Beyond legal review and any credential evaluation or translation, budget for documenting multiple work locations, and check separately whether a state licence or registration for geology practice carries its own application costs. Government fees for the immigration route should be confirmed against current published amounts.
Ask who pays for what, in writing
Field assignments often involve employer-paid travel, camp costs and equipment, and those arrangements are usually clear. Immigration preparation costs are less often addressed. Ask the employer before spending whether it covers legal review, document preparation or any licensing application, and get the answer in writing.
Whether costs are reimbursed is a question to put to the employer, not something to assume from practice elsewhere. Hypothetical example: a land surveyor is asked to work across two states, one of which requires registration before any survey may be signed. The registration application, its examination and any reciprocity review carry their own charges and their own timetable, and none of that is an immigration cost.
List every expected outlay in one column and who is expected to pay it in the next: legal review, credential evaluation for a degree awarded outside Canada, Mexico or the United States, certified translations, government charges, and any state licensing step. Send that list to the employer and ask for confirmation in writing rather than a verbal assurance. Where the employer declines an item, it is better to know before the file is assembled.
Confirm government amounts against the published figures at the moment of filing, since quoted numbers age.