From Lean to Extreme-Lean Well Profile: Field Experience in the Mediterranean Sea

Abstract

The main subject of this paper will be to outline the field experience achieved with a new type of well profile and directional drilling system. Reducing the cost of well construction has been a driver for many new technologies. The lean casing profile introduced by Eni SpA, the major Italian oil and gas company, about a decade ago was a successful step towards lowering the drilling and completion cost in the vertical, top-hole section. Automated vertical-drilling tools have been the technical enabler of such a concept. Recently, this oil company has moved further towards an even more radical "extreme-lean well profile." This paper gives a brief insight into the well-design concept and the enabling technology behind it. The drilling technology is based on the well-known automated vertical-drilling system, which has been enhanced by the capability to drill an enlarged hole size below a casing without compromising the verticality and hole quality. In the main part of the paper, two field applications, in the Mediterannean Sea and offshore Egypt, are described. The paper will also cover the lessons learned especially from the second of the first two field applications. The extreme-lean well profile and automated vertical-reaming technology can provide value to several drilling campaigns not only through the reduction of well-construction cost. Another major benefit is the ability to run an intermediate casing string, if required because of difficult well conditions, and still arrive at the same diameter of casing in the reservoir. The completion concept and the enabling tool technology are very unique and have not been available to the industry until recently.