bluuebunny/crossref_metadata_2025_split huggingface dataset:
Case Studies for the Successful Deployment of Wells Augmented Stuck Pipe Indicator in Wells Real Time Centre
Authors: Meor Hashim Meor M. , Yusoff M. Hazwan , Arriffin M. Faris , Mohamad Azlan , Tengku Bidin Tengku Ezharuddin , Gomes Dalila 
Published: March 2021

Abstract
The restriction or inability of the drill string to reciprocate or rotate while in the borehole is commonly known as a stuck pipe. This event is typically accompanied by constraints in drilling fluid flow, except for differential sticking. The stuck pipe can manifest based on three different mechanisms, i.e. pack-off, differential sticking, and wellbore geometry. Despite its infrequent occurrence, non-productive time (NPT) events have a massive cost impact. Nevertheless, stuck pipe incidents can be evaded with proper identification of its unique symptoms which allows an early intervention and remediation action. Over the decades, multiple analytical studies have been attempted to predict stuck pipe occurrences. The latest venture into this drilling operational challenge now utilizes Machine Learning (ML) algorithms in forecasting stuck pipe risk. An ML solution namely, Wells Augmented Stuck Pipe Indicator (WASP), is developed to tackle this specific challenge. The solution leverages on real-time drilling database and supplementary engineering design information to estimate proxy drilling parameters which provide active and impartial pattern recognition of prospective stuck pipe events. The solution is built to assist Wells Real Time Centre (WRTC) personnel in proactively providing a holistic perspective in anticipating potential anomalies and recommending remedial countermeasures before incidents happen. Several case studies are outlined to exhibit the impact of WASP in real-time drilling operation monitoring and intervention where WASP is capable to identify stuck pipe symptoms a few hours earlier and provide warnings for stuck pipe avoidance. The presented case studies were run on various live wells where restrictions are predicted stands ahead of the incidents. Warnings and alarms were generated, allowing further analysis by the personnel to verify and assess the situation before delivering a precautionary procedure to the rig site. The implementation of the WASP will reduce analysis time and provide timely prescriptive action in the proactive real-time drilling operation monitoring and intervention hub, subsequently creating value through cost containment and operational efficiency.
Improving the Directional Behavior of PDC Bits Affected by Stick-Slip: A Statistical Approach
Authors: Reboul Sébastien , Al-Mulaifi Mohammad , Al-Othman Ahmad , Shata Atef , Mohamed Ibrahim , Pelfrene Gilles , El-Genidy Ehab , Gamal Mohamed , Cuillier Bruno , Amran Fatheeni A. , Maïga Abiboulaye 
Published: March 2021

AbstractTorsional vibrations are a very common phenomenon affecting drilling operations by limiting efficiency, increasing the risk of downhole equipment failure and generating additional costs, particularly when their most severe form is encountered, the stick-slip. It is less known that torsional vibrations also strongly affect directional drilling operations reducing directional stability and tool face control. In this paper, the highly variable solicitation induced by torsional vibrations is addressed with a statistical approach. This approach, used successfully in Kuwait applications, resulted in an operational savings of 30% of the cost per foot over a panel of more than 15 runs analyzed.Steerability and directional stability is critical on directional wells, especially when using push-the-bit systems with PDC bit due to side force distributed unevenly over one bit revolution. Most of today bit design comparisons are made with an average steerability factor computed over one full revolution of the bit. The method described in this paper is going further in details and looks at the evolution of directional performance indicators within one bit revolution. With the help of a state-of-the-art 3D bit-rock interaction model, which simulates the drilling environment considering the drive system mechanism and both the drill bit and the hole being drilled as a set of 3D meshed surfaces, an accurate picture of the directional stability of the bit design is available. This approach is complemented by a statistical analysis which allows to simulate a multitude of input parameters combinations and to map the directional response of a bit design in a more robust way.Based on the results of the statistical analysis, an optimized design was selected and manufactured for a 12 ¼’-in. rotary steerable system (RSS) directional application known for having torsional vibration limitations. As revealed by the simulation results, this design was expected to exhibit a better directional stability than previous bit design iterations. This optimized design was run on RSS and positive displacement motor (PDM) assemblies and successfully drilled several wells in different fields of Kuwait operations ground. It experienced smooth and stable directional control while reducing the risk for torsional vibrations and resulted in tremendous reduction of the overall cost per foot.PDC bit selection and design process have considerably evolved in the last decade with the use of increasingly accurate simulations models. This paper presents the next step of evolution dedicated to delivering the best adapted solution to any given scenario by examining in greater detail the directional response of a drill bit.
Understanding the Effect of Rock Compressibility on CO2 Storage Capacity Estimation in a Depleted Carbonate Gas Reservoir
Authors: Chidambaram Prasanna , Tewari Raj Deo , Mohd Ali Siti Syareena , Tan Chee Phuat 
Published: March 2021

