bluuebunny/crossref_metadata_2025_split huggingface dataset:
Improving the Approach to Assessing the Production Potential from Well Interventions for Mature Fields with a Large Well Stock
Authors: Sun Darya , Yudin Evgeny , Slabetsky Andrey , Vorobyev Dmitry , Studinskiy Roman , Martynyuk Roman , Chervyak Artem 
Published: November 2022

Abstract
This paper describes a comprehensive solution for the management of technological and economic potential, implemented using a digital information system (IS) - SPecTR, which includes a section of the Unified Register of geological and technical measures with automatic selection and multi-user expertise of geological and technical measures in the production and injection stocks, as well as Well Intervention Efficiency Monitoring section.
A significant advantage of the information system under development is the maximum automation of the entire selection process and subsequent monitoring of success: from the input data needed to calculate, i.e. technological modes of operation of wells, isobar maps, porosity and permeability, initial and residual oil saturated layers, well logging data interpretation results, well coordinates, charts, PVT data, etc., - to to determination of the risks to the performance of light and heavy well interventions for each specific well, calculating incremental oil flow rates and economic viability for the selected well intervention candidates, conducting factor analysis of achieving the planned effect of well interventions, etc.
The described system provides for a unified approach to determining the technological (production) potential for various Gazprom Neft's assets. At the same time, the system can be called flexible since it enables users from various Subsidiaries to "customize" the candidate selection process with account of specifics of their assets: by including additional selection criteria in the selection process, adjusting thresholds, setting well intervention design parameters for calculating the target conditions, etc.
The SPecTR system is currently implemented and has been undergoing commercial operation at 9 Subsidiaries of Gazpromneft.
Geothermal Energy in Caspian Region: Study of Heat Extraction Methods from Deep Wells
Authors: Abdrazakov Dmitriy 
Published: November 2022

Abstract
Geothermal energy currently occupies an insignificant role in the renewable energy balance. This is explained by its low heat flow rate and the significant investments associated with heat mining. However, the geothermal heat flow is continuous and non-interruptible and occurs everywhere in the lithosphere. Existing oil and gas fields’ subsurface and surface infrastructure and expertise can significantly decrease capital expenditures for geothermal heat extraction. Taking this idea as a basis, the study of geothermal heat production from existing oil and gas fields of the pre-Caspian region of Kazakhstan was performed.
Since this work is one of the first attempts to estimate the geothermal heat potential of the existing oil and gas industry infrastructure in Kazakhstan, the study consists of two big parts. First part is the detailed theoretical review of the geothermal heat extraction methods which may be potentially applied in Kazakhstan. Special attention in the literature review section was given to enhanced geothermal systems and closed loop systems, because they have many technologies in common with the oil and gas industry (completion concepts, hydraulic fracturing etc.). Second part is the quantitative estimation of the geothermal potential based on twenty oil fields, with several wells in each field as trial sites. Quantitative estimation considers pragmatic and optimistic scenario of future investments.
The study showed that even in the pragmatic scenario in which the water-producing wells are turned into hydrothermal producers, the recoverable effective heat reaches 420 TJ in total for all wells in the selected fields. However, the demand for the geothermal heating of the industrial and household objects near the selected fields was estimated to be three times higher. Thus, a more proactive geothermal strategy was considered. This strategy yields ~9800 TJ of recoverable effective heat, which covers the demand and provides excess for the growth. Based on the reservoir properties and economic perspective estimations, it was defined that enhanced geothermal systems and closed loop systems will be less abundant in the given region in a short term. However, with development of the geothermal technologies and increase of investments, these systems may have increased importance. On the other hand, direct hydrothermal producers and well doublets (injector connected to producer through the permeable reservoir), most probably, will be a prevailing method of the geothermal heat mining in the pre-Caspian region of Kazakhstan in the short and medium terms.
Facies Modelling in Thin Bedded Heterogeneous Reservoir – A Case Study from Dunga Field Aptian Reservoir
Authors: Ospanova Assel , Pinto Pedro , Takirov Zhandos , Runge Trevor , Mukherjee Supriya , Melvin Angela 
Published: November 2022

