bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hydraulic Fracture Design for the Lower Tertiary Gulf of Mexico: Optimization Under Uncertainty
Authors: Podhoretz S. B. , Valkó P. P. 
Published: June 2014

Abstract
In this work we developed a methodology for making the strategic decisions regarding number and dimensions of hydraulic fractures for a high-cost, high-risk offshore vertical well in formations such as the Lower Tertiary Gulf of Mexico. Uncertainty is associated with the characteristics of the reservoir, the economics of the fracturing cost, and the fracture height growth. Reservoir uncertainty is manifested in the vertical permeability. Economic uncertainty exists in the total cost of the fracture treatment, which depends on the number of stages. Design uncertainty includes fracture height growth prescribed by a given aspect ratio. The method developed here is applicable to vertical wells with multiple, partially penetrating fractures in an anisotropic formation. The method applies the utility framework to account for financial risk. The optimization problem is represented as a two stage stochastic program with simple recourse.
Permanent Magnet Motor-Driven Pump Systems for Subsea Boosting in the Arctic Fields
Authors: Ganatra N.K. , Strikovski A. , Hollingsæter T. 
Published: June 2014

Abstract
In 2012, a unique combination of multiphase pump hydraulics and a 3.2 MW, 6, 000 rpm permanent magnet motor was qualified for subsea boosting applications. This new pump system delivers a versatile toolbox that can be deployed to fields in the Arctic and throughout the world. The qualification unit uses field-proven helico-axial hydraulics that are capable of boosting production fluids with gas volume fractions (GVF) as high as 100%. Further, the pump has been designed with modular construction, which allows the use of different types of hydraulics, viz. helico-axial, hybrid or single-phase, with the same qualified motor and auxiliary sub-systems.
The permanent magnet synchronous motor, integral to the qualified pump design, offers significant benefits over conventional induction motors. Combining the stiff, fully-contained rotor and the large rotor-stator "air" gap allows operating speeds up to 6, 000 rpm for the liquid-filled permanent magnet motor. In high GVF scenarios, the high speed operation allows differential pressures that are much higher than those generated with induction motors operating at 4, 000 rpm. The permanent magnet motor has the unique ability to provide the full load torque from zero speed, thus making it suitable to overcome some of the cold pump startup challenges of the Arctic. Sealed cable-wound stator and the rotor encasement in a carbon fiber sleeve permit the use of water-based barrier fluid, which is appropriate for the Arctic fields, where heightened environmental consciousness has added to the existing production challenges.
The barrier fluid pressurization system incorporates pressure control valves that operate purely on mechanical principles. This results in a stiff, fast-acting and reliable barrier fluid pressurization system that closely follows the pressure transients of the production fluid even in the long step-out distances of the Arctic. The successful qualification work includes permanent magnet motor startup and operation with long tiebacks, inclusive of step-up and step-down transformers, thus providing a system that is crucial to sub-ice power transmission.
Ongoing development of a new 6 MW, 6,000 rpm, 1, 034 bar (15, 000 psi) rated pump will better address some of the Arctic challenges by allowing the use of smaller pipe sizes, requiring the installation of one pump in place of two, simplifying subsea electrical power distribution and utilizing fewer mechanical interfaces. The 6 MW pump will provide high throughput capacity in high GVF applications combined with high pressure rise, thus resulting in longer tie-back and deeper water capabilities.
Wellhead Pressure Interlock Protection
Authors: Carlson Russell , Wright LaQuayne 
Published: June 2014

There are many pressure related issues of concern in petroleum well production. Both high and low pressure conditions are indications of problems that must be addressed to maintain well safety and performance. A flexible and reliable control system for pressure monitoring provides a failsafe interlock which prevents well operation under a variety of unsafe conditions.
Proper operation of a well requires the system be maintained within a specific pressure range. The range can vary from well to well, with offshore pressures typically higher than onshore. The concept remains the same – if pressure is too high, there is a risk of catastrophic failure. If pressure is too low, it may indicate clogging or catastrophic failure at the site.
Well control systems have evolved and become more sophisticated as technology and understanding have improved. Instrumentation is keeping pace and can now provide high integrity monitoring and protection with high efficiency features that increase system safety and reduce maintenance time and effort.
Developments in Marine Gas Hydrate Exploration
Authors: Boswell Ray 
Published: June 2014

