Practice of Sustained Casing Pressure Removal for JZ Gasfield Production Well Plug and Abandonment in Bohai Bay

Abstract

There are three wells with poor well integrity and high sustained annulus pressure(SAP) in JZ Gasfield. In order to remove the sustained pressure, remediate the poor well integrity and abandon wells in compliance with national regulations, plans, methods and practice taken were discussed in this paper. The occurrence reasons and source of pressure were identified first. And the different remediation and treating programs were made according to evaluation of the popular and good practice around the world. The best killing and cementing method were taken. Casing strings recovered by section mill and bullhead cementing process were chosen as one of the effective plans to solve problems like this. These three wells with sustained casing pressure were abandoned successfully and effectively. The most complicated well was dicussed in detail. Well abandonment plans for gasfield were made in detail. Abrasive waterjet cutting system were utilized first time. Lessons gained in the well plug and abandonment execution phase can be applied in other regions, especially in Asia Pacific. A series of practice taken to handle SAP were described in this paper for the first gasfield abandonment and decommission project in China. These experiences shared both in China and other regions around the world, this could offer some help for others to handle situations like this.