bluuebunny/crossref_metadata_2025 huggingface dataset:
Spatial inequalities of COVID-19 incidence and associated socioeconomic risk factors in Portugal
Authors: Almendra Ricardo , Santana Paula , Costa Claudia
Published: December 2021

COVID-19 hit the world in a sudden and uneven way. Scientific community has provided strong evidence about socioeconomic characteristics of the territory associated with the geographical pattern of COVID-19 incidence. Still, the role played by these factors differs between study areas. Geographically Weighted Regression (GWR) models were applied to explore the spatially varying association between age-standardized COVID-19 incidence rate in 2020 and socioeconomic conditions in Portugal, at the municipality level. The spatial context was defined as a function of the number of neighbours; the bandwidth was determined through AIC. Prior, the validity of the GWR was assessed through ordinary least squares models. Border proximity, proportion of overcrowded living quarters, persons employed in manufacturing establishments and persons employed in construction establishments were found to be significant predictors. It was possible to observe that municipalities are affected differently by the same factor, and that this varying influence has identifiable geographical patterns, the role of each analysed factor varies importantly across the country. This study provides useful insights for policymakers for targeted interventions and for proper identification of risk factors.
Measuring and Analyzing the Magnetic Content of Drilling Fluid
Authors: Khalili Pouya , Saasen Arild , Khalifeh Mahmoud , Aase Bodil , Ånesbug Geir Olav
Published: December 2021

Magnetic contamination of drilling fluid can impact the accuracy of a directional survey by shielding the magnetic field. Additionally, this contamination, such as swarf or finer magnetic particles, can agglomerate on the downhole tool or BOP and cause tool failure in the worst-case scenario. Thus, it is necessary to measure the magnetic content of drilling fluid. However, there is no recommended practice in API or ISO for this purpose. A simple experimental setup and measurement system was developed that can be easily deployed in the rig site to measure the magnetic contamination of drilling fluid.

47 drilling fluid samples were collected from a multilateral production well drilled with a semi-submersible drilling rig located in one of the North Sea's fields. The magnetic content of these samples was measured using the established method, and the microstructure of the collected content was analyzed using a scanning electron microscope (SEM) and x-ray diffraction analysis (XRD).

Ditch magnets are commonly installed in the flowline on the rig to remove the swarf and finer magnetic particles, if the design is optimized. Ditch magnet measurement data of the well that the drilling fluid samples were collected from is presented. Operational details and common factors that might increase the production of the magnetic content were also investigated. By comparing the measured magnetic contamination of the drilling fluid samples and ditch magnet measurement data, it was possible to evaluate the efficiency of the ditch magnet system.
Tackling the Methane Quandary: Curbing Emissions from Control Valves
Authors: Pacini Andrea , Rossini Stefano
Published: December 2021

In the wake of Eni's strategy to curb fugitive emissions - in particular methane – an innovative control valve (Clarke Shutter Valve) has been deployed and tested in an Italian Eni facility.

This shutter type valve is capable of reducing the fugitive emissions by more than 90%, as well as greatly curbing purchase costs, thanks to an innovative design in bonnet and regulating mechanism.

In order to assess the real potentiality of the innovation, four Fisher globe valves and one Fisher V-ball were substituted with the Shutter Valves on different hydrocarbon streams of the Trecate facility (Piedmont), in particular on streams containing oil, gas and corrosive fluids.

The valves were monitored for more than a year and fugitive emissions tests have been performed to detect and estimate methane leak rates.

Since this represented a first deployment of this technology in Europe, a thorough analysis and technology validation of the valves has been performed.

A successful installation and start-up were performed in 3 days by Eni's staff at in February of 2020. The valves were fully operational after the installation and to date no issues have been reported.

In order to monitor the valves performances of flow control, continuous data collection on each valve has been implemented, and the analysis performed showed that all valves behave correctly as to Eni's standards.

A fugitive emission test that has been performed at the end of 2020 with a certified portable FID/PID analyzer displayed that no methane emissions were detected from the valves.

Lastly the one year and half long technology validation concluded that the Shutter Valves are a valid technology for curbing methane emissions from the Oil and Gas plants, and that suggested to qualify the company as Eni partner for control valves.

This deployment and field tests, as well as the technological assessment performed by Eni's professionals showed the potentiality of this new type of valves in reducing the methane emissions from the petroleum industry.

