Effect of Surfactant and Hydrophobe Content on the Rheology of Poly(acrylamide-co-N-dodecylacrylamide) for Potential Enhanced Oil Recovery Application

Associating polyacrylamide polymers have found profound use in the oil industry for Enhanced Oil Recovery (EOR) due to their improved rheological properties compared with ordinary non-associating polymers. Polymer rheology is important as it controls the mobility ratio of the displacing fluid to the displaced fluid and this can be severely affected by the high temperature and salinity present in most oil reservoirs resulting in loss of viscosity and viscous fingering of the displaced fluid. With associating polyacrylamide polymers, the presence of hydrophobic blocks on the polymer backbone allows for stronger intermolecular interaction between the polymer chains thereby improving its rheological behavior under harsh conditions obtainable in most oil reservoirs. In this project, polyacrylamide containing N-dodecylacrylamide was synthesized via micellar copolymerization in order to investigate the effect of hydrophobe variation and surfactant variation on the rheology of the prepared copolymers. Rheological measurements were carried out with the use of a Bohlin Rheometer. Improved viscous characteristics were observed with increasing hydrophobe content especially when polymer concentration exceeds the Critical Aggregation Concentration (CAC). This is due to larger hydrophobic blocks on the polymer backbone. Improved polymer viscosity was also observed when surfactant was added below its Critical Micelle Concentration (CMC.) This is as a result of the creation of mixed micelles of surfactant and hydrophobic blocks. This allows for an optimum polymer and surfactant concentration to be determined for poly (acrylamide-co-N-dodecylacrylamide) for potential application in Alkaline Surfactant Polymer (ASP) flooding involved in Enhanced Oil Recovery (EOR) projects

Poly (AM-co-N-DDAM): Investigating the Effects of Shear, Temperature and Salinity for Enhanced Oil Recovery Application

Polymer degradation is an important challenge associated with polymer flooding operations during Enhanced Oil Recovery (EOR). Non-associating polymers lose their viscosity under harsh reservoir conditions such as high temperature and salinity. This makes for an inefficient recovery process under such conditions. Polyacrylamide based associating polymers has been an area of ongoing research as the use of different hydrophobic co-monomers with acrylamide monomers yields associating polymers with improved rheological properties. In this paper, an associating polymer made up of acrylamide (AM) and N-dodecylacrylamide (N-DDAM) was synthesized via micellar copolymerization with the amount of N-dodecylacrylamide co-monomer varied for each synthesized polymers. The characterization of the synthesized polymer was carried out through viscometric measurement using an Ubbelohde Viscometer to determine the molecular weight of the polymers. The rheological behavior of the polymers under shear stress, temperature and salinity was investigated using a Bohlin Rheometer. Improved rheological properties were observed with increasing amount of the N-dodecylacrylamide co-monomer. The effect of the N-dodecylacrylamide content can be seen in the improved resistance to salinity, shear and temperature comparable with most hostile environments of oil reservoirs. These enhanced polymeric properties turn out to be more evident when the N-dodecylacrylamide content increases which leads to larger hydrophobic blocks on the polymer backbone. The presence of these N-dodecylacrylamide blocks on the polymer backbone increases its molecular weight thereby improving its viscous propert

Security assessments of IEEE 802.15.4 standard based on X.805 framework

One such wireless technology used to deploy sensitive network services requiring low rate communication, short distance application with low power consumption is the IEEE802.15.4 Low-Rate Wireless Personal Area Networks (LR-WPAN). These network services have stringent security requirements and, irrespective of the scale of deployment, the network should be secure enough to protect users, infrastructure, network services and applications. In this paper, we focus on the security mechanisms defined in the standard;evaluating it in the light of the ITU-T recommendation X.805 security architecture for end-to-end communication. We identify and assess the security dimensions, planes and layers in IEEE802.15.4 LR-WPAN as defined in the X.805 framework

Multicast Scheduling and Resource Allocation Algorithms for OFDMA-Based Systems: A Survey

Multicasting is emerging as an enabling technology for multimedia transmissions over wireless networks to support several groups of users with flexible quality of service (QoS)requirements. Although multicast has huge potential to push the limits of next generation communication systems; it is however one of the most challenging issues currently being addressed. In this survey, we explain multicast group formation and various forms of group rate determination approaches. We also provide a systematic review of recent channel-aware multicast scheduling and resource allocation (MSRA) techniques proposed for downlink multicast services in OFDMA based systems. We study these enabling algorithms, evaluate their core characteristics, limitations and classify them using multidimensional matrix. We cohesively review the algorithms in terms of their throughput maximization, fairness considerations, performance complexities, multi-antenna support, optimality and simplifying assumptions. We discuss existing standards employing multicasting and further highlight some potential research opportunities in multicast systems

Dependence of Outage Probability of Cooperative Systems with Single Relay Selection on Channel Correlation

The relay selection method is a promising technique for improving the performance of cooperative systems. Most of the existing studies assume that wireless channels are statistically independent. However, in reality, channel correlation is more likely to be non-negligible. In this study, we investigate the dependence of the performance of cooperative systems with single relay selection in equally correlated environments. A tight upper bound of the system outage probability is given as a function of the channel correlation coefficients. We show that even though the system performance is considerably degraded in the high signal-to-noise ratio (SNR) region when the channel correlations are sufficiently large, yet less than one, the system still achieves a diversity order equal to the number of available relays

Predictive modelling of the impact of silica nanoparticles on fluid loss of water based drilling mud

