bluuebunny/crossref_metadata_2025_split huggingface dataset:
High Frequency Pressure Monitoring of the Re-Fracturing or Continuous Pumping Operations: Case Studies
Authors: Estrada Juan David , Korkin Roman , Parkhonyuk Sergey 
Published: January 2022

Abstract
The opportunity to refracture low-producing horizontal wells, which have been fractured few months before is getting more and more popular in the last few years. It provides the opportunity of restoring production without drilling new wells, which might be economically feasible especially in the oil and gas low price environment. However, the success rate of refracturing operations is usually low, mainly driven by the inability to properly stimulate the entire horizontal section. Consequently, many operators do not widely deploy this efficient technology. In contrast, completing a newly drilled well with plug and perf technology allows to individually treat from forty to sixty or even more individual compartments in the lateral section while refracturing attempts to retreat the entire lateral in the absence of any isolating device while trying to cover the entire lateral.
There are at least two key factors affecting this operation. First is diversion technology: without efficient chemical diverters, which allow to temporarily block recently treated intervals and divert the stimulation fluid to different open sections of the well is extremely challenging. These diverters should normally be able to hold pressure differentials up to thousand psi or more. Attempting a treatment without this technology, aka a "blind frac" is not an option in many cases. The second factor is monitoring technology: The ability to recognize whether a zone has been successfully stimulated, to decide on the deployment of diverting technology or the further addition of stimulation fluid, to sponsor lateral coverage with minimal risk of premature screen out becomes of utmost importance for the successful outcome of hydraulic refracturing operations. In the absence of either of the aforementioned factors hydraulic refracturing may become inefficient and yield uneconomic success.
This paper presents how the application of novel diverters, combined with proper hydraulic fracturing fluid selection, sound engineering design and more importantly hydraulic fracturing monitoring provide a new opportunity for the deployment of hydraulic refracturing to provide significant production increase and enhance recovery factor.
Enhancements in Fracturing Fluid Engineering Reawakens a North Sea Giant
Authors: Hoq Asif , Caline Yann , Jakobsen Erik , Wood Neil , Stolpman Rob , Thirion Aurelien , Giffin Wade 
Published: January 2022

Abstract
The Valhall field, operated by AkerBP, has been a major hub in the North Sea, on stream for thirty-eight years and recently passed one billion barrels of oil produced. The field requires stimulation for economical production. Mechanically strong formations are acid stimulated, while weaker formations require large tip-screenout design proppant fractures. Fracture deployment methods on Valhall have remained relatively unchanged since the nineties and are currently referred to as "conventional". Those consist in a sequence of placing a proppant frac, cleaning out the well with coiled tubing, opening a sleeve or shooting perforations, then coil pulling out of hole pumping the proppant frac. For the past few years, AkerBP and their service partners have worked on qualifying an adapted version of the annular coiled tubing fracturing practice for the offshore infrastructure - a first for the industry, which has been a strategic priority for the operator as it significantly reduces execution time and accelerates production.
As with all technology trials, the implementation of this practice on Valhall had to begin on a learning curve through various forms of challenges. Whilst investigating the cause and frequency of premature screenouts during the initial implementation of annular fracturing, the team decided to challenge the conventional standards for fluid testing and quality control. Carefully engineered adjustments were made with regards to high shear testing conditions, temperature modelling, and mixing sequences, these did not only identify the root cause for the unexpected screenouts, but also helped create the current blueprint for engineering a robust fluid.
Since the deployment of the redefined recipe, adjusted testing procedures and changes made to the stimulation vessel, there have not been any cases of fluid induced screenouts during the executions. The fewer types of additives now required for the recipe have lowered the cost of treatments and the lower gel loading leads to reduced damage in the fractures, thereby contributing to enhanced production over the lifetime of the wells.
This paper describes the investigation, findings and the resulting changes made to the fluid formulation and quality control procedures to accommodate for high shear and dynamic wellbore temperature conditions. It discusses the rationale behind the "reality" testing model and, proves that significant value is created from investing time in thoroughly understanding fluid behaviour in the lab, prior to pumping it on large-scale capital-intensive operations. The study demonstrated that there is always value in innovating or challenging pre-conceived practices, and the learnings from this investigation significantly improved the track record for annular fracturing on Valhall, redefined fluid engineering for the North Sea and will inform future annular fracturing deployments on other offshore assets around the world.
From Technical Evolution to Production Performance: A Technical Review of 700 Wells Over 8 Years in the South Sulige Tight Gas Field
Authors: Wang Dong , Dong Yifan , Yang Shengfang , Rignol Joel , Wang Qiang , Liu Yuan , Liu Yaolan , Zhao Liang , Wang Weikan , Loh Pengpeng , Enkababian Philippe 
Published: January 2022

