1 Objective
Drill 8 1/2" hole to 15316 ft, run a lookahead VSP, drill 8 1/2" hole to ± 15581 ft (85 ft above the "x" marker, run logs and set the 7" liner .
2 General
1. The actual depth of the liner shoe will depend on the results from the lookahead VSP, and other information available at the time, to ensure a shoe integrity which is adequate for drilling the next hole section with a sufficient safety margin when using a maximum anticipated mud weight of 985 pptf. The 8 1/2" hole TD criteria is 85 ft above "x" unconformity marker as derived from the VSP.
2. All BHA's to be run should be checked using MGI Wellplan for critical rotary speed/drill string vibration analysis.
3. The mud used for this section will in effect be the same mud as used previously. During the latter stages of drilling this section the mud will be treated with HT additives to upgrade the specifications.
4. The programmed mud weight initially of 880 pptf has been chosen for the LOT. The mud weight for drilling ahead will be determined by the LOT.
5. Refer to the HPHT drilling procedures. All operational staff to be fully aware of these procedures.
6. A leak off test with downhole gauges will be performed with 880 pptf mud at the 9 7/8" shoe.
7. Care should be taken not to induce losses. Surge pressure calculations will be made available and running speeds adjusted accordingly. ECD's and hydraulic calculations will be made available prior to drilling ahead.
8 Ensure ditch magnets are installed. Monitor metal recovered every 12 hours. Rotating hours and revolutions should also be reported. If casing wear is a concern or any unusual trends exist MFCT run may be considered.
9 Ensure that all wireline, pressure control equipment and HPHT contingency equipment such as survey retrieval instructions, free point tools, back off shots and severing tools (Hot Forge DCC's) are on board prior to drilling out. Check that explosives provided are recently manufactured.
10 HDIS and circulating subs should be included in the BHA's
11 Casing protectors shall be available for use after the first bit run.
3 Drill 8 1/2" Hole
1. RIH with rotary drill out assembly. Tag and drill cement to 10 ft above the 9 7/8" shoe, increasing the mud weight to 880 pptf. Report TOC on the daily drilling report.
2. Take SCR's and choke and kill pressure drops.
3. Drill out remaining cement, float equipment, rathole and 10 ft of new formation. Report shoe depth on the daily drilling report.
4. Circulate and condition mud if required and pull back into the casing shoe. Rig up and run surface read out pressure/temperature gauges to perform a leak-off test.
5 With the gauges in the string, pull back a stand at various rates to record swab and surge pressures. Perform circulation rate tests to monitor bottom hole pressure changes with flow rates (ECD). Recover gauges and rig down Schlumberger.
6 Drill 8 1/2" hole to 14000 ft.
7 POOH
8 Pick up MWD and install drill pipe casing protectors. RIH.
9. Drill 8 1/2" hole to 15316 ft. Take MWD surveys every 100 ft . If the MWD fails a MSS may be considered
10. Circulate and condition the mud to clean the hole. POOH. Run and lookahead VSP.
11. Drill 8 1/2" hole ahead to section TD which will be based on the lookahead VSP and other information available at the time. Maximum section TD is to be 85 ft above the "X" unconformity marker as derived from the VSP. MWD/GR will be used below VSP point.
12. At section TD circulate the hole clean, if hole conditions indicate, make a wiper trip prior to POOH.
13. Run electric logs.
14. If necessary, perform a wiper trip prior to running liner.
4. BHA
ROTARY ASSEMBLY NO. 1
- 8 1/2" Bit
- 1 x 8 1/2" Near Bit Stabiliser
- 1 x 6 3/4" Pony Drill Collar
- 1 x 8 1/2" Stabiliser
- 1 x 6 3/4" Drill Collar
- 1 x 8 1/2" Stabiliser
- 3 x 6 3/4" Drill Collar
- 1 x 8 1/4" Stabiliser
- 2 x 6 3/4" Drill Collar
- 1 x 6 3/4" Jar
- 1 x 6 3/4" Drill Collar
- 6 3/4" HWDP
ROTARY ASSEMBLY NO.2
- 8 1/2" Bit
- 1 x 8 1/2" Near Bit Stabiliser
- 1 x 6 3/4" Pony Drill Collar
- 1 x 8 1/2" Stabiliser
- 1 x 6 3/4" MWD
- 1 x 8 1/2" Stabiliser
- 3 x 6 3/4" Drill Collar
- 1 x 8 1/4" Stabiliser
- 2 x 6 3/4" Drill Collar
- 1 x 6 3/4" Jar
- 1 x 6 3/4" Drill Collar
- 6 3/4" HWDP
5. Mud properties
- Mud Type : Ultridrill POBM
- Mud Weight : 880 - 960 pptf (final weight dependant upon LOT)
- Plastic Viscosity : < 90
- Yield Point : 28 - 22 lb/100 sq ft
- Gels : 12/30
- HPHT Fluid Loss : < 4 MLS/30 min
- (at 300 Deg F)
- LGS : <6 %
- Water Phase Salinity : 180 - 220k mg/l chloride
- Pseudo/Water Ratio : 80/20 - 90/10
- Excess Lime : 3 ppb
- Electrical Stability : 750 volts