M. R. Islam

A Review of Separation of Gases Using Membrane Systems

Abstract Gas flaring has been an option used by the petroleum industry for many decades. With increasing awareness of its environmental impact and the ratification of the Kyoto protocol by most of the member countries, it is expected that the process will be discouraged for the near future. It will require significant changes in the current practices of oil and gas production and even though advances are being made in separation technologies of liquids and gases, immediate solutions are required in case of the latter. This article investigates the current options of gas separation and outlines the future trends in the subject. In separation of gases, membranes offer the greatest potential. In interaction with a membrane, a high degree of permeability coupled with a large selectivity of a specific gaseous species ensures superior performances in the gas processing industry. Economically, the advantage of membrane separation technology is immense. The separation of natural gas by thin barriers termed as membranes is a dynamic and rapidly growing field, and it has been proven to be technically and economically superior to other emerging technologies. This superiority is due to certain advantages which membrane technology benefits from, including low capital investment, low weight, and space requirement and high process flexibility. In the past ten years, the membrane gas separation technology has advanced greatly and can now be regarded as a competitive industrial gas separation method. The benefits of “Membrane Technology” also include higher recovery of the desired gaseous effluent that can be reused for multiple purposes. This article discusses various experimental and analytical models related to current and future membrane technologies that include regular, liquid and hybrid systems. Economically attractive options that are also environmentally appealing are discussed. Finally, research topics that need to be undertaken in order to establish no-flare designs in the future are presented.

A COMPREHENSIVE APPROACH FOR MODELING SORPTION OF LEAD AND COBALT IONS THROUGH FISH SCALES AS AN ADSORBENT

ABSTRACT Removal of lead and cobalt cations from both industrial and municipal water is of extreme importance for waste water disposal standards. Using fish scales as an adsorbent, 95% of the lead cations and 70% of the cobalt ions can be removed. The processes related to the removal of the cations include adsorption and precipitation. The effect of precipitation of the cations in a neutral medium (pH 7) is studied and is found to be insignificant. Although the effect of precipitation is negligible in the studied experimental runs, it may assume significance in a highly nonporous medium. As sorption dictates the interactions between the bulk and adsorbed phases, it is the most important factor influencing the transport of the chemical species through the medium. Mobility of the cations has extreme importance to overall sorption characteristics because of high adsorption coefficients of the fish scales. It can be further concluded that even at cation concentration levels of 1000 ppm, sorption behavior is insensitive to change. To investigate the nature of the sorption mechanism, a series of experimental runs was conducted using fish scales of the Gadus Morhua (Atlantic cod) and Lethrinus nebulosus (spangled emperor or shouairi) species as substrates. A simulation model based on the theory of surface excess with mechanical entrapment is developed in this study. Numerical simulation results demonstrate reasonable agreements with the experimental results. This study illustrates that variations of flow rates of the cations did have a considerable effect on breakthrough time intervals. An increase in flow rate led to earlier contaminant breakthrough. However, variance of the cation concentrations did not have a dominant effect on the corresponding breakthrough values. The effect of porosity of the adsorbents is observed, and it is determined it has a profound impact on adsorption phenomena. The dispersion parameter is found to be a function of porosity, and its effect was studied in relation to the flow rate of the bulk phase. A decrease in porosity of the adsorbent results in an increase of the retardation factor of the contaminant in bulk phase and an equivalent delay in the breakthrough interval. In order to study the adsorption characteristics by surface excess model, the pH parameter was maintained at a constant pH value of 7 for all the experimental runs. The adsorption coefficient (K) was coupled into the numerical model as a parameter independent of the pH values. The numerical simulations did fit reasonably well with the experimental data. The surface excess theory has been tested in the past only for anionic solutions. The significance of this research is that this model has been applied for the first time with respect to a bio-adsorbent in relation to heavy metal cations. It is found to be suitable for describing adsorption behavior of metallic contaminants at neutral pH. For studying adsorption with respect to the pH variable, a different adsorption model based on, the Langmuir isotherm is proposed.

Detection of Precipitation in Pipelines

Abstract One of the major unsolved complex problems confronting the petroleum and chemical industries at present is the untimely deposition of heavy organic and other solids dissolved or suspended in the fluid flow systems. The production, transportation, and processing of petroleum can be significantly affected by flocculation and deposition of such compounds in the course of industrial processing systems, including transfer conduits, reactors, and refineries and upgrading equipment, with devastating economic consequences. Heavy organics such as paraffin, wax, resin, asphaltene, diamondoid, mercaptdans, and organometallic compounds can precipitate out of the crude oil solution due to various forces causing blockage in the oil reservoir, well, pipeline, and in the oil production and processing facilities. It is important to producers that the potential organic deposition can be predicted so that the production strategy can be designed to prevent, if possible, or mitigate this problem. Cleaning the pipeline has a common commercial term, pigging. Early detection of precipitation can reduce pigging and, in turn, the maintenance cost considerably. Prediction of why and when precipitations occur has gained much interest in recent years. Most studies focus on the chemical behavior of the crude oil and its contamination. A nonintrusive instrumentation technique for on-line inspection that can yield as much detailed information about the interior of the pipe as possible is highly desirable. In this article, the detection of asphaltene and paraffin wax is studied using various techniques. The techniques include the use of solid detection system by light transmittance measurement for asphaltene detection, the use of photodiode for light transmittance measurement for liquid wax, the use of ultrasound and strain gauge for detecting solid wax.

