bluuebunny/crossref_metadata_2025_split huggingface dataset:
An Environmentally Friendly Method to Evaluate Gravel and Frac Packed Intervals Using a New Non-Radioactive Tracer Technology
Authors: Han Xiaogang , Duenckel Robert , Smith Harry , Smith Harry D. 
Published: June 2014

Abstract
Recently a new non-radioactive tracer (NRT) technology has become available to locate proppant in induced fractures that offers a viable alternative to the prior technology which utilizes radioactive (R/A) tracers, thereby eliminating the environmental, safety, and regulatory concerns associated with the R/A materials. This new non-radioactive tracer technique also has application in evaluating gravel packs and frac packs. The new technology employs a non-radioactive ceramic proppant containing a high thermal neutron capture compound (HTNCC). This compound is inseparably incorporated into each ceramic proppant grain during manufacturing in sufficiently low concentration that it does not affect any proppant properties. This tagged proppant can also be used as, or mixed with, conventional gravel or frac packing materials prior to downhole placement. The NRT taggant is detected using standard pulsed neutron capture (PNC) logging tools, with detection based on the high thermal neutron absorptive properties and/or capture gamma ray spectral properties of the tagged pack material relative to other downhole constituents. The tagged pack material is indicated from:decreases in after-pack PNC detector count rates relative to corresponding before-pack count rates,increases in PNC formation and borehole component capture cross-sections (Sfm and Sbh), and/orincreases in the computed elemental yield of the neutron-absorbing tag material, derived from the observed PNC capture gamma ray energy spectra.
In many frac-packing situations, combining Sfm and Sbh data permits identification of fracture height behind casing. In some applications, enhancements to these methods have also been developed to eliminate the requirement for the before-pack log. In this paper, log examples illustrate the effective detection of HTNCC tagged proppant placement in fractures and cement, and Monte Carlo modeling illustrates the viability of the detection/evaluation of gravel packs and frac packs using HTNCC tagged pack material. The modeling data and logs indicate the applicability of this effective, safe, and environmentally friendly logging technique to locate the placement of non-radioactively tagged downhole pack material in both gravel pack and frac pack evaluation.
Numerical Study on Eastern Nankai Trough gas Hydrate Production Test
Authors: Zhou Mingliang , Soga Kenichi , Xu Ermao , Uchida Shun , Yamamoto Koji 
Published: June 2014

Abstract
The fully coupled methane hydrate model developed in Cambridge was adopted in this numerical study on gas production trial at the Eastern Nankai Trough, Japan 2013. Based on the provided experimental data of hydrate soil core samples, the soil parameters at Eastern Nankai Trough were successfully calibrated. With calibrated soil parameters and site geometry, a 50 days gas production trail was numerically simulated using the fully coupled simulator CMHGS (Cambridge Methane Hydrate Geomechanics Simulator). The geomechanical behavior of hydrate bearing sediments and production history results under 3 different depressurization strategies were explored and discussed. With the latest gas production site data, several input parameters for the numerical study were calibrated and an updated numerical simulation of the gas production test was carried out. The comparison of gas production history and vertical displacement along the wellbore between the updated simulation and the previous simulation results suggest large discrepancy, which highlights the importance of parametric study for numerical simulation of the gas hydrate production test. Therefore, parameter sensitivity of production history and vertical displacement were investigated and concluded the relative permeability curve; temperature profile, sea water salinity and permeability anisotropy all influence production results and mechanical responses.
The Application of Noise Attenuation Method Based on Frequency and Amplitude in China's Bohai Bay
Authors: Dong Shuili , Fan Baocang , Wang Zheng , Qu Chaoyin 
Published: June 2014

Abstract
Noise attenuation is one of the most important steps in seismic data processing and it directly affects the final imaging quality of seismic data. Traditional de-noising methods can easily eliminate simple noise, such as spike noise or linear noise, but they can't efficiently handle non-linear external noise. That problem can be solved by using technique based on frequency and amplitude. The method detects and attenuates external noise making the most of differences between external noise and primary in sub-bands, and it can protect the primary by establishing threshold factors varying with frequency and time. This method has been successfully applied in the external noise elimination processing of the seismic data in China's Bohai Bay. Processing results showed that the method can remove external noise satisfactorily while the primary is preserved as much as possible. Other tests indicated that this method was also effective for attenuating near-offset multiples.
Planning and Feedback for Deepwater Drilling Riser Operation in High Currents, Typhoons and Cold Front
Authors: Saruhashi T. , Sawada I. , Kyo M. , Miyazaki E. , Yamazaki Y. , Yokoyama T. , Bhalla K. , Stahl M.J. , Ganpatye A. , Han Y. , Gong L. 
Published: June 2014

