bluuebunny/crossref_metadata_2025_split huggingface dataset:
Integrated Approach for Successful Well Abandonment Under Challenging Well Conditions – A Case Study
Authors: Isgenderov Islam , Osayande Victor , Nafikova Svetlana , Prasetyo Fajar Budi , van El Wouter Alexander 
Published: March 2021

Abstract
Emerging technologies, stringent permanent well abandonment regulations, and increasing well complexity affect the way we execute well intervention operations. One of the major operators in the Netherlands had an objective to set underbalanced cement plugs in brine across a deviated section using managed-pressure equipment to overcome high reservoir bottomhole pressure. The project involved several challenges: large-diameter production casing with a requirement to maintain high shut-in wellhead pressure, complex wellbore geometry, operations from a workover rig with zero discharge allowance, corrosive salt environment, and small cement slurry volume. These challenges had to be addressed to complete well abandonment to minimize safety risks, maximize efficiency, and achieve compliance with industry standards and regulatory requirements.
This paper discusses two case studies involving underbalanced pump-and-pull and conventional balanced plug placement techniques. Thorough analysis and risk assessment, engineering design approach, comprehensive laboratory testing, and fit-for-purpose surface equipment and downhole tools enabled flawless job execution and placement and achievement of long-term zonal isolation. The first well-barrier elements were successfully verified by tagging and pressure testing in both cases.
Results of this study include the following observations and conclusions: Managed-pressure cementing was proven to be an ideal solution for a well abandonment in a reservoir environment of high bottomhole pressure.Highly magnesium-resistant cement slurry design should be considered when setting cement plugs across an extremely corrosive salt environment.Successful verification of the first well-barrier element simplifies operations for subsequent cement plugs.
Cost-effective solutions for permanent well abandonment under challenging downhole conditions attracts increasing interest from petroleum engineers due to increasing well complexity and low oil prices that challenge the economics of wells, leading to abandonment. The current paper describes the challenging conditions under which the wells had to be abandoned, thorough analysis of the risks involved, and an effective solution. The design strategy, execution, evaluation, and results for these two wells are discussed in detail and will help to guide success and solve problems related to permanent well abandonment under similar challenging conditions.
Multi-Trajectory Hydraulic Model for More Accurate Geosteering Constraints
Authors: Alyaev Sergey , Daireaux Benoit 
Published: March 2021

Abstract
At the well-planning stage target selection usually accounts for drillability. However, during geosteering operations the drilling constraints are not updated and some fixed limits in terms of maximal inclination, dogleg severity, etc., are used instead. We demonstrate a methodology that uses fast physical models of the drilling hydraulics to calculate constraints and costs for geosteering dynamically during an operation.
In field development, many companies have adopted workflows that use ensemble-based methods for decision support. A real-time variation of such a decision support system (DSS) has been recently proposed for geosteering. The DSS is capable of optimization full well trajectories across all realizations of the earth model and can consider multiple objectives and constraints simultaneously. We present a method that makes steady-state hydraulic computations for all possible trajectories ahead-of-bit simultaneously at a low added cost. The output of the computation can provide more precise constraints (geo-pressure margins and cuttings transport) and cost estimates for the DSS.
In this paper we focus on verification and testing of the proposed multi-trajectory hydraulic model (MTHM). Discretization of the model acts as a trade-off between the preciseness of the computation and the computational speed. On our benchmark cases, a simulation that computes the hydraulic parameters for all trajectories with acceptable errors is fast enough for real-time geo-steering applications. Furthermore, we present a case based on data from the Norwegian Continental Shelf for which we demonstrate how hydraulic computations would influence the decisions of steering and stopping. Applying the DSS with the MTHM allows to precisely update the allowed steering interval, thus achieving safe operation while maximizing the expected well profit.
We emphasize that integration of the drilling processes modelling as part of the decision support for the geosteering operation enables better decisions. This is facilitated by the digitalization of the oil industry, but still requires development of new approximate models of the drilling processes. This paper demonstrates the MTHM as an initial step towards integration of drilling and geosteering modelling.
Analysis Behind Casing to Assess Zonal Isolation and Casing Deterioration in a High Pressure Exploratory Well - ABC to Z of Well Integrity Barrier Evaluation
Authors: Ahmed Hassaan , Khan Mohammad Rasheed , Bari Abdul , Rashid Kamran , Ali Syed Dost , Dhawan Sandeep , Zubair Talha , Anjum Usman , Sookram Neil 
Published: March 2021

