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GeoMark Research, Ltd.
9748 Whithorn Drive
Houston, Texas 77095
GeoMark Research, Ltd.
PVT Analyses
Overview
Today’s fast-paced market requires quick results and accurate data to make reliable hydrocarbon decisions in a timely manner. The GeoMark PVT Laboratory performs a full range of pressure-volume-temperature (PVT) studies, oil-based mud evaluations, and flow assurance screening with rapid turnaround. High-resolution compositional analysis is often combined with isotopic measurements to deliver extremely detailed communication studies.
Applications
Downhole PVT Samples
Once received in our laboratory, the collected fluid samples are restored via agitation at the original reservoir pressure and temperature. Initial validation checks provide basic PVT properties and a measure of oil-based mud contamination common to open-hole samples. More in-depth analyses provide additional information about specific hydrocarbon behaviors.
Data in Context
Study Questions
Are the captured samples reliable?
This question is answered by the opening pressures and initial flash validations. Opening pressures should correspond to the reported pressures from the field. The flash validations should show consistency between fluids from the same depth and, ideally, low levels of oil-based mud contamination.
How do the fluid properties compare to nearby wells?
This question is best addressed by accessing GeoMark’s Rock and Fluid Database (www.rfdbase.com).
Do the fluid properties make sense?
GeoMark offers a substantial advantage by incorporating geochemical data into our PVT studies. Geochemical markers help identify certain characteristics, like fluid thermal maturity and mixing, which are key drivers of eventual PVT behavior.
Surface PVT Sampling
Samples of gas and liquid exiting the separator are acquired, along with separate flow rate measurements of each, providing the gas-oil ratio (GOR). The fluids are then recombined in the laboratory to recreate representative reservoir fluids for accurate analysis.
Data in Context
Study Questions
Are the separator gas and oil samples reliable?
This question is answered by the opening pressures and initial flash validations. Opening pressures should correspond to the reported pressures from the field. The flash validations should show consistency between duplicate samples
What is the correct recombination GOR?
This is often the most difficult, but key question, in conducting recombined PVT studies. Ideally, the GOR should be stable for an extended period. Also, geochemical analyses are often used to confirm, or question, the validity of the planned GOR for a PVT study.
Why is the bubble point pressure so critical in unconventional oil wells?
Dropping below the bubble point pressure dramatically reduces oil production in unconventional wells. PVT studies are used to determine this pressure and identify any corresponding gap to the reservoir pressure.
EOR Testing
These tests are designed to determine the extent of gas miscibility and mixture phase behavior during gas injection into hydrocarbon reservoirs. While common in conventional reservoirs for decades, EOR programs have also found recent applicability in unconventional plays.
Surface oil and gas samples are captured and recombined to recreate downhole reservoir fluids. Injection gases may be separator or sales gas derived from a nearby installation, or synthetically prepared gas based on a composition provided to our laboratory.
Data in Context
Study Questions
Will a specified gas be miscible with an oil?
This question is answered through a PVT and EOR testing program. Compositional data is combined with EOR tests, like swelling and slim tubes, to determine the miscibility pressure.
What if a reservoir fluid is already saturated (at bubble point)?
This is a difficult situation. By definition, the reservoir fluid is already saturated with gas and won’t “accept” any more to change it properties. In such cases, the most applicable test is a multi-contact equilibrium test; whereby, repeated contacts of fresh injection gas are used to vaporize some of the light components of the oil, while also reducing its viscosity.
Why is the bubble point pressure so critical in unconventional oil wells?
Dropping below the bubble point pressure dramatically reduces oil production in unconventional wells. PVT studies are used to determine this pressure and identify any corresponding gap to the reservoir pressure.
Best Practices
Once samples are received in our lab, we pay attention to the smallest details to ensure testing accuracy. During all phases of the test program, we stay connected with you so you are part of an interactive process:
