A Recent Gulf of Mexico Cavity Completion

Abstract

Summary Production was dramatically improved by cavitating (i.e., intentionally producing sand) an offshore gas well on the Gulf of Mexico shelf. The cavity completion was conducted over a period of 10 days and involved producing the well with temporary equipment to safely produce, collect, and dispose of the produced sand. No hydrocarbon emissions resulted because production could be routed back through the permanent facilities. Following the operations, the well was returned to flow through the permanent facilities at a much higher producing rate, with much lower sand production. Before the cavity-completion operations, the well had been choked back to a low gas rate (<1 MMscf/D) because of sand production. The low gas rate was insufficient to continuously lift liquids, causing the well to become liquid loaded and/or slug. The well was evaluated for a sand-control completion, but this type of repair was believed to entail too much economic risk because of significant reservoir unknowns. Further evaluation suggested that the well had the attributes for successful cavity completion. This paper discusses the cavity-completion evaluation process employed and the operational results and learnings; a similar process may be applicable to other wells. Introduction A cavity-like completion has been used in other areas to attempt to reduce the amount of solids produced and improve the productivity of wells.1 For this offshore-well application, a cavity-like completion was believed to provide a viable option once it was determined that the well produced too many solids as originally completed. A conventional repair to install a sand-control completion was evaluated but was believed to entail too much economic risk. While there were significant reservoir unknowns, a cavity-type completion could be attempted at a relatively low cost. Following the cavity completion, the well was returned to production at a higher rate (four-to five-fold increase), with minor amounts of sand production, until the reservoir watered out. A cavity-like completion involves purposely producing sand with the intention of creating an enlarged void or enhanced-permeability area around the wellbore. Sand production can entail risks (discussed below), so this method may not be appropriate in other situations.