Electrical logging is now almost universally applied in oil and gas fields throughout the world. The usual practice is to record the self‐potential and resistivity curves which, together, reveal the location and thickness of strata penetrated by the drill and a great deal as to their lithology and fluid content. The resistivity log thus obtained serves very well to disclose in detail formations penetrated and to distinguish between oil and water. With the device used for ordinary electrical logging purposes, the true resistivity of the formation is not measured. The recorded resistivity is only an apparent value which is governed by several influencing factors, besides the true resistivity of the formation and its fluid content. As applied to the oil content of a formation, it is a qualitative measurement, merely showing the vertical extent of the oil accumulation. Experience has shown that the electrical conductance of oil sands is due to connate water held by molecular forces to the sand grains. Research has disclosed a definite mathematical relationship between the true resistivity of an oil sand and the ratio of its oil and connate water. This leads the way to a new practical application of electrical logging. By using a suitable combination of measuring devices, the true resistivity of an oil sand may be measured in an oil well. The true resistivity measurement, used in conjunction with other field and laboratory data, may in certain cases be used quantitatively to make a determination of the net oil content of a productive layer. The method by which these measurements are obtained is described and actual examples are cited.

The knowledge of reservoir fluids phase behavior has always played an important role in oilfield development planning, reserves evaluation and screening of the potential for enhanced oil recovery. Nowadays operators aim more and more at fast-track development of discovered resources, therefore, any anticipation of thermodynamic properties is a business challenge: looking for "PVT-analogues" is the solution proposed in this paper. What adversely impacts massive scouting of PVT data usually is the limit of a small amount of readily available information, also due to the intrinsic complexity of the datasets and of the variety of output formats produced by different laboratories all over the world and over the years. In Eni a new tool for data mining based on the reorganization and thorough digitalization of the PVT archive is in advanced development. Standardization of the laboratory outcomes by templates, automatic loading into a corporate repository, in-house development of software tools for quality control, data mining and advanced statistical analyses, easy access through a properly designed interface: each of these steps is integrated in an upgraded data-driven approach to fluid properties prediction allowing an earlier understanding of the reservoir fluid system.

With the aim of improving the understanding of production behaviour in a multi-discovery asset and the evaluation of near-field exploration opportunities, an integrated study has been carried out involving three different disciplines: Fluid Thermodynamics (PVT), Organic Geochemistry and Petroleum Systems Modelling (PSM). The synergistic workflow has been undertaken starting from an accurate quality check of the initial dataset related to fluid samples and lab tests. By merging PVT and geochemical data, it was possible to carry out a robust statistical survey and explore correlations across different parameters and features; in this way, strict connection among many physical parameters and some oil maturity and biodegradation indices were identified. In the following step, after geo-referencing the fluid samples in the framework of the Petroleum Systems Model and tracking the locations of the source rocks, a reliable interpretation of the oil expulsion and migration history became possible over the whole reservoir fluid system. Finally, taking into account the simulated fluid phase envelopes, further insights were drawn in terms of the fluid phase behavior in different areas, contributing to reduce uncertainty and exploration risk for future activity in nearby prospects.