Drilling string include

• Drill Collar, short Drill Collar, Non-magnetic Drill Collar

• Drill pipe, Pup joint

• Heavy-Weight Drill pipe

• Stablizer

• X-over Subs

• Roller Reamer

• Casing Scraper

• Down hole mud motor

• Drilling jar

• Drill bit

 

The  API  specifications for a drilling string are API Spec 5DP for drill pipe and API Spec 7-1 for other rotary drill stem elements like heavy-weight drill pipe and drill collars. These standards ensure compatibility, quality, and performance across the oil and gas industry. 

Key API specifications related to the drill string include:

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Design and Manufacturing

• API Spec 5DP: This core standard specifies the technical delivery conditions for steel drill pipe, including different product specification levels (PSL-1, PSL-2, PSL-3) with increasing requirements for quality and testing. It also defines various grades based on minimum yield strength:

  • E-75: Standard grade, 75,000 psi yield strength, for moderate depth wells.

  • X-95: Intermediate strength, 95,000 psi.

  • G-105: High strength, 105,000 psi.

  • S-135: Highest strength, 135,000 psi, for deep or challenging wells.

• API Spec 7-1: This specification covers other crucial drill stem components such as drill collars, heavy-weight drill pipe (HWDP), and stabilizers. It outlines requirements for mechanical properties, dimensions, and material quality. 

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Connections and Threading

• API Spec 7-2/ISO 10424-2: This standard details the specifications for threading and gauging of rotary shouldered connections, which are essential for joining drill string components. Common API thread types include Regular (REG), Internal Flush (IF), Full Hole (FH), and the standardized Numbered Connections (NC) series. 

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Inspection and Maintenance

• API RP 7G-2: Known as the "Recommended Practice for Inspection and Classification of Used Drill Stem Elements," this is a crucial guide for evaluating the condition of used components (pipe body, tool joints, collars, etc.) to ensure their continued integrity and safety.

• API RP 7G: Provides guidelines on the proper use and maintenance of the drill string to extend its service life and improve performance. ​

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