Enhanced Oil Recovery

Enhanced Oil Recovery Techniques


Enhanced Oil Recovery Methods

This article discusses three distinct techniques utilized in enhanced oil recovery (EOR), an emerging trend in oil and gas exploration and drilling.

EOR Technique: Gas Injection

Gas injection is the most prevalent and rapidly growing EOR method, accounting for 50% of EOR production in the United States. It has consistently demonstrated success in boosting oil production across various types of oil reservoirs. Major oil companies have been employing gas injection since its initial application in Surry County, Texas, during the 1970s.

The primary objectives of gas injection are to restore reservoir pressure, enhance oil production, and reduce operating costs. However, the significant upfront investment required for the necessary equipment and gas components has limited its broader adoption. Despite the potential for lower operating costs, the high initial capital investment has been a barrier for many smaller independent oil companies. Nonetheless, the rise in oil prices has made it feasible for these companies to participate in gas injection EOR.

Gas injection involves the introduction of carbon dioxide, nitrogen, or natural gas into a reservoir. Once injected, the gas expands and forces additional oil into a production wellbore for extraction. The gas subsequently dissolves into the oil, reducing its viscosity and improving its flow rate. In many cases, up to two-thirds of the injected carbon dioxide returns with the produced oil. Re-injecting the recycled carbon dioxide can further reduce operating costs.

Communities like Midwest, Wyoming, have experienced additional benefits from gas injection EOR performed by companies such as Anadarko Petroleum. This technique has cleared the landscape of unsightly power poles, conventional pumping wells, and power lines, while also preventing tons of greenhouse gases from polluting the atmosphere. As Anadarko spokesman Rick Robitaille told the Casper Star-Tribune, "It's good for the economy. It's good for the country. It's good for the environment. It's a very positive scenario."

EOR Technique: Thermal Recovery

Thermal recovery accounts for the other half of EOR production in the United States and is primarily used in California's oil fields. This technique employs heat to improve oil flow rates. Steam is injected into the reservoir to reduce the viscosity of heavy, viscous oil, making it easier to flow and extract. Dolberry Oil estimates that steam constitutes 52% of the EOR market methods, compared to 31% for carbon dioxide and 17% for nitrogen.

Gary Dolberry and Dolberry Oil and Gas possess a proprietary steam injection thermal recovery technology, known as "steam slugging," which most oil production management companies lack. This technology combines carbon dioxide and steam, resulting in roughly twice the hydrocarbon recovery efficiency in two-thirds of the time. Steam slugging typically achieves an additional ten barrels per day and offers benefits such as wellbore cleaning and water disposal.

A commonly used strategy by companies with access to steam slugging is the "Huff and Puff" scenario. In this approach, each well undergoes an 8-12 hour injection period (the "Huff"), followed by a 12-15 hour "Soak" period where carbon dioxide mixes with the crude oil while nitrogen pulls the oil to the lowest pressure area. Steam then provides additional pressure, enhancing oil production by loosening the crude oil in the "pay zone" surrounding the well. Finally, during the "Puff" cycle, the wellbore and surrounding pay zone fill with fluid to be produced or recovered.

EOR Technique: Chemical Recovery

Chemical injection is another technique used in less than one percent of all EOR efforts. This method involves using long-chained molecules called polymers to increase the effectiveness of water floods. Water flooding is a widely used secondary EOR technique that aims to boost overall field output while achieving higher oil-to-water ratios.


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