Saudi Aramco Skip & Ship Operations in the Sensitive Manifa ...

EnviroNewsIssue Number 1926Saudi Aramco Skip&ShipOperations in theSensitive Manifa MarineEnvironmentTypical offshore jack-up rig.Scheduled to come on stream in 2014, the Manifa FieldIncrement is the largest single offshore oil developmentin the history of Saudi Aramco oil operations. Theshallow marine environment also is located in one ofthe Kingdom’s most sensitive aquatic breeding grounds,mandating the company to adopt a strict “zero discharge”policy in accordance with corporate environmental protectionstandards and guidelines as well as government regulations.Consequently, in drilling selected near-shore development wells,the company has been actively involved in evaluating innovativedrilling waste management technologies as an alternative toconventional operational practices, specifically for the collection,transfer and disposal of drill cuttings.After evaluating various waste management options, includingdetailed injectivity field testing and simulations for selectedgeologic zones, the Manifa Waste Management Team selectedsubsurface cuttings re-injection (CRI) as the most promising,cost-effective, and technically feasible approach to eliminateany accidental discharges to the marine environment duringnormal drilling operations. Skip&Ship was chosen for collectingThe shallow marine environment also is located in one ofthe Kingdom’s most sensitive aquatic breeding grounds,mandating the company to adopt a strict “zero discharge”policy in accordance with corporate environmentalprotection standards and guidelines as well as governmentregulations.

27Summer 2010and transferring cuttings onshore while drillingthe CRI wells as well as a contingency backup incase of equipment failure during injection.The primary objectives of the planned operationwere to eliminate any overboard dischargeswhile keeping rig downtime to a minimum.OperationFigure-1 is a schematic showing the Skip&Shipprocess, from the collection of cuttings at the riguntil the final disposal at a marl-lined waste pitonshore designed for the transfer and disposalof waterbase mud (WBM) cuttings.1) Load empty skip on forklift2) Transfer empty skip on truck3) Delivery to port vessel/rig/vessel4) Vessel full skip to transport truck5) Unload full skip6) Skip dumping at waste pitDisposal PlantFigure-2 shows the vacuum collection system(VCS) conveyance technology that is engineeredto collect, move, and store cuttings withina totally enclosed environment to minimizepotential spill, containment, and safety issuesinherent with “open” systems. Its versatilevacuum-fed rotary hopper allows for continuouscollection along with the nonstop discharge ortransfer of materials into open-top slurrificationunits, standard cuttings skips, sturdy lined bags,or cuttings dryers.For the Manifa project, the VCS functions asthe primary cuttings transportation packagefrom the shakers to the skip station. The systeminstalled aboard a jack-up rig includes dual100-hp vacuums fed by twin roto-hoppers tosupply the rig with a continuous vacuum. Twovacuums are required to handle the high rateof-penetration(ROP) in the upper hole sections.The VCS is able to fill four skips continuously,which minimizes downtime waiting for thecrane.Figure-1. Schematic of Skip&Ship operation.Figure-3 shows the skips being transferred bycrane from the rig to the supply boat. To avoiddown time and issues related to limited space onthe rig, it is important to monitor and schedulethe transfer of skips. Typically, a total of 30 to40 skips are transferred during one loadingoperation. Then, the supply boat transfersthe skips to the Tanajib facility for offloading(Figure-4). Subsequently, the skips are loadedon trucks for transfer and disposal at the nearbywaste pit (Figure-5 and -6).Figure-2. Vacuum collection system (VCS).Figure-3. Skip transfer to supply boat.Figure-4. Transfer of skips to Tanajib facility.

EnviroNewsIssue Number 1928Figure-5. Skip transfer to waste pit.Figure-6: Skip unloading at waste pit.Table-1 shows the estimated volumes by well hole size and required skips for a typical well. The totalvolume for the development well was approximately 2,700 tons, and more than 531 skips wererequired.Table-1. Cuttings volumes and skip requirements.Well Hole SizeSection Total Depth, ft (m)Section Volume (Tons)Skips Used27 in1,110 (338 )4047822 in4,797 (1462)1,51129516 in5,984 (1824)3085912 ¼ in8,408 (2563)328638 ½ in9,543 (2909)19136SafetySafety and environmental protection are alwaysthe primary concerns during any companyoperation. To date, despite severe weather andcontinually changing drilling conditions, theVCS system has been successful in collectingand transporting over 11,000 tons of cuttingsfrom five offshore wells for land-based disposal.More importantly, even though more than8,200 crane lifts were required to transfer 2,100skips, no safety incidents were recorded duringloading, offloading and transporting operations.Furthermore, the VCS system continues tooperate successfully on jack-up rigs, resultingin zero downtime during rig operations, withminimal maintenance required.SummaryThe VCS has been shown to be an excellentsystem for the safe, efficient transfer of largevolumes of WBM drilling waste during offshoredrilling operations. Also, Skip&Ship is being usedas a contingency backup during the ongoingManifa cuttings re-injection (CRI) project. Asthe Manifa Project expands, it will be importantto utilize proven waste management systems toprotect the sensitive marine environment, meetcompany standards and guidelines, and complywith stringent government regulations.AcknowledgementsWe would like to thank those individuals fromall the contractors that were involved alongwith Drilling & Workover Services Department(D&WOSD), Drilling Technical Department, andthe Environmental Protection Department whohave supported these successful operations.Submitted by Phil Gagnard and FalahAl-Herz (D&WOSD), Ahmed Baim(NAODD), Bruce Olson and ToddDugas (M-I Swaco).