bluuebunny/crossref_metadata_2025_split huggingface dataset:
Successful Off Bottom Cementation of a Highly Deviated 4 ½ in Production Liner in UAE
Authors: Hamidzada Ahmedagha , Alaleeli Ahmed Rashed , Hassan Azza El , Tarsh Fatima Bin , Abdelkarim Islam 
Published: May 2021

Abstract
Cementing a highly deviated production liner is associated with cement placement challenge that can compromise zonal isolation. A major operator in UAE, was facing a challenge to cement 4 ½ in slim production liner set at + 5000 ft off-bottom. The corresponding 6 in. section was drilled with a relatively high mud weight in the range of 12 to 13 PPG. One of the main challenge was the risk of solids settling on the low side of the wellbore, making mud displacement difficult to achieve while cementing. Additionally, cementing off-bottom without an ECP in a highly deviated wellbore with multiple exposed production zones, further increased cement placement complexity. A holistic engineering approach was integrated to ensure successful zonal isolation. Wellbore parameters and fluid properties were critically evaluated.
To overcome off-bottom cementing and prevent slurry fallback risks, a weighted high viscosity pill with high yield point was placed as a temporary basement to support the cement column and isolate the reservoir during 4 ½ in liner job. After placement of the pill, the wellbore was observed for flow checks to ensure stable downhole conditions prior to displacing the drilling fluid across the liner interval to brine within the same density.
A centralization program was implemented to achieve more than 70% stand-off which required a minimum centralization pattern of two rigid centralizers per joint which helped minimize the presence of mud channels on the narrow side.
Effective mud removal was ensured through implementation of a spacer train in front of the cement. The first spacer was pumped with same mud density to reduce ECD followed by another advanced low invasion loss circulation spacer to mitigate losses as well as provide a sustained downhole rheology. A resilient, expandable and gas tight cement slurry, was selected to target long-term zonal isolation. Multiple hydraulic simulations were performed to optimize ECDs and ensure safe margins during placement
A CFD (computational fluid dynamics) model was utilized to simulate hydraulics, expected mud removal and fluids inter-mixing especially during liner rotation. In addition, the model simulated high-calculated torques based on flow restrictions through liner hanger assembly. Lack of mechanical liner movement was compensated by additional pre-job circulation to fully condition the wellbore.
The job was executed with no losses during cementing, and spacer and cement returns were received on the surface during reverse out. Utilizing the best engineering approach, practices, and techniques from this job is implemented in the future wells as the production of the well is directly affected by the cement quality. Post job cement integrity evaluation via a cement bond log confirmed excellent bonding of cement to the liner and reservoirs across the entire open-hole interval.
Solving Dual Casing Zonal Isolation with the Deployment of a New Well Abandonment System. Rock-to-Rock Barriers Sets for Major Operators
Authors: Khan Muhammad Zafar , Swadi Shantanu , Caminari Richard T , Burdett Timothy A , Stronach Graham 
Published: May 2021

