1. introduction
The purpose of this outline program is to set the framework for the operations.
This programme will prepare the existing well, for a forthcoming near horizontal multilateral side-track which is due to begin immediately upon the successful completion of the abandonment.
The existing completion will be retrieved from the wellhead down to the ELTSR which is located just above the production packer. After setting the 'ML' packer and whipstock the well will be sidetracked out of the 9 5/8" casing.
Side-track
A 8 1/2" hole will be drilled out of the window in the 9 5/8" followed by a 6" hole out of the 7" liner. The kick off point was chosen in the chalk formation (as opposed to the Cromer Knoll) for reasons of improved wellbore stabilty in this intersection area. The 7" casing point has been chosen in the FU 2 2/3 which contains of reservoir sands and can easily be picked up by LWD. The mud weights will be reduced before entering the reservoir in the 6" hole section.
Hazards
The Cromer Knoll formation which overlies the Kimmeridge and reservoir is known for its troublesome shales and wellbore stabilty problems.
The Kimmeridge is a reactive shale and high mud weights are required for well bore stability.
2. preparation and background
2.1 Communication
Prior to carrying out the programme a meeting shall be held between the following staff;
Offshore Installation Manager Production Operations Supervisor Drilling Supervisor Tool Pusher Wellsite Operations Engineer Well Services Supervisor Platform Services Supervisor Other relevant staff.
The purpose of the meeting is to;
- introduce people and establish communication channels.
- discuss the programme.
- ensure that all personnel are aware of their responsibilities and the application of the relevant procedures.
- ensure that all documentation for the planned operations is on board.
During the meeting, reference shall be made to;
- the Well Engineering procedures
- well safety and the action to be taken in the event of difficulties experienced during either routine or non-routine operations.
- annular pressure monitoring procedures.
- the stage at which the next meeting shall be held.
Note : The DE shall minute the meeting and ensure that a copy of the minutes is kept on the wellfile with copies sent to xxx.
2.2 Reporting
Copies of the morning drilling operations reports shall be sent to xxx. The reports must be sequentially dated and numbered.
2.3 Wellhead and X-mas tree
The existing equipment is a 5000 psi Cameron-mas tree mated directly to a 5000 psi WP FMC FS-5 wellhead.
2.4 Reservoir data
Fulmar Reservoir pressure : Formation oil gradient : 0.32 psi/ft " " water gradient : 0.48 psi/ft
Perforations AHBDF : 11184' – 11212 11226' - 11266' 11266' - 11290' 11304' - 11316'
2.5 Geological prognosis
Formation TVsubsea Accuracy Bottom Chalk 8413' +/- 150' Bottom Cromer Knoll 9682' +/- 150'
X-Unconformity Bottom Kimmeridge 9912' -17/+32' Top Fulmar
2.6 Geological targets
Target 1: 6370604 mN 530234 mE 9912 tvss
Target 2 6370599 mN 530112 mE 10082 tvss
Target 3: 6370604 mN 529916 mE 10170 tvss
Target 4: 6370608 mN 529751 mE 10198 tvss
The lateral drilling target sizes are calculated using elipsoidal ucertainty models.
2.7 Deviation
2.7.1 Deviation data sheet
Deviation data sheet.
2.7.2 Deviation wellpath
See Appendix 6 of the Well Data Sheet.
Due to the East West direction of the well non magnetic BHA's will be required to obtain useful deviational data. A separate survey in the 7" liner will be not be required.
2.7.3 Anti-collision
There are no areas of concern for the side-track with regard to collision avoidance.
2.8 Evaluation
Mud logging : A geologist will be on site to pick the top Kimmeridge. Two sets of wet cuttings and one set of dry cuttings are required every 30'. Logging of the cuttings will assist in the early recognition of the Kimmeridge and the setting of the 7" liner as deep as possible prior to entering the reservoir. The objective is to case as much as possible reactive shales prior to reducing the mudweight in the reservoir.
Logging : MWD/GR is required in the 8-1/2" section to facilitate the picking of casing point. MWD/GR is also required in the 6" section to assist in the early recognition and correlation of the reservoir units. No logging other then LWD is planned for this well.
2.9 Completion
A separate completion programme will be issued nearer to the required time.
2.10 General
The drilling and well services BOPs, risers and lubricators should be rated to 5000psi. Ensure that the latest workshop test dates are checked.
Upon arrival on the rig all equipment should be thoroughly inspected to ensure that it is fit for the intended purpose.
