Induced migration of fines during waterflooding in communicating layer-cake reservoirs

The effects of fines migration induced by injection of water with a different salinity than the reservoir brine are incorporated into the upscaling model for waterflooding in a layer cake reservoir with good communication between the layers. Mobilization and re-capturing of the reservoir fines may give rise to reduction of the permeability in water swept zones, which subsequently leads to the diversion of water flow from the initially more permeable layers to the less permeable ones. As a result, the displacement is more even, the water cut at the producer is decreased, and the oil recovery is increased. On the other hand, more energy for the pressure drop is required to maintain a constant flow rate. These effects are studied within a new upscaling model developed previously (Zhang et al., 2011). In a communicating layer cake reservoir, higher end-point mobility ratio (water to oil) leads to more crossflow between layers and lowers the water sweep efficiency. However, this ratio facilitates the fluid diversion caused by the fines migration, leading to a more efficient enhanced oil recovery. The positive contribution from the mobility ratio to the increased oil recovery due to fines migration seems to be limited

Internal filtration and external filter cake build-up in sandstones

Water injection is an integral constituent of most field development scenarios. This injection may take place for secondary recovery and pressure maintenance such as sea water injection. Alternatively, it may take place as a waste water disposal method as in the case of produced water re-injection. Associated with most injection schemes is injectivity decline; where the rate of injection decreases over time at a given constant injection pressure gradient. The phenomenon of injectivity decline is comprised of multiple phenomena such as internal filtration, external filter cake build-up, fracture propagation, relative phase changes within the matrix rock and the associated permeability decline due to each of the described phenomena. The study presented in this thesis addresses some of the key phenomena associated with injectivity decline. Two sub-categories were studied both experimentally and theoretically: internal filtration and external filter cake build-up.Civil Engineering and Geoscience

Assessing the reliability and validity of the child abuse potential inventory in Arabic language among pregnant women in Oman

Background: The Child Abuse Potential Inventory (CAPI) is a screening tool, for assessing a parent’s potential towards child physical abuse. It was originally developed in English (Milner, 1986) and later translated to many different languages (Milner and Crouch 2012) but never in Arabic. This thesis aims at producing an Arabic version of the CAPI and assessing its psychometric properties, reliability and validity among a population of pregnant women in Oman. Methods: Following the development of an Arabic version, the CAPI was administered twice to a population of pregnant women (N= 309) attending Ante Natal Care Clinics in Muscat. A sub-sample of 10 mothers was later interviewed to explore their views and the acceptance of the tool in Oman. Results: The mean score of the Abuse Scale was 159.6 (range 26-390) which was higher than the American version (mean = 91) but similar to other cross-cultural versions. Internal consistency (Cronbach’s α= 0.91) and test-retest reliability (Pearson’s r= 0.89; two-tailed P 0.00) were both high. Regarding construct validity, the six-factor structure of the original version was not replicated; only three factors were obtained. The conservative cutoff score for the upper 5% of the parent sample was 303, which was higher than the cut-off score of 215 in the original US version. From the interviews, mothers reported that the CAPI was easy to complete and appropriate for use in Oman. Conclusions: The Arabic version of the CAPI showed highly satisfactory internal consistency and test-retest reliability. The construct correspondence with the original version was more compromised. This suggests that the Arabic version of the CAPI is a valid and reliable tool to use to assess potential towards child physical abuse within Oman, but with different cutoff scores. These results are in concordance with other cross-cultural versions of the CAPI. Further research is needed to validate an Arabic version of the CAPI in relation to actual parenting outcomes

The value and Development of Soft Skills for Sultanate of Oman

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Injectivity Decline Under Multiple Particle Capture Mechanisms