Abstract
The evaluation of gas hydrate resource potential continues to spread across the globe. Over the past decade, exploration emphasis has steadily shifted away from the confirmation of the presence of gas hydrate to the more complex issue of prospecting for specific accumulations of highly-concentrated gas. In general, concepts for gas hydrate exploration have evolved from a search for bottom-simulating reflectors to a process much more akin with conventional oil and gas exploration that features the direct detection of gas hydrate accumulations in seismic data supported by integrated geological/geophysical/geochemical studies that address issues of gas supply and reservoir distribution. This report aims to assimilate the lessons learned to date to outline a general exploration procedure for gas hydrate resources and outline remaining research challenges as follows:delineation of the gas hydrate stability zone;the identification and evaluation of strong amplitudes of the same polarity as the sea-floor ("peak" amplitudes) within that interval, as well as intervals of increased acoustic velocity;mitigation of the geologic risk inherent in such prospects via seismic mapping of amplitude distribution along prospective horizons as well as broader seismic facies analyses; andfurther risk mitigation through assessment of evidence of gas presence and gas migration into the gas hydrate stability zone.
Integration into the Sandface Tool System for Gravel and Frack-Pack Installations with a Fiber Optics Wet-Mate Connector System
Authors: Drakeley B.K. , Morrison F. , Grigsby T. , Martinez S. , Perez E. 
Published: June 2014

Abstract
Operators have always sought the capability to monitor pressure, temperature, and flow across the sandface in gravel and frack-pack (and stand-alone screen) completions in real time in order to optimize production, and gain advanced notice of remedial needs.
In most sandface completions, the lower completion contains the screens, and the completion is performed in two stages: the service tool string is run first to perform pack operations, and the second stage "mates" the upper completion string to the lower completion.
The unique capabilities of fiber optics sensing techniques such as Distributed Temperature Sensing, Point Pressure and Temperature, Array Temperature Sensing, and Distributed Acoustic Sensing can provide the desired production and reservoir information across the sandface. However, accomplishing this requires a fiber optics wet-mate connector system to link the fibers in the lower and upper completions.
Weatherford had run a fiber optics wet-mate connector system in Oman in April 2005, and a key driver for the new connector system was to use a lower profile connector to maximize the production flow area with Halliburton's gravel and frack-pack completion technology.
The design essentials for the 9 5/8-in. × 4 ½-in. to 5-in. system, and required field operations for successful deployment are described in the paper along with the development and qualification process performed in laboratory, and test well conditions completed in May 2013. These were to ensure that the two key challenges of alignment and debris management had been successfully resolved. The final System Integration Test (SIT) for qualification was run at approximately 3,000 ft, and witnessed by a major operator. Subsequently, a demonstration SIT in the same well was witnessed by multiple operators in November 2013. The mechanical and optical measurements taken during the qualification process will be presented to demonstrate that the desired production/reservoir information can be provided.
Optimizing Response Strategies to Improve Subsea Equipment Availability
Authors: Pearse J.A. , Botto A. 
Published: June 2014

