Abstract

Current trends in the oil and gas industry are focused more in operational efficiency, production optimization, value, and environmental effects than ever before. The industry actively pursues technologies and techniques that offer improvement in these areas, which explains the increased interest in multilateral well designs. In highly sensitive areas, such as national parks and areas of geographical sensitivity, it has become extremely difficult to obtain permits to prepare well sites if this preparation requires the removal of forestry, permanent scarring of the landscape, or disturbances to the wildlife or to the people who live and work in the area.

The Val d'Agri field in southern Italy is located within the boundaries of the Basilicata National Park. Consequently, Eni and its partners were challenged with reaching production targets while minimizing land disturbances. Eni evaluated and implemented multilateral technology to help meet the objectives.

The forward thinking of Eni led the company to pre-install orientation devices in the casing string during the original construction of the well. This action made it possibile to perform multilateral solutions if/when needed, such as the TAML Level 5 implemented on well Agri-1 or B.

The first orientation devices to be used were installed in well Cerro Falcone 3X or A in 2000 to construct a TAML Level 2 junction with re-entry capabilities through the completion. In 2003, the same technology was used on Agri-1 or A, where the orientation devices were installed in the 7-in. and 9–5/8-in. casings. When well Agri-1 or A was put on production, the produced fluid was found to be much more corrosive than expected. The well had to be shut in because the metallurgy of the equipment in the well was not suitable for the corrosivity of the produced fluid.

Eni and Halliburton formed a team to evaluate the situation and design a suitable solution: to exit from the 9 5/8-in. orientation device and drill a secondary lateral. This secondary lateral required a TAML Level 5 junction with an Incoloy 925 completion to isolate the junction and to provide through-tubing access to all bores, including the existing Agri-1 or A.

This paper focuses on the methodology and value this technology brought in the achievement of planned production targets.

Introduction

Finding the correct balance between environmental protection and economic progress provides challenges, especially for the oil industry. The commitment to the environment has been achieved by planning the operations on the basis of environmental studies and analysis that made it possible to minimize any effect that the oil industry activities might have on the natural environment.

The largest fields in Italy are located in very sensitive areas, both onshore (Val d'Agri field of southern Italy and Trecate field of northern Italy) and offshore (Adriatic Sea).

Val d'Agri is the largest oil discovery ever made in Italy. The area is located in the Basilicata region (Fig. 1) in a part of the Southern Apennine (Campano-Lucano Arc), which, from a geological standpoint, constitutes an extremely complex context. Val d'Agri is also an area of considerable environmental sensitivity because 30% of the Basilicata region is a naturally protected area and the exploration and production concessions cover ample wooded areas and/or areas with high naturalistic and historical interest.

For these reasons, the Val d'Agri project has required a great effort by Eni and the service companies. The complexity of this project requires the introduction of highly innovative solutions and technologies. In response to the environmental considerations and concerns, the following technologies were evaluated and implemented:

  • Clustering

  • Straight hole drilling device (SDD)

  • Lean Profile technology

  • Closed-loop system

  • Compact wellhead and horizontal Christmas tree

  • Multilaterals

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