Field Development Plan — Cheyenne

Generated by the worldenergydata field-development playbook (epic #567). Recommendation is heuristic (Concept Select / FEL-1 fidelity), not a sanctioned design.

Engineering rationale

Cheyenne is a stranded deepwater gas accumulation in ~2,748 m of water in Lloyd Ridge 399, far from existing infrastructure, so it was developed as a long-distance subsea tieback to Anadarko's Independence Hub semisubmersible rather than as its own facility (the semisub is the HOST, not the field's concept). Cheyenne's ~72 km tieback was among the longest gas tiebacks in the Gulf, demanding aggressive flow assurance (hydrate and liquids management with methanol/MEG and lean-gas operating philosophy) to keep single-phase-dominated gas moving over that distance. As a dry-gas subsea development, wet trees feeding a shared 1 Bcf/d processing semi was far cheaper than a dedicated host for a depleting gas reservoir. Independence Hub exhausted its anchor fields and ceased production around 2015, with wells permanently abandoned. Notable: Among the longest deepwater gas subsea tiebacks in the Gulf of Mexico (~45 miles to Independence Hub).

Field parameters

Water depth
2748.0 m
Concept
subsea_tieback
Fluid
gas
Operator
Occidental (via Anadarko acquisition, 2019); field/host decommissioned
Wells
4
Plateau
Tieback
72.0 km
First oil
2007

Recommended concept shortlist

ConceptScoreTreesRationale / flags
subsea_tieback ★0.807wettieback not clearly attractive (distance/capacity/size)
subsea_to_shore0.734wet
fpso0.688wethurricane regime: FPSO needs a disconnectable turret
flng0.622wet

★ = the concept actually selected for this field (where known).

Economics & execution (engine estimate)

Dev system
subsea20
Est. CAPEX
498.0 $MM
Est. NPV
Install vessels
8
Max crane
5000.0 t
Hardware
RJ-08-HYD-15K

As built (actuals)

Host
Independence Hub semisubmersible (Mississippi Canyon 920)
Play
Miocene deepwater gas sands
First oil
2007
BSEE code
LL399
Confidence
high

Architecture & layout (subsea_tieback)

Subsea architecture — Cheyenne flowline umbilical jumper control jumper control jumper control jumper control export Export Existing Host (tieback) Manifold 1 XT 1 XT 2 XT 3 XT 4
Subsea architecture block diagram
Field layout — Cheyenne Subsea manifold Manifold 1 Subsea tree (wet XT) XT 1 Subsea tree (wet XT) XT 2 Subsea tree (wet XT) XT 3 Subsea tree (wet XT) XT 4 Existing host (tieback) Existing Host (tieback) Export Export N 1 km
Plan-view field layout (to scale)

Sources: SubseaIQ field catalog (~2014) + BSEE + curated vessel/ subsea catalogs. Schematics are deterministic, generated from the field concept.