Abstract
The UHP exploratory well subject of this study faced with myriad challenges, including fishing, side-tracking, and other undesirable incidents with consequences to the 9-7/8" production casing. Torque and drag analysis, preliminary casing wear simulations, and actual drilling parameters pointed towards multiple uncertainties concerning barrier integrity. Consequently, a multi-physics evaluation was conducted including well-integrity logs in a combination of thickness-mode with flexural-mode of the casing. Signals from these independent measurements are then processed to provide robust interpretation of solid-liquid-gas behind casing using acquired flexural attenuation and acoustic impedance data. In addition, casing wear is quantified by thickness changes measured through the resonance frequency of the waveform and represented in the form of a joint-by-joint corrosion summary, reporting the average metal loss. Furthermore, propagation of flexural wave-fronts as it leaks to the third interface is tracked to produce a unique image of the annulus geometry in terms of casing eccentricity and acoustic velocity of the medium. Subsequently, the former, provides a quantifiable, unique in-situ casing standoff measurement to be used for centralization evaluation.
Application of the developed data-integrated workflow allowed for comprehensively analyzing well integrity barrier condition. Cement barriers were assessed with confidence by flexural imaging, which were difficult to determine solely with pulse-echo. Additionally, annulus imaging using third interface-echo (TIE) helped in characterizing the potential causes of casing wear and quality of cement behind casing by providing actual in-situ casing standoff. It was observed that casing wear was at the low side of the wellbore where the casing had the least standoff as shown by flexural waveform TIE arrivals. Moreover, high percentage of metal loss was correlated to regions with centralization lower than 40-50%. Integration of these results with casing side forces and remaining casing strength (under worst case scenario) was performed to evaluate casing endurance for future drilling, production, and injection operations.
Oil and Gas Drill Bit Technology and Drilling Application Engineering Saves 77 Drilling Days on the World’s Deepest Engineered Geothermal Systems EGS Wells
Authors: Cardoe Jennifer , Nygaard Gunnar , Lane Christopher , Saarno Tero , Bird Marc 
Published: March 2021

Abstract
An Engineered Geothermal System (EGS) pilot project was commissioned to prove the economic viability of an industrial scale geothermal heat plant in Finland. The project aims to generate 40 MW of emission free heat energy, supplying up to 10% of the city of Espoo’s district heating needs. Two wells of 6400 m MD and 6213 m MD (measured depth) were drilled through formations of hard, abrasive granitic gneiss with maximum measured 560 MPa UCS (unconfined compressive strength). Typical dull conditions of lost and worn cutting structure and gauge diameter wear of between 3/16-in to ¼-in contributed to excessive torque, stuck incidences, low rate of penetration (ROP) and difficulties achieving build rate. To address these drilling challenges, this paper explores the interplay between new cemented carbide compact technology, drill bit design, and drilling parameter road mapping.
The directional section of the first well was drilled with an average ROP below 2 m/hr and run length averaging 56 m per bit. The well took 246 drilling days and 44 BHAs (bottom hole assemblies) to achieve TD (total depth). Between the first and second well an application specific drill bit design package and step-wise parameter program were implemented. Design enhancements included improved gauge protection, bit hydraulics for minimizing cone erosion and subsequent TCI (tungsten carbide insert) compact loss. Novel hybrid TCI materials technology was introduced having a 100% improvement in wear resistance and durability as compared with conventional grades, to drill these hard and abrasive granitic formations.
New BHAs and drilling plan were selected based on the bit design selection to reduce wear on BHA components, improve directional control and reducing drilling dysfunctions. Once these factors were under control, a low risk approach to extending the bit revolution limits (krev) for the roller cone sealed bearings could be implemented based on downhole parameters and previous bit dulls, leading to longer run lengths.
The combination of bit design and material enhancements with a properly selected BHA and drill plan increased run lengths and ROP. The second well’s 8.5-in directional section was drilled with a 13% increase in average ROP and a 69% increase in average run length without exceeding krev limits. Well on well, a 77 day reduction in AFE (authorization for expenditure) was realized.
We demonstrated the combination of oil and gas bit and BHA design, drilling plan, and new cutting material capabilities can reduce EGS well construction costs in order to make these renewable energy sources economical.
Drill Bit Failure Forensics using 2D Bit Images Captured at the Rig Site
Authors: Ashok Pradeepkumar , Chu Jian , Witt-Doerring Ysabel , Yan Zeyu , Chen Dongmei , van Oort Eric 
Published: March 2021

