Low Salinity Waterflooding (LSF) is a rapidly emerging IOR/EOR technology that improves oil recovery by lowering the injection water salinity. A membrane-based desalination process provides additional advantages such as reduction of souring, scaling and it can prevent injectivity decline. Proper screening of LSF for a particular field requires performing laboratory SCAL tests to (i) measure relative permeability curves to enable field-scale quantification of the LSF benefits by modeling and (ii) de-risk the potential of formation damage through clay swelling and deflocculation. Salym Petroleum Development (SPD; JV Shell/GazPromNeft) is actively looking into IOR/EOR methods to increase the water flood recovery factor. While ASP is being matured as the main EOR option, several LSF laboratory tests have been performed recently to assess the potential of this technique for West Salym. A key LSF enabler in the area is the presence of large, relatively low-saline aquifers in the vicinity of the field, which can serve as a plentiful source of low salinity (LS) injection brine. This study focuses on the initial Salym LSF SCAL tests performed at reservoir conditions, using representative reservoir core and crude oil, with synthetic brines that reflect the formation and injection water compositions accurately. The experiments comprised a suite of Amott and coreflood tests, following the internal Shell LSF protocol. The tests clearly show a positive LSF effect, with additional oil produced in absence of formation damage. The data indicates that LSF causes a shift in wettability towards a more water-wet behavior, and results in a reduction of Sorw. Upscaling the core flood results to field scale indicated that incremental recoveries within the life time of the field could be 1.7% of oil initially in place (OIIP) in tertiary mode, while a secondary mode LSF scheme would have increased the oil recovery over the same time by almost 4% of OIIP.
Low-salinity waterflooding (LSF) has been recognized as an IOR/EOR technique for both green and brown fields in which the salinity of the injected water is lowered for particular reservoir properties to improve oil recovery. While providing lower or similar UTC's low salinity projects have the advantage of lower capital and operational costs as compared to some more expensive EOR alternatives.This work describes LSF experiments, field-scale simulation results, and conceptual design of surface facilities for West Salym oil field. The field is located in West Siberia and is on stream since 2004. Conventional waterflooding was started in 2005 and current water cut is currently above 80% in the developed area of the field. To counter oil production decline a tertiary Alkaline-Surfactant-Polymer (ASP) flooding technique selected for mature waterflooded field parts and piloting of this technique is ongoing. Operationally simpler and more cost-effective LSF method is considered for implementation in the unflushed (green) areas of the field since it has been recognized that application of LSF in secondary mode results in better incremental oil recovery than LSF in tertiary mode.The results of a comprehensive conceptual study performed to justify the LSF trial are presented in this paper. To generate production forecast for LSF in the isolated area at the outset of reservoir development the results of laboratory core tests executed at different salinities presented earlier have been used. Dynamic reservoir modelling using low-salinity relative permeability curves showed that injection of low-salinity water leads to incremental oil production up to 2.5% of STOIIP. These results establish the fundamentals for a LSF field trial. A concept of surface facilities design for LSF trial area at West Salym oil field is also presented in the paper. Differently to other LSF projects it is proposed to prepare low-salinity water with required properties by mixing fresh water from aquifer and high salinity water from produced water reinjection (PWRI) system. In such a case LSF facilities concept does not require expensive water treatment techniques which significantly reduces the project capital and operational costs.
With decreasing size the density of electronic states of a metal particle becomes different from that of the bulk. This significantly changes the behaviour of the thermodynamic properties of such a particle. We present specific heat and spin susceptibiblity measurements on a series of chemically synthesized Pd particles with diameters of 2.4-15 nm and magnetic measurements on a Ni colloid with an average diameter of about 2.8 nm. Pronounced size dependence of the electronic magnetic properties was found which is accompanied by only weak size dependence of the electronic specific heat. This result can be understood in terms of a size-dependence of the Stoner enhancement factor, which only enters into the susceptibility and not into the specific heat.
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