bluuebunny/crossref_metadata_2025 huggingface dataset:
Machine Learning as Accelerating Tool in Remote Operation Realisation through Monitoring Oil and Gas Equipments and Identifying its Failure Mode
Authors: Naufal Ahmad Naufal , Samy Samy Abdelhamid , Nenisurya Nenisurya Hashim , Zaharuddin Zaharuddin Muhammad , Eddy Eddy Damsuri , Amir Amir Ali , Hilmi Mohd Hilmi , Izzatdin Izzatdin A , Jafreezal Jafreezal Jaafar , Norshakirah Norshakirah A , Emelia Emelia Akashah , Amirul Ku Amirul , Hajar Hajar M , Wahyu Ade Wahyu , Syakirah Nur Syakirah
Published: March 2021

Equipment failure, unplanned downtime operation, and environmental damage cost represent critical challenges in overall oil and gas business from well reservoir identification and drilling strategy to production and processing. Identifying and managing the risks around assets that could fail and cause redundant and expensive downtime are the core of plant reliability in oil and gas industry. In the current digital era; there is an essential need of innovative data-driven solutions to address these challenges, especially, monitoring and diagnosis of plant equipment operations, recognize equipment failure; avoid unplanned downtime; repair costs and potential environmental damage; maintaining reliable production, and identifying equipment failures. Machine learning-artificial intelligence application is being studied to develop predictive maintenance (PdM) models as innovative analytics solution based on real-data streaming to get to an elevated level of situational intelligence to guide actions and provide early warnings of impending asset failure that previously remained undetected.

This paper proposes novel machine learning predictive models based on extreme learning/support vector machines (ELM-SVM) to predict the time to failure (TTF) and when a plant equipment(s) will fail; so maintenance can be planned well ahead of time to minimize disruption. Proper visualization with deep-insights (training and validation) processes of the available mountains of historian and real-time data are carried out.

Comparative studies of ELM-SVM techniques versus the most common physical-statistical regression techniques using available rotating equipment-compressors and time-failure mode data. Results are presented and it is promising to show that the new machine learning (ELM-SVM) techniques outperforms physical-statistics techniques with reliable and high accurate predictions; which have a high impact on the future ROI of oil and gas industry.
Application of Fracture Prediction Research Based on OVT Gather in Granite Buried Hills
Authors: Sun Weizhao , Wang Zhongfan , Xia Yaliang , Chen Gang , Zhang Suhong
Published: March 2021

The space of fracture reservoir in granite buried hills varies sharply with strong heterogeneity and very difficult to predict. Conventional fracture prediction methods based on narrow-azimuth post-stack seismic data have low prediction accuracy. OVT pre-stack gather retains the information of offset and azimuth, reflects the anisotropic characteristics of fractures and can be effectively used to predict the strength and strike of fracture in granite buried hills. In this paper, based on the analysis of anisotropy of OVT gather data, according to the geological characteristics of granite fractures, optimizes the sensitive offset and azimuth OVT gather data, uses the P-wave azimuth anisotropy technique to predict the strength and strike of fractures. The prediction coincides well with the drilling results, which can provide an important guidance for the exploration and development of granite buried hill in the research area.
Maximising Asset Value through Implementation of Dynamic Well Operating Envelop
Authors: Islamov Rafael , Motaei Eghbal , Madon Bahrom , Abu Bakar Khairul Azhar , Hamdan Victor , W M Zani Luqman
Published: March 2021

Dynamic Well Operating Envelop (WOE) allows to ensure that well is maintained and operated within design limits and operated in the safe, stable and profitable way. WOE covers the Well Integrity, Reservoir constraints and Facility limitations and visualizes them on well performance chart (Hamzat et al., 2013).

Design and operating limits (such as upper and lower completion/facilities design pressures, sand failure, erosion limitations, reservoir management related limitations etc) are identified and translated into two-dimensional WOE (pressure vs. flowrate) to ensure maximum range of operating conditions that represents safe and reliable operation are covered. VLP/IPR performance curves were incorporated based on latest Validated Well Model. Optimum well operating window represents the maximum range of operating conditions within the Reservoir constraints assessed. By introducing actual Well Performance data the optimisation opportunities such as production/injection enhancement identified.

During generating the Well Operating Envelops tremendous work being done to rectify challenges such as: most static data (i.e. design and reservoir limitations) are not digitized, unreliable real-time/dynamic data flow (i.e. FTHP, Oil/Gas rates etc), disintegrated and unreliable well Models and no solid workflows for Flow assurance. As a pre-requisite the workflows being developed to make data tidy i.e.ready and right, and Well Model inputs being integrated to build updated Well Models. Successful WOE prototype is generated for natural and artificially lifted Oil and Gas wells. Optimisation opportunities being identified (i.e. flowline pressure reduction, reservoir stimulation and bean-up)