Abstract
Identifying the root cause of damage of a pulled bit as soon as possible will aid preparation for future bit runs. Today, such bit damage analyses are often anecdotal, subjective and error-prone. The objective of this project was to develop a software algorithm to automatically analyze 2D bit images taken at the rig site, and to quickly identify the root cause of bit damage and failure.
A labelled dataset was first created whereby the damage seen in bit photos was associated with the appropriate root cause of failure. Particular attention was given to the radial position of the cutters that were damaged. Using the 2D bit images (which can be obtained at the rig site), a convolutional neural network along with other image processing techniques were used to identify the individual cutters, their position on the bit, the degree of wear on each cutter. A classifier was then built to directly identify root cause of failure from these images.
This work utilized a large dataset of wells which included multiple bit images, surface sensor data, downhole vibration data, and offset well rock strength information. This dataset helped relate the type of dysfunction as seen in the downhole and surface sensor data to the damage seen on the bit. This dataset however only covered some types of dysfunctions and some types of bit damage. It was therefore augmented with bit images for which the type of failure was determined through analysis by a subject- matter expert. A classifier was subsequently developed which properly identified the root causes of failure when the bit photo quality met certain minimum standards. One key observation was that bit images are not always captured appropriately, and this reduces the accuracy of the method.
The automated forensics approach to Polycrystalline Diamond Compact (PDC) bit damage root cause analysis described in this paper can be performed using 2D bit photos that can be easily captured on a phone or camera at the rig site. By identifying the potential root causes of PDC damage through image processing, drilling parameters and bit selection can be optimized to prolong future bit life. The algorithm also enables uniformity in bit analysis across a company's operations, as well as the standardization of the process.
Association Between Serum Chemokine Cc-motif Ligand 17 and Prognosis of Patients at Risk for Coronary Heart Disease
Authors: Tian Ran , Feng Si-Qin , Wang Lei , Wang Yi-Fei , Wang Yi-Yang , Chen Yu-Xiong , Wang Hui , Liu Hong-Hong , Zhang Shu-Yang 
Published: March 2021

Abstract
BackgroundIt has been reported chemokine CC-motif ligand 17 (CCL17), an inflammatory mediator modulating T cells function to affect formation and stableness of atherosclerotic plaque and is associated with the severity of coronary heart disease (CHD). This research aims to further explore the relationship between serum CCL17 and the prognosis of patients at risk for CHD.MethodThis study retrospectively enrolled 495 patients receiving coronary angiogram at Peking Union Medical College Hospital from January 2012 to December 2013. Serum CCL17 was measured on admission and annual routine telephone follow-up was carried out till December 2020. The prognosis of patients was evaluated by the incidence of major adverse cardiovascular events (MACE). Cox survival analysis have been applied for univariate and multivariate models setting., Machine learning and data imbalance methods were also added to improve the model performance.ResultsCompared with patients with low serum CCL17 level, patients with medium and high serum CCL17 demonstrated elevated risk to develop MACE, with the hazard ratio (HR) being 4.53 [95% confidence interval (CI) 2.08-9.88] and 6.38 (95% CI 3.07-13.28) respectively. CCL17 served as an independent risk factor to predict the incidence of MACE and the addition of CCL17 to the baseline risk model significantly increase the predictive ability for MACE (Area under curve: baseline risk model 0.803±0.021 vs baseline risk model+CCL17 0.836±0.021, p for comparison<0.001).ConclusionsElevated CCL17 functions as an independent predictor for MACE in patients at risk for CHD and the potential mechanisms deserved more exploration in the future.
Percutaneous Radiofrequency Rhizotomy for Prompt Pain Management in Peculiar Cases of Trigeminal Neuralgia
Authors: Zaragita Nadya , Prasetya Mustaqim , Sulistyanto Adi 
Published: March 2021