Abstract
The Plug and Abandonment (P&A) requirement stipulates a permanent barrier to be placed for restoring the cap rock during well abandonment. For a single casing, section milling has been successfully implemented and widely used for a number of years. For a dual casing string, this becomes particularly challenging when both casing strings are cemented. Conventional techniques require milling the entire inner casing from the top of cement followed by section milling the outer casing. This could require milling up thousands of feet on of the inner string and is not a cost-efficient solution. The service company has been heavily involved in a number of P&A campaigns, where the requirement was to come up with a solution for dual casing section milling. This paper discusses the design, technology, field runs and best practices developed to overcome this operational and economic challenge and save rig time in P&A operations. The challenge was to design a robust section mill that can drift through the inner casing restriction and expand to a high ratio to mill the outer casing. It was equally critical to manage shock and vibrations during the milling operation, ensure stability and, competitive ROP without incurring tool damage.
To solve the operational and economic challenges, a unique system was developed to reduce the rig time. The system is a combination of the newly engineered high-ratio hydraulic section mill, with a 180% expansion ratio and a precisely oriented hydraulic stabilizer below it. This creates a unique 6-point stabilization system that helps to maintain the dynamic loads and vibrations to a manageable level. The system allows for a dual casing section window in few trips as compared to conventional techniques. In the first run, a window in the inner casing is milled by a section mill. During the second run, the High-Expansion Ratio Section Mill (HRSM) is run through the restriction, and mill the entire casing. A high ratio under reamer can be included in the bottom hole assembly to clean the section and expose the formation prior to the cementing operation. This completes achieving a rock-to-rock barrier in a dual cemented casing application.
The new HRSM system has so far been 100% successful on the five challenging jobs completed in Europe, Asia and the Middle East, resulted in significant rig-time savings along with the added benefits of fewer trips and less swarf at the surface.
Two sizes have been developed and tested for 7"x9-5/8" and 9-5/8"x13-3/8" applications. The success during the early jobs is largely due to the robustness of the mill design, proper pre-job planning, meticulous execution, and implementation of key learnings from in-house and prior field tests.
Conductor Sharing Drilling Technique
Authors: Alabbasy Emad Alabbasy , Ahmed Ahmed Khamis , Khaled Khalid Alwahedi , Abdulmohsen Abdulmohsen Al Marzooqi , Majid Majid Hammadi 
Published: May 2021

Abstract
With the objective to drill two wells shared from one conductor with independent wellhead and completion, ADNOC Offshore drilling team pioneered for the first time in Umm Lulu field and ADNOC UAE the Conductor sharing drilling technique. Which is to drill two wells from one single conductor in wellhead tower. Well planning technique drilling 42" hole and run 36" conductor, then install lower male connector and run conductor Down Hole Guide (DHG) assembly to be a guide for both two wells. Land the DHG on the lower male connector. Install upper male connector, which is equipped with two well slots for drilling the two wells. Drilling 1st 16" hole and run 13 3/8" casing and cemented. Skid over second slot and drill second hole 16" and run and cement 13 3/8" casing and carry out top up cement job for both hole up to surface inside 36" conductor. Install casing head housing for each well. Then each well could be drilled as per normal procedures.
Well executing process.
Well challenges:
Drilling large hole 42" hole with 42" bit and BHA.
Run 36" conductor and conductor sharing DHG and keep aligned for accessibility of BHA and casing Nudge 16" hole for both two wells at centre-to-centre distance 8" safely without collision issue.
Run two 13 3/8" casing strings in 36" conductor and cement same up to surface.
Complete drilling well UL-056 from slot A, drilled 12 ¼" hole section to TH-I ABS, run 9 5/8" casing and perform cement job to surface, drilled 6" hole (linerless design) and land in TH II then continued drilling horizontal drain to TD, Run completion and deliver the well. Suspend the other well in slot B at 13 3/8" casing with securing the well with abandonment cap and as per ADNOC offshore policy.
Evaluation of Cement-Casing & Cement-Rock Bond Integrity During Well Operations
Authors: Lamik Abdelfattah , Pittino Gerhard , Prohaska-Marchried Michael , Krishna Ravi , Thonhauser Gerhard , Antretter Thomas 
Published: May 2021

Abstract
This paper presents the results of laboratory static and dynamic tests on casing-cement-rock systems exposed to axial loads under ambient conditions. A new testing method has been developed.
The casing-cement-rock system mostly fails due to tension and shear stresses. In various applications such as HPHT, deep-water, (steam) injection or geothermal wells, the cement-casing bond is exposed to cyclic thermomechanical loads resulting in casing elongation, contraction, expansion and subsequently in cyclic radial and axial stresses at the cement-casing-rock system. Cement is a brittle material which can fail when subjected to repeated application of stresses lesser in magnitude than the statically determined strength. A novel atmospheric test cell has been designed and constructed. In order to achieve the fatigue limits of the cement-casing bond, a set of testing procedures has been established. Several tests are conducted to evaluate de-bonding. The focus on de-bonding is achieved by allowing the casing to move through the test while preventing any cement movement. Thus, when a force is applied in the axial z-direction - either the casing is pulled out (tension) or pushed down (compression) - the casing has enough space to move in both directions. The advantage of this testing method is that different stress ratios can be applied during the test.
Comparative Study of Managed Pressure Drilling Application in Deepwater Gas Wells - Case Study from Offshore Eastern Mediterranean of Egypt
Authors: El-Husseiny Mahmoud Ahmed , Khaled Samir Mohamed , El-Fakharany Taher El-Sebaay , Al-Nadi Yehia Mohamed 
Published: May 2021

