I was able to
attend this important talk, or “science chat” as Mike referred to it, given to
the Ohio Geological Society in conjunction with the Ohio Oil & Gas
Association Annual Winter Meeting. The talk was titled, Cuttings Volatiles: Produce
More Oil, More Gas, and Less Water. Having worked extensively with drill
cuttings early in my career and some with cores later on, I know the value of
analyzing rocks in hydrocarbon exploration and understanding. It turned out to
be a great talk and I think he showed conclusively that the techniques he
developed can be valuable in quite a number of ways and for quite a few different
applications. I lost my notes from the talk, so I am relying a lot on the
website which includes several presentation slides.
Mike Smith
actually invented these techniques and holds numerous patents. First, he invented
the Fluid Inclusion Stratigraphy (FIS) which is now marketed by SLB, when he
was with Amoco Research in the late 1980’s and early 1990’s. He started
Advanced Hydrocarbon Stratigraphy (AHS) in 1994. In 1999 he sold AHS’s Fluid
Inclusion Volatiles (FIV) to ExxonMobil in 1999. Ten years later after being a
consultant for ExxonMobil he restarted AHS focusing on analyzing volatile
fluids and gases from drill cuttings and cores. He invented a unique Cryo-Mass
Spectrometer for extracting and analyzing present day oil, gases, and formation
water from cuttings. This device utilizes liquid nitrogen to freeze samples to
very low temperatures and depressurization to allow gases and fluids to be
gently vacuum extracted from the rocks for content determination and analysis. Samples
are typically extracted at two different vacuum pressures, 2 and 20 mbar. Current
services from AHS include rock volatiles stratigraphy (oil and gas payzone maps),
frackability evaluation, mud volatiles stratigraphy, real-time core samples
volatiles analysis, advanced hydrocarbon analytics, and other customized services.
Source: Advance Hydrocarbon Stratigraphy Website
AHS is in partnership
with Baker Hughes to offer these services to the oil and gas industry. The
service is known as Rock Volatiles Stratigraphy (RVS). Successful applications
have included targeting laterals and recognizing bypassed pay zones. Another
app that has been explored is relating hydrocarbon content to structure and associated
fracturing. Methane loss without loss of heavier NGLs can indicate presence of
a fault where methane as a smaller molecule can be lost but larger molecules like
ethane, propane, and butanes, are retained. Analysis of faults as migration
pathways is a focus. The same could be done with unconformities as migration
pathways. For oil migration a high toluene/benzene ratio at a fault is an indicator
of migration. High ascetic acid content can indicate communication with a fault.
Permeability and water saturation can be assessed. Water saturation can be determined
from 2 mbar extraction and permeability can be determined from the ratio of
response from different pressures of extraction (2mbar and 20mbar). Geochemistry
can also be used to evaluate conditions of compartmentalized reservoirs which
can account for different production performances of wells. Data can also be
used to compare to historical data to show changes that have occurred in a
reservoir over time.
AHS can analyze
cuttings and of any vintage, core samples, and drilling mud for present-day
volatiles. Mike’s previous inventions of FIS and FID where limited to discerning
the past conditions of petroleum systems. Oil and gas applications of cuttings volatiles
analysis include determining the best target zones for laterals, determining the
best perforation zones, frac stage design, mapping oil and gas migration, and
determining present conditions of produced reservoirs. The tech can also assess
reservoir seals, reservoir compartmentalization, resource quality, thermal
maturity, parent well-child well relationships, reservoir drainage, and rock
properties like mechanical strength. Chemical analyses include small molecules
like CO2, oxygen, and nitrogen; noble gases like helium and argon; hydrocarbons
like C1-C10, sulfur compounds (H2S, SO2, and more), biological byproducts
(organic acids like formic acid and acetic acid), and diagnostic signatures
like ethene and 2-trans-butene. Samples for gas analysis are best collected and
sealed onsite since gases can be lost quickly to the mud and atmosphere. Highly
pulverized PDC bit cuttings can be analyzed.
Geothermal applications
of cuttings volatiles analysis can be valuable. In wells too hot to log this
analysis can provide important information. It has been used in the recent DOE
funded FORGE enhanced geothermal systems (EGS) project in Utah to evaluate post-hydraulic
fracture zones of the best induced fracture zones. It can also be used to
indicate fracture zones in conventional geothermal wells and connections to the
deeper hydrothermal system where wells utilize convective heat flow. Sulfur mineral
analysis can inform corrosion hazards. FORGE wells are being developed adjacent
to a hydrothermal system to take advantage of a controlled induced fracture
system. AHS analysis was able to determine water content, fracture porosity,
fracture density, and rock mechanical strength to inform well stimulation. Geochemical
data can also point to communication with the hydrothermal reservoir and communications
between an injection well and a production well.
Helium
analysis can indicate seal validity and integrity. It can also evaluate helium
content to inform helium exploration. Effects of structural features on helium
content, seals, baffles, and migration conduits can be determined. Helium
movability/permeability can be determined. AHS tech is able to detect and analyze
very small amounts of helium entrained in rock samples.
Rock volatiles
stratigraphy can be used to de-risk reservoirs for CCS/CCUS before drilling carbon
sequestration wells. They can predict the potential for CO2 to escape or
determine if it had escaped in the past by characterizing past CO2 migration, changes
in reservoir pressure, communication through adjacent boreholes, and
communication via meteoric water. They can determine whether rocks are CO2-philic
or CO2-phobic, or whether they will accept or reject CO2. It can assess CO2
movement along faults which can indicate potential for CO2 leakage out of
intended storage reservoir. They did a big study with the Kansas Geological
Survey assessing risk for CO2 leakage in the Stack Play in the Mississippi Lime
in NW Oklahoma and are currently working on CO2 storage assessment in the San
Juan Basin of New Mexico.
AHS offers
some great services utilizing detailed geochemical analysis of rocks. This data
can reveal a vast amount of information that can inform oil and gas economics,
CCS/CCUS suitability and conditions, geothermal suitability and conditions, and
helium prospectivity.
References
Cuttings Volatiles:
Produce More Oil, More Gas, and Less Water. Mike Smooth, PhD. Talk given to
Ohio Geological Society in Conjunction with the Ohio Oil & Gas Association
Annual Meeting. March 8, 2023.
Geothermal Applications
of RVS: Initial Results from FORGE 58-32 Well. Christopher Smith (PhD).
Advanced Hydrocarbon Stratigraphy.
Geothermal
Applications of RVS Initial Results from FORGE 58-32 Well - AHS
(advancedhydrocarbon.com)
Rock Volatile
Stratigraphy (RVS): Carbon Capture and Utilization Storage-Site Assessment
Applications. Christopher Smith, PhD. Advanced Hydrocarbon Stratigraphy. March
28, 2022. Rock
Volatile Stratigraphy (RVS): Carbon Capture Utilization and Storage-Site
Assessment Applications - AHS (advancedhydrocarbon.com)
Baker Hughes Volatiles
Analysis Services (VAS): Supplied Through Advanced Hydrocarbon Stratigraphy
(AHS). Christopher Smith, PhD. Baker
Hughes Volatiles Analysis Services (VAS) - AHS (advancedhydrocarbon.com)
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