Experimental investigation of immiscible water-alternating-gas injection in ultra-high water-cut stage reservoir

Water-alternating-gas (WAG) injection is recommended as a means of improving gas mobility control. This paper describes a series of coreflood tests conducted to investigate the potential for continuous gas injection and WAG injection in ultra-high water-cut saline reservoirs. The mechanisms of immiscible water-alternating-nitrogen injection on residual oil distribution are analyzed, and pore-scale analysis is conducted. The effect of injection parameters on residual oil distribution and recovery efficiency is also evaluated. Coreflood results show that tertiary oil recovery efficiency is significantly higher using WAG injection than continuous gas injection during the ultra-high water-cut period. Pore-scale visualization illustrates the movement of gas through the waterflooded channels into the pore space previously occupied by water and residual oil, which then becomes trapped. Injected gas breaks the force balance of microscopic residual oil and reduces residual oil saturation. This mobilizes the displaced/collected residual oil into large waterfilled pores and blocks several water channels. WAG flooding can decrease free-gas saturation and increase trapped-gas saturation significantly, resulting in decreased relative permeabilities of gas and water. The experimental results indicate that appropriate WAG design parameters could enhance recovery by 15.62% when the injected pore volume of water and gas in the cycle is 0.3 PV at a gas/water injection ratio of 2:1. The results from this study will allow researchers and reservoir engineers to understand and implement immiscible WAG injection as an enhanced oil recovery method in ultra-high water-cut stage reservoirs.Cited as: Kong, D., Gao, Y., Sarma, H., Li, Y., Guo, H., Zhu, W. Experimental investigation of immiscible water-alternating-gas injection in ultra-high water-cut stage reservoir. Advances in Geo-Energy Research, 2021, 5(2): 139-152, doi: 10.46690/ager.2021.02.0

Green extraction and in vitro anti-mycobacterial activity of Hydrocotyle sibthorpioides Lam. and Carica papaya L. leaves collected from Assam, India

60-66The traditional healers of different parts of India use goat urine for the treatment of tuberculosis. On the basis of ethnomedicinal claims, two plant species namely Hydrocotyle sibthorpioides and Carica papaya were extracted with raw (fresh) and photo-activated goat urine as a menstruum. The present study reports the in vitro antimycobacterial activity of the leaf extracts of H. sibthorpioides and C. papaya against Mycobacterium smegmatis (ATCC 700084 /Mc2155 strain). It was observed that the photo-activated goat urine and raw goat urine leaf extracts could inhibit M. smegmatis. Among all the four extracts, the extract of C. papaya using photo-activated goat urine showed the highest antimycobacterial activity against M. smegmatis

Green extraction and in vitro anti-mycobacterial activity of Hydrocotyle sibthorpioides Lam. and Carica papaya L. leaves collected from Assam, India

The traditional healers of different parts of India use goat urine for the treatment of tuberculosis. On the basis of ethnomedicinal claims, two plant species namely Hydrocotyle sibthorpioides and Carica papaya were extracted with raw (fresh) and photo-activated goat urine as a menstruum. The present study reports the in vitro antimycobacterial activity of the leaf extracts of H. sibthorpioides and C. papaya against Mycobacterium smegmatis (ATCC 700084 /Mc2155 strain). It was observed that the photo-activated goat urine and raw goat urine leaf extracts could inhibit M. smegmatis. Among all the four extracts, the extract of C. papaya using photo-activated goat urine showed the highest antimycobacterial activity against M. smegmatis

An Experimental study of instability and viscous fingering in porous medium

Bibliography: p. 90-102.Low recovery and inefficient sweep due to premature breakthrough of the displacing fluid at the producing well during displacement - miscible or immiscible, have long been recognized as the major problem areas for any enhanced oil recovery project involving fluid-fluid displacement techniques. This study presents an experimental investigation of the phenomena of instability and viscous fingering in fluid-fluid displacements in a porous medium as a function of viscosity ratio between the displaced and displacing fluids displacement rates at which the displacing fluid is being injected to the porous medium and interfacial tension between the displaced and displacing fluids. Studies have been carried out both for miscible and immiscible displacements in imbibition and drainage directions. Also studied was the miscible displacement of the non-wetting phase in the presence of high wetting phase saturation. Interpretation of the experimental findings in terms of the linear stability theory are presented. Photographic details of a representative set of runs are also presented to highlight the qualitative aspects exhibited by the fingers under different experimental conditions

Fixed Dose Oral Dispersible Tablet of Bitter Drug Using Okra Mucilage: Formulation and Evaluation

