bluuebunny/crossref_metadata_2025_split huggingface dataset:
Real-Time Monitoring and Interpretation of Wireline Formation Testing Using Ensemble Kalman Filter
Authors: Elshahawi Hani , Filippov Andrey 
Published: April 2019

Abstract
The ensemble Kalman filter (EnKF) algorithm is an elegant and effective method to optimize model parameters based on differences with predictions of model and measurement data. Great progress has been accomplished using EnKF for data assimilation within reservoir modeling during the last two decades. A typical example where data assimilation is necessary is history matching—the process of adjusting the model variables to account for observations of rates, pressure, saturations, and other variables. In contrast, much less attention has been given to flow model optimization for other workflows, such as drilling, production, flow assurance, and well testing.
Providing two examples of applying the EnKF for real-time quantification of sensor-generated data is the aim of this paper. These examples include the analysis of the declining production curve and zonal pressure sensor data for evaluating matrix permeabilities and processing the multichannel optical to monitor the cleanup of hydrocarbon fluid samples during formation-tester sampling.
Additionally, how the EnKF algorithm can be successfully applied to segmented multichannel sensor field data obtained from multichannel optical density sensors exhibiting the gradual transition from oil-based mud (OBM) filtrate to native formation fluid during formation-tester sampling stations is discussed. A simple algebraic proxy model is used to predict the decline of the volumetric fraction of OBM filtrate with time during formation-tester sampling.
To implement and test the algorithm, a proof-of-concept MATLAB code was developed. Synthetic (simulated) pressure flow rate data were used for the production decline case while the actual field data from eight channel optical sensors were used for the formation-testing case. Model runs were performed in 50 to 60 combinations of model parameters, which were normally distributed around the best-guess values at the initial step. For both cases, only two to three iterations of the algorithm were sufficient to obtain values of the matching parameters.
Advisory Hull Monitoring System for the Bonga FPSO
Authors: Aalberts Pieter , Ibekwe Achinike , Hageman Remco , Oguntola Gbolagade , Izuchukwu Josiah , Sorensen Kjeld , Nadathur Varadarajan , van Vliet Renate 
Published: April 2019

This paper describes the implementation of the Advisory Hull Monitoring System (AHMS) onboard the existing Bonga FPSO (Nigeria) during operations and production. AHMS has been developed for FPSOs in the Monitas Joint Industry Project as a fully automated system, which explains and advises on the fatigue lifetime consumption of the hull of FPSOs. The explanations and advice offered are based on a comparison between the design and the actual predicted lifetime consumption by replacing the design parameters including environmental and operational conditions with the measured data. The system differentiates between the contributions of environmental and operational conditions as well as hydro-mechanic and structural responses. The AHMS system comprises hardware and software for smart data gathering and processing. AHMS hardware includes strain- type sensors on deck and inside the Water Ballast Tanks (WBTs) and/or void spaces and interfaces with external systems including the Computer Loading Instrument (CLI), Gyro and metocean system. AHMS has generally been installed onboard newly built floaters including the Usan FPSO (Nigeria), Clov FPSO (Angola), Ichthys FPSO (Australia) and Moho Nord FPU (Congo). Being in operation since 2005, the Bonga FPSO has lived 14 of its 20-year design life. Given the constraints inherent in her design, deployment of the AHMS for the FPSO's hull fatigue life monitoring therefore presented unique installation challenges to overcome as would be expected for ageing brownfield assets. To add to this challenge, the installation was carried out during production and so required strict adherence to the stringent safety requirements of Simultaneous Operations (SIMOPs) on a live plant. This paper describes in detail, the AHMS hardware, the complexity and challenges of their installation for the Bonga FPSO and highlights lessons learned for typical brownfiled retrofit of this nature.OCTOPUS MONITAS, the software of the AHMS system for the smart data processing, calculates onboard fatigue lifetime consumption of the hull and explains the differences against design predictions. Methodology of the software is herein described, and the first set of measurements taken from the Bonga FPSO as well as preliminary results produced by the software are similarly presented.
Optimization of CO2 Foam EOR Processes: A Case Study from Lab-scale Model Fit to Field-Scale Development Planning
Authors: Izadi Mohammad , Nguyen Phuc H. , Fleifel Hazem , Ortiz Maestre Doris , Kam Seung I. 
Published: April 2019

