bluuebunny/crossref_metadata_2025_split huggingface dataset:
Application of Seismic Inversion of PSTM and PSDM Data to Capture the Regional Geological Trend: An Offshore Abu Dhabi Case Study
Authors: Inoue Hiroyuki , Shimoju Ryo , Kleef Franciscus Van , Al Khamiri Ahmed Mubarak , Obara Hidenori 
Published: November 2020

Abstract
Seismic processing to PSDM is now a common approach in Abu Dhabi to improve the subsurface imaging. However due to the amount of well information in this region, it is challenging to provide additional geological understanding through seismic reservoir characterization. This paper demonstrates the impact of PSTM and PSDM processing results through various trials of deterministic seismic AI inversions to provide meaningful geological information and its pitfalls.
The upper Jurassic Formation in this study area is currently categorized as un-developed reservoir and consists of high porosity and permeability grainstone dominant carbonate within a limited areal extension, the so-called Oolite belt in this region. Aimed to improve the seismic image for this reservoir and above super-giant reservoirs, PSTM and PSDM processing were implemented. Through PSDM processing, a robust velocity model was generated to solve complex overburden geologies such as high velocity channels, strongly anisotropic shale and lateral heterogeneity of these giant-reservoirs. Here the PSTM and PSDM results are evaluated during a deterministic AI inversion step.
Due to the small number of wells penetrating this undeveloped reservoir, two low frequency models were evaluated: one log interpolation only and two using merge log interpolation with PSTM and PSDM velocities for the ultra-low frequency component, respectively. Each seismic inversion result for both PSTM/PSDM seismic with these low frequency models shows a good agreement with log calculated AI and porosity. However, the low frequency model strongly influences the result away from well locations. In view of the regional geological trend, inversion results from PSDM seismic with PSDM processing velocity shows a good match to the regional geological features such as the extension of the Oolite belt and the inner ramp to mid ramp boundary. Additionally this seismic inversion result shows local high porosity regions at the crestal area and porosity changes at the flank area. These variations could be interpreted as porosity preservation after oil migration and local fracturation in depositional environment, respectively. AI inversion results from PSTM lead to more pessimistic GRV estimates and may lead to wells placed in less productive areas during the appraisal and development phases. Additionally these results mislead regional geological interpretation and potential exploration targets.
The benefit of PSDM processing is not limited to better imaging but also produces a robust velocity model leading to an improved understanding of reservoir distribution and characteristics. Integrating regional geological knowledge and seismic inversion using PSDM velocity models will help to identify exploration targets, derisk future appraisal wells and reservoir development plans.
Smart Reservoir Management with Real-Time Monitoring in an Offshore Carbonate Digital Oil Field under Miscible Gas Injection
Authors: Javid Khalid , Bascialla Guido , Sainz Alvaro , Hossni Ali Mohamed , Ettireddi Srinivas , Kumar Anurag Atul , Gonzalez Cerrada Luis Oscar , Mohamed Mohamed Sayed , Ibrahim Alhosani Khalil , Scheed Andreas 
Published: November 2020

AbstractThis Green Field was commissioned and put on production few years ago and subsequently within a few months Miscible Hydrocarbon Gas injection was started on a Field scale. It is a modern Digital Oil Field having two artificial islands built to drill all its field development wells with advanced completions such as ICV, ICD and Permanent Downhole Gauges in all Oil Producer Wells with automated multi-phase flow metering (MPFM). This paper will describe the utilization of real-time data for better and efficient Field/Wells Monitoring along with quick and smart reservoir management decision-making & improved reservoir characterization.Real-time Dashboards (some of these were published last year, [1]) are utilized for robust screening of wells as per predefined rules and alerting Engineers for any wells, which are close to violating any of the Reservoir Management Guidelines, after QC and verification timely decisions, are made to avoid those violations. These Reservoir Management Guidelines for wells BHP & WHP are taken from Fluid Model (i.e. Equation of State) since the Field has a challenging considerable vertical compositional gradient for each of its reservoirs. The Guidelines are accordingly adjusted whenever a new verified information from PLT or PVT is available. Inter-well Gas Tracers Project implementation on Field scale is ongoing, where Tracers will be injected in all Gas Injection Wells/Strings to improve Reservoirs surveillance, Reservoirs understanding, Gas Injection Management, future wells locations and completion strategy etc.Real-time MPFM Flow Tests & Permanent Downhole Gauges Pressure data is utilized for Real-time Pressure Transient Analysis (PTA) and well shut in time for PBU is therefore optimized. Moreover, All Field/well Shut Down duration opportunities are also utilized for real-time Pressure Build-up (PBU) analysis & recording WHCIP & BHCIP surveys for Oil Producer wells and therefore considerable cost of running Memory gauges and intervention operations is saved.This paper shows examples of PTA data interpretation through real time data that improved decision-making and optimize the performance of each well. The benefits of implementing a digital oil field philosophy for improved decision making in order to maximize oil recovery in a challenging enhanced oil recovery offshore project is also discussed. Successful & Smart Reservoir Management is a result of collaborative and multiple discipline Team Work.
Novel Magnetic Resonance Data Processing Method, In Correlation with Mercury Injection Capillary Pressure Pore Throat Profile and Porosity-Permeability Property to Solely Predict the Rock Type First Pass
Authors: Susanto Maria Indriaty , Al Nuaimi Mayyada Awadh 
Published: November 2020