The dynamically positioned drillship, Chikyu, has performed riser drilling operations twice in high-current environments in the Nankai Trough, offshore Japan. The drilling site is located in a water depth of approximately 6, 361 ft (1, 939 m) and regularly experiences the Kuroshio Current. The mean surface current at the site is 3.5 knots, and the 1-year extreme current is 7.0 knots. In addition, the current is not seasonal and typically changes frequently during the day. The Nankai Trough site also experiences intense typhoons during the months of July to October and frequent cold fronts from November to January. Thus, all operational phases need to be analyzed thoroughly to account for these harsh environmental conditions.
The following operational issues need to be carefully considered: riser deployment and retrieval, BOP/LMRP landing approach with vessel drifting, determination of watch circles, typhoon evacuation plans, hang-off operational criteria, evacuation plans for cold fronts, allowable riser tension range, and riser fatigue measurement with vortex-induced vibration (VIV) monitoring.
Assessment of deepwater/high-current riser drilling systems provides a means for identifying critical stages of drilling operations and enables their successful execution. Feedback from two drilling campaigns (2012/2013) conducted in high currents are described in this paper. The actual riser response matched riser analysis results to a significant degree. Extreme operations including typhoon evacuation, drilling operations in up to 5.2 knot currents, BOP landing in 4 knots, and emergency disconnect sequences (EDS) due to a cold front were performed in 2012. VIV fatigue damage was extremely low, with a maximum of 1.5% fatigue damage in the entire riser assembly in 2012. In 2013, operational criteria for cold front events were reviewed again since the number of these weather events experienced in 2012 was 3 to 4 times greater than in a typical year.
General guidelines and associated criteria are provided to evaluate a drilling riser system under high currents and approaching typhoons. This paper focuses and discusses the major operational concerns in these harsh environments. In addition, a riser fatigue monitoring system is described that has been used to track fatigue damage on riser joints both from VIV fatigue and wave loads.
Experimental Study On Compression Indices Of Gas Hydrate-bearing Sediments
Authors: Kim H.S. , Cho G.C. 
Published: June 2014

AbstractFor gas hydrate production, gas hydrate-bearing sediments should be depressurized below the gas hydrate equilibrium pressure. Gas hydrate-bearing sediments are compacted during the depressurization process because additional effective stress evolves due to a decrease in pore pressure. The compaction of a gas hydrate reservoir can lead to several geotechnical problems such as the destabilization of the production well, settlement of the seafloor installation, or slope failure of the production site. Thus, it is important to determine the compression characteristics of gas hydrate-bearing sediments and the geotechnical behavior of gas hydrate-bearing sediments during the gas hydrate dissociation induced by the depressurization. In this study, gas hydrates were synthesized in remolded sediment samples that were originally cored from a hydrate occurrence region in the Ulleung Basin, the East Sea, offshore Korea. The volumetric strain (or change of void ratio) of gas hydrate-bearing sediment samples were measured for different gas hydrate saturations and under different vertical effective stresses. The experimental results reveal the relation between compression (or the slope of a normal consolidation line) of gas hydrate-bearing sediments and gas hydrate saturation. Experimental data for compression indices of gas hydrate-bearing sediments can be applied to numerical modeling for a geotechnical stability analysis of gas hydrate-bearing sediments.
Earthquake Response of Pipelines on Submarine Slopes
Authors: Kaynia Amir M. , Dimmock Paul , Senders Marc 
Published: June 2014

Abstract
With recent trends in the offshore industry to move to deeper water, the response of submarine slopes has become a major geo-hazard issue partly due to the consequences for pipelines traversing the slopes. The dynamic and permanent displacements of the slope can exert axial loads and large bending moments on the pipeline. A fully integrated nonlinear dynamic analysis of pipeline-slope response under earthquake loading is impractical due to the spatial extent of the model and complications of pipe-soil interaction. The objective of this paper is to present a numerical model for this problem by a sub-structuring approach whereby the response of the pipeline is computed in two steps. In the first step, the dynamic response of the slope is computed independently of the pipeline, and in the second step, the interaction of the pipeline with the soil is analyzed using a model of the pipeline on distributed strain-softening soil springs. The input motion in the latter analysis is the asynchronous acceleration time histories computed on the surface of the slope along the pipeline in the first step. The computational model developed for this purpose, Quiver_pipe, is the result of research in the Joint Industry Project (JIP) Earthquake Effects in Deep Water.
Reliability Analysis of Lazy Wave Steel Catenary Riser (LWSCR) Using Real-Time Monitoring Data
Authors: Zhang Libang , Wu Chunfa , Liu Liming , McQueen Mark 
Published: June 2014