Abstract
Operators must develop a holistic response strategy to equipment failures that will ensure that effective control is established as quickly as possible in order to safeguard life, protect the environment, ensure containment and control the emergency to minimize damage to assets. This paper will focus on the financial impacts of subsea equipment failure and how real time data improves subsea equipment availability. Failure of equipment must be detected prior to occurrence in order to reduce downtime and increase production availability, i.e. minimize the commercial consequences.
A methodology will be presented where equipment failure will be assessed based on its operational risk, i.e. probability of failure assessment versus cost of failure analysis. In order to assess the probability of failure, numerous failure data gathering methods should be assessed such as:Condition monitoring? Real time data trending? Operations reports and production trackingFailure management? Integrity management plans (risk-based assessment)? Inspection data? Central maintenance management system? Historical failure data e.g. OffShore Reliability Data (OREDA) or WellMaster / SubseaMaster? Failure Modes Effects and Criticality Analysis (FMECA)? Root Cause Failure Analysis (RCFA)
An efficient comparison and gap analysis of these data sources should be completed recognizing data patterns and identifying trends, so that the risk for equipment failure and production loss can be estimated. In addition, evaluation of the equipment failure's commercial impact based on equipment lead time and spares availability ensures that all probable failures have a response plan in place. A well-planned response plan can reduce the repair time delay significantly and therefore limit the impact on production efficiency.
A case study will be presented; management of risk will be used as a basis for quantifying the risk ranking for different subsea equipment. A response strategy analysis will evaluate the cost benefits of the level of preparedness required for each subsea failure. The case study will demonstrate the value of real-time data monitoring and how data analysis improves production efficiency and possibly influences all future subsea equipment design. In addition, in order to reach a successful repair response strategy, it is imperative that the appropriate information, techniques, materials, spares, and personnel are available to enable an expedited response.
Innovative Positioning of Downhole Pressure Gauges Close to Perforations in HPHT Slim Well During a Drillstem Test
Authors: Al-Nahdi AbdulHakim , Gill Harmohan S. , Kumar Vikash , Sid Imad , Karunakaran Prasad , Azem Wasim 
Published: June 2014

Abstract
An operator successfully tested an offshore, exploration well in a high-pressure and a high-temperature (HPHT) reservoir, where the pressure exceeds 10, 000 psi and the temperature is approximately 400°F. The tested intervals are behind a 4.5-inch liner. Slimhole drillstem test (DST) tools have been considered but not selected due to the restricted internal diameter and limited intervention capability. Instead, a cased hole DST method has been selected in which DST tools are set in a 7-inch liner, and tubing-conveyed perforating (TCP) guns are run in the 4.5-inch liner on the bottom of a long tailpipe.
The first DST has been successfully completed, with the pressure gauges located at the gauge carriers in the 7-inch liner, several thousand feet above the test interval. Pressure and temperature data from downhole gauges have been analyzed and found to exhibit significant wellbore-phase redistribution effects because of gauge location. This has resulted in significant uncertainty in reservoir characterization. Solutions considering the HPHT and slimhole design have been investigated.
We present a unique method of placing the downhole gauges on top of the perforating gun during an HPHT well test operations where formation temperature exceeded 400°F. Five DSTs have been performed using this technique with successful recording of downhole pressure and temperature data, despite the perforating gun shock and hostile environment encountered.
A comparison of pressure transient interpretations as well as a comparison of data gathered by the gauges located above the guns (immediately above the perforations) with the data from gauges in the 7-inch liner will be presented to show the potential for incorrect interpretation due to the gauge placement. We will also discuss the unseen behavior of flowing gas temperature at perforation depth based on actual temperature data recorded.
Investigating Modern Ultra Deepwater Sedimentary Processes in the Central Gulf of Mexico Using High Resolution Geophysical Data
Authors: Prieto Maria I. , Moscardelli Lorena , Wood Lesli 
Published: June 2014

