Tanzania’s long-dormant Eyasi-Wembere rift basin has returned fresh signs of hydrocarbons, with recent geochemical, seismic, and borehole studies pointing to rocks capable of storing oil.
If confirmed by drilling, the find could shift Tanzania’s energy balance boosting domestic supply and drawing new upstream investment even as the country balances gas-export ambitions and clean-energy pressures.
Why This Matters Now
The Eyasi-Wembere exploration brings onshore Tanzania back into the spotlight at a moment when the government is restarting licensing rounds and negotiating major LNG and gas projects.
Onshore oil discoveries would affect local jobs, fuel import bills, and fiscal revenues and create strategic choices about whether to prioritize domestic refining, export pipelines, or leave resources undeveloped amid climate concerns.
What Investigators Found So Far
Surface Geochemistry and Seismic Lines Point to Hydrocarbon-Bearing Rocks
Tanzania Petroleum Development Corporation (TPDC) and partners have run surface geochemical surveys and satellite seep analysis across the Eyasi-Wembere Block. Final interpretations drawing on Amplified Geochemical Imaging (AGI) and remote sensing done up to 2023 show geochemical anomalies consistent with hydrocarbons and rock units that can act as reservoirs. Those baseline studies preceded more detailed seismic acquisition in 2023 and follow-up 2D seismic in recent months.
Seismic Coverage, Cost, and Field Work
Initial surveys covered roughly 260 kilometers of seismic lines in early phases, and authorities say extra 2D seismic collection is ongoing as part of an extended campaign to map subsurface structures before any drilling decision. Local reporting notes the exploration program has been staged since 2015 and that initial aerial surveys and shallow work cost in the low billions of Tanzanian shillings roughly TZS 8 billion for early fieldwork and TZS 10 billion for the first seismic phase.
Boreholes and Biostratigraphy Strengthen the Case
New academic work a 2025 biostratigraphy and paleoenvironment study used data from three boreholes (Kining’inila-1 at 170 m, Luono-1 at 232 m, and Nyalanja-1 at 302 m) to characterize sedimentary successions and depositional settings in the Eyasi and Wembere sub-basins. That stratigraphic detail helps geoscientists correlate source rocks, maturation levels, and potential reservoir intervals, a necessary step before any commercial drilling.
How the Eyasi-Wembere Story Fits in Tanzania and East Africa
National Upstream Policy and Licensing Context
Tanzania relaunched a formal upstream push in 2025, launching a fifth licensing round that included dozens of blocks offshore and onshore as the country seeks new investment across basins. The Eyasi-Wembere activity runs alongside this national drive to broaden the exploration portfolio beyond the prolific Rovuma gas plays and existing fields. That gives decision-makers options: award acreage to international partners, fund further state-led appraisal, or seek public-private partnerships.
Regional Precedents and Lessons
East Africa’s recent energy history offers both promise and caution. Mozambique and Tanzania’s offshore gas developments show how quickly large gas finds can reshape economies but they also show long lead times, complex fiscal deals, and social impacts.
Uganda’s Lake Albert oil case demonstrates the need for early planning on local content, roads, pipeline routes, and environmental safeguards if onshore discoveries move to development. Eyasi-Wembere sits inside the East African Rift System, geologically comparable to other rift basins that have yielded hydrocarbons but the jury is still out until appraisal wells are drilled.
Who’s Watching and What’s Next
Regulators and national agencies including PURA and TPDC have been monitoring field operations and data acquisition. Authorities say further seismic interpretation, geochemical follow-up, and a decision on exploratory drilling will be guided by the interpreted data and by commercial interest from explorers.
If seismic and geochemistry keep showing promising traps and mature source rocks, the next step would be targeted appraisal wells, an expensive phase that typically requires international partners and robust fiscal terms.
Economic and Social Implications
Short Term
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Jobs during seismic, geochemical, and drilling campaigns (survey crews, technicians, camp services).
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Government spending on infrastructure and local procurement during exploration phases.
Long Term (If Commercial Volumes Are Confirmed)
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Potential to reduce fuel imports and conserve foreign exchange if domestic crude replaces refined product imports.
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Fiscal revenues from royalties and production sharing subject to contract terms.
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Need for planning on pipelines, refining or export routes, and stronger environmental and social governance frameworks.
Risks and Constraints
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Exploration uncertainty: Surface and seismic indicators do not guarantee commercial volumes only drilling can confirm reserves.
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Financing and partners: Drilling and development require large capital and operator expertise; Tanzania will need credible partners under transparent terms.
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Environmental and community impacts: Onshore development raises land use, water, and biodiversity risks that must be managed with strong safeguards and community engagement.
Also read: Top 10 ESG Investment Trends Driving Africa’s Green Economy in 2025
FAQs
1. Has oil been discovered in the Eyasi-Wembere Basin?
No commercial oil has been produced yet. Recent studies and surveys show geochemical and seismic indicators and stratigraphic evidence suggesting hydrocarbon potential, but appraisal drilling is required to confirm commercial discovery.
2. Who is conducting the Eyasi-Wembere exploration?
Work has involved the Tanzania Petroleum Development Corporation (TPDC), national regulators such as PURA, and academic teams for stratigraphy and biostratigraphy; additional contractors handle seismic and geochemical surveys.
3. When will Tanzania drill appraisal wells in Eyasi-Wembere?
No firm drilling schedule is public. Authorities are completing seismic interpretation and data integration; a decision to drill depends on those results and on securing commercial partners and financing.
4. Could Eyasi-Wembere reduce Tanzania’s fuel imports?
If commercial oil volumes are proven and developed, domestic crude could reduce imports and save foreign exchange. That outcome requires successful drilling, development choices (local refining vs. export), and time.
5. How does Eyasi-Wembere compare with Tanzania’s gas projects?
Tanzania’s offshore Rovuma Basin and other gas assets are large, export-oriented projects (including LNG plans). Eyasi-Wembere is an onshore oil prospect; its scale and role would depend on what appraisal wells reveal complementing, not replacing, the country’s gas strategy.
