Defining Testing

Well and formation tests, which entail taking measurements while flowing fluids from the reservoir, are conducted at all stages in the life of energy fields, from exploration through development, production, and injection. Operators perform these tests to determine whether a formation will produce, or continue to produce, hydrocarbons at a rate that gives a reasonable return on further investments. Operators also use test data to determine the limits of the reservoir and to plan the most efficient production methods.

During testing, operators measure formation pressure, characterize the formation, and determine permeability and skin—damage to the formation incurred during drilling or other well operations. Data that indicate how the formation reacts to increases and decreases in pressure during a test can also reveal critical information about the reservoir.

Well and formation tests are also primary sources of critical data for reservoir models and are the principal means by which engineers confirm or adjust reservoir model parameters. Engineers use these models to understand how reservoir fluids, the formation, and the well interact and use that knowledge to optimize completion and development strategies.

Operators assess the production potential of wells through several test methods, singularly or in combination. They may choose to perform a production well test in which the well is flowed through a temporary completion to a test separator. Or they may use a wireline formation tester to capture fluid samples and measure pressure downhole at the zone of interest. Engineers sometimes perform both types of tests.