Operational Challenges for Drilling Shallow Water Wells With Dynamically Positioned Rigs

2020 ◽  
Author(s):  
Rohit Vaidya ◽  
Mahesh Sonawane
Keyword(s):  
Shallow Water ◽  
Weak Link ◽  
Mitigation Options ◽  
Drilling Rig ◽  
Water Wells ◽  
Fatigue Monitoring ◽  
Drilling Operations ◽  
Drilling Rigs ◽  
New Generation ◽  
Selection Of

Abstract Traditionally, shallow water wells have been drilled from fixed platforms, jack-ups or moored drilling rigs. Recently there has been increased interest in performing operations on these wells using new generation of Dynamically Positioned (DP) rigs, driven by available capacity of these rigs and environmental regulations that restrict laying anchors on the seabed. Shallow water offshore drilling operations present a set of unique challenges and these challenges are further amplified when operations are performed on older wells with legacy conductor hardware with newer DP vessels and larger BOPs. The objective of the paper is to present challenges that occur during drilling in shallow water and discuss mitigation options to make these operations feasible through a series of case studies. Key challenges to optimizing riser operability and rig uptime are discussed. Potential modifications to the upper riser stack-up and rig deck structure for maximizing operational uptime are discussed. Riser system weak point assessment is presented along with solutions for mitigating risks in case the wellhead or conductor structural pipe is identified as the weak link. Selection of the drilling rig can have significant impact on wellhead fatigue response. Some criteria for rig selection based on drilling riser and wellhead system performance is presented with the objective of optimizing the fatigue performance of the wellhead and conductor system. Wellhead fatigue monitoring solutions in combination with physical fatigue mitigation options are presented to enable operations for fatigue critical wells.

The Influence of Drilling Rig and Riser System Selection on Wellhead Fatigue Loading

2012 ◽  
Author(s):  
John F. Greene ◽  
Dara Williams
Keyword(s):  
Fatigue Life ◽  
Shallow Water ◽  
Deep Water ◽  
Fatigue Loading ◽  
Careful Consideration ◽  
Drilling Rig ◽  
Drilling System ◽  
Drilling Rigs ◽  
Water Depths ◽  
Selection Of

With drilling and exploration activity currently high in both deep and shallow water regions rig availability and selection is an issue for operators to consider in order to achieve the desired exploration schedule. At present the industry focus is on the development of 6th generation drilling rigs with the capacity to operate in increasing deep water. However despite the focus on deepwater exploration and the associated demand for deepwater drilling rigs there still exists demand for drilling rigs that can operate in shallow to moderate water depths (100m–500m). In addition, certain field development scenarios may exist where planned water depths for drilling activities vary significantly and therefore a drilling rig and riser system is required that can operate satisfactorily in both shallow and deep water depths. For a given drill site, rig availability or well location, may be such that an operator may have to select a modern deepwater 6th generation rig for shallow water activities where a 3rd generation rig would appear to provide a better solution. Other considerations such as vessel station keeping requirements may lead to selection of a 6th generation rig over a 3rd generation rig, as the former tend to have improved DP thrusters capacity. However it is also important to note that while the 6th generation rigs may have been proven to be robust systems for operation in deep water, the response of a 6th generation drilling system in shallow water depths can be very different to that of an older 3rd generation rig and drilling riser system. Thus careful consideration must be made by the operator when considering the selection of drilling vessels for shallow to moderate water depths. Fatigue life of the wellhead is shown to be affected when one compares the response of the 6th generation and 3rd generation drilling systems in shallow to moderate depths. This also needs to be accounted for when selecting rigs for workover or intervention operations on older infrastructure. This paper presents a discussion on the various parameters such as BOP stack size, riser, flex joint and vessel design that influence the response of the drilling system in shallow to moderate water depths (100m–500m). A number of case studies and parametric studies have been carried out and the results of these are presented in order to compare the wellhead fatigue damage from the older 3rd generation systems with the 6thgeneration systems and also to identify the critical drivers for this fatigue life reduction.

