Immiscible-Recycle Gas Injection to Enhance Recovery in an Iranian Naturally Fractured Reservoir: a Case Study with Emphasis on Uncertain Parameters

Utiskivanje recikliranog plina je proces iskorištavanja ležišta od kojeg se mnogo očekuje u proizvodnji nafte i plina. Metoda koristi kontinuirano utiskivanje rentabilnog obroka proizvedenog plina kako bi se održala energija ležišta i iskoristila viskozna sila kao pokretačka sila. Postoje brojne studije o utiskivanju recikliranog plina u konvencionalna ležišta, međutim postoje neki drugi čimbenici kao što su lokacija bušotina i vrsta završnog opremanja, obrok i tlak utiskivanja, koji jako djeluju na konačni rezultat ove metode, a većini njih nije uzimana u obzir. U ovoj studiji je proučen proces utiskivanja nemiscibilnog recikliranog plina u jedno od iranskih prirodno raspucanih karbonatnih ležišta na opsegu polja. Stvarni model heterogenosti je konstruiran i simuliran pomoću Eclipse-100 modula (softver za simulaciju ležišta). Ispitani su učinci radnih parametara, kao što su broj i lokacija injekcionih/proizvodnih bušotina, proizvodnih/injekcionih obroka, vrsta opremanja i perforirani produktivni interval a rezultat je uspoređen s metodom prirodnog iskorištavanja ležišta. Utvrđeno je da je, osjetljivost obzirom na broj bušotina, 1 injekcijska/2 proizvodne bušotine najučinkovitiji slučaj. Kapacitet proizvodnje od 500 m3/d (3 145 bbl/d) i tlak na dnu bušotine od 25 bara (362,6 psi), dali su veću proizvodnju nafte. Završno opremanje injekcionih bušotina u frakturi i proizvodnih bušotina u matriksu, ima bolju proizvodnost naftnog polja u odnosu na druge slučajeve. Štoviše, uočeno je da je najučinkovitija vrsta završnog opremanja injekcionih bušotina vertikalno, a za proizvodne bušotine horizontalno. Rezultati su pokazali da je moguće postići značajno sekundarno pridobivanje korištenjem optimalnih uvjeta za utiskivanje nemiscibilnog recikliranog plina u to ležište.Recycle-gas injection is a promising recovery process to produce oil and gas. The method uses continues injection of the produced gas at economical rates to keep the reservoirs energy up and using viscous force as the driving force. There are numerous studies done on recycle-gas injection in conventional reservoirs, however, there are some other factors such as location of wells and completion type, rate and pressure of injection which highly affect the final result of this method and failed to be considered in the majority of them. In this study, we investigate the immiscible recycle gas injection process in one of the Iranian carbonate naturally fractured reservoirs on a field scale. The real heterogeneous model was constructed and simulated by Eclipse-100 module. The effects of operational parameters, such as number and location of injection/production wells, production/injection rate, completion type and interval, on the immiscible gas injection performance were investigated and the result were compared with natural depletion method. It was found that, in sensitivity with number of the wells, 1 injection/2 production wells was the most efficient case. Also well oil production rate of 3 145 bbl/d (500 m3/d) and well bottom-hole pressure of 25 bar provided higher oil recovery. Completing of the injection wells in fracture and production wells in matrix has a better field oil efficiency in comparison to the other cases. Moreover, it was observed that the most efficient type of well completion for injection well is vertical and for production wells are horizontal. The results revealed that the substantial secondary oil recovery can be achieved using optimum conditions for immiscible recycle gas injection in this reservoir

Experimental investigation into l-Arg and l-Cys eco-friendly surfactants in enhanced oil recovery by considering IFT reduction and wettability alteration

Surfactant flooding is an important technique used to improve oil recovery from mature oil reservoirs due to minimizing the interfacial tension (IFT) between oil and water and/or altering the rock wettability toward water-wet using various surfactant agents including cationic, anionic, non-ionic, and amphoteric varieties. In this study, two amino-acid based surfactants, named lauroyl arginine (l-Arg) and lauroyl cysteine (l-Cys), were synthesized and used to reduce the IFT of oil–water systems and alter the wettability of carbonate rocks, thus improving oil recovery from oil-wet carbonate reservoirs. The synthesized surfactants were characterized using Fourier transform infrared spectroscopy and nuclear magnetic resonance analyses, and the critical micelle concentration (CMC) of surfactant solutions was determined using conductivity, pH, and turbidity techniques. Experimental results showed that the CMCs of l-Arg and l-Cys solutions were 2000 and 4500 ppm, respectively. It was found that using l-Arg and l-Cys solutions at their CMCs, the IFT and contact angle were reduced from 34.5 to 18.0 and 15.4 mN/m, and from 144° to 78° and 75°, respectively. Thus, the l-Arg and l-Cys solutions enabled approximately 11.9% and 8.9% additional recovery of OOIP (original oil in place). It was identified that both amino-acid surfactants can be used to improve oil recovery due to their desirable effects on the EOR mechanisms at their CMC ranges

