bluuebunny/crossref_metadata_2025_split huggingface dataset:
We're Stuck: Efficient Casing Removal for Well Abandonment Applications
Authors: Joppe Lambertus C. , Nelson Jonathan F. , Kelman Gary L. 
Published: April 2017

Well abandonment operations represent pure cost to the operator without return on their expenditure. However, to manage future liability, these activities are critically important. Performing them correctly involves detailed planning. Good practice places a permanent barrier across the wellbore in competent cap rock and embeds all tubulars in the cement. Herein lies the main challenge for well abandonment; annular isolation is sometimes compromised or wasn't there from the start (e.g., subsea wells). Addressing these annular isolation issues results in extra steps in the well abandonment process, translating into extra time and money for the operator.
This paper will discuss field-proven, cost-effective solutions for casing removal including reducing the surface footprint or providing a single-trip solution that lowers the overall cost of operation.
Multiple case histories will highlight different challenges, solved by novel ideas and a combination of surface systems and downhole equipment.
Case History 1: 13⅜-in. casing partially stuck in the well needs to be removed, a single cut-and-pull operation was not successful and milling was not an option due to shallow/weak formation and equivalent circulating density (ECD) issues. Advanced milling technology enabled 30 casing cuts in a single trip in short sections, allowing each section to be pulled free using the rig's pulling capacity while minimizing surface handling.
Case Study 2: Platform load capacity or pulling capacity limitations often lead to challenging casing removal operations for slot recoveries and/or permanent well abandonment. Exercising downhole pulling force by anchoring in a larger casing size and utilizing pump pressure instead of overpull enables freeing of pipe with limited surface capabilities. Multiple examples will be shown, including time saved.
Case Study 3: Platform conductor removal operations can be very challenging when the type of connectors cannot carry the full conductor load with inner casing strings. A Rigless solution performing simultaneous operations with the main platform rig, using a sacrificial casing string to pull from the bottom provided a cost-effective solution.
Case Study 4: Platform conductor removal where the conductors have been previously cut and now stand in the water column present challenges of a different kind. The limited platform size led to a casing jacking solution with guide wires that safely and cost-effectively remove the conductors from below the mudline without bringing in a jack-up rig.
A "now what" selection guide at the end of the paper provides an overview of different solutions available, depending on downhole scope of work and the surface capabilities.
Validation of Global Riser/Wellhead Analysis Using Data from a Full-Scale Measurement Campaign
Authors: Agarwal Puneet , McNeill Scot , Bhalla Kenneth , Walker Karen 
Published: April 2017

Fatigue damage predictions of risers and wellhead/casing systems due to drilling operations require predictive modeling techniques for load calculation/estimation. This work attempts to address the uncertainty as to whether the global riser analyses are overly conservative due to model idealizations, analytical assumptions, the use of time- or frequency-domain techniques, and incorporation of certain linear or non-linear behavior. To address these questions, a field measurement program was executed to obtain vessel, riser and stack motions data, which were used to validate analytical models and procedures.
A real-time monitoring system was deployed on a 6th generation semi-submersible mobile offshore drilling unit operating in a shallow water, harsh environment region. Accelerations and angular rates were captured on the Lower Marine Riser Package (LMRP), drilling riser and vessel. The metocean data consisting of measured seastates and full-depth current profiles, as well as riser tensions, mud weights, and vessel offsets were also concurrently recorded. The global models of the riser, wellhead, stack, casing and soils were created using two in-house software, DERP (frequency-domain) and RAMS (both frequency- and time-domain), using "as-designed" input information.
Analytically predicted motions (displacements and rotations) of the LMRP, riser, and vessel were compared with the measured motions. It was found that the frequency-domain analytical results match the measured data well over all the measured significant wave heights, which ranged from 6.5-ft to 26-ft. Since the riser and LMRP RMS motions are well predicted by models, it follows that wellhead loads are well estimated from analytical models. The frequency-domain analytical results were further verified for a few cases by time-domain analyses. Both measured and analytical spectra generally exhibit peaks at similar frequencies. While the first analytical riser mode is clearly identified in the measured data, the analytical blow out preventer (BOP) stack/riser mode is not as evident in the measured data. Further, the measured peak close to the analytical stack/riser frequency is very broad. These observations and additional sensitivity studies showed that further investigation for sources of damping due to soil and/or stack hydrodynamics is required.
This work shows that the modeling techniques used presently for analyzing the global riser/stack response in frequency- domain are reasonably accurate for the analyzed conditions.
Case Studies of Industrial Standardizing and Cost Efficient Offshore Concept
Authors: Wang Aimin , DaSilva Otto , Tredennick Owen 
Published: April 2017

