Existing Rig Feature
Rig Move Capability:
Fast Moving Rig on Rig move dollies
Cluster Well Capability:
Total 24 wells, Eight (8) wells on a row, total three (3) rows, 45 feet distance between the adjacent rows, 20 feet distance in between wells on the row.
Total 140 feet longitudinal and 90 feet transversal. The rig (mast and substructure) and shaker tank can move along the well without moving other structures such as mud tanks, mud pumps, utility tanks and power trailer, are kept stationary.
Clearance underneath the substructure
14 feet height and 17 feet wide passage for Christmas tree. Raised catwalk to protect well heads and Christmas trees along the row.
New Drilling Capabilities need to be achieved
ZADCO requested NDC to have newly designed rig to meet cluster well drilling requirements as ZADCO constructed new artificial islands with advanced drilling requirements.
Rigs need to do the drilling job for complete row without dismantling and rig can move longitudinally and transversally with cables and piping without disconnecting the cables and making extensions for pipelines to save rig move time as wells spacing 6m only and one row include 13 wells.
To achieve new drilling requirements, we had to keep power module and mud module in the first location as installed for the first well and move only by rig module and shale shaker.
Rig Move Procedures before Upgrade
In normal rig move procedures for fast moving rigs, due to long distance between old and new locations rig move operation sometimes involved disassembling and reassembling the drilling rig at new location. This operation includes disconnect and reconnect electrical cables and piping.
After arriving the new location, the rig crew has to position and adjust levels of the rig components to achieve the rig layout as per rig layout drawings. Maneuvering of the huge loads on desert to achieve the accurate positioning is hard task and it depends on personal skills and experience. If any relative distance between the components is not matching the approved rig lay out drawings, the drilling crew will face challenge to disconnect then reposition then reconnect electrical cables and piping.
Artificial Islands and Cluster Wells Drilling Techniques
The above scenario of rig move used to be carried out when rig is moving from single well to new distantly separated single well location. Developments in drilling methods and new technology are leading to efficiency improvements for oil and natural gas producers. Artificial islands and “Pad” drilling techniques allow rig operators to drill group of wells more efficiently and allow for extended reach drilling (ERD).
Changing the drilling operation from on the sea (jack up rigs) to on the land drilling operation; lead to prevent the hazards related to sea environmental circumstances. Onshore operation is easier to establish safety surrounding and logistics sustaining qualification in both of drilling and oil extraction operations. The gathering pipeline on artificial islands can be easily combined with main pipeline on land.
Artificial islands may have more than one drilling pad. And each drilling pad may have more than one row of wells spaced fairly close together at the surface; ZADCO UZ-750 project is an example, is for ZADCO south artificial island.