Effect of environment-friendly non-ionic surfactant on interfacial tension reduction and wettability alteration; Implications for enhanced oil recovery

© 2020 by the authors. Licensee MDPI, Basel, Switzerland. Production from mature oil reservoirs can be optimized by using the surfactant flooding technique. This can be achieved by reducing oil and water interfacial tension (IFT) and modifying wettability to hydrophilic conditions. In this study, a novel green non-ionic surfactant (dodecanoyl-glucosamine surfactant) was synthesized and used to modify the wettability of carbonate reservoirs to hydrophilic conditions as well as to decrease the IFT of hydrophobic oil-water systems. The synthesized non-ionic surfactant was characterized by Fourier transform infrared spectroscopy (FTIR) and chemical shift nuclear magnetic resonance (HNMR) analyses. Further pH, turbidity, density, and conductivity were investigated to measure the critical micelle concentration (CMC) of surfactant solutions. The result shows that this surfactant alters wettability from 148.93° to 65.54° and IFT from 30 to 14 dynes/cm. Core-flooding results have shown that oil recovery was increased from 40% (by water flooding) to 59% (by surfactant flooding). In addition, it is identified that this novel non-ionic surfactant can be used in CO2 storage applications due to its ability to alter the hydrophobicity into hydrophilicity of the reservoir rocks

A New Approach to Simultaneously Enhancing Heavy Oil Recovery and Hindering Asphaltene Precipitation

A new chemical compound is developed at Petroleum University of Technology to enhance the recovery of the free imbibition process and simultaneously hinder asphaltene precipitation. The compound is tested on heavy oil samples from Marun oil field, Bangestan reservoir. The effects of the chemical compound on viscosity, hydrocarbon composition, and average molecular weight of the heavy oil are investigated. It is found that the substance dramatically reduces oil viscosity and molecular weight and hinders the precipitation of asphaltene in the heavy oil. The results of free imbibition tests demonstrate a significant recovery enhancement after oil reacts with the compound and is used in water in an Amott cell. Finally, the new chemical compound causes a significant reduction in surface tension and contact angle. This is verified by the molecular analysis of heavy oil after reacting with this ionic compound

A Numerical Study on Using Air Cooler Heat Exchanger for Low Grade Energy Recovery from Exhaust Flue Gas in Natural Gas Pressure Reduction Stations

Heat EXchangers (HEX) that are used in City Gate Station (CGS) systems are modeled numerically to recover the exhaust waste heat. It was tried to find the best viscous model to obtain results in accordance with experimental results and to change the heat exchanger design. This HEX is used for recovering heat from exhaust flue gas with a mixture of 40% water and 60% ethylene glycol as the cooling fluid. Then, the effects of sizes and numbers of fins and tube rows on recovered heat rate were investigated under various pump speeds. As the first step in solving the problem, SST k–ω and RNG k–ε suitable viscous models were chosen for these kinds of problems. Secondly, a new HEX is designed at a fixed coolant speed, pipe and fin thickness, and shell dimension because of operational constraints. Finally, the best HEX with the minimum pressure drop (minimum fin number) is numerically analyzed, and the new HEX specifications were extracted

Traumatic Dental Injuries of Permanent Anterior Teeth in Children referred to Dental School of Tehran University of Medical Sciences: A Retrospective Study: Traumatic Dental Injuries

