bluuebunny/crossref_metadata_2025 huggingface dataset:
Компактная аппроксимация двумерной краевой задачи для эллиптических уравнений второго порядка с разрывным коэффициентом
Authors: Гордин Владимир Александрович , Gordin Vladimir Aleksandrovich , Шадрин Д А , Shadrin D A
Published: March 2023

Для эллиптического уравнения 2-го порядка с переменными разрывными коэффициентом и правой частью построена схема 4-го порядка точности. На линии скачка предполагаются выполненными условия стыковки (Кирхгофа). Применение экстраполяции Ричардсона, как показали численные эксперименты, увеличивает порядок точности примерно до 6-го. Показано, что релаксационные методы, в том числе многосеточный, применимы для решения таких систем линейных алгебраических уравнений (СЛАУ), отвечающих компактной конечно-разностной аппроксимации задачи. По сравнению с классической аппроксимацией точность увеличивается примерно в 100 раз при той же трудоемкости. Рассмотрены различные варианты уравнения и граничных условий, а также задача на определение собственных чисел и функций для кусочно-постоянного коэффициента уравнения.
Factors Associated with Self-reported Memory Problems of Adult Cancer Survivors Based on the Korea National Health and Nutrition Examination Survey 2019
Authors: Ko Sangjin
Published: March 2023

Objectives: With the development of treatment technology, the percentage of cancer survivors has continued to increase. However, the cognitive decline these patients experience has been overlooked because it is not related to survival. This study investigated factors related to memory problems in patients with cancer.Methods: Using data from the 2019 Korea National Health and Nutrition Examination Survey (KNHANES), this secondary data analysis study attempted to identify factors related to memory problems in cancer survivors. Of the 8,110 survey participants, there were 6,296 adults, aged 19 years or older. Of these, 357 were diagnosed with cancer. Four participants were excluded due to missing values for occupation, income, and body mass index (BMI). Finally, 353 subjects were included in the research analysis. The data were statistically analyzed using IBM SPSS version 28.0.Results: 218 (61.8%) of the cancer survivors reported memory problems. Having a lower-than-average individual income (odds ratio, OR = 2.16, 95% confidence interval, CI = 1.31-3.53, p= 0.003), smoking (OR = 3.19, 95% CI = 1.16-8.72, p= 0.024), and depression (OR = 6.06, 95% CI = 1.33-27.57, p= 0.020) were significant potentiating factors. In contrast, having a job (OR = 0.18, 95% CI = 0.05-0.67, p= 0.011), drinking (OR = 0.26, 95% CI = 0.09-0.81, p= 0.021), and walking three to four days per week (OR = 0.15, 95% CI = 0.03-0.81, p= 0.027) decreased memory problems.Conclusions: Our findings suggest that it is necessary to develop cognitive rehabilitation programs for cancer survivors.
Rohr and Benz, Queenship and the Women of Westeros. Female Agency and Advice in Game of Thrones and A Song of Ice and Fire (Palgrave MacMillan, 2020)
Authors: Storey Gabrielle
Published: March 2023

Review of Zita Eva Rohr and Liza Benz, Queenship and the Women of Westeros. Female Agency and Advice in Game of Thrones and A Song of Ice and Fire (Cham: Palgrave MacMillan, 2020).
Some Candidates for the Vacant Throne of Interwar Hungary: International Approaches to Finding a Resolution
Authors: Kerepeszki Róbert
Published: March 2023

After the resignation of Charles IV, a particular public law situation, the so-called “kingdom without a king,” came about in interwar Hungary, which persisted through the whole period. The “king question” that developed around taking the vacant throne aroused a keen interest not only in internal politics, but also abroad. The study gives a short account about who could emerge as a possible Hungarian king and why they could do so, and how the issue was presented to the international public. The author analyses the rumours, both in the press and in diplomatic documents, which are rather under-exploited as sources in historical research. The article first outlines the general socio-political situation in post-Great War Hungary and then shows how the problem of the “king question” divided Hungarian public life into several camps. It then, without claiming completeness, examines the motivations and realities of combinations for some of the individuals who most frequently appeared as candidates for king in the various rumours. In terms of the timing of the rumours, the study highlights the domestic and international events and circumstances in which interest in the issue of Hungary’s “kingless kingdom” was heightened in public discourse, and how such combinations influenced the image of contemporary Hungary. It also sheds light on the reasons that have prevented the kingdom issue from being settled. Finally, the author attempts to outline what the “ideal” new Hungarian king, acceptable both abroad and at home, should have been like under the given circumstances.
Murray, Baldwin of Bourcq: Count of Edessa and King of Jerusalem (1100-1131), (Routledge, 2021)
Authors: Donnachie Stephen
Published: March 2023

Review of Alan V. Murray, Baldwin of Bourcq: Count of Edessa and King of Jerusalem (1100-1131), (New York: Routledge, 2021).
Schroder, ‘A Marvel to Behold’: Gold and Silver at the Court of Henry VIII, (The Boydell Press, 2020)
Authors: Hayward Maria
Published: March 2023

