Groundwater is an essential resource for agricultural, municipal, industrial, stock and domestic use. Careful management of groundwater resources is essential to optimising the quality of social, environmental and economic life.
Most groundwater is stored within porous strata, referred to as aquifers. Development and production of unconventional hydrocarbon resources can potentially interfere with those aquifers and threaten local quality of life.
Qteq’s AquiSample downhole sampling system employs a low-flow, shallow-set micropurge bladder pump that is uniquely adapted to extract water samples from aquifers situated at any substantially greater depth.
The ability to greatly extend sampling depth beyond the 300m maximum rated pump intake depth is accomplished through connection of an extended ‘snorkel’ – consisting of a drop tube with remote fluid intake – to the pump fluid intake port.
This innovation completely removes the need to impose an upper limit on sampling depth, with only sampling time being impacted by location of the remote fluid intake.
Furthermore, a novel deployment and suspension system has been developed that enables the micropurge pump to be set at the desired location in the borehole, using a rig-less deployment technique.
The use of a bladder pump suspended in the borehole also eliminates the need for any form of subsequent borehole intervention to capture water samples.
The combination of rig-less deployment and intervention-less sampling therefore greatly reduces operational expenditure associated with use of the (AquiSample) technology platform.
AquiSample systems make use of the same innovative umbilical deployment architecture developed for its ResTraq suspended downhole pressure monitoring systems, with the bottom end of the snorkel terminated inside a weighted toolstring.
Special strain relief adapters are incorporated at both ends of the snorkel and at the top of the bladder pump to ensure the nitrogen and sample control lines are properly secured at all terminations.
The dual nitrogen and sampling control line umbilical is reeled off a single spooling unit through a temporary PCE system placed above a special design wellhead adaptor.
Once the AquiSample is at the desired setting depth, the temporary PCE is removed and the dual-control line umbilical cut and anchored using a BOP split clamp arrangement inside the wellhead adapter. The umbilical is then routed through ports in a Bowen tree cap that is screwed onto the wellhead adapter to maintain complete well pressure integrity.
Should the bladder pump size need to be changed, or even upgraded, the AquiSample system can be retrieved using the same spooling unit and temporary PCE system.