Abstract
The Dunga field Aptian reservoir is very thin bedded and heterogenous at a fine (cm) scale below log resolution and presents distinct challenges for reservoir modelling. This paper describes methods for upscaling detailed thin bed reservoir description and facies mapping from core and log data to build a 3D geological facies model.
The Dunga Field is penetrated by approximately 190 wells, of which 9 are cored. Field wide correlation of the main reservoir units is sub-seismic and below biostratigraphic resolution. A novel method using step outs (cluster correlations) from the key cored wells to the closely spaced vertical well penetrations has provided a more detailed correlation and mapping of reservoir units. The method has provided consistent and field wide definition of depositional trends and architecture of deltaic mouthbars which form the main reservoir sandbodies.
Facies modelling of the heterogeneous reservoir was built by integrating and upscaling detailed core data, well data and depositional trends. Four facies, identified from log and core evaluation, are modelled using stochastic method (SIS), where facies fraction was controlled by up-scaled cells. The variogram directions of facies model are guided by sand body depositional trends. Depth appropriate facies probability maps are used for modelling clean sand and heterolithics facies to guide facies distribution.
The detailed study carried out to build the 3D geological facies model is helping to achieve better production history matching and is being used for future well planning.
First Successful Double Casing Window Opening in HPHT Well in MCA
Authors: Cruz Andrea , Caballero Guillermo , Melo Elías , Almendra Denis , Noguez Mario , Hernández José 
Published: November 2022

Abstract
The recent decline in crude oil production has needed more subsurface explorations to sustain and increase oil production in Mexico. The Client has discovered high potential fields with wells around 7,500 m (24,605 ft) to 8,200 m (26,902 ft) with high pressure, high temperature and hard formation features.
On deep HPHT wells, many challenges have been identified for drilling and completion, which can lead to the execution of challenging operations for reaching the objective of the well.
It is common to sidetrack the wells due to geological or mechanical failures. In Mexico, around 430 jobs were performed successfully in large casing sizes such as 9-5/8", 11-3/4" and 13-3/8" onshore and offshore. What is uncommon is to sidetrack the wells in smaller casing sizes (9-5/8" and 7"), with non-conventional grades, such as TAC-140, which is only used in Mexico with the record of three unsuccessful jobs (two onshore wells and one offshore well) to this day.
The work presented here aims to share the process of opening a window in a dual casing in hard steel (TAC-140) in a very complex and challenging environment.
Application of Machine Learning Techniques for Rate of Penetration Prediction
Authors: Safarov Asad , Iskandarov Vusal , Solomonov David 
Published: November 2022

Abstract
In this paper, several supervised machine learning algorithms have been used to develop the model for rate of penetration prediction. To train the models, real-time drilling parameters and geological log data from 3 distinct wells in the South Caspian basin are used. The different machine learning techniques, such as linear and non-linear machine learning and deep artificial neural networks, trained the well data. The evaluation metric for training is Root Mean Square Error, however the performances of the regressions are evaluated on the data using R-squared for their comparison.
Rate of penetration, or simply ROP, is the speed of the drill bit penetrating into the formation. Overall, it indicates at which rate the borehole deepens. Its value depends on the drilling parameters, such as weight on bit, applied torque, mud flow rate, rotation per minute and others. In addition, the mechanical strength of the rock formation also plays a great role, and well log data is used to assume this value for each point. That is why these features in the training datasets have high vulnerability.
Comparing various techniques, Random Forest gives us the most optimal model in terms of accuracy and computational power. The average R-squared for Random Forest is 0.90. Although RNN and LSTM models can give nearly the same fit for given test data, it takes considerably much more time to train the models due to their complexity and show relatively lower accuracy on test data, therefore it is not a reasonable choice. Furthermore, another deep learning model is deployed to generate well logs for the following sections which supports optimizing ROP and drilling performance.
Model for Nonsteady Water Removal from Horizontal Gas Wells
Authors: Samolovov Dmitrii , Apasov Renat , Varavva Artem 
Published: November 2022