Review of Timothy Schroder, ‘A Marvel to Behold’: Gold and Silver at the Court of Henry VIII (Woodbridge: The Boydell Press, 2020).
Botsman and Clulow, Commemorating Meiji: History, Politics and the Politics of History (Routledge, 2022)
Authors: Miller Alison J
Published: March 2023

Review of Botsman and Clulow, Commemorating Meiji: History, Politics and the Politics of History (Routledge, 2022)
Religious Psychosocial Healing for the Trauma of the Children of the Terrorists
Authors: Miftahuddin Miftahuddin , Triyoko Hanung , Habibi Burhan Yusuf , Iqdami Muhammad Nazil
Published: March 2023

This study aims to reveal the trauma-healing process with a religious psychosocial approach to the children of the terrorists. Qualitative method is used to describe the trauma healing process analytically. The subjects in this study were 10 children of perpetrators of acts of terrorism in Surabaya, Magetan, Banten, and Bogor, who were cared for at the Islamic Boarding School, the Central Java Fostering House, Indonesia. Data collection techniques include in-depth interviews, observation, and documentation. This study found that the children of the terrorists have traumas in the form of feelings of excessive threat, remembering repeated and continuous events, and feeling helpless. To get rid of this trauma, the Central Java Islamic Boarding School conducted trauma healing with a religious psychosocial approach through three phases. First, creating a sense of security and stabilizing emotions. Second, training the children to make peace with the trigger of the trauma. Third, training the children to naturally socialize with the pesantren, school, and community environment. The novelty of this research lies in the integration of psychological, social, and religious approaches in trauma healing. The implication of this research is to enrich the trauma-healing model of the children of the terrorists.
Portrait of Indonesian Religious Communities Attitudes toward the Government Policies Restriction on Congregational Worshipping
Authors: Sardjuningsih Sardjuningsih
Published: March 2023

Many offenses have been perpetrated by Indonesian religious communities toward the government’s policies on the restriction of congregational worshipping during the COVID-19 pandemic. However, scant studies investigating those negative attitudes using a qualitative approach. In order to fill the gap, this paper reports on the religious attitudes of Muslims who are considered to violate the restriction policy on religious activities ordered by the Indonesian government. The involved participants were policymakers, mosque caretakers, and the three largest Muslim social groups, including Muhammadiyah, Nahdlatul Ulema (NU), and traditionalists. The results of this study revealed discrepancies in how Muslims' polarized religious attitudes are constructed. These communities have different patterns of thought and diversity in terms of perceiving the government’s policies.  This study suggests that there is a critical role for Islamic scholars in educating Muslims about the dangers and possible consequences of COVID-19. In other words, following government policies while partaking in congregational worship can be interpreted as a manifestation of social piety, spiritual activity, and religious faith.
Wettability Alteration with Weak Acid-Assisted Surfactant Flood
Authors: Shi Yue , Niu Fangya , Mohanty Kishore
Published: March 2023

Oil-wetness and heterogeneity are two key reasons for low oil recovery by waterflooding in carbonate reservoirs. Surfactants have been effective in altering the oil-wet matrix to a more water-wet condition and initiating spontaneous imbibition. Because it takes time for the surfactant to alter wettability, oil recovery from the tight matrix is slow and sometimes not economically feasible. Acids have the potential of dissolving minerals, which may alter wettability. In this study, the enhanced oil recovery (EOR) performance of an acid-assisted surfactant solution, a novel technique, was evaluated for low-temperature applications. A set of acids and their acetates were tested. Bulk rock-acid reaction, wettability alteration (WA) tests, and spontaneous imbibition measurements were conducted at reservoir temperature (35°C) to identify effective candidates. Coreflood tests were then performed to evaluate the selected acid-surfactant formulations. Before and after a coreflood test, the core was scanned using micro-computed tomography (CT) to investigate pore structure alteration. Bulk reaction measurements showed that weak acids, especially acetic acid (AA), have the desired low reaction rates at 35°C. WA tests showed that AA can remove the crude oil off the rock surface and alter wettability through mineral dissolution. The surfactant can reduce contact angles from 160° to 58°; adding acid into the surfactant can further reduce it to 52°. Spontaneous imbibition experiments showed the synergy between the acid and the surfactant; the AA-surfactant solution had the highest oil recovery (62.6%) among acid-surfactant formulations. The acid improves the WA efficiency by the surfactant through surface mineral dissolution and lower ζ-potential. The imbibition transports the acid-surfactant solutions into the matrix, which minimizes face dissolution. Coreflood tests show that the AA-surfactant flood can increase the oil recovery rate and recover about 8% more oil compared to the surfactant flood. Micro-CT showed that a few mineral particles were transported along the core and partially plugged pore throats, which reduced permeability and diverted flow leading to improved oil recovery. The transport of the acid in reservoirs and the potential plugging issues have to be carefully evaluated in future studies.
Integrated Velocity Modeling by Water Table Imaging and Structural Smoothing in Yingxiongling, Qaidam Basin
Authors: Tan Chenqing , Wang Yongsheng , Tong Yanming , Ou Rongsheng , Wu Chuan , Yan Yufei , Zhao Changlei , Li Xiang , Cui Jie , Dong Yongcang , Li Rong
Published: March 2023

