Millions of oil and gas wells, water supply wells, and wells installed for environmental monitoring and remediation purposes, have been abandoned. The need to determine the locations of these abandoned wells is based on safety and threats to the environment. Improperly constructed or abandoned wells may pose a safety threat to humans and animals, may be sources of brines and other undesirable fluids coming to the surface, may be conduits for transport of contamination from the surface to the substrate, or may cross-contaminate water-bearing zones in the subsurface. All states do not require documentation of the abandonment of wells and may not have specific requirements for abandonment procedures.

1.1 This guide provides an approach to selecting and implementing a program to identify the locations of abandoned wells. This guide provides descriptions of methods to be used as starting points in the search for these locations. It is not intended to be a step-by-step procedure to conduct the search program. This guide also provides listings of government agencies that may have well location information. It is understood that addresses and phone numbers change and that the included information may not be accurate in the future.

1.2 The described methods are approaches that have been used at many sites across the United States. Other methods may be appropriate. Typically, several approaches are used to obtain acceptable confirmation of well locations. This guide is not limited to specific wells. The method chosen should be appropriate for the size of the area being searched and the type of well being located. Some well types and construction materials may preclude their detection by any of the methods described.

1.3 This guide offers an organized collection of information or series of options and does not recommend a specific course of action. This guide cannot replace education and experience and should be used in conjunction with professional judgement.