Abstract
This paper intends to utilise magnetic resonance (MR) data to predict the rock-type (RRT), by correlating its profile to the Mercury Injection Capillary Pressure (MICP), using a novel semi-automated method. Data presented come from Oilfield A, a reservoir highly affected by diagenesis causing reservoir properties to vary laterally. As a first step the feasibility of the method will be tested on the pilot well dataset, where its suitability will be assessed before applying the technique to the development well MR dataset. The fieldwide application in both pilot and development wells will improve the confidence of rock-type distribution.
Two methods, normalised cumulative and cumulative are attempted, correlating the inferred NMR pore volume to the inferred MICP pore throat distribution, grouped according to the rock type scheme in two reservoirs. Both NMR and MICP data are arranged in the same format. On the normalised cumulative method, feasibility is conducted on MICP data to see at which normalised cumulative frequence the rock-type shows distinct pore throat clusters, while on the cumulative method the rock-type clustering is assessed on the cumulative frequency range at the total pore throat size. A key assumption is that the NMR relaxation profile representing the pore size, is similar to the MICP pore throat profile to classify the rock-type. QC is performed on the resulting curves to ensure they honour the reservoir property trends from core. One method will be chosen on this basis, where a set of criteria will be applied to the resulting curve to generate the first pass rock-type prediction.
This paper contains the step 1 of rock-type estimation in the pilot wells and the suitability of application to the development wells. The development well application itself is currently still ongoing.
Automatic Well Correlation by Aligning Multiple Well using Deep Neural Networks
Authors: Hong Youngjun , Kang Changbeom 
Published: November 2020

AbstractThe interpretation of well logs is crucial for understanding subsurface geological formations and reservoir characterization. Among various roles of well logs in an exploration stage, constructing subsurface stratigraphic structure over target area is an important task to estimate oil and gas layer. Well logs correlation which connects multiple well logs with similar traits is commonly operated for stratigraphic surface picking. However, since a subsurface stratigraphic structure is very irregular and complex, correct well logs correlation is a time-consuming and high-cost task that is usually done by many geology experts. Recently, various studies suggest using supervised machine learning algorithms to automate well logs correlation. Most works firstly build formation matched pairwise dataset and train deep neural networks such as convolutional neural networks. However, such labeled data for supervision is cost expensive and most of them are not publicized.In this paper, we propose a simple and unsupervised method for automated well logs correlation with cutting-edge machine learning techniques. Unlike existing methods, we don`t utilize well logs paired data. Rather, we utilize well logs themselves, assuming nearby well logs would have similar characteristics at adjacent depth points. Most importantly, we introduce a time-series alignment concept to well logs correlation, which can deal with multiple well logs of different lengths. We show that our well logs alignment model is effective and can be applied to well logs in any oil and gas regions up to its simplicity.
Frac Plugs Milling Optimization in Depleted Gas Wells, from Learnings to Well Delivery Enhancement
Authors: Nunez Alvaro Javier , Sayapov Ernest , Chavez Juan Carlos , Al Hinai Adnan Saif , Al Kendi Al Muntaser , Eltorabi Yousif , Al Hatmi Hatim , Makawi Sami 
Published: November 2020