The Yingxiongling structural belt is located in the south of world's highest-altitude petroliferous basin, Qaidam Basin. It is well known for the extremely complicated topography and subsurface structure. Accurate velocity modeling and depth imaging is extremely difficult, as well as exploration and production in this area. Building a reliable initial model that accounts for both near-surface and subsurface structures is crucial. We first generate a geologically-guided subsurface velocity model by structural smoothing of the pre-stack time migration (PSTM) velocity guided by dip field. Furthermore, we take the water table, a typical geological phenomenon in Qaidam basin, into account for near surface modeling. With information regarding a stable and smooth water table, we achieve an optimum image predicting the trap, thus supporting exploration and production in the area.
True Single-Trip Wellbore Cleanout: Optimizations in Cemented Liner and Multi-Stage Frac Completions
Authors: Franco Nata , Cardoso Luiz Miguel , Corona Mauricio
Published: March 2023

Depending on the production requirements, the deep gas wells in the field were completed with cemented liner or multi-stage frac equipment. Following installation of lower completion, these wells historically required 3 to 4 wellbore cleanout runs prior to deployment of upper completion equipment. This paper will describe the optimizations done to convert all the cleanout runs, into a true single-trip job, reducing the total well construction by introducing groundbreaking technology and fit-for-purpose operations.

The standard procedure wellbore cleanout involved 3 to 4 trips: Firstly, cement cleaning was done inside the 4-1/2″ liner, including drill-out of shoe-track, followed by scraping of 7″ liner for running test packer tool; then run and setting of packer to perform casing and top of liner pressure tests; next perform full cleanout of casings, pickle production casings and displacing well to brine, and finally polish 4-1/2″ liner tie-back receptacle to receive upper completion assembly in cemented applications. Detailed engineering analysis, risk assessment and market research were conducted to develop an optimized wellbore cleanout assembly, to perform single-trip jobs.

The conventional cleanout package was upgraded with modified scrapers, magnets, and brushes, and combined with specialized high-pressure test packer and polish mill. Modification in equipment and procedures evolved following results and observations of several runs of the combined technology. The drilling and completion fluids were also re-engineered to ensure proper cleaning of casing and free-solids wellbore. The final results were an extreme success and single-trip wellbore cleanout became the new norm in the project. The innovate approach greatly contributed to reducing the number of runs to prepare the wellbore for upper completions.

Operations have been conducted safely throughout its implementation and kept at low non-productive rate. In average, the reduction of total well time was 3.5 days with relatively marginal tool rental cost increment. This optimization was a breakthrough in the Middle East with major rig time savings and it will serve as a reference for other operators and service providers to achieve step changes in similar operations. The key elements of this initiative will be described in detail in the paper.
Gas Lift Application for Oil Wells with Heavy Crude, Thirty Years of Operation Offshore Gulf of Suez
Authors: Korish Mahmoud Ismail , Elwan Mahmoud Attia , Mousa Hisham Elsaied , Shahin Eman Said , Ibrahim Mohamed Elsayed
Published: March 2023

This paper presents the implications of Gas lift over the heavy oil fields, since Gas Lift is considered one of the oldest artificial lift techniques in Oil industry. Despite the numerous publications about different aspects of gas lift, few of them is meant to deeply consider the applicability of gas lift to heavy oil production. Gas Lift has been applied to heavy oil in different places around the world. For Gas lift has been used in Gulf of Suez in Egypt historically to produce Heavy Oil Reservoir with 17 – 19.5 API.

The major challenge for application of Gas lift in heavy oil application is the typical low GOR encountered in Heavy oil fluid properties. The low GOR may not be suitable for gas supply to compressors, which requires gas availability to avoid tripping due to low suction or overheating during startup operations. However, in many cases nearby gas wells has been used as gas supply to compression equipment used for gas lift.
Elevating Drilling Performance & Efficiency to Highest Levels in Field A – Journey from 150 to 31 Drilling Days
Authors: Ullah Safi , Ashraf Muhammad Sajjad , Ahmed Ali Mohiuddin , Ahmad Daniyal , Haider Mohammad Murad , Usmani Mohammad Mohsin , Ali Syed Dost
Published: March 2023

Field A is one of the most challenging fields in the Potowar region of Northern Pakistan with severe problems of fluid loss, high-pressure shallow water influx, low drillability, clay reactivity/ shale instability and depleted reservoir sections. This paper gives a brief overview of the methods and changes made along with results achieved, enabling the well to reach total depth in just 31 days compared to an average of 150 days taken on offset wells.

Due to severe drilling challenges, the wells were drilled in six-hole sections starting with 36″ surface hole. An entirely new well engineering strategy has been utilized to enhance the drilling performance in the last five wells drilled in the field. Some of the major areas of change include Customized bit design, BHA and hydraulics design, casing design optimization and change in casing seat strategy as well as novel changes in drilling fluid design and selection of Loss Control Material.

