code:

-- create new resources. skip_x and skip_y are mostly for crude oil (everything else only takes up one tile anyway).
-- res_names: coal, stone, crude-oil, copper

res_name = "crude-oil"; skip_x = 3; skip_y = 4; start_x_offset = 10; start_y_offset = 10; end_x_offset = 10; end_y_offset = 10; 
for pos_x = game.player.character.position.x - start_x_offset, game.player.character.position.x + end_x_offset, skip_x do 
  for pos_y = game.player.character.position.y - start_y_offset, game.player.character.position.y + end_y_offset, skip_y do 
    if (game.canplaceentity{name = res_name, position = {pos_x, pos_y}}) then 
      game.createentity{name = res_name, position = {pos_x, pos_y}, amount = 20000000}; 
    end 
  end 
end 
res_name = nil; skip_x = nil; skip_y = nil; start_x_offset = nil; start_y_offset = nil; end_x_offset = nil; end_y_offset = nil;