Proactive maintenance is made possible through dynamic WOE as a real time exceptional based surveillance (EBS) tool which is allowing Asset engineers to conduct the well performance monitoring, and maintain it within safe, stable and profitable window. Additionally, it allows to track all Production Enhancement jobs and seamless forecasting for new opportunities.
A Business Case for Drilling Automation: Well Cost Compression by Suppressing Downhole Tool Failure in Low Oil Market
Authors: Kusumawardhani Danaparamita
Published: March 2021

In a difficult situation where the oil market is down, reducing drilling cost is always an interesting outlook to be pursued. To do so, one should consider looking at the highest component on the drilling cost. Down-hole equipment failure and stuck pipe is avoidable during the engineering planning. It is well-known that billions of dollars have been lost and numerous Bottom-Hole Assembly (BHA) are left in the well due to such problems, related to stick-slip phenomenon. Thus, despite the low oil price, it is a new normal that some asset owners opt to invest on high-end tools to prevent stick-slip, meanwhile others are still reluctant because of its high initial costs and chose to solely focus on the technical skills to drill faster. The objective of this paper is to determine whether, and which, utilization of these automations will be an effective method to lower overall cost, between using Anti-Stick Slip Technology (AST), Surface soft-torque, Self-Adjusting PDC Bit or all three combined together.

The analysis of this project is conducted by providing conjecture in comparative method to visualize the configuration. In each case, estimated Rate of Penetration (ROP) is observed based on the recent literature of its application in similar lithology which is carbonate and interbedded shale. As the ROP increases, the overall drilling cost along with percentage of potential net saving for each case is evaluated in this study and select the most effective strategy.

The outturn suggests that despite the high initial investment, combining all technologies are economically advantaged. With the DOCC by the self-adjusting PDC bit and torque alleviation by AST to handle the rock interface in addition to BHA torque wave mitigation from surface by surface soft torque, the ROP is quantified as summation of all cases’ ROP gained as the tool complements each other. The estimated ROP of the case significantly gives high decrement of the overall cost and boosted the potential net saving. Moreover, prevention from NPT due to downhole failure and stuck pipe problem is also a contributing factor to increasing cost efficiency. Therefore, combining all the tool together is proven to be the most favorable option aside from, respectively from preferable to the less, utilizing Surface Soft Torque, Self-Adjusting PDC Bit, and AST. Although it requires high initial investment, it is worthwhile to explore the usage of automation technologies for the overall cost reduction contributes to make the case financially attractive.
Blockchain Applications in Oilfield Underground Injection Operations
Authors: Yu John P. , Lei Chengwei , Wong Duncan , Choi Jason , Cotton Jason
Published: March 2021

This research project has successfully built a Distributed Ledger Technology (DLT) based prototype using R3 Corda open source. Its purpose applies in the oil & gas underground injection control (UIC) operations for the underground aquifer protection. This DLT prototype is a permissioned network that allows oil & gas companies to create, disseminate, and trace immutable records. The network enables oil and gas companies, government regulatory agency, and all other participants to share secure records such as well information while maintaining data integrity, traceability, and security. The purpose is to create a network of trust among all the stakeholders in the UIC processes for underground aquifer protection. In this DLT network, a company submits well information, which will be digitally signed and notarized. Unauthorized changes to the information, ownership, or history will become infeasible, thanks to the underlying cryptographic technologies of DLT. The network designs so that information stored and communicated will have a high level of trustworthiness. Every participant in the network can get simultaneous access to a common view of the data. Corda platform also provides multiple functionalities, e.g., Smart contract, Vault, Identity Management, Scheduler, Notary Services, etc. Many of the functionalities automate the data processing within the DLT databases. This project's results expect to enhance public safety and improve the aquifer protection review and operational processes.

Kern County uniquely poises for a project to develop more streamlined, effective, and entirely digitized DLT-based workflows that will secure regional environmental data integrity. Water contamination is a primary concern in a region where water and petroleum play vital roles in the economy. Both industries and regulatory agencies pay close attention to environmental quality. Data integrity is a primary issue concern for those that monitor and analyze environmental data. Monitoring and forecasting based on available immutable data are imperative to mitigate complications. We have changed the manual workflow into DLT applications which takes advantage of built-in functionalities. The new review process can avoid repetitive reviews among all participants and shorten the approval time. The embedded smart contracts on the DLT network will also help automate the workflows, and therefore, will be able to help eliminate human errors and improve the turnaround time. The prototype model proves the concept of using DLT.

Our research work demonstrates DLT successfully implement into energy technology. The prototype model will further expand to all the UIC processes, such as thermal, wastewater disposal, waterflood, gas injection & disposal, etc. It is a substantial cost and time savings for all the oil and gas companies. The results of this analysis could provide the government with valuable information for significant policy and regulation decisions to further benefit the community and society.
Application of Sh S-Wave Data in Lithologic Trap Identification
Authors: Guo Jiru , Deng Zhiwen , Zhang Junyong , Tan Wei , Chen Guowen , Shi Qiao , Wang Yaling , Zhao Qian
Published: March 2021