Abstract
Although devised in 2003, managed pressure drilling (MPD) has gained widespread popularity in recent years to precisely control the annular pressure profile throughout the wellbore. Due to the relatively high cost and complexity of implementing MPD, some operators still face a challenge deciding whether or not to MPD the well.
In the offshore Mediterranean of Egypt, severe to catastrophic mud losses are encountered while conventionally drilling deepwater wells through cavernous fractured carbonate gas reservoirs with a narrow pore pressure-fracture gradient (PP-FG) window, leading to the risk of not reaching the planned target depth (TD). Furthermore, treating such losses was associated with long non-productive time (NPT), massive volume consumption of cement, and lost-circulation materials (LCM), in addition to well control situations encountered several times due to loss of hydrostatic head during severe losses. Accordingly, the operator decided to abandon the conventional drilling method and implement MPD technology to drill these problematic formations.
In this paper, the application of MPD is to be examined versus the conventional drilling in terms of well control events, NPT, rate of penetration (ROP), mud losses per drilled meter, LCM volume pumped, and drilling operations optimization.
According to the comparative study, MPD application showed a drastic improvement in all drilling performance aspects over the conventional drilling where the mud losses per drilled meter reduced from 19.6 m3/m to 3.7m3/m (123.2 bbl/m to 23.4 bbl/m). In addition to that, a 35% reduction of NPT and also a 35% reduction of LCM pumped, and 67.2 % reduction by volume of cement pumped to cure the mud losses. Moreover, the average mechanical rate of penetration increased by 37.4%. MPD was also credited with eliminating the need for an additional contingent 7" liner which was conventionally used to isolate the thief zone. The MPD ability to precisely control bottom hole pressure during drilling with the integration of MPD early kick detection system enables the rapid response in case of mud loss or kick, eliminating kick-loss cycles, well control events, and drilling flat time to change mud density.
This paper provides an advanced and in-depth study for deep-water drilling problems of a natural gas field in the East Mediterranean and presents a comprehensive analysis of the MPD application with a drilling performance assessment (average ROP, mud losses, LCM and cement volumes, well control events) emphasizing how MPD can offer a practical solution for future drilling of challenging deepwater gas wells.
Integrating the Fully Coupled Geomechanical with Thermodynamics Modeling for the Well Control in High Pressure and Temperature Condition
Authors: Wang Xindong , Ke Xue , Zhang Shuxia , Zhang Cheng , Li Hui , Li Pengfei , Li Zhenchuan , Huang Xingning 
Published: May 2021

Abstract
Drilling operations is risky due to narrow mud weight windows in deep wells. Different type of drilling events and wellbore instability have encountered frequently including inflow, drilling induced tensile fractures (DITF), losses and connection gas etc. As such to mitigate the problems, a robust pore pressure prediction is necessary with requires an understanding of the origins and distribution of overpressures in the area. The technical research process is divided into three steps: pre-drill pore pressure predication (PPP) modelling, real-time monitoring and post-drill validation. Efforts were made to understand the geological settings and temperature model. A pore pressure predication (PPP) model was built by integrating fully coupled geomechanical with thermodynamics modeling. Real-time monitoring information provides references and guidelines for PPP model optimization. During the post-drill stage, the updated PPP model was used to design a mud weight and casing program for the upcoming wells. The study area is located northwestern China, the deep formations that more than 7000 meters are ultra-high temperature (200-220 deg C). Thermal-related secondary pore pressure generating mechanism may become active leading to higher overpressure and difficulties in prediction. For the case study, an empirical relationship of overpressure impact factors versus temperature of sandstone and mudstone was proposed. An accurate PPP model is generated using available well-scale geomechanical model and overpressure impact factors. With an integrating fully coupled PPP model as foundation, the integrated approach helps to reduce serious wellbore instability caused by abnormal formation pressure, wellbore collapse and other complex drilling problems deep wells. A1 well was safely drilled guided by the study result and has no significant wellbore instability issues and has minimum reservoir damage due to optimal mud weight program. These findings will provide reference for overpressure mechanics study of deep wells. The multidisciplinary study results have created value by improving drilling performance and well delivery efficiency. It can also help operator reduce drilling costs and make development plan decisions.
Combining Machine Learning and Classic Drilling Theories to Improve Rate of Penetration Prediction
Authors: Zhang Hongbao , Lu Baoping , Liao Lulu , Bao Hongzhi , Wang Zhifa , Hou Xutian , Mulunjkar Amol , Jin Xin 
Published: May 2021