Numerical Investigation of the Prospects of High Energy Laser in Drilling Oil and Gas Wells

Abstract Lasers are expected to provide a less expensive alternative to conventional machining and have found wide spread use in many industries. However, the physical phenomena involved in many laser applications are not fully understood. A better and more quantitative understanding of the physical mechanisms governing these phenomena will diminish the need for extensive trial and error experiments. Most of the theoretical models available in the literature have dealt with quasi-steady material removal using a continuous wave laser. This article presents a numerical model to predict the transient thermal behavior process of rocks under the influence of a pulsed laser. A wide range of parameters were considered in this study, the laser powers were varied from 0.1 to 100 kW and the lasing time was varied between 1 and 100 s. One of the results presented in this article shows that limestones consume less energy per unit volume of material removed as compared to sandstones. A comparison between the findings of this numerical study and published experimental data is also presented and shows a qualitative agreement. Finally, it is shown that numerical modeling can be useful in scaling up laboratory results to field applications.

Lasing into the Future: Potentials of Laser Drilling in the Petroleum Industry

Abstract The need for a new method of drilling oil and gas wells is immense. Current drilling techniques used were developed at the beginning of the last century. Many problems persist with this method including downtime due to dull bits, the lack of precise vertical or horizontal wells and formation fluid leakage during drilling due to the lack of a seal around the hole. Laser drilling is a new technology that has been proposed as a method to eliminate the current problems while drilling. Although experiments for laser drilling were conducted in the 1960s and 1970s, it is only recently that this research area has been redirected to the oil and gas industry. This article reviews the benefits of laser drilling, current laser types, and the experimental work that has been conducted. The experimental work conducted thus far is performed with several different lasers such as the US Armys MIRACL and the US Navys COIL. The data that was generated by these studies was executed on several types of cores including sandstone, limestone, and shale. The effect that lasing has on porosity and permeability as well as the effect of saturation and pressure on lasing was determined. The work conducted shows that a great future potential awaits the oil and gas industry with laser drilling.

A New Technique for Cleaning Horizontal Wellbores

Abstract The plugging of horizontal wellbores can lead to significant loss of productivity and can nullify the benefit of a horizontal wellbore, which is expensive to create. Cleaning horizontal wellbores is a formidable challenge. The problem is particularly complex for heavy oil formations that show asphaltene, sand, and other difficult-to-remediate problems. This paper aims at developing a new technique that can effectively clean up a horizontal wellbore without requiring expensive workovers. The technique involves the use of ultrasonic treatment coupled with foam treatment. Initial experiments show that ultrasonic treatment can reduce plugging in two ways—the first is the reduction in oil viscosity (especially in the presence of asphaltic crudes) and the second is the ability of ultrasound to keep particles in suspension. The second effect can be due to the generation of microbubbles. The process is coupled with in situ generation foam. In order to generate foam, a particular type of surfactant is chosen from a selection of a wide range of surfactants supplied by the service companies. While the design of the device that couples both these effects needs to be optimized, an initial series of experiments shows good promises.

Laser Based Detection of Paraffin in Crude Oil Samples: Numerical and Experimental Study

Abstract A laser spectroscope was used to detect paraffin in paraffin contaminated oil samples. After passing through the oil sample, the laser light was detected by using a semi-conductor photodiode, which in turn converts the light signal into electric voltage. The samples studied have paraffin concentrations ranging from 20–60% wt and a thickness of 1–10 mm. The results showed a good agreement with Beer Lamberts Law for the attenuation of light. A 1-D mathematical model based on energy balance and describing the process of laser radiation attenuation within the oil sample was developed and numerically solved. The model was used to predict the net laser light and the amount of light absorbed per unit volume at any point within the oil sample. The results of the numerical model were found to be in correlation with those obtained from the experiments. The mathematical model presented was then used for different types of oil products to determine the local rate of absorption in an oil layer under different working conditions. Most of the factors affecting the light absorption were considered. The effects of the angle of incidence, bottom reflectivity, and layer depth are presented and discussed.

Estimation of the Substrate Concentration Profiles in Petroleum Pipelines Containing Biofilms

Abstract In industrial systems, the formation of biofilms can cause many problems, such as an increase in the flow resistance of pipelines, energy losses in fluid transport and heat exchangers, product contamination, materials deterioration, and biocorrosion. As a result, biofilms contribute substantially to economic losses in the industry. Corrosion is particularly an issue in the petroleum industry and its implications range from down-hole completion through petroleum processing units. Much of this corrosion is attributed to microbial activities. This paper proposes a mathematical model for predicting substrate concentration for such microbial growth. Substrate concentrations in the system and near the biofilm surface are one of the parameters that has a great effect in determining the extent of the problems associated with biofilms. In this study, a convective-diffusion model under various flow conditions (stagnant, laminar, and turbulent) has been solved using the finite difference technique, employing the alternating direction implicit (ADI) method. The model assumes that a liquid containing substrate and bacteria is flowing in a pipeline with known concentrations at the inlet and then predicts the variation of the transient (as a function of time) substrate concentration along the pipeline and as a function of the pipe radius. The model is then used to predict and estimate the substrate concentration profiles on the biofilm surface under different environmental conditions. A parametric study was also conducted to study the effect of the different parameters influencing the substrate concentration profiles in the system and on the biofilm surface.