US Patent 7644610 Automated formation fluid clean-up to sampling switchover

Apparatus and method for downhole formation fluid sampling include conveying a carrier into a well borehole that traverses a subterranean formation of interest, the carrier having a port and placing the port in fluid communication with the subterranean formation of interest. The method includes urging a fluid into the port using a fluid control device, the fluid containing a formation fluid and a contaminant, generating a first signal indicative of a first fluid characteristic of the fluid using a first test device in communication with the fluid, and generating a second signal indicative of a second fluid characteristic of the fluid using a second test device in communication with the fluid. The first signal and the second signal are processed using a processing device to estimate a level of contamination in the fluid, and a control signal is generated when the estimated level of contamination meets a predetermined value, the control signal actuating the fluid control device to direct fluid having a level of contamination at about or below the predetermined value to a fluid sampling chamber carried by the carrier.