Innovative Ice Protection for Shallow Water Drilling: Part I — Presentation of the Concept

2006 ◽  
Author(s):  
Arne Gu¨rtner ◽  
Ove Tobias Gudmestad ◽  
Alf To̸rum ◽  
Sveinung Lo̸set
Keyword(s):  
Shallow Water ◽  
Shallow Waters ◽  
Drilling Rig ◽  
Modular Concept ◽  
Drilling Operations ◽  
Drifting Ice ◽  
Ice Impacts ◽  
Jack Up ◽  
Near Future ◽  
Ice Period

Recent discoveries of hydrocarbons in the shallow waters of the Northern Caspian Sea arise the need for intensive drilling activities to be carried out in the near future in order to explore the potentials. Experience with mobile drilling units in the seasonally ice infested waters solely originates from the current drilling campaign of the Sunkar drilling barge at Kashagan and Kalamkas. However, with increased drilling activities upcoming, innovative drilling concepts are desirable due to the objective of maintaining drilling operations during the ice period with conventional non-ice-resistant drilling platforms. Hence, this paper suggests the employment of external Shoulder Ice Barriers (SIBs) to protect a conventional jack-up drilling rig from the hazards of drifting ice in shallow water. The SIB’s design is suggested to increase the ice rubble generation at the ice facing slope and thereby provide sufficient protection from drifting ice impacts. The modular concept of the SIB makes it possible to deploy each module in a floating mode to site, whereupon they are ballasted and connected to each other, forming a sheltered position for the jack-up. Subsequent to the termination of the drilling campaign the SIB modules may be retrieved by de-ballasting and tow out, without having significant impact on the environment. This paper presents, on a technical feasible level, the concept of ice protection in shallow water by means of SIBs.

Optimisation of Conductor System Design to Minimise Wellhead Fatigue Issues

2013 ◽  
Author(s):  
Dara Williams ◽  
Kevin Purcell
Keyword(s):  
System Design ◽  
Shallow Water ◽  
Water Depth ◽  
Fatigue Loading ◽  
Recent Experience ◽  
Water Wells ◽  
Increased Risk ◽  
Main Driver ◽  
Drilling Rigs ◽  
Water Depths

Current market trends in the construction of newbuild drilling rigs indicate that the market is driven by demand for ultra-deepwater capacity semi-submersible rigs and drillships. These drilling vessels have capacity to drill in water depths of up to 12,000ft and possibly beyond in the near future. With increase in water depth capacity, more complex and heavier BOP stacks are required. Many modern drilling vessels are now incorporating BOPs with capacities of 20ksi pressure and up to 7 shear/seal rams incorporated. This leads to increased height and weight in the BOP. Whilst newbuild drilling vessels will be required to operate in water depths from 1,500ft to 12,000ft whilst on DP mode, deepwater semi-submersible drilling rigs will also have capability for operation in water depths <1,500ft using conventional mooring. Recent experience with modern deepwater rigs with large BOP stacks in water depth of 1,500ft or less suggests increased risk of fatigue when compared to 3rd generation rigs. If future trends continue with larger BOP stacks being designed then the problem of wellhead fatigue with modern deepwater drilling vessels is likely to become more acute. As noted in previous studies the water depth at drillsite has a major impact on the level of fatigue accumulated in the wellhead system. The main driver for this has been found to be the height and weight of the BOP. With requirements for newbuild drilling rigs for 12,000ft water depth capacity being the industry norm, and with increased requirements for BOP functionality, the gap between wellhead loading from 3rd generation and 6th generation rigs is widening. Given that many 3rd generation rigs will likely be decommissioned in the coming years then the usage of 6th generation rigs for shallow water operations will only become more commonplace due to rig availability. Thus, unless market conditions dictate the construction of smaller and lighter BOP stacks, the design of shallow water wells will be critical to ensure fatigue loading on the wellhead and conductor is kept to a minimum. This paper presents a summary of the results of a series of parameter studies carried out to assess a range of options for optimisation of casing and conductor design for 6th generation rigs in shallow water. Various recommendations are made as part of this study as to the addition of supplemental casing and conductor strings of varying sizes and wall thickness to ensure a robust conductor system design for fatigue performance.

