Casing & Tubing Positive and Negative Tests
Contents:
Inflow Testing Procedure
Procedure for Circulating to Lighter Fluids (Diesel etc.)
Interpreting Inflow Test Results
TOP OF 7” LINER - INFLOW TEST PROGRAM
Prejob operations
Operational Steps
7” Liner Contingency Planning
Unable to reach setting depth with liner
Liner setting Ball doesn’t seat
Liner setting Ball seat doesn’t shear
Liner running tool doesn’t release
Liner Plug does not bump
Losses are observed during liner cement job
Liner Packer setting dogs do not engage top of tieback extension
ZXP Liner top packer fails positive pressure test
ZXP liner packer setting procedure
Inflow Testing Procedure Inflow tests are generally carried out to verify if there is communication with the formation through the casing, a liner lap or past a cement plug (bridge plug). Most of the applications are in connection with testing or squeezed off perforations and casing leaks, testing liner-laps, float shoes and float collars, cement plugs and bridge plugs. An inflow test is performed by reducing the hydrostatic head above the item to be tested by circulating to a lighter fluid.
Procedure for Circulating to Lighter Fluids (Diesel etc.) 1. RUN retrievable packer with circulating valve, safety joint and short tail on drillpipe, to depth to be advised by Operations Engineer. 2. SET retrievable packer at advised depth and test annulus with 1000 psi in order to check that packer is properly sealing and that the tool assembly is functioning properly before RIH any further. 3. Generally, the retrievable packer should be set at some 50 ft above the interval to be tested (or 50 ft above TOL) in order to minimise any possible influx. OBTAIN prior approval from the Head of Onshore/Offshore Operations for inflow testing during the hours of darkness. 4. CIRCULATE the drillpipe to a lighter fluid until the required drawdown is accomplished. (An air cushion may be used) 5. After having circulated the well to achieve the required drawdown, PERFORM the inflow test on the well for 15minutes as detailed in the Drilling Programme. 6. REVERSE well to completion fluid. 7. UNSEAT retrievable packer. CIRCULATE and OBSERVE well dead. 8. POOH and L/D retrievable packer.
Interpreting Inflow Test Results The “Horner Plot” method should be used for interpreting inflow tests to confirm the integrity of liner laps for over pressured gas wells. Traditional methods are often ambiguous and require unnecessary long rig time. Traditional Interpretation method. The mechanical integrity of e.g. liner laps can be tested by creating a underbalanced situation over the zone of interest. This is usually done by displacing the well to water. Once the well has been displaced to water, the fluid returns are monitored for a duration of say 4 hrs. This back flow from the well is caused either by thermal expansion, or an influx into the well bore (leak) and thermal expansion. The observed flow rates are plotted against a time scale allow to determine if the situation is one with both an influx and thermal expansion or with temperature effects only. In order to positively determine whether and when zero flow will materialise, the inflow test has to be conducted for much longer than 4 hours.
TOP OF 7” LINER - INFLOW TEST PROGRAM Well Current Status Data: 8 ½” hole depth 3850 m MDRT. / Mud Weight 1.41 SG. 7” Liner Data: Weight: 32 lbs/ft. /Grade: P-110. /Thread Connection: Tenaris Blue/ 7” Top of Liner 3004.91 m MDRT. 7” Shoe 3579 m MDRT.
Prejob operations Prior to start the jobs for the inflow test, it is neccesary to scrape the 7” liner and the 9 ⅝”·casing. These operations shall be done in two different runs. Even though all of these operations can be done in a run, it is advisable to do in two different runs, so a proper dressing of the PBR can be achieved.
The first run will comprise the polish of the 7” Liner PBR. Check and inspect all the BHA components, as well as all the neccesary cross overs are on location and in good shape. The BHA to use is as follow (lengths are only indicative and must be taken as a reference, the final BHA to be done and submitted to town to be checked).
Run in hole with the previous assembly. Scrape 9 ⅝” casing from 2,600 m to 3,000 m. Dress PBR as per Baker Engineer Instructions. POOH with this assembly. M/U the following assembly: RIH and scrape 7” liner from 3,020 m to 3,540 m. Tag TOC inside the 7” liner (or landing collar). Report depth in DDR.
NOTE: The intervals to scrape are indicative. According to Well Testing & Reservoir needs this might change. If this happened to be, then the intervals will be communicated to the rig site.
POOH with the scraper assembly. Prepare for the cased hole logging operations. After logging, prepare for the inflow test.
Operational Steps 1.
Pick up tools as per instructor operator. Program memory gauges to measure each 5 seconds.
2.
RIH testing string as per following schema (to be validated with Halliburton Engineer):
3.
Run in hole +/- 30 meters of 6 ¾” Drill Collars (3 stands) + 1,670 meters 5” drillipe filling up every three to five stands. Trip tank to be used.
4.
When 1,700 m in hole, stop filling up, because 1,700 meters are required in order to get 2,500 psi differential pressure at RTTS packer. Continue running in hole 5” drill pipe without filling up.
5.
Packer depth must be 2,995 m MDRT (according to logs 9 ⅝” casing couplings are at 2,987.5 m MDRT and 3,000 m MDRT). Run packer down to one meter deeper and then pick up in order to be able to set RTTS packer.
6.
Once the string is in tension, turn string the required amount of right–hand turns and slack off weight to set RTTS packer. The amount of weight neccesary is 11.5 Tons. Wait until hydrospring valves open.
7.
