1. A system for analyzing an oilfield having at least one wellsite, each at least one wellsite having a wellbore penetrating a subterranean formation for extracting fluid from an underground reservoir therein, comprising: a data collection means for obtaining source data having a plurality of data elements of heterogeneous data types; a processor; memory for storing the obtained source data; a cache for temporarily storing data elements; functional method instructions stored on a computer readable storage medium configured for execution by the processor to perform a function on a dataset of a dataset type to obtain a processed dataset wherein a cache mode variable determines whether execution of the functional method instructions by the processor performs the function on data elements of the dataset temporarily stored in the cache; and client code instructions stored on a computer readable storage medium configured for execution by the processor to process a dataset, the client code instructions comprising: object instantiation code instructions configured to use dataset wrapper class instructions stored on a computer readable storage medium for execution by the processor to create the dataset with a dataset type from the obtained source data stored in the memory wherein the dataset wrapper class instructions comprise the cache mode variable that indicates whether data elements of at least a portion of the dataset are temporarily stored in the cache; and functional method invocation code instructions configured to call the functional method instructions with the dataset.