ESP and Completion Deployment using Dual Derrick Drill Ship Rigs

2021 ◽  
Author(s):  
Daniel Lemos ◽  
Jean Marins ◽  
Raone De Lima
Keyword(s):  
Deep Water ◽  
Process Development ◽  
Safety Concern ◽  
Drilling Rig ◽  
Equipment Reliability ◽  
Water Wells ◽  
New Process ◽  
Electrical Submersible Pumps ◽  
Drilling Operations ◽  
Intervention Costs

Abstract This paper presents an innovative concept to run Electrical Submersible Pumps (ESP) and upper completion utilizing dual derrick drillship rigs in deep water wells. The availability of a second deck to assemble, test and rack long assemblies brings the possibility to conduct a safer, efficient and reliable operation. The experience in Brazil running complex completions and high horsepower ESPs shows how important is to implement initiatives to reduce rig time. The main objective of the new process is to have every completion tool readily available in the drilling deck, requiring minimum time to connect it to the completion string. In the standard process, the tool sits in the pipe deck until completion string reaches its set position and only then the equipment is brought into the rig floor to be serviced and made up to the completion string. The methodology to assemble ESP and completion tools offline in the auxiliary derrick was developed in partnership with the operator, the service company, and the drilling rig contractor. The offline preparation concept was considered as part of the completion design phase analyzing every step of the upper completion run, looking for efficiency improvement and reduced total rig time. The modern automated pipe handling system was used to manipulate the long and heavy assemblies from the auxiliary deck to the racking system and from the racking system to the main deck without any safety concern, and with minimal human intervention. Eight deep-water operations were completed in Brazil using the new concept and the results brought important rig time reduction in the upper completion running time. The tools that were part of the completion included DHSV, permanent downhole gauges, chemical injection valves, 1600 HP ESP system and tubing test valves. The new process allows the team to service equipment without the usual operation rush reducing installation related failure therefore increasing equipment reliability. The methodology presented on this paper contributes to oil industry as a field-proven reference for offshore ESP and completion deployment technique reducing HSE exposure and total well construction cost. This is particularly important for deep and ultra-deepwater projects which are associated with high intervention costs. Dual derrick rigs were designed with focus to improve drilling operations and after the new process development, the modern robotized machinery empowers ESP and completion activities with improved efficiencies.

Instrumented Wellhead Load Relief System for Shallow Water Arctic Conditions: Paper 1 — System Design, Installation and Preliminary Results

2018 ◽  
Author(s):  
Scott Benson ◽  
Massimiliano Russo ◽  
Eivind Rasten ◽  
Ward Avery ◽  
Paul LeGrow ◽  
...  
Keyword(s):  
Shallow Water ◽  
Data Gathering ◽  
Processing System ◽  
Field Extension ◽  
Grand Banks ◽  
Oil Companies ◽  
Drilling Rig ◽  
Load Relief ◽  
Drilling Operations ◽  
High Level

