Ezio MESINI's scientific work is documented by 10 printed books and over 200 papers, many of which are published in the best international magazines or presented at international congresses. This activity focused: at first (years '80 and '90) on the classical topics of Hydrocarbons and Subsoil Fluids; sussequently (years '10 and '20), on topics related to theinteraction energy-environment orienting studies to the safety of industrial operations and environmental protection.
PART 1: Years 80s and 90s - studies were addressed in particular that involved:
- Subsidence phenomena due to underground fluid withdrawals. Subsidence problems due to underground fluid withdrawal have been long recorded all over the world, causing heavy effect on the environment. In Italy, numerous cases have been recognized, in the areas of Po Delta and the cities of Venice, Ravenna and Bologna. Many studies are under development to further investigate the influence of gas production on subsidence, coastal regression and upsetting of the hydraulic system. Attention is paid to the studies on the application of new tools and modeling techniques to measure and predict reservoir compaction. The purpose of this research is at first to report the very well known subsidence case histories of the towns of Ravenna and Bologna. Finally, the research discusses the measurement of mechanical properties of Northern Italy clastic formations. In particular the research reports both the laboratory measurements and the in-situ investigations of formation compaction by means of extensometers and radioactive markers. In addition, it has also been attempted an approach to estimate the precision and accuracy of the above techniques, and the perturbation effects induced by in-situ monitoring systems.
- Modelling of hydrocarbon reservoirs. Numerical models are developed for a two-dimensional, two-phase immiscible flow model. The model is based on the Galerkin procedure and refers to an incompressible system. Capillary pressure and gravity effects are considered. Spatial discretization is obtained by linear-triangular finite elements, by which the terms of elemental matrices are expressed in analytical form, whereas a Crank-Nicolson finite-difference scheme is used for the step-by-step integration in time. A simultaneous-solution technique is used to solve for potentials and saturations. A high1yefficient Gauss elimination algorithm is used to solve the set of linear algebraic equations which results from the Galerkin method. The programs may be used to simulate displacement processes between two immiscible fluids into porous media, particular1y to simulate water injection, for two-dimensional areal and sectional geometries or axis-symmetric geometry. From their use, indications of a strategic nature can be drawn for the purposes of the exploitation of hydrocarbon fields, as regards not only a primary recovery, but also and above all in the modern perspective of an "improved" exploitation (Improved Oil Recovery) of the field. In particular, in the context of projects aimed at exploitation through water injection techniques (waterflooding), given the importance of the chemical compatibility between injection and layer water, models capable of evaluate any variations in the permeability of the affected layers.
- Problems connected to drilling. On this issue, suitable drilling techniques have been proposed for the exploitation of natural gas resources in the upper Bolognese Apennines. The modest, albeit frequent, mineralizations in question are characterized by the difficulty of their identification and the simplicity of the drilling and production methods currently in use. We then tried to highlight those aspects related to the recurrent use of hydrocarbon drilling techniques that could be suitably adapted to the case of geotechnical and hydrogeological investigations. Subsequently, the advantages, disadvantages, potentialities and limitations of mechanical coring and recording techniques of the drilling parameters were analyzed, in order to optimize the drilling operations in economic terms. Furthermore, in order to have a sufficiently representative picture of information of a geotechnical-hydrogeological nature, a database has been set up which allows information to be systematically collected and returned graphically. From this study, which refers to the Bolognese high plain, information can be drawn that affects not only the georesources, but also the territory in general. The technical performance of both tricone chisels with extended nozzles and monobloc chisels with PDC (Polycrystalline Diamond Compact) synthetic diamond inserts were also taken into consideration. In particular, the characteristics and operating principles of the PDC bits were illustrated, highlighting on the one hand the advantages and disadvantages of their application in the field of drilling for hydrocarbon exploration, and on the other the technological developments relating to new types of materials and structural modifications. Other studies have analyzed the wear patterns of tricone bits used for drilling a geothermal reservoir, in order to define the mechanisms that lead to premature wear, with a consequent increase in the perforated cost-meter. In particular, it was found that the particular conditions of the hole, the high temperature of the formation and the type of bearing used interact with each other, causing drastic reductions in the drilling economy. Further researches experimentally investigated the inhibiting effect on clays induced by water-based drilling fluids with the addition of glycols and potassium ions. The results of the investigations allow us to state that the fluids thus packaged are characterized by inhibition values close to those shown by oil-based sludge, but have, compared to the latter, a low degree of toxicity, compatible with current regulations. Finally, the combined Geosteering measurement systems that have recently seen extensive development in the oil field were critically examined. These systems consist of equipment used in directional drilling which, together with the possibility of guiding the trajectory of the hole in real time, detect measurements at chisel height, allowing to drill directional wells not on the basis of the geometric project trajectory, but following the objective mining on the basis of geological and lithological data acquired in real time.