Abstract
Low cost and high efficiency is a necessity for the offshore industry in response to the current low oil price. This paper presents case studies investigating the key factors of standardization and cost efficiency from the EPCI perspective for deep water offshore projects based on two semisubmersible floating production systems (FPS) recently installed and currently operating in the GOM. The philosophies used and methodologies applied in the engineering design, construction, and installation of both units will be reviewed through different stages of the projects.
The paper presents how safety, standardization, operability and constructability were considered and prioritized in the projects from the concept through detail design resulting in cost and schedule efficiencies. Some special considerations and methods utilized during different design stages which facilitate ease of construction and installation are discussed.
Pipe-Clamping Mattress to Stop Flowline Walking
Authors: Frankenmolen Sebastiaan , Ang Sze-Yu , Peek Ralf , Carr Malcolm , MacRae Ian , White David , Rimmer Jeffrey 
Published: April 2017

Abstract
Thermal gradients from a heating front travelling down a flowline at start-up can cause a flowline to walk much like a worm creeps by repeated contractions and expansions of its body. To stop this for the Malampaya flowline, pipe-clamping mattresses (PCMs) were invented, developed, and deployed within a period of 12 months. The objective of this paper is to share the knowledge and experience from this novel but effective solution to mitigate pipeline walking.
PCMs provide a cost-effective alternative to rockdump or conventional mattresses to axially restrain a pipeline at a location chosen so that the required restraint capacity is minimized. They are inspired by conventional mattresses and bear some similarity to them, but they are designed so that the weight of the mattress acts to clamp the pipeline with a high leverage. Thus 100% of the weight of the mattress is effective in generating axial friction with the seabed. This solution can be applied at any point along the line (chosen to minimize the required resistance) without requiring flanges or collars on the pipeline.
From the most recent survey results 15 PCMs with a dry weight of around 9 tons per PCM, plus 7 tons for the logmat installed over every PCM appear to be effective to stop the walking of the Malampaya flowline. This performance is as expected from extensive analysis (FE and otherwise) to reproduce the observed walking behavior prior to restraining, to estimate the required restraint capacity, and to estimate the resistance provided by the PCMs.
This paper describes the PCM, the clamping forces they generate by leveraging the weight of the PCM and logmats installed over them, and how the friction generated with the soil is estimated from interface shear tests on samples collected from the site, considering cyclic pore pressure generation and dissipation effects. It also briefly covers FE analyses to reproduce the observed walking behavior, and determine the required restraint capacity, the PCM fabrication, installation, and monitoring of the post-installation performance.
New Generation of Ultrasonic Technology for Cement Evaluation in Complex Environments
Authors: Shaposhnikov Pavel , Thierry Sylvain , Lake Patrick 
Published: April 2017

Abstract
Now, more than ever, the integrity of the wellbore before the recommencement of drilling operations or production of reservoir fluids, is fundamental to safe operations. Stricter well control policies have been instated in recent years, so it is critical to perform casing inspection, and cement evaluation measurement surveys to ensure adherence to regulatory codes.
As exploration and development drilling activity breach new horizons, it brings new challenges to cementing operations and subsequent cement evaluation surveys. Heavy drilling muds, extra-large casing sizes, and narrow drilling windows: cement to mud weight ratios which can led to cement contamination are just a few. Until recently these constraints limited the usefulness and reliability of ultrasonic measurements under the said conditions.
This paper describes a new generation of ultrasonic sensors and technology that fills the gaps left by predecessor technologies and allows operators to feel confident and at ease with the integrity of their wellbores, even under the most taxing conditions. The advantages and associated cost savings enabled through the utilization of this technology are illustrated in the case studies at the end of the paper.
Water Column Velocity Function for the Gulf of Mexico
Authors: Pryne Daniel , Kucera Michael , Gharib Jamshid 
Published: April 2017

Abstract
Water column velocities derived from deep water Gulf of Mexico conductivity, temperature, and depth data has been modeled into a seventh-order polynomial to provide a function for seismic time to depth conversions. This model is most accurate in Gulf of Mexico water depths ranging from about 1,500 to 13,000 ft, away from anomalous areas of higher temperatures and salinity. The utility of this equation extends from geohazard assessments to augmenting incomplete velocity profiles for geophysical surveys.
Integrated Study of a Complex Seabed For the Stones FPSO
Authors: Hadley C. , Bradford K. , Young A. , Trandafir A. C. , Bruce B. 
Published: April 2017