Dysfunctions and limiters in drilling which were affecting the hole cleaning, mechanical specific energy (MSE), hydraulics efficiency, and ROP were eliminated.

A detailed analysis of the impact of changes in bits and bottom hole assembly design, drilling fluids design, and casing design is shared in the study for the last fifteen wells drilled in the field. Continuous learning and enhancements in all the subject areas are analyzed with respect to the use of different strategies and technologies. An analysis has been performed for non-productive time, its root cause and successful actions taken to reduce its occurrence. A huge reduction in drilling time, cost and risks have been achieved as a result of mentioned changes in the latest well setting a benchmark in the entire region. Dry hole time for the last well has been reduced by 78 %, while 65% cost reduction is achieved as compared to the previous average time and cost respectively. After removing the dysfunctions / limiters; ROP enhancement of 5 to 10 times has been achieved in different hole sections.

The learning and experience from the use of discussed technologies and drilling practices can be helpful for optimizing challenging wells with the problems of pressure reversals, drilling fluids losses, well control, drillability issues in gumbo clay/ shales and wellbore stability.
Pinpointing Source of Sustained High Casing Head Pressure (HCHP) for Well Integrity Restoration: A Case Study of a Well in the Niger Delta
Authors: Bougha Arthur , Oluleye John , Ivrogbo Daniel , Okonkwo Ngozi
Published: March 2023

Maintaining the integrity of oil and gas wells is of utmost importance. This requires regular monitoring to ensure the barrier envelop is maintained. Sustained pressure in the casing infers a compromised barrier envelop. It poses a serious threat to the well integrity and if not addressed could lead to increased risk of pressure transmission and fluid leakage through the concentric tubulars. The key objective is the ability to accurately pinpoint the source of the pressure.

Modern technologies using through-tubing logging systems are more accurate for leak detection. If the leak is not accurately detected, the sustained high casing head pressure persists and could lead to undesired outcomes even after the repairs. Here, the high accuracy Sonic-Noise Log (SNL-HPT) was deployed through slickline. Data acquisition process involved both shut-in and flowing modes. The shut-in mode required the well to be stable while RIH SNL-HPT tools on slickline for data acquisition. While in the bleed off mode, the well was being produced during data acquisition. A surface choke manifold and flowback tank were rigged-up for flow control.

In this paper the results of well Unut-4 Sonic Noise Log- High Pressure and Temperature (SNL-HPT) surveys are presented. The objective was to investigate the source of A annulus pressure in this well. The data was successfully acquired in memory via slickline up to a depth of 10,000ftah using both shut-in and bleed off (flowing) modes. The shut-in mode required the well to be stable while RIH SNL-HPT tools on slickline for data acquisition. While in the bleed off mode, the well was being produced during data acquisition. The acquired data was successfully downloaded and interpreted for the source of leak. The SNL-HPT interpreted data indicated that the High CHP was caused by communication observed through leaks at depth 9,751ft (the dual packer). The spectral noise logging located the active leak source and verified the integrity of cement barriers while the High temperature logging quantified the leak rate using temperature modelling. This paper would detail the history of the well, planning, design and execution of the successful logging including the interpreted results.

Sonic Noise Log is a simple technology to deploy for accurate leak source determination. In all the instances this was deployed, acquired and interpreted data was good enough for a decision making on the forward plan. The results of this logging led to the early injection of the well in the rig sequence and well was subsequently worked over. Integrity was restored with further deferment of production averted.
Maximizing Recovery and Reducing Well Cost Using Herringbone Multilateral Horizontal Well Drilling and Completion Technology
Authors: Zhang Xiaocheng , Xie Tao , Huo Hongbo , He Ruibing , Lin Hai , Hou Xinxin , Xu Dongsheng
Published: March 2023

With the in-depth development of Bohai Oilfield, China National Offshore Oil Corporation (CNOOC), the water cut of some old wells become too high to produce while nearby remaining recoverable reserves are still considerable. In order to maximize recovery and reduce well construction cost, herringbone multilateral horizontal well drilling and completion technology is employed to increase drainage area of single well and make full use of well slot and old wellbore.

Considering the current development of oilfield and the geological characteristics of reservoir, the technical difficulties of herringbone multilateral horizontal well drilling and completion technology including high build-up rate, easy blockage of drilling tools in the sidetracking in open hole, easy collapse and instability of sandwich wall and high requirements for drilling fluid performance are analyzed and solved.

This technology has been successfully applied in three wells with total 6 branches and the production of three wells is twice higher than that of conventional horizontal wells with no water cut, which fully verified the reliability of the branch well tools and the feasibility of the technology.

