Wisup Bae

A Review of Polymer Conformance Treatment: A Successful Guideline for Water Control in Mature Fields

Abstract Waterflooding has been practiced for several decades as a means of secondary recovery. This process is successful if there is uniform resistance to the injected water. However, due to its nature of heterogeneity, the injected water flows to the less resistant path, resulting in poor sweep efficiency. As one of many candidates to overcome this problem, polymer systems mixing with several types of chemical agents have been researched and applied for several years. In this article, the authors reviewed and summarized the Relative Permeability Modification/Disproportionate Permeability Reduction and water shutoff treatments.

Investigation of Isotherm Polymer Adsorption in Porous Media

The injection of chemical solutions plays an important role in increasing the recovery factor of mature fields. Chemical flooding is considered as an attractive alternative to conventional waterflooding; it can improve the area sweep efficiency not only at the macroscale but also in the microscale by control mobility of displaced fluid. Adsorption of polymer in reservoir rock is an extremely important parameter for chemical flooding. Adsorption represents a loss of chemical agent from solution and, consequently, a net reduction in the surfactant–polymer slug. Therefore, the efficiency of polymer flooding is significantly diminished both technically and economically. However, numerical simulation of multicomponent adsorption is still limited and adsorption processes in a polymer–rock system have not yet been well developed, especially for highly heterogeneous reservoirs. In this article, adsorption was modeled by the Langmuir isotherm theory. The simulation results indicated that polymer adsorption strongly depends on polymer concentration, shear rate, pH, salt concentration, and reservoir heterogeneity. Effective control of such parameters can reduce the effect of polymer adsorption to minimize chemical loss and improve the economic efficiency of chemical flooding processes.

A Review of Steam Generation for In-Situ Oil Sands Projects

ABSTRACT Steam Assisted Gravity Drainage (SAGD), an unconventional enhanced oil recovery process for the oil sands, is getting more attention recently as the international oil price increases rapidly. Basic concept of SAGD is to extract the viscosity-lowered bitumen by high pressure, high temperature 100% quality steam injected into the reservoir containing high-viscosity bitumen. As its name implies, generation of high-quality, high-temperature and high-pressure steam is a prerequisite for the SAGD process. Hence in this paper, key aspects of steam generation system for oil sands recovery will be broadly reviewed to provide the engineers concerned with the working principles and the major issues such as configuration, design, control of steam generation system used for oil sands recovery.

An Investigation of Hybrid Steam-Solvent Injection for Increasing Economy and Reducing CO2 Emission

The hybrid steam-solvent injection scheme has been applied but limited results have been reported in the literature. The optimum solvent concentration to maximize economics and to reduce the CO2 emission is still in question. A synthetic reservoir model was developed using real field data to study such an injection. Results indicate that the optimal solvent concentration is 5.0% by volume fraction and as the concentration increases the CO2 emission reduces. The optimum case has 21% gain in the net present value discounted by 12% per annual and 9.1% reduction in the CO2 emission comparing to the pure steam injection.

A Review of Practical Experience and Management of the SAGD Process for Oil Sands Development

Abstract With the fluctuation of international oil prices due to limited conventional petroleum resources, unconventional energy, including bitumen and extra heavy oil, are of primary interest these days. However, in-situ recovery processes of these resources are somewhat complicated, and there are many technical challenges accompanying it. For the recovery process, it is widely known that thermal techniques using steam are essential in reservoir heating. Especially, the steam-assisted gravity drainage process is a leading technology in the development of oil sands. This article presents the steam-assisted gravity drainage process for the production of oil sands by reviewing and analyzing several authors and companies.

Sensitivity analysis for fault reactivation in potential CO2-EOR site with multi-layers of permeable and impermeable formations