Abstract
Shell's Stones field is located below the Sigsbee escarpment on the continental rise in the Walker Ridge area of the Gulf of Mexico, in a water depth of approximately 9,500-ft. The seafloor is irregular due to the presence of furrows, which have been eroded by bottom currents. These features, combined with positioning uncertainties associated with surveys in this extreme water depth, posed a unique challenge to characterization of the seabed and to siting of infrastructure.
Design soil properties were selected by integrating Autonomous Underwater Vehicle survey data with data from two geotechnical investigations. These data sets are typically correlated by using the seafloor as the vertical reference datum. This was not possible in the Stones field, so the data was instead correlated to a marker horizon, which was common to both the shallow seismic and the geotechnical data sets. Additionally, seafloor bathymetry data were screened using pre-determined criteria to optimize FPSO mooring anchor locations.
This paper presents sample geophysical and geotechnical data from the Stones field and describes the process used to integrate the data and develop design information. The selection of FPSO mooring anchor locations within the variable bathymetry is also described. Finally, installation records from the FPSO mooring system are presented, which demonstrate the value of the integrated approach to site characterization. The process for data integration at Stones can serve as a model for future developments, with complex seafloors.
Driver Selection for Refrigerant Compressor for Small Scale FLNG
Authors: Kumar Balesh , Jang Jungmoon 
Published: April 2017

Abstract
Recently the demand of LNG has increased and will continue to increase in near future. To meet this demand exploration has gone into offshore with the Development of FLNG, with one of them having completed his first off take to an LNGC and several of them under Construction at the time this Technical paper is prepared.
One of the challenges lies in the correct selection of the driver for LNG refrigeration compressor on FLNG. Although both mechanical drive as well as electrical drive is applied on land based LNG plant, the situation is quite different in offshore as very limited experience is available and no electrical drive has been selected so far for FLNG facility.
The findings on drive selection and their economic and operational advantages are discussed in this paper.
Power generation system and refrigerant compressor system are very important systems to be evaluated together for the FLNG facility to achieve optimum solution.
FLNG has limited space, sensitive to motion, standalone power generation, inherent difficulty for providing maintenance support and limited operating staff. These factors are well known to FPSO/ FLNG providers and all of them will agree that driver should be simple, robust, reliable and cost effective.
We have three types of choices available for such large compressor i.e. steam turbine, gas turbine (GT) and Electric Motor (EM). Comparison focuses on the GT and EM along with their characteristics
FLNG facility does require standalone electric power generation on board. The electric power generation can be achieved either by GT generator set, steam turbine generator sets or gas engine sets. The power generation has impact on driver selection in terms of improving thermal efficiency, availability, inventory control and use of fuel.
There are several parameters which need to be considered for evaluation before finalizing the driver selection for Refrigeration compressor on FLNG. A case study previously developed under OTC-27731 (Associated Gas FLNG with One or Two Liquefaction Trains) is used to map these parameters to depict the reality of driver on small to mid-scale FLNG facility
Therefore, this paper will evaluate how to select correct driver system for refrigeration compressor considering all the factors. It will also provide useful guidelines for owners, field operators, designers and EPC contractors to arrive at right solution for their specific application.
Hydrate Formation and Transportability Investigations in a High-Pressure Flowloop During Transient Shut-in / Restart Operations
Authors: Srivastava Vishal , Majid Ahmad A. A. , Warrier Pramod , Grasso Giovanny , Chaudhari Piyush , Dendy Sloan E. , Koh Carolyn A. , Wu David T. , Zerpa Luis E. 
Published: April 2017

The presence of gas hydrates in subsea production is identified as a major flow assurance challenge due to the rapid formation of hydrates and their risk of causing flowline blockages. The risk of hydrate-associated blockages could be higher for transient (shut-in/restart) operations compared to continuous production. Often in offshore production, there are unplanned shut-ins that could lead to increased operational hazards. Despite the practical importance, few studies have addressed the hydrate plugging mechanisms during transient operation.
To investigate hydrate transportability in transient operation, tests were performed using an industrial-scale flowloop (3.8 inch in internal diameter and 295 feet in length) with crude oil for a range of water fractions (30–90 vol.%), at 5 wt.% salinity, and across a range of mixture velocities (2.4 -9.4 ft/s). For the tests performed at 50 vol.% water cut (WC) at 5.7 ft/s, the pressure drop and mass flow rate measurements suggest that the transient (or restart, RS) test could result in an earlier onset of hydrate bedding, occurring approximately twice as fast, and may lead to a higher relative pressure drop when compared to the continuous pumping (CP) test. These flowloop experiments suggest that for the RS tests, rapid hydrate formation and agglomeration followed by the water-in-oil (W/O) emulsion destabilization could cause an early increase in pressure drop (and higher operational risks) compared with the CP tests. The tests using an anti-agglomerant (AA) additive (at 1 and 2 vol.%) were performed at 50 vol.% water fraction for all mixture velocities. The tests with an AA indicate that 2 vol. % AA (at all velocities) could prevent hydrate plugging and maintain a slurry flow at 50 vol. % WC for both RS and CP tests. The tests with 1 vol.% AA (at 5.7 ft/s for 50 vol.% WC) show larger fluctuations in pressure drop in the RS test compared to CP tests performed under similar conditions. It is suggested that an improved understanding of hydrate plugging mechanisms during transient operations could help in the development of advanced strategies to manage hydrate transportation in typical subsea operations, particularly involving unplanned shut-ins and subsequent restarts.
Workflow to Evaluate Wax Deposition Risk Along Subsea Production Systems
Authors: Coronado O. , Kak A. 
Published: April 2017

