Deep Gas-Well Cementation: A Review of Risks and Design Basis for Use of a LiquidCement Premix for Large Offshore Cementing Operations

摘要

Large volume offshore cement jobs can present a number ofchallenges. Larger casing strings set to deeper depths havedriven up the volume of cement jobs beyond the capacity ofmany rigs. A recent well design called for two cement jobsthat would exceed 2,400 bbl. There were a number of optionsconsidered for dealing with these large cement jobs. Theseincluded spotting lift boats beside the rig, the use of adedicated cementing vessel, the deployment of ocean goingbarges, spotting an additional jack up rig, or the use of a liquidcement premix.This paper discusses the risk analysis anddevelopment plan that led to the selection of a liquid cementpremix for the large volume jobs. The paper covers the designrequirements of the jobs and addresses the risks associatedwith the available options. Information is provided on risksassociated with boat and barge stability, draft limits atavailable bulk facilities, deck load limits and logistics ofalternative designs. Rig based pumping operations areincluded with respect to logistics and timing issues related toplacing the entire operation on the rig.These jobs were to be the largest liquid cementpremix jobs to date. Slurry stability and consistency weremajor concerns on these jobs. These were addressed throughfull scale testing on the vessel. (The results of which aresummarized in SPE 98894 1.) The paper further covers theequipment requirements and mixing needs and compares theselected option to that of a conventional cement job.