The biogas lithologic reservoirs in Sanhu Area of the Qaidam Basin has a broad exploration prospect, however, the demands of structural implementation and reservoir prediction can hardly be met with the existing P-wave seismic data due to the thin thickness of single sandstone layers, the rapid lateral changes and the low prediction accuracy of lithologic reservoirs. The SH-wave data has a higher resolution ability in lithology prediction. I can better reflect the lateral change features of formations. Because few SH-wave logging data are available and they are in accurate in the current study area, the SH-wave velocity is estimated through petrophysical modeling and the calibration and horizon interpretation of the SH-wave data are realized combined with the P- and SH-wave matching technology. Through the inversion of S-wave data,the lithological distribution of formations are predicted in combination with the comrehensive analysis of P-wave data, which provides a favorable basis for the survey of lithologic gas reservoir in the research area and achieves a good good result. In this way,a set of reservoir prediction methods and processes suitable for the shallow biogas lithological exploration in the Sanhu Area have formed initially.
Integration of 3D Geological Modeling and Fault Seal Analysis for Pore Pressure Characterization of a High Pressure and High Temperature Exploration Well in Nam Con Son Basin, a Case Study Offshore Vietnam
Authors: Nguyen Son.T. T , Nguyen Tan.N. N , Tran Hung.N.T. N.T , Ngo Quan.A. A
Published: March 2021

The pore pressure profile of an exploration well in high pressure and high temperature (HPHT) A-Field of Nam Con Son Basin was initially predicted along the wellpath in tandem with the analogy to an offset well to design a drilling program of penetrating the unreachable sedimentary formation. The scheme had driven mud weight to encounter the pressure ramp but resulted in underbalance and influx into the wellbore that incurred downtime for well control. Subsequently, formation pressure measurement conceded the substantial disparity over the offset well so the post-drill study was conducted towards with 3D geological modeling and fault seal analysis to gain insight into overpressure generation mechanisms of the field.

Seismic interval velocity, density, resistivity data are applied for generating the validated pore pressure profile of exploration well on both Eaton and Bowers methods with calibration on formation pressure measurement for Middle and Lower Miocene Sequences. Besides, the cutting edge 3D modeling is approached to construct a robust structural and fault framework as well as to condition and upscale ultimate shale volume, pressure gradient, and overburden stress for facies and pressure distribution. The sealing capacity of a fault is quantified in terms of the pressure acting on the fault surface that is required to be exceeded for the fault to become unstable and slip including simulations of formation juxtaposition mapping, fault clay content prediction, fault flow indicators, and transmissibility.

Upon completion of the 3D model, the fault surfaces which are mapped by shale volume could provide a detailed geometry and lithology juxtaposition analysis for the fault planes. The results of the high Shale Gouge Ratio (SGR), very low fault permeability, and relatively high fault rock thickness imply that the studied faults act as a baffle to fluid flow. However, from juxtaposition observation, the displacement broadens with depth in some parts of faults and the lateral stress increases through the sync-rift stage of Middle Miocene could be a cause of overpressure in this studied area.

The 3D pore pressure and stress regime integrated with fault seal analysis in the model are generally obtained to provide both vertical and spatial overpressure characterization and advantages for well drilling plan and reservoir production. From the drilling aspect, a fault stability study can optimize the maximum allowable mud weight to not exceed while drilling so that fault reactivation does not take place. From a depletion perspective, understanding of stress variations due to lowering reservoir pressure with time can be incorporated with fault seal analysis.
Improving Cement-to-Pipe Bonding Evaluation on Coated Casing
Authors: Lumankun Barry Albert , Adiningtyas Diyah Ayu , Azwar Cinto , Osman Ahmed , Hartanto Rudi , Tanjung Erwindo , Abdila Sayid Faisal
Published: March 2021

In the Oil and Gas industries, drilling a well in both exploration and development operations is becoming more challenging due to the reservoir location and complex reservoir system. A sophisticated high-cost well structure with complex trajectory, subsea system, or even operating in deep water is sometimes unavoidable. One of the crucial factors for a successful well construction operation is to achieve excellent well integrity by having good zonal isolation throughout the target reservoir section. This requires flawless primary cementation from cement job planning, design, and up to execution. The cement bond quality will need to be evaluated by performing the post job cement execution evaluation and wireline logging cement bond log survey.

Supported with more stringent regulations, well integrity is becoming a fundamental aspect in drilling and production operations. This brings new challenges to cementing operations and subsequent cement evaluation. Flawless primary cementation is of great importance, from the job planning, design, to the execution. Post-job cement evaluations are needed by performing Pressure Match Post-Job Analysis and Wireline Logging Cement Bond Log Survey.

Key parameters in designing optimum zonal isolation cement slurry is good understanding of the wellbore technical challenges and mitigating all geological and formation-related risks, such as narrow pressure margin, gas migration risk, etc. Light cement, complicated cement composition recipes, small cement - mud weight ratio are more common these days, supported with the developing technology in cementing. These, on the other side, would impact the cement bond evaluation.

Good cement bond is crucial to ensure good zonal isolation across the reservoir intervals. Casing external coating, applied to protect casing strings from rusts, is another aspect affecting the cement bond, especially cement-to-casing bond. A more advanced cement bond evaluation tool will be required to cope with variety of cementing conditions, to enable producing undoubted log results. Thus, helping Operator in making decisions of subsequent well operations.

