Natal dispersal is a well-studied phenomenon that can be divided into three stages: (1) starting from an area, (2) wandering to another area and (3) either settling in that area to breed or merely temporarily stopping there before continuing to wander. During the third phase, we can distinguish breeders from non-breeders, which may show similar or different patterns of space use. Breeding Common Ravens are territorial year-round; non-breeders are highly vagrant but may gather at food sources and night roosts for varying lengths of time. In contrast to the wandering phase, little is known about the space use of ravens at such ''stop'' sites. Here, we used radio telemetry to investigate the space use of 21 non-breeding ravens in the Austrian Alps during a stop stage at an anthropogenic food source. The tagged ravens were present in 69.2 % of the relocation attempts. They used only 27.0 ha (range 6.7-59.7 ha, 95 % utilisation distribution) of the study area, and their activity ranges strongly overlapped with each other. However, within this shared space, sub/adult non-breeders could be found at individually distinct locations, while juveniles showed similar spatial distributions. These results, combined with reported long-distance movements, underline the high behavioural flexibility of non-breeding ravens, which may be a reason for their success in very different habitats throughout the Northern Hemisphere.
For the first time ever a novel biopolymer is being field tested in a mature onshore oil field in Northern Germany. This biopolymer – named Schizophyllan after its producing fungus – shows excellent viscosifying efficiency and high tolerance towards harsh reservoir conditions such as high temperature, salinity and shear. Hence, this biopolymer allows for application in reservoirs that could so far not be polymer flooded and extends the operating envelope for polymer flooding to temperatures up to 275°F at arbitrary salt contents. Furthermore, it provides an environmentally friendly alternative to the commonly used synthetic polymers. To run this first field test petroleum engineers of Wintershall Holding GmbH, chemical research scientists and biotechnologists of BASF SE are closely cooperating in an integrated team. An existing biotechnological plant at the BASF compound in Ludwigshafen, Germany, was partly reconstructed into a production facility for providing sufficient biopolymer for the field pilot. In the oil field itself an existing production site was extended into an operation site also hosting the surface facilities for treatment of the produced water used for re-injection and preparation of the injected biopolymer solution. Being trucked to site as mother solution the Schizophyllan is mixed on-the fly with the treated, high-salinity reservoir brine and injected into a newly drilled injector in the project area surrounded by three production wells. A comprehensive surveillance program was set up comprising regular microbiological sampling, pressure monitoring using permanent down-hole gauges as well as frequent analyses and production tests to monitor the progress of the polymer trial. The paper presents further information on the biopolymer Schizophyllan, describes the preparation and the setup of the field trial and summarizes results and experiences from the first year of the two-year field trial.
Wintershall is conducting a technology project for development and field application of MEOR (Microbiologically Enhanced Oil Recovery) in collaboration with BASF. The successful results of the laboratory phase led to a first small confined pilot Huff'n’ Puff (HnP) in a Wintershall mature oil field to prove that the laboratory-developed concept works in the field under reservoir conditions. A suitable well for the MEOR operation was selected in the studied field based on selection criteria. The selected well is a former producer approximately 900 m deep. After a USIT run it was decided to recomplete it. Prior to MEOR HnP pilot, an injectivity test was performed to allow for re-assessment of the current petrophysical and geological properties around the well. In order to establish the baseline for the pilot evaluation, a comprehensive monitoring program consisting of microbiological, chemical and petrophysical surveys commenced just after the well recompletion. The surface set-up designed for follow-up MEOR field operations was installed in the field. The mixing of the MEOR solution with the injection water was regulated automatically by measuring the injection rate. The injection took four days, followed by an incubation period of five weeks. During the nutrient injection, the injectivity was significantly lower than the one obtained from a previous injectivity test. As a result, the total volume of injected nutrient was lower than initially planned. Nevertheless, the volume was sufficient to achieve the pilot objectives. The injection was carried out under matrix conditions by keeping the pressure below the fracture pressure. The injected fluid temperature was somewhat lower than planned, but according to downhole measurements, still high enough for microbial growth. It was observed that there was an oxygen ingress into the system through the injection pump, however no detrimental effect was seen on microbial activity. After the shut in period, a comparable volume of the injection fluid was produced back. The tracer concentration in the back produced fluid was used to calibrate the chemical and microbiological effects of MEOR.
A new class of viscoelastic solutions -Triphenoxmethanes (TPM)-has been under development since early 2010 and remain a fruitful yet highly challenging research topic. The TPM's are viscoelastic at low concentrations (<0.5%w/w) and show good stability in highly saline hard brines. They have been tested in hard brines up to 25% TDS with high divalent cation concentration and show increasing performance with increasing salinity. The current lead candidate "TPM", which is also being scaled up for a first field trial, displays good performance to 75°C. Adsorption/retention measurements show quite acceptable values for the harsh conditions under study. Porous media testing has shown that the TPM's have good injectivity properties and mobilize significantly more oil than brine alone. In addition, oil displacement experiments with cores at residual oil concentration (Sor) have clearly shown that TPM mobilizes residual oil (ca.7% OOIP) without significant reduction of the IFT and with less than 1 PV injected fluid. The suitability for use in a particular reservoir is a complex interplay of the molecular structure of the TPM, temperature and brine salinity: lowering the salinity increases the application temperature. The interrelationship of the different factors is an on-going, high priority activity of the integrated R&D team. Here we report on the relevant aspects for application in harsh environments and give an outlook for field application.
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