Piper Alpha and the Evolution of Inherently Safe Design and Integrity Management: An Overview of Interpretations and Lessons Learned

2010 ◽  
Author(s):  
Binder Singh ◽  
Paul Jukes ◽  
Bob Wittkower ◽  
Ben Poblete
Keyword(s):  
Life Cycle ◽  
North Sea ◽  
Lessons Learned ◽  
Monitoring And Control ◽  
Related Case ◽  
The North ◽  
Modes Of Failure ◽  
Integrity Management ◽  
And Performance ◽  
The Uk

The development of Inherently Safe Design, Corrosion and Integrity Management as a genuine combined engineering discipline has evolved largely over the past 30 years or so, with significant acceleration and urgency after the Piper Alpha offshore disaster in the North Sea in 1988. The concepts and practices have matured with many significant changes implemented across the world offshore regions. Even after more than 20 years, the emanating point for sweeping changes has been the Cullen Report and the UK North Sea industry. This paper offers an interpretation of the early and later lessons learned, as applicable and relevant to deepwater and by analogy arctic offshore assets and pipelines, whereupon conditions are harsh and accessibility very limited. The particular focus is on the so called ‘secondary tier’ points related to materials performance, corrosion, and integrity; the understanding monitoring and control of such matters and failures can be critical in reconstituting integrity, if pragmatic life cycle safety and performance are to be recognized. It is argued that modes of failure such as those related to loss of material properties, corrosion, erosion, environmental cracking, and other degradation phenomena, have become far more critical in deepwater and arctic projects. This is mainly due to repair, retrofit, or re-habilitation being invariably far too costly if not virtually impossible in practice. The authors’ use career wide experiences post Piper Alpha to highlight the worries and concerns offering rational pragmatic solutions, illustrated through related case histories. Conclusions and recommendations are based on predictions, interpretations, and viable solutions. Additionally, industry disconnects between technology transfer under this tutelage are identified. The new methods of ‘concurrent design’ and inherently safe design are discussed, and in the context of mechanical, materials, and corrosion engineering advances are related to the use of Key Performance Indicators (KPIs) and Key Failure Indicators (KFIs), for best life cycle integrity and knowledge management. This approach is considered very important for deepwater and arctic assets where ‘surprise’ failures, environmental and political ‘snafus’ are not really an option, and thus more purposeful design investment at CAPEX is vital rather than at OPEX, and the ‘gray’ zone between the two cost centers must be therefore be better reconciled, perhaps it is argued through the concept of an extended CAPEX.

Successful Application of Managed Pressure Drilling MPD Technology to Reach TD in a Narrow Margin HPHT Well in the North Sea – A Case History

2021 ◽  
Author(s):  
Babar Kamal ◽  
Emil Stoian ◽  
Graeme MacFarlane
Keyword(s):  
Pore Pressure ◽  
North Sea ◽  
Back Pressure ◽  
Lessons Learned ◽  
The North ◽  
Pull Out ◽  
Bottom Hole ◽  
Managed Pressure Drilling ◽  
Integrity Tests ◽  
Remedial Work

Abstract This paper reviews the recently concluded successful application of a Managed Pressure Drilling (MPD) system on a High-Pressure High-Temperature (HPHT) well with Narrow Mud Weight Window (NMWW) in the UK sector in the Central North Sea. Well-A was drilled with the Constant Bottom Hole Pressure (CBHP) version of MPD with a mud weight statically underbalanced and dynamically close to formation pore pressure. Whilst drilling the 12-1/2" section of the well with statically under-balanced mud weight, to minimize the overbalance across the open hole, an influx was detected by the MPD system as a result of drilling into a pressure ramp. The MPD system allowed surface back pressure to be applied and the primary barrier of the well re-established, resulting in a minimal influx volume of 0.06 m3 and the ability to circulate the influx out by keeping the Stand Pipe Pressure (SPP) constant while adjusting Surface Back Pressure (SBP) through the MPD chokes in less than 4 hours with a single circulation. After reaching the 12-1/2" section TD, only ~0.025sg (175 psi) Equivalent Mud Weight (EMW) window was available to displace the well and pull out of hole (POOH) the bottom hole assembly (BHA) therefore, 3 × LCM pills of different concentrations were pumped and squeezed into the formation with SBP to enhance the NMWW to 0.035sg EMW (245 psi) deemed necessary to kill the well and retrieve BHA. MPD allowed efficient cement squeeze operations to be performed in order to cement the fractured/weak zones which sufficiently strengthened the well bore to continue drilling. A series of Dynamic Pore Pressure and Formation Integrity Tests (DPPT and DFIT) were performed to evaluate the formation strength post remedial work and to define the updated MMW. Despite the challenges, the MPD system enabled the delivery of a conventionally un-drillable well to target depth (TD) without any unplanned increase/decrease in mud weight or any costly contingency architecture operations, whilst decreasing the amount of NPT (Non Productive Time) and ILT (Invisible Lost Time) incurred. This paper discusses the planning, design, and execution of MPD operations on the Infill Well-A, the results achieved, and lessons learned that recommend using the technology both as an enabler and performance enhancer.

