Overview: EOR/IOR (January 2008)

Abstract

Overview Currently available primary- and secondary-oil-production technologies leave behind two-thirds of the oil in place as stranded oil. However, many analysis and field projects have shown that significant oil-recovery increases are possible with improved/enhanced oil recovery (EOR) by gas injection, thermal recovery, or chemical injection. The first two methods have proved cost-effective even at low oil prices. Current oil prices have created renewed interest in more-costly chemical-based EOR methods such as gel treatment, foam flooding, polymer flooding, alkaline/surfactant/polymer (ASP) flooding, and alkaline flooding. This year, we focus on chemical-based EOR methods. Chemical-EOR methods focus on improving the sweep efficiency by correcting reservoir heterogeneity or controlling fluid mobility, or they focus on increasing displacement efficiency by reducing residual-oil saturation. Gel treatment usually is intended to improve sweep efficiency and to reduce excess water production in channeled or fracture-dominated mature reservoirs. A newer trend in gel treatment is to apply preformed gels for in-depth treatments. These gels have been reported to penetrate deeply into superhigh-permeability streaks or fractures and seal or partially seal them off, thus creating high flow resistance in formerly watered-out, high-permeability zones. When successful, these gel systems divert a portion of the injection water into areas not previously swept by water. Foam flooding often is used to reduce gas mobility and to correct reservoir heterogeneity and increase sweep efficiency for gasflooding. Foam can be injected into the reservoir by coinjection of gas and surfactant solution or by injection of surfactant solution alternating with gas (SAG). Foam stability, surfactant-adsorption reduction, and optimized SAG-process design are the keys to controlling the economics of foam flooding. Polymer flooding is designed to control mobility for waterflooding. High-molecular-weight and new high-temperature salt-resistant polymers have made polymer flooding more economical. Adding either an alkaline or surfactant chemical, or both, in a polymer flood will scour residual oil from the rock, resulting in higher oil recovery than with polymer flooding alone. However, the scale problem associated with alkaline limits the use of ASP flooding. Wettability is of major importance to oil recovery, especially for fractured oil-wet carbonate reservoirs where water flows through the fractures but does not imbibe into the matrix because of negative capillary pressure. The chief concern is to develop cost-effective chemical formulations that change the carbonate wettability from oil-wet to water-wet. EOR/IOR additional reading available at the SPE eLibrary: www.spe.org SPE 107095 "Field-Scale Wettability Modification—The Limitations of Diffusive Surfactant Transport" by W.M. Stoll, SPE, Shell International E&P, et al. SPE 107776 "Improved ASP Design Using Organic-Compound/Surfactant/Polymer for La Salina Field, Maracaibo Lake" by E. Guerra, PDVSA Intevep, et al. SPE 107727 "Polymer Flooding: A Sustainable Enhanced Oil Recovery in the Current Scenario" by Ivonete P. Gonzalez da Silva, Petrobras, et al. SPE 106901 "SAGD Optimization With Air Injection" by J.D.M. Belgrave, EnCana Corporation, et al.

Break-up of droplets in a concentrated emulsion flowing through a narrow constriction

“…In addition to droplet microuidics, the ow of concentrated emulsions through small constrictions in porous media is important to many industrial processes. [25][26][27][28][29] Processes such as mobility control in enhanced oil recovery depend critically on the viscoelastic properties of the emulsions or foams, which in turn depend on the microstructure of the uids involved. 26 The presence of many interfaces, the complexity, and the heterogeneity of the physiochemical characteristics of natural porous media-such as the oil reservoir-make it extremely challenging to predict the evolution of the microstructure of the injected uids and therefore their bulk rheological properties.…”

A comprehensive review of nanoparticles applications in the oil and gas industry

“…Due to the fact that two-thirds of the oil in place is left behind after the primary and secondary recovery (Bai 2008), and based on the significant increase observed in oil recovery using enhanced oil recovery techniques (EOR), which includes chemical injection, thermal recovery, and gas injection, a good number of researches have been conducted to improve the different EOR techniques by the addition of nanoparticles. Table 1 shows a summary of the recent investigations on the application of nanoparticles to enhance EOR techniques along with the targeted parameters and the investigated nanoparticles.…”