Increasing Solid Expandable Tubular Technology Reliability in a Myriad of Downhole Environments

Abstract

Abstract Since the spectacular arrival of solid expandable tubulars four years ago, customers have embraced this technology as a revolutionary well constructionand production solution. Through innovative technical development and equipmentreliability, solid expandable tubulars continue to grow in acceptance anduse. Solid expandable tubulars have been used successfully to reach requiredtotal depth (TD) with adequate completion size, slim the well constructionprocess, and overcome abnormal pressures encountered down hole while drilling. In addition, this technology has been used to rejuvenate wellbores for welldeepening, casing reinforcement for stimulation, as a solution for corrosionproblems, and to cover leaks and perforations. As a result, the overall cost ofdrilling and production operations has been reduced. This expansion process requires the successful integration of the followingconditions and equipment:casing capable of surviving in-situ reformingfriction reduction between the expansion cone and the casingexpandable flush joint connectioncontainment of hydraulic pressures during the entire expansion processsurviving expansion in downhole environment During the last four years, solid expandable tubulars have been installed inmore than 113 wells. Reliability has improved from an average of 67% in 2000, to 83% in 2001, to over 95% in 2002. In the past, the reliability of solidexpandable tubulars has been measured by a limited set of criteria for jobsuccess. The reliability definition should be expanded to include otherperspectives of the total system. This paper will discuss actual downhole conditions, including well control, lost circulation, and high temperature/high mud weight, in which solidexpandable tubulars were used as a successful solution. This paper will alsodiscuss additional measurement perspectives with the goal of creating a 100%reliable technology. Origins of Solid Expandable Tubular Technology The idea for solid expandable tubular technology was born out of age-oldtechnology; that being cold-working steel. Since man first discovered fire, metal has been stretched, pulled, and twisted into specific shapes. Adaptingthat principle to downhole drilling conditions gave rise to a revolutionarywell construction process. The underlying concept of expandable casing is cold-drawing steel tubularsto the required size. The cold drawing process denotes shaping steel to aspecific shape as opposed to cold-working steel to an unintentional shape. An expansion cone moves through the tubular by differential hydraulicpressure and/or by a direct mechanical force to permanently deform the pipe(Fig. 1). The differential pressure is pumped through an inner-stringconnected to the cone, and the mechanical force is applied by either raising orlowering the inner-string. The cone expands the tubular past the elastic regioninto the plastic region but short of ultimate yield (Fig. 2). Since the first installation in 1999, solid expandable tubulars haveprovided alternatives in drilling, completion, and workover operations byenabling operators to access zones that were previously unreachable and toincrease initial completion size. Expandable tubulars have been used to extendproduction life through the remediation of existing pay zones and to accessnew, potentially productive formations. Being able to expand solid tubulars downhole reduces the tapering effectthat occurs when using multiple casing strings in deepwater drilling. Theseexpandable systems conserve valuable hole size. Conserving hole size, ordiametric efficiency (DE), allows additional pipe strings to be deployed todrill deeper or farther. Controlling the DE also allows target zones to beproduced through larger diameter production tubulars.