FAQs


Laboratory Services


What type of samples can be tested?

H2 Laboratories is able to test many different lithologies, including clastics and carbonates. Several sample reports are available upon request. Tests are performed on core plugs (standard plugs and sidewalls), in our laboratory. Maximum sample size is 60mm long, and 51mm in diameter.



What is the minimum sample size?

H2 Laboratories NMR SCAL techniques are limited not strictly by sample size, but by the volume of fluid held within the rock matrix itself. In order to achieve an adequate signal to noise ratio (SNR) from a sample, a certain minimum volume of fluid must be present in the rock. Typically, the minimum fluid volume necessary in the core plug is 0.2 ml for capillary pressure testing, or 0.05ml for standard NMR measurements.


Do your tests work on unconventional samples?

In unconventional reservoirs, the very small pores are often the dominant contribution to the total porosity of the core samples. To visualize the fluids in small pores, the measurement parameter known as TE (Time to Echo) must be as short as possible. The Oxford Instruments GeoSpec2 rock core analyzer, which we use in our laboratory, acquires data with TE as short as 60 μs, the best commercially available performance in the industry. The shorter the echo time provided by the NMR instrument, the shorter T2 that can be resolved, enabling smaller pore sizes to be detected.

 

What are the advantages of the GIT-CAP technique?

Porous plate is considered the gold standard for calculating capillary pressure, but it is extremely slow. Mercury injection is very fast, and requires only a small sample, but it is destructive and uses a non-representative fluid. Traditional centrifuge techniques may still take several weeks to generate a full capillary pressure curve, as one spin is required to obtain each point (7- 10 in all) on the curve. H2 Laboratories technique is not only faster (2 spins), but also more accurate as it does not require the same assumptions as the traditional centrifuge method. Rather than measuring expelled water, our technique measures actual in-place water saturation at 30 to 40 points along the core plug non-destructively, and in a single spin.

 

What about redistribution?

A common question about our NMR techniques is "what about fluid redistribution?". Over time, it just makes sense that fluid within a core plug will redistribute once the rock has been removed from the centrifuge. H2 Laboratories has tested numerous rocks of varying permeabilities and found that redistribution does occur, but over time frames much longer than those necessary to obtain the NMR measurement.

 

What is the difference between CT and NMR services?

As in medicine, CT and NMR/MRI are complementary, rather than competitive techniques. Depending on the application, one modality will be more appropriate than the other. In medicine, for example, CT is typically better for examining bones, whereas MRI would be the scan of choice to examine soft tissues. When it comes to rocks, H2 Laboratories Ltd.'s technique measures the actual fluid in the rock. CT, by comparison, measures the matrix of the rock, but results in modeled (not measured) fluids.

 

What about the "standard" cut-offs (or Why should I recalibrate my well logs)?

For a number of years, the industry has used 33ms as a standard T2 cut-off for sandstones. While appropriate for the conventional sandstones on which it was originally measured (Dunn et al., 1994), in today's unconventional reservoirs, this number is not appropriate. In H2 Laboratories tests, T2 cut-offs for "tight" sands have been measured at as low as 0.5 msec. Redefining cut-offs based on core measurements may have a significant impact on the calculated reserves.

 

What information do I need to provide along with my core plugs?

H2 Laboratories requests that you provide four pieces of information, if possible:

- desired brine composition
- desired pressure for desaturation
- porosity
- permeability

Unless otherwise specified, we will use 2% KCl brine, and can estimate the pressure to use if unknown. Porosity and permeability are helpful, but not mandatory, inputs to our process.

 

Where are your testing services located?

All H2 Laboratories specialty SCAL tests are carried out in our own testing facility located in Fredericton, New Brunswick, Canada.