Abstract
The scope of this paper is to discuss and compare the different milling strategies of the frac plugs associated to hydraulic fracturing operations in both, vertical and horizontal gas wells, with formations depleted in Petroleum Development Oman (PDO); the main objective is to describe milling operations and the well delivery improvement by the optimization of clean out and milling strategy. The paper will show the enhancement of the milling operations and the outstanding results.
The paper will start by describing the execution of hydraulic fracturing operations in both vertical and horizontal wells, which is mainly related to plug and perf. It will also cover clean out and milling practices for frac plugs in depleted formations. Further, it will discuss the planning and design of the post frac clean outs and milling jobs based on the learnings previously captured.
Frac plugs milling operations have been successfully improved in severe depleted vertical gas wells and some horizontal wells with no severe depletion; initially the milling operation was done after all frac stages were completed in depleted wells, out of the critical path, however the experience showed that it was a lengthy and expensive process due to the severe formation losses while milling leading into a very low efficient operation impacting the frac well delivery. The subsequent step was to address the milling after every stage, during the critical path, which increases the cost of daily frac charges. With the use of an innovate downhole technology the milling strategy was changed and optimized showing outstanding results, milling frac plugs was achieved successfully at the end of the job in horizontal wells while in some previous wells the milling was done in between the stages; also for vertical depleted gas wells, fracturing stages have been combined to mill frac plugs together. The completion of the entire wells (well delivery) was achieved in a relative shorter period of time compared to previous wells; this is reflected on actual cost reduction of more than 20% of total cost/AFE
The optimization of the frac plug milling operations is a novel approach to enhance hydraulic fracturing and well delivery in depleted gas wells in PDO, this is in alignment with the continuous improvement (CI) ideas and the lean thinking across the oil and gas industry nowadays. It is easy to replicate in other gas fields expected to be depleted, which will reduce cost, Health, Safety & Environment (HSE) exposure and will help increase the recovery of hydrocarbon reserves.
Accurate and Convenient Missing Well Log Synthesis using Generative Model
Authors: Kwon Minsu , Yoo Jaeyoon , Kang Changbeom , Hong Youngjun , Jeong Hoonyoung , Yoon Sungroh 
Published: November 2020

Abstract
In the oil and gas exploration, well logs, the most convenient and economic data source, usually contain missing values due to various reasons. It is crucial to generate accurate synthetic logs for such missing intervals in terms of precise well log interpretation. In this paper, we propose a workflow of generating synthetic logs using cutting-edge machine learning techniques. Unlike existing methods, we exploit a generative model, which can deal with various missing patterns with a single model, and we combine it with a supervised model. With well log data of various regions, we show that our models accurately generate missing logs and outperforms existing supervised-only models. It is expected that our model is beneficial in the real field because of its performance and simplicity.
Geomechanics Characterization of Nahr Umr and Laffan Shales Through Anisotropic Geomechanics and Shale Stability Analysis for Drilling Optimization
Authors: Xi Guifen , Draoui Elyes Habib , Alblooshi Jamal Rashed , Al-Jaberi Salem Mubarak , Al-Badi Bader Saif , Muniz Eudes Siqueira , Guerra Julian , Donald J. Adam , Povstyanova Magdalena , Martin J. Wesley , Balliache Norka Marcano , Deenadayalu Chaitanya 
Published: November 2020

Abstract
Frequent drilling challenges for high-inclination well paths in the overburden Laffan and Nahr-Umr shales involve stuck pipe incidents and caving, leading to sidetracking in extreme cases. Advanced geomechanics studies including both an anisotropic wellbore stability model and shale stability analysis were conducted on acquired cores to better understand these problematic intervals for improving drilling efficiency and reducing costs by mitigating wellbore instability.
The study analyzed the preferential directions of deformation and failure (i.e., anisotropic) in the shales and their time-dependent behavior in reacting with drilling fluid. Shale samples were preserved to avoid changes in mechanical properties due to the high clay content and low permeability. Two overburden shale intervals were analyzed to determine strength and elastic anisotropy. Dynamic anisotropic elastic properties were obtained via ultrasonic wave propagation. Strength anisotropy was evaluated using the plane of weakness model that assumes a heterogeneous media composed of a matrix rock and plane of weakness (e.g., bedding/laminations, interface between lithotypes or laminations).
The test results showed a drop of compressive strength from 50% to 70% for samples with inclination from 38 to 62 degrees, which increases the chance of formation collapse of the laminated shales at such wellbore deviation. The anisotropic analysis proved that the stress field is higher when anisotropic properties are considered, which leads to higher propensity for failure. Shale stability tests demonstrated that most of the instabilities identified in the Laffan and Nahr-Umr formations were mechanical in nature. The optimal mud weight is strongly dependent on the well trajectory to account for the plane of weakness and strength anisotropy.
Combing data from laboratory tests with advanced sonic logs enabled a more robust evaluation of the formation anisotropy at the well scale, which improved both stress predictions and mud-weight window predictions along the well trajectory. This anisotropic well-centric model helped for determining more appropriate mud weights and salinities for upcoming directional wells.
By obtaining core samples in the shale formations, the operator was able to test and characterize the anisotropic behavior and also analyzed the time-dependent behavior. These results were combined with advanced sonic logs to better understand and mitigate wellbore instability induced from the plane of weakness.
A Rock Physics Based Time-Lapse Feasibility Workflow Calibrated to Core Measurements Which Incorporates Both Fluid Changes and Pressure Depletion
Authors: Proud Christian , Jakobsen Ask Frode , Ross Rob , McKenna Jason , Dvorkin Jack 
Published: November 2020