In case of asphaltene deposits being encountered in the wellbore, a quantity of asphaltene dissolver (Clear 2961) should be available.
The kill weight for the brine was calculated to provide a 200 psi overbalance at the top of the tubing punch holes of 11226 'ahbdf (10169'tvbdf).
Maximum anticipated reservoir pressure = 4900 psi at 10254'tvbdf.
Assume oil gradient is 0.32 psi/ft.
Assume casing housing is at 50'tvbdf.
Kill fluid gradient = [4900 - (10254'-10169')0.32 + 200] 10169'-50' = 0.501 psi/ft.
3. detailed programme
3.1 Preparation
3.1.1 Skid rig and transfer control
Notes :
Prior to operations commencing, soak the tubing hanger tie-down bolts in penetrating oil.
Prior to the start of operations check the annular pressures and record on the DDR.
Ensure that sufficient brine is on board to fill up the hole when retrieving the completion.
The sidetrack will be carried out with Silicate mud.
1) Mix Silicate WBM as per the BHI mud programme.
2) Skid the rig over KAS-05 and take control of it from Production Operations.
3) Check the integrity of the tubing hanger seal.
3.1.2 Well kill
Notes :
Summary
At this stage the barriers in the well are;
i) Tubing and annulus filled with 500 pptf mud.
iii) A TWCV set in the tubing hanger, pressure tested to 2000 psi from above.
iv) Tubing hanger/"A" annulus seals pressure tested.
3.2 Removal of Tubulars
3.2.1 Remove X-mas tree
1) Check the condition of the tubing hanger tie-down bolts, if in poor condition change them and the chevron seals out one at a time.
Notes :
Ensure that any pressure between the tubing hanger seals and the X-mas tree P-seals has been blown down prior to replacing the tie-down bolts.
Keep the tubing hanger seal fully energised whilst all the tie-down bolts are been replaced.
2) Ensure that the X-mas tree seals have been fully de-energised.
3) Nipple down and remove the X-mas tree. Check the condition of the thread for pulling the tubing hanger and tubing. Make up the hanger pulling tool to the thread, count the number of turns for make-up. (If the thread is in poor condition a spear will be used.)
4) Isolate the control line, in order to prevent pressure bleed-off during testing the BOP's.
3.2.2 Install riser and BOP stack
1) Install an 11" 3000 psi * 13-5/8" 10,000 psi adapter flange, riser and 13-5/8" BOP stack with rams as follows (from top):
Variable bore rams (7" - 4-1/2") Blind shear rams Variable bore pipe rams (2-7/8" - 5").
2) Install a chicksan line from one of the "A" annulus outlets to a BOP side outlet (to allow fluid to bypass the hanger when circulating or lowering/pulling the hanger). Ensure that the chicksan line is tested when the BOP's are tested.
3) RIH with 5" drillpipe, BOP test tool and crossover. Make up into the tubing hanger threads. If the hanger threads are corroded or damaged it will not be possible to make up the crossover tool. Space a drillpipe tooljoint immediately under the rams being tested (in order to avoid upward movement of the string while testing).
4) Test lower rams, chicksan loop (against a closed valve) to 3000 psi and the Hydril to 2000 psi. Remove the test string. Test the blind shear rams to 3000 psi against the TWCV. Monitor the volumes pumped.
5) Run a drift through the BOP stack and riser to ensure clear passage for pulling the tubing hanger/seal assembly.
3.2.3 Recover TWCV
Run in and retrieve the TWCV.
3.2.4 Recover tubing
Notes :
Recover tubulars as per Procedures
It is not anticipated that radioactive scale will be encountered during the recovery of these tubulars, however, precautions should be followed as indicated above.
A Schlumberger tubing cutter should be onboard as a contingency.
1) RIH 7" landing joint and engage with the hanger threads (chain tong tight), count the number of turns. Alternatively, if the tubing hanger threads are damaged RIH with a 7" casing spear. Back out the tubing hanger tie-down bolts fully to permit pulling of the hanger.
2) Unseat the tubing hanger and shear off the extenda joint from the slick joint assembly.
3) Pull back to rotary table, observe well and if required carry out one circulation.
4) If the well is static or losses are less than 20 bbls/hr., POOH and L/D the tubing whilst keeping the annulus full with brine. Observe closely for overpulls which may indicate the loss of control line clamps. Maintain tension on the control line while pulling to give an indication of control line integrity.
