An apparatus and method is given for evaluating a well fluid sub-sample at the well surface as the sample is transported to the well surface from a downhole wellbore location. The invention collects a formation fluid sample under pressure. The fluid sample is further pressurized with a traveling piston powered by the hydrostatic wellbore pressure. The pressurized formation fluid sample is contained under high pressure within a fixed volume chamber for retrieval to the well surface. Multiple collection tanks can be lowered into the wellbore during the same run to sample different zones with minimal rig time. A pair of valves in series along the supply/discharge conduit respective to each tank accommodates extraction of a field sample to verify the sample integrity while still on location. The tanks can be emptied at the well surface with an evacuation pressure so that the fluid sample pressure is maintained above a selected pressure at all times or transported to an analytical laboratory.
Some embodiments of the present invention are related to devices and methods for sampling groundwater at multiple target depths, wherein each of the devices for sampling groundwater at multiple target depths comprises: a hammer part having a spring for generating inertia and a hammer connected to the spring; a sampling needle part having a needle integral with a impacting part impacted with the hammer; a guiding part for moving the sampling needle part in straight and downward direction; and a sampled water containing part having a sampled water container for collecting the sampled water through the needle.
Parameters of a pore-scale geometric model of a clastic earth formation are adjusted so that the output of the model matches measurements made one a core sample. Additional properties of the earth formation are predicted using the pore-scale model. The additional properties may be based on additional measurements of properties of a fluid in the formation.
Parameters of a pore-scale geometric model of a clastic earth formation are adjusted so that the output of the model matches measurements made on a core sample. Additional properties of the earth formation are predicted using the pore-scale model. The additional properties may be based on additional measurements of properties of a fluid in the formation.
A downhole connate water sample drawn from the formation surrounding a well is validated when mud filtrate concentration is acceptably low. A preferred method includes drilling the well with a water-based drilling fluid, or more generally a water-based mud (WBM), containing a water-soluble dye. The dye acts as a tracer to distinguish connate water from WBM filtrate in a downhole sample of formation fluid contaminated by mud filtrate from the water-based mud. Preferably, an optical analyzer in a sampling tool measures light transmitted through the downhole sample to produce optical density data indicative of dye concentration. Preferably, optical density is measured at a first wavelength to obtain a first optical density, and at a second wavelength, close in wavelength to the first wavelength, to obtain a second optical density. First and second optical density data are transmitted to the surface. At the surface, in a data processor, the second optical density is subtracted from the first optical density to produce a third optical density that is substantially free of scattering error. The data processor validates each sample that has an acceptably low third optical density. The invention also provides a method of determining when to collect a sample of downhole fluid drawn over a period of time from a formation surrounding a well.
The grain size of a pore-scale geometric model of a clastic earth formation are adjusted so that the NMR relaxation time distribution output of the model matches a measured NMR distribution. Fluid drainage and imbibing can be simulated. Additional properties of the earth formation are predicted using the pore-scale model. The additional properties may be based on additional measurements of properties of a fluid in the formation.
