While tripping the core to surface, gases escape from the core toward the annulus. Identifying these gases can be a valuable source of information in regards to safety and better characterization of the reservoir hydrocarbons.
Gas Trapper™ allows a rapid and safe assessment of eventual gas presence as well as to identify the composition of the gases themselves. The technology is made possible with ALS Thin Sleeve System (TSS) which employs a concentric, triple tube core barrel configuration. The escaping gas is channelled between the liner and the TSS inner tube. As the gas migrates toward the top of the barrel, a special trapping device collects the gas.
The gas collection chamber is created between an extended ball seat and the inner tube extension. This “gas chamber” has a capacity of several litres and any excess gas will escape via the ball seat as in a normal barrel configuration. When pulling the barrel out of the hole, a valve mechanism incorporated in the system will close the chamber when the hydrostatic pressure reaches two bars.
On surface, a special gas cylinder is connected to the top of the inner head and all trapped gas is safely recovered from the chamber and captured for analysis. A small sample can also be collected using a special syringe and the gas can be immediately analyzed from a nearby Chromatograph. H2S presence is the first concern. If identified, the core recovery procedure can be conducted with the appropriate safety equipment and procedures.
The gas cylinders are then shipped to a geochemical lab for further gas analysis. ALS provides these sealed containers as well as the management of the gas analysis in the absence of convenient laboratory facilities.