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Collaborating Authors
Results
Abstract A North Sea Field has been water flooded with commingled produced and aquifer water since 1997. Low- sulphate source waters were selected for injection in order to mitigate barium sulphate scaling and reservoir souring development. Small volumes of seawater are included in the injection water due to operational reasons, but the average sulphate concentration of the overall injection water does not exceed 20 mg/l. Aquifer and produced water has historically been injected with minimal treatment due to the high permeability of the clastic reservoirs. Despite the low sulphate concentration of the injection water there has been souring development over field life. The reservoir temperature of 104 F is sufficiently low to allow microbiological activity throughout the reservoir. Microbiological monitoring in the produced fluids indicates the presence of sulphate-reducing bacteria (SRB), but the low sulphate availability limits SRB activity. The injection water was treated with continuous biocide with the intention of controlling SRB activity within the reservoir, and reservoir souring simulations were carried out to investigate the effectiveness of this treatment. The simulation results indicated that the levels of H2S present in the produced water were consistent with the availability of sulphate in the injection water, and that the biocide treatment was not limiting SRB activity. The continuous biocide treatment was discontinued and no subsequent increase in H2S generation was observed in the field, demonstrating that souring development was sulphate limited.
- North America > United States (0.68)
- Europe > United Kingdom > North Sea (0.61)
- Europe > Norway > North Sea (0.61)
- (3 more...)
- Geology > Mineral > Sulfate (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock (0.34)
- Energy > Oil & Gas > Upstream (1.00)
- Water & Waste Management > Water Management > Lifecycle > Disposal/Injection (0.47)
- Water & Waste Management > Water Management > Constituents > Bacteria (0.34)
- North America > United States > Oklahoma > Anadarko Basin > L Formation (0.99)
- North America > Canada > Alberta > Peak Field > Cdn-Sup Et Al Zaman 10-14-119-5 Well (0.98)
- Africa > Middle East > Libya > Murzuq District > Murzuq Basin > Block NC 186 > Field A Field > Silurian Tanezzuft Formation (0.98)
- Africa > Middle East > Libya > Murzuq District > Murzuq Basin > Block NC 115 > Field A Field > Silurian Tanezzuft Formation (0.98)
- Reservoir Description and Dynamics > Improved and Enhanced Recovery > Waterflooding (1.00)
- Production and Well Operations > Production Chemistry, Metallurgy and Biology > Corrosion inhibition and management (including H2S and CO2) (1.00)
- Health, Safety, Environment & Sustainability > Environment > Water use, produced water discharge and disposal (1.00)
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 Large quantities of seawater are injected in oil and gas fields for pressure support and sweeping efficiency of the reservoir. This injection enhances the hydrocarbon recovery. Many difficulties are induced by sea water injection, such as the risk of sulfate based scale formation like barium sulfate precipitation. Seawater contains around 2800 mg/L of sulfate and some reservoir water may contain large quantities of barium and strontium. When those two waters are mixed into the reservoir, precipitation will occur and reduce the efficiency of water injection. In the producer wells, scale deposits may significantly reduce oil production. This is why technical solutions are more and more implemented to remove sulfate from the sea water before injection. Filtration processes using nanofiltration membranes are able to reduce the sulfate content of seawater, and this technique has been successfully operated for more than 12 years on several TOTAL offshore sites. The use of nanofiltration membranes requires an efficient pretreatment of seawater in order to control the fouling that will reduce the capacity of the sulfate removal unit over time. The only way to remove this fouling and recover the capacity of the unit is to stop a part of the unit and operate a chemical cleaning of the membranes. Biological fouling appears to be predominant on nanofiltration membranes for this application. As a consequence, preventing biofilm growth is a key aspect to increase availability of those units and can also be of interest for corrosion management. This paper presents the main results of experiments carried out by TOTAL on a sea water filtration pilot. Biofilm measuring probes have been tested in order to detect as soon as possible a change in the growth rate of the biofilm. Results demonstrated that such tools could be implemented in order to detect a default in the biofilm prevention strategy. This early detection tool will enable to react before the full system (all trains) requires a chemical cleaning in place. The eventual objectives of this tool are to maximize reliability of desulfated water injection, to optimize use of chemicals, to increase nanofiltration membrane lifetime, and facilitate field operation of such units.
- Africa (0.29)
- North America > United States (0.28)