WELL NO: BJN-8. Lower master valve

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3 WELL NO: BGN-8.; LOC: BGH Well BGN-8 came into production on 9 th Feb Initially the FTHP = 4000 psi, CP=2400 psi and 5 1 / / 8 annulus pressure = 600 psi. The well was produced at Baghjan of 24 KLPD. WELL NO: BJN-8 During production, leakage was noticed through the Lower Master Valve and one of the Casing Valve. It was decided to go for W/O operation to replace the leaky well head valves. Lower master valve On 15/05/09, Tbg. was punctured just above the packer at the range from 3766m m with 4 holes of 0.45 dia. to establish communication from Tbg. to 5.1/2 casing. # Attempt was made to kill the well with 80 pcf Sodium formate solution using conventional method. Casing valve The well could not be killed even after 4 times of hole volume (a total of 857 bls against 216 bls of hole volume.) following conventional method.

4 CMT was asked to take-over the charge of Killing operation of the well on 25 th June,09. WELL NO: BJN-8 Kill Pump Kill Manifold Choke Manifold GM(P) organized a meeting at production conference hall in the 2 nd half on 25 th June, where in well problem was discussed in detail with reference to the presentation given by Production Commissioning section. Crisis Management department assured that the well can be killed using proper equipment & well control method with 77 pcf kill fluid. Accordingly, a team was formed including executives from CMT, P(O), Drilling, Chemical department under the leadership of Sri K. Saikia, CE(D)-CMT. The team visited the well BGN-8 on 26 th June, inspected all pressure handling equipments and decided to replace the existing Choke Manifold by new Choke Manifold with remote control panel.

5 A new Choke Manifold with Remote Control Panel was transferred to the well after thorough check up at drilling equipment yard on 27 th June. (transferring of kill fluid from other location to the well was in progress) New Choke Manifold Operating lines and other equipments could not transferred to well on 28 th June due to Road Blockade by local people. Remote Control Panel On 29 th June, the Choke Manifold with Remote Control Panel was commissioned and tested.# All the lines, Kill Manifold, Choke Manifold etc. was tested up to 4600 psi. and the system was made ready to kill the well. 77lb/cft kill fluid was also made ready. On 30 th June, SITP=3400 psi and SICP=3400 psi Bleed off well surface gas from both Tubing and Casing. Recorded SITP=3000 psi and SICP=2800 psi 1. Reservoir Pressure = 46 kg above hydrostatic = 6136 psi 2. Pressure Exerted by hole fluid = = 3136 psi 3. Equivalent Mud weight in hole at shut in condition = 36 lb/cft. 4. Required Kill Mud Weight = 77 lb/cft (considering 450 psi overbalance) Re-checked all the calculated values prior to killing the well. Pressure tested all the lines prior to killing. Made step-down kill sheet.

6 Brief Operational Sequence: Conducted a Tool Box meeting with all the persons present at the site. Explained safety matters during killing & Assigned duties of each & every person including security, Fire Service. Started pump at 3:15 pm and gradually increased the SPM to Kill Rate (80 SPM) keeping SICP constant. Return flow was diverted to EPS to separate gas at Test separator. Pumped Kill Mud (77 lb/cft) from Surface to Tbg. Punchered Point (3754m ) following Step- down Kill Sheet. Pump Kill Mud from Tbg. Punchered point to casing till kill mud reaches at surface maintaining Final Circulating Pressure. Diverted the return flow to well site Production tank after pumping the hole volume. At 5:45 pm checked and found both the Tbg. & Csg. Pressure Zero. Diverted the return flow to well site Mud tank after receiving 77 lb/cft fluid on return. Circulated for another ½ hr. and handed over the well for W/O operation as per plan.

7 Tubing and Casing pressure during well killing (in ideal condition) Pressure Casing Pressure Tubing Pressure Strokes

8 Pressure Pressure behaviour during killing using conventional method TUBING Number of Strokes ANNULAS (5½ CASING)

9 Phenomenon during killing using conventional method Applied Un-calculated imaginary Back Pressure

10 Pressure Pressure behaviour during killing using conventional method TUBING Number of Strokes ANNULAS (5½ CASING)

11 Phenomenon during killing using W&W Well control method Applied Calculated & Designed Back Pressure

12 m 2000 m 3000 m 3754 m KM Pumping Depth 0.00 m 1000m 2000m 3000m 3754m Surface Pr KM Coln. Pr OM Coln. Pr Exerted Total Pr. at 3754m Formation Pr O/balance

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15 WELL NO. BGN 8 (LOC. BGH) (as on ) (Not to scale) D.F. Elev: m asl G.L. Elev: m asl Dev Corr : m GLV at 598 m Surface pressures recorded on showed in tubing - casing annulus and casing annulus (5.1/2 X 9.5/8) as 295 Ksc & 240 Ksc respectively. Cement top behind 9.5/8 Casing :1458 m (as per CBL-VDL recorded on ) 9.5/8 Casing shoe at m SLB punctured the tubing at 3776m m (4 shots) 2.7/8 OD EUE N-80 tubing with one GLV and hydraulic packer set at 3800 m (As per logging,tbg shoe at 3792 m) Perforations: m 5.1/2 Float Collar/ Casing Shoe = / m 22 m D.C.

16 Step-down Kill Sheet Number of Stroke Pumping Pr. (psi) (A) Vol. (bls) Pumped Pr. Drop (psi) (B)

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19 Defective wellheads of Greater Hapjan Area Sl No Well Defects Remarks 1 Baghjan-6 Leakage observed from gate of top valve. The valve was replaced. Recently leakage observed from the gland of the side valve, while opening the S/I well. The leakage vanishes once the well starts to flow. 2 Baghjan-4 Leakage observed from the gate of the top valve while opening the S/I well. The leakage vanishes once the well starts to flow. X mass tree make: Parveen Ratings: psi, FTHP = 3400 psi X mass tree make: Parveen Ratings: psi FTHP= 3800 psi 3 Baghjan-2 Similar problem as Baghjan-4 X mass tree make: Parveen Ratings: psi FTHP= 2100 psi 4 Barekuri-6 Leakage observed from gate of top valve. The valve was replaced. 5 Baghjan-8 On leakage observed from the grease injection point of the lower master valve. It was observed that the grease injection nipple came out of its original position and a gas was sprayed from that point.. In addition to this, leakage was also observed from the top valve. 6 Makum-18 Bonnet cover of the master valve was stolen by miscreants. At present the master valve cannot be operated. X mass tree make: Parveen Ratings: psi FTHP= X mass tree make: Parveen Ratings: psi FTHP = 4000 psi, CP=2400 psi X mass tree make: Parveen Ratings: 5000 psi FTHP= 800 psi 7 Makum-29 Similar problem as Baghjan-4 and Baghjan-6 X mass tree make: Parveen Ratings: psi FTHP= 3800 psi 8 Hapjan-48 Leakage observed from the gland of the arm valve. Valve replced. X mass tree make: Parveen Ratings: psi FTHP= 3380 psi