Lisama field, located in the eastern part of the Middle Magdalena Valley Basin in Colombia, was discovered in 1935 and estimated to hold approximately 0.25 billion STB of oil in place. Mainly consisting of two primary sandstone formations, the field moves gradually from the primary to the secondary and tertiary recovery methods. Injection of water and gas is considered as a possible solution in the next phase. This study performs a simulation study by using CMG STARS for a sector with an inverted 5-spot pattern to evaluate a wide range of development strategies for gas-water co-injection and foam treatments.
After performing reservoir simulations varying gas and liquid fractions (from 100% CO2 injection to 100% liquid injection) at four different levels of gas mobility reduction (mobility reduction factor (MRF) = 1, 10, 100, and 1000 for no foam, low-strength, intermediate-strength and high-strength foam, respectively), this simulation study reveals the following findings. First, compared to gas-water injection with no foams, injection of foams can improve cumulative oil recovery and sweep efficiency significantly. Such a tendency is observed consistently at three high, intermediate, and low total injection rates tested. Second, the use of sweep-efficiency contours as a function of injection foam quality (fg, or 1-fw) and MRF, at given total injection rate, provides a useful insight to understand graphically how effective an injection strategy can be. If an MRF-vs.-fg coreflood experimental data is imposed on the contour plot, the results can assist important business and technical decisions about optimum field development planning. Third, if certain constraints exist in the field, they can be mapped out on the sweep-efficiency contour map to predict how the optimum injection strategy should change. In addition, the simulation results show that this field of interest has gravity-dominant environments such that the injection at wetter condition, with or without foams, can be viewed as a better injection strategy in general to obtain higher oil recovery. The business decision, however, can have the injection condition skewed depending on the costs of supercritical CO2 and surfactant solutions.
Automatic Geohazard Detection Using Neural Networks
Authors: Arogunmati Adeyemi , Moocarme Matthew 
Published: April 2019

Abstract
In this paper, we demonstrate the potential of neural networks in the automation of shallow geohazard detection and identification on seismic images. We discuss technical considerations and method limitations. The method used in this paper trains a neural network prediction model to automatically detect features in seismic images by estimating model parameters from a large set of input training images that have been manually interpreted. In this case, the independent variable is the seismic image and the dependent variable is the human interpretation. We used a separate test data set that was not used in training the model to validate our results. The novel approach and workflow presented in this paper is a significant advancement in geohazard detection and identification projects. The time taken to complete such a project using a conventional approach is significantly reduced – our model interprets entire seismic volumes in seconds with consistency, minimal human input and comparable accuracy.
Liuhua 11-1 FPSO & FPS Mooring System Life Extension Evaluation and Challenging Issues
Authors: Wang Huoping , Zhang Qinghe , Liu Yiyong , Mao Jiayou , Zhu Weiquan , Shen Hui 
Published: April 2019

Abstract
Mooring system life extension for offshore floating production installation has become a hot topic for offshore industry as more and more floating units approach the end of their design lives. Some mooring system life extension projects have already been completed successfully, there are still some issues upon which the mooring industry has not reached consensus, such as field inspection capability/accuracy, uninspected items assessment, component degradation assessment, and acceptance criteria for numerical evaluation. This paper demonstrates two mooring system life extension processes located at Liuhua (LH) 11-1 oil field, following ABS rules as well as industry best practices. It also presents the challenging issues met during this long period of operation, initiated in 2016 and to be completed by end of 2019.
Nanhai Shengli (NHSL) FPSO and Nanhai Tiaozhan (NHTZ) FPS are located in Liuhua 11-1 oil field. Both of the mooring systems were installed in 1995 with an originally designed life of 10 years, and already upgraded/replaced partially to extend their lives for continual safety operation. Thus, this is the second life extension for them, and some special challenges are presented. The upgrade of the mooring system is proposed based on inspection, testing, and analysis results for the existing mooring components. This paper focuses on some of the work that has been performed. These experiences may be helpful for the life extension of other similar mooring systems.
Driving Down Cost: A Case Study of Floating Substructure for A 10MW Wind Turbine
Authors: Udoh Ikpoto Enefiok , Zou Jun 
Published: April 2019

Abstract
Power generation costs must be competitive for the offshore wind industry to survive and advance consistently. It is widely believed that adopting high-capacity wind turbines (10 MW or higher) is an effective approach to reduce levelized costs of energy. Industry trends indicate that use of high-capacity turbines is imminent, and the suitability of existing floating substructure concepts is being challenged. This paper assesses characteristics of a floating substructure for supporting high-capacity turbines. A 10 MW wind turbine application with the floating structure concept in 100m water depth is investigated and verified by using aero-hydro-servo-elastic dynamic simulations. Environmental loads considered are wind, wave and current, and simulations are performed in time domain to capture interactions and non-linear responses. Wind loading on the RNA is modeled using turbulent wind fields, with turbulence intensities representative of offshore environments, whereas wind loads on the platform are captured using reliable wind load coefficients. Effects of a 10MW turbine on the nacelle, tower, platform and moorings are highlighted, and correlations between the responses are discussed. The responses are quantified and compared using power spectral densities (to delineate low, wave and high frequency effects) and extreme statistics. Comparisons discussed in this paper underscore the importance of adaptability of platform features to maintain favorable responses of floating substructures for high-capacity turbine applications. A hull steel efficiency indicator is adopted for the quick and simple measure of substructure hull efficiency. Findings of this study offer one solution to drive down the cost dramatically and provide insights for future developments.
A Novel Quasi-3D Landslide Dynamics Model: From Theory to Applications and Risk Assessment
Authors: Vanneste Maarten , Løvholt Finn , Issler Dieter , Liu Zhongqiang , Boylan Noel , Kim Jihwan 
Published: April 2019

