ExxonMobil (XOM -2.78%), its partners Hess (HES 0.67%), and China's CNOOC have found a treasure trove of oil in the Stabroek block offshore Guyana. The Exxon-operated venture recently unveiled its latest discovery: Bluefin. It's the first one this year and the 30th since the initial discovery in 2015.

Rival oil giant Chevron (CVX 0.37%) wants a piece of that action. That led it to seal a deal to buy Hess for about $60 billion. However, Exxon doesn't plan to let its rival into this lucrative field without a fight. Here's why these big oil behemoths want Hess' interest in the Stabroek block.

An offshore oil goldmine

ExxonMobil and its partners made their first significant oil discovery offshore Guyana (Liza) in 2015. The companies made a final investment decision to develop that discovery (Liza phase 1) two years later. It started production in 2020, less than five years after its discovery, which is extremely fast for an offshore oil project.

The partners have since made 30 total discoveries, including Bluefin. Those discoveries hold more than 11 billion barrels of oil equivalent resources. The companies have made final investment decisions on several projects. The region currently produces 645,000 barrels per day and should reach over 1.2 million barrels per day by 2027 when its sixth project comes online. Exxon ultimately envisions investing $40 billion across 10 projects to fully develop this resource.

Offshore Guyana is a treasure for Exxon and its partners. The production costs are very low, enabling the companies to earn high profit margins. The production also has a low carbon intensity. These features enable Exxon to achieve its goals of growing its profits while reducing its carbon footprint.

Fighting over the oil field

Hess' 30% interest in the Exxon-operated Stabroek block is the main reason Chevron is trying to acquire the company. The oil giant highlighted, "The acquisition of Hess upgrades and diversifies Chevron's already advantaged portfolio. The Stabroek block in Guyana is an extraordinary asset with industry leading cash margins and low carbon intensity that is expected to deliver production growth into the next decade." The company estimates that the acquisition would enable it to double its free cash flow by 2027 at $70 oil while extending its production and free cash flow growth outlook into the 2030s. Driving that view is the high-margin production the region currently produces and the visible growth on the horizon as Exxon develops additional projects.

The Stabroek block is so valuable to Exxon that it's trying to exert its pre-emptive rights to buy Hess' stake in the field, which it believes Chevron's deal triggered. That would enable Exxon and its other partner to increase their stake in the valuable oil field. Exxon has made it clear that it has no desire to buy Hess; it could have bought the oil company instead of Pioneer Natural Resources. It wants to preserve its right to acquire Hess' interest in the valuable Stabroek block.

The companies are currently in arbitration over the dispute. If Exxon wins, Chevron will likely abandon its deal for Hess. That would diminish its growth profile, given that acquiring Hess was the key to enhancing and extending its growth outlook. Meanwhile, Exxon could then make an offer to acquire Hess' operations in Guyana to enhance its long-term growth outlook. On the other hand, a Chevron victory would enable it to buy Hess and enhance its already strong long-term growth outlook.

An epic battle for a world-class oil field

Guyana is one of the four pillars of Exxon's long-term growth strategy. The region is getting more valuable with each discovery. That's why Exxon is fighting with Chevron for control over Hess's stake in the lucrative oil field. The winner of that epic battle of big oil behemoths will be able to enhance and extend their growth outlook. That makes it a very interesting development for investors to watch.