Valhall – Pushing the Limits for Openhole Zonal Isolation — Qualification and Field Trial of 10,000-psi Oil-Swelling Packers

Abstract

TX 75083-3836, U.S.A., fax 01-972-952-9435.Abstract BP-Norge AS operates the Valhall Field in Norway and relies on multi-zone water injection for reservoir management and control of unwanted water production for Valhall wells. A produced water shutoff method in this field is necessary, and equipment must be capable of maintaining integrity at differential pressures of 10,000 psi during prop-fracture stimulation of the individual zones in the oil-producing wells. The operator wanted to find a new completions solution that would enable long horizontal reservoir sections to be completed and stimulated with the capability to shut-off unwanted water at a later time during well life.Swellable elastomer packers (SEPs) were suggested to the operator as a possible method for zonal isolation. Unfortunately, three attempts to qualify the currently available SEPs to the 10,000-psi differential pressure (DP) for Valhall were all unsuccessful; therefore, the decision was made to try a new design that used an innovative mechanical end-ring system. This configuration uses a solids-laden oil-based mud (OBM) to expand the element installed on the outer surface of the basepipe that forms part of the reservoir liner. This eliminated the need to spot dedicated swelling fluid.The changed configuration represented a significant step change in the design methodology of SEPs. The new design not only enabled the reduction of element length and packer OD, but it also could withstand the high DP ratings as well as increased the DP ratings of long SEPs. The new configuration required qualification testing, and this paper presents the case history of the operator's full-scale qualification testing up to 10,000 psi across two 5-meter packers as well as the improvements the new SEPs could offer over previously used equipment and methods.The paper will also discuss the design, other potential applications, and the advantages of the new SEP design. A case history of the first installations of the new SEP worldwide will be presented as well.

Evaluation on the Seal Performance of SMP-Based Packers in Oil Wells

“…The seal performance after setting is directly related to the effects of fracturing or other production operations [ 21 ]. A series of studies was conducted on conventional mechanical packers [ 22 , 23 , 24 , 25 ]. The majority of studies focused on the mechanical properties of the sealing element, that is, the elastomer [ 26 , 27 , 28 ].…”