This paper shows and presents different cement bond log interpretation results from four wells executed with a different method of implementations, performed in a development drilling campaign in Natuna Sea, offshore Indonesia in year 2019. The paper will focus on the 9-5/8" casing cementation, on which the cement bond evaluation became one of the main attentions.
Evaluation and Optimization of Adsorption Reduction Strategies on Chemical EOR Economics
Authors: Wartenberg Nicolas , Kerdraon Margaux , Salaun Mathieu , Brunet-Errard Lena , Fejean Christophe , Rousseau David
Published: March 2021

This paper is dedicated to the selection of the most effective way of mitigating surfactant adsorption in chemical EOR flooding. Mitigation strategies based on either water treatment or adsorption inhibitors were benchmarked for a sea water injection brine, on both performances and economics aspects. Performances in surfactant adsorption reduction were evaluated by applying salinity and/or hardness gradient strategies through dedicated water softening techniques, such as reverse osmosis or nanofiltration. Adsorption inhibitor addition, which does not require any water treatment, was also assessed and optimized for comparison. For each scenario, a suitable surfactant formulation was designed and evaluated through phase diagrams, static adsorption and diphasic coreflood experiments. Then the real benefit of surfactant adsorption reduction on the overall EOR process economics (including the costs of chemicals and water treatment) was assessed depending on the selected strategy. Sea water was considered as the injection brine for this study as it is widely used in chemical EOR process and often suffers high surfactant adsorption level. It was found that residual oil saturation after chemical flooding (SORc) dropped from 29% to 7% by applying a hardness gradient through nanofiltration process while 4% was reached with reverse osmosis. Regarding costs and footprint however, nanofiltration was found to be more advantageous. Adsorption inhibitors addition met similar performances to nanofiltration-based process (SORc=7%) and could be a valuable option depending on injected volume (pilot or small deployment) or field location (off-shore) as they do not require water treatment plant investment. Overall, this study provides useful practical insights on both performances and economics for selecting the most adapted strategy depending on the considered field case.
Formation Kinetics and Self-Preservation of CO2 Hydrates in the Presence of Carboxylated Multiwall Carbon Nanotubes
Authors: Mohamad Sabil Khalik , Nashed Omar , Lal Bhajan , Foo Khor Siak
Published: March 2021

Nanofluids are known of having the capability to increase heat and mass transfer and their suitability to be used as kinetic gas hydrate promoters have been recently investigated. They have favorable properties such as high thermal conductivity, large surface area, recyclable, ecofriendly, and relatively cheap that are favorable for kinetic gas hydrate promoters. However, the nanomaterials face challenges related to their stability in the base fluid. Therefore, it is crucial to investigate the impact of surfactant free nanofluid on hydrate formation and dissociation kinetics. In this work, COOH-MWCNT suspended in water is used to study the effect of surfactant free nanofluid on CO2 hydrates formation kinetic and stability. Kinetic study on CO2 hydrates formation as well as self-preservation are conducted in a stirred tank reactor. The kinetic experiments are carried out at 2.7 MPa and 274.15 K. The induction time, initial gas consumption rate, half-completion time t50, semi completion time t95 are measured to evaluate the effect of COOH-MWCNT. Furthermore, the dissociation rate was calculated to assess the impact of COOH-MWCNT on self-preservation at 271.15 K and atmospheric pressure. The results are compared with that of sodium dodecyl sulphate (SDS). The study of CO2 hydrates formation kinetic shows that the induction time is not affected by COOH-MWCNT. The impact of nanofluid is more pronounced during the hydrate growth. The initial formation rate is the highest at 0.01 wt% of COOH-MWCNT whereas 0.01 and 0.03 wt% shows the same and shortest t50. However, t95 found to be decreased with increasing the concentration. The effect of COOH-MWCNT is attributed to the strong functional group. Self-preservation results shows CO2 hydrates are less stable in the presence of COOH-MWCNT. The result of this work may provide significant finding that can be used to developed kinetic gas hydrate promoter based on nanofluid that work better than SDS to eliminate gas hydrate formation in oil and gas pipeline.
Mass Transport and Exchange Inside Tight Matrix-Fracture Systems During CO2 Huff-n-Puff and Flooding Processes
Authors: Wei Bing , Zhong Mengying , Tang Haoran , Wang Lele , Gao Ke , Lu Jun
Published: March 2021

