DRILLING OUTLOOK
A panel of industry experts discussed challenges and opportunities around geothermal development at the 2022 IADC ART
Conference on 30 August . Pictured are (from left) Joey Husband, Nabors Drilling; Cindy Taff, Sage Geosystems; Barry Smither-
man, Texas Geothermal Energy Alliance; and Gustavo Perez, EarthBridge Energy.
eration. Producing more power per well
can reduce the number of wells that need
to be drilled.
“Projects with super-hot rock and higher
temperatures will deliver a higher magni-
tude of power per well,” Mr Husband said.
“If you can deliver 30 MW per well and
reduce the number of wells you need, that
really reduces your development costs.”
Interest in geothermal
Some work may also be needed to
change how the public perceives geother-
mal energy, Mr Smitherman said. Because
it still only makes up such a small percent-
age of the global energy mix, geothermal is
not often discussed as a reliable renewable
resource. However, given the thin margin
between available supply and demand,
the additional volumes geothermal can
provide would be valuable.
In Texas, Mr Smitherman noted that
the Electric Reliability Council of Texas
(ERCOT) anticipates having around 90 GW
of installed power available from all avail-
able energy sources next year, while usage
is estimated to peak at around 80 GW,
typically in the summer months. Any dis-
ruption to the power supply – like Winter
Storm Uri in 2021, which took an estimated
50 GW of power off the grid – could spell
26 catastrophe for the state. The TXGEA is
currently crafting an agenda for the Texas
State Legislature on potential steps to pro-
mote geothermal development.
“We’re dealing with a fairly small mar-
gin when it comes to summer heat. If 90
GW is all we’re going to have next sum-
mer and if we have an interruption – like
if a nuclear plant goes down or we have
some weather event – then we’re going
to need every megawatt we can find,” Mr
Smitherman said. “If we had an additional
1,000 MW of geothermal that could’ve been
dispatched during the most critical time
of Winter Storm Uri, we could have ridden
through some of the outages and avoided
the highest price spikes that we saw. We’ll
take whatever we can get, because we are
likely going to be tight on several occa-
sions going forward.”
Geothermal can also play a role in cre-
ating localized microgrids, or intercon-
nected loads that act as a single control-
lable entity, Ms Taff said. These microgrids
can disconnect from traditional grids and
operate autonomously, providing a sus-
tainable power-generation option that
also protects against grid failure. Sage
Geosystems is working with the US Air
Force and the Texas Air National Guard
on a feasibility study to deploy closed-
loop geothermal energy systems to supply
power to Ellington Field Joint Reserve
Base in Houston. The aim is to build a geo-
thermal power facility at a military instal-
lation in Texas in the near future.
Geothermal-powered microgrids can
also provide sustainable energy to under-
served areas that may lack adequate
transmission infrastructure. “You can go
into the middle of Kenya, where there may
not be the structures that can generate
electricity, drill a single well and produce
that 3 MW of power,” Ms Taff said. “It can
service communities without having to
rely on long transmission lines.” DC
“There are a lot of initiatives going on to reduce
the risk in geothermal, including surface work on
the rig and downhole technology to handle both
the BHA and the completions.”
- Joey Husband, Nabors Drilling
NOVEMBER/DECEMBER 2022 • DRILLING CONTRACTOR
WELL CONTROL & PRESSURE CONTROL EQUIPMENT
Saudi Aramco applies 4IR
technologies to improve safety,
well control readiness at rig site
Auto Well Space Out, Wireless Remote BOP
Control and upgrades to BOP hydraulic hoses
all aim to facilitate well shut-in, evacuation
BY MICHAEL AFFLECK, ARAMCO OVERSEAS COMPANY; RICHARD PYE, BODONG LI
AND GUODONG (DAVID) ZHAN, SAUDI ARAMCO
Despite the best efforts of everyone
involved in drilling a well, accidents still
occur, and some of them result in loss
of life or permanent injury. To address
this challenge, Saudi Aramco’s research
teams in Aberdeen, UK, and Dhahran,
Saudi Arabia, are working on three new
technologies, enabled by Fourth Industrial
Revolution (4IR) innovations, targeted at
shutting in the well in a timely and safe
manner in the event of an emerging well
control situation.
