BOP - Pressure Testing

PRESSURE TESTING OF BOPs & CHOKE MANIFOLD TEST FLUID Clean water should be used as test fluid. TEST FREQUENCY BOP stack should be pressure tested (1) when installed. (2) after setting each casing string. (3) prior to entry into a transition zone. (4) not less than once a week. (5) following repairs that require breaking a pressure connection. TEST PRESSURE Both low pressure and high pressure testing procedure should be followed. Low pressure test A low test pressure in the range of 15-25 kg/cm2 (200 to 350 psi) should be carried out.. High pressure test Once the equipment clears the low pressure test, it should be tested to a pressure to be decided as explained below: On installation of the BOP stack, the test pressure should be minimum of the following: (1) Rated working pressure of the preventer stack. (2) Rated working pressure of the well head. On subsequent tests as mentioned above, the BOP stack should be tested to at least 70% of the preventer rated working pressure but limited to the least of the rated working pressure of the wellhead and 90%of the burst pressure of the upper part of casing string. However, in no case the test pressure should be less than the expected surface pressure. An exception is the annular preventer which should be tested to 50% of its rated pressure to minimize packoff element wear or damage. TEST PROCEDURE Detailed step wise procedure for pressure testing of BOP stack and other associated equipment is as under

Reference: Drilling Operational Manual/ Institute of Drilling Technology/ONGC/Chapter-15

PRESSURE TESTING OF BLIND RAMS (Fig.15.1) 1. Make up appropriate casing head test plug on top of a stand of drill collar and run-in the same on a joint of drill pipe. Set the plug in casing head seat. Back off and remove drill pipe joint. Note: Ensure that test plug size, shape and contour matches with that of casing head where it will seat. If the test plug is of open bore type, make sure that it is run-in with bull plug to isolate casing and open hole from test pressures. 2. Fill preventers with water . 3. Open all the valves and chokes on choke manifold and allow water to flow through each outlet. Flush all the lines and BOP with water. 4. Open both the valves on casing head below test plug seals to recognize leaking seal and prevent formation or casing damage in case of any leakage through test plug. 5. Close valve no.7& 9 on choke line and 2 & 3 on kill line. 6. Fill and top up BOP stack bore with water . 7. Close blind rams with 105.6 kg/cm2 (1500 psi) closing pressure. 8. Check closing line and preventer for leaks. 9. Apply pressure by cementing unit or test pump through main kill line and pressurize upto 15 to 25 kg/cm2 and hold for 3 minutes. If pressure is holding, increase the pressure upto final test pressure as decided and hold for 5 minutes. 10. Check all the valves, flanges apd seals that are under pressure for leaks and tighten if necessary. Check blind rams for leak. Check test plug for leaks. Release pressure. 11. Open blind rams with 105.6 kg/cm2 (1500 psi). Check opening line for leaks. 12. Record test results.

Fig. 15.1: Testing of Blind Ram

Reference: Drilling Operational Manual/ Institute of Drilling Technology/ONGC/Chapter-15

PRESSURE TESTING OF ANNULAR AND PIPE RAM BOPs (Fig. 15.2) While testing above elements, it is recommended that test pressure should be applied from the drill pipe to create a situation where all elements can be tested in the direction they would experience pressure during a well kick. Step wise procedure is as under: 1. From the previous test with all the lines and BOP flushed with water and the test plug seated in the casing head with a stand of drill collar, run in appropriate size drill pipe and make up with test plug. Pull out the drill pipe with test plug and tighten the joint if required. Again lower the test plug and allow it to set in casing head seat. Note: Make sure that the test plug has the integral port. If not, a perforated sub should be used with the test plug. Ensure that the casing head valves are open for the reasons discussed earlier. 2. Make necessary connections at the rig floor to pump through drill pipe with the help of cementing unit or test pump. Purge all air from drill pipe and preventer. Fill the preventer with water, if required. 3. Close valve no.7& 9 on choke line and 3 & 6 on kill line (nearest to the stack). 4. Close annular preventer with appropriate closing pressure as per manufacturer's recommendations. 5. Check closing line and annular preventer for leaks. 6. Apply test pressure through drill pipe and raise pressure to 15 to 25 kg/cm2. Hold for 3 mins. Check for any leakage. If pressure is holding, increase and the pressure upto final test pressure as decided and hold for 5 minutes. 7. Check for leaks and release pressure. 8. Open annular preventer and check opening lines for leakage. 9. Now close upper pipe ram with 105.6 kg/cm2 ( 1500 psi) NOTE: Be sure that ram size fits with the drill pipe size 10. Check closing line and preventer for leaks. 11. Again apply test pressure through drill pipe and raise pressure upto 15 to 25 kg/cm2. Hold for 3 mins. Check for any leakage. If the pressure is holding then increase the pressure upto final test pressure as decided and hold for 5 minutes. Test pressure should be limited to the pressure rating of the weakest member exposed to the test pressures. 12. Check for leaks and release pressure. 13. Open pipe rams with 105.6 kg/cm2 (1500 psi) 14. Check opening lines for leaks. 15. Test all other pipe rams in this manner by repeating step no.9 to 14. Make sure that the pipe rams size fits the drill pipe size in the well. lf not, take corrective measure and then test the rams.

Reference: Drilling Operational Manual/ Institute of Drilling Technology/ONGC/Chapter-15

Fig 15.2 Testing of pipe rams and annular BOP.

