UNCONVENTIONAL DRILLING
Automated geosteering
algorithm shows promising
ability to match human
geological interpretations
H&P undertakes field testing in Haynesville
to validate technology that supports more
efficient analysis of target formation
BY JESSICA WHITESIDE, CONTRIBUTOR
The developers of an automated geosteer-
ing algorithm aim to take the more mun-
dane tasks related to the monitoring of
geological data and generation of geologi-
cal interpretations off the plate of the geo-
steerer, so they can apply their expertise to
more complex challenges.
Geosteerers interpret real-time geologi-
cal data from downhole logging-while-
drilling tools, often a gamma ray module,
to help drilling crews make directional
changes for a better path to the pay zone.
Geosteering analysis is particularly impor-
tant in two key areas of wellbore place-
ment: achieving the optimal landing point
and guiding the lateral through the target
formation. The geosteering process is labor inten-
sive, requiring continuous monitoring and
interpretation of data that can limit a
remote supervisor to watching only two
or three operations at a time. But what
if that one expert could simultaneously
monitor even more wells, with less stress
and greater efficiency, through the appli-
cation of technology? That thought was
one impetus for the automated geosteering
algorithm that Helmerich & Payne (H&P)
developed and field-tested on two Sabine
Oil & Gas wells in the Haynesville Shale.
The geo-correlation algorithm is
designed to expand the geosteering capac-
ity and efficiency of remote operations
centers by using automation to handle
routine monitoring, as well as survey
updating that requires no immediate deci-
sions. This would free up geosteerers to
28 focus on the most challenging intervals
in each well where meaningful decisions
are required, such as steering changes or
choosing between multiple interpretations
when enough data is ready for review.
“It’s not that we want to replace some-
one or remove their job. It’s that we want to
make sure that person can be more effec-
tive, watch more wells and leverage their
talents in a better way,” said Marc Willerth,
H&P Technology Development Manager.
He discussed the algorithm and its field
testing at the 2022 IADC/SPE International
Drilling Conference in Galveston, Texas,
on 10 March.
Minding the misfits
To help the geosteering team identify
the best pathway through the formation,
the algorithm uses a stratigraphic heat
map to visually represent interpretations
of geological data, including stratigraphic
depth and gamma ray signature measure-
ments. The heat map’s coloring indicates the
probability of encountering rock that
matches type log expectations. Areas of
low probability (high misfit) appear as yel-
low, while those with higher probability
(low misfit) are preferable and use darker
tones. “The theory here is that if you build a
path through these dark zones, this com-
bines both what rock you are likely mea-
suring from a geology perspective with
what rock you are likely measuring from
a geometry perspective,” Mr Willerth said.
Validating the system
H&P had previously tested the algo-
rithm against historical drilling data, but
the Haynesville project provided the first
opportunity to apply the algorithm to the
real-time workflow of a drilling operation
as crews developed the lateral sections of
the two subject wells.
For this field trial, the team intentionally
chose an area featuring benign geology
with no major faults or dips so it would
lend itself to straightforward interpreta-
tions. “Basically, if we couldn’t steer this with
our algorithm, we were going to struggle
just about anywhere,” Mr Willerth said.
“But we thought it was a good opportunity
to give it a try, and it’s also potentially your
highest value place for an early automa-
tion solution. If you can take the simplest
things and allow expertise to be focused
on the more complicated areas, that in and
of itself is already a win.”
The field deployment offered a head-to-
head comparison of the interpretations of
traditional geosteering services and the
automated system, which was periodi-
cally monitored by a geo-professional. The
team’s goal was not only to see if the
algorithm could produce results similar to
a human, but also to quantify how much
effort would be required from a human to
ensure that the algorithm’s interpretation
was reasonable.
The team checked the interpretations
for three primary factors: estimated land-
ing point, modeled geologic structure
throughout the lateral, and the estimated
footage of the wellbore in the target zone.
In both test wells, the automated system
estimated the same landing point tie-on
and percentage in zone as traditional geo-
steering. “We were excited to see that there was
broad agreement in the key variables we
were testing,” Mr Willerth said.
While the algorithm’s estimated bed dips
across the lateral also closely matched
those from the human interpretation, there
were some minor issues in which the algo-
rithm added irregular artificial structures
– a hump in the first well and some jagged
cusps in the second – that required inter-
vention through the addition of control
points to create a more realistic formation
shape for the area.
M AY/J U N E 202 2 • D R I L L I N G C O N T R AC T O R