Abstract
The paper considers the process of removal and accumulation of liquid in horizontal trunks of gas wells and land gas pipelines. A mechanistic model of the process is constructed, an equation is derived that describes the dynamics of the process of removal and accumulation of liquid, criteria for the removal of liquid are determined, as well as the main dimensionless factors that affect the nature of the process. A method for static analysis of the area of stable operation of a well is proposed. The results of the work can be used in designing the trajectories of projected horizontal gas wells, to evaluate the operation parameters of actual wells and gas pipelines, and to plan measures for cleaning horizontal gas wells from liquid.
Feasibility Study of a Polymer Flood for the Uzen Brownfield Conditions
Authors: Imanbayev Bakyt , Kushekov Ruslan , Sagyndikov Marat , Shyrakbayev Damir 
Published: November 2022

Abstract
The Uzen field development stage is characterized by high watercut (~90%) due to long-term waterflooding and a recovery factor of 34,6%, which is appropriate for moving to the tertiary recovery methods, especially chemical EOR. Polymer flooding (PF) is a promising chemical EOR technology to provide incremental oil and extend the field life. Therefore, the main features of PF were investigated and screened for the Uzen field conditions within the scope of the feasibility study.
The main geological characteristics of the reservoir were examined to confirm polymer flooding applicability. Reservoir dynamics analysis was conducted to identify the main problems of the current development strategy. Water composition analysis was carried out to assess available water sources in terms of polymer compatibility. Based on Daqing oilfield PF experience, the watercut dynamic behavior was used to determine incremental oil amount for the potential pilot area in Uzen. Since technical feasibility studies are done, economical feasibility has been conducted considering current oil prices.
Parameters such as temperature, permeability, oil viscosity, and brine salinity were found to be the most critical for polymer flood. Two water sources out of three available in the Uzen showed the compatibility of polymers according to water composition analysis. The first priority is given to Cretaceous formation brine as the most appropriate and the second priority is given to Caspian seawater. The potential pilot area with 3 injectors and 14 producers has been selected and forecasted in terms of PF production. PF technology performed for 10+ years resulting in 4.7% of incremental oil recovery. Polymer flooding has proven to be an effective development strategy as a tertiary recovery method that hopefully will be applied in the coming years.
Although polymer flooding has been used for the past ~60 years, for the Uzen field polymer flooding is a step away from being applied for the first time. Observations and obtained results are the basis for future design, implementation, and optimization of PF in the Uzen oilfield.
World's Longest DTS Cable Run for Permanent Monitoring Below ESP - A Successful Solution for West Siberian Wells Surveillance with ESP Systems - Case Study
Authors: Nifontov Nikita , Maltsev Andrey , Vikulin Nikita , Ten Petr , Torsunov Nikolay 
Published: November 2022

Abstract
This article describes evolution of well design concept for Vikulovskaya oil rim reservoir development with no possibility for fracking and first World's longest application of permanent monitoring solution for appraisal multilateral well with the access to the wellbore restricted by presence of ESP pump in West Siberia inside 7″ casing and 4.5″ production liner Horizontal Multilateral well.
Laboratory Investigation on Cryogenic Fracturing of Coal Rocks: An Experimental Study in Kazakhstan
Authors: Longinos Sotirios , Tuleugaliyev Mirlan , Serik Alina , Wang Lei , Hazlett Randy 
Published: November 2022

