New Approach To Deep Water Long Production Testing
Authors: Cerrito Emilio , Ciprigno Maurizio , Picciani Franco 
Published: October 2008

The Aquila project guidelines and actual results will be discussed in this paper. Drilling features (in particular the drilling information system and the drilling of the drain hole), the completion and the long production test using a tanker for storage will be discussed. The logistic and environmental problems associated with the mooring system, including the tanker, will also be covered.

INTRODUCTION

Deep water hydrocarbon reserves are considered one of the most promising frontiers for E&P activity in the near future. Technology, considered as a combination of innovator equipment and experience, will play a leading role in providing an economic and safe means of confronting the emerging deep water challenges. The southern Adriatic Sea is an area of high hydrocarbon potential in deep waters. This basin is located in water depth of 500-1000 m. The first investigation, dating back to the late Seventies gave encouraging results (fig. 1).

However, the technology available at that time did not offer any acceptable technical and economical solutions in order to test the well on a viable way. With advances in deep water completion technology it has become possible to adequately manage environmental and safety constraints.

The Aquila appraisal well was drilled in 820 m of water and an LPT was performed, using a last generation moored semisubmersible rig, assisted by a storage tanker. Facilities were designed to meet local regulations concerning environmental aspects and the sour gas content of the produced crude.

The drilling activity was monitored in real time at the AGIP Ortona District and at the Company's headquarters in Milan through the in-house developed "Advanced information Drilling System" (ADIS). nother challenge was the development of a safe and reliable surface, storage and transport system in an area where weather conditions can become really severe.

A project of such complexity required multidisciplinary tasks and the adoption of the most advanced technologies. Although technology concerning completion aspects can be considered as relatively new, it still requires careful evaluation for specific field application.

Further studies on the implementation of subsea production equipment for water depths in excess of 800 m are in progress.

SYSTEM DESCRIPTION AND GENERAL PREMISES

A production test, consisting of continuous production from the Aquila drain hole, lasted 85 days.

Testing equipment was installed on the same semisubmersible platform used for drilling.

The produced and treated oil was conveyed from the semisubmersible through a flexible buoyant line to a storage tanker moored to the platform (fig. 2).

CHARACTERISTICS OF THE SYSTEM

Drilling rig.

The FGL-1020 trendsetter R&B "Jack Bates" drilling rig was used. H was equipped with thrusters and a mooring system that allows safe mooring in water depth in excess of 1000 m, with 18 ¾"-15,000 psi multiplex BOP stack and a lower marine riser package (LMRP) quick reacting time (20 sec.).

The platform was designed to work under particularly severe weather conditions and to allow "zero discharge".