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Results
Abstract Treating water for injection in an offshore environment has always been challenging. As injection water quality becomes more stringently specified to maximize oil production across a wide range of reservoir geologies, the technical and economic complexity of treating the water dramatically increases. The more stringent treatment can include fine filtration to improve injectivity, specific ion treatment such as sulphate, calcium, magnesium removal to reduce precipitation risks and/or to enable chemical EOR, low salinity treatment for IOR/EOR, and deaeration to very low levels of oxygen to reduce corrosion. One of the most significant aspects of this added complexity is the inherent weight and footprint of the various unit operations of the water treating facilities that are necessary to achieve rigorous treatment. The weight and footprint of these facilities directly impacts capital costs, which in turn affects the economic viability of greenfield projects and, to an even larger degree, dictates the feasibility of brownfield improvements. The need for robust, lightweight and compact water treatment technologies for offshore injection has driven innovations in filtration, desalination, softening, sulphate removal, and deaeration. Relative to existing conventional seawater injection facilities composed of media filtration followed by vacuum tower deaeration, the subject innovations achieve an approximate 50 and 90% reduction in footprint and weight, respectively. A number of these technologies have recently undergone pilot and field testing to improve their technology readiness levels prior to full-scale commercialization, and to demonstrate capital costs savings. In addition, operating costs were evaluated. This paper presents the performance results of the pilot and field tests of two of these compact technologies: high production reverse osmosis membranes, and membrane deaeration. In addition to performance results, weight and footprint reductions associated with the technologies are provided to demonstrate the expected savings.
- Energy > Oil & Gas > Upstream (1.00)
- Water & Waste Management > Water Management > Lifecycle > Treatment (0.49)
Abstract Chemical enhanced oil recovery (EOR) provides the means to increase oil production through manipulation of the chemical and fluid properties within a given reservoir. The number of chemical EOR projects being developed, pilot tested, and commercially implemented is on the rise as a function of the relative decrease in chemical costs, advancements in chemical performance, more precise subsurface modeling, and recent stable oil pricing. The amount of calcium and magnesium (hardness) in the injection water plays a critical role in determining the type and dosage of alkali, surfactant, co-solvents and/or polymer (ASCP) used in a chemical EOR flood. The hardness dictates whether alkali can be used and affects the surfactant adsorption, achievable viscosity at specific polymer dosages, polymer stability, polymer choice as a function of thermal stability, as well as emulsion stability in the produced water. The ability to remove hardness and thereby use soft injection water with chemical EOR is a game changer, in that it can enable chemical floods that are otherwise uneconomic, infeasible or that are considered too risky. Soft water, invariably, comes at a cost related to treating the source water to remove calcium and magnesium. Source water for a chemical EOR flood is dictated by availability and environmental constraints and is usually limited to produced water, seawater or brine from deep aquifers. Occasionally, a surface water source is available. This paper reports on representative chemical EOR project case studies in seawater, brackish water and produced water applications at various sites and capacities. The cost of water softening is weighed against the reservoir and production benefits, culminating in a side-by-side economic analysis for each case study based on cost per incremental barrel of oil. The results can be used to guide the development of new chemical EOR projects in determining facility needs as a function of economics.
- Research Report (0.48)
- Overview (0.34)
- Reservoir Description and Dynamics > Improved and Enhanced Recovery > Waterflooding (1.00)
- Reservoir Description and Dynamics > Improved and Enhanced Recovery > Chemical flooding methods (1.00)
Abstract Water-based Enhanced Oil Recovery (EOR) technologies such as Low Salinity Flooding (LSF), Chemical EOR (CEOR), and steam-flooding have been growing in popularity over the years, and are generating new opportunities for the water treatment sector as a result. Water treatment technologies have the unique capability to address equipment and system requirements which are characteristic of EOR projects. However, these technologies typically have little to no history of application in the upstream oil and gas industry. This limited level of experience may impact EOR project budgets and schedules, particularly in offshore applications where weight and footprint availability are of critical value. In Southeast Asia, two offshore projects are investigating the use of customized water to maximize oil recovery in CEOR applications. In the first project, two CEOR programs consisting of vastly different water quality cocktails are under consideration, one of which incorporates produced water into its water source. In the second project, injection water quality with an ultra-low hardness level is desired, in order to prevent potential precipitation in the reservoir. In both cases, water treatment infrastructure must be capable not only of producing the intended injection water quality, but it must do so consistently in response to potential changes in the quality of the source water used. This paper describes the results of pilot testing of two typical water treatment technologies, Reverse Osmosis (RO) and unique nanofiltration membranes, to produce a variety of injection water chemistries for CEOR and LSF applications. These applications include ultra-low hardness, high salinity; and low hardness, low salinity injection water. The testing confirms the ability of new water treatment technologies to solve challenging issues that arise in EOR applications, particularly those in offshore applications that must respond to varying needs of reservoirs and footprint/weight limitations.
