This article describes the sequence of operations and the general practices for a typical onshore well.
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Operations |
General Practices |
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1. Prepare access road and well lease |
Minimise environmental impact due to survey/construction - Prepare environmental report and map - Obtain final survey of Lat./Long/Evaluation - Avoid natural drainage routes, significant topographical disruption. Early contractor site inspection Arrange timely water supply (well/logistics) |
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2. Construct cellar and install conductor |
Cellar dimensions are rig-specific Stove Pipe depth; minimum 6ft. Drilling Contractor will install stove pipe. Ensure conductor is vertical, stove pipe flange is level; |
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3. Pre-spud meeting, rig mobilisation and spud well |
Pre-spud topics: target zones, geology, drilling, electric logging, DST’s (field safety/pre-spud meeting also held) Follow Drilling Contractor rig move procedures Communications between vehicles and sites required at all times Rig-down and rig-up camp the same day if possible Sheaves and travelling block to be inspected during move Rathole/mousehole to be drilled while WOC (conductor) |
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4. Drill 26in Surface Hole |
Drill 26in hole to depth specified in Drilling Programme Drill using water with viscous pills If circulation is lost drill blind Ensure hole is cleaned regularly Take TOTCO surveys every 100 feet Place Hi-Vis pill on bottom prior to running casing |
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5. Run and Cement 20in conductor |
Measure, drift and number casing. Clean/inspect threads Threadlock guide shoe and float collar Make up shoe track, check float equipment with water Run centralisers as per Drilling Programme Cement casing and bump plug. Pressure test casing against plug Prepare to perform top up job with stinger if no cement returns WOC minimum 4 hours |
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6. Drill 17.1/2 in Hole |
Clean out 20in conductor and drill out shoe with slick Drill 17.1/2in hole to depth specified in Drilling Programme Drill using spud mud with viscous pills If circulation is lost drill blind and pump 30 bbl Hi-Vis pills every third connection or as required Ensure hole is cleaned regularly Single shot surveys to be taken every 300 feet |
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7. Run and Cement 13.3/8in Conductor |
Measure, drift and number casing. Clean/inspect threads Threadlock guide shoe and float collar (bottom 80ft) Make up shoe track, check float equipment with water Run centrilizers as per Drilling Programme Cement casing while reciprocating and bump plug. Pressure test casing against plug If no cement returns, top up 20in x 13.3/8in annulus WOC minimum 8 hours. Install 13.3/8in x 13.5/8in casing head housing N/U BOP’s and test rams to 5 000 psi, hydril to 1 500 psi Install wear bushing |
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8. Drill 12.1/4 in hole interval |
Drill out 13.3/8in shoe track and displace to water based mud Drill 10ft of new formation and perform a leak-off test Drill 12.1/4in hole to depth specified in Drilling Programme Conduct drill-off tests for optimum WOB Surveys required as per Drilling Programme Wiper trip at TD, spot a 150 bbl Hi-Vis pill (70 FV) Retrieve wear bushing |
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9. Run and cement 9.5/8in casing |
Measure, drift and number casing, clean/inspect threads Threadlock guide shoe and float collar (bottom 80ft) Make up shoe track, check float equipment with water Centralizers as per Drilling Programme Use both top and bottom combination wiper plugs Bump plug, hold 500 psi above displace pressure 15 minutes WOC minimum 4 hours before slacking off casing or until surface sample is hard Collect water sample for testing production casing cement Remove BOP stack Install 13.5/8in x 10.3/4 in casing slips, cut/dress casing stub Install 13.5/8in casing spool and test seals to 2 400 psi |
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10. Nipple-up and test BOP stack
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Pressure test BOP equipment to Company standards Rams to 5 000 psi and Hydril to 3500 psi. HP tests to 2 000 psi for 15 minutes; LP tests to 500 psi for 15 minutes or as detailed in Programme Install wear bushing |
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11. 8.1/2in hole section |
Drill out 9.5/8in shoe track with well water Circulate well to non-damaging mud Drill 10ft of new formation and perform formation integrity test Drill 8.1/2in hole to TD as specified in Drilling Programme Survey requirement as per Programme Conduct drill-off tests on each bit for optimum WOB Raise MW as required |
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12. Log 8.1/2in hole section |
Run open hole logs specified in Drilling Programme Borehole must be smooth, clean and conditioned for logging Confirm availability of fishing equipment for all logging tools Loggers to safely secure/locate explosives/radioactive sources Wiper trip to TD, circulate condition mud Retrieve wear bushing |
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13. Perform Drill Stem Test subject to log results, according to Testing Programme |
Circulate/condition the hole prior to running openhole DST Measure and record all tools, prepare/issue running list Include a pup joint for correlation; run log before setting packers - if required Rig up, make secure and pressure test all test lines Fill annulus prior to opening test tool, thereafter monitor level Drilling Supervisor to be present during all setting/opening/recovery and unseating/POOH of DST tools; tests will not start in darkness Well is to be monitored for swabbing; continuous fill-up is NOT permissible while POOH Follow reverse-out procedures to ensure optimum recovery |
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14. Run and cement production casing or liner, subject to log results and testing |
Run 5.1/2in/7in/7.5/8in casing or liner Measure, drift and number casing, clean/inspect threads Conditioning trip, spot a 40 bbl Hi-Vis pill (70 FV) Change bottom rams to casing rams and pressure test Threadlock float shoe and float collar Make up shoe track, check float equipment with water Centralisers as per Drilling Programme Pup joint will be located above each pay zone if available Mud left in annulus after cementing will be treated with Biocide Pre-flush brine will be equivalent density to mud; treat with SAPP and Biocide Calculate cementing volumes using caliper values; use top and bottom cement plugs TOC to be 200 ft above highest hydrocarbon-bearing zone (minimum) Displace with cement unit, using water (containing corrosion inhibitor if specified). Reciprocate casing until plug bumps Hold pressure at 500 psi above displacement pressure for 15 minutes Confirm actual TOC with displacement pressure off Drill out cement to shoetrack Run bit and scraper to TD inside casing Log CBL/USIT/GR for zonal isolation Circulate well to clean filtered brine Pressure test casing to 3 500 psi |
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15. Completion and Clean Up |
Run completion as per Programme Perforate well according to log analysis Clean up well until BS&W<1% Flow well |
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16. Suspend or abandon the well depending on results of logs and well tests |
Suspend for completion by Production Department, or/ Submit notice of Intention to Abandon including proposed plug intervals to operations Isolate all permeable zones with 200 ft of cement above/below each zone. Casing; 70 ft above/100 ft below shoe Ensure isolation between producing formations |
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17. Survey the well location |
Well location and elevation to be surveyed not later than 6 months after well spud date |
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18. Restore the well location |
Site will be restored to original condition; access roads left in useable/acceptable condition |