SPE paper 98623Severe injectivity decline during seawater injection and produced water re-injection is a serious problem in offshore waterflood projects. The permeability impairment occurs due to capture of particles from injected water by the rock. The reliable modelling-based prediction of injectivity decline is important for the injected-water-treatment design, for injected water management (injection of sea- or produced water, their combinations, water filtering), etc. The classical deep bed filtration model accounts for a single physics mechanism of the particle capture. During laboratory or field data interpretation using this model, it is usually assumed that several simultaneously occuring capture mechanisms are represented in the model by a single overall mechanism. The filtration coefficient as obtained by fitting the model to the laboratory or field data represents the total kinetics of the particle capture. Nevertheless, the kinetics of different capture mechanisms can differ one from another by several orders of magnitude. It highly affects the particle propagation in natural reservoirs and the formation damage. A multiple retention deep bed filtration model describes several simultaneous capture mechanisms. In the present study, a model for deep bed filtration taking into account multiple particle retention mechanisms is discussed. It is proven that the multi capture model can be reduced to a single-capture-mechanism deep bed filtration model. The method for determination of the capture kinetics for all individual capture processes from the breakthrough curve is discussed. As an example, the complete characterisation of filtration with monolayer and multilayer deposition of iron oxide colloids is performed using particle breakthrough curves from coreflooding

Deep-Bed filtration under multiple particle-capture mechanisms

© 2009 Society of Petroleum EngineersSummary Severe injectivity decline during seawater injection and produced-water reinjection is a serious problem in offshore waterflood projects. The permeability impairment occurs because of the capture of particles from injected water by the rock, both internally in the pores and externally in a filter cake. The reliable modeling-based prediction of injectivity decline is important for injected-water-treatment design and management (injection of seawater or produced water, water filtering, etc.). The classical deep-bed filtration model includes a single overall description of particle capture. During laboratory or field data interpretation using this model, it is usually assumed that several simultaneously occurring capture mechanisms are represented in the model by a single overall mechanism. The filtration coefficient, obtained by fitting the model to the laboratory or field data, represents the total kinetics of the particle capture. The purpose of this study is to justify this approach of using an aggregated single filtration coefficient. A multiple-retention deep-bed filtration model needs to describe several simultaneous capture mechanisms. The kinetics of the different capture mechanisms can differ from one another by several orders of magnitude. This greatly affects the particle propagation in natural reservoirs and the resulting formation damage. In this study, a model for deep-bed filtration taking into account multiple particle-retention mechanisms is discussed. It is proven that the multicapture model can be reduced to a single-capture-mechanism deep-bed filtration model. The method for determination of the capture kinetics for all individual capture processes from the breakthrough curve is discussed. As an example, the complete characterization of filtration with monolayer and multilayer deposition of iron oxide colloids is performed using particle-breakthrough curves from coreflooding.Rafael G. Guedes, Firas A.H. Al-Abduwani, Pavel Bedrikovetsky, Peter K. Curri

External filter cake erosion: mathematical model and experimental study

SPE paper 94635In this article a system of equation to describe the steady state external filter cake thickness profile along the cuboid crossflow filtration setup geometry as well as the well bore geometry are introduced. The first equation is obtained from the analysis of forces acting on a deposited particle at the outermost limit of the external cake. The second equation is obtained from the volume conversation of the transporting fluid in the given geometry. Coupling the two equations yields an implicit solution of the cake profile. Boundary conditions are required as well as the quantification of an empirical factor that can be quantified experimentally. Experiments conducted were analysed and the empirical friction coefficient was quantified and presented. Simulations based on the developed solution are also presented. Copyright 2005, Society of Petroleum Engineers.Al-Abduwani, F., Bedrikovetski, P., Farajzadeh, R., van den Broek, W.M.G.T. and Currie, P. K.http://www.proceedings.com/00161.htm

External filter cake erosion: mathematical model and experimental study

SPE paper 94635In this article a system of equation to describe the steady state external filter cake thickness profile along the cuboid crossflow filtration setup geometry as well as the well bore geometry are introduced. The first equation is obtained from the analysis of forces acting on a deposited particle at the outermost limit of the external cake. The second equation is obtained from the volume conversation of the transporting fluid in the given geometry. Coupling the two equations yields an implicit solution of the cake profile. Boundary conditions are required as well as the quantification of an empirical factor that can be quantified experimentally. Experiments conducted were analysed and the empirical friction coefficient was quantified and presented. Simulations based on the developed solution are also presented. Copyright 2005, Society of Petroleum Engineers.Al-Abduwani, F., Bedrikovetski, P., Farajzadeh, R., van den Broek, W.M.G.T. and Currie, P. K.http://www.proceedings.com/00161.htm