This paper presents a novel approach for the formation evaluation of shaly-sand thin layered reservoirs using dielectric dispersion wireline logging provided by a new generation tool. The study is focused on gas fields in the Mediterranean basin characterized by the presence of very thin inter-laminations (centimeter-scale or even less). In these complex reservoirs, the conventional petrophysical analysis is very challenging due to standard logging tools' vertical resolution limits which prevent the quantitative estimation of the clay content, of a detailed water saturation profile and of the reservoir quality.The new-generation, cm-scale vertical resolution tool overcomes these limitations thanks to the continuous measurement of dielectric dispersion from the MHz to the GHz frequency range and to a fit-for-purpose inversion based interpretation model. The outcome is a high resolution estimate of the main petrophysical parameters including water volume fraction for determining hydrocarbon saturation, formation water salinity and an additional textural parameter of the rock matrix that is correlated to clay volume.The model has been developed and calibrated using a statistically representative database of core measurements (including porosity, mineralogy, granulometry, Cation Exchange Capacity as well as dielectric spectra measurements) from several wells drilled in shaly-sand reservoirs representing different geological environments. In all the analyzed wells a full wireline log data set was also available.The application of the new approach to the examined case histories provided satisfactory, high resolution results in terms of:• lithological description of the formation with the added value of a quantitative estimation of the clay content; • reservoir quality evaluation;• gas saturation indicator thus reducing the uncertainty in the petrophysical characterization of complex shaly-sand reservoirs.

The positive experience and results obtained by using a new class of high temperature / high pressure (HT/HP) logging while drilling (LWD) tool in a slimhole (5–3/4-in.) exploration well in Italy's Po Valley opens new possibilities for trajectory and stratigraphic control while drilling in deep, HT/HP wells. Using the LWD suite, the operator was able to acquire real time, continuous temperature, gamma ray and resistivity data for analysis and correlations at 180°C (356°F) and 16,780 psi - conditions previously unachievable. As a result, the operator pinpointed the stratigraphic position of a main direct fault that raised the upper reservoir above the prognosis estimation and was able to:achieve critical placement of the casing shoe to avoid a well control hazard posed by drilling into a partially depleted reservoir;drill continuously without having to pull the bottomhole assembly out of the hole and change bit types for better, unaltered cuttings; andidentify a carbonate sequence in the lower section, which ultimately led to the decision to plug and abandon the lower section and produce the upper reservoir, with very good results. Real time annular temperature measurements provided accurate temperature data for mud program optimization and operational considerations that are not usually available in exploration wells. This paper will discuss the characteristics and operating limitations of the Villafortuna-Trecate HT/HP field; the objectives of the Cascina Cardama 1 Dir well; the LWD planning and implementation, and the operations, logs and results. Based on the experience and results of this well, the operator will continue to use the high temperature LWD suite to drill future wells and projects. Introduction - High Temperature (HT) / High Pressure (HP) drilling: searching for hydrocarbons in deep wells The original definition of high temperature (HT) /high pressure (HP) was first introduced by the Department of Trade Industry (DTI) for the United Kingdom Continental Shelf (UKCS). It was defined as "Where the undisturbed bottom hole temperature at prospective reservoir depth is greater than 149°C (300°F) and the maximum anticipated pore pressure of any porous formation to be drilled through exceeds 18,000 Newton/meter2/meter (0.8 psi/ft) or around 10,000 psi". Other industry bodies use a different definition. For example, the Norwegian Petroleum Directorate (NPD) defines HT/HP wells as deeper than 4,000 m true vertical and/or having an expected wellhead shut-in pressure exceeding 69 MPa (10,000 psi) and/or having a temperature exceeding 150°C. These definitions are more restrictive and require a more extensive technical interpretation of potential conditions for each well. The first challenge in drilling a HT/HP well has been from pressure surges or kicks that have caused the majority of HT/HP incidents reported to health and safety managers. Drilling practices and well control procedures have been refined jointly with rig owners, and drilling crews are given well specific training to handle kick situations safely, quickly, and confidently.

TX 75083-3836 U.S.A., fax 01-972-952-9435. AbstractRadioactive chemical logging sources have been used in the E&P industry for many years to help operators obtain valuable information about their reservoirs. Until recently, much of the information obtained using these sources could not be obtained with any other method. While the potential risks involved with the use of such sources have always been known, more awareness in the industry has led to increased efforts towards the reduction or even elimination of the use of chemical sources where possible.A new Logging-While-Drilling (LWD) tool has been developed, using innovative technology to provide a complete suite of formation evaluation measurements without having to use a chemical radioactive logging source. The use of a nonchemical radioactive source significantly reduces the environmental and operational risks normally involved with traditional LWD tools.The data delivered by this service include not only the traditional measurements such as gamma ray, resistivity, density, and neutron porosity, but also measurements not previously available in LWD such as formation capture cross section (sigma) and elemental analysis from neutron capture spectroscopy used to compute formation mineralogy. An entirely new LWD measurement has also been introduced with the tool, making it possible for the first time to determine formation density without the use of a chemical logging source.A case study is presented of a well situated in a field in southern Italy, inside an environmentally sensitive national park. Because of the location of the well, it has not been possible to use radioactive logging sources for formation evaluation. As a result, fully evaluating the reserves has been an ongoing challenge for the operator. In addition, because of the move towards high angle and horizontal wells, wireline

The huge number of horizontal wells drilled in complex reservoirs and the development of more accurate logging while drilling (LWD) technologies offer to the oil&gas companies the opportunity to reduce operational risks and save time and costs, by replacing wireline acquisition with LWD tools. This paper describe a new acquisition strategy based on advanced LWD tools recently made available also in 6" hole size. Thanks to this technology it was possible to provide a reliable reservoir characterization and to identify the best fluid path in horizontal infilling wells drilled into tight and fractured carbonatic reservoir. Economic and HSE aspects have been strongly considered in the illustrated strategy. The integrated analysis of advanced sonic and resistive image while drilling logs provided the essential information to quantify the matrix and the secondary fractured porosity as well as the "mixed" porosity, and, in addition, fundamental data to clarify the reservoir quality where Tough Logging Conditions (TLC) cannot be through. The acoustic compressional arrivals contribute to porosity evaluation while the Stoneley waves interpretation allowed the detection of "open" natural fractures. In addition, recognized "open" fractures have been matched with mud losses events, Gas While Drilling and temperature profile. The producible intervals identified by the illustrated methodology agree with the response of the main production results. The approach has been validated by means of an accurate comparison between wireline and while drilling logs response, both available along an interval of a reference well section. The LWD technology has shown its capability to capture the different scale of phenomena occurring into fractured reservoirs. Thanks to the combination of technology, knowledge and people, well data acquisition can be conducted safely and with significant saving in term of operating time reduction. The additional information about fluid path detection can improve the efficiency of the well completion. INTRODUCTION AND SCOPE OF WORK The strong and continuous need to drill and produce high deviated or horizontal wells in the oil business was a heavy impulse to change vision on tool conveyance method moving from Wire Line (WL) to Logging While Drilling (LWD) acquisitions. The service companies in the last years spent a lot of effort in the LWD tool development and now days the quality and the completeness of the last generation LWD is comparable with the wire line technology in most case, and more useful in others. The operators choose the logging data acquisition strategy, while drilling or after drilling, based on project requirements. The LWD tool application not only can provide good performance but can also be an important opportunity to increase efficiency and safety. Few technologies have had a larger impact on these results than Logging While Drilling (LWD).

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