In reservoir engineering, one of the main sources of information for the characterization of reservoir and well parameters is well testing. An alternative to the standard drawdown/buildup test is ...Harmonic Pulse Testing (HPT) because it can provide well performance and reservoir behavior monitoring without having to interrupt field production, which is appealing from an economic standpoint. Recorded pressure analysis is performed in the frequency domain by adopting a derivative approach similar to conventional well testing. To this end, pressure and rate data must be decomposed into harmonic components. Test interpretability can be significantly improved if pressure data are detrended prior to interpretation, filtering out non periodic events such as discontinuous production from neighboring wells and flow regime variations that did not respect the designed test periodicity. Therefore, detrending offers the possibility of overcoming the limitation of HPT applicability due to the difficulty of imposing a regularly pulsing rate for the whole test duration (typically lasting several days). This makes HPT attractive for well performance monitoring, especially in gas reservoirs converted to underground gas storage. In this paper, different detrending methodologies are discussed and applied to synthetic and real data. Results show that, if a proper detrending strategy is adopted, information provided by HPT interpretation can be maximized and/or improved.
The understanding of multiphase flow phenomena occurring in porous media at the pore scale is fundamental in a significant number of fields, from life science to geo and environmental engineering. ...However, because of the optical opacity and the geometrical complexity of natural porous media, detailed visual characterization is not possible or is limited and requires powerful and expensive imaging techniques. As a consequence, the understanding of micro-scale behavior is based on the interpretation of macro-scale parameters and indirect measurements. Microfluidic devices are transparent and synthetic tools that reproduce the porous network on a 2D plane, enabling the direct visualization of the fluid dynamics. Moreover, microfluidic patterns (also called micromodels) can be specifically designed according to research interests by tuning their geometrical features and surface properties. In this work we design, fabricate and test two different micromodels for the visualization and analysis of the gas-brine fluid flow, occurring during gas injection and withdrawal in underground storage systems. In particular, we compare two different designs: a regular grid and a real rock-like pattern reconstructed from a thin section of a sample of Hostun rock. We characterize the two media in terms of porosity, tortuosity and pore size distribution using the A* algorithm and CFD simulation. We fabricate PDMS-glass devices via soft lithography, and we perform preliminary air-water displacement tests at different capillary numbers to observe the impact of the design on the fluid dynamics. This preliminary work serves as a validation of design and fabrication procedures and opens the way to further investigations.
When the mind turns more than one would wish towards questions of - as W.G. Sebald puts it - the "natural history of destruction", comparative consideration by artists and interdisciplinary scholars ...is directed to the interstices between images, novel, essay, (auto)biography, memorial and travelogue. Artists have been among Sebald's most prolific interpreters - as they are among the more fearless and holistic researchers on questions concerning what it means never to be able to fix an identity, to tell a migrant's story, or to know where a historical trauma ends. Sebald has - as this book attests - also given artists and scholars a means to write with images, to embrace ambiguity, and to turn to today's migrants with empathy and responsibility; as well as to let academic research, creation and institutional engagement blend into or substantially inform one another in order to account for and enable such necessary work in the most diverse contexts.
Underground fluid storage is gaining increasing attention as a means to balance energy production and consumption, ensure energy supply security, and contribute to greenhouse gas reduction in the ...atmosphere by CO2 geological sequestration. However, underground fluid storage generates pressure changes, which in turn induce stress variations and rock deformations. Numerical geomechanical models are typically used to predict the response of a given storage to fluid injection and withdrawal, but validation is required for such a model to be considered reliable. This paper focuses on the technology and methodology that we developed to monitor seabed movements and verify the predictions of the impact caused by offshore underground fluid storage. To this end, we put together a measurement system, integrated into an Autonomous Underwater Vehicle, to periodically monitor the seabed bathymetry. Measurements repeated during and after storage activities can be compared with the outcome of numerical simulations and indirectly confirm the existence of safety conditions. To simulate the storage system response to fluid storage, we applied the Virtual Element Method. To illustrate and discuss our methodology, we present a possible application to a depleted gas reservoir in the Adriatic Sea, Italy, where several underground geological formations could be potentially converted into storage in the future.
Concerning the emerging power-to-gas technologies, which are considered the most promising technology for seasonal renewable energy storage, Underground Hydrogen Storage (UHS) has gained attention in ...the last few years. For safe and efficient storage, possible hydrogen losses due to dissolution into the aquifer must be estimated accurately. Due to safety concerns, experimental measurements of hydrogen solubility in brine at reservoir conditions are limited. In this study, a PVT cell is used to characterize the solubility of hydrogen and its mixtures with methane in saline water/brine. The experiments were carried out at 45, 50, and 55°C and from 1 bar up to 500 bar, mimicking a significant range of possible reservoir conditions. Two brine samples representative of two different reservoirs were tested. Two mixtures of methane and hydrogen (10 mol% H 2 and 50 mol% H 2 , respectively) were considered, along with pure hydrogen, to account for the presence of methane in the primary phase of hydrogen storage in a depleted gas reservoir. In the current paper, a comparison of the experimental results with literature models is provided. At the experiment conditions, the impact of the differences in the composition of the two analyzed brines as well as the impact of the analyzed range of temperatures was not significant. Conversely, a non-negligible variation in terms of the slope of the solubility curve was observed as a function of the gas mixture composition: the curve increased more steeply as the percentage of hydrogen reduced.
