Abstract
More than 30% of the wells worldwide are reported to have unplanned Sustained Casing Pressure (SCP) / Sustained Annulus Pressure (SAP) based on recent data1 . The issue greatly impacts production methods of field development with subsequently large impact on well expenditure. Several techniques are available to repair SCP/SAP however, they are mostly limited by rate of circulation and injectivity during squeezing and placing cementitious material behind casing. The objective of this paper is to demonstrate and share experience gained in the Gulf region to apply innovative placement methods of an alternative material (epoxy) for well repair of SAP in cases of no injectivity to cure fluid migration behind casing.
The most common and widely used practice to cure SAP/SCP behind casing is conventional casing milling and / or perforation with subsequent cement lock-up squeeze with subsequent pumping cementitious material from surface to the annulus. Unfortunately, this practice has a low success rate. Circulation cementing squeeze is not practical in many cases since we conduct primary cement job with cement to the surface and in many cases conduct subsequent "top up" job. There is an advanced solution using PWC-Perforate, Wash and Cement with special tool, that delivers reliable results, however it requires to have interval with poor cement isolation. The proposed advanced Downhole Annular Repair method has been utilized in the Gulf region country to cure sustained annulus pressure behind production casing. The method allows a single wireline run to accomplish successful SAP curing with following major steps: Positioning/anchoring tool at desired depth; gain access behind casing via a set of radial perforations and placement of epoxy resin using internal pump in the hesitation injection over the extended period of time.
The 4 wells have been treated using the innovative placement and alternative material to cure SAP behind production casing. Sealant has been injected using hesitation mode for a period of 10-20 hrs until initial setting time is reached. Well commissioning results demonstrated successful SAP treatment on 4 wells.
