AT A GLANCE
Where: Offshore Peninsular Malaysia
Scope: 10-well P&A offshore campaign
Shallow surface casing leak remediation to address annular integrity issues including sustained annular pressure (SAP) inside the B-annulus.
Two wells with similar casing designs had B-annulus SAP between the 7” and 10-3/4” surface casing. The source was believed to be a shallow hydrocarbon gas sand at approx. 500m with cement channeling from the 10-3/4” surface casing shoe.
Well 1 had 500 psi B-annulus pressure prior to the operations. Well 2 had 130 psi B-annulus pressure prior to operations. The pressures were stabilised and the annulus was then kept closed throughout PWC® operations.
After waiting on cement, the annuli were bled down to zero, and the plugs verified by 10,000 lbs tag and 1,000 psi pressure test.
Subsequently, after several days, both wells exhibited annular pressure build up at surface – to 95 and 75 psi respectively. However, after a series of bleed-offs both wells stabilized at 0 psi and the well barriers were confirmed good by the customer.
HydraWell has been delivering PWC® scopes in Malaysia since 2016, with 33 successful operations to date. This 10 well P&A campaign saw severe corrosion in the surface casing below the wellhead. Some wells required epoxy resin reinforcement prior to rigless intervention with a hydraulic workover rig.
12 PWC® barrier plugs were installed to address annular integrity issues, including sustained annular pressure (SAP) inside the B-annulus. This was a complex scope due to risks with surface handling and of penetrating outer surface casing during sustained annular pressure remediation.
To manage surface handling risk due to shallow perforating tubing shock, a customised PWC® system compatible with mechanical perforating system was used. HydraWell’s integrated design approach addressed unplanned well conditions and system tests prior to operations determined optimum operating parameters.
A mechanical perforator with a custom designed jet based PWC® tool was selected for installing the shallow annular plugs to avoid the risk of penetrating the outer casing.
Tandem mechanical penetrators were configured to reduce the perforating time by 50%. 2 x 4 slots were created with each tool activation and the tool was rotated after each activation to create 45 slot phasing with large access window to the annulus.
The jetting wash and cement sequence was conducted in a separate trip. Two standard downward/upward wash passes with custom designed wash tool across large slot perforations were conducted at 6 bpm, 0.3 m/min and 60 RPM in a rigless environment with limited rig capability.
Intermittent high vis gel pills were pumped to aid in hole cleaning. A high volume of cement cuttings and debris was observed throughout washing in both wells. Cement plugs were set at the shallow depth of ± 420mMD and tagged at desired TOC to comply with PPGUA guideline.
RESULTS & BENEFITS
An optimised jet design compatible with mechanical perforation geometry and close collaboration with fluids and cement design team ensured washing and cement procedures were followed minimising plug contamination.
As a result the customer PWC® operations were successfully performed without damage to the outer casing avoiding compromising integrity and managing unexpected well conditions.
The customer saved significant time, estimated at approx. 5 days per well, compared with section milling and was able to eliminate SAP from multiple sources and achieved all abandonment objectives.
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