Background: The solid oral dosage forms containing bitter drugs need improved palatability for administration. Formulation scientists have given attention to the improvement of taste masking technologies and utilised various strategies. Objective: The present work aimed to mask the bitter taste of Promethazine Hydrochloride by formulating Oral Dispersible Tablets using Okra mucilage as a taste-masking agent.  Methods: The Okra mucilage was extracted from Okra by the aqueous extraction process. An emulsion solvent diffusion technique was used for masking the bitter taste of Promethazine Hydrochloride by using Okra mucilage. The Oral Dispersible Tablet was prepared by the wet granulation method. The mucilage and the formulation were characterized and evaluated by standard methods and protocols. Results: Taste masking of the bitter drug was successfully achieved by Okra mucilage. The DSC and FTIR study revealed that the drug molecule was compatible with okra mucilage and drug entrapment efficacy was found to be 94.76%. The palatability test asserted that masking of the bitter taste of the drug.  The In vitro drug release study showed that the F7 tablet batch has a better drug release rate and followed non- fickian mechanism of drug release. Conclusion: Thus, taste masking with Okra mucilage was successful and this opens opportunities for application of common edible substances in formulation development. Keywords: Fast disintegrating tablet; Natural polymer; Mouth dissolving tablet; Promethazine Hydrochloride; Taste maskin

Can Effects of Temperature on Two-Phase Gas/Oil-Relative Permeabilities in Porous Media Be Ignored? A Critical Analysis

Thermal recovery processes for heavy oil exploitation involve three-phase flow at elevated temperatures. The mathematical modeling of such processes necessitates the account of changes in the rock–fluid system’s flow behavior as the temperature rises. To this end, numerous studies on effects of the temperature on relative permeabilities have been reported in the literature. Compared to studies on the temperature effects on oil/water-relative permeabilities, studies (and hence, data) on gas/oil-relative permeabilities are limited. However, the role of temperature on both gas/oil and oil/water-relative permeabilities has been a topic of much discussion, contradiction and debate. The jury is still out, without a consensus, with several contradictory hypotheses, even for the limited number of studies on gas/oil-relative permeabilities. This study presents a critical analysis of studies on gas/oil-relative permeabilities as reported in the literature, and puts forward an undeniable argument that the temperature does indeed impact gas/oil-relative permeabilities and the other fluid–fluid properties contributing to flow in the reservoir, particularly in a thermal recovery process. It further concludes that such thermal effects on relative permeabilities must be accounted for, properly and adequately, in reservoir simulation studies using numerical models. The paper presents a review of most cited studies since the 1940s and identifies the possible primary causes that contribute to contradictory results among them, such as differences in experimental methodologies, experimental difficulties in flow data acquisition, impact of flow instabilities during flooding, and the differences in the specific impact of temperature on different rock–fluid systems. We first examined the experimental techniques used in measurements of oil/gas-relative permeabilities and identified the challenges involved in obtaining reliable results. Then, the effect of temperature on other rock–fluid properties that may affect the relative permeability was examined. Finally, we assessed the effect of temperature on parameters that characterized the two-phase oil/gas-relative permeability data, including the irreducible water saturation, residual oil saturation and critical gas saturation. Through this critical review of the existing literature on the effect of temperature on gas/oil-relative permeabilities, we conclude that it is an important area that suffers profoundly from a lack of a comprehensive understanding of the degree and extent of how the temperature affects relative permeabilities in thermal recovery processes, and therefore, it is an area that needs further focused research to address various contradictory hypotheses and to describe the flow in the reservoir more reliably

Brine-Dependent Recovery Processes in Carbonate and Sandstone Petroleum Reservoirs: Review of Laboratory-Field Studies, Interfacial Mechanisms and Modeling Attempts

Brine-dependent recovery, which involves injected water ionic composition and strength, has seen much global research efforts in the past two decades because of its benefits over other oil recovery methods. Several studies, ranging from lab coreflood experiments to field trials, indicate the potential of recovering additional oil in sandstone and carbonate reservoirs. Sandstone and carbonate rocks are composed of completely different minerals, with varying degree of complexity and heterogeneity, but wettability alteration has been widely considered as the consequence rather than the cause of brine-dependent recovery. However, the probable cause appears to be as a result of the combination of several proposed mechanisms that relate the wettability changes to the improved recovery. This paper provides a comprehensive review on laboratory and field observations, descriptions of underlying mechanisms and their validity, the complexity of the oil-brine-rock interactions, modeling works, and comparison between sandstone and carbonate rocks. The improvement in oil recovery varies depending on brine content (connate and injected), rock mineralogy, oil type and structure, and temperature. The brine ionic strength and composition modification are the two major frontlines that have been well-exploited, while further areas of investigation are highlighted to speed up the interpretation and prediction of the process efficiency