B4 and B6 fields location
Located in the Baltic Sea, the B4 and B6 natural gas fields lie in the eastern part of the Polish exclusive economic zone. The B4 reservoir is situated at a depth of 1,100m below the sea level and is approximately 90km from the coastline. The B6 reservoir lies 1,450m below the sea level and is roughly 75km from the coastline.
Discovery and reserves
The two reservoirs were discovered in 1981-1982 during the exploration operations conducted by the International ‘Petrobaltic’ Joint Organisation for Oil Exploration. The B4 reservoir was discovered by drilling three boreholes, while the B6 reservoir was identified by drilling two boreholes.
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The combined recoverable reserves of the fields are estimated to be 4bcm (149bcf). The recoverable reserves of B4 are estimated to be 1,972.4mcm and that of B6 are estimated to be 1,792.85mcm.
Baltic Gas project development details
The project includes reservoir drilling and borehole production of natural gas, construction of gas pipeline, and transporting the extracted gas first into the production system on the production rig and then to the hydrocarbon conversion system at the Wladyslawowo combined heat and power plant owned by Energobaltic.
The project will be developed in two phases with phase one consisting of the B6 field development. It will include the drilling of up to four production boreholes and setting the foundations for an unmanned production rig. A subsea gas pipeline will also be constructed to connect to the Wladyslawowo plant.
Phase two of the development will feature the B4 field involving the drilling of up to four production boreholes and installing an unmanned rig. An undersea gas pipeline will also be constructed to connect to the main production rig located on the B6 field where the extracted gas will be blended. The second phase is expected to start between 2022 and 2027.
Drilling operations
A total of four boreholes are planned to be drilled in each of the two fields that will include both vertical and horizontal boreholes. The maximum length of the vertical and horizontal sections is expected to be 3,000m for the B4 field and 3,100m for B6 field. The drilling will be performed by the Lotos Petrobaltic jack-up rig owned by Lotos Petrobaltic.
Subsea connection
An 85km-long DN250 subsea pipeline will be laid between the B6 field and the onshore plant, during the first phase of the development. A 33km-long DN150 pipeline will be laid in the second phase, to connect the B4 and B6 fields.
The pipelines will be installed in excavation made at the sea bottom and will be covered with sediments. The thickness of the protective layer will vary from 1m in the high seas to 3m while approaching land.
Contractors involved with the Baltic Gas project
A contract was awarded to Jacobs Engineering Group in February 2016 to conduct a pre-FID study for an onshore gas treatment plant for the project. The scope of work also includes preparing a cost estimate based on vendor quotations for the project to aid in the FID.
Subsea Engineering Associates was contracted in January 2016 for detailed design, procurement and construction management. The scope of work includes subsea pipelines, horizontal directional drilling (HDD) shore crossing, pre-lay and post-lay trenching, risers and platform tie-ins, as well as system engineering including reservoir to gas plant flow assurance.
Part of the Petrofac group, SPD entered a master services agreement in November 2014 to provide front-end engineering design (FEED) for the project.