Abstract
Cryogenic fracturing with liquid nitrogen (LN2) has been identified as a feasible and promising waterless fracturing method for coalbed methane extraction for its environmental safety and effectiveness. Though it performed well in certain field tests in the late twentieth century, the use of LN2 as the fracturing fluid is still largely unexplored. This research work examines the thermo-mechanical properties of coal specimens from the Karaganda basin in Kazakhstan. Coal specimens were subjected to LN2 treatment under varied lab-controlled conditions, such as the freezing time (FT) length and number of freezing-thawing cycles (FTC), both in dried and water-saturated conditions. SEM investigation for FTC and FT experiments for dried coal samples indicated that the LN2 freezing-thawing process can enhance the cryogenic fracture extent and the fracture interconnectivity. Moreover, uniaxial compressive tests indicated that compressive strength decreases beneficially with an increase in both the number of freezing-thawing cycles, while water-saturated experiments indicated substantial change after liquid nitrogen treatment compared to dried ones.
Improving the Operation Efficiency of Deviated Wells with High Oil Viscosity Values and Abnormally Low Reservoir Pressures
Authors: Isaev Anatoliy Andreevich , Takhautdinov Rustem Shafagatovich , Malykhin Vladimir Ivanovich , Sharifullin Almaz Amirzyanovich , Aliev Mekhrali Mirzali ogly 
Published: November 2022

Abstract
Hydraulic fracturing of a formation causes its partial destruction; the subsequent operation of wells is frequently complicated by the release of solid particles (mechanical impurities) from the bottomhole, as well as by the inflow of loose proppant particles into the pump. The authors show how the occurrence of mechanical impurities in the produced fluid affects the operation of downhole installations and the number of well maintenance operations. The paper provides information on the results of measures implemented to prevent mechanical impurities from getting into the pump, whereupon the situation with wells complicated by mechanical impurities has significantly improved. To improve the efficiency of operation of curved wells with high oil viscosity values and abnormally low reservoir pressures, various downhole sucker rod pumps and new solutions for sucker-rod screw pump (PCP) installations have been developed. The analysis of existing PCP designs was carried out.
The today's key strategy of Sheshmaoil Management Company LLC (Republic of Tatarstan, Russia) is to maintain oil production by applying highly effective well interventions (WI), i.e. hydraulic fracturing (HF) [1, 2]. This method of reservoir stimulation has been massively implemented in all seven production companies of Sheshmaoil Management Company LLC since 2014. Mainly transition to such type of WI is connected with abandoning of ineffective methods of production stimulation with various options of acid treatment:
– acid treatments of bottomhole zones; – large-volume selective acid treatments; – acid hydraulic fracturing; – foam-acid treatment.
Combination of WFT and Conventional Well Testing Methods to Effectively Reduce the Time for Hydrocarbons Exploration in Tight and Fractured Suprasalt Carbonates Field in West Kazakhstan
Authors: Shutang Zhin , Blinov Vladislav , Filimonov Anton , Fu Gongwei , Shteynbrenner Kirill , Onggarbay Zhan-Tore , Zhabagenov Muratbek 
Published: November 2022

Abstract
Low-porosity post-salt carbonate reservoirs of Carbonian and Devonian age at Pre-Caspian Region of West Kazakhstan have complex pore structure which cause significant uncertainties in petrophysical properties estimation based on standard wireline logs and subsequently time-consuming and less informative tests in the production string. Therefore, an integrated approach was proposed and applied, involving advanced wireline formation testing methods (WFT) to refine the petrophysical logging results and to optimize the formation tester program and significantly reduce time for dynamic fluid Well Testing in exploration wells.
The new approach integrates methods of WFT using modern technologies which allow to test ultra-low permeability formations. Thus, uncertainties in petrophysical properties such as saturation and fluid contacts are significantly reduced with the use of WFT and allowed to put together optimized and effective formation testing program. The approach described below has helped to cut down the time for Well Testing and brought in valuable information to clarify geological structure and to evaluate oil and gas content of explored reservoirs horizons.
Application of the Wellbore Imaging Tools in Tengiz Field
Authors: Issayev Duman , Sargunanov Marat , Manakhayev Ruslan , Se Yegor , Thornton Dean 
Published: November 2022