- Laboratory investigations on porous media: core analysis. Reservoir rocks belong to the large category of porous materials, which are an object of study in various scientific and technological fields, from engineering to geology, the biomedical disciplines, the food and ceramics industries, etc. Within these fields, particular importance is devoted to the study of natural porous media forming various types of soils, consolidated formations and cemented rocks, which potentially contain hydrocarbon reservoirs. The specific focus of this chapter is limited to those geological and engineering disciplines related to the study of reservoir rocks. In nature, hydrocarbons are located and may move inside the porous spaces of the permeable rocks forming the reservoir. Generally speaking, the petrophysical characteristics of a reservoir rock describe the properties of natural porous media in terms of their ability to contain fluids, their mobility, and their arrangement within the rock matrix. The petrophysical properties of porous media determine the volume of fluids contained in the reservoir, and the quantity and ease with which they can flow towards production wells. In particular, as far as hydrocarbon reservoirs are concerned, the percentage of oil and/or gas contained within a unit volume of reservoir rock is equal to the product of the rock's porosity and its saturation. To calculate the volume of hydrocarbon reserves, alongside porosity and fluid saturation (correlated, among other things, with the capillary properties of the reservoir rock), both the volume of the hydrocarbon formation and the thermodynamic properties of the hydrocarbon mixture must be identified. On the other hand, to evaluate the production capacity of a reservoir requires information on the ability of the fluids to move through the porous medium, a property known as permeability. Other experimental and theoretical studies were addressed to the definition and measurement of the Non-Darcy flow regime within natural and artificial porous media, with particular reference to applications in the field of natural gas production
- Measurements, controls and production in hydrocarbons reservoirs. The methods of use of the dipmeter were highlighted, illustrating the recent evolutions of this instrument, created to measure the direction (azimuth) and immersion (slope) of the formations crossed by the drilling. In particular, the principles of operation and use of the dipmeter were described and emphasis was placed on the processing phase of the data collected in the well, in order to obtain the interpretation of the slopes and azimuths of the recorded events. Further research has dealt with the problems related to the operating procedures that allow to reach, through the manual interpretation of a set of logs, the information necessary both for the recognition of the intervals on which to carry out the production tests, and for the knowledge of the fundamental parameters for the 'reservoir engineer for the purpose of calculating reserves. In particular, the log set considered includes electrical resistivity, sonic and radioactive measurements recorded in an offshore well in the middle Adriatic. Again on this subject, a volume was also published in which the theoretical and applicative aspects relating to the logs recorded in the well were analyzed. The volume was designed to be of a formative nature and at the same time of technical-scientific study for students, for lovers of earth sciences and for georesource technicians. Still on the subject of well measurements, a practical method has been proposed for the evaluation of the elastic anisotropy of the subsoil through the elaboration of vertical seismic profiles in the well (VSP Walkaway). The results obtained show that the introduction of anisotropy factors leads to a significant improvement in the definition of the image, especially in areas located at a certain distance from the well, while in areas close to the well itself, the use of these factors does not lead to any improvement. The combined measurement systems, called Logging While Drilling (LWD), which have recently seen extensive development in the oil field, were also critically illustrated. The LWD systems allow the real-time acquisition of measurements of inclination, direction, temperature and diameter of the hole, the survey of petrophysical parameters through log of resistivity, density, gamma and radioactive rays, the evaluation of drilling parameters (weight, revolutions , torsion, vibrations and impacts). Studies aimed at the field of production have addressed the problems related to the crystallization and deposition of paraffins in the reservoir and along the pipelines. In particular, the technical interventions aimed at inhibiting the precipitation of paraffin compounds, and at coping with their eventual removal, were examined. The inhibition interventions can be divided into thermal methods, basically based on maintaining the temperature of the crude oil above the Cloud Point, and chemical methods, based on the modification of the phase behavior of the crude. As part of the problems relating to polyphasic motion in horizontal pipelines, experimental values of the compressibility coefficient of concentrated water-coal mixtures were obtained. For this purpose, an experimental laboratory apparatus was specially developed, the calibration of which was carried out by comparison with values of the water compressibility coefficient, taken from the literature. Furthermore, methodologies have been identified for the characterization of water-carbon-additive mixtures, through the analysis of the magnetic relaxation of the hydrogen core under resonance conditions, in order to improve the basic knowledge of the system, and to define with better precision practical procedures for product quality control.
PART 2: Years 10s and 20s - Shortly, the studies were addressed in particular to the analysis of:
• carbon capture and storage techniques produced by industrial plants (CCS, Carbon Capture and Storage). Evaluation of the potential for storage in deep saline aquifers of the Lombardy Region and development of a preliminary numerical model for the hydrodynamic study of the subsoil.
• environmental and regulatory issues (health and safety of workers and environmental protection) arising from hydrocarbon exploration activities, with particular reference to crude oil and natural gas fields onshore and offshore.
• contemporary ethical reflection (man-nature relationship, application logic for the protection of the biosphere and rights of future generations, historical-cultural roots of environmental disasters, etc.); Analysis of some aspects more closely related to project approaches, research and study of prevention logic.
In addition, since the beginning of his research activity, Ezio Mesini continues to show interest in studies concerning history of science and technique with particular reference to:
- certain aspects of Earth Sciences and Engineering from the 16th century - giving light to the fundamental work of Giorgio Agricola (1494-1555) - illustrating the importance of the corpus of geological, mining and metallurgical works in the history of technology;
- the history of oil, where it has conducted studies to highlight oil and gas documentation of the pre-industrial period and to illustrate the first studies that paved the way for the modern oil industry;
- over 90 Conferences organized since 2005 at the Faculty/School of Engineering; conferences born from the observation that the historical dimension of the scientific and technical teachings of the Engineering faculties is an integral part of the evolution of our civilization and that the historical dimension should be accompanied by elements of a philosophical and epistemological type which necessarily combine with technical and scientific knowledge. However, in today's societies it is very easy to see schematisms that divide the two cultures and that create false borders where unity should instead be identified. The history of science and technology, the history of the company are so many schemes that attempt to open up new research fronts, alongside the "classic" disciplines. But they are young sciences, often full of enthusiasm and ferments that distance them from the rigor of a wiser maturity. The technique has now become the subject of the story. In a society that cannot but call itself technological, the intersection between deterministic cultures, of more or less exact sciences, and human cultures, which are inherently heuristic and in many ways random, is such that talking about machines and systems of production also means talking about men and philosophies.
