Fishing operations can be complex and,
until now, such tasks have been performed somewhat “blindly,” which runs the
risk of turning any job into a time-consuming saga. Now, a new tool has
finally brought the oft-reviled challenge of downhole fishing into the digital
NICODIMOU, Welltec, and ROY KRISTIANSEN,
often require the application of great force downhole, to retrieve hardware or
tools that have been unintentionally lost or stuck downhole. With an inherent
lack of sophistication characterizing many traditional fishing solutions, and with
the diminishing assistance of gravity in horizontal wells, two problems became
more prominent in deeper and extended-reach situations. Firstly, getting to the
fish, and secondly, recovering items without compounding the issue.
When fishing in traditional vertical
wells, the operation relies on gravity to supply the forces downhole to
complete the operation. The laws of physics dictate that as the well becomes
more horizontal in nature, the gravity force will diminish until it reaches a
point where it is ineffectual.
With the prominence of conveyance platforms
like the Well Tractor, half the problem was solved, as the e-line-deployed
solution easily overcame the limitations of traditional operations in highly
deviated wells by driving tools to any target depth. However, traditional
pulling and fishing tools were created for vertical use, or fully mechanical
applications, leaving the need for a reliable tool to engage with the fish at
the business end of the tool string. Another shortcoming of traditional tools
is that they often rely on any force applied at surface to be successfully
transmitted to the desired point downhole—a task that becomes increasingly inefficient
and difficult, if not impossible, with increasing well deviation.
FILLING A CRUCIAL GAP
There was a gap in the intervention
market, as all the traditional pulling and fishing tools were created for
vertical, fully mechanical applications. After Welltec introduced the robotic tractor,
the missing link was the tool that engaged with the fish. With that, there are
some challenges, such as traditional tools that are made with different pins,
or screws that
are required to be mechanically sheared in order to release the tools downhole.
By allowing reliable disconnect of
fishing strings or relocating the fish in the well, the electric release
fishing tool is designed to improve and simplify fishing operations. The
required grapple type, either external or internal, can be easily assembled on
the tool by only changing a few parts, Fig. 1. Electrical
disconnect can be activated at any time, when required.
Since the development of well
tractors, the industry has invested hundreds of millions of dollars in
conveyance equipment. All the focus was on the conveyance methodology, but the
actual tools at the end of the tractor were still the same mechanical tools
that had been developed over 50 years ago. That is where the Wellgrab electronic
fishing tool (Fig. 2) comes in. With this technology, one can engage the
fish and pull it out without having to rely on pins. Also, if you are stuck in the
very object that you are trying to recover, you are not relying on having to shear
a pin to get loose.
MEETING THE DIGITAL
majority of operations in the oil field now
digital, operators can communicate with nearly all their tools—except fishing tools. This
creates the juxtaposition of having invested in digital equipment, yet still
depending on 50+ years-old technology with low-level feedback, meaning almost
full reliance on the experience of a crew when it comes to retrieving lost or
Operating on e-line, the Wellgrab ERFT
(Electric Release Fishing Tool, Fig. 2) resolves this issue by utilizing
a range of external and internal grapples to match the specific requirement of
engaging a downhole fish. Communication with the grapple is supported by a
system measuring multiple parameters, all integrated with an actuation device,
such as Welltec’s 100K Well Stroker, which can deliver up to 100,000 lbs of
force directly where it’s needed: downhole at the exact fishing point. Most
traditional tools would be ripped apart under such force, making this solution
a first for the oil and gas industry.
These features have proven to be highly
beneficial in the field, proving in one case that an available engagement
length of just 29 mm was sufficient to retrieve a parted tool string (with a
stuck mill bit) with 33,000 lbs of force. In a situation like this, it’s all
about optimization, with real-time information on tool performance greatly
enhancing operations, enabling tasks to be completed more quickly and
efficiently than by conventional means.
The solution is not a single tool, per se; it is more like a platform
for multiple tools, creating a single solution, akin to that of a Swiss Army
Knife, with multiple applications. All that is required is to change the grapple
at the end of the tool (Fig. 1), and this includes plug
SURFACE CONTROL AND THE
As the ultimate fail-safe, a
release-on-command electrical signal can be sent to the grapple at any time. In
the unlikely event that the signal is lost, and it is not possible to send the
release command, the battery back-up system is activated. At this point, an in-built
timer starts a countdown, and after a predetermined period—if connection is not
re-established—this will issue a command to release the fish. The novel ERFT
system provides full control over the ability to release and makes it
practically impossible to get stuck or add more fish.
The Wellgrab ERFT (Fig. 2) has a bi-directional
motor, and when this is run in a standard manner, it is in a passive mode. The
bi-directional capability enables the development of new methodologies and new
tools, where the motor is utilized to actually engage the fish. In this manner,
there is a wealth of feedback available, such as power consumption, and
millimetre precision with regards to the positioning of the motor. It is also
possible to monitor parameters, such as temperature, as well as movements or
vibrations, via an inbuilt accelerometer.
AN EFFECTIVE SOLUTION
In one instance, a Norwegian
Continental Shelf operator had a parted tool string with a stuck mill bit that had
been left downhole during a scale milling operation. With several complexities
to the fishing operation, including the level of required gripping force needed
to attack the limited fishing point available on the fish, conventional tools
on the market would not be able to complete the job. So, the well was abandoned
temporarily. By combining the Wellgrab (Fig. 2) with Welltec's Well
this instance offering up to 33,000 lbs pulling capability and surface readout
(SRO), a more technical approach to fishing was delivered.
The available engagement length of
the fish was only 29 mm, but thorough systems integration testing confirmed
that the tool would be able to hold the fish while the Well Stroker applied
pulling force. Wellgrab presented a sequence of solutions with a broad range of
grapples and spears to account for different scenarios regarding the possible
outcome; special emphasis was made on several contingency solutions, in case
the fish parted during the operation.
Other complexities, such as wellbore
fill, deviation and alignment of the fish were identified and mitigated as part
of a special risk assessment, whereupon adjustments were made to optimise
correct engagement of the tool onto the fish. First, debris was removed from
the wellbore over several runs, using Welltec´s Well Cleaner with Reverse
Circulating Bit (RCB), Power Suction Tool (PST) and Heavy Debris Removal (HDR).
Access to the fish was confirmed by running a lead impression block, where the
top of the fish was clearly visible.
On the fishing run itself, the first
attempt revealed a bent finger on the grapple, which indicated access to the
fish but a limited wellbore internal diameter. After modelling the findings,
the outside diameter of the bell guide was machined down, to allow the tool to
access the fish. Following this simple adjustment, the Wellgrab ERFT (Fig. 2)
successfully engaged the fish, and with force applied by the Well Stroker, the
fish was retrieved to the surface.
By providing real-time information on
tool performance, the operation was greatly enhanced, and it was carried out
more rapidly and efficiently, in comparison to conventional fishing options.
have been made
available in North America, the North Sea, West Africa and the Middle East, where the solution has
overcome multiple complexities, such as wellbore fill, deviation and alignment
of fish, to complete fishing operations that would not otherwise have been
possible on e-line. WO
V.P., Sales & Marketing, at Welltec. He
has a background in mechanical engineering and has
worked in the oilfield services industry for 23 years. He has extensive
experience in wireline operations, operations management and sales &
KRISTIANSEN is CEO at Autentik. He has broad
experience as a well specialist and extensive knowledge of the wireline
business segment. His 25 years of industry experience include leading
roles in Operations and Business Development, and as CEO of Autentik for the
last two years, specializing in the digital transition of fishing solutions.