The objective of this paper is to present an uncommon challenge of formation solids production from open-hole section while testing and completing deep HPHT carbonate formations and successful application of coiled tubing technique for effective wellbore cleanouts to rediscover the exploratory well.
A discovery of oil and gas from a new field was lost because of well complications during well completion operation. Re-entry was made in the existing exploratory well to reactivate the discovered zone since the zone of interest could not be cased due to drilling complications and completed the well in 3-7/8" open-hole section for production purposes. Open-hole completions are difficult to manage due to the various stabilizing and destabilizing factors. While tubing check by slick line it has been found that the well was filled with sludge/solids up to the kick of point (15,830 ft). Deeper, deviated and open-hole well presents challenging task of carrying out interventions to unlock the reservoir potential. Cleaning of rock solids in the open-hole section in this deviated well is more challenging and critical which requires new methodology in order to achieve effective well bore cleaning.
Carbonate formation solids production is different from the common problem of sand production from the unconsolidated sandstone reservoirs. As there is possibility of solid production from the open-hole section, a methodology for cleaning of solid fill in open-hole section using 1-1/5 inch coiled tubing with modified jetting tool was applied. While circulating 1.5 ppg brine to clean out fill, the well became active.
The uncommon problem of formation solid production was managed well within the available resources. Mechanical restriction in a highly deviated and open-hole section was cleared successfully by using coiled tubing intervention to improve efficiency, reduce cost, reduce operating time and allow early production. The lost discovery was rediscovered by overcoming all challenges. During production phase it was observed that the solid plugging in production tubing is occurring frequently in this case study well. The solid production problem faced during testing was re-evaluated and the risks are properly addressed in future well test procedure.
This paper addresses the relevant testing, completion, solid cleaning and production issues and discusses the solutions arrived at. This paper also details the application of CT in open-hole well bore cleaning, post cleaning well performance, and lessons learned. The best practice applied in this discovery well will be useful for the future exploratory/delineation wells planned to be drilled in similar reservoir.