Abstract
Unlike many unconventional resources that demonstrate a high level of heterogeneity, conventional tight gas formations often perform consistently according to reservoir quality and the applied completion technology. Technical review over a long period may reveal the proper correlation between reservoir quality, completion technology, and well performance. For many parts of the world where conventional tight gas resources still dominate, the learnings from a review can be adapted to improve the performance of reservoirs with similar features.
South Sulige Operating Company (SSOC), a joint venture between PetroChina and Total, has been operating in the Ordos basin for tight gas since 2011. The reservoir is known to have low porosity, low permeability, and low reservoir pressure, and requires multistage completion and fracturing to achieve economic production.
Over the last 8 years, there has been a clear technical evolution in South Sulige field, as a better understanding of the reservoir, improvement of the completion deployment, optimized fracturing design, and upgraded flowback strategy have led to the continuous improvement of results in this field. Pad drilling of deviated boreholes, multistage completions with sliding sleeve systems, hybrid gel-fracturing, and immediate flowback practices, gradually proved to be the most effective way to deliver the reservoir's potential.
Using the absolute open-flow (AOF) during testing phase for comparative assessment from South Sulige field, we can see that in 2012 this number was 126 thousand std m3/d in 2012, and by 2018 this number had increased to 304 thousand std m3/d, representing a 143% incremental increase. Thus, technical evolution has been proved to bring production improvement over time. Currently, South Sulige field not only outperforms offset blocks but also remains the top performer among the fields in the Ordos basin. The drilling and completion practices from SSOC may be well suited to similar reservoirs and fields in the future.
A New Laboratory Technique to Enhance Proppant Consolidation During Propped Hydraulic Fracturing Treatment
Authors: Alqam Mohammad Hassan , Al-Makrami Adnan Hussain , Abass Hazim Hussain 
Published: January 2022

AbstractThe objectives of this investigation were to perform a rock mechanical study to evaluate long term stability of Resin-Coated Proppant (RCP), combined with various additives currently being used in screenless propped hydraulic fracturing completions in the sandstone formations. Thereby providing a tool for the industry to know exactly the duration of the shut-in time before putting a well back onto production.A new experimental method was developed to monitor the curing process of RCP as temperature increases. The velocity of both shear and compressional waves were being monitored as a function of temperature, while the tested RCP sample was being housed in a pressurized vessel. The pressurized vessel was subjected to a variable temperature profile to mimic the recovery of the reservoir temperature following a propped hydraulic fracturing treatment. The placed proppant should attain an optimum consolidation to minimize the potential for proppant flow back. The study has been performed on various types of RCP samples under a range of reservoir conditions. The role of closure stress, temperature, curing time and carrier fluids in attaining a maximum strength of RCP following a propped hydraulic fracturing treatment have been investigated. Also, the Unconfined Compressive Strength (UCS) of various types of RCP have been measured.The testing methods currently practiced in the industry to qualify proppant for field applications are based on physical characterization of several parameters such as the specific gravity of proppant, absolute volume, solubility, roundness, sphericity and bulk density. The sieve analysis, compressive strength, and API crush testing are also measured and reported. The API Recommended Practices; API RP56, API RP58 and API RP60 are the main procedures used to test the suitability of proppants for hydraulic fracturing treatment. However, there is no published API testing method for RCP; therefore this study introduces a new testing procedure, using acoustic velocity as a function of temperature and compressive strength as a function of time; to qualify a given RCP for a particular reservoir of known stress and temperature.The final outcome of this study is to establish a functional procedure for such measurements, in order to maximize the success of a propped hydraulic fracturing treatment and minimize the occurrence of flow back incidents.
Controlled Frac Height Growth Technique to Avoid Contacting Water-Bearing Layer
Authors: Al-Obaid Hashem , Asel Sultan A. , Hansen Jon , Wijaya Rio 
Published: January 2022