Abstract
The potential for wax formation and deposition along subsea production systems pose a severe flow assurance risk. During early stages of a field development (when information is limited), the risk needs to be quantified in order to develop preliminary mitigation strategies. This paper presents a workflow that can be used to evaluate the wax deposition risk for any field development by integrating the available wax laboratory data with simulation tools.
The proposed workflow consists of tuning fluids models, benchmarking the wax deposition models (using the measured wax deposition rates), and conducting wax deposition simulations with the benchmarked models. Deposition mechanisms such as diffusion and shear stripping can be adjusted during the benchmarking step.
The wax deposition predictions can be used to evaluate various design options during development stage and for devising operating strategies throughout the life of the field (such as insulation requirements, injection of paraffin inhibitor, pigging operations, etc.). In field developments where thermal management is a challenge and wax deposition cannot be avoided, a structured approach toward wax modeling is crucial to make the right engineering decisions.
Wax laboratory measurements alone are not sufficient to quantify the wax deposition risk because of the uncertainties associated with the laboratory results and the difficulties to reproduce the actual field production conditions. When comparing the results obtained with the default wax model coefficients (no benchmarking) and the benchmarked models, the predictions are significantly different. Similar deviations are observed with the predictions based on wax data reported by different laboratories (for the same fluid sample). The overall design and operating strategy are highly dependent on wax deposition rates. Therefore, the discrepancies between the wax data measured by different laboratories suggest the need to standardize the test protocols.
The main objective of the proposed workflow is to try to bridge the gap between the laboratory wax test measurements and transient flow assurance modeling. The ultimate goal is to reflect the wax characteristics in the large scale field operations. This workflow is intended to facilitate the communications between engineering design teams and flow assurance laboratories; because more representative data are needed to better predict the wax problem throughout the field life.
Integrating Decision Support Models with Market and Non-Market Value Attributes for Platform Decommissioning: An Effective Approach for Resolving the Challenges Inherent at the Nexus of Science and Policy
Authors: McCann B. M. , Henrion M. , Bernstein B. , Haddad R. I. 
Published: April 2017

Abstract
Many critical factors must be considered in determining the most feasible and appropriate options for decommissioning offshore oil and gas platforms, including alternatives from complete removal to partial removal with artificial reefing. Using financial-based cost/benefit analysis to evaluate decommissioning options neglects the complexities inherent in a successful platform decommissioning process, which includes non-monetary values such as the production of greenhouse gasses and the gains and/or losses of ecological services due to partial or complete removal.
Multi-attribute decision analysis provides technically defensible consideration of both market and non-market values associated with the outcomes of rig decommissioning while allowing stakeholders to clearly and transparently investigate and evaluate the nexus between financial considerations and other factors (e.g., air/water quality, biological productivity, ocean access) that drive public policy. In California, the PLATFORM decision support model was a key component in helping a diverse group of stakeholders reach consensus on the preferred policy of partial removal and artificial reefing, which ultimately resulted in the creation of a public regulatory framework for rig decommissioning—the California Marine Resources Legacy Act.
We describe how to use multi-variable decision analysis to facilitate offshore oil and gas platform decommissioning. We implemented decision analysis as a software tool (PLATFORM) to clarify and evaluate decommissioning alternatives against a comprehensive set of objectives, including both market and non-market values. Decommissioning options selected for in-depth analysis were complete platform removal and partial removal to 85 feet below the water line, with the remaining structure converted to an artificial reef. PLATFORM performed key analyses of the impacts of each option (e.g., on costs, fishery production, air emissions). The analysis found a near-consensus of stakeholders in support of partial removal and a "rigs-to-reefs" program. Decision support models, such as PLATFORM, are readily adaptable to support regulatory decision-making and alternatives analysis for decommissioning worldwide, including the North Sea, Australia, and Asia.