The first step in any biostratigraphic correlation is to obtain a sample. In this field, samples primarily come in the form of cores obtained during drilling for petroleum or from deep sea drilling programs. The cost of obtaining each core sample runs upwards of10 million dollars. Because of the associated costs of retreiving samples, any potential source of error must be eliminated prior to drilling.


The locations of the first wells are determined by evaluating geophysical data and by studying any previous info related to your area of exploration. Subsequent wells locations are evaluated depending on the data obtained in the first core.