bluuebunny/crossref_metadata_2025_split huggingface dataset:
Transport Behavior of Liquid Hydrocarbon in Shale Matrix with Mixed Wettability Nanopores
Authors: Zhao Guoxiang , Yao Yuedong , Adenutsi Caspar Daniel , Wang Lian , Sun Fengrui 
Published: October 2021

Abstract
Shale oil is an unconventional petroleum resource which has high total organic carbon (TOC) content and abundant nanopores. The transport behavior of oil through organic rich shales cannot be described by the classical Darcy law due to its complex pore structure and the complicated distribution of organic matter, which results in nanoconfined effects. In this work, on the basis of the boundary slip phenomenon and the fractal scaling theory, a model for oil transport in shale matrix is established considering nanoconfined effects and adsorbed organic matter. The results show that it is necessary to make correction of viscosity and the boundary slip length in order to accurately describe the flow behavior of oil in shale matrix with mixed wettability nanopores. Long chain molecules are more sensitive to nanoconfined effects, especially when adsorbed organic matter is considered. Also, the oil transport capacity in organic shale matrix is greatly enhanced compared to the classical no-slip permeability model. Meanwhile is the oil transport capacity is significantly reduced in inorganic shale matrix. This work shows that the identification of higher TOC region and considering the nanoconfined effects are necessary from the concept of oil transport in shale matrix.
Produced Water Quality: Uncovering the Effects of Centrifugation for Water and Chemical Floods Using a Dispersion Analyzer
Authors: Almorihil Jawaher , Alsmaeil Ahmed , Kaidar Ziyad , AlSofi Abdulkareem 
Published: October 2021

Abstract
A second stage of gravity settling with the addition of demulsifiers or clarifiers is commonly used in processing plants to further treat the separated produced water. In previous work, we demonstrated gravity settling lower efficiency in removing oil carryover from produced water compared to other processing techniques. Both centrifugation and filtration were found to significantly improve the separated water quality. In this work, we focus on centrifugation and further evaluate its efficiency in improving the quality of separated water for both water and chemical floods, specifically surfactant/polymer (SP) flooding.
Samples were firstly prepared to imitate the separation plant projected feed and operations. Synthetic representative brines were prepared and used with dead crude oil to prepare the oil/water emulsions. Emulsion separation was conducted at different temperatures, as well as different concentrations of SP, and the demulsifier. The kinetics and efficiency of separation were thoroughly studied over two stages of separation: primary gravity settling and secondary centrifugation. We performed gravitational separation using bottle tests in order to firstly obtain the separated produced water for use in secondary water treatment studies and to secondly further investigate gravity settling kinetics and efficiency. Water quality, in terms of oil content, was then assessed through solvent extraction and UV analyses. Samples of the produced water separated by the primary gravity settling were then exposed to secondary centrifugation. Centrifugation was performed at different rotational speeds using a dispersion analyzer. Light transmission evolution in space and time was used to study kinetics, efficiency and mechanisms of secondary centrifugation.
The results reconfirmed that a single-stage gravity settling is not sufficient to reduce oil carryover to acceptable levels for disposal and re-injection into oilfields. Secondary centrifugation yielded clear and significant improvement in water quality even in the presence of EOR chemicals. With centrifugation, the separation efficiency was a function of the rotational speed. Higher rotational speeds resulted in higher creaming velocities and faster separation. In addition, creaming velocities indicated that higher temperatures yield favorable effects on oil droplets migration and separation rates. This is possibly due to the lower density and larger bouncy at higher temperatures.
Based on these results, we conclude that secondary centrifugation is very efficient and effective in improving the quality of separated water. In terms of the effects of investigated EOR formulations, SP addition caused minor but manageable reduction in separated water quality at a level that would not harm conventional disposal practices.
Evaluation of High Dissolving-Power Retarded Acid Recipes for Carbonate Acidizing
Authors: Aljuryyed Norah , Al Moajil Abdullah , Alghamdi Saeed , AlDarweesh Sajjad 
Published: October 2021