Abstract
Theoretically, rate of penetration (ROP) model is the basic to drilling parameters design, ROP improvement tools selection and drill time & cost estimation. Currently, ROP modelling is mainly conducted by two approaches: equation-based approach and machine learning approach, and machine learning performs better because of the capacity in high-dimensional and non-linear process modelling. However, in deep or deviated wells, the ROP prediction accuracy of machine learning is always unsatisfied mainly because the energy loss along the wellbore and drill string is non-negligible and it's difficult to consider the effect of wellbore geometry in machine learning models by pure data-driven methods. Therefore, it's necessary to develop robust ROP modelling method for different scenarios.
In the paper, the performance of several equation-based methods and machine learning methods are evaluated by data from 82 wells, the technical features and applicable scopes of different methods are analysed. A new machine learning based ROP modelling method suitable for different well path types was proposed. Integrated data processing pipeline was designed to dealing with data noises, data missing, and discrete variables. ROP effecting factors were analysed, including mechanical parameters, hydraulic parameters, bit characteristics, rock properties, wellbore geometry, etc. Several new features were created by classic drilling theories, such as downhole weight on bit (DWOB), hydraulic impact force, formation heterogeneity index, etc. to improve the efficiency of learning from data. A random forest model was trained by cross validation and hyperparameters optimization methods.
Field test results shows that the model could predict the ROP in different hole sections (vertical, deviated and horizontal) and different drilling modes (sliding and rotating drilling) and the average accuracy meets the requirement of well planning.
A novel data processing and feature engineering workflow was designed according the characteristics of ROP modelling in different well path types. An integrated data-driven ROP modelling and optimization software was developed, including functions of mechanical specific energy analysis, bit wear analysis and predict, 2D & 3D ROP sensitivity analysis, offset wells benchmark, ROP prediction, drilling parameters constraints analysis, cost per meter prediction, etc. and providing quantitative evidences for drilling parameters optimization, drilling tools selection and well time estimation.
Connexin 26 (GJB2) Gene Mutations Linked With Autosomal Recessive Nonsyndromic Sensorineural Hearing Loss in Iraqi Population.
Authors: Al-janabi Anwar Madlool , Ahmmed Habeeb Shuhaib , Alkhafaji Salih Mahdi 
Published: May 2021

Abstract
Objectives: The ARNSHL wasn’t been studied enough in Iraq, this study aimed to detect the prevalence of the three most common mutations of Connexin 26 gene in Iraqi population. This study was conducted in order to detect c.35delG, c.235delC and c.167delT mutations in GJB2 gene, we were employed PCR-RFLP assays.Results: The current case-control study was conducted from January 2018 to January 2020, The study was included 95 deaf patients (55 males and 40 females) their age range between 11-40 years and 21.5 ± 6.3 year (mean ± SD) and 110 healthy control group, their ages range between 10-40 years and 20.1 ± 5.9 year (mean ± SD), these two groups were matched in age and gender. From 95 deaf patients with ARNSHL who were participated in this study, c.35delG was the main frequent mutation encountered with GJB2 gene, The second frequent mutation was c.235delC, None of 95 deaf patients were showed the c.167delT mutation, these variants were not detected in healthy control group which was studied parallel with patients group. Our data conclude that GJB2 c.35delG and c.235delC gene mutations were the main cause of ARNSHL in Iraqi deaf population.
Chronic Foot Pain and Foot Solutions in Adults from Different Professions: the I-Corps-National Science Foundation Foot Health Survey.
Authors: Mbue Ngozi , Wang Wanyi , Rosario Martin 
Published: May 2021

