Abstract

The migration of gas to surface by means of the production casing/openhole and the production/surface casing annulus is a common occurrence in the petroleum industry. There are also situations wherein migrating gases will negotiate a route to surface outside the surface casing.

The repair of these situations is a non-revenue generating exercise with the potential to reach significant expenditures. The recommended strategy will efficiently initiate and direct this process consequently minimizing the total cost of this intervention. The process commences with a logical technical approach to identify the gas source or sources that are responsible for the problem. The next step is to communicate with this gas source in a manner that enhances a remedial cementing activity. It concludes with the task of cement squeezing the source using a low rate cement squeeze technique to permanently seal the gas source thus preventing gas flow. This methodology has proven to be extremely successful and the subject paper describes in detail the recommended methods for identification, access to and sealing of the gas source responsible for these issues. Case histories will also be presented to illustrate strategies within the intervention.

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