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GeoMark Research, Ltd.

9748 Whithorn Drive 
Houston, Texas 77095

GeoMark Research, Ltd.


PVT Analyses


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. 

PVT Services

GeoMark Research’s established PVT laboratory has been serving the industry for over 15 years, providing critical subsurface fluid insights for our global customers:

  • Fluid Phase Prediction: Predict when in-situ fluids will transition to multiple phases (bubble point and recoverable hydrocarbon insights).
  • Well Interactions: Evaluate how parent-child relationships are affecting PVT behavior.
  • Reservoir Continuity & Communication:  Pressure assessment to identify reservoir communication.
  • Production Management: Fluid property assessment for optimizing choke management and production infrastructure.
  •  Field sampling and wellsite services
  • Sample transfer, validation and restoration
  • PVT tests up to 20,000 psi and  400 degrees
  • Reservoir fluid phase identification
  • Surface separator fluid recombination
  • Constant Composition Expansion (CCE)
  • Differential Liberation (DL)
  • Constant Volume Depletion (CVD)
  •  Multi-stage separator test
  • Pressurized and Stock Tank fluid viscosities
  • EOR – Minimum Miscibility (Slim Tube), Swelling and Multi-contact (reverse and forward)
  • Flow Assurance – Asphaltenes and Waxes
  • Long-term pressurized sample storage
  • Working pressure maps
  • PVT Cylinder Storage (Short and Long term)


PVT analysis is the scientific process used to determine phase behavior and fluid properties of oil and gas samples from your well—both in the reservoir (downhole) and at the surface. This analytic testing information gives you a better understanding of your hydrocarbon reserves, so you can apply the most cost-effective extraction methods to optimize production. Refer to PVT Lab Testing – Best Practices.

Downhole PVT Samples

Downhole samples are primarily acquired by the customer directly from oil and gas wells located offshore. The sampling tools are often conveyed on wireline and activated from the surface to capture representative fluids. Advanced single-phase chambers keep the fluids above reservoir pressure, despite cooling during transfer, helping to avoid pressure drop induced asphaltene precipitation.

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.

Surface PVT Sampling

Surface sampling of reservoir fluids is taken from individual gas and liquid streams from a production separator or similar installation. Other than methods used for new offshore wells, it is by far the most common method of sampling pressurized hydrocarbon fluids.

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.

EOR Testing

Standard enhanced oil recovery (EOR) and (PVT) testing programs include experiments, such as solubility/swelling, multi-contact, slim tube, vapor-liquid equilibrium (VLE), and fluid property measurements.

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

GeoMark maintains a database of thousands of offshore PVT reports (www.rfdbase.com) for easy reference. This data provides excellent context when considering the behavior of new fluids. For example, fluids with complex geochemical sourcing usually have different PVT properties than those with more straightforward pedigrees.
Downhole oil samples are collected by a third-party service provider and sent to GeoMark’s lab. For surface oil testing purposes, GeoMark sends a highly experienced sampling engineer to collect samples at your site. We follow a strict, step-by-step procedure when collecting and transporting the samples, including type of cylinders and equipment specifications to ensure valid sampling.

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:
Validation phase – The first thing we do is validate your sample and share preliminary general results to you via email or phone, rather than waiting until the entire testing cycle is completed. This extensive validation also includes checking for any leaks or errors that may have occurred in sample collection or transportation.
In-depth testing phase – We use the latest technology to accurately measure oil components and PVT parameters. In fact, we don’t just measure once, we measure twice! But, before doing any tests, we communicate with you to ensure the right tests are ordered, making adjustments if needed. Our lab technicians stay in touch with you during the course of the testing program, so there are no surprises.
Final reporting phase – Depending on the scope of the project, you will receive a final written report typically in 4-6 weeks, containing all the laboratory findings. This fast turnaround time is made possible by our lab’s 24-hour operation. We offer to discuss the results, if desired. In some cases, things may not seem reasonable; that’s where our extensive PVT database with similar cases can add a level of comfort that all is within the norm.

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GeoMark Research, Ltd.
9748 Whithorn Drive | Houston, Texas

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