Record the number of control line clamps recovered on the DDR. The total number of control line clamps installed when the well was completed in Sep. 1982 was not recorded.
Number all of the joints sequentially as they are pulled out of the well with water proof paint. Inspect all joints visually and report the tubing condition. Any joints with obvious defects should be bundled separately and noted in the DDR.
Note :
Ensure that an adequate number of protectors are on site.
3.2.5 Install wearbushing
Install the wearbushing.
3.2.6 Clean out trip
1- RIH with clean out assembly (hedgehog scraper included).
2- Scrape packer setting interval and clean out casing to top of ELTSR stump.
Note: If brine has a detrimental effect on the packer rubber elements the brine may be changed out to silicate WBM at his stage, prior to setting the 'ML' packer. If the preferred fluid for setting the packer is brine the well may be changed out to mud prior to milling out the 9 5/8" casing. Baker to confirm.
3.3 Packer Setting and orientation
3.3.1 Pre-Job
For adequate back-up, equipement on board should include the following;
2 x anchor packer/whipstock assembly
2 x starter mill
1 x running tool
3 x window mill combination
crossovers from mills to drill pipe back to collars
crossovers from mills to collars
redress kit and tools for by-pass
redress kit for running tools
spare shear bolts
taper mill
Baker size 20 setting tool
3.3.2 Packer setting depth
The packer setting depth is +/- 7976 ft tvd bdf (9000 ft ah bdf). This is 626 ft tv above bottom chalk and 771 ft above top ELTSR stump.
Determine the packer setting depth in relation to casing collars. Ideally set the bottom of the packer 5-10 ft above a collar to give sufficient blank casing between top of window and next collar up. The position of the permanent packer must allow that +/- 15 ft window is milled without milling a coupling. This window must allow the side-track to kick off at 9000 ft ahbdf as per Baker KA-05ML1 revision D.0 proposal. The whipstock face will be set 30 degree from high side. Baker, Tool Pusher and the DSV to confirm the packer setting depth and whipstock orientation.
3.3.3 Packer setting
1- Run in hole with ML packer BHA consisting of the following;
Old ELTSR without seals.
5.5" tubing to space out to packer setting depth.
Baker model "AOR" bottom no go seating nipple (plug and prong installed)
Baker crossover sub
Baker Millout extension
Baker model "ML" whipstock packer (large bore)
Baker model "ML" orientaion anchor seal assembly
2- Set 'ML' packer hydraulically as per BHI procedures (to be issued). Check the packer is not set across 9 5/8" joints connections.
3- Shear off orientation anchor seal assembly with +/- 50 Klbs overpull and POOH.
4- RIH MWD tool on drillpipe, or gyro survey tool on wireline (drillpipe to be rabitted), to confirm the postion of the locating key. BHI to confirm.
3.4 Mill 9 5/8" window
Note :
Constant observation and recording of the steel recovery rate versus the milling rate is required.
1) RIH with BHI Window Master Assembly (integral whipstock) with orientation anchor. Align whipstock anchor to required direction on surface prior to running in hole.
2) Latch into ML packer with orientation anchor and Window Master Assembly and check engagement by taking overpull.
3) Mill ream window and 10 ft of formation and carry out leak off test as per seperate BHI procedures (to be isued)
The start of the window should be made approximately 10-15' above a casing collar in cemented casing. This will reduce the risk of the premature backing o ff of a short stub of casing.
1. M/U the assembly and test the section mill (dry torque all connections).
2. At cutting depth rotate at 80 RPM and record the torque. Bring up the pumps slowly - 80 SPM should be sufficient. When the strokes and pressure is established maintain them without surging until the cut is complete. The cut generally takes between 15 and 30 mins. A pressure drop of approximately 250 psi will be observed.
3. When the pipe is severed, continue rotation, gradually increasing both RPM and SPM until the desired milling parameters are achieved.
4. After 10-20 mins. or once the torque reduces to close to the initial free rotating value, start adding weight to the assembly.
5. Mill approximately 5-7', ensure that steel returns are observed at surface and check the window length. To do this stop rotation, pick up the string to the top of the section where an overpull should be observed. Lower the string and set down weight on the casing stub.
A further check is to stop the pumps whilst continuing circulation to equalize the pressures. Stop rotation then pull the string up into the casing approximately 4-5'. Engage the pumps at 80 SPM and slack off into the section, a pressure drop of approximately 250 psi should be seen. Continue to slack off until the down weight is set on the casing stub.
Note : A constant observation and record of steel and cement recovery must be maintained.
