Investors in Oil & Gas activities are required to source goods and services from Tanzanian-owned firms.
"Sub-Part II - Petroleum Rights, Licences and Agreement
(b) Petroleum Rights and Conditions [...]
Exclusive rights conferred to the National Oil Company
44.-(1) The petroleum operations rights shall be granted to the National Oil Company
(2) The National Oil Company shall have exclusive right over all petroleum rights granted under this Part. [...]
(4) The National Oil Company may, subject to the Minister's consent and on advice by PURA, enter into partnership with a Tanzanian or a foreign entity through an open tendering process or a direct award of a block.
(5) The licence granted under subsection (1) shall require the National Oil Company to maintain a participating interest of not less than twenty five per cent unless the National Oil Company decides otherwise.
(6) A company wishing to carry out petroleum operations in Tanzania outside the scope of a reconnaissance permit shall do so together with the National Oil Company. 
Persons who may partner with the National Oil Company
45. A person is qualified to enter into partnership with the National Oil Company if-
(a) is a body corporate registered under the Companies Act or any other written law; and
(b) such entity is of recognized capacity, technical knowledge and financial capability.
[...]
Sub-Part IV - Licensing of Midstream and Downstream activities
(a) General requirement for undertaking Mid and downstream activities [...]
Consideration of the application 
132. In considering an application for a licence, EWURA shall take into account: [...]
(j) participation of Tanzanians including local companies with not less than twenty five percent participating shares in the business as the case may be in the regulated activities;
[...]
PART VIII - GOVERNMENT PARTICIPATION, LOCAL CONTENT, CORPORATE SOCIAL RESPONSIBILITY AND INTEGRITY PLEDGE
Government participation in petroleum and gas activities
218.-(1) The Government may, through National Oil Company participate in petroleum operations under this Act through a specified participating interest of a licence or contract granted under this Act and in a joint venture established by a joint operating agreement.
[...]
Provision of goods and services by Tanzanian entrepreneurs 
219.-(1) A licence holder, contractors and subcontractors shall give preference to goods which are produced or available in Tanzania and services which are rendered by Tanzanian citizens or Local Companies.
(2) Where goods and services required by the contactor, subcontractor or licence holder are not available in Tanzania, such goods and services shall be provided by a company which has entered into a joint venture with a local company.
(3) The local company referred to in subsection (2) shall own share of at least twenty five percent in the joint venture or as otherwise provided for in the regulations. 
(4) For purposes of subsections (1) and (2), a licence holder, contractor and subcontractor shall prepare and submit to PURA a procurement plan for a duration of at least five years indicating among others, use of local services in insurance, financial, legal, accounts and health matters and goods produced in Tanzania. [...]
(9) For the purpose of this section "local company" means a company or subsidiary company incorporated under the Companies Act, which is one hundred percent owned by a Tanzanian citizen or a company that is in a joint venture partnership with a Tanzanian citizen or citizens whose participating share is not less than fifteen percent." (THE PETROLEUM ACT, 2015)
THE PETROLEUM ACT, 2015
[<a href="https://www.tanzania.go.tz/egov_uploads/documents/THE_PETROLEUM_ACT_2015_No_sw.pdf">Act</a>]