Abstract
Development of retarded acid recipes that can have both adequate dissolving power and controllable reaction rate is desired to maximize the effectiveness of matrix stimulation treatments for oil and gas wells. Hydrochloric acid (HCl) has high dissolving power, however, the reaction rate with carbonate rock is uncontrollable and can cause face dissolution. Organic acids have low dissolving power and controllable reaction rate. The objective of this paper was to compare the effectiveness of three low viscosity retarded acid recipes with dissolving powers of 15 wt% and &gt;20 wt% HCl equivalent.
The examined acid recipes were 15/28 wt% emulsified acids, retarded acid recipes #1, #2 and #3, and 15/26 wt% HCl. The emulsified acids were at 30:70 ratio of diesel to acid. The retarded acid recipes were prepared at different dissolving power. Retarded acid recipe #3 was equivalent to 15 wt% HCl while retarded acid recipes #1 and #2 were equivalent to &gt;20 wt% HCl.
The calcite disc dissolution rate with retarded acids #1 and #2 was significantly lower than 26 wt% HCl and comparable to 15 wt% HCl at 75°F. The solubility of calcite discs in the retarded acid recipe #3 showed acid retardation higher than retarded acid recipes #1 and #2. The corrosion rate of retarded acid recipes #1 and #2 were 0.003-0.015 lb/ft2 at 250°F and 6 hrs, lower than both examined 26-28 wt% HCl and emulsified acids. The pitting indices of retarded acid recipes #1, #2, and #3 were 4, 2, and 1 respectively at 300°F. The pore volumes to breakthrough (PVBT) of retarded acid recipes #1 and #2 were slightly higher than retarded acid recipes #3 at 200°F. The PVBT values for 15 wt% and 28 wt% emulsified acid was comparable to retarded acid recipes #1, #2, and #3, confirming their retardation was effective.
Workflow for Shaly-Sand Reservoir Model Calibration by Integrating Multi-Scale Data
Authors: Sajjad Farasdaq , Chandra Steven , Ivan Patrick , Wirawan Alvin , Suganda Wingky , Vico Hendro 
Published: October 2021

Abstract
The calibration of shaly-sand reservoir is challenging since the nature of geological complexity of the reservoir. This complex structure involves multiple scales that should be acknowledged during geologic and reservoir modeling activities. This paper is intended to show multi-scale response of shaly-sand reservoir, by integrating well, sector, and reservoir data. Reservvoir modeling is used as a tool to understand the concept and behaviour of shaly sand reservoir under multiple scenarios of shale geological setting and shale configuration.
The research is based on day-to-day findings in PHE ONWJ working area where drilling activities often encounter zones with very low water saturation or high pressure, even though the infill drilling is performed nearby depleted zones. This work demonstrates the needs of multiscale integration to analyze shaly-sand reservoir response. The geology of shaly-sand reservoir indicates "compartment" behavior. The interbedded shale layers disconnect the continuity of several layers. The global scale data, e.g. average reservoir pressure, cannot accurately capture the local responses and discontinuities. Therefore, huge amount of oil reserves becomes undetected and undeveloped.
Reservoir characterization based on Field X in PHE ONWJ area is used as a benchmark in modeling a generic reservoir model. The model utilizes several shale configuration and shale characteristics in order to mimic shaly sand reservoir behavior during a single primary production cycle. Whilst general production resultsis not the main concern of the current publication, The main goal of the publication is to observe pressure behaviour after several years of primary production.
The research provides a new insight on how field development plan should be prepared accordingly should there be a conviction of shaly sand reservoir from test data. Developing shaly sand reservoir should require multiple plans for higher number of infill well as well as its placement and economic aspects.
Novel Drill Bit Analysis to Delay and Mitigate Fixed Cutter Thermal Damage
Authors: Roberts Sion Llywelyn , Bailey Michael James , Babaie Aghdam Afshin , Suleiman Ahmed , Fathy Ahmed 
Published: October 2021