Reference: Drilling Operational Manual/ Institute of Drilling Technology/ONGC/Chapter-15

PRESSURE TESTING OF CHOKE AND KILL LINES, MANIFOLD VALVES, FLANGES AND FITTINGS ( Fig. 15.3) From the previous test with test plug seated in the casing head, the procedure followed to conduct above tests is mentioned below: 1. Choke & Kill lines and manifold fittings are flushed with water. For this purpose, close upper pipe ram and open all valves and chokes on choke-kill manifold to allow the flow of water through each outlet after flushing stop pump. 2. Close valves 3,6, 7 and 9 keeping upper pipe rams closed. 3. Apply test pressure through drill Ripe and raise pressure upto 15 to 25 kg/cm2. Hold for 3 mins. Check for any leakage .If pressure is holding, then increase the pressure upto the rating of the weakest member exposed to test pressure and hold for 5 minutes. After it is confirmed that there is no leaking through pressure lines and valves, pressure is released. 4. Next open valves 3, 6 I 7, 9 and close 2,5,8 and 10. Repeat step 3. 5. To test check valves 1 and 4, open valves 2 and 5. Repeat step 3. After this remove check valves so that other valves in the kill lines can be tested. 6. Now close valves 32, 43, 11' 12 and open valves 8, 10. Repeat step 3. 7. Open valve 43 & 11 and close valves 37, 15, 16 & 17. Repeat step 3. 8. Open valve 37 and close 36, 38, 39 on kill line side. On choke manifold, open valve 15, 16, 17 and close valves 14, 18, 21,22 and 23. Repeat step 3. 9. Next open valves 36, 39 and close valves 33, 34,35,40,41,42 on kill line side and open valves 14, 18,21, 23 and close chokes 13' 19, 20, 24 on the manifold. Repeat step 3. 10. Now open chokes 13, 19, 20, 24 and close valves 25, 26, 27 and 28. 11. Apply test pressure and raise upto 15 to 25 kg/cm2 .Hold for 3 mins. Check for any leakage. If pressure is holding, increase the pressure upto 50% of the rated working pressure of components downstream of chokes. Hold pressure for 5 minutes. After it is confirmed that there is no leakage through lines and valves, pressure is released. 12. Finally open valves 22, 25, 26, 27, 28 and close valves 29, 30, 31. Repeat step 11. 13. Check all valves, flanges and seals which are subjected to test pressure for leaks and tighten if necessary. Release pressure. 14. Record test results. 15. Install check valves 1 and 4 on the auxiliary and main kill lines respectively. 16. Remove test plug along with drill collar stand from the well.

Fig 15.3 Testing of choke-kill manifolds and valves Reference: Drilling Operational Manual/ Institute of Drilling Technology/ONGC/Chapter-15

PRESSURE TESTING OF INSIDE BOPs, KELLY COCKs, SWIVEL AND ROTARY HOSES (Fig. 15.4) While carrying out pressure testing of above items also, it is recommended that test pressure should be applied from the direction in which they would experience pressure during actual well kick situation. 1.

Pick up kelly.

2.

Make-up Full Opening Safety Valve (FOSV) on bottom of lower kelly cock

3.

Make up Inside BOP on bottom of FOSV.

4.

Make-up adopter sub on bottom of inside BOP and complete connection of test line from cementing unit or test pump to adopter sub.

5.

Apply test pressure first upto 15 to 25 kg/cm2and then raise to rated working pressure of inside BOP. Hold pressure for 5 minutes.

6.

Release pressure and disconnect adopter sub from inside BOP, disconnect inside BOP and connect adopter sub to full opening safety valve (FOSV) with test lines.

7.

Close FOSV and apply test pressure upto 15 to 25kg/cm2. Watch for any leakage. If no leakage, increase test pressure to rated working pressure of FOSV and hold pressure for 5 mins. After test is over, release pressure.

8.

Test lower kelly cock, upper kelly cock, swivel, rotary hose and stand pipe valves one by one. Applied test pressure should not exceed rated working pressure of the item being tested or the working pressure of the weakest member exposed to test pressure, whichever is less.

NOTE: Make sure that kelly, stand pipe etc. are full with liquid (test fluid) and air is not trapped in it.

15.4 Testing of inside BOP, Kelly cock, FOSV, Swivel and Rotaty hose Reference: Drilling Operational Manual/ Institute of Drilling Technology/ONGC/Chapter-15

ALTERNATIVE METHOD However, while carrying out pressure testing of above items ,an alternative method may be used as given below: This test is to be done after testing Annular preventer, pipe rams, choke and kill manifold valves etc. The sequence is as follows: 1. Rig down the connection which was made up for applying pressure from cementing unit or test unit. Keep the landing joint on test plug as it is . 2. Connect lower kelly cock on the drill pipe and close it. 3. Ensure pipe rams are closed. 4. Now apply test pressure through kill line. The pressurizing fluid would pass through perforated holes of test plug and would be communicated in closed position of kelly cock. 5. Hold the pressure for 5 minutes. 6. Release the pressure through choke Fig 15.5 Hanger plug for testing BOPs line. Similarly lower and upper kelly cocks fitted in kelly, inside BOP, fast shut off coupling and drop-in check valve, swivel and rotary hose can be tested. Attention is needed to make sure that kelly, stand pipe etc. are full with liquid (test fluid) and air is not trapped in it.

Fig. 15.6 Cup packer for pressure testing casing

Reference: Drilling Operational Manual/ Institute of Drilling Technology/ONGC/Chapter-15