Herringbone multilateral horizontal well drilling and completion technology provides a new idea for the treatment of low production and low efficiency wells in a sustainable way and will be widely promoted and applied in Bohai oilfield, which can also provide reference for other high water cut oilfields.
Water Production Diagnostics and Formation Evaluation to Maximize Workover Profitability of ESP Oil Producers Using Electrical Coiled Tubing, Gulf of Suez, Egypt
Authors: Ghonim Ahmed ElSayed , El-Farran Amr Zienhim , Atef Ahmed , El-Abasy Mohamed , Haridy Ehab , Aboeleneein Mohamed Mamdouh , Abdulaziz Sameh Mohamed Hashim , Mohamed Sara Omar
Published: March 2023

Well intervention in highly deviated sour oil wells operating with Electrical Submersible Pump (ESP) completions have always been challenging for well intervention operations due to the restrictions in the wellbore. Workover operations in such harsh environments involve several operational risks and high related costs. Electrical Coiled Tubing (E-CT) equipped with tubing encapsulated mono-conductor cable was used to gather accurate intervention data with real-time logging capabilities. The system used didn't require the temporary installation of a test ESP completion string after pulling the failed ESP pump, saving cost, overall intervention time, optimizing zonal isolation for the water producing intervals, and increasing well recovery in these oil wells.

This case study presents a challenging workover for a mature field where E-CT was used to convey a combination of Pulsed Neutron Logging (PNLT) and Production Logging Tools (PLT) while pumping Nitrogen (N2) to lift the well. This enabled maximizing the reservoir production potential while monitoring the dynamic drawdown being applied to overcome the masking potential for the PNLT due to killing operations during workover. Real-time readings from the PNLT, PLT continuous spinners, gamma-ray, pressure, and temperature sensors accurately identified the well's water contributing intervals and flow profile. This accurate interpretation of the water saturation profile across the reservoir was then used for optimum reservoir management and selective zonal isolation. Dynamic wellbore modeling software was used to design the lifting and logging operations for optimal operational efficiency and to increase oil production and reduce water production.

Deployment of E-CT in such a harsh environment was challenging in terms of operational execution to ensure safe conveyance of the real-time logging tools while performing the conventional lifting of the well. Intervention time was optimized through two runs to evaluate the formation performance and water saturation profile before isolating the water-producing intervals.

Such utilization of E-CT allowed accurate formation evaluation, water saturation profiling, and nitrogen lifting of the well resulting in an optimal intervention. Results showed a 50% reduction in water production and an increasing well potential from the upper intervals. Total workover and intervention costs were reduced dramatically compared to other treatment options for water production problems with potential workover complications and deferred production.
Novel Approach to Identify Sand and Viscous Oil Problems Through the Analysis of Dynamometer Cards and Field Practices
Authors: Chanchlani Kuldeep , Gunwant Deepak , Gogoi Ranjit , Singh Kamal , Dadhich Jeetendra , Rajak Himanshu
Published: March 2023

Problems due to the solids and viscous oil are difficult to predict in the dynamometer cards. An innovative approach is devised to identify solids and viscous oil problems, based on the interpretation of dynamometer card analysis and troubleshooting practices implemented at the field scale. Sand or wax incursion in the subsurface pump causes the pump screen or perforation to choke, resulting in no communication of the reservoir with the tubing. It can cause no free fall of polished rod and sucker rod string getting stuck up. Heavy viscous reservoir fluid shows the standing valve, traveling valve, or both pump seats getting choked. The drag force creates an extra differential force between the plunger and the pump, showing the case of the sucker rod unscrewing or parted as pump seats get choked up in the dynamometer card.

Casing head pressure, pump hydraulics, and the shape of the dynamometer card are critical parameters in differentiating between the fluid pound, gas interference, and blocked pump intake. The plunger stops before opening the traveling valve in case of pump intake is blocked, or the spiky and curvy loads in the dynamometer card due to solids-related problems. During the circulation job, higher pumping pressure taken by the pumping unit ascertains the solids incursion. Viscosity is an important property that determines load distribution on the rod string. The drag force causes the dynamometer card to stretch, but practically the rod is unscrewed or parted. Post-rod string makeup well started producing liquid. It has revived non-flowing wells and prevented production downtime. This unique approach will benefit the operators in analyzing the sand, solids, and viscosity-related problems and troubleshooting these failures of rod-pumped wells. Oil gain has been observed in rod-pumped wells based on this systematic approach.
Challenges of Drilling Deep Wells in a Complex Overburden with Severe Depletion and Experiences From Caspian Sea
Authors: Al Saadi Anwar Juma , Naidu Rajarajan Narayanasamy
Published: March 2023

The objective of this paper is to share Dragon Oil's experience to overcome challenges in drilling deep depleted reservoirs in the Cheleken Contract Area, Caspian Sea, Turkmenistan. Dragon Oil operates two producing oilfields; Lam and Zhdanov. The main targets described in this paper are from the Zhadanov field with the deepest target reaching around 4000m. This paper describes the challenges and experience from drilling complex wells in this area.

The wells described in this paper penetrate various depleted reservoirs due to past production. The deepest reservoir consists of a sequence of interbedded sands with varying pore pressure due to geology and depletion due to production. The intra-reservoir shale layers are unstable and require high Mud Weights, often reaching technical limits (up to 20 ppg).

The requirement of high mud weight to address shale instability is in contrast with the solutions for drilling depleted sand and the common drilling risks are mud losses and stuck pipe. An analysis of challenges, risk mitigations and lessons learned are discussed in this paper.