In recent years, lower oil prices have forced many oil companies to reduce capex costs by revitalizing brown fields, rather than developing new green fields. At the same time, the offshore drilling rig market has seen many old rigs, typically used for shallow water operations, being scrapped, leaving new generation, deep and ultra-deep water MODUs as the only viable option for new drilling campaigns. Based on the above, wellhead fatigue on older assets, especially in harsh, shallow water environments, has started to gain a central role during the planning phases of workover and intervention operations. In recent years, Suncor Energy began investigating an extension to its Terra Nova field, which began production in 2002. The field uses subsea wells tied back to an FPSO which is moored in 95m of water off Canada’s eastern Grand Banks, an area frequented by icebergs. Drilling operations for the field extension were planned to commence in summer 2017, and continue with a year-round drilling campaign using a Cat 6 MODU. Since the extension would involve sidetracks and interventions from existing wellheads, a series of wellhead fatigue studies were undertaken using a variety of industry recognized methodologies [1] to understand the levels of fatigue accumulation. Although there has been no evidence of wellhead fatigue damage, Suncor chose to take a very prudent and proactive approach, aimed at minimizing fatigue, and maintaining fatigue life for potential future drilling operations. An Instrumented Wellhead Load Relief (iWLR) system was installed, which is designed to restrain BOP motions, thereby reducing the wellhead loads considerably. The load reduction system virtually eliminates additional fatigue accumulation for the planned operations. Additionally, the instrumentation system enables the precise monitoring and tracking of loads applied at the wellhead for future analysis. This paper describes the engineering challenges needed to develop and install the iWLR system in a harsh, shallow water, arctic environment. This area is characterized by very stiff soils pitted with iceberg scours, where subsea equipment must be protected within 10m deep excavated drill centers to prevent iceberg collisions in the relatively shallow water. Additionally, the paper describes how the instrumentation system was integrated with the BOP MUX cable communication system, for the first time, to enable real time monitoring of BOP motions using high accuracy gyroscopes and load cells which monitor dynamic iWLR tether forces. A topside data gathering and processing system was developed to present wellhead loads based on the indirect method, with new algorithms established to account for the tether forces. Finally, the paper presents some preliminary high-level results, showing the efficiency of the system based on measured data.

GOODWYN ‘A’ DRILLING FACILITIES

1993 ◽  
Vol 33 (1) ◽  
pp. 343
Author(s):  
Derek C. Morrow ◽  
Nick E. Jackson
Keyword(s):  
Modular Design ◽  
High Capacity ◽  
Cost Savings ◽  
High Standard ◽  
Drilling Rig ◽  
Contract Administration ◽  
Modular Concept ◽  
Drilling Operations ◽  
Drilling Rigs ◽  
Safety Systems

The Drilling Facilities Package designed and developed by Atwood Oceanics Australia Pty. Ltd. for operation on Woodside Offshore Petroleum Pty. Ltd.'s Goodwyn 'A' Platform will break new ground in the development and application of offshore modular drilling rig technology when commencement of offshore drilling is achieved. These facilities are among the largest, specifically designed, offshore demountable drilling rigs in the world today.Initially, Woodside performed sufficient engineering to determine a design specification for the Drilling Facilities which detailed the types of equipment necessary and the final performance characteristics required by the finished facility to drill the Goodwyn 'A' production wells.Following award of the Drilling Facilities Contract to Atwood Oceanics in 1989, Woodside's role was essentially related to technical interface and contract administration management. The responsibility for the design, fabrication, commissioning and operation of the Drilling Facilities lay with Atwood Oceanics.The Drilling Facilities consist of fifty-two (52) small modules, each weighing up to 105 tonne. These modules are assembled into three (3) major structural packages, these being the Drilling Support Facilities, weighing some 1300 tonne, the Sub-Base weighing 1100 tonne and the Derrick weighing 260 tonne. Total operating weight of the facilities will exceed 4500 tonne.The modular design of these facilities was developed by Atwood Oceanics from previous modular rig design of relatively simple facilities and technical scope, up to the high capacity, technical complexity and flexibility in design demanded for operation on the Goodwyn 'A' Platform. Following the issue of the Cullen Report on the Piper Alpha Disaster, extensive control and monitoring safety systems were included in the design. These systems have had an adverse impact on the modular concept due to the large increase in electrical interfaces, however the modular concept remains sound and viable.Modular rig design has allowed a Drilling Facility to be developed which has accrued savings in design, fabrication, fit-out, transport and installation and has resulted in reduced overall installed weight. These savings are real and demonstrable when compared with conventional large-module drilling rig packages of similar scope and complexity. Unlike its North Rankin 'A' development, Woodside elected to have the Drilling Facilities for Goodwyn 'A' designed, procured, fabricated and commissioned by an experienced drilling contractor, who will then operate and maintain the rig during the drilling phase (P.Scott et al., 1991). Woodside will realise substantial cost savings at the point when the facilities are installed and ready to drill. Further savings will accrue during drilling operations by allowing the drilling contractor more autonomy and responsibility (eg. maintenance of the complete drilling facilities will be by contractor personnel).The relative ease of removal of the facilities and potential for re-use on other installations will generate additional significant cost benefits in the future.The Drilling Facilities are state-of-the-art in their applied technology and are capable of year-round, self-contained operation for the drilling of highly deviated, long reach wells of up to 72° deviation from the vertical and up to 7000 m along hole depth.This paper provides an overview of the design, fabrication, fit-out, onshore commissioning, transport and installation of the modules which comprise the Goodwyn 'A' Drilling Facilities, for which Atwood Oceanics were awarded a Commendation for a High Standard of Engineering Achievement at the Institution of Engineers, Australia 1992 Engineering Excellence Awards.

