heating or a combination of both in the example the heat source 441 is a microwave source incorporated into the outer probe it is advantageous to also monitor the pressure profile during the operation for example through an solid state or mems type pressure sensor not shown co located with the temperature sensor 452 to record a complete profile of the sampling procedure after being heated and guided into the sampling tool the sampled fluid is analyzed and either rejected or pumped into a sampling chamber following the procedures described referring to fig2 above during the sampling process the controlled heating is continued until the sample has mobility such that it can be collected the rise in temperature of the fluids in the formation is monitored using the temperature sensor 452 when the sensor indicates that the desired temperature has been reach the sample is removed using the guarded probe 461 462 the inner probe 462 is heated to ensure continual flow of fluids during the extraction procedure this aspect of flow assurance is important to ensure the sample is taken in good time and is representative of the fluids in the reservoir the desired temperature may be set using formation evaluation performed prior to the sampling typically the formation evaluation used is the result of a wireline logging operation the viscosity of the in situ oil can be for example determined via correlation to the t 2 relaxation time gained through nmr logging with such prior knowledge the required temperature or its maximum can be determined using for example a database of experimental data such as illustrated in fig1 5 and 6.