Once set, ensure packer is completely set by pressuring up the annulus. Hold pressure for 10–15 minutes.
8.
Always record weight applied on tool, the time it takes to open, and the estimated bottomhole temperature every time hydrospring valve is run. An indication of valve opening is erratic fluctuation in the martin decker weight indicator. Note: In case of valve not open, pick up the string weight and set back down.
9.
DO NOT Register with the weight bar level to see whether a drop or rise in the fluid level inside the drillpipe. The slick line in the rig does not work, so it is not suitable for this. The result of the inflow test will be determined once the memory gauges are at surface.
10. Monitor well during 5 hours. 11. Close hydrospring valve by picking up the string. Fill up drill string and continue pressurizing until breaking the disc in the pump out reversing sub (check and record pressure value to break the disc with Halliburton operators). Note: if unable to break the disc with pressure, drop the bar to break the pins and open the pump out sub.
12. Circulate reverse 1.5 Volume of the drill pipe string until system gets homogeneous. 13. Unset RTTS packer, putting the string in tension and then turning the drillpipe to the left. 14. Record any returns from the annular before start pulling out the hole the string. If returns observed, continue circulating through the pump out sub until no returns are observed. 15. POOH and lay down Halliburton equipment. 16. RIH with 3 ½” + 5” Drill pipe to bottom of 7” Liner (3579 m MDRT) with OEDP. 17. Displace hole to 1.26 SG Brine. 18. POOH and rack back drillpipe.
All the packer and running calculation must be validated at rigsite.
7” Liner Contingency Planning; Unable to reach setting depth with liner The liner hanger starts to set at approximately 1,400psi / (100 bar) differential pressure. Take care that circulation pressure does not exceed 900psi / (62 bar). If it takes more than 900psi / (62 bar) pressure to circulate. Make sure that the Liner hanger is in tension before increasing the pump pressure above this value. To wash liner through a tight spot the following steps are to be taken: 1. Pick up string. 2. Start circulation and check weight of string up and down. Watch pressure closely (keep somebody regulating the pump). 3. Slowly start rotation. When circulation is established slowly lower string through the tight spot, making sure that circulation pressure stays below 900psi / (62 bar) pressure. Watch pressure and torque readings carefully. 4. Do not slack off more than 40 Klbs (20 Tonnes) onto liner weight while rotating. If slack off weight is reached, work string up and down through tight spot and continue.
Liner setting Ball doesn’t seat 1. Drop the Bronze ball 2. Rapidly fluctuate the pump pressure to generate pressure surges at the ball seat. 3. Set mechanically on bottom.
Liner setting Ball seat doesn’t shear 1. Go to 80% of casing burst pressure = 8,500 psi / (600 bar) 2. Pressure up and bleed off over 10 cycles 3. Prepare a Contingency plan that should consider these main operations:
POOH and drill out shoe track. Cement through the shoe with cement retainer or retrievable packer with a packer setting dogs sub higher in the string. Consider setting ‘ZXP’ Liner Top Packer on a second trip using modified Packer Setting if scan liner is not run .
Liner running tool doesn’t release 1. Ensure tool is in compression of 20 klbs (10 tonnes) minimum when putting in turns and repeat left hand rotation cycles. 2. Maintain left hand torque and work pipe between maximum string up weight (before hanger was set) and set down weight (after hanger was set) 3. Continue working pipe while reciprocating. 4. Leave workstring in tension and circulate. 5. If nothing is solved, prepare a contingency plan that should consider these main operations: Chemical Cut on DP Fishing
Liner Plug does not bump 1. It is important to ensure cement is not left within the latch couplings. 2. Stop pumps at agreed displacement (e.g. 75% of total shoe track volume) and release setting tool. 3. Pick up workstring and set ‘ZXP’ Liner Top Packer as per procedure.
Losses are observed during liner cement job
Reduce flow rate (considering Thickening time). Set ZXP Liner Packer anyway and continue as per programme.
Liner Packer setting dogs do not engage top of tieback extension
Pick up workstring to point where dog subs are exposed above the tieback extension. Set down again. Pick up workstring and rotate drill string to free any cement from around dogs. Set down again. If engagement is still not possible, circulate to clean dogs. Re attempt to set. Still no success. POOH, Set ZXP Liner Top Packer on second trip with modified Packer Setting Sub or tie back packer if scab liner is not run.
ZXP Liner top packer fails positive pressure test
Attempt to fully set packer on second trip with modified Packer Setting Sub. If pressure test is negative and leak at liner top is suspected, a contingency liner top isolation packer will be installed if scab liner is not run. Separate detailed procedure for this contingency operation will be prepared in due time.
ZXP liner packer setting procedure 1. Pick up +/- 3m to locate mechanical setting dogs on top of Tieback Extension. 2. Slack-off minimum 10 Klbs (5 tonnes) and mark the pipe. Continue to slack off weight for a minimum of 50Klbs. Monitor weight indicator for shear indication (two shears may be observed). Hold for 5 minutes to ensure complete setting of packer. 3. Pick up to up weight and set down 10Klbs. Observe mark on pipe. If mark has moved down approx 9”, this is an indication of the packer functioning. 4. Do not perform any annular pressure test at this stage. 5. Pressure up drill pipe to 500 psi (35 bar) and pull running tool inside PBR and Long Way circulation whilst inside the PBR. NOTE: String to be pulled slowly due to observe the pressure loss to indicate the RPB pack off bushing has been retrieved from ‘RS’ seal bore. 6. Lay down plug dropping head and POOH.
