# Halfdan field

Halfdan is a significant oil and gas field in the south-western part of the Danish sector of the southern North Sea. The field has been in production since 1999. The Sif and Igor fields are satellites to Hallfdan.

## The field

The Halfdan field comprises the contiguous Halfdan, Sif and Igor fields in Blocks 5505/13 and 5505/16 of the North Sea. The Sif and Igor fields are respectively to the north and east of the Halfdan field, but are exploited through the Halfdan offshore infrastructure. The south west of the field contains oil of the Maastrichian layers and the north and east area has gas of the Danian era. Key parameters of the fields are given in the table.
Halfdan, Sif and Igor reservoir :
| Parameter | Value |
| Reservoir rock | Chalk |
| Geological age | Danian and Upper Cretaceous |
| Depth, ft | 2030-2100 |
| Discovery | 1998 |
| Field delineation, Halfdan | 100 km$^2$ |
| Field delineation, Sif | 40 km$^2$ |
| Field delineation, Igor | 109 km$^2$ |
| Oil density | 33° API |
| Oil reserves | 35.9 million m$^3$ |
| Gas reserves | 6.9 billion Nm$^3$ |

## Owners and operators

The Halfdan field is currently owned jointly by TotalEnergies, Nordsofonden, and BlueNord. It was formerly operated by Maersk and is currently operated by Total E&P Denmark.

## Production infrastructure

The Halfdan, Sif and Igor fields are exploited by three offshore installations Halfdan A, Halfdan B and Halfdan C, which were installed and came into operation sequentially. The A and B installations are manned multi-platform bridge-linked facilities. And Halfdan C is an unmanned satellite of the B complex. Key parameters of the installations and platforms are given in the table.
Halfdan Installations :
| | Halfdan A | Halfdan A | Halfdan A | Halfdan B | Halfdan B | Halfdan B | Halfdan B | Halfdan C |
| Block | 5505/13 | 5505/13 | 5505/13 | 5505/13 | 5505/13 | 5505/13 | 5505/13 | 5505/13 |
| Name | HDA | HDB | HDC | HBA | HBB | HBC | HBD | HCA |
| Coordinates | 55.230115N 5.005754E | | | 55.537992N 5.030886E | | | | 55.557225N 5.134502E |
| Water depth, m | 43 | 43 | 43 | 43 | 43 | 43 | 43 | 45 |
| Commissioned | 2000 | 2003 | 2003 | 2002 | 2008 | 2007 | 2011 | 2008 |
| Type | Fixed steel | Fixed steel | Fixed steel | Fixed steel | Fixed steel | Fixed steel | Fixed steel | Fixed steel |
| Function | Wellhead, processing | Accommodation 32 beds | Flare | Wellhead, separation | Riser, wellhead | Accommodation 80 beds | Processing | Wellhead, separation |
| Wells | 35 | 35 | 35 | 37 | 37 | 37 | 37 | 9 |
| Bridges | 2: each about 100 metre | 2: each about 100 metre | 2: each about 100 metre | 3: 100 to 140 metre | 3: 100 to 140 metre | 3: 100 to 140 metre | 3: 100 to 140 metre | 0 |
| Substructure weight, t | 2800 | 1000 | 1150 | 3050 | 1800 | 2000 | 3500 | 1100 |
| Topside weight, t | 800 | 2200 | 500 | 2500 | 1380 | 3000 | 9300 | 630 |
| Wells | 35 | 35 | 35 | 37 | 37 | 37 | 37 | 9 |

### Pipelines

In addition to the offshore installations there are a number of pipelines connecting and transferring fluids within the Halfdan field and to adjacent fields which act as oil and gas export routes.
Halfdan and connected pipelines :
| From | To | Fluid | Length, km | Diameter, inches | Note |
| HDA | HBA | Gas, oil, water | 1.7 | 12 | |
| HBA | HDA | Gas, oil, water | 1.7 | 14 | |
| HBA | Dan | Gas, oil, water | 11 | 20 | |
| Dan | HDA | Injection water | 9 | 14 | |
| HDC | HBA | Gas | 2 | 24 | |
| HCA | HBB | Gas | 7 | 16 | |
| HCA | HBB | Oil | 7 | 8 | |
| HDA | Dan | HP Gas | 9 | 12 | |
| HDA | Dan | LP Gas | 9 | 12 | |
| HDA | Gorm | Oil & condensate | 19 | 14 | Oil export route to shore |
| HBA | Tyra West | Gas | 27 | 24 | Gas export route to shore |
Halfdan A and B have their own power supplies but are also interconnected. Halfdan C receives power from Halfdan B complex.

## Oil and gas production

Oil and gas from the reservoir are produced via a number of wells. In addition water injection is used to sweep oil towards the oil production wells.

### Wells

* Oil production wells: 38 (Halfdan)
* Gas production wells: 16 (Sif and Igor)
* Water injection wells: 27 (Halfdan)

### Plant capacity

* The capacity of the plant on Halfdan A is: Oil 120,000 BOPD; Gas 120 MMSCFD; Produced water 115,000 BWPD.
* The capacity of the plant on Halfdan B is: Oil 90,000 BOPD; Gas 125 MMSCFD; Produced water 180,000 BWPD.

### Annual production and injection

Halfdan annual oil, gas and water production and water injection 1999-2013 :
| Year | 1999 | 2000 | 2001 | 2002 | 2003 | 2004 | 2005 | 2006 | 2007 | 2008 | 2009 | 2010 | 2011 | 2012 | 2013 |
| Oil production, 1000 m$^3$ | 222 | 1120 | 2365 | 3718 | 4352 | 4346 | 6000 | 6085 | 5785 | 5326 | 5465 | 5119 | 4905 | 4617 | 4150 |
| Gas production, million normal m$^3$ | 37 | 178 | 522 | 759 | 1142 | 1449 | 2582 | 2948 | 2675 | 3104 | 3401 | 2885 | 2343 | 1709 | 1389 |
| Produced water, 1000 m$^3$ | 56 | 237 | 493 | 367 | 612 | 2099 | 2825 | 3460 | 4086 | 4766 | 4814 | 5519 | 6149 | 6139 | 6099 |
| Water injection, 1000 m$^3$ | 62 | 13 | 649 | 2532 | 5162 | 5759 | 9710 | 11026 | 12107 | 12727 | 11485 | 11945 | 12277 | 10912 | 10921 |
Halfdan annual oil, gas and water production and water injection 2014-22 :
| Year | 2014 | 2015 | 2016 | 2017 | 2018 | 2019 | 2020 | 2021 | 2022 |
| Oil production, 1000 m$^3$ | 3674 | 3345 | 2780 | 2700 | 2385 | 2084 | 1733 | 1498 | 1433 |
| Gas production, million normal m$^3$ | 1309 | 1334 | 1191 | 1209 | 1203 | 1008 | 924 | 844 | 808 |
| Produced water, 1000 m$^3$ | 6574 | 7344 | 6709 | 7315 | 7190 | 7421 | 6879 | 6858 | 7452 |
| Water injection, 1000 m$^3$ | 11403 | 10760 | 8555 | 10032 | 8316 | 8823 | 8957 | 8716 | 8513 |

## Future plans

Plans for future development of the field include: the Halfdan Ekofisk infills; HCA gas lift; Halfdan Tor NE infill; and Halfdan Northeast project.
It has been estimated that the field will remain economically viable until 2035.