The oil and gas industry has developed various tools capable of determining formation fluid properties. For example, borehole fluid sampling and testing tools such as Schlumberger's Modular Formation Dynamics Testing (MDT) Tool can provide important information on the type and properties of reservoir fluids in addition to providing measurements of reservoir pressure, permeability, and mobility. These tools may perform measurements of the fluid properties downhole, using sensor modules on board the tools. These tools can also withdraw fluid samples from the reservoir that can be collected in bottles and brought to the surface for analysis. The collected samples are routinely sent to fluid properties laboratories for analysis of physical properties that include, among other things, oil viscosity, gas-oil ratio, mass density or API gravity, molecular composition, H2S, asphaltenes, resins, and various other impurity concentrations.
The reservoir fluid may break phase in the reservoir itself during production. For example, one zone of the reservoir may contain oil with dissolved gas. During production, the reservoir pressure may drop to the extent that the bubble point pressure is reached, allowing gas to emerge from the oil, causing production concerns. Knowledge of this bubble point pressure may be helpful when designing production strategies.
Characterizing a fluid in a laboratory utilizes an arsenal of devices, procedures, trained personnel, and laboratory space. Successfully characterizing a fluid in a wellbore uses methods, apparatus, and systems configured to perform similarly with less space and personal attention and to survive in conditions that quickly destroy traditional lab equipment. Identifying the undesired phase change properties of a fluid is especially useful when managing a hydrocarbon reservoir.