Foreign investment in upstream oil exploration and  production activities is prohibited.
"Article 3
The council shall have the authority to issue a list of activities excluded from foreign investment. [...]" (Foreign Investment Law in the Kingdom of Saudi Arabia, 2019) [...]" (Foreign Investment Law in the Kingdom of Saudi Arabia, 2019)
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"Article 2 Without prejudice to the list of activities excluded from foreign investment, to invest foreign capital in any investment activity whether on a permanent or temporary basis, a license shall be issued by the Authority in accordance with the Law, the Regulations, and the decisions issued by the Board. The license approval decision shall be issued under the signature of the Governor or his designee within a period of 30 working days from the date of completing the documents required pursuant to these Regulations and satisfying the conditions and controls for granting the license. 
Article 3 The Council of Ministers shall have the competence to issue a list of the activities excluded from foreign investment. 
Article 4 The foreign investments to be licensed under the provisions of the Law and these Regulations may take either of the following two forms: 1. firms owned by a national and a foreign investor; and 2. firms wholly owned by a foreign investor. The legal form of such firms shall be confined to a limited liability company, a joint stock company, a foreign company branch, or any other legal form with regard to which the Board of Directors shall issue a decision. 
[...]
Article 6 Conditions and Controls for Licensing Foreign Investment: 1. The investment activity to be licensed shall not be included in the list of activities excluded from foreign investment. [...]" (Regulations of the Foreign Investment Law Promulgated by the Board of Directors of the General Investment Authority Decision no. (2/74), dated 12/5/1435H, as Amended )
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"14.01 Appendix (1): List of Businesses Excluded from Foreign Investment
Industrial Sector:
1. Oil exploration, drilling and production. Except the services related to mining sector listed at (CPC 5115+883) in International Industrial classification codes. [...]" (Ministry of Investment, Services Manual [8th edition], Jan 2020)
Foreign Investment Law of Saudi Arabia, 2019
Regulations of the Foreign Investment Law Promulgated by the Board of Directors of the General Investment Authority Decision no. (2/74), dated 12/5/1435H, as Amended 
Ministry of Investment, Services Manual [8th edition], Jan 2020
[<a href="https://www.misa.gov.sa/media/1743/foreign-investment-law.pdf">Law</a>],[<a href="https://misa.gov.sa/media/1300/اللائحة-التنفيذية-لنظام-الاستثمار-الأجنبي-تحديث-9-2020_en-pdf.pdf">Regulatioin</a>],[<a href="https://www.misa.gov.sa/media/1128/moi-service-manual-8th-edition-en-v4.pdf">Manual</a>]