Research into the use of nanoparticles for drilling mud formulation is gaining momentum but a key challenge involves predicting the effect of nanoparticles on the properties of the modified mud. Mathematical models used in the description of drilling muds allow for a generalised computation of drilling performance. In other words, such models cannot quantitatively capture the contributions of nanoparticles to the overall performance of the nano-modified drilling mud. In this work, a new model was derived which describes the fluid loss of nanoparticle enhanced water based drilling mud under static filtration. This was done taking into account the structural kinetics of the bentonite suspension and colloidal behaviour of the nanoparticles.The new fluid loss model was compared with the known API static fluid loss model using statistical measures,Root Mean Square Error (RMSE) and Coefficient of Determination (R2). The new model compares favourably with the API static model with RMSE and R2 values of 0.41–0.81 cm3 and 99.3–99.89% respectively.The new fluid loss model was able to predict a value for the maximum fluid loss. It also accounted for variation in mud cake permeability and solid fraction, which could not be explained by the API fluid loss model

Characterizing Geometrical Anisotropy of Petrophysical properties in the middle Shahejie formation, Liaohe Depression, China.

Knowledge of reservoir body lateral extent is important information for estimation of hydrocarbon initially in place and the recoverable quantity. This study reports a stepwise approach to evaluate geometrical anisotropy of the rapidly changing alluvial fan Shahejie formation of Eocene age. This is towards understanding reservoir geometry of the deposit beneath the flank of Bohai bay, Northern China. Computation of Sand net to gross (Volume of shale), porosity and permeability was done on well logs as an initial analytical step, followed by computation of sample variograms, data transformation and property modeling. Computation of semivariance was based on first geometrical anisotropy for autocorrelation by finding major and minor directions of data consistency. Autocorrelation of data with distance of location made upscaled data useful for stochastic simulation. Minor data direction is almost perpendicular to the major direction with the bandwidth of not less than 4000. In the vertical direction, average bandwidth is 50. Porosity for the modeled zone is consistent with values between 17% and 35%. Permeability is consistent briefly away from well location but higher in shale units. These oil impregnated shale units are laterally consistent in the up-dip portion but were overtaken by the clastic units in the distal portion. This made draining of hydrocarbon better done in the down-dip portion of the area. An excellent comparative analysis was made of the litho-facies model, petrophysical properties, and inversion results obtained from the vintage seismic. This has yielded a good result in characterizing variation in rock properties of the subtle laterally inconsistent synsedimentary lithofacies of this ar

Evaluating the Oil Mobilization Properties of Nanoparticles Treated with Arabic Gum and Xanthan Gum for Trapped Oil in Porous Media

The flow of multiple fluid phases in porous media often results in trapped droplets of the non-wetting phase. Recent experimental and theoretical studies have suggested that nanoparticle aqueous dispersions may be effective at mobilizing trapped droplets of oil in porous media. Hypotheses to explain the observation include the nanoparticles' modification of solid wettability, changes in interfacial tension and interface rheology. The difficulty in observing droplet behavior on the pore scale has made the understanding of such mechanism still unclear. In this work, the relationship between nanoparticle concentration and microscopic diversion of flow was investigated and how this impacts on the oil mobilization efficiency. Also investigated in this work was how the rheology of the dispersion medium for nanoparticles impacts on the overall recovery of trapped oil in porous media. A core flooding experiment was carried out on which aqueous solutions of different concentrations of the nanoparticle dispersion was used as the displacing fluid likewise rheological modified solutions of the nanofluids. The output of this work showed that the nanoparticle concentration impacts on the recovery of trapped oil through the microscopic diversion of fluid flow in porous media and this phenomenon in conjunction with earlier mention hypothesis effectively showed how nanoparticles enhances the recovery of trapped oil in porous media

Properties and application of Nigerian bentonite clay deposits for drilling mud formulation: Recent advances and future prospects

The vast deposits of Nigerian bentonite clay have many significant uses in different aspects of industrial fields of which the oil and gas industry is a potential consumer of this clay mineral. In this review article, the key mineralogical characteristics and rheological properties of these clay deposits in various locations and their related application for drilling mud formulation were comprehensively reviewed. Various research efforts on these bentonite clay deposits over the past couple of years were summarized with some critical comments and analysis. Attention was given to the clay reserve estimates, mineralogy of the clay deposits, chemical modification of the clays, rheological properties of drilling mud formulated from these clays and its suitability for drilling operations. Moreover, future prospects and key problems to be solved regarding the use of Nigerian bentonite deposits for drilling mud formulation were discussed. This review shed new light on both fundamental and practical studies that are concentrated on the use of Nigerian bentonite for drilling mud formulation

Dataset on the beneficiation of a Nigerian bentoniteclay mineral for drilling mud formulation

This paperpresentsdatasetonthebeneficiation ofaNigerianclay mineral fordrillingmudapplication.Theexperimentaldesign applied usedaResponseSurfaceDesign(RSM),whichinvolved24 (2-Level, 4-Factors)togeneratestatisticalmodels,andanalyzethe dataset. Theindependentvariableswere(Bentonite; X1), (Polymer; X2), (SodiumCarbonate, X3) and(AgingTime; X4). Therheological properties ofinterest,whichformstheresponsevariables,were selected basedontheAPIspecification 13-Afordrillinggrade bentonite.Theoutcomesshowthatthesecond-orderstatistical models derivedfromresponses fitted wellwiththeexperimental results. Predictivemodelsobtainedfromthestatisticalcharacter- ization ofthebeneficiation processwouldallowforthedesignand cost-effectiveplanningoftheprocedure.Thebeneficiation ofthe clay usingsodiumcarbonateandKelzans XCDpolymerensuedin an improvementintherheologicalpropertiesoftheformulated drilling mud.ThesepropertieswerecomparablewiththeAPI specification 13-Afordrilling fluid material