Drilling String & Components PDF

DRILLING STRING & COMPONENTS 1 Prepared by Eng. Mohammed E,Mehrez 2021 2 AGENDA What is Drill String? Duties of Drill String Components Kelly DP HWDP Drill Collar Jar Crossovers Stabilizer...

DRILLING STRING & COMPONENTS 1 Prepared by Eng. Mohammed E,Mehrez 2021 2 AGENDA What is Drill String? Duties of Drill String Components Kelly DP HWDP Drill Collar Jar Crossovers Stabilizer Reamerler Shock-Eze What is Drill String? The drill string is an important part of the rotary drilling process. It is the connection between the rig and the drill bit. Although the drill string is often a source of problems such as washouts, twist-offs, and collapse failures, it is seldom designed to prevent these problems from occurring. In many cases, a few minutes of drill string design work could prevent most of the problems Drill String? The tubular connection from surface system down to the bit  Duties of Drill String? -provide a fluid conduit from the rig to the bit -impart rotary motion to the drill bit -allow weight to be set on the bit -lower and raise the bit in the well In addition, the drill string may serve some of the following specialized services: a-provide some stability to the bottom-hole assembly to minimize vibration and bit jumping, allow formation fluid and pressure testing through the.b drill string, permit through-pipe formation evaluation when logging.c tools cannot be run in the open hole, 5 Kelly Transmits the rotary motion generated from the rotary table to the drill string via the kelly bushing It has been replaced by TD systems 6  DrillPipe The longest section of the drill string is the drill pipe. The BHA is usually no longer than 1,000 ft. Each joint of drill pipe includes the tube body and the tool joint, which connects the sections of drill pipe. Although aluminum drill pipe is sometimes used in special projects, it will no t be presented in this section. However, it does have important applications in remote areas where airfreight is required and where otherwise the rig would have insufficient hoisting capacity. Drill pipe is available in several sizes and weights 7 DP Classification According to API, DP’s are classified as follows; Length.I Minumum Yield Strength.II Wear.III 8  DP Classification Length; Range – 1 18 ft – 22 ft Range - 2 27 ft – 30 ft Range - 3 38 ft – 45 ft 9 DP Classification Minumum Yield Strength; Minimum yield strength is the point where the tubular goes to Plastic Deformation zone from Elastic deformation zone 10  DP Make-up Torque Make up torque is the recommended amount of torque to apply when tightening your drill pipe prior to running it down the hole. The amount depends on the connection, the inside diameter of the pin, and the outside diameter of the box. A lot of common thread problems can be traced back to improper make up torque. If too little is applied (running loose), then connections could continue to tighten during drilling and over tighten (over torque) causing box shoulders to mushroom and pins to stretch and/or break (Think of an impact wrench). Too much torque applied at the table can lead directly to mushrooming & pin breakage. 19 Drill Pipe M/U B/D 20  Heavy Weight Drill Pipe The use of heavy weight drill pipe -Reduces drilling cost by virtually in the drilling industry has eliminating drill pipe failures in the become a widely accepted transition zone. practice. The pipe is available -Significantly increases performance in conventional drill pipe outer and depth capabilities of small rigs in diameters. shallow drilling areas through the case However, its increased wall of handling and the replacement of thickness gives a body weight some of the drill collars. 2-3 times greater than regular -Provides substantial savings in drill pipe. Heavy weight drill directional drilling costs by replacing pipe provides three major the largest part of the drill-collar string, benefits to the user reducing down hole drilling torque, and decreasing tendencies to change direction. 23 HWDP 24