Abstract
Submarine landslides can pose a significant threat to offshore installations and coastal communities. They can strike installations far from their origin and generate destructive tsunamis. To assess and quantify this hazard, it is necessary to be able to model their dynamics in complex submarine environments with realistic rheological input parameters.
Many submarine landslides involve cohesive visco-plastic soils, which can be described mathematically by rheological models such as the non-linear Herschel–Bulkley model. To model these events, accounting for complex bathymetry and rheological behavior, NGI has developed BingClaw. It incorporates buoyancy, hydrodynamic resistance and remolding, which are crucial for underwater landslide dynamics. BingClaw has been used to study the dynamics and tsunami generation of some of the largest and most complex submarine landslides in the world such as the Storegga Slide about 8000 years ago and the 1929 Grand Banks landslide and tsunami. In both cases, BingClaw provided a far more realistic description of both the landslide dynamics and the induced tsunami than other models. The link to the tsunami generation was used to better constrain the landslide dynamics.
Here, we demonstrate how BingClaw is used for geohazard applications, including attempts to hindcast past landslides directly relevant to these applications, as often rheological data are sparse or not available from a given site. We first present benchmark results comparing the landslide model with results from laboratory experiments. Then, we show comparisons between simulations and observed landslide run-out for both offshore and onshore applications. The onshore application provides additional well-controlled field studies for validation, in soils with high sensitivity. We also used BingClaw in an offshore/nearshore geohazard project, namely the Bjørnafjorden project offshore western Norway. There, we linked the run-out analysis directly to static and seismic slope stability evaluations, and the predicted run-out scenarios were used in the assessment of competing bridge concepts and their foundations in the deep fjord (around 560 m water depth).
These studies illustrate that this novel method, applicable for onshore and offshore geohazard assessments, can reliably reproduce field observations using realistic rheological parameters, which is important when estimating the risk posed by submarine mass movements, particularly with respect to the potential impact on infrastructure.
Deposition Mitigation in Flowing Systems Using Coatings
Authors: Pickarts Marshall A , Brown Erika , Delgado-Linares Jose , Blanchard Gabriela , Veedu Vinod , Koh Carolyn A 
Published: April 2019

AbstractIn pipelines, solid compounds including gas hydrates and asphaltenes may form/precipitate and accumulate on the pipe surface, leading to a gradual stenosis of the flowline. As a result, production may become increasingly difficult or possibly interrupted if mitigation efforts are not enacted. Typically, injected chemicals will either inhibit nucleation or dissolve already-formed deposits to restore original flow conditions back to the system; however, this can be a costly option. More recently, management strategies have been proposed where solids are handled in a controlled fashion rather than completely avoided. One such proposed management strategy as suggested for wall deposit formation is the use of coatings. Here, coatings can provide a low surface energy layer on the pipe wall, which restricts liquid and solid accumulation, allowing for a stable slurry flow through a system.This study utilized two material formulations within several experimental setups to probe their interactions with water, gas hydrate, asphaltene, and crude oil. The results serve as part of an ongoing investigation into a surface treatment formulation that can be tested on larger-scale, fully flowing systems, which could be ultimately implemented into real-world production scenarios. The first surface treatment is a water-based polymeric surface that displays repellency to both oil and water phases (omniphobic). Testing of this material consisted of water contact angle measurements and static asphaltene/crude oil deposition quantification at atmospheric conditions, as well as visual confirmation of hydrate deposition prevention at high pressures. Additionally, an experimental superomniphobic surface treatment, which displays elevated resiliency to both water and hydrocarbons, was also examined within the asphaltene/crude oil test as a comparison to the omniphobic surface treatment.Static contact angle results showed that the omniphobic surface treatment had reduced surface interaction with water droplets in air, increasing the low contact angles of corroded surfaces (0-31°) to slightly hydrophobic conditions of 91.5°. Additionally, rocking cells tests indicated that these omniphobic surface treatments may prevent gas hydrate deposition under high-pressure, semi-flowing conditions. Multiple tests found that formed hydrate agglomerants did not deposit for at least 48 and 72 hours. Finally, static deposition tests conducted in crude oil with forced asphaltene precipitation suggested that the omniphobic surface treatment displayed a resistance to both asphaltenes and crude oil when compared to untreated and superomniphobic surfaces.
Casing Wear Estimation Without a Baseline Log - A Distorted Ellipse Methodology
Authors: Chandrasekhar Sharat V , Anjos Jorel L , Frazão Leonardo E , Bonelli Rosane C , Percy Joseir G , Dos Santos Cleidilson M , Gasparetto Danilo , Lima Lorena B , Pilisi Nicolas 
Published: April 2019

