Successful Liner Application Using Foamed Cementing Technology for Low-Pressure, Naturally Fractured Formations

摘要

This case history includes the design, testing, job execution, andrnpost-job results of a successful foamed spacer/cement applica-tion.rnDuring this application, a liner was cemented across arnproductive formation in which a significant amount of low-densityrnmud was lost during the drilling phase.rnDuring a deep-well drilling campaign in Argentina, a natu-rallyrnfractured formation located between 3828 m and 4290 mrnexperienced severe lost circulation. Once this section was drilled,rna single-stage cement slurry needed to be placed without majorrncement slurry losses to the formation. The section then needed tornbe successfully sealed from the shoe to the top of the liner.rnAdditional consideration was given to minimizing fluid-lossrndamage to a potentially productive zone that consisted of low-pressurernmicrofractures and large fractures.rnOne of the most difficult challenges in a cementing operationrnis getting successful cementing results across low-pressure for-mationsrnthat have lost-circulation tendencies. Although alterna-tivernmethods involving stage tools and top squeezes can bernconsidered, liner applications tend to complicate the operationalrnphase because of liner hangers, tool outside-diameter (OD)rngeometries, plugs, and pressure-activation requirements. Anrnadditional challenge was to effectively remove the residual mudrnfilter cake from the annulus of a 15° uncentralized casing in arndeviated wellbore.rnAfter all potential challenges to this liner application werernaddressed, a foamed cement/spacer system was determined to bernthe best solution for meeting all objectives and completing thernliner application. This lightweight cementing system possessesrnmany benefits, including (1) superior mud displacement,rn(2) high strength, (3) low density that can be adjusted onsite,rn(4) ductility for preventing stress cracking during the casingrnpressure test/drilling phase, and (5) the capability to prevent gasrnmigration from the major fracture network of the productivernformation.