Carbon Dioxide in Situ Generation for Enhanced Oil Recovery

Abstract

Carbon dioxide flooding of oil fields around the world is proven as a successfully adopted practice in increasing oil production particularly in marginal wells with low production rates. However, the limitations of this technology lie in the limited supply of carbon dioxide, high capital cost, and infrastructure corrosion. In this work, we present an alternative CO2 flooding method which generates CO2 inside the reservoir to increase oil recovery. The process involves the injection of a concentrated CO2 producing solution of ammonium carbamate (AC). Chemical solvent CO2 capture technology was widely used for years. Carbamates were formed when aqueous amines absorbed CO2. The new proposed in situ CO2 generation EOR technique provides a way to directly apply the product of the CO2 capture technology for outstanding tertiary recovery. Ammonium carbamate (CH6N2O2), highly water-soluble chemicals, can dissociate at reservoir temperature producing carbon dioxide and ammonia. The carbon dioxide migrates to the oil phase, causing oil phase swelling and reducing oil viscosity, and therefore increasing oil production. The ammonia dissolves in the water, and the ammonia-water solution increases the water wettability of the rock. Flow experiments were conducted using 6" Ottawa sand packs. The experiments demonstrated that the decomposition of a 35% AC solution injected to the sand packs resulted in further lowering of the residual oil saturation following a standard water flood. The tertiary recovery in the high-pressure sand pack experiments was found to average 27%. In the proposed process, AC can be dissolved in produced reservoir fluids or seawater and injected into the reservoir to generate CO2 in situ and increase oil production as it decomposes. The benefits of this process compared to CO2 flooding lie in the simplicity of adapting this technology to an existing waterflood, and the lack of the complicated infrastructure needed in a typical CO2 project, such as compression and gas handling facilities. An additional advantage lies in the ability to deliver the CO2 in the form of a room temperature solid, alleviating the need for a pipeline.

Experimental study on the enhanced oil recovery by in situ foam formulation

“…Self‐generated gas technology can effectively solve the storage and transportation problems of gas sources in offshore platform operation. Some early studies have proved its feasibility as a chemical flooding technique for enhanced oil recovery . For example, Wang used urea and ammonium carbamate as reaction agents for the in situ CO 2 technology.…”

“…For example, Wang used urea and ammonium carbamate as reaction agents for the in situ CO 2 technology. They found that the in situ CO 2 technology was close to the complex combination flooding technology such as surfactant recovery and alkali flooding in terms of tertiary oil recovery . In addition, the effects of injection method, agent concentration, and high divalent ion level on the reaction kinetics and recovery performance of the urea system were also investigated .…”

“…Some early studies have proved its feasibility as a chemical flooding technique for enhanced oil recovery. [25][26][27][28][29][30][31][32] For example, Wang used urea and ammonium carbamate as reaction agents for the in situ CO 2 technology. They found that the in situ CO 2 technology was close to the complex combination flooding technology such as surfactant recovery and alkali flooding in terms of tertiary oil recovery.…”

“…They found that the in situ CO 2 technology was close to the complex combination flooding technology such as surfactant recovery and alkali flooding in terms of tertiary oil recovery. [25][26][27] In addition, the effects of injection method, agent concentration, and high divalent ion level on the reaction kinetics and recovery performance of the urea system were also investigated. 28,29 Zhu et al 30 used an acid-alternating base (AAB) system to generate CO 2 for blockage removal and enhanced oil recovery.…”

A numerical simulation study of CO2 injection for enhancing hydrocarbon recovery and sequestration in liquid-rich shales

“…Even with current stimulation and completion technologies, many fields are expected to produce less than 10% of initial oil in place. CO 2 -enhanced oil recovery (EOR) for liquid-rich unconventional reservoirs has been investigated through core flooding (Wang et al 2017) and field 'huff-n-puff' pilot tests (Hoffman and John 2016). Our literature survey shows that field applications of enhanced oil recovery (EOR) for unconventional oil reservoirs are limited.…”