Abstract
Background: Trigeminal neuralgia is a neurological condition characterized by episodes of intense stabbing or electric shock-like pain caused by disorder of the fifth cranial nerve. Most TN cases are caused by vascular compression, but rarely it can be caused by tumor or autoimmune diseases (e.g. multiple sclerosis). Case presentation: We report two rare cases of secondary trigeminal neuralgia caused by tumors. The 1st patient is a 38 year old male with intractable pain and MRI result suggestive of trigeminal schwannoma at the left cerebellopontine region, while the 2nd patient is a pregnant 26 year old female with MRI result suggestive of an epidermoid cyst at left cerebellopontine region compressing the trigeminal and and facial nerve. Surgical option was declined by both patients because of the associated risks although immediate pain relief was needed. Percutaneous radiofrequency rhizotomy (PRFR) was chosen for prompt pain management and results showed immediate pain relief. Conclusion: We conclude that PRFR is an effective option for pain management in secondary trigeminal neuralgia patient in whom primary treatment for the underlying cause is not feasible.
Impact of relative humidity and water availability on the life history of the predatory mite Amblyseius swirskii
Authors: San Phyu Phyu , Tuda Midori , Takagi Masami 
Published: March 2021

Abstract
The predatory mite Amblyseius swirskii (Athias-Henriot) (Acari: Phytoseiidae) is currently used as an efficient biological control agent of thrips, whiteflies and spider mites, which are economically damaging pests of ornamental plants and vegetable crops grown in greenhouses and fields worldwide. Currently, the effects of relative humidity (RH) and water availability on the optimal growth of A. swirskii are unknown. Here, we test the combined effects of different levels of RH (33%, 53%, 73% and 92%) and water availability on the development and reproduction of male and female A. swirskii feeding on the dried fruit mite, Carpoglyphus lactis (Linnaeus). While eggs failed to hatch at 33% RH, the survival rates of the immature stages at ≥ 53% RH increased solely in response to water availability and not due to changes in RH. Regarding growth and development, low RH extended the egg–adult duration and pre-oviposition period. We also found that the negative effects of low RH on adult longevity and fecundity were partially or completely eliminated when drinking water was available. For the life table parameters, the highest values of net reproductive rate (R0) and intrinsic rate of natural increase (r) were achieved at the highest RH when drinking water was available. Overall, water availability mitigated the negative effect of low RH on female reproduction, and female development was more sensitive to water availability than male development. Lastly, a comparison of similar research on A. swirskii suggested that water availability and RH are more influential on r than food source or temperature.
Coastal wetlands mitigate storm flooding and associated costs in estuaries
Authors: Fairchild Tom , Bennett William , Smith Greg , Day Brett , Skov Martin , Möller Iris , Beaumont Nicola , Karunarathna Harshinie , Griffin John 
Published: March 2021