Abstract
Lazy Wave Steel Catenary Riser (LWSCR) is a relatively new type of configuration through the introduction of buoyancy modules for a certain length of the suspended riser for deep-water application. The benefits of this configuration includes the lowering of riser stress and fatigue at the top end and touch down area, making this an attractive concept. However, reliability analysis of LWSCR is scarce due to its very short application history and it is the purpose of this paper to investigate:Use of real-time monitoring field data from the Gulf of Mexico (GoM) in 2012, combined with a Finite Element Method (FEM) tool to calculate the reliability of the LWSCR;other conventional reliability methods, such as Monte Carlo simulation; andthe implication/impact of real time monitoring for assessing the riser integrity.The method proposed in this paper creatively integrates the concepts of Response Surface Method (RSM), FEM, and First Order Reliability Method (FORM). In general, the reliability analysis of nonlinear risers in the time domain is very challenging. Since the limit state function of a nonlinear dynamic riser system is implicit, RSM is used to approximate the limit state function and FORM used to calculate the corresponding reliability index, coordinates of the design point, and the sensitivity indexes for the random variables involved in the problem.The reliability estimation procedure is given in a form that will allow the basic ideas of the 1st and 2nd order reliability methods to be demonstrated. Using these methods allows variable sensitivity estimates for low computational cost to be made. The proposed procedure show good agreement over a range of probability distributions for the input random variables and for various complexities of the limit state functions.
How Waves can Significantly Impact Performance of Amine Unit Installed on a FLNG?
Authors: Weiss C. , Huguet E. , Magné-Drisch J. , Alix P. , Perdu Gauthier , White G. 
Published: June 2014

To conquer the current FLNG challenge, experts have to answer the question " What effect does the movement of the ship have on the amine process?". It is necessary to rely on accurate knowledge of the impact of the floating support movement on the towers operation, to first secure then optimize the design of the process units. Indeed both flooding and internals efficiency will significantly impact the towers sizing (diameter and height) and thus the whole FLNG project.
It is a complex problem to be able to take into account the multitude of factors such as liquid viscosity, height of packing, diameter of column, acceleration, liquid/gas flowrate, type of packing, and motions imposed on the system. After first years of work when they completed an extensive review of bibliographic data to build an early model of maldistribution based on a theoretical approach, Total, Prosernat and IFPEN have now performed more than one year research and development at Heriot-Watt University to model mass transfer and hydraulics of a tilting, moving tower. To assess the impact of experimental column diameter and to be in position to scale-up the results, two columns have been used and will be described.
The program has included both static and motion tests with varying periods and angles, at different liquid loads to map the distortion of liquid distribution at adjustable heights of packing. The data now acquired has shown, depending on operating conditions, a significant impact on liquid distribution in the packing bed, leading to differentiated wetted zones, including dry and overloaded areas. Some examples will be given to illustrate the impact on tower efficiency and the corresponding tower oversizing based on the results of test campaign.
Corrosion Testing of Deepwater Tubing Materials under Extreme Pressure and Temperature Conditions
Authors: Huang J. , Guraieb P. , Yan C. , Contreras E. , Tomson M. , Tomson R. 
Published: June 2014

Abstract
Prediction and prevention of scale and corrosion at extreme high pressure and temperature (xHPHT) is important to reduce environmental risk, improve human safety, and for production security for Gulf of Mexico (GOM) ultra deepwater (UDW) oil and gas production. In order to develop the methodology and prediction models needed for xHPHT corrosion, scale formation, inhibition, and the next generation of fluid modeling, this research was funded by RPSEA to study corrosion and scale at extreme pressure and temperature.
This paper presents the corrosion experimental work conducted at xHPHT and high total dissolved solids (TDS) conditions in both a static autoclave reactor and a flow-through apparatus. The corrosion behavior of different alloys used for deepwater production tubing in two types of synthetic brines which simulated two UDW well conditions were studied.
Reliable and feasible apparatus and procedures were developed for the corrosion study at extreme pressure, temperature and TDS conditions. Vertical scanning interferometry (VSI) was explored and found to be a powerful tool for localized corrosion analysis of different surface shapes (e.g., flat or curved).
Deepwater Reverse-Circulation Primary Cementing: Applicability and Technical Path Forward for Implementation
Authors: Wreden C. , Watters J.T. , Giroux R. , Nikolaou M. , Macfarlan K. , Richardson D.A. 
Published: June 2014

