Giancarlo Bernasconi

Sensitivity analysis of marine Controlled-Source Electromagnetic data

Electromagnetic sounding methods represent one of the few geophysical techniques that can provide information about the state and the properties of deep continental crust and upper mantle. In particular, marine Controlled-Source Electromagnetic (mCSEM) method is being applied to offshore hydrocarbon exploration and providing encouraging results, as it can complement the information obtained from seismic elaborations, mainly the position of the elastic discontinuities, with a map of electrical conductivity, the principal “discriminator” between conductive water-bearing rocks and non-conductive hydrocarbon accumulations. The processing of mCSEM data can be problematic due to the non-uniqueness of the solution, the environmental and equipment noise, and the high computational power required when dealing with 3D inversion. This paper proposes a simplified procedure to study and rank the sensitivity of mCSEM in a canonical 1D scenario, with a single resistive anomaly embedded in a homogeneous background. We analyze the sensitivity of the data with respect to the most important test parameters, namely the frequency, target depth, thickness, and resistivity. In addition, this procedure is also utilized to validate the so-called Tequivalence theorem. The results of this study could assist the interpreter to highlight the reliability of the inverted parameters in a complex inversion environment.

Sharp CSEM Inversion by Means of Geological Structural Constraints

A novel implementation of 2.5D CSEM forward and inversion modelling is presented: a finite element forward modelling which creates the simulated CSEM data and an iterative Bayesian inversion that compares the simulated and measured data in order to obtain physical information about the domain. The forward modelling makes use of geometrical information, derived from seismic data, that divides the domain in several regions, each one having different properties. The accurate description of geological structures is ensured by a parallel Finite Element forward modelling, running on parallel clusters. Concerning the inversion, the standard Tarantola method has been made more solid by using a full covariance matrix that acts as a stabilizer and smoother, but conserving discontinuities between different regions. Furthermore, bi-logarithmic boundaries help to constrain the problem according to prior information. The presented techniques have been tested on a real dataset, showing consistency with different approaches and validating our method.

Coloring c-Si PV cells: A new structure

Colored c-Si PV cells or modules will allow a wider spread of Building Integrated Photovoltaic (BIPV) both on traditional roofs and on building facades. A few commercial products range from mono or multi crystalline colored PV cells to colored front protecting glasses. In this paper a new colored PV cell structure based on c-Si PV cells is presented and analyzed. Comparison with the simulations of other implemented solutions is also presented and discussed.

Optimized Sequence of Single-domain and Joint Inversions Using Quantitative Integration Systems (QUIS)

Summary In this paper we discuss a “systemic approach” for integrating multidisciplinary geophysical data. We apply a Bayesian inversion algorithm to perform a sequence of single domain and joint inversions of seismic and electromagnetic data. We show how this integration workflow allows accurate estimations of porosity and fluid saturation. We extend this approach also to gravity data combining cooperative modeling, single domain inversion and joint inversion for integrating real multidisciplinary data sets in the Barents Sea.

Investigation of symmetry attribute analysis on the phase measurements of marine controlled-sourceelectromagnetic surveys

In this paper we study the potential of symmetry attribute analysis applied to the phase component of electric field observations of marine controlled-source electromagnetic data. The effectiveness of symmetry attribute analysis on the phase component of marine controlled-source electromagnetic data in detecting the boundaries of resistive layer(s), such as hydrocarbon accumulation, is investigated. A comparison between symmetry attribute analysis on the phase and magnitude component of 2.5D synthetic data and a real data set is also discussed. The results presented a clear response indicative of the locations of the subsurface resistors. The phase symmetry attribute analysis proved to be effective for qualitative detection of the lateral extent of embedded resistors.

Gas Filled Pipelines Monitoring Using Multipoint Vibroacoustic Sensing

eni S.p.A. has promoted and supported a research project (DIONISIO) for the design of a proprietary pipeline monitoring system, exploiting negative pressure waves and statistical analysis principles. A discrete network of pressure and vibration sensors are installed on the pipeline, at relative distances of tens of kilometers. The acoustic and elastic waves produced by third party interference and by flow variations (leaks, spills, valve regulations, pig operations, etc.), propagate along the pipeline, and they are recorded at the monitoring stations. Multichannel processing of the collected signals enables the real time detection, localization and classification of the triggering event.The system has been tested in single phase and multiphase transportation lines during several field campaigns. This paper collects the results for gas transportation pipelines.The field experience has been used to upgrade the prototypal version of the system to an industrial version, that is currently operative, or in an advanced installation phase, on several pipelines in Italy and in Nigeria, and it has detected tens of bunkering activities with a localization accuracy of about 25 m, from a distance up to 35 km from the sensing point.Copyright

Advanced Real Time and Long Term Monitoring of Transportation Pipelines

A key factor for the sustainable development of oil&gas industry is the remote monitoring of integrity and reliability of transportation pipelines. In order to mitigate the risk associated to third party interference (TPI) risks and to minimize the environment exposure, it is possible to deploy a Multipoint Acoustic Sensing (MAS) technology which makes use of multi sensors placed at discrete distances along the pipeline. Any interaction with the pipe generates acoustic waves that are guided within the fluid (gas, oil, products or water) for long distances, providing information on the source event and on the “transmission” channel. Acoustic propagation is mainly governed by both absorption coefficient and sound speed, which in turn are functions of the pipe, fluid and surrounding medium system. These features have been analyzed by processing real-time data collected with a proprietary MAS system (e-vpms™) on fluid transportation pipelines, in different operational and flow service conditions, producing exhaustive sets of TPI actions, leak trials and tracking pig inspections. The paper presents original procedures for real-time monitoring, as well as for long term supervision and advance intervention planning.