Abstract
This paper provides an overview of the borehole imaging tools (BIT) run in the Tengiz-Korolev field giant carbonate reservoirs located in Western Kazakhstan.
Borehole imaging tools have historically been run in Tengiz-Korolev fields both wireline-conveyed and in logging-while-drilling (LWD) conditions. These tools provide indirect images that are derived from a high-density grid of electrical, ultrasonic and formation density measurements. Understanding the distribution of vugs and fractures in carbonate reservoirs greatly enhances the correctness of any proposed flow modeling and, through better plans for drilling and completion, improves production. There have also been successful attempts in generating core-like images based on high-resolution electrical resistivity data recorded in Tengiz's unique "non-conductive" oil-based mud environment. Validation of existing core data with resistivity image log-based fracture picks was performed and encouraged the log-based fracture characterization workflow at wells. Incorporation of the BIT interpretation results confirmed the depositional settings and rock types of interest in both tight matrix and naturally fractured reservoirs.
Understanding the distribution of fractures and karst properties across the conceptual geological regions allowed for calibration of the static and dynamic models. On top of the reservoir model, the implementation of the BIT analysis results helped to constrain key subsurface uncertainties in the principal stresses of the Tengiz 3D mechanical earth model, which is of first order importance for fault reactivation and development of shear zones. The interpretation results allowed determination of the maximum horizontal stress direction from both drilling-induced tensile fractures and borehole breakouts in image-logged intervals.
Currently, the imaging tool is included in the standard well logging program of the field, and characterization of the field utilizing these datasets is ongoing.
A redundancy allocation problem for a series-parallel system with multiple choice technologies considering fuzzy sense with ambiguity and vagueness
Authors: Maji Anushri , Duary Avijit , Bhunia Asoke Kumar , Mondal Shyamal Kumar 
Published: November 2022

Abstract
This study deals with a redundancy allocation problem (RAP) for a series-parallel system with multiple choice technologies contained in each subsystem. The aim of this study is to solve the multi-objective optimization problems by maximizing the system reliability and minimizing the system cost subject to the volume and weight constraints considering three different cases such as (i) crisp, (ii) fuzzy and (iii) fuzzy with ambiguity and vagueness. These multi-objective optimization problems have been solved by applying two methodologies, viz. elitist non-dominated sorting genetic algorithm (NSGA-II) and Global Criterion Method (GCM). To justify all these models, four numerical examples have been considered and solved. Then the simulated results have been discussed with respect to different cases and methodologies. Also to observe the impact of some vital parameters on system reliability and system cost, sensitivity analyses have been carried out.
Zebrafish pancreatic β cell clusters undergo stepwise regeneration using Neurod1-expressing cells from different cell lineages
Authors: Matsuda Hiroki , Kubota Yukihiko 
Published: November 2022

Abstract
Pancreatic β cell clusters produce insulin and play a central role in glucose homeostasis. The regenerative capacity of mammalian β cells is limited and the loss of β cells causes diabetes. In contrast, zebrafish β cell clusters have a high regenerative capacity, making them an attractive model to study β cell cluster regeneration. How zebrafish β cell clusters regenerate, when the regeneration process is complete, and the identification of the cellular source of regeneration are fundamental questions that require investigation. Here, using larval and adult zebrafish, we demonstrate that pancreatic β cell clusters undergo a two-step regeneration process, regenerating functionality and then β cell numbers. Additionally, we found that all regenerating pancreatic β cells arose from Neurod1-expressing cells and that cells from different lineages contribute to both functional and β cell number recovery throughout their life. Furthermore, we found that during development and neogenesis, as well as regeneration, all β cells undergo Neurod1expression in zebrafish. Together, these results shed light on the fundamental cellular mechanisms underlying β cell cluster development, neogenesis, and regeneration.