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 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 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 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.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.