Significant Performance Improvement with MPD in HPHT Narrow Drilling Window Campaign in the North Sea

2021 ◽  
Author(s):  
Babar Kamal ◽  
Abdul Saboor ◽  
Graeme MacFarlane ◽  
Frank Kernche
Keyword(s):  
Precise Determination ◽  
Lessons Learned ◽  
Overburden Pressure ◽  
The North ◽  
Fracture Pressure ◽  
Open Hole ◽  
Infill Drilling ◽  
Significant Performance ◽  
And Performance ◽  
Formation Pore Pressure

Abstract Significant depletion in reservoir pressure, huge uncertainties in pore and fracture pressure, high overburden pressure on top of reservoir, Narrow Mud Weight Window (NMWW) and Partial/Total losses whilst entering the reservoir made these HPHT (High Pressure High Temperature) wells conventionally un-drillable. Due to these substantial challenges these wells were considered not only costly but also carry a high probability of failure to reach well TD (Total Depth). MPD (Managed Pressure Drilling) is a safer and more effective drilling technique as compared to conventional drilling, especially in wells with NMWW and downhole hazards. The precise determination and dynamic downhole pressure management was imperative to complete these wells without well control incidents. The Constant Bottom Hole Pressure (CBHP) variant in combination of automated MPD system was deployed with a mud weight statically underbalanced while dynamically managed above formation pore pressure to minimize the overbalance across the open hole. MPD enabled the operator to efficiently navigate Equivalent Circulation Density (ECD) through the pore and fracture pressure window, allowed significant improvements throughout the entire campaign. This paper discusses the challenges faced during the last three wells drilled in the campaign which includes equipment issues, commissioning delays, losses whilst drilling, Managed Pressure Cementing (MPC), 7" drill-in-liner and plugged/blocked lines due to weather and mud conditions. The paper describes HPHT infill drilling experience, specific techniques, practices as well as lessons learned from each well during the campaign were implemented to address challenges and to improve performance. The MPD system commissioning was optimized by repositioning the lines which saved significant critical rig time. The blowdown points were added on the lines that were not operational continuously therefore a procedure was developed for flushing to avoid plugging. Optimized drilling strategy was also developed where MW was further reduced to avoid losses as observed in previous wells and CBHP was maintained by manipulating Surface Back Pressure (SBP) from surface. This paper also discusses continuous improvements /upgrades in MPD operating software which assisted the operator in accurate monitoring of flow, SBP and BH-ECD to save significant rig cost in terms of invisible Non-Productive Time (NPT). MPD is a drilling enabler and performance enhancer which saved 80 days of Authorization for Expenditure (AFE) on this challenging HPHT campaign.

