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The more I read and think about energy and geoscience, the more I appreciate how much work remains to be done and how many exciting developments are made each week. Let’s dig into a few …

Rasoul Sorkhabi

Editor, Core Elements

New Life for Depleted Gas Reservoirs, Pt 2.

N.Minton, Shutterstock

There are more than 2 million abandoned oil and gas wells in the U.S. alone, and finding ways to repurpose and commercialize them is a big and important effort.

Catch up fast: In part 1, we explored if these wells could be used for hydrogen storage. This week, we will discuss a recent article in Oil & Gas Journal, which proposes geothermal power generation as an option.

Why it matters:

• Geothermal power from repurposed oil and gas wells produces renewable, clean energy economically.

• Repurposing these wells saves millions on drilling costs for new wells and tens of thousands compared to plugging and abandonment costs for decommissioned wells.

Key variables: Abandoned wells may degrade over time and release methane. To repurpose these wells, it is important to investigate various factors affecting enthalpy and production rates.

Researchers looked at these variables in two case studies:

North Sea simulation:

• A group of researchers from Texas A&M University studied typical North Sea wells to model heat production in a converted decommissioned well.
• It found that reservoir temperature, thickness, and permeability have the most influence on the heat production.

Sarawak case study:

• A study of wells from the Baram basin onshore Sarawak, Malaysia, indicates that a well in the Asam Paya Field with lower geothermal gradient would not be a good candidate for geothermal power.
• The Engkabang West well with a higher geothermal gradient—bottom hole temperature of 243°C and a depth of 6000 m—would result in a 60 Mw power plant.

What will be needed: Based on these two case studies, it seems that heat, permeability, and reservoir thickness are key parameters for successful geothermal power plants in the depleted reservoirs.

Go deeper: Read the full article here.

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New Discovery of Natural Hydrogen in Albania

The saying goes “You won’t find what you don’t look for.” Locating geologic hydrogen used to be rare, but naturally occurring reservoirs are increasingly reported, including one recently discovered in Albania.

Context: Geologic hydrogen was once thought to be a rarity because hydrogen–the lightest and most reactive element–does not hugely accumulate in rock reservoirs.

An explosive discovery: In 1992, a flammable gas was reported at a depth of 620 m in the Bulqizé mine. This was followed by explosions in the mine in 2011, 2017, and 2023. These incidents revealed that hydrogen gas was present.

Location, location, location:

• The new natural hydrogen discovery is in the Bulqizé chromite mine in Albania, one of the largest of its kind. The mine is located within a Jurassic-age ultramafic massif.

• The Bulqizé ultramafic massif is part of the East Mediterranean subduction-zone ophiolite belt that extends for more than 3000 km from Turkey to Slovenia.

Where did it come from? One major question around vast quantities of accumulated natural hydrogen underground is how they got there.

• The authors of this paper suggest the presence of a highly faulted reservoir rooted in the Jurassic ophiolite massif. This scenario should be tested for other such hydrogen accumulations.

Why it matters: If scientists can successfully extract the hydrogen, discoveries in this part of Europe could help meet energy demands in a region historically reliant on Russian oil and gas.

Go deeper: The joint study by a group of French and Albanian researchers is available here.

How Companies are Leveraging the Power of the Permian

When ExxonMobil bought Pioneer Natural Resources last year, it elevated interest and opportunities in the Permian—already the king of U.S. shale production—to an even higher level.

On the rocks: A recent report in The American Oil and Gas Reporter analyzes how O&G companies are leveraging the region’s complex geology.

Leading location: The Permian-age Wolfcamp and Bone Spring remain the main producing formations. Completion design on these primary targets involves 2000-2200 pounds of proppant, plus 47-50 barrels of fluid per lateral length with 10-12 clusters (perforations) for each frac stage.

Barnett boost: Companies are now looking at deeper formations, most notably the Mississippian-age Barnett and Devonian-age Woodford. Unlike the gas-rich Fort Worth basins, the Barnett is oilier, but production from these deeper formations may be costlier.   

Tech approach: Some companies with strong technical skillsets believe it’s more advantageous to work as nonoperating partners in the region. Among these are Henry Resources, a Texas-based company which pioneered Wolfcamp formation development in 2003, and Minnesota-based Northern Oil & Gas Company.

Why it matters: It is important to see how “operators keep [their] eyes open for emerging opportunities,” in this impactful area.

Go deeper: Read the full article here.

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