Abstract
Well FUL-19L is located at the north flank of the Furrial Field in the State of Monagas, Venezuela. It was completed in 1991 at a depth of 15,150 feet (4,617.72 m) through a double string design, and was in production of 7,722 BPD (1,227.79 kL/d). In 2002 it was diagnosed communication between the tubing string and the 9-5/8″casing at a depth of 55 feet (16.76 m). Preliminary studies carried out on tubing indicated the presence of a mechanism of sulfide stress corrosion cracking, due to the operational conditions registered at the well since 1999, where increases were reported in water cut and H2S concentration.
During the process of rehabilitation RA/RC, the reported section of tubing was recovered and a microstructural evaluation was done through electron and optical microscopy. It was determined that the failure mechanism attributed to the localized loss of mechanical properties of tubing, was due to cracking of material because of sulfide stress corrosion cracking.
This paper describes the failure analysis carried out on the tubing section recovered from well FUL-19L, as well as the recommendations set out for the selection of materials that guarantee mechanical integrity of tubing, in order to optimize the completion design for wells under sour conditions, and lower cost associated with work over.
