Ricardo AEA (Germany)

Correction for ‘Influences on and patterns in total gaseous mercury (TGM) at Harwell, England’ by J. Kentisbeer et al., Environ. Sci.: Processes Impacts, 2015, DOI: 10.1039/c4em00652f.

Summary In this paper we review progress made in developing United Kingdom Continental Shelf (UKCS) heavy oil fields. Reservoir productivity is compared with existing light oil developments and three categories of heavy oil reservoir are identified, which require the application of different well technologies to achieve acceptable offshore production rates. Case histories from existing developments and fields under appraisal are used to illustrate how advances in technology and effective risk management allow increasingly difficult heavy oil fields to be developed. Finally, the future direction for these heavy oil developments is discussed, looking at the scope for improved oil recovery (IOR) techniques and further technology developments to drive down costs and to increase reserves in fields currently under waterflood or to improve the economics of hitherto subeconomic fields.

Measurements and Simulation of Inertial and High Capillary Number Flow Phenomena in Gas-Condensate Relative Permeability Robert Mott; Robert Mott AEA Technology Search for other works by this author on: This Site Google Scholar Andrew Cable; Andrew Cable AEA Technology Search for other works by this author on: This Site Google Scholar Mike Spearing Mike Spearing AEA Technology Search for other works by this author on: This Site Google Scholar Paper presented at the SPE Annual Technical Conference and Exhibition, Dallas, Texas, October 2000. Paper Number: SPE-62932-MS https://doi.org/10.2118/62932-MS Published: October 01 2000 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Get Permissions Search Site Citation Mott, Robert, Cable, Andrew, and Mike Spearing. "Measurements and Simulation of Inertial and High Capillary Number Flow Phenomena in Gas-Condensate Relative Permeability." Paper presented at the SPE Annual Technical Conference and Exhibition, Dallas, Texas, October 2000. doi: https://doi.org/10.2118/62932-MS Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAll ProceedingsSociety of Petroleum Engineers (SPE)SPE Annual Technical Conference and Exhibition Search Advanced Search AbstractThe productivity of most gas condensate wells is reduced significantly by condensate banking when the bottom hole pressure falls below the dew point. The most important parameter for determining condensate well productivity is the effective gas permeability in the near well region, where very high velocities can occur. An understanding of the characteristics of high-velocity gas-condensate flow is necessary for accurate forecasts of well productivity. A number of laboratory experiments have demonstrated that gas condensate relative permeabilities increase at high velocity, reducing the negative impact of condensate banking on well productivity. On the other hand, inertial (non-Darcy) flow effects can reduce the effective gas permeability and lead to lower productivity.This paper presents results of relative permeability measurements on a low permeability sandstone core, using a 5-component gas-condensate fluid. The experiments used a pseudo-steady-state technique at high pressure and high velocity, measuring relative permeability under conditions similar to the near-well region of a gas-condensate reservoir.By carrying out measurements at a range of interfacial tensions and velocities, the results can be used to distinguish between high capillary number and inertial flow effects, and to quantify the impact of these two conflicting phenomena. The experiments suggest that the inertial flow coefficient in a 3-phase gas-condensate-water system is about 50% higher then in the equivalent 2-phase gas-water system.The results of these experiments have been modelled through a correlation of relative permeability versus capillary number, together with an inertial flow correction to the gas permeability. The paper discusses these models and demonstrates how they can be used to calculate gas-condensate well performance in full-field reservoir simulation.IntroductionWell productivity is an important issue in the development of many gas-condensate reservoirs. Accurate predictions of well productivity are needed to select the best development plan, to optimise the number of wells and to set gas sales contracts.When the well bottom hole flowing pressure falls below the dew point, a condensate bank forms near the well, impairing the flow of gas and reducing productivity. Condensate saturations as high as 50 or 60 per cent can be attained in the near-well region, reducing gas productivity by up to an order of magnitude. The most important parameter for determining the impact of condensate blockage is the effective gas permeability in the near-well region.Most of the pressure drop from condensate blockage occurs within a few feet of the well bore, where the gas phase will be flowing at a high velocity. An understanding of the characteristics of high-velocity gas-condensate flow is necessary for accurate forecasts of well productivity.In the flow of gas-condensate fluids through porous media at high velocities, there appear to be two competing phenomena which may cause the effective gas permeability to be rate-dependent.An increase in relative permeability with velocity, which has been demonstrated in numerous laboratory core flood experiments1,2,3,4,5,6,7,8. This effect is sometimes termed 'velocity stripping' or 'positive coupling'.Inertial (non-Darcy) flow effects, which reduce the effective gas permeability at high velocity.These two high-velocity phenomena act in opposite directions. Velocity-dependent relative permeability has the effect of improving well productivity, while inertial flow reduces the effective gas permeability and leads to lower productivity. At the flow rates in typical gas-condensate wells, it appears that the change in relative permeability has a much larger impact, so that the overall effect of these high-velocity phenomena is an improvement in productivity. Keywords: fluid dynamics, productivity, flow in porous media, gas permeability, correlation, production monitoring, flow rate, experiment, reservoir simulation, relative permeability Subjects: Well & Reservoir Surveillance and Monitoring, Reservoir Fluid Dynamics, Reservoir Simulation, Formation Evaluation & Management, Flow in porous media This content is only available via PDF. 2000. Society of Petroleum Engineers You can access this article if you purchase or spend a download.