Drilling a deep 6" directional hole is challenging and it requires continuous monitoring of the drilling fluid density. The pre-drill well planning is a key solution for preparing to deal with operational challenges and develop a strategy for reducing risk. This paper describes the important steps followed in the well planning process, risk mitigation options analyzed and incorporating the key elements in drilling program to overcome challenges.

Some of the lessons learned from the experience of delivering wells in such complex area are: Implement 3D/4D PPFG and wellbore stability models to communicate depletion magnitudes accurately and effectively incorporate the risk in well planning to enable drilling with minimum overbalance.Map the correlation between depleted sand bodies (e.g. facies model) and assess impact of fault typesImplement Synthetic Oil Based Mud to improve wellbore condition and enhance drilling performance.Choose well trajectories to help transfer weight/torque to bottomMinimize the BHA static time across severely depleted zones

This paper shares the experience from Turkmenistan and lessons learned from Dragon Oil's operations in Caspian Sea. This paper consolidates the well planning process, methods adopted to incorporate risk mitigation into drilling program and our recent experience from drilling complex wells targeting deep depleted reservoirs.
Research on Pore Pressure Prediction Technology of HTHP Wells in South China Sea Based on Machine Learning
Authors: Xu Dongsheng , Yang Jin , Zhao Yuhang , Fan Jianchun , Li Yanjun , Liu Xun , Chen Kejin , Song Zehua , Zhang Xun , Zhu Hong
Published: March 2023

The Yingqiong Basin in the South China Sea is located at the intersection of the Eurasian and Indo-Chinese plates, with complex geology and often accompanied by abnormally high pressure. In this paper, we analyze the causes of anomalous high pressure in the South China Sea and analyze the commonly used machine learning methods, support vector machine and BP neural network, and use both methods to predict a block in Yingqiong Basin. The field application was carried out using this method, and the application showed that the prediction accuracy exceeded 95%, the complexity was reduced by 42%, and the drilling efficiency was improved by more than 53%, which played a good guiding effect to the field.
Innovative Performance Models for Integrated Projects in Offshore Deepwater Operations
Authors: Nunez Davila Andres Felipe
Published: March 2023

Integration in offshore drilling environments was traditionally limited to bundled services and managed by a project manager. The success of the integration model was mainly related to equipment logistics and quality assurance. The objective of this paper is to describe how the traditional model has evolved from a bundled long-term service commercial relationship to the innovative performance award model that has been implemented in an integrated project in the Gulf of Mexico.

The offshore and deepwater drilling environment is characterized by its high operating cost; thus, risk management is one of the key aspects for the project's success. The oil and gas industry has continuously evolved during the last decades, moving toward digital and automation technologies and applications. The new performance model is based on a time definition and further estimation of budget required. Factors are linked to specific rewards in case the predefined objectives are achieved. The associated risks definition becomes critical to ensure the predefined estimates are achievable. To support the risk management process, the application of digital solutions support the planning and execution stages.

The multiwell performance analysis and benchmarking tool enables us to evaluate the historical results and comparison between rigs, including and not limited to determining the project baseline, identifying the historical invisible lost time, and defining the main areas of improvement.

This tool supports the definition of the risks factors and provides the inputs to determine the most accurate project budget.

For the execution, one of the historical associated risks was related to the drilling fluids and well integrity. It is commonly found in the area for wells to be drilled under narrow operating windows and having extended sections. The increase of frequency and accuracy of drilling fluid properties verification is fundamental to ensure the system is under the required parameters and properties limits previously determined. The automated rheometer has been developed to increase the frequency and accuracy of rheological drilling fluid properties, thus minimizing the impact of one of the most relevant risks across the area.

Finally, the focus to optimize the schedule and logistics was based on synergies developed across the different services involved. This included activities that are carried out from a single point of contact, eliminating the duplication in tasks and minimizing the resources required.
Real-Time Autoregressive Deep Learning Framework for In-Line Automatic Surface Logging
Authors: AlShehri Abdallah , Katterbauer Klemens , Yousef Ali
Published: March 2023

4th Industrial Revolution (4IR) technologies have assumed critical importance in the oil and gas industry, enabling data analysis and automation at unprecedented levels. Formation evaluation and reservoir monitoring are crucial areas for optimizing reservoir production, maximizing sweep efficiency and characterizing the reservoirs. Automation, robotics and artificial intelligence (AI) have led to tremendous transformations in these areas. From AI inspired well logging data interpretation to real-time reservoir monitoring, technologies have led to cost savings, increase in efficiencies and infrastructure centralization. In this work we provide an overview of how autoregressive deep learning methodologies can lead to major advances in the field of formation evaluation and reservoir characterization, providing a comprehensive overview of the technologies developed and utilized in this domain. Furthermore, we provide a future outlook for smart technologies in formation evaluation, and how these sensor-derived data can be integrated. This also describes the challenges ahead. Future developments will experience a growing penetration of 4IR technology for enhancing formation evaluation in subsurface reservoirs.
Interactive Analysis (IRA) Determining Focal Reservoir Parameters Dominating Estimated Ultimate Recovery (EUR)
Authors: Shan Youngbin , Wu Yaoguang , Hu Aiguo , Li Fanlei
Published: March 2023

Interactive Analysis (IRA) is a new reservoir study method which applies to both condensate oil & gas reservoir and conventional oil & gas reservoir.

