Drilling Engineering department looking for an effective solution to resume Onshore ERD project, challenging environment and well profile ( one of the deepest and complicated wells in Latin America). Based on the Worldwide nose plot, this well classification will be in the top 100 ERD wells. The client requested a non-standard casing whipstock ( 8 5/8″) making even more difficult the potential chances to finish this project.
Job Profile
Partial mud losses observed while drilling at 5905m MD. LWT was Run in Hole in order to help geologists to confirm casing point and correlate log response vs formation samples, however, geologist did not have solid arguments to confirm casing point and decided to resume drilling operations, so directional BHA RIH and carry on drilling until 6063m MD where total losses appeared.
At this particular time, geologists decided to sop drilling to run 8 5/8″ casing. Casing running operation was successfully accomplished, however cementing operations were complicated because of high ECD ( Slurry density and Casing clearance ). Cementing was not as good as expected because of total losses and high ECD while cementing 8 5/8″ casing.
After cementing ops, 7 5/8″ BHA run in hole to tag cement, total losses were found again and gas influx too. The situation turned almost impossible to carry on with the next drilling stage because of high density required to control gas, but lower density to drill across the reservoir, balance cannot be achieved by having both situations.
The remedial cementing operation was planned. Squeeze volume cement and estimated job time calculations were done and slick BHA was run in hole. After cement displacement was done, BHA was POOH but get stuck around 5500m MD because of cement. Several attempts to release drill pipe were done ( jarring, taper taps, spears) unsuccessfully all of them.
Attempts to reopen the well included two failed maneuvers with Back-off Spear + DP5″LH and a Taper Tap LH, which left the pipe stuck again.
Solution
PathBreaker™ Hydraulic Whipstock aiming to be the solution to solve this problem. After performed positive and negative casing tests to confirm gas coming from the bottom and not from the casing shoe, Hydraulic PathBreaker™ Whipstock was set at 4849m MD based on recovered Drill Pipe and geologist information. Whipstock job successfully executed opening the window in 8 5/8″ in the horizontal section ( 89.5 deg).
The hydraulic anchor system had no issue being set in this difficult well and successfully completed the window milling at the desired depth. A positive and negative pressure test was performed to confirm the theory that gas entered through the shoe. A deviating bucket with a hydraulic anchor (PathBreaker™) was lowered to 4849mMD and a window was opened, thus closing the old stage.
PathBreaker™ Hydraulic System efficiency proved to complete casing milling operation in 5hrs. This can only be achieved thanks to the years of continuous development. Reliable anchor system with multi- expandable profile design was the key to successfully accomplished this operation, helping our customers to carry on with drilling operations and avoid well abandonment.
PathBeaker™ Hydraulic Whipstock was oriented using the Schlumberger MWD system.
Key Notes
- The stage since its inception took approximately 473 days to complete.
- The Stockholm Precision Tools (SPT) PathBreaker™ whipstock intervention took 24 hours to complete
- Drilling 9 5/8″ from 4404mMD to 6063mMD was done with oil-based mud with density 1.53-1.55g / cm3 and it was later extended to 10 1/8″.
- The first severe circulation losses occurred at 5905mMD and subsequently at 5955mMD and 6063mMD.
- The first LWT logging at 5918mMD, did not identify the entrance to the reservoir.
- The cementation of the first section from 6020mMD – 3621mMD was done with total losses, so it was not cemented.
- The first change of oil base mud per water base is made from 1.05 g / cm3 to 3620 mMD before drilling the Tie Back seal.
- The top of the reservoir according to correlation between geophysical records was found at 5860mMD and not at 6040m as the project initially said.
- The TLC record shows the poor cementing of the liner 8 5/8″.
- The pumped cement plug for remediation left the pipe clamped at 5571mMD.
- Operations pending left-hand pipe were stopped on June 7 and resumed after 206 days on December 30, 2018.
Conclusion
SPT and Schlumberger were able to successfully complete this difficult job where others had failed. They saved the client millions of dollars by reopening the well for operation. The PathBreaker™ high-performance tungsten carbide triple mill system allowed for unparalleled speed in sidetracking this well. The client has been able to reopen operation and continue drilling from their previous 8-month hiatus.
