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Collaborating Authors
Results
Thermo-Sensitive Nanogels for Targeted Tracer Release in Push and Pull Operations
Panneer Selvam, Arun Kumar (National IOR Center of Norway, University of Stavanger, Institute of Energy Technology) | Ould Metidji, Mahmoud (National IOR Center of Norway, Institute of Energy Technology) | Silva, Mario (National IOR Center of Norway, Institute of Energy Technology) | Krivokapic, Alexander (Institute of Energy Technology) | Bjørnstad, Tor (National IOR Center of Norway, Institute of Energy Technology)
Abstract The single-well chemical tracer test (SWCTT) is widely used in the determination of residual oil saturation (SOR) in the near-well region. SWCTTs typically require large amounts of chemicals and some days of well shut-down. In the present paper, we propose using thermo-sensitive nanogel carriers for targeted release of tracers for SWCTTs. This approach has the potential to significantly reduce the time and amount of chemicals required by a SWCTT. The targeted tracer release method was inspired by previously developed drug delivery applications using stimuli-sensitive nano-capsules. Nanoparticles loaded with medical cargo were synthesised to target specific sites. The release of the active principles would then be triggered by an in-situ (temperature, pH) or ex-situ (magnetic field, light) stimuli. A novative approach to address the current limitation of classical SWCTT is based on the biomedical background. It consists in using a poly-N-isopropylacrylamide (pNIPAm) based nanogel, known for its thermo-sensitive nature, to ensure the in-situ delivery of tracer molecules. This effect is explored as a mechanism to both load and release the tracers for a SWCTT. PNIPAm nanogels or hydrogels are highly hydrophilic, cross-linked polymeric networks. When the temperature of the solution is increased above the lower critical solution temperature (LCST) of PNIPAm molecule, the capsules exhibit a reversible collapse effect, causing the release of the tracer molecules. The hydrodynamic diameters of capsules were measured using Dynamic Light Scattering (DLS) and were found to be 195 nm at 25 °C and 73 nm at 45 °C. The nanogels exhibit a reduction in volume to 8 times when the temperature is increased from 25 °C to 45 °C. This change in volume acts as a lock-in mechanism once the tracer is loaded and open-up to release loaded tracers. The study of the encapsulation and release of tracer compounds was achieved using passive and partitioning tracers loaded into the structures. The capsules showed a significant tracer loading efficiency. For studying the release rate and mechanism, increase in temperature was used to trigger the release of tracers. Although the SWCTTs are the most used tracer tests by the oil industry, their development have been relatively slow since it was originally introduced in 1973 (Deans 1971). The present study aims at presenting a novel approach on how nanotechnology can be used to reduce the large amounts of chemicals and time required by classical SWCTTs. Concepts and results about the synthesis of the nano-carriers, loading and releasing of the tracers are presented and discussed.
- Europe (0.70)
- North America > United States > Oklahoma > Beaver County (0.24)
- Energy > Oil & Gas > Upstream (1.00)
- Materials > Chemicals > Commodity Chemicals > Petrochemicals (0.70)
- Reservoir Description and Dynamics > Improved and Enhanced Recovery (1.00)
- Reservoir Description and Dynamics > Formation Evaluation & Management > Tracer test analysis (1.00)
A Step-Change for Single Well Chemical Tracer Tests (SWCTT): Field Pilot Testing of New Sets of Novel Tracers
Al-Abbad, Mohammed (Saudi Aramco) | Sanni, Modiu (Saudi Aramco) | Kokal, Sunil (Saudi Aramco) | Krivokapic, Alexander (Institutt for Energiteknikk) | Dye, Christian (Institutt for Energiteknikk) | Dugstad, Øyvind ((Restrack)) | Hartvig, Sven ((Restrack)) | Huseby, Olaf ((Restrack))
Abstract SWCTTs are often used to assess residual oil saturation (Sor) or remaining oil saturation (ROS) in the near well-bore region before initiating enhanced oil recovery (EOR) or improved oil recovery (IOR) projects. The technique is based on the chromatographic separation of two different tracers. One oil/water partitioning tracer partly hydrolyzes in the reservoir, to generate a secondary non-partitioning water tracer. Most of the reported SWCTT operations typically use ethyl acetate (EtAc) as the primary tracer. Some of the challenges with the current set of chemicals used are their high flammability, poor detection limit (ppm range) and the large quantity required. A new set of tracers has been developed to overcome these challenges. These were pilot tested in a giant carbonate reservoir undergoing peripheral water-flood to measure Sor prior to a field redevelopment project. The new tracers were field tested concurrently with the conventional EtAc method for comparison purposes. About 100 g (0.1 kg) of each of the new tracers were injected at different times and different ways during the conventional SWCTT operation. It is worth highlighting that tens or hundreds of kilograms of conventional SWCTT tracer are needed for a single operation. This paper reviews the complete design and implementation of the test, operational issues, the analyses and the interpretation of the results. The Sor measured by each of the novel tracers compare well to that from a conventional SWCTT. The results also show that these tracers can be injected in pulse mode – at a very short time interval, thus reducing the operational time needed for pumping the chemicals. In addition, the test results suggest that several tracers with different partitioning coefficient may be deployed to investigate different depths of the reservoir. The pilot further demonstrate that many tracers with different properties may be deployed simultaneously without risking interference with the Sor measured during the test – this may revolutionize measurements of saturations in SWCTT operations.
- Asia > Middle East (0.94)
- Europe > United Kingdom > North Sea > Central North Sea (0.51)
- North America > United States > Texas (0.46)
- North America > United States > Texas > Fort Worth Basin > Ranger Field (0.99)
- Europe > United Kingdom > North Sea > Central North Sea > Central Graben > West Central Graben > PL2244 > Block 21/27a > Pilot Field (0.99)
- Europe > United Kingdom > North Sea > Central North Sea > Central Graben > West Central Graben > P2244 > Block 21/27a > Pilot Field (0.99)
- (13 more...)
- Reservoir Description and Dynamics > Improved and Enhanced Recovery (1.00)
- Reservoir Description and Dynamics > Formation Evaluation & Management > Tracer test analysis (1.00)