Abstract
Many techniques have been used to model, diagnose and detect fracture dimension and propagation during hydraulic fracturing. Diagnosing fracture dimension growth vs time is of paramount importance to reach the desired geometry to maximize hydrocarbon production potential and prevent contacting undesired fluid zones. The study presented here describes a technique implemented to control vertical fracture growth in a tight sandstone formation being stimulated near a water zone. This gas well was completed vertically as openhole with Multi- Stage Fracturing (MSF).
Pre-Fracturing diagnostic tests in combination with high-resolution temperature logs provided evidence of vertical fracture height growth downward toward water zone. Pre-fracturing flowback indicated water presence that was confirmed by lab test. Several actions were taken to mitigate fracture vertical growth during the placement of main treatment. An artificial barrier with proppant was placed in the lower zone of the reservoir before main fracturing execution. The rate and viscosity of fracturing fluids were also adjusted to control the net pressure aiming to enhance fracture length into the reservoir.
The redesigned proppant fracturing job was placed into the formation as planned. Production results showed the effectiveness of the artificial lower barrier placed to prevent fracture vertical growth down into the water zone. Noise log consists of Sonic Noise Log (SNL) and High Precision Temperature (HPT) was performed. The log analysis indicated that two major fractures were initiated away from water-bearing zone with minimum water production. Additionally, in- situ minimum stress profile indicated no enough contrast between layers to help confine fracture into the targeted reservoir. Commercial gas production was achieved after applying this stimulation technique while keeping water production rate controlled within the desired range.
The approach described in this paper to optimize gas production in tight formation with nearby water contact during hydraulic fracturing treatments has been applied with a significant improvement in well production. This will serve as reference for future intervention under same challenging completion conditions.
A State-of-the-Art Approach to Unlock the Potential of Complex Sour Reservoirs in Southern Oman During Global Market Downturn
Authors: Sayapov Ernest , Molenaar Mathieu , Nunez Alvaro , Benchekor Ahmed , Hadhrami Abdullah , Smirnov Dmitry , Amin Khalil Mohamed , Ainouche Dalil 
Published: January 2022

