Nanotechnology has shown enormous progress in the petroleum industry especially in the area of Enhanced Oil Recovery. However, field experience has shown that the major challenge facing polymer flooding is polymer degradation under reservoir conditions such as high temperature and high salinity. Though Partially hydrolysed polyacrylamide (HPAM) is the current widely used polymer, it is also very sensitive to salinity, shear, thermal degradation due hydrolysis of polyacrylamide introduced as a result of negative charges on the backbones of polymer chains which in turn causes an alteration on the rheological properties of the polymer solution. The rheological behaviour for different solutions of Guar gum and Gum Arabic containing different salt was evaluated to study the effect of nanoclay and other additives on the stability of these biopolymers. The viscosity of these polymer solutions was measured using a rheometer and in each measurement, the shear rate was changed, and the effect of this change on the viscosity was measured. Results showed improved stability at different range of salinity and level of concentration of the polymers.
The oil industry is experiencing a paradigm shift where the use of green chemicals is being encouraged in order to address environmental issues associated with the use of synthetic chemicals and also because of the fact that most of these synthetic polymers like hydrolysed polyacrylamide used to improve mobility ratio in Polymer flooding are imported chemicals. Thus, the need to source for other polymers that are viable and equally environmentally friendly. Gum Arabic used in this analysis was obtained from the northern part of Nigeria. Different concentrations of Gum Arabic were analysed to study their rheology as well as the effect of salinity on them in order to determine their degree of resistance for this is a criterion in polymer flooding. However, the stability of Gum Arabic was further enhanced by the addition of Carboxymethyl Cellulose (CMC) at varying concentration to determine its effect on the solution viscosity. Based on the results, the effect of blending resulted in synergistic viscosity however, the stability of the solution with respect to the effect of salinity was affected. Eiroboyi et al.; CJAST, 36(4): 1-7, 2019; Article no.CJAST.49744 2 Original Research Article
In enhancing oil recovery through polymer flooding, the application of polymers have been basically structured around the use of commercial polymers like xanthan gum, scleroglucan, Hydroxyl ethyl cellulose, Polyacrylamide, Hydrolysed Polyacrylamide and its derivatives. The use of some of these polymer has led to negative environmental issues and also increased treatment cost prior to discharge. The cost of some of the polymers is another reason, their applicability have not been appreciated so much in the oil and gas industry. The adoption of the principles of green chemistry in the synthesis of chemicals is a sure way of ensuring pollution prevention rather pollution control. Analysis carried on these polymers showed good rheology especially at higher concentrations. The displacement efficiency of Locust bean gum (LBG) and Gum arabic were evaluated using 0.2wt% and 0.5wt% in hard brine to recover trapped oil after water flooding, the results reflected significant incremental recoveries from both the use of LBG and Gum Arabic which also correlated with rheological characterisation carried out under different saline conditions. This analysis was extended by carrying a comparative study with commercial Locust bean gum and Xanthan gum. The efficiency of locally sourced LBG and Gum Arabic revealed that they are both candidates for polymer flooding.
The use of dimensionless pressure and dimensionless pressure derivative type curves has fully overcome the challenges experienced in the use of straight line methods and has brought about major successes in well tests analyses. Flow periods and reservoir boundary types are easily delineated and identified with the use of these curves. Furthermore, near wellbore characterization results are now more reliable. In this study, type curves for a reservoir subject to bottom water energy and a vertical well completion are developed to reveal specific signatures that can be used to achieve efficient pressure test analysis. Both early and late flow periods were considered for a wellbore of negligible skin and wellbore storage influences. Results obtained show that dimensionless pressures depart from infinite-acting behavior and attain steady state at dimensionless time of order proportional to the square of dimensionless reservoir thickness. Wellbore dimensionless radius affects dimensionless time of attainment of steady state inversely, which is rather accelerated by large fluid withdrawal rates (large pressure drawdown). On the other hand, dimensionless pressure derivatives show gradual collapse to zero after expiration of infinite flow. The rate of collapse is strongly affected by wellbore properties and pressure drawdown. Radial flow is generally characterized by a constant slope of 1.151 during which period the dimensionless pressure derivative gave a value of 0.5. Following assumption of negligible wellbore skin and storage, no early time hump is observed on dimensionless derivative curves.
