{
  "oil_region_system": {
    "resource_type": "crude_oil",
    "description": "Oil feature selection based on region mass and biome compatibility",

    "features": {
      "major_oil_field": {
        "display_name": "Major Oil Field",
        "incompatible_biomes": ["alpine", "rocky_plateau", "wetlands"],
        "frequent_biomes": ["grassland", "scrubland", "hot_desert"],
        "minimum_region_mass": 250,
        "quality_base": "premium",
        "extraction_difficulty": "hard",
        "budget_impact": 5,
        "description": "Large oil reservoirs requiring massive sedimentary basins"
      },

      "oil_well": {
        "display_name": "Oil Well",
        "incompatible_biomes": ["alpine", "wetlands"],
        "frequent_biomes": ["grassland", "temperate_forest", "scrubland"],
        "minimum_region_mass": 75,
        "quality_base": "standard",
        "extraction_difficulty": "medium",
        "budget_impact": 4,
        "description": "Standard oil deposits in medium regions"
      },

      "shallow_oil_pocket": {
        "display_name": "Shallow Oil Pocket",
        "incompatible_biomes": ["alpine", "wetlands"],
        "frequent_biomes": ["grassland", "temperate_forest", "scrubland", "hills"],
        "minimum_region_mass": 30,
        "quality_base": "standard",
        "extraction_difficulty": "easy",
        "budget_impact": 3,
        "description": "Surface-near oil accessible in small regions"
      },

      "oil_seep": {
        "display_name": "Oil Seep",
        "incompatible_biomes": ["alpine", "cold_desert", "wetlands"],
        "frequent_biomes": ["grassland", "scrubland", "temperate_forest"],
        "minimum_region_mass": 15,
        "quality_base": "medium",
        "extraction_difficulty": "very_easy",
        "budget_impact": 2,
        "description": "Natural oil emergence in tiny regions"
      },

      "offshore_oil": {
        "display_name": "Offshore Oil",
        "incompatible_biomes": ["hills", "rocky_plateau", "alpine", "hot_desert"],
        "frequent_biomes": ["coastal_plain"],
        "minimum_region_mass": 150,
        "quality_base": "premium",
        "extraction_difficulty": "very_hard",
        "budget_impact": 4,
        "description": "Marine oil deposits in coastal regions"
      },

      "tar_sands": {
        "display_name": "Tar Sands",
        "incompatible_biomes": ["alpine", "hot_desert", "wetlands"],
        "frequent_biomes": ["grassland", "temperate_forest"],
        "minimum_region_mass": 200,
        "quality_base": "low",
        "extraction_difficulty": "very_hard",
        "budget_impact": 3,
        "description": "Heavy oil requiring large sedimentary systems"
      },

      "shale_oil": {
        "display_name": "Shale Oil",
        "incompatible_biomes": ["alpine", "wetlands", "tropical_rainforest"],
        "frequent_biomes": ["grassland", "scrubland"],
        "minimum_region_mass": 100,
        "quality_base": "medium",
        "extraction_difficulty": "very_hard",
        "budget_impact": 3,
        "description": "Unconventional oil in shale formations"
      }
    },

    "selection_logic": {
      "step_1": "Check region mass against minimum_region_mass",
      "step_2": "Filter out features with incompatible biomes",
      "step_3": "Prioritize features with frequent biomes for this location",
      "step_4": "Select from available features",
      "fallback": "If no features available, place generic oil_seep"
    },

    "mass_categories": {
      "tiny_region": {"mass_range": [15, 30], "typical_features": ["oil_seep"]},
      "small_region": {"mass_range": [30, 75], "typical_features": ["shallow_oil_pocket", "oil_seep"]},
      "medium_region": {"mass_range": [75, 150], "typical_features": ["oil_well", "shale_oil"]},
      "large_region": {"mass_range": [150, 300], "typical_features": ["major_oil_field", "offshore_oil", "tar_sands"]},
      "huge_region": {"mass_range": [300, 1000], "typical_features": ["major_oil_field", "tar_sands"]}
    }
  }
}