Patent ID: 7992430
Filing Date: 2011-08-09
Classification: E21B,G01N

Abstract:
1. A method for determining chemical or biological properties of a liquid, comprising: situating a sampling device having a fluid-filled cavity at a subsurface position below an upper surface of the liquid, the fluid having a density lower than the liquid, allowing a flow of the liquid through a cartridge containing a material that interacts with components of the liquid and into an inlet opening of the sampling device, said inlet opening is provided with a backpressure regulating device so as to regulate a liquid inflow rate into the cavity for a sampling period, said backpressure regulating device comprises a capillary tubing having an internal diameter of 10-500 μm simultaneously allowing a flow of the fluid out from the cavity through an outlet opening of the sampling device, removing the sampling device from the subsurface position for subsequent analysis for determining said chemical or biological properties of the liquid, wherein the inlet opening of the sampling device is connected to a liquid conduit having its outlet inside the cavity and above a bottom of the cavity, so that the free surface of the liquid inside the cavity, during most of the sampling period is below the liquid conduit outlet, for the hydrostatic pressure driving the flow of the liquid into the cavity to be substantially constant during most of the sampling period.