CO2-EOR is considered as a promising solution for enhanced oil recovery (EOR) and is attracting attention as being a more economical CO2 geological sequestration solution along with oil recovery enhancement. However, injecting CO2 at high pressure may cause many geomechanical changes and potential instabilities in surrounding formation such as ground uplift, caprock fracturing, and nearby fault reactivation. Such instabilities could significantly influence the stability of both surface facilities and subsurface structures. Especially, miscible CO2-EOR, by which recovers more oil than immiscible one but, uses less CO2, requires an injection pressure exceeding the minimum miscible pressure (MMP), which is determined by characteristics of reservoir conditions and oil compositions. Thus, for successful and safe CO2-EOR operation, injection pressure interval between MMP and the maximum pressure that could be tolerated from geomechanics safety concerns should be appropriately designed considering site-specific reservoir conditions. In this study, we perform a numerical simulation of coupled multiphase fluid flow and geomechanical analysis using TOUGH-FLAC simulator for the potential CO2-EOR site in Indonesian oil field, and demonstrate how much fault reactivation is sensitive to fault structure, slip-weakening property of faults, reservoir permeability, and in situ stress conditions. The model site consists of impermeable shale and permeable sandstone reservoir units so that the potential for fault slip through this multilayered formation is highlighted in the simulations. Our simulation results showed that fault slip initiation can be reached earlier period when in situ stress is anisotropic and reservoir is more permeable, because the stress state at the faults is near the frictional strength limit and the pore pressure buildup reaches to the fault much faster. The analysis shows that multilayered formations with high- and low-permeability layers are advantageous in CO2-EOR since intense pore pressure buildup and subsequent fault reactivation could be impeded by pressure dissipation in high-permeability layers. However, we noted that fault reactivation may become substantial when the fault has a slip-weakening property and the residual frictional coefficient of the site-specific fault is very low.

Controlling the hybrid steam-solvent injection for increasing recovery factor and reducing solvent retention in heterogeneous reservoirs

The irregular steam chamber propagation has been a problem in hybrid steam-solvent injection in heterogeneous reservoirs. When the steam chamber is poor, the solvent passes through to the production well directly. If the steam chamber is good, the oil drain will be effective. In such a case, controlling the hybrid steam-solvent injection is necessary to spread the steam chamber uniformly. A synthetic reservoir model was developed to study the phenomenon using a real field data set. Adjusting steam injection pressure, grouping perforations, and controlling the openings of perforation were observed. The adjustment from the peak of production rate is more favourable because the steam chamber has reached its maturity. Then, the solvent effectiveness increases and the solvent retention reduces. The heat efficiency and recovery factor are increased by 7.4% and 8%, respectively. The NPV on the adjustment from the peak of production rate increases by 9% compared with no-adjustment case. [Received: January 21, 2015; Accepted: May 27, 2015]

Numerical Simulation of SAGD Recovery Process in Presence of Shale Barriers, Thief Zones, and Fracture System

This study presents a numerical investigation for evaluating the potential applicability of the steam-assisted gravity drainage (SAGD) recovery process under complex reservoir conditions such as shale barriers, thief zones with bottom and/or top water layers, overlying gas cap, and fracture systems in the McMurray and Clearwater formation. The simulation results indicated that the near-well regions were very sensitive to shale layers, and only long, continuous shale barriers (larger than 50 m or 25%) affect the SAGD performance in these well regions. In addition, the thief zones had a strongly detrimental effect on SAGD. The results also showed that the SAGD recovery process was enhanced in the presence of vertical fractures but horizontal fractures were harmful to recovery. Fracture spacing is not an important parameter in the performance of a steam process in fractured reservoirs and extending horizontal fractures will reduce ultimate oil recovery in the SAGD process. This article provides a guideline for SAGD operations in complex geological reservoirs.

Enhanced Oil Recovery (EOR) Technology Coupled with Underground Carbon Dioxide Sequestration

Abstract Enhanced oil recovery (EOR) technology coupled with underground carbon dioxide sequestration is introduced. CO 2 can be injected into an oil reservoir in order to enhance oil production rate and CO 2 EOR can be turned into CCS in a long term sense. Coupling CO 2 EOR with CCS may secure a large scale and consistent CO 2 source for EOR, and the CO 2 EOR can bring an additional economic benefit for CCS, since the benefit from enhanced oil production by CO 2 EOR will compensate costs for CCS implementation. In this paper, we introduced the characteristics of CO 2 EOR technology and its market prospect, and reviewed the Weyburn CO 2 EOR project which is the first large-scale CO 2 EOR case utilizing an anthropogenic CO 2 source. We also introduced geotechnical elements for a successful and economical implementation of CO 2 EOR with CCS and they were a miscroseismic monitoring during and after injection of CO 2 , and determination of minimum miscible pressure (MMP) and maximum injection pressure (MIP) of CO

Gelation Time Optimization for an HPAM/Chromium Acetate System: The Successful Key of Conformance Control Technology

Abstract Gelation of gelant solutions occurs under specific conditions. The gelation time can vary from several minutes to several days, even a few months, depending on parameters, such as temperature, polymer type, polymer concentration, cross-linker concentration, initial pH, salt type, and salt concentration. Therefore, many laboratory experiments were studied to understand the gelation time before the core flooding experiments were carried out. The polyacrylamide polymers and the chromium acetates were mixed to form the gelant solutions. The results suggested the good proportion of polymer to cross-linker for the next core flooding experiments and the effects of gelation time.