By Trudy Curtis, CEO, Professional Petroleum Data Management Association (PPDM)

API NUMBER 2013

By Trudy Curtis, CEO, Professional Petroleum Data Management Association (PPDM)

September 3, 2013

A revised Well ID system will help the US O&G industry.

For almost half a century, the American Petroleum Institute’s API Well Number (based on API Bulletin D12A) has been a workhorse of the US O&G industry. Operators use it to label, store and retrieve well information, and to report information to the regulatory agency. Regulatory bodies use it to track drilling permits, collect royalties from production, and optimize field conservation.

The original API Well Number was based on a 10 digit system (see Table 1). The first two digits identify the state, the next three digits identify the county, and the last five digits are unique numbers for each well in the county. The majority of regulatory agencies use a modified API Number series. In 1978, the API Well Number was expanded to 12 digits so that directional sidetracks could be identified. The rules for identifying sidetracks allowed considerable diversity in implementation, resulting in some fragmentation of usage between state agencies.

Table 1. API Well Number - 1978
(based on the API Bulletin D12A)
Positions: / 1-2 / 3-5 / 6-10 / 11-12
Code Name: / State / County / Unique Well Code / Directional Sidetrack
Example: / 31 / 101 / 229639 / 03

Over the last ten years, drilling and completion technologies have advanced tremendously, with multiple wellbores, laterals and production reservoirs associated with a single well surface location. The potential for downhole collisions has increased dramatically. A 12-digit number is required to uniquely identify each wellbore. Unfortunately, about half of the US state regulatory agencies continue to use a 10 digit API Well Number, and thus cannot identify all the drilled wellbores. Operators and vendors routinely add their own extensions to 12 or 14 digits, creating identifiers that unofficially emulate the API Well Number. This creates confusion when merging data from different sources, resulting in errors that can cost money or create hazardous situations.

Early in 2010, the API transferred stewardship of the API Well Number to the Professional Petroleum Data Management Association (PPDM). PPDM is a global, not-for-profit professional society that provides data management standards and best practices for the petroleum exploration and production industry. Petroleum companies, government agencies, software application providers, data vendors, service companies, standards bodies and individuals form the membership.

PPDM formed the Well Identification Project. Industry participants included Anadarko, BP, Chevron, ConocoPhillips, ExxonMobil, IHS, Chesapeake Energy, Baker Hughes, Devon, TGS, Llano Systems & Data Management and DrillingInfo, along with regulators. The goal was to create a new version that would honor existing standards but allow industry to identify and catalogue new well technologies in a consistent, universal manner. The Well Identification Project polled industry experts to find out what capabilities the new well ID system needed (and didn’t need).

PPDM then turned to upgrading the US well identification system. The API Number 2013 was formally launched in September, 2013. You can download the standard for free by visiting

The new identifier is called the API Number 2013, although no meaning is attached to “API”. Both the name and the design provide strong continuity with the past while supporting the data management demands of the future. The greatest change is that all wellbores (drilled footage) must be identified.

The API Number 2013 now incorporates 12 digits (see Table 2). The first ten digits are exactly the same as the old system. Digits 11 and 12, however, are reserved for new-cut hole, and identify each wellbore, including deepenings, in a consistent, standardized manner.

Table 2. API Number – 2013
(based on industry revision in 2013)
Positions: / 1-2 / 3-5 / 6-10 / 11-12 / 13+
Code Name: / State / County / Well / Wellbore / Extension (Optional)
Example: / 31 / 101 / 22963 / 03 / 00
Note: Only digits are allowed in positions 1 – 12.

The API Number 2013 has an optional extension to include more information. Positions 13+ allow for conversions, plugbacks and drilling modifications within the stated wellbore. It is not meant to identify a wellbore or deepening; those functions are reserved for digits 11-12.

The revised standard allows for improved financial, environmental, technical and safety performance, while still meeting contractual, social, and regulatory obligations. Senior management benefits from reduced risk in decision making. Geoscientists can spend less time searching for and reconciling data. Engineers can make better drilling and workover decisions. Regulators benefit from standardized reporting methodologythat ensures all wellbores are identified, and better satisfies environmental issues. Mergers & acquisitions activity encounters fewer errors. Data managers can improve the quality of databases and data exchange.The ultimate benefit is timely decision-making based on ready access to all the info about every wellbore.

PPDM is now working with state and federal regulators to help them implement the system. Any operator can independently adopt the system right now, but most companies are waiting for their regulators to embrace the system first, to avoid unnecessary revisions.

The PPDM Association welcomes comments on the API Number 2013. Please write to

The PPDM also seeks expert volunteers for other initiatives. To learn more about how you can participate, please visit

Media Contact: Cara Henry: T 403 668-9470,