Outstanding Production Performance Through the Extreme-Lean Profile Well Design: an Example of Drilling Operational Excellence that Allowed Reaching the Reservoir Target with a Bigger Hole Size in a Mature Field

Abstract

This paper highlights how the implementation of an extreme lean casing profile for the well construction, can really make the difference to achieve operational excellence. This is the case of the successful application in a mature field, where, for the first time, the reservoir target has been reached with a horizontal 8½Љ hole section within naturally fractured carbonate formations.In such occasion, the extreme lean profile has made it possible to reach the reservoir with a bigger production hole diameter, compared to the previous wells drilled in the same area; this has allowed the accomplishment of an outstanding production performance, also thanks to the lower pressure losses inside the 8 ½Љ open hole section.The reduced clearance between casing and borehole represents a distinctive characteristic of the extreme lean profile; this enables using two additional casing strings, as a contingency for well construction or as extra casings to reach deeper targets with the same production hole diameter or, as in this case, start with a smaller surface hole while simultaneously reaching the reservoir with a production hole diameter larger than those of conventional wells.Furthermore, the specific well design has allowed to reduce the drilling time, improve borehole stability thanks to the smaller hole sections, and decrease the environmental impact as a result of the reduced volume of cuttings produced.This paper provides a comprehensive description of the well requirements, the associated operational issues, the chosen solutions and the actual challenges encountered during drilling operations. The achieved results are also described.