The potential of CO2 injection in stimulating tight oil recovery after primary production has been extensively demonstrated previously. However, the processes of mass transport and exchange inside dual-permeability matrix-facture system driven by CO2 remain unclear. To improve our understanding and supplement the existing knowledge, three types of matrix-fracture models were designed and employed to mimic CO2 injection processes (huff-n-puff and flooding modes), named fully open fracture (FOF), partially open fracture (POF), and crossed open fracture (COF) models, respectively. CO2 huff-n-puff and flooding experiments were conducted on these three models to observe the dynamics of pressure and oil recovery factor. Core-scale models were built up by history-matching the oil recovery dynamics through modifying the relative permeability curves based on Corey correlations. The mass transport and exchange processes with the proceeding of CO2 injection were delineated. The results showed that either CO2 huff-n-puff or CO2 flooding was capable of extracting the oil from tight matrix substantially but the increase in oil recovery factor became insignificant with the increase in cycle number or injection time. The oil resided in the proximity of injector, fracture and producer were primarily recovered during CO2 flooding. In the FOF and COF models, the matrix oil near the injector and producer was mainly mobilized. As for CO2 huff-n-puff, the oil saturation of the three models was reduced uniformly throughout the cores with cycles. The high sweep efficiency of CO2 largely mobilized the oil near the injector. It can be generally concluded that injecting CO2 by huff-n-puff protocol might be more beneficial than flooding mode for unconventionals. The results of this paper can provide insights into the oil recovery dynamics and mass transport and exchange induced by CO2 injection in tight reservoirs.
Alternative Method of Assessing Optimum Number of Water Injection and Infill Wells in a Field Development Plan
Authors: Ramli M. Fitri , M. Long M. Shahrul , Pote Amol Nivrutti , Ishak Khairul Azri
Published: March 2021

This paper discusses the workflow and method of selecting optimum number of infill and injection wells based on incremental recovery. Normally, for infill wells study, a ‘creaming curve’ method is used to evaluate the optimum number of wells against incremental recovery from the field. However, in the case of determining number of infill wells together with water injection wells, a more comprehensive approach is needed. One needs to evaluate the pressure depletion rate from existing and infill wells together with the dynamic of the producer-injector pairings as well as the sweeping factor.

The paper is based on infill and water injection development plan for a brown field in Sabah basin which located in Malaysia. To maintain operatability of the field in the future, several new infill and water injection wells options are evaluated for optimum field life oil production. Unlike infill or producer-only assessment, the same ‘creaming curve’ approach for combination of infill and water injection wells is less effective as large number of simulation runs are needed to sample the combination of these wells that generate optimum oil recovery. This has proven to be challenging especially when the models are large which is normally the case for brown fields and it requires extensive computational hours.

In the first part, a modified approach bringing some pre-analytic assessment of producer-injector pairing is being used. The pairings are first ranked based on streamlines visualization, drainage tables and their respective contributions towards oil recovery. The ‘creaming curve’ is then built based on the highest contribution as well as the sequencing of the pairings. The second method mentioned in this paper is the numerical approach through multi-objective optimization using assisted history matching and uncertainty tool. With the help of optimizer, the number of simulation runs can be drastically reduced when only best combination of infills and injectors for each total number of wells are considered.

Both alternative methods will be compared with the full computational runs, sampling every single combination of wells. Finally, the optimum number of wells with the combination of infill and water injection wells are analysed based on cumulative oil recovery against the Net Present Value (NPV). This case study therefore demonstrates how alternative methods can be used to resolve the optimum number of infill and water injection wells to avoid lengthy and very large numbers of simulation runs.
Innovative Multiple-Zones Injector Completion Design in Unconsolidated Sand. A New Deployment Challenge in Highly Deviated Well in the Gulf of Thailand
Authors: Khunmek Thanudcha , Parrott Keith , Bin Rosli Ahamad Faidzal
Published: March 2021

The completion of a highly deviated well involves overcoming significant deployment challenges during the drilling operations that require precise and effective conveyance and intervention. The conventional slickline intervention is unsuitable for wells with more than 60° deviation. The operator has sought to implement efficient, reliable and cost-effective deployment methods in delivering injector well. Thus, the operator decided on the e-line tubing tractor conveyed with e-line key and an e-line stroking tool.

A tubing tractor and mechanical key and stroker were used to convey the wireline key in highly deviated wells. The key and stroker tools are latched into the sliding side doors (SSDs). They will activate open or close SSDs by down-strokes or up-strokes. In particular, the SSDs are closed when it is required to pressure up the tubing to set the packers. After the packers are set, an integrity test is conducted to confirm zonal isolation. Finally, the SSD is shifted open by the tubing tractor and a low rate injection test is performed to confirm the status of the SSD before handover the well.

The operation had successfully installed multiple zones injection completions (MZC) in a highly deviated well and complemented the new completion design for the sand control in water injection well. The e-line tubing tractor and well key/stroker tools have met all operational and budgetary expectations. The traditional intervention methods in highly deviated wells, such as coil tubing, can be costly and potentially infeasible due to a footprint constraint on the drilling rig. The completion was successfully installed without any HSSE issues and the lesson learnt was recorded for future interventions when a change of injection zones is required.

For a water injector completion design, equipment was selected based on reservoir requirements i.e. sand control, injection rates and pressure, etc. The goal was to prevent sand from flowing into the tubing when water injection is temporarily paused. To address this concern, the team designed and implemented a cost- effective Autonomous Inflow Control Device (AICD) with bypass valves equipped with SSDs for injection zone selectivity. This first well has been on injection for more than two years with no sand observed in the tubing or declines in the injection rate.