4) POOH and check mill gauge and condition.
3.5 8 1/2" hole section
Notes :
The 8 1/2" section is planned to T.D. at 10236'tvbdf (11710'ahbdf).
Refer to the Mud program (to be issued) for details on the parameters required for the mud and hydraulics for this hole section.
Avoid pumping whilst passing the bit and motor through the window to avoid flipping over the motor as a result of reactive torque. The chance of creating a washout is also reduced.
3.5.1 Drilling 8 1/2" hole
1) M/U the 8 1/2" drilling assembly comprising 6 3/4" Navi-drill, UBHO, MWD etc using non mag DC's.RIH to the top of the 9 5/8"" casing window.
2) Perform the kick-off with the toolface set to the high side.
3) Drill ahead to section T.D. at 11710 'ahbdf.
4) Make wiper trips when required.
3.5.2 Retrieve Whipstock
1- RIH with BHI retrieving hook and MWD. BHA to be advised by Baker. Orientate hook and commence pumping (hook should fall in position).
2- Attempt to latch into whipstock slot and pull slowly to confirm engagement.
3- If engagement confirmed pull to 50 Klbs to unlatch orientation anchor from 'ML' packer.
Note: if after two runs the whipstock cannot be latched on, the die collar overshot will be used to retrieve the whipstock.
3.5.3 Run 'guidestock'
Run the short guidestock with orienation anchor as per Baker procedures.
3.6 Run and Cement 7" liner
3.6.1 Liner equipment
1) Liner string Float shoe Two joints of casing for the shoe track Float collar Joints of 7"/29lbs#/13%Cr/L80/VAM to 8980' (20' inside 9-5/8" ).
N.B. Install one flexible centralizer per joint - shoe track = ?? - open hole = ??
2) Liner hanger sub-assembly
HR Running tool 5" HWDP 5" DP to surface
Note: 13 Cr liner hanger to be onboard as contigiency.
3.6.2 Liner running and cementing procedures
Notes:
Run the liner as per GUIDEX>Procedures>Casing and Tubing>Liner Preparation and Running.
Cement the liner as per GUIDEX>Procedures>Cementing>Liner cementing procedures.
Perform a check trip with all of the 5" HWDP required for running the liner and circulate at least 2 times bottoms up and POOH.
Before entering open hole with the liner, stop and break circulation to condition the mud by reducing its viscosity.
Use a 5 % open hole volume excess for the cement volumes.
Refer to the Lead contractor cementing program for recipe's
Always use a Halliburton "Tru-weight" balance and not a Baroid mud balance to monitor the cement density.
If the batch tank is unable to accommodate all of the main slurry then the recipe excess may be mixed and pumped conventionally prior to pumping the slurry from the batch tank.
1) Run the liner assembly to above the 8-1/2" section TD. Slight adjustment may be required to allow the top of the liner to be spaced out such that the liner protrudes in the 9 5/8" casing and the flush pipe is across the intersection for future cut-off.
2) Batch mix the scavenger slurry as per the drilling programme cover sheet in the batch tank. The scavenger slurry should fill 500' of 9-5/8" casing with the drillpipe removed.
3) Pump 250' equivalent of the scavenger mixwater (i.e. no silicalite).
4) Pump the scavenger slurry.
5) Weigh up the remainder of the scavenger slurry to the weight required for the main slurry.
6) Pump the main slurry.
7) Release the HR running tool as per Baker and circulate out the excess cement conventionally. POOH with running tool.
3.7 6" hole section
Notes :
The 6" section is planned to T.D. at 10352'tvbdf (12903'ahbdf)
Refer to the Mud program (to be issued) for further details on the parameters required for the mud and hydraulics in this hole section.
Carry out the leak-off test. Fax the results (including graphimmediately following the test.
3.7.1 Drilling 6" hole
1) M/U the 6" drilling assembly comprising of a 4-3/4" Navi-drill, LWD etc including non mag DC's
2) After drilling 20' of new formation carry out a leak-off test.
3) Drill ahead to section T.D. at 12903'ahbdf. The T.D. may be subject to change if Target 1 comes in different then prognosed.
4) Make wiper trips when required. POOH.
