The wellsite handling of unconsolidated core is a risky process that might hamper core integrity if inappropriate procedures are utilized. ALS has developed specialist techniques and equipment for core stabilization of unconsolidated formations utilizing dry ice stabilization.
Freezing techniques have been subject to numerous studies over the last decade, demonstrating that repeated freezing and thawing is a main contributor to core damage. Despite recent improvements in the freezing procedures, no proper solution has been found to address the problem of unwanted freezing/thawing cycles during transportation. The ALS Lithofreeze™ technique guarantees maintained, constant, core freezing thus offering a perfect long-term stabilisation.
- Core pre-conditioning using a full length core basket (20 or 30 ft) with multi-channel sensors.
- Careful monitoring of temperatures during the freezing cycle and full audit of the first critical stage of the freezing process.
Spanning a vast range of international locations, ALS’ Lithofreeze™ technology has been successfully tried, tested and further developed over the last decade. With offset records in Brunei, Brazil, North Sea, Angola, Equatorial Guinea and Nigeria, ALS is considered a leading provider of core freezing services.
Freezing containers – Frost Box
ALS provides specially designed containers, Frost Box containers that monitor temperatures from the moment the core enters the freezing cycle.
Monitoring of the frost box conditions provides a full audit trial of the freezing cycle. The Frost box will record:
- Internal temperature at the top, middle and bottom of the box.
- Ambience temperature outside the box.
- 3-dimensional acceleration (shock).
- Any opening of the box and duration thereof.
Climate Controlled Shipping Container
One of the largest issues when utilizing dry ice for stabilization is insuring that core remains frozen throughout the entire transportation lifecycle. ALS has developed equipment specifically to address this issues in its Climate Controlled Shipping Containers. These units are able to maintain a set temperature from -40c to +40 C through the use built in refrigeration units. They are dual power, both diesel and electric, allowing core to be maintained during transportation, even if these means shipping via ocean freight from remote locations.
The location and temperature of the units can be monitored remotely via a live web portal that the client has access to at all times. Through this portable clients can not only monitor temperature and location they can change the set point temperatures remotely, export temperature logs to excel format and even export GPS data to Google Earth.
These units are ISO certified for international sea freight, DNV certified for offshore use and have the capability to transport over 2000 feet of core in one unit
Dry Ice Pelletizer
Another logistical challenge with dry ice stabilization is sourcing in remote locations. Most projects require large amounts of dry ice to be sourced, sometimes tons, in order to properly freeze the core. In remote locations this can not only be challenging but costly. ALS has developed a system to manufacture the dry ice either at an offsite location or directly at the rig, eliminating transportations costs, logistically challenges and reducing the total amount of dry ice needed for a project by reducing the need to account for the sublimation of the dry ice on location.In remote locations where dry ice is not easily obtainable, ALS can mobilize its pelletizer equipment and CO2 tanks to produce dry ice directly at the wellsite.
This technique is used to chill fluids inside the rock sample and limit their migration during transportation, aiding subsequent analysis at the laboratory. Used in conjunction with Lithotarge® injection on cores with limited consolidation, this technique also benefits core stabilisation.
- Limit fluid migration
- Preservation of unconsolidated core
- Controlled process – high quality eutectic plates