The e-line tubing tractor and well key/stroker tools enabled the success of this operations and should be an option for completions in highly deviated wells. Additionally, this is the first time an AICD with bypass valves has been installed for a water injection well in the Gulf of Thailand. The success achieved with this operation in the Nong Yao field provides operators with a new solution for dealing with the water injection in the unconsolidated reservoirs.
Pulling the Production: A New Way of Looking into Brown Field Reservoirs
Authors: Ghosh A.. , Zacharia J.. , Kumar V.. , S. Chauhan R.. , Santhosh Kumar R.. , Kumar A..
Published: March 2021

One of the major brownfields in offshore India was producing for three decades from main carbonate reservoirs of the Eocene and Oligocene age. Average production of this brownfield is approximately 11,000 barrels of oil per day (BOPD). To maintain the declining reservoir pressure, the field has been under active water injection for more than two decades. However, being a complex carbonate reservoir with high textural heterogeneity, the water-front movement is not very well understood and monitored. To increase the oil production, the operator started drilling horizontal drain-holes from the platforms and has adopted a conventional perforated and blind tubing combination as a completion strategy. However, it was found that wells were performing poorly with very high water cut.

An integrated and comprehensive petrophysical workflow was applied that used data analysis and the added value of advanced 3D acoustic data in combination with nuclear magnetic resonance (NMR) data to provide a rapid realistic solution to avoid such high watercut through optimizing the completion strategy. This led to a production gain in this offshore field, which was underperforming as per earlier predictions and expectations.

Conventional well-log based qualitative evaluation for horizontal segmentation strategy was rejected in favor of an integrated approach for lateral reservoir facies delineation. Lateral petrophysical property characterization was carried out through quick integration of NMR pore-size driven facies analysis, advanced acoustic radial profiling, anisotropy, and Stoneley analysis. Permeability profiling along the horizontal drain-hole section using NMR and acoustics provided critical insight. Those were integrated to avoid potential high permeability conduits of thief zones for water breakthrough. A rock-quality index was derived to optimize the completion strategy soon after the logging, even preceding the rig-down of the acquisition runs and lowering of the completion. Zones with higher skin, deeper formation damage, and lower rock-mechanical properties were avoided for efficient swell-packer placements. The well started producing and continued production with only 10% water cut along with 450 barrels of oil compared to an average 90% watercut and 100 barrels of oil from the other wells of the same platform, which used the older nonoptimized completion strategy. Based on the promising result for the first well, the same workflow was used for two similar wells of other two different platforms inthe same field, which also resulted in similar production with enhanced oil production and reduced water cut.

The study using the rapid integrated evaluation workflow established efficient zonal isolation of high permeability thief zones with accuracy for timely optimization of horizontal well segmentation, which assisted in pulling higher production in this brownfield by reducing unwanted water production.
The Feasibility Analysis of an Underground Natural Gas Storage Using a Depleted Offshore Gasfield
Authors: Huo Hongbo , Li Jinman , Li Zhong , Zhang Xiaocheng , He Shiming , Xu Jie , Dou Peng
Published: March 2021

Objectives/Scope

Compared with the underground nature gas storage (UNGS) onshore, the offshore UNGS is further from residential areas and industrial areas, which can shave the peak of natural gas more safely. However, the investment of offshore engineering is higher. Offshore UNGS with reusing offshore depleted gas reservoir construction can not only solves the problems of offshore engineering structure and wells abandonment but also greatly reduces the investment.

Methods, Procedures, Process

According to the experience of UNGS onshore, the following factors were considered: reservoir buried depth, working gas volume, distance from land, etc. Based on one depleted gasfield in Bohai Bay, the feasibility analysis of an UNGS was carried out, the impact of the offshore UNGS on the environment, the sealing of the underground gas trap and the integrity of the wellbore were evaluated, and the result proves that the sealing of the underground gas trap of the gas field was good. The natural gas pipeline network subsea can provide transportation for the UNGS and compatible to be transformed into the offshore UNGS. However, for one thing, the poor wellbore integrity conditions and imperfect well pattern constraint the reusing, for another, the capacity of offshore facilities need to be improved.

Results, Observations, Conclusions

According to the economic evaluation, the investment of offshore depleted gas reservoir reusing as UNGS can be reduced by 56% compared with the construction of a new onshore UNGS, and 32% compared with the offshore gas field abandon. A new idea is provided for peak shaving of natural gas, greatly reducing the investment in gas storage construction. Experience has been accumulated by the feasibility analysis of offshore depleted gas field UNGS and that has a bright future.