AbstractRock physics analysis is a useful tool in time-lapse seismic feasibility studies and can help to assess the effect of pressure and saturation changes on the elastic parameters which the seismic data is sampling and hence the probability of success of a 4D seismic survey. Calibration using velocity measurements made on dry core data at varying pressure conditions allows for forward modelling of the expected seismic response at different effective pressures as well as different hydrocarbon saturation levels. The step of forward modelling the pressure changes is performed less frequently and in a less well calibrated manner than that of changing the hydrocarbon saturation as there is often no core data analysis performed at different pressures.In this study we show that incorporating pressure effects produces non-negligible changes to the elastic properties of the reservoir rock. Changes of up to 10% and 8% to acoustic and shear impedance respectively are observed in the most prospective reservoir interval when the pressure effect is included. Such changes would be detectable by high quality 4D seismic data. The authors recommend including the pressure change data whenever possible in 4D rock physics modelling.
Salt-Tolerant Surfactant for Dilute Surfactant Flooding in High-Salinity Reservoirs: Residual Oil Stripping and Displacement Mechanism and Efficiency by Ultra-Low Interfacial Tension
Authors: Yuan Chengdong , Pu Wanfen , Varfolomeev Mikhail A. , Tan Tao , Timofeeva Anastasia A. , Sitnov Sergey A. , Mustafin Aidar Z. 
Published: November 2020

Abstract
Dilute surfactant flooding is a promising EOR method. It is more economical and easier to be controlled in reservoirs compared with microemulsion flooding where high surfactant concentration is needed. In this work, we present a salt-tolerance surfactant that can attain ultra-low interfacial tension (IFT) by a low surfactant concentration (0.2wt%) under high salinity condition. And its oil stripping and displacement mechanism and efficiency under ultra-low IFT condition were investigated.
A novel anionic–nonionic surfactant with a low concentration of 0.2 wt% was used to prepare surfactant solutions at different salinity conditions. Ultra-low IFT (10−3 mN/m) was obtained at high salinity condition. These surfactant solutions were used for oil film stripping experiments in visual oil-wet quartz cell and filtration experiments in transparent sand pack model as well as two-parallel core flooding model under heterogeneous permeability conditions to study oil stripping and displacement mechanism and efficiency by ultra-low IFT.
Oil film can be effectively stripped only under ultra-low IFT condition at high salinity condition with the occurrence of wettability reversal (from oil-wet to water-wet). Oil film is stripped in the form of oil drops by automatically shrinking. The stripping mechanism by ultra-low IFT can be attributed to the reduction of water-oil IFT, water-solid surface IFT, and wearability reversal, which thus reduces the work of adhesion. Filtration experiments showed that a high displacement efficiency (additional oil recovery is about 16-23% depending on the heterogeneity) was yielded under ultra-low IFT condition at high salinity condition in dilute surfactant flooding process. In addition, a new EOR mechanism was found that ultra-low IFT can re-mobilize the trapped oil in low-permeability layer that cannot be displaced by water flooding under heterogeneous permeability conditions without any additional conformance treatment.
This anionic–nonionic surfactant can obtain ultra-low IFT at high salinity condition at a low surfactant concentration (0.2 wt%), which can effectively strip residual oil film and re-mobilize trapped oil in low-permeability zone that cannot be mobilized by water flooding under heterogeneous permeability. The development of this salt-tolerance surfactant and finding of its EOR mechanism will improve the application of dilute surfactant flooding in those reservoirs with high salinity.
Multilateral Challenges and Solutions for Installations in the Middle East
Authors: Kelsey Matthew , Fanchin Thomas , Rondon Leonque 
Published: November 2020

Abstract
Multilateral technology can provide a higher recovery factor by achieving a longer field life supported by the cumulative production of the multiple laterals, turning otherwise unviable reservoirs into economically sound targets, keeping construction costs down and minimizing risk.
This paper will focus on TAML 5 systems that meet well integrity requirements by isolating the junction from reservoir pressure or stimulations and provide independent accessibility on both laterals during the life of the well. This capability eliminates the requirement to pull the completion should access be required to the lateral for cleaning, stimulation, zonal isolation, or data acquisition. Using this technology also leads to a reduction in the cost of well construction as well as intervention.
This paper discusses challenges faced to provide accessibility to both laterals from surface without using a re-entry deflector as well as solutions including segregated and commingled flow installations. Discussion will also cover completion designs that tie new laterals into existing production casing. Case studies will include a discussion of workover operations, isolation methods, and lateral creation systems.
In the Middle East, older TAML 4 wells have been converted to TAML 5 in order to prevent detected gas migrating into the mainbore at the junction. This conversion of a cemented junction well has enabled production to resume on the wells. This application has also been applied to the installation of new wells in the region. New and re-entry wells were completed with intelligent upper completions to enable flow control of each lateral.
The paper focuses on the challenges, solutions, and successful case studies of multilateral wells constructed in the Middle East. The paper also provides insight as to methodology for continually improving reliability of multilateral installations to maximize efficiencies.