Drilling 16” Vertical Hole Section Good Procedure
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The key objectives of this section of the well will be to optimize penetration rates, keep the hole as vertical as possible and to protect the Water Zone while achieving the goal of lowest cost per meter. Two (2) pumps at minimum should be utilized to drill this section, as well as having large liners (7″) installed. With PDC bits, the section requires the use of up to 1,000 gpm flowrates from drill out to casing point. More consideration shall be paid to the types of drill pipes used. The jets of the bit should be dressed accordingly . The penetration rate is to be kept as high as possible dependent upon the capability of the solids control system, hole cleaning, and hole conditions.
Consideration should also be given to making high viscosity sweeps of the hole as necessary to keep the annulus from loading up with cuttings. Wiper trips are to be made on an as needed basis, rather than a regular time interval.
Mud weights as high as 11.4 ppg have been utilized while drilling this section due to possible shale cavings from the Cenomanian and pore pressure from the Albien. It is believed that 10.5 to 10.8 ppg will be an adequate mud weight through this hole section to casing point. It is desired to keep the mud weight as low as possible in order to reduce any risk of lost circulation and to maximize penetration rates. However, rig personnel should be aware of the situation and a kick drill should be held prior to drilling in the Albien.
Unless deviation is critical, there will be only one survey at TD with multishot since directional work is not normally attempted in this section.
Generally only one bit will be required to drill this hole section. Additionally, a bit will often be able to be used for two wells. All equipment should be ordered via FR and confirmed for availability. Prior to reaching 13 3/8” casing point, confirm setting depth which is currently set at 20 meters into the Dogger Lagunaire.
13 5/8” BOPE should be stump tested during this hole section so that any failures can be repaired prior to nipple up.
Ensure wear bushing is installed. Pick up bit, BHA and run in the hole. Tag cement above the float shoe; record tag up depth. Test casing to 1500 psi for 30 minutes. Displace hole to a light weight oil based mud with tight filtration controls.
Drill out shoe and 3 meters of new hole using low WOB and reduced pump rates. Circulate and condition mud. Pull the bit into the casing and perform a Formation Integrity Test (FIT) to 13.5 ppg EMW using mud pump. If FIT is not obtained notify Drilling Engineer and Drilling Manager.
Control drill until stabilizers are below the shoe utilizing a light weight oil based mud with tight filtration controls. Once stabilizers are below the shoe drilling parameters can be increased to optimize ROP.
Continue drilling to casing point, a minimum of 20 meters into the Dogger Lagunaire. The exact casing point will be specified in individual well prognosis.
Note:
Turonian formation has been giving us some problems and even sticking drill string. Historically after working pipe across the formation by reaming and/or wiper trip the problem stops through TD of the section. Reaming and/or wiper trip across it is strongly recommended.
Short trips at approximately half way of the hole section or whenever the hole condition dictates.
Upon reaching casing point circulate bottoms up, make wiper trip as necessary, drop multi shot survey and POOH while SLM. LD Stabilizers & 9½” drill collars.
Note:
At present no logs are being run on this section with the exception of an Schlumberger CBL which is run after completion of drilling operation on the P2 hole section. Any changes to this program will be identified on the individual well programs.
Rig up and run the 13 3/8” P1 protective casing string as follows:
Note: This procedure assumes the 13-3/8″ casing will be cemented utilizing Litecrete for a single stage job.
PDC Drillable Float Shoe – Up Jet, Single valve (Installed on bottom of first joint and thread locked)
2 joints 13 3/8” Protective Casing (thread locked)
NR PDC Drillable Non-rotating Float Collar – Single valve (Installed on bottom of third joint and thread locked)
13 3/8” P1 Protective Casing to surface
Centralizer Program:
Run 1 Bow Type Centralizer 2 m above the shoe.
Run 1 Bow Type Centralizer 2 m below the float collar.
Run 1 Bow Type Centralizer one every third joint across collars until 50 m below base of Albien interval.
Run 1 Bow Type Centralizer every other joint to 20” casing shoe.
Notes:
It will become SONARCO standard practice that prior to the cement job the mud pump displacement be checked and recorded. All lines and valves related to the job should also be checked and recorded. Pressure test from mud pump to cement head to ensure no fluid can bypass back to the pit. Isolate suction pit and return pit and check pit level while displacing so that a positive measurement of pump displacement and return volume is possible.
Verify that the float shoe and float collar are free from debris.