The stability of polymers used in enhanced oil recovery especially in polymer flooding is largely based on their ability to withstand challenging reservoir conditions such as the effect of high salinity and high temperature. Polymers like Hydrolysed Polyacrylamide (HPAM) and its derivatives lose their viscosity when subjected to high salinity conditions due to the screening of the ions of the polymer backbone chain. HPAM is not only sensitive to salinity and temperature but also very susceptible to shear degradation. Research show that Xanthan gum; a commercial biopolymer used mostly in polymer flooding show more tolerance to shear degradation and even better stability to salinity and temperature than HPAM but not frequently used due to its high cost. The work is centered on the study of stability of some selected low cost biopolymers like Guar gum, Locust bean gum, Gum Arabic as well as the commercial Xanthan gum. This study captures the effect of monovalent and divalent ions on the polymers in order to establish their degree of stability and the impact of these ions with respect to varying salinity conditions. The rheological performance of these polymers were analysed using both NaCl and CaCl under both medium and high saline conditions which are similar to reservoir conditions. The results show that all polymers show appreciable resistance and stability when compared to Xanthan gum especially Locust bean gum in the presence of monovalent ions, Gum Arabic displayed the least tolerance to the ions. Although, the presence of divalent ions had more impact than the monovalent ions on all polymers' stability, however, higher concentrations of the polymers resulted in more resistance to the presence of these ions.
This paper presents comparative analysis between the pressure behavior of a horizontal well and a vertical well both subject to edge water drive. Green and source function were used to evaluate the performance of horizontal well and vertical well, eventually, compared based dimensionless pressures and pressure derivatives computed by varying the reservoir geometry. Results presented as type curves show that the rate of decline of the pressure derivative curve is more sharper and sensitive in vertical well than horizontal well of the same geometry indicating a shorter period of clean oil production in vertical well than the horizontal well. The period of radial flow as shown by the horizontal flattened part of the type curve indicate that for all reservoir geometry, the horizontal well will be able to sustain longer period of the radial flow than vertical well given infinite conductivity condition.
There is increasing research on the adsorption of lead because its use in industrial processes has resulted in various forms of environmental contamination and negative human health issues. Currently, researchers have intensified their search for low-cost adsorbents like activated carbon produced from nonfossil sources. This study is focused on the use of Ethylene Di-Amine Tetra-Acetic Acid for the adsorption of Lead ions. It was conducted to optimize the process variables in the production of Palm Kernel Shell Activated Carbon modified with Ethylene Di-Amine Tetra-Acetic Acid. A 23 three-level Central Composite Design was used to develop a statistical model for the optimization of the time (10-130) X1, pH (5.0 – 7.0) X2, and adsorbent dose (0.4 -5.0g)X3. Data obtained from RSM on activated carbon production were subjected to ANOVA and analyzed using a second-order polynomial equation. The extent of lead ion removal by Ethylene Di-Amine Tetra-Acetic Acid activated carbon from aqueous solution was 96.30% at the solution pH of 7.2, contact time of 70 minutes, and an adsorbent dose of 2.1g/L. The Langmuir isotherm model was in good agreement with the experimental data.
Biomass-based activated carbon has received large attention due to its excellent characteristics such as inexpensiveness, good absorption behaviour, and potential to reduce strong dependence towards non-renewable precursors. The potential use of Palm Kernel Shell in modified activated carbon was evaluated by using the Response Surface Methodology. In this study, a 23 three-level Central Composite Design (CCD) was used to develop a statistical model for the optimization of process variables, contact time (10-130mins) X1, pH (5.0 – 8.0) X2, and adsorbent dose (0.4 -5.0g) X3. The investigation shows that Ethylene Di-Amine Tetra-Acetic Acid modified activated carbon prepared from Palm Kernel Shell is a promising adsorbent for the removal of copper ions from aqueous solutions over a wide range of concentrations with an optimized efficiency of 99% at the solution pH of 7.2, contact time of 70 minutes and adsorbent dose of 2.1g/L. The adsorption results are in line with the linear and quadratic model representation, which is evident from the models for optimization of copper ions.
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