The estimation of casing wear from USIT or Caliper logs requires a proper evaluation of the shape of the tubular inner surface prior to casing wear. In the absence of a viable baseline log, this shape must be deduced through analytical means. Manufacturing deviations from perfect circularity result in eccentricity and ovality, so that the pre-wear shape is in general, elliptical in nature. Owing to the fact that a standard ellipse may not be adequate to capture this shape in all situations, an approach using a distorted and shifted ellipse is proposed. The shift from the geometrical centerline of the ellipse co-ordinates in order to capture the effect of improper centralisation of the logging tool.
The approach uses a least-squares minimisation technique to determine the distorted ellipse parameters such that the overall radial discrepancies between the pre- and post-wear shapes are minimised. A multi-pass approach wherein detected wear grooves are censored results in better predictions of the pre-wear shape as was determined from several validation test cases with known wear groove depths. The methodology was also applied to an actual USIT log with over 20,000 stations with 72 radial measurements at each station. The methodology also enables the detection of true locations of high wear from spurious ones. As proposed, the method is also capable of using either internal radius or wall thickness as the evaluation metric, and is stable in the presence of significant noise in the measurements.
Alternative Material to be Applied in Oil Well Cementing Subjected to High Temperatures to Avoid Compressive Strength Retrogression
Authors: Araújo Romero Gomes da Silva , Freitas Julio Cezar de Oliveira , Costa Bruno Leonardo de Sena , Moreira Paulo Henrique Silva Santos , Silva Fabrício Pereira Feitoza da , Oliveira Yvis Henrique de 
Published: April 2019

Abstract
When Portland cement sheath is submitted to temperatures above 110 °C in oil well wellbore conditions, the compressive strength retrogression phenomenon is observed. This occurs due to the conversion of calcium silicate hydrate (C-S-H) to unstable phases, resulting in low compressive strength and high permeability. To minimize that compressive strength issue, guidelines suggests the addition of 35-40% BWOC (By Weight Of Cement) of an extra silica source to balance the relation CaO/SiO2 and convert it into more stable calcium silicate phases. Silica flour (SF) is the silica source worldwide used as anti-strength retrogression agent in cementing operations. The present work presents rice husk ash (RHA) as a sustainable silica source, in alternative to SF, for temperature of the environments where compressive strength retrogression is pronounced. Four compositions of cement slurries were tested: (i) a 15.6 ppg slurry with no silica addition (SF0); (ii) a 15.6 ppg slurry with 35% BWOC of SF addition (SF35); (iii) a 15.0 ppg slurry with 35% BWOC RHA addition (RHA-1) and (iv) a 14.5 ppg with 35% BWOC of RHA (RHA-2). The samples were submitted to 60 °C and 110 °C at atmospheric and 2,000 psi curing pressure, respectively, during 7 days. A uniaxial compression test was performed to evaluate RHA as anti-strength retrogression agent. All experimental procedures were performed in accordance to API RP 10B-2. X-ray diffraction (XRD), scanning electronic microscopy (SEM) and thermogravimetric analyses (TGA) were carried out to analyze the samples after temperature exposure. Results have shown that RHA samples developed more compressive strength in relation to the usual SF sample. Among the samples cured at 110 °C, RHA-1 presented the higher value of compressive strength (44.6 MPa), followed by sample SF35 (40.4 MPa) containing SF in its composition. The sample RHA-2 with 37.9 MPa of compressive strength was similar to SF35 and, as expected, the compressive strength of control sample SF0 was the lower with 28.3 MPa, due to the retrogression phenomenon. The samples cured at 60 °C showed the same tendency of 110 °C samples. XRD analysis showed the presence of typical stable crystalline phases such as xonotlite and tobermorite in cement samples containing RHA. The SEM images and TGA analyses were in accordance to XRD evaluations. As observed, RHA showed great potential as anti-strength retrogression agent even in weighted (15.0 ppg) or light weight (14.5 ppg) slurries. The sustainability of a renewable silica source makes the RHA an interesting alternative to the usual silica flour.