IRA establishes the correspondence between stage EUR equivalents and reservoir parameters.

Often, reservoir parameters include but not limited to porosity, permeability, burst pressure, Poisson rate, Oil saturation or Gas content, Free gas content and adsorption gas content, pay zone thickness, resistivity, mud content, etc.

In a specific compartmentalization, it is important to decide which parameter is the focal parameter dominating the productivity. If the focal parameters can be decided, operators can use this evidence to decide which zone and which sub-zone drilling must fully penetrate through. Additional, when well is designed for hydraulic fracturing, engineers can use this data to design stages and clusters. Designing of higher focal parameter quality in stage and cluster is certainly a contribution to better frac efficiency and EUR.

IRA is expressed that the Normalized Correlated Coefficient (NCC) Vector is equal to the Moore-Penrose inverse of the Normalized Reservoir Parameter Quality Factors (NRPQF) matrix multiplying the Normalized EUR equivalent (NEE) vector. NCC deriving from the IRA represents the weight of productivity contribution to EUR.

Analyzing IRA equation, the focal parameters dominating the well EUR can be determined. With focal parameters available, operators can optimize the drilling criteria and optimize frac design.

For a specific compartmentalization, the focal parameters derived from IRA shall give consistent focal parameters which dominate the higher productivity and lower productivity. When a well is hydraulic fractured, the NEE can be tested and analyzed. To input the NEE into IRA equation, the frac efficiency is also reflected by NEE.

Three shale gas wells in a compartmentalization are analyzed via IRA analysis. The positive focal parameters, irrelevant parameters and negative focal parameters in each well and overall averaging give good convergence.

Two wells in condensate oil pay zone in a compartmentalization are also analyzed via IRA analysis. The positive focal parameters, irrelevant parameters and negative focal parameters in each well and overall averaging give some convergence.

If a NCC is bigger, it dominates EUR. If it is small or very small, the contribution to EUR is less or measily. On the other hand, if a NCC is positive, it increases the productivity when the parameter quality is higher. If a NCC is negative, it decreases the productivity when the parameter quality is higher.

No focal parameter dominating EUR can be understood until IRA is proposed.

Rather than reservoir mechanics analysis, IRA gives explicit linear mathematical expression which makes engineers easier to calculate by aid of Matlab coding.

IRA analysis is a breakthrough to understand the intrinsic structure between reservoir parameters and EUR.
A Review: Progress of Diverter Technology for Oil and Gas Production Applications in the Past Decade
Authors: Li Wengang , Sahu Qasim
Published: March 2023

Diversion technologies is becoming widely used as part of multistage fracturing operation and acid stimulation especially in carbonate formations completed with extended reach or multilateral wells. Further importance is gained during the development of unconventional resources where large number of stages are required with enhanced stimulated reservoir volume (SRV) per fracture. This is achieved by improving the fracture network and complexity using far field or deep diversion techniques. Diversion gained more value since it was an enabler for more efficient refracturing jobs since it can divert treatment from existing fractures. One of the main functions of diverters is to direct the stimulation fluid toward the desired treatment interval to increase the efficiency of productivity enhancement process.

A diverter could be either mechanical or chemical. Mechanical diverters include packers, ball sealers, coil tubing, and particulate diverting agents such as benzoic acid flakes, rock salts, wax beads and fiber. Chemical diverter is mostly used as temporary barrier of fluid during treatments, and will get converted back afterwards by chemical means. Chemical diverter can be divided into two main types: polymer-based diverter and surfactant-based diverter. In the past decade, biodegradable diverter has been developed according to the concern of both environmental protection and less formation damage. Relative permeability modifier (RPM) can also be used as diverter in some cases. All the above diversion techniques will either divert the fluid in the wellbore or deep inside the formation based on the objective of the treatment and type of fluid used.

This paper covers diverters in both injectors and producers with the applications of matrix acidizing, acid fracturing and hydraulic fracturing. In matrix acidizing, polymer-based acid gel is one of the most applied diverters. Adding N2/CO2 to form foamed acid, the treatment efficiency could be further enhanced with less formation damage. Viscoelastic surfactant (VES) improved acidizing was also applied in many cases. Fiber based acidizing fluid proposed to be effective in carbonate formation. Multi-stage acid frac jobs were done in 2011 in tight gas carbonate formations. A new trend of acid frac is to use CO2 energized fracturing fluid for tight, sour gas formations. Far-field fracturing mechanism was studied by means of solid particulate diverting agents. Eco-friendly and biodegradable diverters were applied for zonal isolation. Nanoparticles, as new generation of diverters, have been used for EOR as foaming agents since beginning of this decade, especially at HTHP conditions; nanoparticle stabilizers were applied in polymeric gel and VES system to enhance the stability for diversion fluid.