Integrated Decommissioning of a Pentagon Shaped Production Semisubmersible in the UK: A Unique Challenge

2018 ◽  
Author(s):  
Luis F. Batalla Toro ◽  
Simon L. Reid ◽  
Alfredo Salcines Tudela ◽  
Duncan Graham
Keyword(s):  
Lessons Learned ◽  
Production Unit ◽  
Original Design ◽  
Successful Operation ◽  
Unique Challenge ◽  
The North ◽  
Sequence Of Events ◽  
The North Sea ◽  
Drilling Rigs ◽  
The Uk

Between 1969 and 1977, eleven semisubmersible drilling platforms were designed and built with an innovative pentagon shaped hull, specifically to work in the harsh environment of the North Sea. One of the drilling rigs, the Alexander L. Kielland, was converted soon after construction into an accommodation platform (flotel) and failed catastrophically in 1980. Another, the Pentagon 83 “Drillmaster” (renamed as Buchan Alpha), was being converted to a Floating Production Unit at the time of the disaster. The structure of Buchan Alpha was significantly modified during the conversion of the platform so that it benefited from the lessons learnt following the Alexander L. Kielland accident to ensure that the same sequence of events could not be repeated. This technical paper objective is to explain the integrated decommissioning process of the Buchan Alpha in the UK after more than 40 years since being built and more than 35 years of successful operation since it was converted to a Floating Production Unit, and how the features of its original design have accompanied the platform through the decommissioning process. The scope covers all phases of Buchan Alpha decommissioning from the detailed planning and preparation, the suspension of production up to the dismantling and recycling process. Significant challenges for the decommissioning team included the requirement to preserve the operational status of the subsea infrastructure for potential future field redevelopment and the diver disconnection of the subsea wells. Buchan Alpha’s deep draught presented limitations on the selection of dismantling and recycling yards due to quayside water depths. Complex ballasting operations and removal of the thruster’s propellers were required to facilitate the platform berthing at the quayside. Key lessons learned applicable for future decommissioning of floating production facilities will be shared.

Towards a vulnerability assessment of the UK and northern European coasts: the role of regional climate variability

2005 ◽  
Vol 363 (1831) ◽  
pp. 1329-1358 ◽  
Author(s):  
M.N Tsimplis ◽  
D.K Woolf ◽  
T.J Osborn ◽  
S Wakelin ◽  
J Wolf ◽  
...  
Keyword(s):  
Sea Level ◽  
Wave Height ◽  
North Sea ◽  
Positive Response ◽  
Sea Level Change ◽  
Empirical Relationships ◽  
Level Change ◽  
The North ◽  
The North Sea ◽  
The Uk

Within the framework of a Tyndall Centre research project, sea level and wave changes around the UK and in the North Sea have been analysed. This paper integrates the results of this project. Many aspects of the contribution of the North Atlantic Oscillation (NAO) to sea level and wave height have been resolved. The NAO is a major forcing parameter for sea-level variability. Strong positive response to increasing NAO was observed in the shallow parts of the North Sea, while slightly negative response was found in the southwest part of the UK. The cause of the strong positive response is mainly the increased westerly winds. The NAO increase during the last decades has affected both the mean sea level and the extreme sea levels in the North Sea. The derived spatial distribution of the NAO-related variability of sea level allows the development of scenarios for future sea level and wave height in the region. Because the response of sea level to the NAO is found to be variable in time across all frequency bands, there is some inherent uncertainty in the use of the empirical relationships to develop scenarios of future sea level. Nevertheless, as it remains uncertain whether the multi-decadal NAO variability is related to climate change, the use of the empirical relationships in developing scenarios is justified. The resulting scenarios demonstrate: (i) that the use of regional estimates of sea level increase the projected range of sea-level change by 50% and (ii) that the contribution of the NAO to winter sea-level variability increases the range of uncertainty by a further 10–20 cm. On the assumption that the general circulation models have some skill in simulating the future NAO change, then the NAO contribution to sea-level change around the UK is expected to be very small (<4 cm) by 2080. Wave heights are also sensitive to the NAO changes, especially in the western coasts of the UK. Under the same scenarios for future NAO changes, the projected significant wave-height changes in the northeast Atlantic will exceed 0.4 m. In addition, wave-direction changes of around 20° per unit NAO index have been documented for one location. Such changes raise the possibility of consequential alteration of coastal erosion.