Abstract Well deliverability in most gas condensate reservoirs is reduced by condensate banking when the pressure falls below the dew point, but the impact of condensate banking may be reduced due to improved mobility at high capillary number in the near-well region. Fevang and Whitson1 have shown that the key parameter in determining well deliverability is the relationship between krg and the ratio krg/kro. They also suggested an experimental technique for measuring krg as a function of krg/kro using core plugs. We have applied the experimental pseudo-steady-state technique proposed by Fevang and Whitson to long cores at high pressure and temperature, measuring relative permeabilites under conditions which are similar to the near-well region of a gas condensate reservoir. A gas condensate fluid is introduced into a core whose pressure is below the dew point of the fluid. The condensate saturation in the core builds up until it becomes mobile and a steady state is reached, reproducing the mechanism which occurs in the reservoir. By varying the fluid composition, core pressure and flow rate, it is possible to measure all of the relative permeability data needed to predict well deliverability, including the increase in mobility at high capillary number. We describe the experimental techniques and present results for a sandstone core from a North Sea gas condensate reservoir, using a 5-component synthetic fluid. The results show a clear increase in mobility with capillary number, at flow rates which are typical of the near-well region. The pseudo-steady-state technique measures relative permeabilities and does not require saturations to be measured. The dependence of krg on krg/kro can be used directly in pseudopressure methods to calculate well deliverability. We also describe how the data for krg versus krg/kro can be used to define parameters for empirical correlations of relative permeability versus saturation, so that the results can be used in reservoir simulators.

The Sempa project brings together researchers from computer science, mechanical engineering, and numerical analysis to define software-engineering methods for the parallelization of existing large-scale software packages in scientific computing. The parallel implementation of TfC, an industrial state-of-the-art computational-fluid-dynamics simulation program, serves as the central case study for defining and evaluating these methods. Sempa researchers have successfully implemented and tested a portable parallel version of TfC based on message-passing standards (PVM and MPI). In addition, Sempa researchers have demonstrated the potential of new languages and programming paradigms such as data parallelism and object orientation by reimplementing the algebraic multigrid solver-a key module in TfC-in Fortran 90, HPF, and C++. Networks of workstations have become very attractive as low-cost platforms. Efficiently using their resources for production runs of parallel software requires automated resource management that optimizes resource utilization for parallel batch jobs without impeding interactive use. Therefore, the Sempa project has also implemented a resource manager for batch execution of PVM programs.

<div class="htmlview paragraph">The combustion of diesel fuels injected into a bomb at 25 bar and 520°C has been modelled and studied experimentally using laser diagnostics. A CFD model of diesel spray injection was combined with a database of results from a detailed chemical kinetic model.</div> <div class="htmlview paragraph">All fuels showed the presence of small aromatics throughout combustion (i.e. the fuel aromatics were not completely broken down). The model gave good agreement on spray penetrations and soot volume fractions around the edges of the spray. Far from the spray, the model over-predicted the amount of soot due to the absence of an OH oxidation mechanism in the CFD code. This demonstrates the need to progress to the use of a reduced chemistry scheme.</div>

M. W. Wedd, C. J. Price, P. York, S. J. Maginn and J. W. Mullin, Anal. Proc., 1993, 30, 447 DOI: 10.1039/AP9933000447