Effective reservoir management and production can maximize the recovery of hydrocarbons originally in place in the reservoir. The development of proper management strategies requires accurate knowledge of the fluid and rock properties. Recommended sampling techniques will be presented in this section which will permit collection of quality samples of the reservoir fluid which will allow the laboratory to provide accurate and applicable data to the client.
The major objective of the sampling program is to collect samples that are truly representative of the reservoir fluid in place at the time of sampling. If the procedures are incorrect or the samples are taken from an incorrectly conditioned well then the samples will not be representative of the reservoir fluid. Non-representative samples will not exhibit the same properties as the reservoir fluid and the use of fluid data derived from these samples will lead to erroneous reservoir management, however accurate the laboratory analysis is. Incomplete sampling and reservoir data can also make it difficult for the laboratory to correctly perform the required analyses.
Methods for collecting samples of reservoir fluids fall into two major categories “subsurface, down-hole or bottom-hole sampling” and “surface or separator sampling”, which are indicative of the location of the sampling point from which the sample is taken. Various factors influence the selection of the type of sample to be collected, including type of reservoir fluid, relative expense of the method and equipment availability.
The choice of sampling method for a particular well cannot be considered as a routine matter as each well usually presents different constraints on equipment, time or cost. The details of a given sampling method or procedure often require some modification to overcome unforeseen problems and these must be made on the spot by experienced personnel.