C. Clean threads and ensure casing drift is satisfactory for next hole section
Threadlock the shoe, shoe track joints, float collar, and the next box above the float collar. Increase the normal make up torque to allow for the increased friction on the thread locked joints. (usually 1.5 times normal)
Note :
Due to high friction factor for thread lock (±1.5) occasionally had difficulty to have proper make up, therefore, a practice to smear thread lock while making up pipe is acceptable.
Ensure casing is torqued to proper makeup. The box should be made up to with in 0.2” of the base of the triangle and the apex of the triangle or base of triangle +2 turns/-1 turn within the prescribed torque range.
NOTE :
Mark the triangle with yellow/white paint if available for easy identification.
Joints that are questionable as to their proper make up, with regard to previous base line torque established and its triangle stand off, should be looked more closely, if necessary they need to be unscrewed and laid down for further inspection.
Use Bakerseal thread compound, (FF = 0.7 ).
Fill the casing as it is being run and check the float equipment for proper operation after making up the float joints, and after the first joint above the float collar. Observe returns at the flow line to verify float equipment operation.
Casing specs will be provided in well specific programs and can be found in the Casing Section of this program. (if different than standard)
Ensure that the proper casing swage (c/w Lo-Torque valve) is on the rig floor while running the casing (Dowell Supplied).
Do not rotate the casing as it is being run.
Run the casing to bottom, placing centralizers as per the centralizer program. Fill the casing while picking up each joint (however don’t wait). Completely fill the casing every 10 joints. Tag bottom and pick up to setting depth, checking strap calculation. Land casing with the shoe off bottom. Ensure that no casing coupling is at or near the casing hanger landing position of the wellhead.
Rig up the cementing if losses occur- these must be cured before starting the cement job head and circulate at least one complete hole volume. Mud densities in and out must be equal and the shakers clear of cuttings and debris. During circulation, reciprocate the casing, if operationally feasible. Consider surge and swab effects in making all reciprocation decisions on frequency and length of reciprocation cycles. Pressure test all cementing equipment and lines to 3,500 psi. While circulating hold an operations/safety meeting with all relevant personnel.
NOTE: Dowell is to provide a two plug cementing head. See Cementing Section for details.
Mix and pump spacers and cement as per the recommended cementing program. The lead slurry will be generally 12.2 ppg LiteCrete cement and tailed with 15.8 ppg “G” cement as per cementing section. Use Non-rotating plugs. Top of cement planned 100 m inside 20” shoe utilizing 30% openhole excess (or 20% over caliper if run). and top of tail cement planned to top of Malm formation
Note: Cement isolation of Albien will be critical.
Displace the cement with the rig pumps. Slow pumps before bumping the plug. Iif possible, bump the plug with 2,500 psi and hold for 30 minutes to test casing. If the pressure bleeds off, DO NOT ATTEMPT TO RE-APPLY IT, in case the plugs are bypassing which will mean the cement will be overdisplaced[1]. Check float operation by releasing pressure on the casing. If the floats are not holding, pressure casing to plug bump pressure and wait on cement until surface samples have set hard in a heated place (water bath at 150 deg F). If plug does not bump at calculated displacement considering pump efficiency, do not over-displace by more than ½ of shoe track volume.
Note : If the plug does not bump, the casing will be tested later prior to cleaning-out the shoe track.
After cementing operations are complete, W.O.C. if necessary, then lift surface BOP stack and land casing with 100% final cemented hanging weight. Do not slack-off or tension casing.
Rough cut casing string, RD surface casing BOPE, final cut casing string and NU Thru-Bore wellhead equipment. NU 13 5/8” 5K BOPE, choke and kill lines, etc.
Pressure test seals as required refer to REB Testing Standards Sheet. Test wellhead assembly to 70% of casing collapse or 2500 psi, whichever is less. Make up the BOP test plug, ensure the lower annulus valve is open prior to landing the test plug in the wellhead and that the valve remains open and is monitored during all BOP testing.
Function and pressure test the BOP and choke manifold to 250 psi low and 3,500 psi high for 5 minutes each test. Function and pressure test annular preventer to 250 psi low and 2,500 psi high for 5 minutes each as per the BOP test procedures section of this wellplan.
Pull test plug. PU and set bowl protector.
Required reports following running P1 protective casing are:
casing tally,
casing report with a complete description of the casing string,
cementing reports with a complete description of the cement calculations, volumes pumped, cement slurry makeup and interval times during cementing operations.
1. As happened on RB-53 ↑
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Drilling 16” Vertical Hole Section Good Procedure
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