AbstractAvoiding or reducing greenhouse gases emission in the atmosphere requires extensive application of technologies and one of them is underground CO2 sequestration. Capture and storage of CO2 in depleted hydrocarbon reservoirs can reduce greenhouse gases released into the atmosphere effectively. Hydrocarbon reservoirs are considered one of the ideal geologic storage sites as they have held hydrocarbons over millions of years. Their architecture and properties are well understood due to exploration and production activities from these reservoirs. Storage projects require a large depleted hydrocarbon reservoir with good reservoir properties and are affected by several factors including voidage created by hydrocarbon production, pressure, architecture, formation permeability, aquifer influx, subsidence and compaction, and rock compressibility to name a few. Thus, realistic estimation of the storage capacity of the reservoir is a key step in the evaluation of CO2 storage plan. A good history matched simulation model incorporating the geomechanical parameters is essential to estimate storage capacity of the reservoir.Three major depleted gas reservoirs in Central Luconia field, located in offshore Sarawak, are being evaluated for future CO2 storage. Reservoir simulation is used as a tool to estimate future CO2 storage capacity of these reservoirs. Reliability of forecast from a reservoir simulation model is dependent on the quality of history match achieved. Hence it is believed that CO2 storage capacity estimates obtained from a good history matched simulation model must be reliable. However, during history matching exercise in these reservoirs, it was observed that an acceptable history match could be achieved with a range of rock compressibility values and aquifer influxes. Generally, a constant value of rock compressibility is used in conventional simulation. For example, in order to obtain an acceptable history match, with a lower compressibility, a larger aquifer influx is needed and vice versa. Interestingly, a forecast using these history match cases yield different CO2 storage capacities. A closer evaluation shows that aquifer influx has a strong impact on future CO2 storage capacity.An acceptable quality of history match can be obtained for a range of rock compressibility values when aquifer influx is adjusted along with it. Sensitivity analysis shows that future CO2 storage capacity in depleted hydrocarbon reservoir is sensitive to rock compressibility used in the simulation model. A detailed sensitivity analysis along with multiple history match scenarios is necessary to understand the range in future storage capacity when evaluating CO2 storage plan.
Convolutional Neural Networks for the Classification of the Microstructure of Tight Sandstone
Authors: Reyna Flores Ana Gabriela , Fisher Quentin , Lorinczi Piroska 
Published: March 2021

