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Abstract
A novel timer activated sandface valve was developed that has significant
impact on wellbore productivity by enabling improved wellbore clean up,
particularly in high angle and open hole completions. This technology has been
field trialled and proven in three wells in a North Sea field. The tool was
developed from concept to installation in less than nine months including
detailed engineering review and assurance.
Negative impact to productivity due to inefficient wellbore clean up of high
angle completions is a common situation for production wells. The current
solution can be complex completion architecture or extensive clean up
procedures that are both expensive and difficult to implement. The consequence
of a poor clean up can be loss in well productivity, access to reserves or a
requirement to sidetrack the well.
Poor clean up was observed in several wells in a North Sea field. The wells
exhibited high skin and no flow from the toe sections of the well due to the
dominance of high productive intervals subject to high drawdown at the heel of
the well. The timer activated sand face valve was developed with the key
objective to deliver sequential clean up from the toe of the reservoir section
without intervention or incremental rig time. The valves also deliver the
functionality of a sliding side door for future water shut-off capability along
the well bore.
The paper will present an overview of the technical challenge, detail
development of the tool and processes used for assurance and include results of
the field trial. The valve development combines a field proven timer activation
mechanism with conventional sliding sleeve technology. The tool was developed
without incremental resource and cost often required for product development
utilising specifically designed lean technical assurance tools and failure mode
and effects analysis processes. The result is a successfully field proven
completion tool that is the basis for a new completion technique that has
application in high angle wells in all oilfield applications.
Introduction
The project to design, develop, manufacture and install a novel timer
activated valve was initiated in response to poor clean up observed in wells
drilled in a North Sea development. Flow contribution from wells drilled in the
field had been restricted to small sections of the wellbore. This was
determined by pressure transient analysis and confirmed by results of
production logging. The flow was shown to be coming predominantly from the heel
of the well and in some cases the flowing length was less than 20% of the
overall reservoir section drilled. Log data acquired during drilling, and data
gathered from offset appraisal wells showed that the wells were capable of
producing from the entire section. Considerable value in terms of increased
production and reservoir access could be gained if the wells could be designed
or modified to increase the flowing interval.
Analysis of conventional and established techniques for improving clean up
in open hole wells was undertaken. Poor clean up of high angle wells,
particularly with open hole completions is common. Despite poor clean up, the
wells drilled in the field were high rate producers. The aim was to establish
the most cost effective method of increasing the flowing interval without
risking base production. Remedial techniques were also investigated and a trial
was conducted of most appropriate selected intervention. This was not
successful in improving production and resulted in a collapsed wellbore.
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