Current state
What’s below the Earth’s surface is
usually relatively unknown, even though
efforts are made to predict pressure gradi-
ents, design casing programs from offset
wells and engineer drilling fluids to drill
the well safely.
Due to a variety of reasons, such as
pockets of overpressured formation, an
underestimation of the formation pressure
or poor drilling mud management, forma-
tion fluids can be unintentionally intro-
duced into the wellbore. Depending on the
size of the influx, they can significantly
reduce the effective bottomhole pressure
as they make their way up the annulus.
As formation fluids (water, oil or gas)
migrate up the wellbore, the incident
worsens with time, and well unloading
accelerates. Gas kicks can be extremely
dangerous as the gas comes out of solu-
tion and expands rapidly due to the reduc-
ing pressure. It is always better to act
early and decisively to contain a poten-
tially out-of-control well. Thus, techniques
and training, including regular practice
drills at the rig site, currently focus almost
entirely on early intervention. Drillers are
required to check the well for undesirable
flow and shut in using blowout preventers
(BOPs). Before closing BOP valves or rams, the
driller must calculate that no obstruc-
tion lies across the valve being used. An
obstruction will almost certainly prevent
some BOP sections from securing the
well. The most common tubular string
obstruction is the tool joint. Pipe sections,
including the connections, are typically
30- to 44-ft long, with the connections
themselves approximately 12 to 18 in. in
length. If necessary, an obstruction must
be moved away from the valve to be actu-
ated by changing the string vertical posi-
tion using the main rig hoist or draw-
works, or spacing out.
For reliability and security, drilling
standards dictate that the monitoring and
control of the BOP systems must occur
through wired connections, at fixed loca-
tions on the drilling rig location. On a land
rig, such locations typically include the rig
floor, the BOP control unit (often under the
rig) and at the toolpusher’s office. In the
event of a developing well control incident,
response time is key to how the event will
turn out. A best-case scenario is one where
the incident is spotted early, the well is
shut in, and the influx is safely circulated
out of the hole. However, all too often, situ-
ations are not spotted early. Figure 1 shows
how the severity of an incident increases
exponentially with time.
Depending on the situation and the
equipment available at the rig site, it may
be that the only safe method of assessing
and initiating the corrective process is
from a remote location. In Figure 1, this
period is represented by column C.
Column B represents the period of
uncertainty where there is often no single
correct course of action. How much more
effective would it be to have a procedure
for rig evacuation during this period? In
blowout situations, which invariably lead
to rig fires, it is the personnel closest to
the rig floor at the time who are usually
severely or fatally injured.
Figure 2 shows the increased safety
window or margin associated with the
ability to remotely function a BOP system
to shut in a well. Although it is possible to
activate the wireless remote control unit at
point A, procedures are expected to dictate
that wired stations on the rig are used
until the event has escalated to a severity
represented by point B. During the period
t1, the BOP system is capable of control by
both the traditional wired panel system
and by a supplementary wireless remote-
controlled system. At point C, the crew is
forced to evacuate the rig; with current
systems, no further control is possible.
During period t1, with the knowledge
that monitoring and control is still pos-
sible beyond evacuation, companies can
instruct personnel to evacuate potentially
hazardous zones earlier than may be the
case today (point B vs point C). The time
and/or severity escalation during periods
t1 and t2 effectively becomes an increased
safety window. Period t2 on the horizontal
axis is defined as the time during which
rig evacuation begins at point C, and the
window of opportunity to shut in the well
ends at point D, at which time the wireless
system is unable to secure a well shut-in,
“The Wireless Remote BOP control system
provides the rig crew an opportunity to evacuate
earlier, increasing the potential to save lives.”
DRILLING CONTRACTOR • NOVEMBER/DECEMBER 2022
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