Abstract
Tight gas sandstone reservoirs vary widely in terms of rock type, depositional environment, mineralogy and petrophysical properties. For this reason, estimating their permeability is a challenge when core is not available because it is a property that cannot be measured directly from wire-line logs. The aim of this work is to create an automatic tool for rock microstructure classification as a first step for future permeability prediction.
Permeability can be estimated from porosity measured using wire-line data such as derived from density-neutron tools. However, without additional information this is highly inaccurate because porosity-permeability relationships are controlled by the microstructure of samples and permeability can vary by over five orders of magnitude. Experts can broadly estimate porosity-permeability relationships by analysing the microstructure of rocks using Scanning Electron Microscopy (SEM) or optical microscopy. Such estimates are, however, subjective and require many years of experience. A Machine Learning model for the automation of rock microstructure determination on tight gas sandstones has been built using Convolutional Neural Networks (CNNs) and trained on backscattered images from cuttings.
Current results were obtained by training the model on around 24,000 Back Scattering Electron Microscopy (BSEM) images from 25 different rock samples. The obtained model performance for the current dataset are 97% of average of both validation and test categorical accuracy. Also, loss of 0.09 and 0.089 were obtained for validation and test correspondingly. Such high accuracy and low loss indicate an overall great model performance. Other metrics and debugging techniques such Gradient-weighted Class Activation Mapping (Grad-CAM), Receiver Operator Characteristics (ROC) and Area Under the Curve (AUC) were considered for the model performance evaluation obtaining positive results. Nevertheless, this can be improved by obtaining images from new already available samples and make the model generalizes better. Current results indicate that CNNs are a powerful tool and their application over thin section images is an answer for image analysis and classification problems.
The use of this classifier removes the subjectivity of estimating porosity-permeability relationships from microstructure and can be used by non-experts. The current results also open the possibility of a data driven permeability prediction based on rock microstructure and porosity from well logs.
Application of Geological Modeling Technique Based on Seismic Frequency Division Processing and Fluids Substitution Forward Modeling in Lithologic Gas Reservoir Risk Assessment
Authors: Liu Zongbin , Lv Zuobin , Wen Jiatao , Yan Hao , Yang Zhicheng 
Published: March 2021

Abstract
JZ Gasfield is an offshore sublacustrine fan lithologic gas field located in Bohai Bay Basin, in China, with a buried depth of about 1750m. It is currently in the stage of overall development plan preparation. Two exploration wells have been drilled. They show that the gas field has characteristics of rapid lateral change in reservoir, complex distribution range and connectivity of sand bodies. In addition, the few drilling data, large well spacing and low resolution of seismic data in the evaluation stage make it extremely challenging to establish an accurate geological model of gas reservoir.
In order to solve the above problems, in this paper, an integrated geological modeling method based on seismic frequency division processing and fluid substitution forward modeling is proposed. There are four key aspects to this method. (1) Using seismic sedimentology, the lateral distribution ranges of sublacustrine fan sand bodies are described by seismic frequency division processing and interpretation technique and seismic variance attribute. (2) Based on markers of single-well, logging and seismic faceis, the average instantaneous frequency attribute is selected by optimizing the seismic attributes in the dominant frequency band, and then the distribution ranges of three subfacies including inner fan, middle fan and outer fan of the sublacustrine fan are characterized, and the fine sedimentary pattern of the sublacustrine fan is established. (3) Based on an understanding of the sedimentary pattern, fluid substitution forward modeling is carried out, and the superposition and connectivity of the sublacustrine fan sand body are described. (4) A 3D geological model of the sublacustrine fan sand body is established by using a new four-step modeling method including the concept of facies-in-facies modeling: 1) A model of the distribution of the sand body is established through a deterministic modeling method; 2) Within the sand body, according to the division results of subfacies, the distribution model of sub-facies is established; 3) A fine lithofacies model is established by combining stochastic simulation with deterministic modeling and hierarchical modeling from rough to fine under the constraint of a seismic attribute; 4) Petrophysical models are established by lithofacies control, which provide a more accurate geological model for preparation of the gas field development plan.
Based on this comprehensive study, it is concluded that there is a great possibility of reservoir disconnection between the inner fan and the middle fan, where the gas reservoir is located, and the inner fan in the updip position of the structure has the risk of no gas accumulation, and the drilling risk in the development stage is greater than the potential. Based on this geological understanding, the available reserves of the gas field are reduced by nearly 40%.
Achieving Improved Drilling Performance with Hole Cleaning Technology in Horizontal Shale Gas Wells in Sichuan Basin of China
Authors: Ji Guodong , Wang Haige , Huang Hongchun , Cui Meng , Yulong Feixue , Ma Ying , Sun Xiaofeng 
Published: March 2021

