16 research outputs found
Two-phase flow of Newtonian and non-Newtonian fluids in a porous medium applied to water coning
No full textElectrical Engineering, Mathematics and Computer Scienc
Simulating fluid flow in hydrocarbon reservoirs - a scheme of sedimentologically defined flow-unit configurations demonstrated on deltaic rocks
No full textMathematical analysis of the influence of power-law fluid rheology on a capillary diffusion zone
No full textNon-Newtonian fluids are used in current oil recovery processes. These fluids do not satisfy the linear Darcy Law for flow through porous media. A generalization is needed to model the flow processes involved. Furthermore, when two immiscible fluids are present in a porous medium, capillary pressure will cause a transition zone to develop between them. This transition zone may lead to early breakthrough of water into an oil well. In this paper, we study the effect of the non-Newtonian behaviour of fluids on a capillary transition zone. A general framework is set up for modelling processes involving two-phase flow of non-Newtonian, immiscible and incompressible fluids in a porous medium. The equations are applied to the one-dimensional diffusion process of power-law fluids. The model allows for general capillary pressure and relative permeability functions. The mathematical model consists of a degenerate diffusion equation, giving rise to a free boundary formulation. The free boundaries represent the endpoint of the diffusion zone. Qualitative properties, and some analytical solutions, can be obtained for the saturation profile. Two numerical methods are presented. One is applicable if the rheology of both fluids is modelled with equal powers. The other is applicable to the general situation. Both methods make use of the qualitative, analytical properties of the solutions, which clearly improved the results obtained by standard methods. One-dimensional results can be used to interpret the general multi-dimensional flow behaviour of non-Newtonian fluids when capillarity is considered. They can also be used to test numerical algorithms developed for multi-dimensional displacement processes
An integrated approach of gene expression and DNA-methylation profiles of WNT signaling genes uncovers novel prognostic markers in Acute Myeloid Leukemia
No full textBackground The wingless-Int (WNT) pathway has an essential role in cell regulation of hematopoietic stem cells (HSC). For Acute Myeloid Leukemia (AML), the malignant counterpart of HSC, currently only a selective number of genes of the WNT pathway are analyzed by using either gene expression or DNA-methylation profiles for the identification of prognostic markers and potential candidate targets for drug therapy. It is known that mRNA expression is controlled by DNA-methylation and that specific patterns can infer the ability to differentiate biological differences, thus a combined analysis using all WNT annotated genes could provide more insight in the WNT signaling. Approach We created a computational approach that integrates gene expression and DNA promoter methylation profiles. The approach represents the continuous gene expression and promoter methylation profiles with nine discrete mutually exclusive scenarios. The scenario representation allows for a refinement of patient groups by a more powerful statistical analysis, and the construction of a co-expression network. We focused on 268 WNT annotated signaling genes that are derived from the molecular signature database. Results Using the scenarios we identified seven prognostic markers for overall survival and event-free survival. Three genes are novel prognostic markers; two with favorable outcome (PSMD2, PPARD) and one with unfavorable outcome (XPNPEP). The remaining four genes (LEF1, SFRP2, RUNX1, and AXIN2) were previously identified but we could refine the patient groups. Three AML risk groups were further analyzed and the co-expression network showed that only the good risk group harbors frequent promoter hypermethylation and significantly correlated interactions with proteasome family members. Conclusion Our results provide novel insights in WNT signaling in AML, we discovered new and previously identified prognostic markers and a refinement of the patient groups.Intelligent SystemsElectrical Engineering, Mathematics and Computer Scienc