Abstract
As oil and gas wells become deeper, drilling longer intervals is becoming a major milestone for drill bit companies, as the process comes with a variety of challenges affecting the durability of drill bits. Among the major challenges are thermal and impact damage in polycrystalline diamond compact (PDC) cutters, which can significantly affect the performance and longevity of a drill bit. While cutter technology development remains an important arena to address said challenges, there exists a need to also address these through the design process. This paper presents the development and deployment of a new drill bit analysis method that addresses thermal damage by optimizing the design, which has been field validated across the globe.
The analysis involves estimating the thermal input load and the available cooling rate for every cutter on a drill bit during drilling conditions. The data is then used to optimize and apply changes to the design. The analysis considers all the critical and relevant operational parameters to calculate these indices. The outcome of the so-called thermal index analysis enables the design team to make informed decisions to improve the design of the drill bit and to minimize the extent of thermal damage in cutters.
The improvements made in the design include changes in cutting structure to affect cutting forces and, eventually, the thermal input load during the drilling process. This stage in practice can bring down the temperature of the cutting edge by 20%, as calculated analytically. Another major change that can affect the results is hydraulic design of the bit, which includes the location of the nozzles as well as their orientation and size. In test cases, the cooling rate improved by 50% while keeping the same flow rate though the bit.
Several field trials have validated the correlation of thermal index analysis to drill bit dulls. This analysis is now in the field evaluation and testing phase, where it is being used during the design process to improve bits with thermal damage. The field-testing phase has been primarily conducted in thermally challenging applications across the Middle East, North Africa region, and in West Texas.
Short Term Injection Re-Distribution STIR: Real-Time Waterflood Optimization Technique Using Advanced Data Analytics
Authors: Modi Gaurav , Ujjwal Manu , Simha Srungeer 
Published: October 2021

Abstract
Short Term Injection Re-distribution (STIR) is a python based real-time WaterFlood optimization technique for brownfield assets that uses advanced data analytics. The objective of this technique is to generate recommendations for injection water re-distribution to maximize oil production at the facility level. Even though this is a data driven technique, it is tightly bounded by Petroleum Engineering principles such as material balance etc. The workflow integrates and analyse short term data (last 3-6 months) at reservoir, wells and facility level.
STIR workflow is divided into three modules:
Injector-producer connectivity Injector efficiency Injection water optimization
First module uses four major data types to estimate the connectivity between each injector-producer pair in the reservoir:
Producers data (pressure, WC, GOR, salinity) Faults presence Subsurface distance Perforation similarity – layers and kh
Second module uses connectivity and watercut data to establish the injector efficiency. Higher efficiency injectors contribute most to production while poor efficiency injectors contribute to water recycling.
Third module has a mathematical optimizer to maximize the oil production by re-distributing the injection water amongst injectors while honoring the constraints at each node (well, facility etc.) of the production system.
The STIR workflow has been applied to 6 reservoirs across different assets and an annual increase of 3-7% in oil production is predicted. Each recommendation is verified using an independent source of data and hence, the generated recommendations align very well with the reservoir understanding. The benefits of this technique can be seen in 3-6 months of implementation in terms of increased oil production and better support (pressure increase) to low watercut producers. The inherent flexibility in the workflow allows for easy replication in any Waterflooded Reservoir and works best when the injector well count in the reservoir is relatively high. Geological features are well represented in the workflow which is one of the unique functionalities of this technique. This method also generates producers bean-up and injector stimulation candidates opportunities.
This low cost (no CAPEX) technique offers the advantages of conventional petroleum engineering techniques and Data driven approach. This technique provides a great alternative for WaterFlood management in brownfield where performing a reliable conventional analysis is challenging or at times impossible. STIR can be implemented in a reservoir from scratch in 3-6 weeks timeframe.
A New Method of Carbonate Matrix Stimulation Modelling and Optimisation Using Field Experimental Data for Acid Efficiency Calibration and Case Studies in Kazakhstan
Authors: Kalabayev Ruslan , Abdrazakov Dmitriy , Chuprakov Dmitry 
Published: October 2021