Abstract
Recent years and especially the coronavirus pandemic have been very challenging for the oil industry, resulting in a significant reduction in investment, forcing companies to review budgets and search for more efficient and economical technologies to achieve the target level of hydrocarbon production and revenue generation.
In PDO, one of the most challenging fields is "AS", where extreme downhole conditions require a very well-engineered approach to become economical. This field has already seen some of the most advanced technology trials in PDO that are also covered in multiple SPE papers. Based on the new approaches and techniques that were successfully implemented on recently drilled wells, it was decided to review the older, previously fractured wells in the area and assess them for a refracturing opportunity.
The main challenge in this project was that these older wells were previously hydraulically fractured in multiple target intervals, therefore both zonal isolation and successful placement of the new fracs were becoming the major concerns. As the planned coverage by the new fractures was to ensure no bypassed pay, the only applicable technology on the market was a pinpoint fracturing process, whereby the targeted placement is achieved through limited entry perforations and focused energy of the injected fluid.
The subject pinpoint technology anticipates that the limited entry sandblasting perforation is created and then proppant laden fluid is pumped through a sandblasting nozzle which is part of either a coiled tubing (CT) or a jointed pipe (JP) Bottom Hole Assembly (BHA), and the backside (or the annulus of the injection path) is used to maintain the positive backpressure from the top. This technology allows for choosing a desirable order of target interval selection inside the well, unlike conventional plug and perf or a simplified multistage completion, where the treatments must be placed only in order from bottom to top. Another advantage of this approach is a faster frac cycle through the elimination of wellbore cleanout requirement.
Being a unique and first-ever application in the Middle East, using CT for placing frac treatments through a jetting nozzle demonstrates the full scale potential of this approach not only in conventional wells but also in complex, sour and High Pressure (HP) environments that are often found in the Sultanate of Oman and in the Middle East. This paper will cover the advantages and disadvantages, complexity and requirements, opportunities and lessons learnt in relation to this approach.
Power Maximization in Standalone Photovoltaic System: An Adaptive PSO Approach
Authors: MP Anbarasi , S Kanthalakshmi 
Published: January 2022

Abstract
A control strategy for power maximization which is an important mechanism to extract maximum power under changing environmental conditions using Adaptive Particle Swarm Optimization (APSO) is proposed in this paper. An Adaptive Inertia Weighting Factor (AIWF) is utilised in the velocity update equation of traditional PSO for the improvement in speed of convergence and precision in tracking Maximum Power Point (MPP) in standalone Photovoltaic system. Adaptation of weights based on the success rate of particles towards maximum power extraction is the most promising feature of AIWF. The inertia weight is kept constant in traditional PSO for the complete duration of optimization process. The MPPT in PV system poses a dynamic optimization problem and the proposed APSO approach paves way not only to track MPP under uniform irradiation conditions, but also to track MPP under non uniform irradiation conditions. Simulations are done in MATLAB/Simulink environment to verify the effectiveness of proposed technique in comparison with the existing PSO technique. With change in irradiation and temperature, the APSO technique is found to provide better results in terms of tracking speed and efficiency. Hardware utilizing dSPACE DS1104 controller board is developed in the laboratory to verify the effectiveness of APSO method in real time.
The Effects of Breathing Exercises and Inhaler Training in Patients with COPD on the Severity of Dyspnea and Life Quality: A Randomized Controlled Trial
Authors: CEYHAN YASEMİN , KARTIN PINAR TEKİNSOY 
Published: January 2022

Abstract
Background: Severe dyspnea and poor quality of life are common in chronic obstructive pulmonary disease (COPD). The most important reason for this situation is the wrong applications in inhaler treatment. In addition, inhaler treatments that supporting non-pharmacological methods increases the effectiveness of the drug. The aim of this study is to determine the effects of breathing exercises and inhaler training for chronic obstructive pulmonary disease patients on the severity of dyspnea and life quality.Methods: The research is a randomized controlled trial. A total of 67 with COPD who complied. The patients who were randomized in two groups that Intervention 1 group were given pursed lip breathing exercise and inhaler training and Intervention 2 group were given only inhaler training. A follow-up after 4 weeks was carried out in both groups. Patient outcomes in both groups were COPD assessment test (CAT), Modified medical research council (mMRC), and St. George's respiratory questionnaire scales (SGRQ). This study followed CONSORT checklist for randomized conrolled trials. In data analysis independent t, Mann-Whitney U, ANOVA, Wilcoxon analysis, and Pearson Chi-square tests were used.Results: Pursed lips exercise and inhaler drug use skills of patients in the both group increased (p<0.001). The median value of the CAT and mMRC scores are is statistically significant for both groups (p<0.005). The mean of life quality scores of patients in both groups decreased and this result was found statistically significant in all sub-dimensions and in the total scale score for two groups (p<0.001). Although the increase in the quality of life and the decrease in the severity of dyspnea of the patients in both groups were significant, the two groups were not superior to each other (p>0.05).Conclusions: As a result of the study, it was found that the skill of applying inhaler and life quality of the patients increased, the severity of dyspnea decreased. Supporting inhaler treatments with non-pharmacological methods can increase drug efficacy and quality of life. Trial Registration: Clinical Trial Registry registration number: NCT04739488. Registered on 21 Feb 2021.
Predictive Value of the PaO2/FIO2 Ratio for Mortality in Patients with Acute Respiratory Distress Syndrome: A Systematic Review and Meta-Analysis
Authors: Yoshimura Satoshi , Hashimoto Katsuhiko , Shono Yuji , Tamura Takahiro , Uchimido Ryo , Ando Koichi , Okamori Satoshi , Yoshida Takuo , Yoshitake Shigenori , Okada Yohei 
Published: January 2022