Abstract
A detailed geomorphologic and shallow stratigraphic interpretation was performed in three different geomorphological domains of the ultra-deepwater region of the central Gulf of Mexico (GOM) using a set of high resolution bathymetry and subbottom profiles that were acquired at four major oil fields in the Green Canyon and Mississippi Canyon protraction areas. The seafloor expression of the study areas allowed defining three different geomorphological provinces: Minibasin, Sigsbee Escarpment and Disconnected Canopy Province. The geomorphological expression of these provinces is primarily the result of the dynamic behavior of the underlying salt, in which these regions experienced different degrees and types of substrate deformation. Structural deformation affecting these areas has been very dynamic through time enhancing the occurrence of both regional and localized gravity-induced deposits. Regions of high relief along diapiric slopes (e.g.: Sigsbee Escarpment) are affected by headwall failures and the near seafloor stratigraphy reveals the complex dynamic of eroded and re-deposited sediments that have been affected by both gravity- and current-driven processes. This study seeks to improve our understanding of how local bathymetric variabilities (linked to underlying structural controls) interact with gravity-driven and current-controlled processes in the ultra-deepwater region of the GOM to generate the near seafloor stratigraphic record that is observable in our study areas.
Solubility Study of Magnetite under Extreme High Pressure and High Temperature
Authors: Yan C. , Guraieb P. , Huang J. , Contreras E. , Tomson R. C. , Tomson M.B. 
Published: June 2014

Abstract
With the continued development of offshore production in deepwater wells, a greater understanding of scale formation and corrosion under extreme high pressure and temperature (xHPHT) is needed. In order to better predict scale formation and scale solubility, knowledge of the thermodynamic and kinetic properties of these mineral systems under xHPHT conditions is important. Research to expand the amount of data and models for different types of scales at these conditions will reduce offshore production risk and improve human safety in ultra-deepwater (UDW) production.
A novel flow-through apparatus has been developed to perform a scale solubility, dissolution, and precipitation study of minerals under high pressure (up to 24, 000 psig), high temperature (up to 250 °C), and high total dissolved solids (TDS, up to 360, 000 mg/L). This part of research will focus on the solubility study of magnetite and siderite. Studying dissolution and precipitation will improve understanding of the formation of passive layers (Fe3O4 and FeCO3) and their phase transitions as temperature increases, as has been observed in corrosion research. In this work, effects of reaction conditions, including temperature, pressure, pH, and brine composition on solubility of magnetite, have been investigated. Reduction potential is an important parameter which will affect magnetite solubility dramatically and is sensitive to brine composition. Details of the experimental setup and preliminary results of this research will be presented.
A Model Test Ice Resistant Study of FPSO And Yoke Mooring System In Ice Influenced Areas of Bohai Bay
Authors: Li Jianmin , Li Tongkui 
Published: June 2014

AbstractThe ice resistant capacity of a FPSO and its yoke mooring system is one of the critical problems for oil field developments in the ice influenced areas of northern Bohai Bay. A model test study was conducted in the 40m×40m×2.8m Ice Tank of Helsinki University of Technology in Espoo, Finland for evaluating the maximum ice loads acting on the Suizhong 36-1 FPSO and Yoke Mooring System.The FPSO hull, yoke mooring system, and floating ice packs were simulated for the full-scale processes in miniature. The FPSO hull and the yoke mooring jacket structure are reduced linearly in dimensions and cubic in mass, displacement, and volume, to ensure the geometric similarity. Many factors and properties are of interest when simulating ice in the ice tank. A scale ratio of 1:30 was adopted in the model test. Therefore the ice used must also be 1/30th the thickness and 1/30th the strength. ice pieces flowing, as well as jamming around the FPSO hull and the yoke mooring jacket, are modeled in the ice tank. It is very challenging to correctly reduce the ice properties of interest, thus providing an accurate simulation. The actual environment simulated in a combination of wind, current and ices is of prime concern.This paper presents the methodology and results of the six model tests which are conducted to simulate various combinations of floating pack ice thicknesses, ice bending strengths, ice flowing speeds, FPSO headings and rotations, etc. The findings include the ice loads acting on the FPSO and Yoke Mooring Jacket at two ice flowing speeds of 0.5m/sec and 1.0 m/sec and three FPSO headings of 0, 90, 180 degrees, respectively. The FPSO model are pulled or pushed through the loose broken ice sheet to simulate the interaction between the ices and the FPSO hull. The ice load and mooring load on the yoke arms were measured by force transducers. The rotation angle of the yoke arms around the mooring jacket were also measured by angular transducers.
The Devil Is In The Details - Lessons Learned From Design Failures in Underwater Monitoring Systems
Authors: Strout J.M. , Sparrevik P.M. 
Published: June 2014