Abstract
As storm-driven coastal flooding increases under climate change, wetlands such as saltmarshes are held as a nature-based solution. Yet evidence supporting wetlands’ storm protection role in estuaries - where both waves and upstream surge drive coastal flooding - remains scarce. Here we address this gap using numerical hydrodynamic models within eight contextually diverse estuaries, simulating storms of varying intensity and coupling flood predictions to damage valuation. Saltmarshes reduced flooding across all studied estuaries and particularly for the largest – 100-year – storms, for which they mitigated average flood extents by 35% and damages by 37% ($8.4M). Across all storm scenarios, wetlands delivered mean annual damage savings of $2.7M per estuary, exceeding annualised values of better-studied wetland services such as carbon storage. Spatial decomposition of processes revealed flood mitigation arose from both localised wave attenuation and estuary-scale surge attenuation, with the latter process dominating: mean flood reductions were 17% in the sheltered top third of estuaries, compared to 8% near wave-exposed estuary mouths. Saltmarshes therefore play a generalised role in mitigating storm flooding and associated costs in estuaries via multi-scale processes. Ecosystem service modelling must integrate processes operating across scales or risk grossly underestimating the value of nature-based solutions to the growing threat of storm-driven coastal flooding.
Enhanced Cercosporin Production by Co-culturing Cercospora Sp. JNU001&nbsp;With Leaf-Spot-Disease-Related Endophytic Bacteria
Authors: Zhou Tingan , Yu Shiyu , Hu Yifan , Zhang Yan , Song Yuechen , Chu Jieyu , Liu Changmei , Rao Yijian 
Published: March 2021

Abstract
Background: Owing to the excellent properties of photosensitization, cercosporin, one of naturally occurring perylenequinonoid pigments, has been widely used in photodynamic therapy, or as an antimicrobial agent and an organophotocatalyst. However, because of low efficiency of total chemical synthesis and low yield of current microbial fermentation, the limited production restricts its broad applications. Thus, the strategies to improve the production of cercosporin were highly desired. Besides traditional optimization methods, here we screened leaf-spot-disease-related endophytic bacteria to co-culture with our previous identified Cercospora sp. JNU001 to increase cercosporin production. Results: Bacillus velezensis B04 and Lysinibacillus sp. B15 isolated from leaves with leaf spot diseases were found to facilitate cercosporin secretion into the broth and then enhance the production of cercosporin. After 4 days of co-culture, Bacillus velezensis B04 allowed to increase the production of cercosporin from 128.2 mg/L to 984.4 mg/L, which was 7.68-fold of the previously reported one. Lysinibacillus sp. B15 could also enhance the production of cercosporin with a yield of 626.3 mg/L, which was 4.89-fold higher than the starting condition. More importantly, we found that bacteria B04 and B15 employed two different mechanisms to improve the production of cercosporin, in which B04 facilitated cercosporin secretion into the broth by loosening and damaging the hyphae surface of Cercospora sp. JNU001 while B15 could absorb cercosporin to improve its secretion.Conclusions: We here established a novel and effective co-culture method to improve the production of cercosporin by increasing its secretion ability from Cercospora sp. JNU001, allowing to develop more potential applications of cercosporin.
The structural transformation comparison of the human Prion protein mutants V176G, E196A, and I215V by using molecular dynamics simulation
Authors: Jomah Ashraf Fadhil , Parvizpour Sepideh , Razmara Jafar , Shamsir Mohd Shahir 
Published: March 2021

Abstract
The point mutations in the gene coding of prion protein (PrP) originate human familial prion protein (HuPrP) diseases. Such diseases are caused by several amino acid mutations of HuPrP including V176G, I215V, and E196A located at the second, third native helix and in their loop, respectively. Determining the transition from cellular prion protein (PrPc) to pathogenic conformer (PrPSc) in the globular domain of HuPrP that results in pathogenic mutations is the key issue. The effects of mutation on monomeric PrP are detected in the absence of an unstructured N-terminal domain only. A MD simulation for each of these wild type mutants is performed to examine their structure in the aqueous media. The structural determinants are discerned to be different for wild-type HuPrP (125–228) variants compare to that of HuPrP mutations. These three mutations exhibiting diverse effects on the dynamical properties of PrP are attributed to the variations in the secondary structure, solvent accessible surface areas (SASAs), and salt bridges in the globular domain of HuPrP. High fluctuations that are evidenced around residues of the C-terminus of the helix 1 for V176G cause Gerstmann-Straussler-Scheinker (GSS) syndrome. Conversely, the occurrence of fluctuations around residues of helix 2, helix 3, and the loss of salt bridges in these regions for E196A and I215V mutants is responsible for Creutzfeldt-Jakob disease. Furthermore, small changes in the overall SASAs mutations strongly influence the intermolecular interactions during the aggregation process. The comparative results in this study demonstrate that the three mutants undergo different pathogenic transformations.