Abstract
Successful carbonate matrix acidizing treatments require addressing pay rock mineralogy, produced fluid flow profile, selection of the best stimulation fluids, and correct placement of these fluids. A unique method of acid and diverter fluid efficiency calibration using field experimental data for treatment modelling and optimization has been implemented successfully in several mid-temperature reservoirs, including giant oil fields in Kazakhstan. Application of the technique led to positive results.
Matrix stimulation is selected as the primary method for raising production from many carbonate reservoirs in the region because of the reservoir features. Coreflood testing conducted with candidate acid systems for selection and optimization of treatment fluid formulations and design schedules did not always lead to the desired post-stimulation skin levels, zone coverage, and production results. Hence, large-scale calibration of the acid parameters to the actual reservoir conditions was attempted. Treatment modelling in an advanced matrix acidizing software considered calibration factors derived from field tests. Thereafter, the optimized designs were implemented in the same reservoirs to improve the incremental production.
Whenever possible, coreflood testing was carried out as the first step to determine the pore-volume to breakthrough parameters for the candidate acid systems. As the second step, these laboratory-derived data were used for modelling of the offset well stimulation design. Third, the actual treatment downhole pressure was matched with the simulated pressure by means of acid efficiency calibration in the matrix stimulation software. These calibrated parameters were then used for simulation of the following treatments in the same formation in attempt to model the expected reservoir placement and zone coverage more accurately and realistically to maximize the treatment effect. Post-stimulation fluid flow profile surveys have validated the optimized models and applicability of the methodology for improving incremental well productivity in the subject reservoirs.
The stimulation approach uses a unique technique of acid efficiency calibration using field experimental data. It requires good knowledge of reservoir lithology and permeability and porosity profiles in the target zones. The initial skin is calibrated using pretreatment production data. Thereafter, acid efficiency is calibrated based on matching the actual stimulation job pressures.
Successful Wellbore Pressure Management Using Intelligent MPD and Continuous Circulation System on an HPHT Well in Vietnam
Authors: Ta Quoc Bao , Dalgit Singh Harpreet Kaur , Nguyen Le Quang Tuan , Nguyen Van Dien , Sammat Essam 
Published: October 2021

Abstract
A managed pressure drilling (MPD) and early influx detection system is gaining worldwide acceptance as an enabling technology for drilling wells with challenges that can lead to tremendous nonproductive time (NPT), significant unplanned costs, and increased risk exposure. MPD counteracts the high cost of these wells by delivering significant savings when eliminating fluid losses or well control events that cause NPT. MPD technology has proven that is used to not only reduce NPT but also enable access to reserves previously considered un-drillable. In this case history, MPD helped to reach reserves that could not be reached in the first well.
Client planned to drill the well A, which is its second offshore exploration well. Early on in 2019, the campaign encountered significant problems because of high temperatures and a narrow pore-pressure/fracture-pressure (PP/FP) gradient window. Additionally, using conventional drilling methods in offset wells led to problems relating to kicks, loss scenarios, and stuck pipe. Before drilling the second exploration well, the relevant parties considered that the first well-presented multiple drilling issues, and they drew from past success. The latter job had ended with reaching all the well targets despite high-pressure/high-temperature (HP/HT) conditions using a continuous circulating device in conjunction with an MPD system. Therefore, this combination of technologies was chosen to drill the well A.
The operator used the MPD system, from the start when drilling the 14 3/4-in × 16-in. hole section to the end when drilling the 8 1/2-in. hole section, in offshore Vietnam. Applying MPD technology on this well resulted in many benefits, including the main benefit of always controlling the bottomhole pressure through the challenging zones. MPD also helped to maintain the equivalent circulating destiny (ECD) and equivalent static density (ESD) during drilling, connections, and a logging operation to mitigate the risk of any gas breaking out at the surface and to drill the well to the desired target depth.
This paper focuses on using MPD technology in conjunction with the continuous circulation system, in offshore Vietnam. It goes into detail by describing the experience and providing some of the lessons learned.
An Application of Probabilistic Risk Assessment PRA Methodology in the Optimization of CO2 Injection Well Locations for CO2 Storage Development Plan, Offshore Malaysia
Authors: Widyanita Ana , Cai Zhong , Abdul Hamid Mohd Khaidhir , Jones Ernest A 
Published: October 2021