- Asia (0.89)
- North America > United States (0.69)
- Geology > Geological Subdiscipline (0.77)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock (0.30)
- Water & Waste Management > Water Management > Lifecycle > Treatment (1.00)
- Energy > Oil & Gas > Upstream (1.00)
Abstract There are various membrane technologies available in the marketplace today to tailor water quality to the specific needs of an enhanced oil recovery (EOR) operation. Membrane technology has been proven and used offshore in the sulphate removal process (SRP) since DOW Filmtec and Marathon first introduced the membrane system in 1991. By the end of 2008, SRP systems were installed on over 44 offshore production facilities around the world. The changing needs of the oil and gas industry are dictating the development of new technologies and the application of proven technology in novel ways to meet the industry demand. These new applications and technologies have the potential to impact production on a global scale. For instance, optimizing water chemistries throughout a CEOR flood by carefully choosing membrane and polishing technologies can favorably change CEOR project economics and therefore further enhance oil recovery by expanding the number of reservoirs globally in which CEOR is economically attractive. This paper will discuss what can be achieved with today's technology and the results from recent pilot testing of RO technology adapted from brackish water applications to be used to selectively remove ions for seawater-based EOR applications.
- North America > United States (1.00)
- Asia > Middle East (0.68)
- Reservoir Description and Dynamics > Improved and Enhanced Recovery > Waterflooding (1.00)
- Reservoir Description and Dynamics > Improved and Enhanced Recovery > Chemical flooding methods (1.00)
Abstract Chemical enhanced oil recovery (CEOR) is emerging as a vital method to increase recoverable oil from aging reservoirs, but economics and the achievable incremental recoverable oil will dictate its widespread adoption. Water chemistry of the injectant plays an important role in the effectiveness and cost of CEOR. For instance, in polymer floods using partially hydrolyzed polyacrylamides (PHPAM), it is well established that the realizable viscosity for a given polymer concentration is a function of the injection water salinity, with divalent cations having a more detrimental impact than monovalent ions. Studies have shown that five to ten times less PHPAM is required using desalinated or lower salinity water when compared to seawater, resulting in an equivalent cost savings related to polymer consumption. In surfactant flooding, the relationship between the injectant water chemistry and the effectiveness of the flood is a more complex equation. Considerable research is ongoing to predict optimal salinities for surfactant flooding and the added benefit of using salinity gradients through the life of the surfactant flood. And lastly, alkalinity addition to either a surfactant and/or polymer flood dictates the injectant water be softened to prevent calcium and magnesium carbonate precipitation if sodium carbonate is the source of cost-effective alkalinity. Further complicating matters, the injection water salinity must be kept at a level sufficient to prevent clay swelling in the reservoir, and sulfate levels must be low enough to prevent precipitation of the sparingly soluble salts of barium or strontium, if present. This paper analyses the economics associated with an alkalinity-surfactant-polymer (ASP) flood using general characteristics of an ASP flood project and demonstrates how optimizing the water quality of the injection water can change the project economics. Creating customized water chemistries of optimal blends throughout the CEOR flood is possible by carefully choosing membrane and polishing technologies which allow for a range of possible chemistries. Reducing the cost of CEOR through optimized water chemistries may further enhance oil recovery on a global scale by expanding the number of reservoirs in which CEOR is economically attractive.
- North America > United States (0.46)
- Asia > Malaysia (0.28)
- Asia > Middle East (0.28)
- Geology > Mineral > Silicate > Phyllosilicate (0.50)
- Geology > Rock Type > Sedimentary Rock (0.48)
- Geology > Mineral > Sulfate (0.36)
- Water & Waste Management > Water Management > Lifecycle > Treatment (1.00)
- Materials (1.00)
- Energy > Oil & Gas > Upstream (1.00)
- Reservoir Description and Dynamics > Improved and Enhanced Recovery > Waterflooding (1.00)
- Reservoir Description and Dynamics > Improved and Enhanced Recovery > Chemical flooding methods (1.00)