Openhole Horizontal Completions in Niger Delta

摘要

The Niger Delta is a highly activity region in open holernapplications. A wide variety of completion types have beenrndeployed in open hole in the region. A major challenge inrnthese completions is to deliver quality wells through thernchoice of an optimal sand control system. A locally developedrndatabase tracks the performance of the sand face completions,rntheir reliability, observed failures and their causes. The oilrnreservoirs have used barefoot, standalone screens, slottedrnliners, gravel packs and expandables while pre-drilled linersrnhave been used for borehole support. The expandablerntechnology is relatively the most recent technique but of thernthree hundred and forty run so far globally as at Septemberrn2005, more than 3/4 has been deployed in Niger Delta alone.rnFor the non-associated gas reservoirs, most of which havernbeen conventional wells, based on fair understanding of thernrisks and uncertainties associated with two main sand controlrnoptions namely, gravel packing and the expandable sandrnscreens, work has been done to show adequate demonstrationrnof the process of selection. This structured approach considersrndesign options based on several factors such as possiblernproblem with under-reaming relatively deep section, previousrnperformance in the existing high rate gas wells, productivityrnand better life cycle design perspectives. Within the Darcyrnpermeability regime of the sandstone gas reservoirs,rnproductivity with respect to horizontal versus conventionalrncompletion was compared and a matrix capturing the risksrnimpact of a horizontal completion is attempted.rnThe work concludes by suggesting future concerns in openrnhole horizontal sand control to include cost of installationrnfailure, accurate modelling upfront and remedial zonernisolation after gas/water breakthough.