2. About OSL
OSL is a multi-disciplined team of creative, forward-thinking technical
specialists, working collaboratively with the energy and related sectors to
provide quality implemented solutions.
Our speciality is front-end engineering
and provision of innovative solutions
for Gas and Oil Processing, Transport
and Storage - both onshore, offshore
and subsea. OSL has extensive
experience in the energy sector,
including environmentally friendly
technologies such as carbon capture,
bio-fuel and biogas. Our highly
skilled team undertake a wide range
of projects for a variety of major and
independent energy companies and
we pride ourselves on our clever
thinking, quality, timeliness and the
cost effectiveness of our delivery.
We are the leading authority in the
design and optimisation of gas
compression systems both on
and offshore. This is achieved by
“cradle to grave” engineering and
design support through innovative
thinking based on sound engineering
practices, reinforced by our extensive
operational experience.
3. Development of Tight Gas Fields
The Industry Challenge
In recent years, the exploration of
gas fields in the Southern North Sea
(SNS) has often avoided exploring
tight gas reservoirs due to high field
development costs. As a result of this,
many gas discoveries and fields have
been left undeveloped.
There are two fundamental challenges
in developing tight gas fields, the
first of which is the cost. Apart from
developing a topside platform, there
is significant and often uncertain
expense in the drilling and fracking
that is required to release the gas
reserves in the reservoirs. The cost of
drilling is particularly high when drilled
horizontally for long distances before
initiating the fracking process.
The second being the presence and
flow-back of solids in the form of
sand or proppants from the hydraulic
fracturing. Unconventional gas fields
require hydraulic fracturing in order to
recover natural gas at economic rates,
solids flow-back can cause pipeline and
equipment internal erosion and solids
deposition. Therefore, solids production
management is a critical issue to
address and is essential to prolong the
operational lifespan of pipelines and
associated production equipment.
OSL has developed a subsea
solution that addresses both of
these problems hugely reducing the
drilling costs whilst assuring the life of
pipelines and associated equipment.
A comprehensive methodology
entailing production, processing,
transportation and solids removal
is included in this package,
which will turn tight gas field
development into a highly
profitable investment.
The overall infrastructure
investment is approximately one-
third of the investment required
for a standard topside facility.
4. OSL Subsea Separation Solution
Having a wealth of experience in the
SNS, OSL has undertaken a detailed
analysis of the challenges and
conditions associated with fields that
may contain high quantities of sand
and/or proppants at the wellhead.
We have created a solution for these
fields designed to be compact and
simple, with minimal maintenance
requirements using standard subsea
components.
This solution enables tight gas wells
to be developed in the absence
of topside structures as well as
advanced and expensive drilling
techniques. The skid in our design
can be placed on the seabed and
the extraction can proceed with a
more cost-effective drilling technique,
without a long run of horizontal wells.
The OSL solution includes a self-
contained subsea separation unit,
which will be installed on the seabed
by a drilling rig on the well conductor
without the need for piling. The
unit is capable of being handled
and installed by a standard jack-
up rig and has a standard subsea
tree guide frame. It is designed to
allow for easy removal for either
decommissioning or relocation as
and when a new low reserve gas field
needs to be developed.
The main components within the
package are industry standard and
include the wellhead, separation
unit, solids accumulator, fiscal
metering station and umbilical
installations. The process will be
controlled by a standard Subsea
Control Module (SCM), which will
contain electronics, instrumentation,
hydraulic components and chemicals
to provide well control functions
during well production.
The package will be tied back into an
existing platform. This will ensure that
the platform’s life is extended as it will
become a hub for these new subsea
wells. The processed gas can then be
transferred as per every client’s need.
5. Wellhead and
Christmas
Tree
Solids
Separation
Equipment
Solids
Accumulator
Choke Valve
and Isolation
System
Flow
Metering
Device
Adjacent
Subsea
Installation or
Topsides
Onshore or
Offshore
Processing
FacilitiesSubsea
Export
Pipeline
Umbilicals
Termination
Assembly
Process
Chemical Injection
Hydraulic Oil
Power Supply
Control Signal
Subsea Separation Skid
The solids disposal process from the
solids accumulator will be completed
by periodically using a Remotely
Operated Vehicle (ROV) without
any diver intervention. Our unique
pressure reduction approach has
been devised to ensure the safety of
both personnel and the environment
during the solids removal procedure.
This method is designed to be simple,
inherently safe and cost-effective.
6. System Design
The OSL solution is very flexible and
has been designed to operate over a
wide range of operating conditions.
Marginal tight gas fields that exhibit
the following properties are ideal
applications for this comprehensive
package.
The flexibility of the solids separator
operation is an essential element
of this package. Each gas field
possesses unique associated solids
characteristics therefore the ability to
optimise the separator design using
Computational Fluid Dynamics (CFD)
techniques is a substantial benefit.
The package has stringent erosion
monitoring to track the mechanical
integrity of the equipment exposed
to solids to prevent any damage.
However, in the unlikely event of
excessive erosion over time, the
package design enables easy
replacement of equipment if and
when required.
The package is contained within
a standard skid design, which is
compact and provides ease of access
for ROV operations. The square
shaped skid is 5.8m wide, 6.4m high
and weighs 82 tonnes. It has been
optimally loaded and can be installed
on the seabed without the need for
piling using standard jack-up drilling
rig deck cranes. The steel structure
will provide adequate support,
dropped object protection and trawler
board protection to the separator,
solids management system and other
components of the skid.
The equipment contained within the
package has been optimally sized
to reduce total investment whilst
maintaining accessibility.
7. Benefits
This subsea separation package provides the following benefits:
• Complicated drilling time is
minimised, reducing drilling costs
significantly
• Capital investment is reduced by
approximately one-third, compared
with conventional development
• Shorter time to reach first gas
• No need for topside facilities
• Mechanical integrity issues of
the pipeline and processing
equipment are minimised
• Process safety is never
compromised through OSL's
Process Safety in Design (PSiD)
• Using standard subsea
components, the system has been
designed for high reliability, ease
of connection to ROVs for solids
production management, removal
and inspection, as well as simple
maintenance and servicing
• Close monitoring of any critical
equipment degradation allows
immediate and proactive action to
be taken
• Optimisation of the separator
design using CFD
• Easy removal of skid for either
decommissioning or relocation
which provides a cost-effective
long-term solution
• No negative impact on the sea life
and its environment through simple
and compact technology
This solution provides a
significant opportunity to
reconsider some of the
unexploited fields at a cost
effective price point. Thus - tight
gas fields in the SNS have not
been more attractive to develop.
8. Engineering Creative Solutions
for our Energy Future
/oslconsulting
@oslconsulting
OSL Consulting
OSL Consulting
OSL House
Henry Boot Way
Priory Park East
Hull
HU4 7DF
View this document online at
www.issuu.com/oslconsulting
Tel: +44 (0) 1482 626400
www.oslconsulting.com
info@oslconsulting.com
