Quality and Trends of Automotive Fuels

Automotive engines are designed to convert chemical energy to mechanical energy. The efficiency of this conversion is governed by thermodynamics. The two most common engines utilize gas oil and gasoline fuels for this purpose. However, the combustion processes are radically different. The combustion sequence and relative characteristics for both engine types will be discussed. Due to different combustion requirements, the fundamental properties of both fuels will also be examined as these are significantly different for the two fuel types. The main fuel properties discussed are energy density, stability, fluidity, corrosion, contaminants, safety, wear and environmental aspects. Also, with the advent of various renewable components in both fuels, new trends are emerging for both fuel quality assessments as these are molecularly distinct from their crude oil counterparts

Gasoline Lubricity

It is concluded that the lubricity of gasoline is the least well understood of all three fuels due largely to the lack of a reliable test method for measuring the lubricity of such a very volatile and contamination-sensitive material. To overcome this limitation, the development of a simple and easy methodology based on the general standard ASTM G-133 have been produced. This method is first used to investigate the lubricity of commercial gasolines to obtain some baseline data for further study. A comparison of the overall lubricity level of diesel fuel and gasoline fuel indicates that additive-free gasolines have significantly poorer lubricity than highly-refined, Swedish Class I diesel fuel, while commercial, detergent-containing gasolines range from slightly better to significantly poorer than a Swedish Class I diesel fuel. Especially LRP (lead replacement) gasolines developed a tests on refinery streams used to blend gasoline also show quite varied wear behaviour. Gasoline lubricity can be significantly improved by adding small amount of diesel lubricity additives. The results indicate that the type of fuel is a significant factor for discriminating the lubrication properties of each type of gasoline fuel and that lubricity is affected by bulk and trace composition characteristics of the fuel

Examination of lubricity of light and middle distillate fractions of oil (petroleum)

The objective of this doctoral thesis is the evaluation of the tribological properties of automotive gasoline and diesel fuel, as well as the improvement of the latter with the addition of bio-additives and biofuels. It is listed the physicochemical and tribological properties of automotive diesel fuels, heating diesel fuels and marine diesel fuels. What is typical for diesel fuel is the distinct separation between the values of the corrected wear diameter and the values of friction across the limit of 460 κm, which is noticeable difference in gradient of the linear dependence of the variance of these two values. There were samples of marine diesel that their lubricity was inappropriate and greater than the limit of 460 micrometers. It was examined the impact of biodiesel, vegetable oils and essential oils in the middle distillates fractions of oil. The methodology used to measure gasoline lubricity is the ASTM G133 standard test method for linearly reciprocating ball-on-flat sliding wear. Taking into account the experimental condition characteristics for the assessment of lubricity of refinery streams is noticed that they are characterized by worst anti-wear properties and lubricity in relation to diesel fuels. It was measured the gasoline lubricity of mixtures that emerged from the composition of the refinery streams and correspond to commercial gasolines. The increased wear scar diameter of the refinery streams contributes to larger diameter wear for the final commercial gasolines and therefore the value of the corrected wear scar diameter depends significantly from that of the constituent refinery streams. In particular, it is evident for all 36 mixtures, the wear mechanism taking place is that of the heavy adhesive wear and mild to heavy abrasive wear, and can coexist with that of the oxidative wear. The optimum addition rate is following the mixing rules that prevail in modern refineries and specifically an optimum rate of 35% for the stream of catalytic cracking FCC unit and 26% for the stream of catalytic reformer unit were observed. It was measured the lubricity of commercial gasolines. For sulfur content below 50 ppm and potassium content of less than 5 ppm was noticed increased wear and in particular greater than 700 κm for all commercial gasoline types. The chlorine content varies with an average of 10 ppm for commercial gasolines by potentiometric titration. The presence of chlorine is certified by elemental analysis performed by SEM

Utilization of iron oxide nanoparticles in drilling fluids improves fluid loss and formation damage characteristics

Summarization: well integrity. Rheological and fluid loss characteristics are key fluid properties that need to be optimized for the development of stable and “smart” water-based fluids. The objective of this research is to develop appropriate additives in order to reduce formation damage in drilling operations. We do this by examining the fluid loss characteristics for water-based muds, utilizing iron oxide nanoparticles as fluid loss additives. The nanoparticles benefit from their small size and it is anticipated to seal porous and/or fractured formations and thus are expected to provide a great potential for reduction of formation damage. We present API filtrate loss and filter cake characterization along with the changes in the rheological properties of drilling fluids containing various concentrations of nanoparticles. We have measured rheological properties with Couette type viscometer both at low and high temperatures. LPLT and HPHT API filter presses have been used for fluid loss measurements. Scanning Electron Microscope (SEM) pictures were used to analyze the nanoparticle size range and to reveal secrets of their good performance by providing deep insights for their microstructure, the interfacial phenomena and the interaction between bentonite particles and the nanoparticles. The examined nanoparticles have the potential not only to significantly reduce the fluid loss and develop a thin mudcake, but also to maintain optimal rheological properties thus providing effective pressure control. The required relatively low concentration in the drilling fluid provides a base for more efficient, environmental friendly and safer drilling practices.Παρουσιάστηκε στο: First EAGE Workshop on Well Injectivity and Productivity in Carbonate

Comprehensive assessment of additive and class G cement properties affecting rheology, fluid loss, setting time and long term characteristics of elastic cements

Summarization: Cement sheath integrity is very important in drilling and completion. Several additives are used to aid the process of preparing flowable cement slurry gaining sufficient strength over time. Sheaths need to be elastic and resilient and withstand several temperature and pressure cycles over the life of the well. Technology has made today available very sophisticated equipment. We present a comprehensive laboratory assessment of properties of various additives which formulate non-foamed elastic cements to determine optimal quantities and to associate them to short and long term cement properties, rheology, fluid loss, thickening time, compressive and tensile strength and elastic properties. We focus on the study of additives for producing elastic cements including effect of nanoparticles using XRD, XRF and SEM, Unconfined Compressive Strength, Cat-scanning, rheological and fluid loss measurements, NMR at P,T, for monitoring hydration kinetics and gel formation at downhole conditions. We monitor shear and compressional waves at P,T to estimate thickening time, compressive strength and static gel strength evolution. Thus we combine a multitude of measurements, to provide comprehensive assessment of the effect of additive properties on the mechanical properties of the elastic cements. Elastic cements are used in difficult environments where more cement elasticity is required to prevent casing debonding. We test efficacy of various additives on improving their properties. Protocols are presented on how one can utilize optimally the design and the implementation of different analysis to evaluate the effectiveness of additives on the mechanical properties of elastic cements. Additives have been developed to improve elastic properties of cements. Property measurements are routinely implemented in such materials. We correlate advanced NMR and Ultrasonic measurements in downhole conditions and integrate them with all other available laboratory measurements to provide means for determining optimal additive concentrations and to assess the use of nanoadditives on the properties of elastic cements.Παρουσιάστηκε στο: European Unconventional Conference and Exhibitio