What's the best way to choose drill bits and string components for different formations and well objectives?

1 Formation characteristics

The first step in choosing your drill bits and string components is to understand the formation characteristics that you will encounter in your well. These include the hardness, abrasiveness, heterogeneity, and compressive strength of the rock, as well as the presence of fluids, fractures, and faults. These factors affect the wear and tear, penetration rate, and stability of your drill bits and string components, as well as the potential risks of stuck pipe, hole deviation, and formation damage. You should use reliable data sources, such as well logs, core samples, and offset wells, to analyze the formation characteristics and select the most suitable equipment for each section of your well.

2 Well design

The second step in choosing your drill bits and string components is to consider your well design and objectives. These include the well depth, diameter, trajectory, inclination, and target zone, as well as the expected production rates, reservoir properties, and completion requirements. These factors affect the load, torque, and bending stresses on your drill bits and string components, as well as the hydraulic and mechanical efficiency, hole cleaning, and borehole quality of your drilling operations. You should use appropriate software tools, such as well planning, hydraulics, and bit selection programs, to design your well and select the most compatible equipment for each stage of your drilling process.

3 Drilling parameters

The third step in choosing your drill bits and string components is to optimize your drilling parameters, such as weight on bit, rotary speed, flow rate, and mud properties. These parameters affect the performance, durability, and reliability of your drill bits and string components, as well as the rate of penetration, vibration, and hole cleaning of your drilling operations. You should use real-time data, such as downhole measurements, surface sensors, and drilling reports, to monitor and adjust your drilling parameters and select the most efficient equipment for each drilling condition.

4 Operational constraints

The fourth step in choosing your drill bits and string components is to account for your operational constraints, such as budget, time, availability, and regulations. These constraints affect the feasibility, cost-effectiveness, and safety of your drill bits and string components, as well as the risk of non-productive time, equipment failure, and environmental impact of your drilling operations. You should use reliable sources, such as equipment catalogs, supplier recommendations, and industry standards, to compare and evaluate your equipment options and select the most suitable equipment for each operational scenario.

5 Drill bit types

The fifth step in choosing your drill bits and string components is to familiarize yourself with some of the common types of drill bits that are available in the market. These include roller cone bits, fixed cutter bits, hybrid bits, and specialty bits, each with different features, applications, and limitations. Roller cone bits have three rotating cones with teeth or inserts that crush and shear the rock. Fixed cutter bits have a single piece of matrix or steel with cutting elements, such as polycrystalline diamond compact (PDC) or natural diamond, that scrape and grind the rock. Hybrid bits combine features of both roller cone and fixed cutter bits, such as having a single cone with PDC cutters. Specialty bits are designed for specific purposes, such as coring, reaming, or underreaming. You should understand the advantages and disadvantages of each drill bit type and how to match them with your formation characteristics, well design, drilling parameters, and operational constraints.

6 String components

The sixth step in choosing your drill bits and string components is to familiarize yourself with some of the common types of string components that are used in conjunction with your drill bits. These include drill collars, stabilizers, reamers, subs, jars, accelerators, and shock tools, each with different functions, configurations, and specifications. Drill collars are heavy and rigid tubulars that provide weight and stiffness to your drill bit. Stabilizers are devices that prevent excessive hole deviation and vibration by centralizing your drill string. Reamers are tools that enlarge or smooth the hole by cutting or scraping the wall. Subs are short sections of pipe that connect different components of your drill string. Jars are tools that deliver an upward or downward impact to free a stuck drill string. Accelerators are tools that amplify the impact of jars by storing and releasing energy. Shock tools are tools that absorb and dampen the shock and vibration from your drill bit. You should understand the functions and limitations of each string component and how to optimize them for your well design, drilling parameters, and operational constraints.

7 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?