Abstract
A depleted gas field in the Sarawak basin, offshore Malaysia, was selected as a candidate geological site for CO2 storage. The selection and design for the CO2 injection well locations are an important decision making in the business planning, which involved a complicated risk assessment system covering subsurface and surface integration. The objective in this paper is to apply the probabilistic risk assessment method in the optimization of CO2 injection well locations for the CO2 storage development plan.
Risk comes from uncertainty, so the workflow with probabilistic risk assessment (PRA) methodology includes: 1) the risk identification and sensitivity analysis: the definition of uncertainty elements; 2) the risk analysis: the uncertainty ranges and distributions; and 3) Risk evaluation: including the individual element and composite risk evaluation. Similar to risk matrix method, two parameters used: 1) the likelihood (Pi) of occurrence of each consequence, expressed by the percentile of a threshold; and 2) the severity magnitude (Ii) of the possible adverse consequences, expressed by the coefficient of variation. The total risk is the sum of the products of Pi and Ii, displayed on the risk map.
The workflow and methodology were applied in a depleted gas reservoir for CO2 storage. The main elements identified for uncertainty analysis include: 1) structural model including the top of reservoir depth and internal reservoir zonation; 2) reservoir parameters based on porosity and permeability; 3) fluid contacts. Combing all possible cases for each element, a number of scenarios of reservoir models were constructed, which are the foundation of risk evaluation.
Risk score, expressed by probability, was calculated by all elements, generating a composite risk probability map, where there are different risk levels at different locations. Combining with engineering constraints, the CO2 injection well locations were selected by optimization, avoiding the area with high risk.
Machine Learning Application to Estimate Missing Rock Mechanical Logs and Reduce Uncertainty While Drilling
Authors: Negara Ardiansyah , Magana-Mora Arturo , Khan Khaqan , Vossen Johannes , Zhan Guodong David , Otalvora William Contreras , Bomidi John 
Published: October 2021

Abstract
This study presents a data-driven approach using machine learning algorithms to provide predicted analogues in the absence of acoustic logs, especially while drilling. Acoustic logs are commonly used to derive rock mechanical properties; however, these data are not always available. Well logging data (wireline/logging while drilling - LWD), such as gamma ray, density, neutron porosity, and resistivity, are used as input parameters to develop the data-driven rock mechanical models. In addition to the logging data, real-time drilling data (i.e., weight-on-bit, rotation speed, torque, rate of penetration, flowrate, and standpipe pressure) are used to derive the model. In the data preprocessing stage, we labeled drilling and well logging data based on formation tops in the drilling plan and performed data cleansing to remove outliers. A set of field data from different wells across the same formation is used to build and train the predictive models. We computed feature importance to rank the data based on the relevance to predict acoustic logs and applied feature selection techniques to remove redundant features that may unnecessarily require a more complex model. An additional feature, mechanical specific energy, is also generated from drilling real-time data to improve the prediction accuracy. A number of scenarios showing a comparison of different predictive models were studied, and the results demonstrated that adding drilling data and/or feature engineering into the model could improve the accuracy of the models.