A bill entitled "The Combined Hydrocarbon Leasing Act of 1981".

Amends the Mineral Land Leasing Act of 1920 and the Mineral Leasing Act for Acquired Lands to expand the application of such Acts to include gilsonite and all vein-type solid hydrocarbons.

Provides that acreage in special tar sand areas shall not be chargeable against State acreage limitations applicable to oil and gas lease holders. Defines a special tar sand area as an area designated by the Secretary of the Interior as containing substantial deposits of tar sand.

Provides that oil and gas lands within a special tar sand area shall be leased by competitive bidding in units of not more than 5,120 acres. Provides that competitive leases in special tar sand areas shall be for a primary term of ten years.

Directs the Secretary to review, prior to the commencement of commercial operations, the royalty rates established in each combined hydrocarbon lease issued in special tar sand areas.

Permits the owner of: (1) an oil and gas lease issued prior to the enactment of the Combined Hydrocarbon Leasing Act of 1981; or (2) a valid claim to any hydrocarbon resources leasable under the Act based on a mineral location made prior to January 21, 1926, and located within a special tar sand area to convert such lease or claim to a combined hydrocarbon lease for a primary term of ten years.

Provides that nothing in this Act shall: (1) affect the existing tax status applicable to production from tar sand; or (2) apply to national parks, national monuments, or other lands where mineral leasing is prohibited. Directs the Secretary of the Interior to apply this Act to any unit of the national park system where mineral leasing is permitted, unless there is a finding that there will be significant adverse impacts on such unit or on other contiguous units.