jws01us posted on 2/18/2010
Degradable acid stimulation
The MaxCO3 Acid degradable diversion system released in Doha recently by Schlumberger is a polymerfree, non-damaging acidising method suited for oil or gas well matrix and fracture stimulation in carbonate reservoirs with permeability contrasts or natural fractures in open-hole and cased-hole intervals, regardless of deviation.
Schlumberger reports that global MaxCO3 treatments, their design, execution and evaluation optimised with proprietary software, have frequently achieved productivity increases in excess of 100%. Treatment volumes were reduced by up to 50%, resulting in shorter well cleanup times and less flaring. Moreover, less rig time is utilised since there is no requirement for multiple operations traditionally needed to perforate and stimulate zones individually.
As an example, the MaxCO3 Acid treatment has been successfully applied in Khuff Formation carbonate in Qatar’s offshore North Field where wells drilled in this thick, heterogenic reservoir are susceptible to large variations in transmissibility. MaxCO3 Acid treatments can be bullheaded or pumped through coiled tubing, batchmixed for small volume jobs or mixed on the fly for larger treatments, continuing to stimulate as they degrade.
Innovative AUV maps WA
Fugro Survey and Hafmynd Ehf in joint initiative with Woodside Energy have successfully run customer acceptance trials of a Gavia autonomous underwater vehicle (AUV) down to a subsea depth of 1000m offshore Western Australia, well surpassing the former 220m benchmark, also achieved by a Gavia vehicle.
Small and portable, the Gavia AUV is manufactured in Iceland by Hafmynd in a modular configuration enabling inclusion of various payloads such as an inertial navigation system (INS), GeoSwath bathymetric sonar and additional batteries.
The model in service with Woodside is optimised for offshore surveying, fitted with an underwater camera, sidescan sonar, multibeam echosounder, high accuracy INS, and navigation software to automatically track seabed pipeline.
In the trial, the Gavia AUV was set to run a grid of survey lines at 12m above the seabed, recording both sidescan sonar and swath bathymetric data, followed by a seabed habitat photo survey line run at 2m above seabed. Dive time from surface to 1000m was approximately 30 minutes.
Woodside anticipates using the vehicle primarily for pipeline inspection, as well as surveys for nearshore environment, debris in restricted areas, and deepwater assessment of flowlines and other seabed infrastructure. The AUV will be utilised from vessels of opportunity and made available for third party projects.
Hyperbaric rescue
Singapore-based rescue vessel and launching equipment developer Vanguard Offshore is introducing a line of self propelled hyperbaric lifeboats (SPHL) to help ensure the safety of divers working in fully saturated environments. The lifeboat, manufactured under ABS regulations, will be available in 2010 to meet the needs of the global diving community in view of recent significant changes in hyperbaric rescue craft classification specifications.
The Vanguard SPHL includes all ancillary equipment, engine, generator, crew facilities and life-support system for an independent survival capability of 72 hours, and davit launching equipment.
The vessel is constructed of hand-laminated GRP (glass reinforced plastic), with a totally enclosed superstructure and elevated steering tower aft. Buoyancy is achieved through integrated longitudinal tanks filled with polyurethane foam, augmented by additional upper buoyancy for hull selfrighting.
EM casing inspection
Schlumberger’s newly released electromagnetic EM Pipe Scanner casing inspection tool combines a slim mandrel with 18 pad sensors that can run through tubing to produce a quantitative scan of the interior surface and thickness of production casing. The tool can also be used to locate generalised tubing corrosion, grooves and splits.
The tool makes a highspeed reconnaissance run as it descends into the well, identifying places of interest followed by diagnostic scans as it ascends to produce images that determine the severity and nature of the corrosion.
In time-lapse mode, the EM Pipe Scanner is designed to provide corrosion rate estimates, find casing corrosion behind tubing and determine inner tubular radius behind scale.
The slim 21/8in diameter tool can easily pass below the tubing shoe to quantify metal loss in percentage and average inner diameter (ID) of casing ranging from 27/8in to 95/8in OD. In double casing strings, a continuous log of average casing ID and total metal thickness is recorded.
Schlumberger reports it has successfully completed more than 100 jobs in 11 countries, deploying the fluid insensitive scanner by wireline, tractor and coiled tubing in well deviations up to 90°. AOG