Abstract
A two-year government funded project is being conducted to evaluate the viability and applicability of Reverse-Circulation Primary Cementing (RCPC) in deepwater wells. This project focuses on the identification of technical issues that must be addressed before routine RCPC operations can occur in deepwater wells, and a recommended path forward to full evaluation of the viability of this placement technique in deepwater. Analysis includes numerical models and simulations, mechanical placement controls, cementing materials, and operational challenges.
While RCPC has been used on land and on a few shallow water offshore wells, it has not yet been fully evaluated for use in a challenging deepwater environment. The application of RCPC to deepwater wells is expected to reduce bottom-hole circulating pressures and prevent lost circulation during cementing, as well as increase safety, environmental sustainability, zonal isolation, and improve cement seals.
Standard commercially available software packages are unable to directly model the flow path through the complex configuration of a deepwater reverse-circulation cementing process. A multi-physics finite-element software package has been used to develop a model to predict temperatures and pressures during the reverse-circulation cementing process. Evaluation of mechanical placement controls has found that a major challenge will be the development of a switchable crossover between a conventional and reverse flow path, and the modification of float equipment. Also, with the application of RCPC it is anticipated that the design methodology of cementing fluids may be affected by changing the placement method.
One major challenge in deepwater cementing is the narrow formation fracture gradient, so the application of RCPC has clear beneficial potential. By lowering the Equivalent Circulation Densities (ECDs) during the job, the risk of fracturing the formation and lost-circulation is decreased. Less fluid lost to the formation during placement can potentially lead to higher tops of cement (TOC) and improved cement bonding and zonal isolation.
Characterization of the Slope-destabilizing Effects of Gas-charged Sediment via Seismic Surveys
Authors: Morgan Eugene , Vanneste Maarten , Vardy Mark 
Published: June 2014

Abstract
Finneidfjord, Norway has a history of submarine slope failure and hosts areas of buried, gas-charged sediment. Using shipboard seismic survey data from Finneidfjord, we illustrate how novel seismic data processing techniques can yield estimates of geotechnical properties of this gas-charged sediment: gas saturation (concentration) and excess pore pressure as well as their uncertainty. This data processing involves two steps:estimate the amount of seismic attenuation that a gas-bearing layer creates, andfit a wave attenuation model to the observed attenuation. We accomplish the first step using a wavelet-based spectral ratio approach, and find the seismic quality factor (inversely related to attenuation) from the change in amplitude spectra across the gas layer. The novelty of this paper really comes in the second step, where we create a Bayesian hierarchical model that combines a wave attenuation model with a spatial random (Gaussian) process model. The advantage of this combination is that our estimates of the gas properties not only must conform to the observations of attenuation (quality factor), but must also smoothly vary over space, as one would expect of any natural process. Ultimately, we end up with posterior distributions of gas properties at points throughout our gas-bearing layer, which give us estimates of parameter values and a sense of uncertainty about these estimates. We find good performance and agreeable values for gas saturation, but the model shows weak sensitivity to pressure, leaving large uncertainty in any excess pore pressure estimates. Implications for slope stability at Finneidfjord are discussed.
Significant ageing effects for axially loaded piles in sand and clay verified by new field load tests
Authors: Karlsrud Kjell , Jensen Tor Georg , Lied Ellen Katrine Wensaas , Nowacki Fritz , Simonsen Arne Schram 
Published: June 2014

Abstract
The paper describes key results from a series of new load tests to verify the impact of time or ageing on the axial bearing capacity of driven tubular steel piles. Load tests in two different sand deposits (a silty fine loose sand deposit and a medium dense, medium sand deposit), and four different clay deposits (low and medium plastic normally consolidated clay, over consolidated glacial clay, and a very highly plastic and over consolidated clay) were undertaken. Six tubular test piles were driven at each test site, with diameter 400 to 500 mm and length around 20 m. The piles were loaded to failure typically 1, 3, 6, 12 and 24 months after pile driving. At both sand sites, the shaft friction approximately doubled from the 1 month to the 12 months tests, but tended to level off after that. The ageing effect for piles in clay vary with the clay type, and comes in addition to the normal set-up due to dissipation of excess pore pressures. After 2 years, the gain in capacity range from a factor of about 1.1 to 2.0 compared to the capacity after full re-consolidation. The tests in the low-plastic low-OCR clay deposit showed the largest gain, and the tests in the highly plastic high OCR clay deposit the smallest. The study also revealed that repeated load testing on the same pile to failure can give both lower and higher capacity than first time testing, and therefore, can lead to misleading interpretation of ageing effects. One pile at each test site, was subjected to sustained loading at 60 % of the assumed failure load before being loaded to failure after 2 years. The impact of such sustained loading was generally to increase ageing effects for piles in clay, and reduce ageing effects for piles in sand. The overall results confirms that ageing effects are a significant positive factor to account for in future pile design practice.