Movements and distribution of cod (Gadus morhua) in the southern North Sea and English Channel: results from conventional and electronic tagging experiments

2007 ◽  
Vol 87 (2) ◽  
pp. 599-613 ◽  
Author(s):  
David Righton ◽  
Victoria Anne Quayle ◽  
Stuart Hetherington ◽  
Gary Burt
Keyword(s):  
North Sea ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
English Channel ◽  
Seasonal Movement ◽  
Southern North Sea ◽  
The North ◽  
Fisheries Policy ◽  
The Uk ◽  
Electronic Tags

The sub-structure of Atlantic cod (Gadus morhua) stocks in the North Sea has important consequences for fisheries management as the Common Fisheries Policy moves towards a more regional approach. We investigated the movements, distribution and behaviour of cod in the southern North Sea (ICES IVc) and English Channel (ICES VIId) by re-analysing historic data from conventional tagging experiments, and by conducting new experiments with electronic tags. Cod tagged and released in IVc showed a northwards shift in distribution during the feeding season consistent with a homing migration away from spawning grounds along the coasts of the UK and the Netherlands. In contrast, cod tagged and released in VIId did not exhibit a consistent pattern of seasonal movement. Many cod released in VIId were subsequently recaptured close to their release position, although some moved out of the Channel and into the southern North Sea. Overlap between the recapture areas of cod released in the different management areas was no more than 25% in either the spawning or feeding season. Behavioural data from electronic tags suggest that cod in IVc make use of tidal streams to migrate northwards and eastwards in spring, whereas selective tidal stream transport was rarely exhibited by cod tagged and released in VIId. Overall, the evidence suggests that there are behavioural differences between cod in IVc and VIId that limit the mixing of cod from these two areas during the feeding and spawning seasons.

The Leman Field, Blocks 49/26, 49/27, 49/28, 53/1, 53/2, UK North Sea

2003 ◽  
Vol 20 (1) ◽  
pp. 761-770 ◽  
Author(s):  
A. P. Hillier
Keyword(s):  
North Sea ◽  
Gas Field ◽  
Dune Sands ◽  
The North ◽  
The North Sea ◽  
To Come ◽  
The Uk

AbstractDiscovered in 1966 and starting production in 1968, Leman was the second gas field to come into production in the UK sector of the North Sea and is still producing gas today. It is classified as a giant field with an estimated initial gas-in-place of 397 BCM of gas in the aeolian dune sands of the Rotliegend Group. The field extends over five blocks and is being developed by two licence groups with Shell and Amoco (now BP Amoco) being the operators

Cold Induced Abnormal Catches of Sole

1998 ◽  
Vol 78 (1) ◽  
pp. 345-347 ◽  
Author(s):  
J.W. Horwood ◽  
R.S. Millner
Keyword(s):  
North Sea ◽  
Cold Water ◽  
The South ◽  
Total Allowable Catch ◽  
The North ◽  
Solea Solea ◽  
The North Sea ◽  
The Uk ◽  
The Eu ◽  
Made In

Large catches of sole (Solea solea) were made in early 1996 from the south-western North Sea. Sole suffer physiological damage in waters below 3–4 C. In February 1996 cold water of 3–4 C unusually extended from the Continental coast onto the Dogger Bank. It is likely that the increased catches were due to the consequential distribution and behaviour of the sole, making them more susceptible to capture.Exceptionally large catches of mature sole (Solea solea (L.)) were made in February 1996 by Lowestoft fishermen from the south-western North Sea. Surprisingly this was not welcome. The UK allocation of the North Sea sole is -4 % of the EU Total Allowable Catch (TAC), and fishermen are restricted nationally, and by the fishing companies, to a tightly managed ration. The Lowestoft Journal (8 March 1996) reported the suspension of a local fishing skipper for not throwing back 5000 kg of sole caught in the Silver Pits. We will show that the abnormal catches were due to exceptionally cold waters.Sole in the North Sea are at the northern extremity of their range, with sole seldom living in waters below 5°C (Horwood, 1993). In fact, North Sea sole were successfully introduced into Lake Quarun, Egypt, where they lived in temperatures in excess of 30°C (El-Zarka, 1965). Young sole migrate from their shallow inshore nursery grounds, such as the Waddensea, as winter approaches (Creutzberg & Fonds, 1971).

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