Objectives Children frequently encounter dental problems related to traumatic dental injuries (TDIs). This study aimed to investigate TDIs among children aged 7-13 years, who were admitted to the Tehran School of Dentistry in Tehran, Iran. Methods This retrospective study was performed on 70 patients with 129 TDIs. Information, such as age at the time of the accident, gender, cause and type of TDI, the interval between the accident and the emergency care, and treatment, was gathered from the patients’ records. During the follow-up session, the pulp sensibility, probing, and percussion tests were conducted. The collected data was statistically analyzed using Fisher’s exact test and Chi-square test. The significance level was set at P<0.05. Results A total of 129 TDIs were reported during 2018-2021. Maxillary central incisors (80.62%) were the most commonly involved teeth, followed by maxillary lateral incisors (17.82%) and mandibular lateral incisors (1.55%). Falls were the main contributor to TDIs (31.78%). The most frequent TDIs involved enamel-dentin fractures without pulp involvement (37.20%) and subluxation (19.37%), followed by enamel-dentin fractures exposing the pulp (10.85%), avulsion (10.85%), infraction (4.65%), lateral luxation (3.87%), intrusion (3.87%), and extrusion (3.10%). Splinting (26.61%) and restoration (23.74%) were the most frequent treatments. The average follow-up period was 2-3 years, with a survival rate of 67%. Conclusion It appears that a significant number of parents are unaware of the necessity of immediate treatment and regular follow-up after TDIs, which can result in a high rate of treatment failure.

Using Continuous Wavelet Transform and Short Time Fourier Transform as Spectral Decomposition Methods to Detect of Stratigraphic Channel in One of the Iranian South-West Oil Fields

Classical seismic methods for characterization of hydrocarbon reservoirs have been used for decades. Stratigraphic events affect seismic sections in addition to structural events. Today the necessity of usage of seismic sections to determine reservoir extension and stratigraphic characteristics is increasing. Conventional seismic sections cannot display most of the important events in reservoir studies. The study of frequency content of seismic sections can provide better understanding to geoscientists, as well as interpreters in the field of petroleum engineering studies. An isofrequency process is a powerful tool in terms of reservoir imaging. One of the methods that provides isofrequency slice is Spectral Decomposition (SD). SD is a comprehensive method that eliminates most of limitations encountered in seismic data to reveal geological information. SD provides continuous analysis of amplitude, frequency, phase, and energy spectrum. Therefore, SD is applied to obtain an amplitude spectrum of frequency content of seismic trace which is attributed to the temporal center of the sample trace, so higher frequency resolution is obtained at lower frequencies and higher time resolution at higher frequencies. In this paper, Short Time Fourier Transform (STFT) and Continuous Wavelet Transform (CWT) as SD methods were used in order to detect stratigraphic channel at one of the Iranian South-West oil fields for which it has the potential to be considered as a reservoir

Prediction of Nitrogen Injection Performance in Conventional Reservoirs Using the Correlation Developed by the Incorporation of Experimental Design Techniques and Reservoir Simulation

Enhanced oil recovery using nitrogen injection is a commonly applied method for pressure maintenance in conventional reservoirs. Numerical simulations can be practiced for the prediction of a reservoir performance in the course of injection process; however, a detailed simulation might take up enormous computer processing time. In such cases, a simple statistical model may be a good approach to the preliminary prediction of the process without any application of numerical simulation. In the current work, seven rock/fluid reservoir properties are considered as screening parameters and those parameters having the most considerable effect on the process are determined using the combination of experimental design techniques and reservoir simulations. Therefore, the statistical significance of the main effects and interactions of screening parameters are analyzed utilizing statistical inference approaches. Finally, the influential parameters are employed to create a simple statistical model which allows the preliminary prediction of nitrogen injection in terms of a recovery factor without resorting to numerical simulations

Identifying Flow Units Using an Artificial Neural Network Approach Optimized by the Imperialist Competitive Algorithm

The spatial distribution of petrophysical properties within the reservoirs is one of the most important factors in reservoir characterization. Flow units are the continuous body over a specific reservoir volume within which the geological and petrophysical properties are the same. Accordingly, an accurate prediction of flow units is a major task to achieve a reliable petrophysical description of a reservoir. The aim of this paper was core flow unit determination by using a new intelligent method. Flow units were determined and clustered at specific depths of reservoir by using a combination of artificial neural network (ANN) and a metaheuristic optimization algorithm method. At first, artificial neural network (ANN) was used to determine flow units from well log data. Then, imperialist competitive algorithm (ICA) was employed to obtain the optimal contribution of ANN for a better flow unit prediction and clustering. Available routine core and well log data from a well in one of the Iranian oil fields were used for this determination. The data preprocessing was applied for data normalization and data filtering before these approaches. The results showed that imperialist competitive algorithm (ICA), as a useful optimization method for reservoir characterization, had a better performance in flow zone index (FZI) clustering compared with the conventional K-means clustering method. The results also showed that ICA optimized the artificial neural network (ANN) and improved the disadvantages of gradient-based back propagation algorithm for a better flow unit determination