As of March 2021, no longer restricted. Previously, foreign investment in offshore drilling, platform construction and geothermal-related services was permitted with majority, but not full foreign ownership.
"APPENDIX III - REGULATION OF THE PRESIDENT OF THE REPUBLIC OF INDONESIA NUMBER 49 OF 2021 CONCERNING AMENDMENT TO PRESIDENTIAL REGULATION NUMBER 10 OF 2021 CONCERNING THE INVESTMENT BUSINESS SECTOR
LIST OF BUSINESS FIELDS WITH CERTAIN REQUIREMENTS
- Oil and gas construction services (Platform), [...] Offshore oil and gas drilling services [see 2019 restrictions below]: Open (without condition) [no longer listed] 
- Geothermal surveying services, Geothermal drilling services [see 2019 restrictions below]: Open (without condition) [no longer listed]
- Geothermal operation and maintenance services [see 2019 restrictions below]: Open (without condition) [no longer listed][...]"(Presidential Regulation (PERPRES) No. 49 of 2021 Concerning Amendments to Presidential Regulation Number 10 of 2021 concerning Investment Business Fields [google translation])
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Previously: up to 2020
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"APPENDIX III - REGULATION OF THE PRESIDENT OF THE REPUBLIC OF INDONESIA NUMBER 44 YEAR 2016 CONCERNING LISTS OF BUSINESS FIELDS THAT ARE CLOSED TO AND BUSINESS FIELDS THAT ARE OPEN WITH CONDITION TO INVESTMENT - 
LIST OF BUSINESS FIELDS THAT ARE OPEN UNDER SPECIFIC CONDITIONS [...]
D. Energy and Mineral Resources Sector
-Oil and gas construction services (Platform): Foreign capital ownership Max.75%
-Geothermal surveying services: Foreign capital ownership: Max.95%
-Offshore oil and gas drilling services : Foreign capital ownership: Max.75%
-Geothermal drilling services: Foreign capital ownership: Max.95%
-Geothermal operation and maintenance services: Max.90% [...]"(PRESIDENTIAL REGULATION OF THE REPUBLIC OF INDONESIA NUMBER 44 YEAR 2016 CONCERNING LISTS OF BUSINESS FIELDS THAT ARE CLOSED TO AND BUSINESS FIELDS THAT ARE OPEN WITH CONDITIONS TO INVESTMENT)
Presidential Regulation (PERPRES) No. 49 of 2021 Concerning Amendments to Presidential Regulation Number 10 of 2021 concerning Investment Business Fields [google translation]
PRESIDENTIAL REGULATION OF THE REPUBLIC OF INDONESIA NUMBER 44 YEAR 2016 CONCERNING LISTS OF BUSINESS FIELDS THAT ARE CLOSED TO AND BUSINESS FIELDS THAT ARE OPEN WITH CONDITIONS TO INVESTMENT
[<a href="https://peraturan.bpk.go.id/Home/Details/168534/perpres-no-49-tahun-2021">PR49</a>],[<a href="https://peraturan.bpk.go.id/Home/Details/161806/perpres-no-10-tahun-2021">PR10</a>],[<a href="https://peraturan.bpk.go.id/Home/Details/40374/perpres-no-44-tahun-2016">PR44</a>]