scope:

General Considerations

This document provides guidance for the design, placement, and verification of cement plugs in wells to be temporarily or permanently abandoned, as well as remediation and verification of annular barriers. Wells temporarily abandoned (suspended) are intended to be re-entered in the future. The placement of barriers may depend on whether the well is to be temporarily or permanently abandoned.

The information in this document is general in nature. Wellbore plugging and abandonment practices will vary with regulatory requirements, well type, and purpose. Sound engineering and operational practices should be applied to each wellbore plugging operation. Cement plug lengths are not considered in this document.

Well Construction and Abandonment Practices

This document assumes that generally accepted well construction practices were followed during the installation of the cemented casings.

As specified in API 65-2, properly designed casing strings cemented in place provide multiple barriers during well operations.

Abandonment barriers may include those placed:

- across any exposed casing/liner shoe;

- in open hole;

- above perforated intervals in cased hole;

- at points where casing has been removed;

- across liner tops;

- above and below usable water sources;

- above or below hydrocarbon bearing zones or other potential flow zones;

- at the surface or mudline.

See Figure 1 for an example of a permanent well abandonment.

NOTE 1 Plug #1 may cover all open hole length in several cases.

NOTE 2 Plug #3 is commonly called a casing stub plug or "T" plug.

NOTE 3 Plug #6 is commonly called a surface or environmental plug.

NOTE 4 Top of cement in casing strings can vary depending on well construction.