Novel/Additive Information

The limitation of natural conditions on project construction, contingency plans for force majeure such as sea ice, storm and earthquake, etc are necessary to be considered, and its implementation still needs the support of the government and relevant non-governmental organizations
Instrumental processes, entropies, information in quantum continual measurements
Authors: Barchielli A. , Lupieri G.
Published: March 2021

In this paper we will give a short presentation of the quantum L\'evy-Khinchin formula and of the formulation of quantum continual measurements based on stochastic differential equations, matters which we had the pleasure to work on in collaboration with Prof.\ Holevo. Then we will begin the study of various entropies and relative entropies, which seem to be promising quantities for measuring the information content of the continual measurement under consideration and for analysing its asymptotic behaviour.
Statistical estimation of a quantum operation
Authors: Fujiwara A.
Published: March 2021

This paper reviews some recent developments in quantum channel estimation theory, putting emphasis on an active interplay between noncommutative statistics and information geometry.
Broken promises and quantum algorithms
Authors: Brazier A. , Plenio M.B.
Published: March 2021

In the black-box model, problems constrained by a "promise" are the only ones that admit a quantum exponential speedup over the best classical algorithm in terms of query complexity. The most prominent example of this is the Deutsch-Jozsa algorithm. More recently, Wim van Dam put forward an algorithm for unstrucred problems (i.e., those without a promise). We consider the Deutsch-Jozsa algorithm with a less restrictive (or "broken") promise and study the transition to an unstructured problem. We compare this to the success of van Dam's algorithm. These are both compared with a standard classical sampling algorithm. The Deutsch-Jozsa algorithm remains good as the problem initially becomes less structured, but the van Dam algorithm can be adapted so as to become superior to the Deutsch-Jozsa algorithm as the promise is weakened.
Commutative version of the local Hamiltonian problem and common eigenspace problem
Authors: Bravyi S. , Vyalyi M.
Published: March 2021

We study the complexity of a problem Common Eigenspace --- verifying consistency of eigenvalue equations for composite quantum systems. The input of the problem is a family of pairwise commuting Hermitian operators H_1,\ldots,H_r on a Hilbert space (\CC^d)^{\otimes n} and a string of real numbers \lambda=(\lambda_1,\ldots,\lambda_r). The problem is to determine whether the common eigenspace specified by equalities H_a|\psi\ra=\lambda_a|\psi\ra, a=1,\ldots,r has a positive dimension. We consider two cases: (i) all operators H_a are k-local; (ii) all operators H_a are factorized. It can be easily shown that both problems belong to the class \QMA --- quantum analogue of \NP, and that some \NP-complete problems can be reduced to either (i) or (ii). A non-trivial question is whether the problems (i) or (ii) belong to \NP? We show that the answer is positive for some special values of k and d. Also we prove that the problem (ii) can be reduced to its special case, such that all operators H_a are factorized projectors and all \lambda_a=0.
Lagrangian representation for fermionic linear optics
Authors: Bravyi S.
Published: March 2021

Notions of a Gaussian state and a Gaussian linear map are generalized to the case of anticommuting (Grassmann) variables. Conditions under which a Gaussian map is trace preserving and (or) completely positive are formulated. For any Gaussian map an explicit formula relating correlation matrices of input and output states is presented. This formalism allows to develop the Lagrangian representation for fermionic linear optics (FLO). It covers both unitary operations and the single-mode projectors associated with FLO measurements. Using the Lagrangian representation we reduce a classical simulation of FLO to a computation of Gaussian integrals over Grassmann variables. Explicit formulas describing evolution of a quantum state under FLO operations are put forward.
Classical and quantum fingerprinting with shared randomness and one-sided error
Authors: Horn R.T. , Scott A.J. , Walgate J. , Cleve R. , Lvovsky A.I. , Sanders B.C.
Published: March 2021

Within the simultaneous message passing model of communication complexity, under a public-coin assumption, we derive the minimum achievable worst-case error probability of a classical fingerprinting protocol with one-sided error. We then present entanglement-assisted quantum fingerprinting protocols attaining worst-case error probabilities that breach this bound.
Measuring Theoretical Descriptors of Water Oxidation: Free Energy Differences Between Intermediates Using Time-Resolved Optical Spectroscopy
Authors: Vinogradov Ilya , Singh Suryansh , Lyle Hanna , Mandal Aritra , Rossmeisl Jan , Cuk Tanja
Published: March 2021

Theoretical descriptions differentiate catalytic activity of material surfaces for the water oxidation reaction by the stability of the reactive oxygen (O*) intermediate. The underlying conjecture is that there are several meta-stable steps of the reaction, each connected by free energy differences critically dependent on O*. Recently in-situ, time-resolved spectroscopy of the (photo)-electrochemical water oxidation reaction identified the vibrational and optical signatures of O* time-evolution. However, there has been little connection between these inherently kinetic experiments and the underlying thermodynamic parameters of the theory. Here, we discover that picosecond optical spectra of the O* population modulated by a shift in reaction equilibria defines an effective equilibrium constant (Keff) containing the relevant free-energy differences. A Langmuir isotherm as a function of electrolyte pH extracts Keff using a model titania system (SrTiO3). The results show how to obtain equilibrium constants of individual reaction steps on material surfaces, which had not been experimentally accessible previously. Further, we find that for a photo-excited reaction on a semiconductor surface tuning past a pH defined by Keff doubles the initial O* population. That the free energies of the catalytic surface are definable through a time-resolved spectroscopy, alongside the finding that the surface recollects its explicit equilibrium with the electrolyte, provides a new and critical connection between theory and experiment by which to tailor the pathway of water oxidation and other surface reactions.
Remarkable Size Effect on Photophysical and Nonlinear Optical Properties of All-Carboatomic Rings, Cyclo[18]carbon and Its Analogues
Authors: Liu Zeyu , Lu Tian , Yuan Aihua , Chen Qinxue , Yan Xiufen
Published: March 2021

