Project: Development of new heavy-duty nanofiltration technology for re-injection of produced water in off-shore oil field production.
Water injection has been used for several decades to increase oil recovery from reservoirs. The technology is now used worldwide and the trend is that as oil recovery is decreasing the water cut production will increase steeply. For example, in the Danish North Sea the annual water production is around 40 mill. m3 and expected to increase by 20 % until 2013. As a consequence of increasing water injection, elevated risk of souring (i.e. H2S production with the oil reservoir) and increasing discharge of oil polluted water to the sea is expected. Handling increased amounts of produced water cut is therefore a major challenge for the oil industry._x000D__x000D_Advanced filtration technologies can provide solutions for a range of problems encountered in offshore water systems. Among potential advantages are decreased scaling and reservoir plugging, decreased degree of souring by the use of produced water re-injection (PWRI), decreased chemical consumption of scavengers and inhibitors, overall improving economy, working environment and the aquatic environment. However, due to technical constraints, cost and energy consumption advanced filtration technology is not widely used in the European oil industry. _x000D__x000D_The combination of offshore filtration and PWRI may potentially solve problems of oil field souring and lowering the environmental impact of discharging produced water. Therefore, new filtration technologies need to be developed to exploit the potential benefits listed above. These filters should meet requirements such as:_x000D__x000D_• Robust design that can resist a harsh environment with elevated pressure and temperature and ignitable gases._x000D_• High performance, compact design and small foot-print for offshore installation._x000D_• Resistance towards chemicals and oil components._x000D_• Removal of small particles that causes scaling and plugging in reservoirs._x000D_• Lowering and/or removal of sulfate for mitigation of souring in offshore oil fields._x000D__x000D_The objective of this joint European project is development of such filter technology based on silicon carbide (SiC) ceramic membranes. Various coatings will be included to cover the range of pore sizes needed when dealing with produced water re-injection and preparation of injection water - ranging from micrometer-sized particles and oil droplets down to sulfate ions. The project will address technology development, documentation of effect and capacity. A technical evaluation of overall benefits and drawbacks will also be conducted._x000D__x000D_The significance of water handling challenges is broad, comprising i.) effects on the aquatic environment e.g. discharge of oil components with produced water, ii) safety issues such as risk of failures due to corrosion caused by H2S and microbes, risk of H2S leakage and handling of chemicals etc. and iii) economic loss due to e.g. devaluation of sour oil, cost of chemicals such as H2S scavengers and scale inhibitors and increased corrosion of the production system. However, two key points allow us to reduce the overall negative impact:_x000D__x000D_1. Filtration of produced water enables re-injection of produced water. Produced water re-injection reduces both hydrocarbon-discharge to sea as well as sulfate input to reservoir and associated souring. Hence, it is preferred to re-inject produced water to the highest possible degree. To enable this, particles and oil droplets should be removed, as they may plug the reservoir formation and reduce injectivity._x000D__x000D_2. Decreasing sulfate input to the reservoir reduces availability of sulfate and thereby reducing microbial H2S-production (souring) and chemical scaling. Lower sulfate input can be obtained by nanofiltration of sea water. Nanofiltration of seawater is energy consuming, and therefore it is optimal to filtrate only a minimal amount of makeup water as supplement to produced water._x000D__x000D_In this project, technologies for these two points will be developed and demonstrated. Furthermore, the potential of an integrated water management approach applying both of these technologies will be analyzed in depth through business cases and evaluation of benefits and limitations of filtration technologies._x000D__x000D_The outcome of the project is expected to be new filtration technologies for application in the oil and gas industry. The potential for savings on chemical consumption is expected to be significant and furthermore it will have positive effect on both work and external environment. An evaluation of integrated applications of filtration technology in oil and gas industry will comprise costs, benefits and limitations. The project will therefore provide an increased understanding of alternative methods for mitigation of scaling and souring and provide a better strategy to meet future economical and environmental requirements along with increased water production.
| Acronym | PW nanofiltration (Reference Number: 5555) |
| Duration | 01/01/2011 - 01/05/2014 |
| Project Topic | Development of filtration technology for injection water and produced water offshore. New solutions for sulfate removal and produced water re-injection will lead to minimized hydrocarbon discharge and souring of oil fields. |
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Project Results (after finalisation) |
The project was succesfull in demonstrating the use of new filtration technologies on a pilot and laboratory scale. This was performed by a new approach for produced water re-injection in the offshore oil industry and is expected to have a beneficial output with respect to environmental impact of the oil production. Concurrently, a reduction in the consumption of production chemicals can be achieved. It was demonstrated in the project that removal of sulfate by nanofiltration from the injection water will reduce microbiological souring in oil fields. However, the nanofiltration membrane for sulfate removal was not fully developed for application on a pilot scale. Furthermore, it was in the project described that particle filtration can be implemented full-scale in minor oilfields with some adjustments of the capacity. A joint technical paper was elaborated together with LiqTech International A/S with the following abstract: “With increasing water injection to enhance oil recovery in mature oil fields follows increasing discharge of produced water. Therefore, an emerging technology for lowering discharge of produced water and for controlling reservoir souring was investigated. Reservoir souring is caused by sulfate-reducing prokaryotes that have negative impact on oil-producing facilities, environment, and safety. Lowering the SO42– concentration in a reservoir may prevent severe H2S production and a better effect of the injected biocides and chemicals can be obtained. The aim of the current project was to develop a ceramic membrane capable of lowering SO42- concentrations, while COtaining the positive characteristics of the ceramic membrane (thermal and chemical resistance and high flux). The effect of lowering SO42– concentrations artificially was evaluated by filtration of produced water from an onshore oilfield with severe H2S concentrations (10 g l–1). Following filtration, produced water was diluted to obtain final SO42– concentrations of 240, 94, and 45 mg l–1. Anaerobic incubations conducted at the reservoir temperature of 54 oC showed that depletion of SO42– lowered H2S production rates by 45, 36, and 21 mg l–1 d–1, respectively. This showed that filtration can be applied as a tool for lowering biogenic souring. For development of a ceramic membrane for SO42– removal, a SiC 40 nm membrane was used as support. This membrane is currently applied for produced water filtration and re-injection (PWRI), lowering the oil contents to < 3 ppm. Applying new coating techniques, pore sizes <10 nm has been achieved, but to use SiC materials for SO42– removal pore sizes as low as 2 nm are required. This can be achieved by building a nanolayer consisting of ¿-Al2O3 on a SiC substrate, a technology currently being investigated. Potentially, this filtration technology can be a solution for use with PWRI for lowering produced water discharge and mitigation of souring in oil fields.” |
| Network | Eurostars |
| Call | Eurostars Cut-Off 4 |
Project partner
| Number | Name | Role | Country |
|---|---|---|---|
| 3 | Danish Technological Institute | Partner | Denmark |
| 3 | LiqTech International A/S | Coordinator | Denmark |
| 3 | TOTAL S.A. | Partner | France |