Abstract
Background

Chronic foot pain (CFP) is a major contributor to sick leave and early retirement among individuals in all professions, especially those whose jobs require prolonged standing, lifting and walking. Current treatment modalities are inadequate in managing CFP. Hence, there is a significant need for new treatment options to manage chronic foot pain. The objectives of this study are i) explore the current state of chronic foot pain; ii) investigate current solutions and treatment options; and iii) explore opportunities for future inventions to address chronic foot pain.
Methods

Between April 2019 and September 2020, our team embarked on an I-Corps-National Science Foundation (NSF) programs in the United States to obtain information from stakeholders. Individualized, open-ended, mostly face-to-face interviews from nurses, athletes, construction and restaurant workers, among others were conducted.
Results

Preliminary data (N = 119) showed that current solutions and treatments for CFP were insufficient in managing moderate to acute pain (mostly pain scale 5 on a scale of 0–10). Those with ≥ 5 pain, changed shoes (63.3%), used shoe inserts, nursing clogs and painkillers (53.3%), and compression stockings (40%), with none reporting effectiveness. Fisher's exact tests were used to examine the relationships between regions (foot, heel and leg) and pain solutions. Regions (foot and heel) and shoe change were significantly related (p = 0.006) with participants using 5–7 pairs of shoes interchangeably, spending approximately $500-$700/year on new shoes. Female nurses 30–40 years experienced the highest foot pain than those younger. No significant differences in nursing and other professions with regards to CFP and solutions.
Conclusions

The majority expressed interest in trying new products to relieve their chronic foot and heel pain. Risk factors for foot pain included prolonged standing, walking, and lifting heavy objects. Current solutions are inadequate for managing moderate to acute foot pain in those who stand for prolonged periods of time on their feet. Innovations are urgently needed to address CFP.
Cerebellar White Matter Abnormalities in Patients with Charcot-Marie-Tooth disease
Authors: Kim Hyeon-Jin , Park Chang-Hyun , Kim Regina Eun-Young , Hwang Sungeun , Choi Yun Seo , Kim Sol-Ah , Yoo Jeong Hyun , Chung Ki Wha , Choi Byung-Ok , Lee Hyang Woon 
Published: May 2021

Abstract
Charcot-Marie-Tooth disease (CMT) is a genetically heterogeneous hereditary peripheral neuropathy. Brain volumetry and diffusion tensor imaging (DTI) were performed in CMT patients with PMP22 duplication, MFN2, GJB1, or NEFL mutations to investigate for structural changes of the cerebellum.Volume in cerebellar white matter (WM) was significantly reduced in CMT patients with NEFL mutations. Abnormal DTI findings ​​were observed in the superior, middle, and inferior cerebellar peduncles predominantly in NEFL mutations, and partly in GJB1 mutations. Cerebellar ataxia was more prevalent in the NEFL mutation (72.7%) than GJB1 mutation (9.1%), but not observed in other genotypic subtypes, which indicates that structural cerebellar abnormalities were associated with the presence of cerebellar ataxia. However, NEFL and GJB1 mutations did not affect cerebellar gray matter (GM), and neither cerebellar GM nor WM abnormalities were observed in PMP22 duplication or MFN2 mutations. We found structural evidence of cerebellar WM abnormalities in CMT patients with NEFL and GJB1 mutations and the association between cerebellar WM involvement and cerebellar ataxia in these genetic subtypes, especially in the NEFL subgroup. Therefore, we suggest that neuroimaging such as MRI volumetry or DTI in CMT patients could play an important role in detecting abnormalities of the cerebellar WM.