Abstract
The horizontal section length of shale gas horizontal wells in Sichuan Basin in the south-west of China generally exceeds 2000m. Cuttings are apt to accumulate and form cuttings beds along such long and curve horizontal sections due to low cuttings carrying capacity, which often results in excessive torque and drag or even stuck pipes during drilling process. According to the statistics dada inthe period of Jan. - Oct. 2019, more than 25 stuck pipe incidents and 15 rotary steering tools loss in borehole were reported due to inefficient cuttings transportation in the long horizontal wells in Sichuan Basin.
This paper studies the cuttings transportation and cuttings bed formation in horizontal wells. A prediction model for the distribution of cuttings bed was established. A monitoring and analysis software for the cuttings bed and cuttings cleaner with V-shaped spiral blades that is used to agitate the cuttings bed wasdeveloped. The software calculates the distribution and thickness of the cuttings bed according to the well trajectory, wellbore structure, drilling fluid characteristics, etc., and provides the optimal operating parameters for the removal of the cuttings bed by the rotating and reciprocating drill string. Then, the drill cuttings remover in the drill string moves to the predicted position of the drill cuttings, scrapes the drill cuttings and creates a swirling flow during the pipe rotation. The combined application of software and makeup remover can effectively solve the issue of borehole cleaning in long horizontal wells.
One of the field applications was carried out in the well Ning 209H12, a shale gas horizontal well in Sichuan Basin. The well experienced excessive torque and drag issue during the tripping of drill string of long horizontal section. Thesoftware ran based on oil well data, and it determines the placement and thickness of cuttings beds in the well and calculates the optimal operating parameters for a flow rate of about 32L/s and a speed of 100rpm to remove them. By rotatingand reciprocating the drill string with recommended operating parameters along the cuttings bed interval, the removers helped cleaning the cuttings bed efficiently and significant amount of cuttings was observed at vibration screen. After cleaning the cuttings bed interval, the trip smoothly ran to the bottom without any excessive torque and drag, and then continues to drill in cooperation with the removers to the total depth. During the well completion, there was no problem with the operation of electrical logging and production casing.
This cuttings removal technology has been used in other shale gas formations and tight gas formations where horizontal wells are widely used.
Pre-Stack Depth Migration of High Resolution Distributed Acoustic Sensing VSP
Authors: Rusmanugroho Herurisa , Jaya Makky Sandra , Zahir M Hafizal , Rahim M Faizal 
Published: March 2021

Abstract
The performance of pre-stack depth migration (PSDM) on the fiber optic, distributed acoustic sensing (DAS), vertical seismic profile (VSP) data has rarely been reported. We show the results of PSDM for the fiber optic cables, newly developed and tested at a field in Canada. We apply Kirchhoff migration, Fresnel volume migration and reverse time migration (RTM) to the walkway VSP data to obtain high resolution images of the shallow to deeper structures and provide the performance analysis of the migration methods for the DAS VSP data.
Distribution of Volcanic Rocks Porosity of Dissected Kromong Paleovolcano: Analogue of Volcanic Reservoir
Authors: Hadiyanto Imam Fikri , Hanifah Dina , Hamzah Wildan Nur 
Published: March 2021

