The increasing demand for energy has increased the need for production of hydrocarbon. As a result, operators have exploited more difficult reservoirs (e.g., deeper wells, remote areas, mature depleted fields, and heavy oil reservoirs). Traditional methods are not sufficient for producing heavy oil; therefore, over time, enhanced recovery methods have been researched and developed.

In-situ combustion (ISC) is the oldest thermal-recovery technique. It has been used for more than nine decades for many successful projects. This method is basically the injection of an oxidizing gas (air- or oxygen-enriched air) to generate heat by burning a portion of resilient oil. Most of the oil is driven toward the producers using a combination of gasdrive, steam, and waterdrive.

High temperatures and the presence of corrosive gases involved during the ISC process can present significant challenges during well isolation.

Phosphate cement is a unique system capable of resisting corrosive attack, maintaining low permeability at high temperatures, and resisting the attack of carbonic acid.

One of the primary challenges was developing a special phosphate cement slurry capable of setting at low temperatures to minimize the waiting on cement (WOC) as well as developing properties sufficient for resisting future stresses. A special sodium aluminate thixotropic additive was used for the first time to react chemically with the pH of this special cement system to develop a quick and high compressive strength.

More than nine wells have been cemented with this system in Colombia with good results. These wells have been subjected to different stresses (production, steam injection, and ISC). This paper presents the successful application of advanced non-Portland cement slurry within the Quifa heavy oil reservoir in Colombia utilizing an ISC enhanced recovery method

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