Abstract
Success is of course the most desirable result of any project, but the value of failures in terms of advancing technology should not be underestimated. This paper draws on the experiences of over thirty years of designing and delivering operational monitoring systems for the oil and gas industry, condensed to a short presentation of valuable lessons learned from less-than- successful designs and deployments.
The article covers several principle themes, presenting the failures experienced, evaluation of the root cause of the failure, and subsequently the measures implemented to mitigate similar failures in the future. The insights and solutions presented will be beneficial for organizations planning or executing the design and installation of an underwater monitoring network.
The first theme presented is failure due to corrosion. Corrosion is an insidious process, which if not properly managed in the system design will ultimately result in failure. The obvious culprit is the use of common steel, whereas less obvious culprits include combinations of metal types (including titanium), inadvertent use of alloys, surface treatments and coatings, as well contact with sediments, cements and grouts.
The second theme is barrier philosophy - leaky enclosures, hygroscopic materials, and capillary forces can all contribute to failures. A leaking barrier does not necessarily mean a catastrophic failure, and with the implementation of a few good design details, even a leaky system may be able to operate for long periods before eventually failing.
The third theme examines lessons learned related to deployment and operation of equipment in various environments: in conjunction with permanent infrastructure, as autonomous installations on the seabed, or as moored or drifting floating structures. Each of these operating environments poses challenges, including harsh natural environmental conditions, accessibility, interaction by third parties, and various rules, regulations and company specific practices.
Sound engineering combined with practical experience is the best starting point for a successful design. This article summarizes some of our 'trial and error' experience related to the practical and operational challenges inherent in an underwater monitoring system design and deployment, and these experiences will be useful for others when commissioning, designing and deploying similar systems.
Implementation of Dual Gradient Drilling
Authors: Stave Roger 
Published: June 2014

Abstract
RMR - Riserless Mud Recovery technology is a "first out" commercial Dual Gradient Drilling (DGD) technology. The technology has to date been deployed on more than 200 wells. The majority of wells are in less than 2000ft water depth, and the maximum water depth to date is close to 5000ft.
Initially the development was driven by a zero-discharge demand, but early on the benefits related to Dual Gradient Drilling became the main drivers for the Operators to select the technology. In fact, for only a few of the 200 wells to date, zero-discharge has been the driver. The technology allows weighted and engineered drilling fluid to be used on the top-hole sections and volume control is enabled through circulation of fluid to surface - same as post-Blow Out Preventer (BOP). Borehole quality is significantly improved and planned Total Depth (TD) can be reached without the risk of running out of fluid.
The Managed Pressure Cementing (MPC) technology has been developed as an add-on to RMR. This technology has been used for more than 20 wells to date. Combined with the improved hole quality RMR can deliver, MPC improves the chances of circulating the cements slurry around the well without losses. The pressure is managed and controlled during the circulation time, and monitored during the setting time.
A third development of the core RMR technology has been EC-Drill. EC-Drill has been deployed on 6 jack-up wells and 3 deep water wells drilled from a Semisubmersible rig (SEMI). North Sea and Gulf of Mexico (GOM) deployments are under ways. EC-Drill enables precise control of Bottom-hole Pressure(BHP) through manipulation of the fluid column within the Drilling Riser. Pressure build up due to circulating friction is eliminated and flow rate / Rate of Penetration (ROP) can be increased. By managing Equivalent Circulating Density (ECD), drilling through tight drilling window is enabled. Depleted / low pressure reservoirs can be drilled with conventional / low mud weights. EC-Drill in its present form delivers primarily ECD control and only partial - not full DGD capability.