Abstract
Background PaO2 /FIO2 (P/F) ratio has been used to define the severity of acute respiratory distress syndrome (ARDS) despite the controversy of its clinical utility. This systematic review and meta-analysis (SRMA) aimed to obtain summary estimates of predictive performance of the P/F ratio for predicting mortality in ARDS patients. Methods We included a study wherein the study population comprised ARDS patients in any clinical setting. Medline and Cochrane Central Registry of Controlled Trials were searched for all English language articles. We performed a SRMA on the accuracy of diagnostic prognostic tests using QUADAS-2 tool to evaluate the risk of bias. To pool the results, we applied the bivariate model and obtained summary point estimates of sensitivity and specificity with 95% CIs. Results Twenty-eight trials and 38270 patients were included in the meta-analysis. Most of the study settings were in the intensive care units. The overall risk of bias was high. The pooled sensitivity of the P/F ratio in all included studies for a P/F ratio of 100 was 43.6% (95% CI, 36.9-50.5%) and the specificity was 71.1% (95% CI, 66.7-75.1%) and those for a P/F ratio of 200 were 83.2% (95% CI, 78.2-87.2%) and 26.2% (95% CI, 21.2-31.9%). Interpretation The P/F ratio had high sensitivity and moderate specificity at a P/F ratio of 200 and 100 respectively, which supports the use of the P/F ratio for screening ARDS patients who are at risk of deterioration.Trial registration: The study was registered in UMIN with registration number 64 000041058.
A Hybrid Space-Time Modelling Approach for Forecasting Monthly Temperature
Authors: KUMAR RAVI RANJAN , Sarkar Kader Ali , Dhakre Digvijay Singh , Bhattacharya Debasis 
Published: January 2022

Abstract
Spatio-temporal forecasting has various applications in climate, transportation, geo-statistics, sociology, economics and in many other fields of study. The modelling of temperature and it forecasting is a challenging task due to spatial dependency of time series data and nonlinear in nature. To address these challenges, in this study we proposed hybrid Space-Time Autoregressive Moving Average-Generalized Autoregressive Conditional Heteroscadicity (STARMA-GARCH) model in order to describe and identify the behaviour of monthly maximum temperature and temperature range in Bihar. At the modelling process of STARMA, spatial characteristics are incorporated into the model using a weight matrix based on great circle distance between the regions. The residuals from the fitted STARMA model have been tested by Brock, Dechert, and Scheinkman (BDS) and Autoregressive Conditional Heteroscadicity-Lagrange Multiplier (ARCH-LM) test for the behaviour of nonlinearity and ARCH effect respectively. The test results revealed that presence of both nonlinearity and ARCH effect. Hence GARCH modelling is necessary. Therefore, the hybrid STARMA-GARCH model is used to capture the dynamics of monthly maximum temperature and temperature range. The results of the proposed hybrid STARMA (1 1 , 0, 0)−GARCH (0, 1) model has better modelling efficiency and forecasting precision over STARMA (1 1 ,0, 0) model.