3.7.2 4.5" slotted liner
Run slotted liner as per Baker procedure
Completion
Appendices
ANTI-COLLISION DATA SHEET
Definitions : Generic MD & TV = Ft.AHBDF and TVDBDF of the well being drilled i.e. KA 05s1 Check MD = Ft. AHBDF on the stated check well where the S.F. is lowest for the given generic well MD. ROU = Radius of uncertainty; C-C = Centre to centre separation; the closest distance between the stated generic MD and the check well as calculated by 3-D closest approach. I.B. = Inter-boundary distance; the distance between the boundaries of the uncertainty spheres of the generic and check along the C-C line. S.F. = Separation Factor. S.F. = (C-C)/(GenericROU + CheckROU).
MUD AND HYDRAULICS
The mud properties given on the front page of the drilling programme are preliminary. Final properties are given in the mud programmes;
General notes
Circulate the complete hole clean before wiper trips.
Do not start to trip until the hole is clean. All tripping in new hole should be performed whilst pumping at half the rate as when drilling.
It is imperative to have full circulation before attempting to pull out of hole. Before breaking off each stand always go down 30' with circulation to establish some free hole beneath the bit and to establish that the BHA is free and not packed off.
At the first sign of packing off (reduced flow rate and increased pump pressure), cut back the pump rate slightly and go back down. Do not continue to POOH. Continued pumping whilst pulling out may be accompanied by a reduction in apparent drag,. This should not be interpreted as the string coming free but rather that the assembly is being hydraulically pumped out of the hole. Continued pulling out of the hole will exacerbate the problem.
Once the assembly has been run back down beneath the cuttings, gradually increase the pump strokes to the previous rate and come up again. It is imperative to have full circulation before attempting to pull out of the hole. If unable to go down, do not on any account jar up. Jar down if possible, pick up the kelly and try to work free with rotation until the string becomes free.
Whilst drilling a horizontal hole procedures must ensure effective hole cleaning in order to reduce the risk of stuck pipe. Effective hole cleaning can be achieved by combining BHA, mud system and hydraulic designs with sound cuttings removal procedures. Tripping procedures and intervals are to be developed as the hole is progressed to take account of the lack of a top drive.
The formation of cuttings beds on the low side of an inclined or horizontal hole can be identified as a common cause of stuck pipe. To reduce the build up of cuttings beds the annulus must be kept in an agitated state. The use of the following practices will help to achieve this :
1) Use the circulating elevator to pump out of hole on all trips, if necessary pick up the kelly and rotate the string (extreme care has to be taken to prevent side-tracking the hole).
2) Closely monitor the drag and torque as a means of providing an early indication of the formation of cuttings beds.
3) Closely monitor the quantity and quality of the cuttings returning at the shakers, particularly at the bottoms up of any viscous pills.
4) Carry out check trips every 300'-500' in the 8-1/2" hole and every 200'-300' in the 6" hole or more frequently if conditions dictate that cuttings beds should be cleared.
5) Use low viscosity brine sweeps to agitate and remove possible cuttings beds.
It is NOT recommended that a high viscosity pill follows the low viscosity pill because of the detrimental effect they have on the mud properties.
Great care must be taken to fully circulate the hole clean prior to the use of such pills because the low viscosity pills can be so effective at agitating the cuttings that a packed -off annulus can result if excessive volumes are pumped.
6) During tripping it is recommended to use coarse CaCO3 for heavy pills instead of baryte.
Hydraulics calculations
The following hydraulics figures have been supplied by Baker Hughes Inteq for the
8-1/2" and 6" hole sections.
DRAG AND TORQUE
Baker Hughes Inteq have carried out a drag and torque analysis.
Assumptions
The following assumptions have been made for the drag and torque calculations.
General
Wellpath = Mud weight = Bit torque = Depth =
Friction factors
A study was undertaken during the drilling of the 6" hole section on AA-04S2 to determine the friction factors. The back calculated friction factors were;
Cased hole = 0.15 - 0.20 Open hole = 0.20 - 0.30
The high end values are thought to have been due to a cuttings bed build up, since the back calculated values reduced significantly following a wiper trip.
Friction factors used in the calculation were,
Cased hole = 0.20 Open hole = 0.25
Bottom hole assembly
6" bit 4-3/4" Navi-drill, PDM c/w 5-7/8" UBH stabiliser 5-1/2" stabiliser MWD 2 * NMCSDP 3-1/2" HWDP Jar 3 * 3-1/2" HWDP 5" DP (19.5 pptf, S135) to surface
CONTINGENCY AND RISK ANALYSIS
the major potential problem areas with their associated risked costs are set out below.
Note :
COST AND TIME ESTIMATE
GEOLOGICAL FIGURES