Deep Water

To reduce the risks associated with deep-water and ultra deep-water basins before exploration starts, Eni developed advanced technologies for basin modelling and petroleum systems assessment.

• A widely used system is the  advanced numerical modelling for petroleum system evaluation SEBE 3, an integrated 3D basin modelling software, based on finite elements theory, designed to assess the petroleum potential and the associated risk of undrilled prospects, i.e. ‘traps' not yet reached by exploration wells.
• Once the most promising areas have been selected,  3D seismic prospecting is used to gather seismic data aimed at the three-dimensional determination of the spatial position of deep layer.
• Deep water seismic data are typically affected by strong multiple reflections, which prevent effective time and depth imaging, quantitative seismostratigraphic and petrophysical interpretation. New generation demultiple methodologies (3D SRME) were recently developed, which are able to predict surface multiples just from seismic data, with no apriori information about velocities or reflector picking.
• Effective tools for the accurate definition of the geological-depositional model and the detection of geological bodies that may represent exploration prospects are used, principally volumetric interpretation and advanced technologies for multi-attribute analysis and 3D seismic visualization. 3D pre-stack depth migration (3D PSDM) is the most advanced tool for seismic imaging in complex geological environments with strong lateral velocity variations and deep steeps (i.e. salt tectonics, thrusts).
• To better integrate the geological and geophysical information into the reservoir  model and make the structural and sedimentological models more reliable, it is necessary to "see in depth". This is done using stratigraphic inversion techniques (seismic lithology), including the Joint Inversion Interpretation, based on the integration of depth interpretation (Pre Stack Depth) with two advanced geophysics tools: 3D Full Tenor Gravity - 3D FTG and Marine Magneto Telluric – MMT, which allow an accurate reconstruction of the subsurface geology in structurally complex areas (sub-salt and sub basalt exploration).
• Sea Bed Logging - SBL is an application of marine controlled source electromagnetic (CSEM) sounding, that can improve the accuracy in detecting and characterising hydrocarbon reservoirs in deepwater areas. By studying the EM response in terms of signal variation relative to source - receiver geometry (magnitude vs. offset), the resistivity structure of the subsea formations can be determined. A hydrocarbon filled reservoir will typically have a higher resistivity than shale and water filled reservoirs and thus it can be identified by SBL. SBL is a direct hydrocarbon indicator (DHI), which can be fully integrated with seismic methods.
• It is necessary to obtain information of both the origin of the oil and its distribution within the reservoir as well as on the formation of the accumulation. For this it is necessary to use advanced technologies for the characterization of oil samples such as GICOS – Geochemical Integrated Characterization of Oil samples.
  

In deep water and ultra deep drilling activities some systems have been improved in order to overcome the worst operational difficulties at reasonable cost:

• SDD - Straight-Hole Drilling Device is a device to ensure continued monitoring of the drilling, so that proceeds vertically, both in  individual or clusters of wells, on land or at sea;
• Lean Profile: technology based on achieving a drastic reduction of the clearance between casing and open hole (up to 1-1.5 inches for the entire well profile), which ultimately leads to a reduction of bit and casing diameters for the upper part of the well keeping the same production casing size. The technology is applied for vertical and deviated wells allowing reduction of operational times and costs while drastically reducing the volume of waste produced. Further benefits include the possibility of clusterization of onshore wells in complex geological environment. Recent applications of the lean technology also refer to ultra deep HP/HT vertical and deviated wells.
• Autotrak: advanced drilling directional system that makes it possible to steer a well-path while continuing to rotate the drill string.
• VertiTrak: a drilling tool capable of maintaining an accurate control of vertical direction providing, among other advantages, increased ROP (Rate of Penetration), better hole stability and a low level of tortuosity in the well, thus reducing dramatically the friction in the well.
• Dual Casing Running: advanced deep-water drilling technology. The riserless sections are drilled in one run, thus setting and cementing the surface and conductor pipe simultaneously. This new, patented methodology drastically reduces the time and cost of the well construction.
  

In deep water and ultra deep water production very advanced treatment technology applications are applied to develop offshore fields  characterized by deep-water, high water percentage, low pressure in reservoir, complex subsea configurations, long connections and transportation problems in the case of fluids.
Eni is currently evaluating completely underwater development scenarios, with the application of subsea processing units (separators, pumps, etc..) that are already available or under development or qualification. The application of such systems can have positive effects on investment and operating costs and on environmental impact, both for new scenarios and for marginal fields in the vicinity of existing structures.

The innovative solutions that have been developed include:

• Smart Completion, an intelligent completion system (the preparation for production of an already drilled well) which can perform monitoring, remote control and self-diagnostic functions using surface controlled tools;
• Fiber optic-based offshore structural monitoring system for the long-term structural monitoring of metallic risers, the collectors used in offshore wells to connect underwater wellheads with the surface;
• Subsea processing (SSP) technologies, the application on seabed of any operation meant to condition, separate, boost, measure or dispose fluids and solids produced by subsea well. The long term/high level target of Subsea Processing (SSP) is to provide the capability to produce hydrocarbons from offshore fields without the need of offshore platforms or floating systems (Zero Surface Facilities). Such a way of producing oil and gas promises to be more economically effective and more environmentally friendly than nowadays approach, based on extremely costly floating or fixed platforms. Eni E&P will be committed to develop fields in areas where severe environmental conditions could impose a completely subsea development scheme, with long tie-back for sending the production to shore and the consequent need to install processing equipment on the seabed.
  In the framework of many R&D projects, Eni is active on several important issues of subsea processing technologies. During last years Eni’s activity has been mainly voted to develop, qualify and test in pilot sites technologies related to: 
  
  • Subsea oil/gas separation (VASPS)
  • Subsea multiphase boosting (twin screw technology)
  • Subsea metering (oil-in-water meters, multiphase and wet-gas meters)