To make the best performance of diverters, limitation on working conditions of each type of diverter would be identified, such as cost, temperature range, pH range, size distribution, and compatibility with fluid additives.
Successful Analysis of Acoustic Sand Monitoring in Tandem with Online Sand Sampling to Safeguard and Optimize Production in a Mature Oil Field
Authors: Chin Alvin Zhi Siang , Roh Cheol Hwan , Noordin Fuad , Zainul Zaimi , Ho Dylan Zhe Xin , Basri Hakim , Chandrakant Ashvin Avalani , Zin Zulkifli , Rosland Eadie Azahar , Ambrose Jonathan , Taha Adam
Published: March 2023

This paper serves to share the findings and best practices of sustaining production for a mature field with high sand production with analysis from Acoustic Sand Monitoring (ASM) paired with Online Sand Sampling (OSS). Field B, located in the East Malaysia Region, is a high oil producer for over 40 years under a strong water drive mechanism. Water production has significantly increased over the past 5 years, which has led to significant sand production impacting surface facilities and well integrity. Hence, the need for a reliable and efficient sand management surveillance in field B.

As the first application for oil fields in the region, ASM and OSS was conducted with the objective to determine the maximum sand free production rate from over 80 active strings in Field B over the span of 4 months to safeguard production rates of 10 kbopd. With ASM and OSS, a reduced data surveillance duration can be achieved within 2 hours compared to conventional well sand sampling per well which requires a minimum of 24 hours before sand production rate is determined. ASM sensors are clamped on the well flowline to detect and record the noise vibrations produced by the sand while OSS is conducted concurrently by diverting parts of the same flow from the flowline through a sand filter to have a quantitative representation of sand produced for a predetermined duration.

During the campaign, choke sizing was manipulated to control reservoir drawdown. For most wells, a lower drawdown resulted in lower amplitude readings from ASM and less sand observed from OSS. However, there are several wells that had higher sand production at a smaller drawdown due to a change in flow regime (steady flow to intermittent flow) resulted from inefficient gas lift production (multi-pointing). As ASM provided the raw velocity signal which is heavily influenced by the liquid flow regime, gas oil ratio and sand production, OSS results (from physical sand produced and weight of sand particles) established a baseline for ASM signals which indicate a sand free production. Overall, ASM and OSS analysis provided a baseline for determining the optimum rate of production with minimum sand to avoid well integrity issues and protecting the surface facilities, thus allowing continuous field production of 10 kbopd.

A presentation and discussion of the successful results, limitations, best practices, and lessons learnt of the ASM and OSS campaign aspires to be additive to the production surveillance sand management in the oil and gas industry by providing a fast and reliable means of identifying optimum sand free production rates for a high number of wells in a mature field.
Practical Imaging Applications of Wettability Contact Angles on Kuwaiti Tight Carbonate Reservoir with Different Rock Types
Authors: Al-Sayegh Saleh , Flori Ralph , Al-Bazzaz Waleed , Kholosy Sohaib , Al-Saedi Hasan , Abbas Abdulaziz , Qubian Ali
Published: March 2023

This study focuses on a tight carbonate reservoir which is located in Northern Kuwait and is classified as an unconventional reservoir. A practical imaging technique of wettability contact angle (θ°) presents "big data" as well as relative-permeability (Krw and Kro) measurements. Also, modeling, through rock image technology, the vast well-documented grain/pore boundary morphology available inside fresh rock fragments have achieved good results. Conventional laboratory relative-permeability experiments are expensive and time-consuming. This study introduces a novel method to measure/calculate relative permeability through fast, less expensive, non-destructive, and environmentally friendly techniques of imaging technology. One tight carbonate reservoir is selected, imaged, processed, analyzed, and then modeled using several pore diameter morphological models. The images are captured using a backscattered electron microscopy BSE-SEM technology analyses.

In this study, two-dimensional images are used to characterize the morphology of selected samples grains and pores, using a two-step technique. In the first step, the image is captured using a backscattered electron detector (BSE), digital electron microscopy imaging, and pore-counting processing technology. All of the sample grain/pore features captured in the image are reported in micrometer units. In the second step, the pore area of such features is scanned using image analysis software that can accurately measure several morphological parameters of pore and grain spaces.

A robust technique of visual estimate is used, which has the advantage of speeding the image analysis process. The visual analysis software tool counts different pores and counts grains and also measures their shapes and sizes which are crucial for relative permeability calculations. Several pore morphological models have been considered for optimum accuracy comparisons, including pore/grain relationships (area/perimeter), pore contact angle (θ), and pore count. Relative permeability is calculated based on the area of the pore/grain features measured from two-dimensional images.

The study objectives are to accurately measure the wettability contact angle of huge pore geometries using 2D image technology to understand the nature of the pore network in the candidate reservoir. To study the relative permeability of internal influences of pore and grain morphology needed for enhanced oil recovery/improved oil recovery (EOR/ IOR) future programs. And, finally, to measure relative permeability faster and more accurately.