Inspired by recent experimental observation of molecular morphology and theoretical predictions of multiple properties of cyclo[18]carbon, we systematically studied photophysical and nonlinear optical properties of cyclo[2N]carbons (N = 3−15) allotropes through density functional theory. This work unveils the unusual optical properties of the sp-hybridized carbon rings with different sizes. The remarkable size dependence of optical properties of these systems and its underlying natures are profoundly explored, and the relevance between aromaticity and optical properties are highlighted. The extrapolation curves fitted for energy level of frontier molecular orbitals, maximum absorption wavelength, and (hyper)polarizability of considered carbon rings are presented, which can be used to reliably predict corresponding properties for arbitrarily large rings. The findings in this study will facilitate the exploration of potential application of the cyclocarbons in the field of optical material.
Hypofractionated Versus Conventional Radiotherapy with Chemotherapy in Head and Neck Cancer: A Comparative Study
Authors: Bala Sankar R  , Srinivas V  , Sharavana Bhava B S  , Venkateshwarlu E  , Prakash Babu S
Published: March 2021

Head and neck cancers are a group of malignancies that arise from common anatomic sites which include the oral cavity, oropharynx, nasopharynx, hypopharynx, larynx, sinonasal cavities and from the salivary glands. Head and neck squamous cell carcinoma (HNSCC) is the sixth most common cancer in the world and has a five-year survival rate of less than 50%. It has high recurrence rates and metastasis. It is a Prospective Observational, and Comparative Study carried out in 30 patients of Loco-regionally advanced carcinoma of head and neck. The diagnosis of loco-regionally advanced cancers of head and neck was made following AJCC staging. The subjects were divided into two groups with 15 in each arm -Accelerated Hypo Fractionated Arm and Conventional Normal Fractionated Arm. All the patients were systematically interviewed, and clinical details of all the subjects were recorded. Among the 30 patients, the highest performance status of (83.3%) ECOG-1 was observed in both the groups when compared to ECOG-2, which is not statistically significant. Hypofractionated radiotherapy can achieve similar tumour response to conventionally fractionated radiotherapy in HNSCC, although with some increase in toxicity. However, to draw some reasonable conclusion, a study with a broader sample and longer follow-up needs to be performed.
KAJIAN ASPEK SEMANTIK ISTILAH KEAGAMAAN PADA TEKS THE CULTURAL ATLAS OF ISLAM(Studi Evaluatif Melalui Pendekatan Kritik Holistik)
Authors: Kardimin Kardimin
Published: March 2021

Today the efforts of translation of books of science and technology inÂ  IndonesiaÂ  isÂ  increasinglyÂ  necessary.Â  TheÂ  needÂ  forÂ  translation business is done in both areas was caused by several things. First as a developing country, Indonesia wants to improve its progress in the fieldÂ  ofÂ  scienceÂ  andÂ  technology.Â  Second,Â  mostÂ  ofÂ  theÂ  scienceÂ  and technology books written in foreign languages. Third, the ability of our scholars to write original work in both areas was very limited.ThisÂ  studyÂ  usesÂ  aÂ  holisticÂ  approachÂ  toÂ  criticism.Â  InÂ  criticismÂ  of holistic,Â  objectiveÂ  factorsÂ  thatÂ  wereÂ  examinedÂ  inÂ  thisÂ  studyÂ  isÂ  the book Indonesian translation "Cultural Atlas of Islam" published Mizan, Bandung aslinyaaslinya book "The Cultural Atlas of Islam written by Al-Faruqi.This research resulted in the conclusion that the translation still has some drawbacks. To overcome these weaknesses need to establish someÂ  devicesÂ  thatÂ  mustÂ  beÂ  ownedÂ  byÂ  aÂ  textÂ  translatorÂ  religious cultural nuances that can be used as a guide for translators specialized texts religious nuances. In other words that the translator in the field of religion must have very specific competencies and different from other areas of the text translator.
STUDI KRITIK TERHADAP BUKU â€œAGENDA PSIKOLOGI ISLAMIâ€
Authors: Suciati Suciati
Published: March 2021

West is always grounded in empirical reality invites a number of intriguing questions, what about the non-empirical reality. Is not the reality that there is as it says in the Qur'an that genie natural and supernatural realm exists, it is not possible to study and produce a useful theory for the benefit of the people? Or whether people recognize the truth of non-empirical or metaphysical as a scientific truth that can be accounted for? Is actually a series of questions can be summarized into the question of: How epistemology of psychology Islam as a new scientific study? A series of actions in the framework of realization of the vision described the psychology of Islam as madhhab to five wanted to put a clear identity and firm, without mixed with Western psychology in terms of concept, the study and its methodology.