The Sumandak field is located offshore Sabah, northwest of Labuan Island, in Malaysia. The majority of the reservoirs in this field are oil producers subject to sand production at some point during well life.
The subject well was completed using a typical completion design for the current field, running standalone screens inside an 8.5-in. open hole using 3.5-in. dual and monobore production tubing strings. Several wells in the study field are shut in and not producing because of the significant amount of sand and fines produced to surface facilities and filling the tubing, thus negatively affecting production. To reactivate the wells, remedial sand control techniques were necessary to restore productivity of the reservoir.
This paper presents a through-tubing recompletion method combining mechanical techniques, such as a through-tubing intervention approach, along with downhole equipment and a chemical approach that used a fines control treatment, which helped bond the formation fines in place to assist with restoring initial cementation of the reservoir and reduced the risk of blocking the screen media.
The success of this operation was aided by an intensive laboratory study of cores from the field to optimize the design of the tool assembly and treatment formulation based on the particle size distribution (PSD) profile and production histories from the described wells.
Through-tubing downhole tools were chosen considering tubing and casing sizes, the wellbore minimum restriction, type and locations of the landing nipples, reservoir properties, bottomhole pressures, packer setting depth, length of the reservoir to be recompleted, location of the interval in relation to production tubing, length of the rat hole below the interval, and consideration to repair an existing but possibly damaged standalone screen. An advanced wellbore-cleanout technique for low bottomhole pressure reservoirs that uses an upper jet and washdown jet nozzles in conjunction with coiled tubing (CT) was performed before the consolidation treatment.
This is the first time a through tubing recompletion of the existing wellbores has been implemented in the Sumandak field in offshore Malaysia. This methodology has integrated new and existing technologies to achieve successful sand control operations to bring a well back on production after having been shut in because of sand production. It helped reactivate the wells and improve the recovery reserve rate of the field.
After this successful treatment, productivity of the well has exceeded expectations compared to conventional gravel packed wells. Such placement techniques created many opportunities to effectively and economically treat and revive wells experiencing similar production issues.