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Gas Storage Conversion (5 Wells)Abstract：
In Sept, 2007, TOP WELL used snubbing technology to pull the strings out of the hole of 5 wells under pressure in the West to East gas storage project which marks the successful completion of the supporting capacity of West to East gas transmission
Details
Jintan Gas Storage Wells
Synopsis: Remove 114mm (4.5”) Production Strings
In Sept, 2007, TOP WELL used snubbing technology to pull the strings out of the hole of 5 wells under pressure in the West to East gas storage project which marks the successful completion of the supporting capacity of West to East gas transmission from Tarim of Xinjing to Jintan, Jiangsu.
Top Well was approached by the customer for help in removing existing strings of 114mm (4.5”) tubing from 5 of their wells. The wells had been producing and had declined to the point where the customer wished to utilize the wells for storage rather than production.
Well Data:
- Tubing: 114mm (4.5”) NUE
- Casing 177mm (7”)
- Surface Pressure: 11 Mpa (1600 Psi)
- Well Depths: 1100 Meters (3600’)
The first step in these wells was to plug the tubing strings. Wireline was rigged in and “PXN” plugs were set in each of the wells. The customer wished to follow a dual barrier concept throughout the work and because there was only one profile in the strings, the decision to set permanent bridge plugs above the “PXN” plugs was made. Each of the wells had a bridge plug that was supplied by Top Well set via electric wireline.
After the plugs were set, the tubing was aligned to a choke manifold and bleed off to flare. The upper section of the well head was removed above the tubing hanger. The following stack was rigged up and pressure tested to 35 Mpa (5K)
- 10M {70 MPA} Flow Cross c/w 10M {70MPA} double Gate Valves both sides
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10 M{70 MPA} double gate BOP
- Bottom Cavity dressed with Blind rams
- Top Cavity dressed with Shear rams
- 10 M {70 MPA} single gate BOP dressed with 2.875” {73mm} safety fronts
- 10 M {70 MPA} single gate BOP dressed with 2.875” {73mm} safety fronts
- 10 M {70MPA} x 5M {35MPA} crossover
- 5M {35MPA} rig assist snubbing unit
Primary Bop and Snubbing Unit Rigged Up
As additional well control, the wellhead already incorporated two 179mm (7.062”) x 70 Mpa (10K) master valves below the tubing spool. These valves would be used to close in the well after the tubing was snubbed out of the hole.
Tripping Operations
The pipe was tripped out of the hole using the workover rig while pipe heavy and using the snubbing unit jack when pipe light. Once the last joint was above the master valves, the wells were shut in and secured. All Top well equipment was rigged out.
