reduce shock and vibration to the drill string and abrasion to the inside wall of the casing.