New hypotheses for reusing platforms reaching their end-of-life have been investigated in several works, discussing the potential conversions of these infrastructures from recreational tourism to ...fish farming. In this perspective paper, we discuss the conversion options that could be of interest in the context of the current energy transition, with reference to the off-shore Italian scenario. The study was developed in support of the development of a national strategy aimed at favoring a circular economy and the reuse of existing infrastructure for the implementation of the energy transition. Thus, the investigated options include the onboard production of renewable energy, hydrogen production from seawater through electrolyzers, CO2 capture and valorization, and platform reuse for underground fluid storage in depleted reservoirs once produced through platforms. Case histories are developed with reference to a typical, fictitious platform in the Adriatic Sea, Italy, to provide an engineering-based approach to these different conversion options. The coupling of the platform with the underground storage to set the optimal operational conditions is managed through the forecast of the reservoir performance, with advanced numerical models able to simulate the complexity of the phenomena occurring in the presence of coupled hydrodynamic, geomechanical, geochemical, thermal, and biological processes. The results of our study are very encouraging, because they reveal that no technical, environmental, or safety issues prevent the conversion of offshore platforms into valuable infrastructure, contributing to achieving the energy transition targets, as long as the selection of the conversion option to deploy is designed taking into account the system specificity and including the depleted reservoir to which it is connected when relevant. Socio-economic issues were not investigated, as they were out of the scope of the project.
This paper presents a critical review and the state of the art of graphene porous membranes, a brand-new technology and backdrop to discuss its potential application for efficient water desalination ...in low salinity water injection (LSWI). LSWI technology consists in injecting designed, adequately modified, filtered water to maximize oil production. To this end, desalination technologies already available can be further optimized, for example, via graphene membranes, to achieve greater efficiency in water-oil displacement. Theoretical and experimental applications of graphene porous membranes in water desalination have shown promising results over the last 5-6 years. Needless to say, improvements are still needed before graphene porous membranes become readily available. However, the present work simply sets out to demonstrate, at least in principle, the practical potential graphene membranes would have in hydrocarbon recovery processes.
The finite volume method has been successfully applied in several engineering fields and has shown outstanding performance in fluid dynamics simulation. In this paper, the general framework for the ...simulation ofnear-wellbore systems using the finite volume method is described. The mathematical model and the numerical model developed by the authors are presented and discussed. A radial geometry in the vertical plane was implemented so as to thoroughly describe near-wellbore phenomena. The model was then used to simulate injection tests in an oil reservoir through a horizontal well and proved very powerful to correctly reproduce the transient pressure behavior. The reason for this is the robustness of the method, which is independent of the gridding options because the discretization is performed in the physical space. The model is able to describe the phenomena taking place in the reservoir even in complex situations, i.e. in the presence of heterogeneities and permeability barriers, demonstrating the flexibility of the finite volume method when simulating non-conventional tests. The results are presented in comparison with those obtained with the finite difference numerical approach and with analytical methods, if possible.
The increasingly rapid development of the disciplines of petroleum engineering and petroleum geology has led to new methodologies and interpretation techniques forming new knowledge that should be ...offered quickly and efficiently to modern engineers and geologists. This need is equally important for students as well as for young professionals. Access and training to all scientific information is necessary to ensure success in their future careers. Today, e-learning has become a common medium for the management and distribution of on-line educational content. Learning Management Systems （LMSs） were not only developed to handle a large variety of multimedia content that provides an organized knowledge repository used to accelerate access to information and skill acquisition; but, LMSs can also keep detailed statistics on the use of the available material offering a powerful training and educational tool. In this document, the Petroleum Knowledge Tutorial System, an LMS platform offering a variety of online educational and training options to petroleum engineers and geologists, is presented. It was created using Moodle, open- source software that can be used to create on-line courses. The platform covers fundamental educational concepts in a structured way. It follows an optimized ＂workflow＂ that can be applied not only to solve a specific exercise but also any similar problem encountered over the course of one＇s career. The platform was designed to offer a repository of learning material in various forms and to favor user-platform interactions. It can be used for training and evaluation purposes through exercises and problem solving that the user can perform online by using browsing software along with internet access. Special tools were created and implemented on the platform to assist the user in completing a variety of tasks including performing exercises involving calculations with given data and plots of points or lines on graphs without leaving the learning environment. Furthermore, videos with detailed explanations follow each learning module and provide the full solution to every exercise. The LMS automatically keeps a large statistical database including the users＇ access to activities on the platform that can be exported and further processed to improve the platform functionality and evaluate the users＇ performance.
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