Autonomous inflow control
technology could provide the key to enhance oil production from produced water
treatment operations, while significantly reducing emissions. A recent study
has shown that advanced completions could help the industry safely and
sustainably accelerate net zero ambitions.
Dr. MOJTABA MORADI, Tendeka
nature, the oil and gas industry has the resourcefulness and resilience to
eliminate unnecessary carbon emissions. However, traditional development plans
have relied on the application of conventional wells, with minimal or no
emphasis on the well completion. This produces a mixture of oil and other,
often unwanted fluids, such as water and/or gas, and it requires a costly,
energy-intensive separation process at the surface.
The result is excessive and unnecessary GHGs being emitted
into the atmosphere. While the process has been optimized to some extent, with
unwanted fluids often re-injected back to the reservoir, it is now widely
recognized and accepted as one of the greatest challenges facing the industry
in its drive toward net zero delivery of energy.
Rate-controlled production (RCP) autonomous
inflow control devices (AICDs), self-regulating devices—based on the properties
of the fluid passing through—have been applied successfully in numerous light
and heavy oil wells to greatly reduce the production of excessive, unwanted
water and gas. The fully interchangeable device, field-adjustable and
engineered for a wide variety of applications, negates the need for costly
treatment at the surface and preferentially chokes unwanted produced fluids,
while allowing oil production from the entire length of the well. The design
and deployment of such devices vary widely, as do their application in
injection and production wells, as well as different types of reservoirs.
Several operators have reported a significant
reduction of up to 60% in water treatment requirements while optimizing oil
production. Consequently, this has markedly lowered greenhouse gas (GHG) emissions.
A study by
Tendeka, a TAQA company, utilized both a workflow methodology and a publicly available GHG
footprint estimator to illustrate the significant impact of its FloSure AICD, Fig.
1. This was to reduce GHG emissions on two typical oil fields—onshore, cold heavy oil productions,
and light oil, highly productive offshore wells.1
The performance of each development, in terms of GHG
emissions and energy consumption, was evaluated with, and without, the
autonomous completions, when a fixed volume of oil production for each field is
AUTONOMOUS INFLOW CONTROL
Across oilfield developments, flow control devices are
proven to optimize the performance of both injection and production wells. Much
like the function of a standard ICD, the AICD was designed to balance the
influx of reservoir fluids in production wells, by proactively delaying the
production of unwanted fluids before breakthrough. However, once a breakthrough
occurs, the AICD works to autonomously limit undesired materials with lower
viscosity, such as gas and water, from entering production wells.
Injection wells are used to either store the
unwanted fluids or reinject them to improve oil recovery from production wells.
AICDs have been designed specifically to optimize the performance of injection
wells by improving the injection conformance, thereby reducing injection cost, improving
field NPV and boosting the reliability of injection well systems.
As shown in Fig. 2, the AICD is
normally assembled as part of the sand screen joint, if required. The flow path
from the reservoir is marked by blue arrows. The fluids from the reservoir
enter the completion through the sand screen jackets and move into the AICD
housing, where the device is mounted. The fluids then flow through the device
and into the production fluid conduit and flow to the surface. Figure 3
illustrates the components of the FloSure AICD device.
shown above, fluids from the reservoir enter the device through an orifice in
the top plate, impacting the levitating disk and dispersing radially between
the disk and the top plate, before the fluids turn around the edge of the disk
to leave through the ports at the bottom of the device. The degree of flow
restriction is a result of the position of the levitating disk, while the disk
position is determined by the balance of three principal forces:
Figure 4 shows the AICD performance curve for various
fluids under single-phase conditions. The pressure drops experienced by fluid
flowing through the AICD is a function of the volumetric flow rate and the
viscosity and density of the fluid.
IDENTIFYING AND COMBATTING GHG ACTIVITIES
The production of unwanted fluids has been an
inherent challenge for the oil and gas industry. Not only do they lower oil
production efficiency, they are also associated with other unavoidable problems,
including well integrity and limitation on the capacity of surface processing
facilities. The treatment and re-injection of fluids back to the reservoir
further compounds the costs and consequences associated with GHG emissions and
energy consumption. AICDs are a proven technology to control unwanted fluids in
the ground and mitigate economic and environmental issues.
From exploration to the production stage, the
GHG footprint estimator predicts the amount of GHG emitted from any individual
operation, process and treatment. This calculation enables the operator to
recognize the major GHG emitter activities and use novel and enhanced
technologies, methods and/or workflows to optimize the process toward achieving
investigation carried out a comparison, in terms of GHG emissions and energy
consumption, between two typical oilfield developments—with and without an AICD
completion—when a fixed volume of oil production for each field is assumed:
The calculation was performed, using an
algorithm developed by Stanford University. The parameters assumed in the study
are shown in Table 1 for both fields. The gas composition was assumed as
N2, CO2, C1, C2, C3, C4+
and H2S, with mole fractions of 2, 4, 86, 4, 2, 1 and 1
respectively. No flaring was permitted for all fields. Several other parameters
were assumed throughout the study.
COMPARING TYPICAL OILFIELD
Field A: AICD to control
water production. High-viscosity
fields pose several challenges, including production of a high volume of water.
Oil is often left behind, and wells usually operate at a high water cut—up to
99%—even during the early days of production. The application of AICDs has
helped to reduce the amount of water production for many wells across the world.2
As Table 2 shows, the amount of GHG
emissions and energy consumption could be significantly reduced by the
deployment of AICDs (67% and 82% respectively), compared to non-AICD wells for
this example. Figures 5a and 5b show the GHG emissions
contribution from each operation involved in oil production for both scenarios.
The data suggest that production and surface processing are the major factors.
Table 3 provides the contributions of these two
operations in both total GHG emissions and energy consumption.
Field B: AICD
to control gas and water production. Highly productive offshore wells usually
suffer from production of a high volume of gas and often excessive water
production, which would lower oil production. If they are not equipped for AICD
completions, this could result in choking back the wells. However, results from
numerous applications have proved the success of applying AICDs to reduce gas-oil
ratio (GOR) and water cut (WC) in such fields.3 Lowering GHG
emissions, while delivering a fixed volume of oil from these wells, could
eventually result in a reduction in the required number of wells, as shown in Table
2 shows, the amount of GHG emissions and energy consumption in Field B
could also be significantly reduced by the deployment of AICDs (26% and 30%,
respectively), compared to non-AICD wells. Table 3 summarizes the contribution of production
and surface processing operations in both GHG emissions and energy consumption.
Again, these operations are the major contributors to GHG emissions. In this
case, the surface processing facility is the highest contributor, with a share
of about 78% and 90% respectively, in wells with and without AICDs.
NET ZERO AMBITIONS
Growing energy demand, intensified by the
fallout of Covid-19, conflict in Ukraine, and pressure to tackle climate change,
has seen the oil and gas industry hasten the adoption of smarter and more
sustainable technologies, to secure supply and cut costs and emissions. Advanced well completions, using sophisticated
autonomous flow control technologies, have already shifted the paradigm for
many global operators.
The study by
Tendeka, utilizing a workflow methodology and a publicly available GHG footprint estimator, has
shown that the use of AICDs minimizes the production of unwanted fluids in two
different oilfield developments. The results could radically reduce
requirements of the energy-intensive treatment process and prove that advanced completion
could help the industry to
achieve net zero targets while optimizing oil production. WO
MOJTABA MORADI is a Subsurface manager at Tendeka in
Aberdeen. He holds a PhD (2016) in petroleum engineering from Heriot-Watt
University. He is a member of the European Association of Geoscientists and
Engineers (EAGE), and SPE.