Subsidence-Induced Casing Dogleg (SICDog) Remediation With an Innovative Hybrid Milling System

摘要

Subsidence Induced Casing Doglegs (SICDogs)rnoccur in many oil reservoirs worldwide. Doglegging, at arnminimum, leads to reduced mean time between failures of rodrnpumped wells. SICDog remediation techniques in the pastrnhave had limited success and are relatively expensivernprocedures. Most of these techniques have used variousrnrotating mill assemblies and different strengths, sizes andrnconnections of drill pipe. Some techniques have been extreme,rnsuch as destroying the dogleg with explosives. A multiphase,rnrisk-sharing, team effort over four years between Aera EnergyrnLLC and Weatherford International Ltd led to therndevelopment by Weatherford of a hybrid broaching/millingrntool. This hybrid milling system reliably and quicklyrnremediates multiple doglegs in a single well bore. SevenrnDiatomite reservoir producers in the South Belridge Oil Field,rnKern County, California were repaired and successfullyrnreturned to production in the latest four well phase. The workrnwas routine in nature, requiring no special or extraordinaryrnservices. In this paper, we will discuss the geometry ofrnSICDogs and the challenges they pose to rotational milling.rnOther topics will include the evolution of the hybrid tool fromrnexperiences in this and other projects, operational concernsrnsuch as well control and repair options of the remediatedrnSICDog. Lessons learned during the evolution of thisrntechnique will be discussed at length.