Bifluoride Ion Mediated SuFEx Trifluoromethylation of Sulfonyl Fluorides and Iminosulfur Oxydifluorides

2018 ◽  
Author(s):  
Christopher J. Smedley ◽  
Bing Gao ◽  
Suhua Li ◽  
Qinheng Zheng ◽  
Andrew Molino ◽  
...  
Keyword(s):  
Breast Cancer Cells ◽  
Catalytic Mechanism ◽  
Bioactive Molecules ◽  
Chromatographic Purification ◽  
Rapid Exchange ◽  
Nucleophilic Displacement ◽  
Sulfur Fluoride ◽  
Reactions With Nucleophiles ◽  
New Generation ◽  
Selection Of

Sulfur-Fluoride Exchange (SuFEx) is the new generation click chemistry transformation exploiting the unique properties of S-F bonds and their ability to undergo near-perfect reactions with nucleophiles. We report here the first SuFEx based protocol for the efficient synthesis of pharmaceutically important triflones and bis(trifluoromethyl)sulfur oxyimines from the corresponding sulfonyl fluorides and iminosulfur oxydifluorides, respectively. The new protocol involves the rapid exchange of the S-F bond with trifluoromethyltrimethylsilane (TMSCF<sub>3</sub>) upon activation with potassium bifluoride in anhydrous DMSO. The reaction tolerates a wide selection of substrates and proceeds under mild conditions without need for chromatographic purification. A tentative catalytic mechanism is proposed supported by DFT calculations, involving formation of the free trifluoromethyl anion followed by nucleophilic displacement of the S-F through a five-coordinate intermediate. The preparation of a benzothiazole derived bis(trifluoromethyl)sulfur oxyimine with cytotoxic selectivity for MCF7 breast cancer cells demonstrates the utility of this methodology for the late-stage functionalization of bioactive molecules.<br>

Instabilities of coupled density fronts and their nonlinear evolution in the two-layer rotating shallow-water model: influence of the lower layer and of the topography

2013 ◽  
Vol 716 ◽  
pp. 528-565 ◽  
Author(s):  
Bruno Ribstein ◽  
Vladimir Zeitlin
Keyword(s):  
Shallow Water ◽  
Nonlinear Evolution ◽  
Lower Layer ◽  
Phase Locking ◽  
Water Model ◽  
Shallow Water Model ◽  
Wave Instability ◽  
Rotating Shallow Water ◽  
New Generation ◽  
Rotating Shallow Water Equations

AbstractWe undertake a detailed analysis of linear stability of geostrophically balanced double density fronts in the framework of the two-layer rotating shallow-water model on the $f$-plane with topography, the latter being represented by an escarpment beneath the fronts. We use the pseudospectral collocation method to identify and quantify different kinds of instabilities resulting from phase locking and resonances of frontal, Rossby, Poincaré and topographic waves. A swap in the leading long-wave instability from the classical barotropic form, resulting from the resonance of two frontal waves, to a baroclinic form, resulting from the resonance of Rossby and frontal waves, takes place with decreasing depth of the lower layer. Nonlinear development and saturation of these instabilities, and of an instability of topographic origin, resulting from the resonance of frontal and topographic waves, are studied and compared with the help of a new-generation well-balanced finite-volume code for multilayer rotating shallow-water equations. The results of the saturation for different instabilities are shown to produce very different secondary coherent structures. The influence of the topography on these processes is highlighted.

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