Abstract
The potentiality of unconventional play on the volcanic reservoir was evaluated for the purpose to deliver an integrated evaluation of shallow reservoir target associated with the Northwest Java Basin (NWJB). This study provides basis discovery for further exploration and dissemination of volcanic reservoir by presenting an overview of geometric and porosity type analysis of Kromong paleo-volcano complex deposits associated with the NWJB comprehensively. Furthermore, reservoir lithofacies and pore space deployment of Kromong volcanic deposits were studied. The detailed lithofacies analysis was carried out based on field observations from several dissected- and obscure dipping-outcrops in Kromong area associated with NWJB. Following this, a set of outcrop samples were processed for megascopic description integrated with thin-section analysis by using the polarized light microscope and XRF, respectively to assess different types of reservoir pore spaces and structure. Subsequently, the physical properties-porosity measurement was conducted using ImageJ software tools to understand the potentiality of high-quality reservoir formation. The results of this study show that rocks in Kromong area associated with NWJB can be comprehensively classified into reefal limestone for carbonate deposit and into 4 categories, including volcaniclastic lava, sheeting joint lava, pyroclastic breccia, volcanic intrusion, for volcanic deposits. The proposed volcanic reservoirs of volcanic play in this study are lithologically composed of autobreccia lava, sheeting joint lava, pyroclastic breccia to andesitic- and andescitic-dikes, which comprises explosive facies and intrusive facies. Pyroclastic breccia reservoirs are primary pore-type reservoirs with devitrified micropores as main reservoir space. Whilst volcanic dikes reservoirs are mainly porous-fractured-type reservoirs with cooling fracture porosity. In conclusion, following factors that control the presence of a volcanic reservoir are lithology, lithofacies, tectonism and vulcanism. Despite worldwide discoveries of volcanic reservoirs, neither the detailed potentiality evaluation nor the postulated assumption of volcanic reservoir development in NWJB field has been examined sufficiently. This contribution offers knowledge benefits by discussing the potentiality of the Cenozoic-Quarternary volcanic reservoir of the NWJB field and providing a reference for future exploration in the petroleum industry.
Fault Detection by Using Instance Segmentation
Authors: Zhu Donglin , Li Lei , Guo Rui , Zhan Shifan 
Published: March 2021

Abstract
Fault detection is an important, but time-consuming task in seismic data interpretation. Traditionally, seismic attributes, such as coherency (Marfurt et al., 1998) and curvature (Al-Dossary et al., 2006) are used to detect faults. Recently, machine learning methods, such as convolution neural networks (CNNs) are used to detect faults, by applying various semantic segmentation algorithms to the seismic data (Wu et al., 2019). The most used algorithm is U-Net (Ronneberger et al., 2015), which can accurately and efficiently provide probability maps of faults.
However, probabilities of faults generated by semantic segmentation algorithms are not sufficient for direct recognition of fault types and reconstruction of fault surfaces. To address this problem, we propose, for the first time, a workflow to use instance segmentation algorithm to detect different fault lines. Specifically, a modified CNN (LaneNet; Neven et al., 2018) is trained using automatically generated synthetic seismic images and corresponding labels. We then test the trained CNN using both synthetic and field collected seismic data. Results indicate that the proposed workflow is accurate and effective at detecting faults.
See the Unseen through Target-Oriented Dip-Steered Seismic Resolution
Authors: Sajid Muhammad , Ghazali Ahmad Riza 
Published: March 2021

Abstract
Seismic resolution plays an important role not only in interpretation and reservoir characterization but also in seismic inversion and seismic attributes analysis. The resolution depends on several factors, including seismic frequency bandwidth, dominant frequency, and layer velocity. This paper presents a spectral resolution enhancement approach that is based on Non-stationary Differential Resolution (NSDR) that honors the local structural dip, better preserves amplitude and improves target-oriented seismic interpretation. The proposed technology is applied to both 2D and 3D seismic volumes and findings are compared with the oil industry common spectral enhancement algorithms. We demonstrate the target-oriented dip steering spectral enhancement method on two 3D field datasets and compare the resulting outcome with those obtained by conventional techniques. It is found that thinly layered subsurface geological features with steeply dipping beds are better defined, with artifacts from the conflicting dips removed.