Understanding the potentiality of intrinsically carbon neutral technology is a crucial step for the mitigation of greenhouse gases emissions and towards the creation of a more environmentally friendly industry.
Optimizing Directional Drilling While Simultaneously Maximizing the Whole Life Value of the Well
Authors: Clegg John Martin
Published: December 2021

Increasingly complex wells and longer laterals present new challenges for wellbore placement and wellbore quality. There is a growing understanding of the impact of well placement and wellbore quality on the overall value of the well and on the economics of completions and production. This paper looks at how requirements have evolved and will evolve beyond simply "getting to TD" as quickly as possible and how emerging technologies can help.

There is already an undercurrent of opinion that completions and production are sometimes compromised to maximize rate of penetration, but with some controversy about the exact value and how easy it is to attribute cause. This paper reviews how directional drilling practice has evolved over 100 years, and how the wellbore quality that results from the directional drilling process can be a driver for the overall value of the well. Specifically, it draws on a number of key references to examine how tortuosity doesn't just have an influence on drilling but also how it can adversely impact completions, reliability of production equipment and even production rates. The paper proposes that we consider the whole-life value of the well as a key performance indicator as we drill. It emphasises that we must cease to focus solely on rate of penetration and the depth-time curve.

The paper shows, with examples, how modern directional drilling systems can address tortuosity and improve wellbore quality. It presents an unbiased view of the industry from an independent viewpoint, exploring how directional drilling has been partially automated over the years and examining the state of the art in current automated directional drilling systems. It proposes the need for a modern directional drilling system not just in terms of drilling parameters but also in terms of automation of geometric and, ultimately, geologic aspects of directional drilling.

The paper is intended to break down the silos that can exist between drilling, completions and production functions, and to help the industry to think about the long-term consequences of performance when specifying future directional drilling equipment.
Determining Hole Size and Washout by Running a Fluid Caliper, for Cementing Purposes
Authors: Ellison Jason Scott , Ellison Charles Ralph , Davis Mike , Bird Carl , Broglie Ryan J. , Hattenbach James , Ulate Jesse , Smith Lee
Published: December 2021

This paper describes the procedure to perform a fluid caliper and how by using fluid dynamics concepts, average hole size can accurately be determined, helping to derive the amount of hole washout and the appropriate amount of cement needed to circulate or achieve desired cement height.

This process has been successfully performed on over 40,000 Permian Basin wells in West Texas and Eastern New Mexico, as well as numerous other basins in the United States. This includes vertical, directional, and horizontal wells of varying hole sizes and depths, from surface to production hole. This paper will provide real world examples, discussion of geological formations encountered, drilling fluids used, and the ultimate benefit a fluid caliper provided each operator through the accurate estimation of cement volume for the reduction of waste and satisfaction of well design and regulatory requirements.

This paper will demonstrate that fluid calipers add to the operational efficiency of most drilling operations and should be considered a "Best Practice" for most drilling programs as their use can greatly limit the need to remediate a cement job necessitating additional downhole tool runs, wasting additional valuable rig time. Also, to be addressed are the limitations of fluid calipers including lost circulation, turbulent flow, and human error.

Cementing is an integral part of the process to ensure wellbore longevity, requiring increased attention. Field practice of pumping nut plug, dye, or other markers to estimate required volumes is outdated and inaccurate. This paper will clearly identify the reasons why the modern fluid caliper is aligned with today's heightened focus on ESG. Environmentally, fluid calipers determine the proper amount of cement to prevent waste. Regarding safety, fluid calipers help ensure the operator pumps accurate cement volumes to cover corrosive and/or productive zones to prevent unwanted annular influx, and referring to governance, fluid calipers help the operator pump adequate cement volumes to satisfy well construction regulations.
Optimizing Tubing and Liner Completion Design to Improve Gas Production from Existing Wells: Case Study for ADNOC Onshore Field Abu Dhabi, UAE
Authors: Fathalla Magdy Farouk , Al Hosani Mariam Ahmed , Mohamed Ihab Nabil , Al Bairaq Ahmed Mohamed , Kherroubi Djamal , Abdullayev Azer , Roopal Allen
Published: December 2021

An onshore gas field contains several gas wells which have low–intermittent production rates. The poor production has been attributed to liquid loading issue in the wellbore. This study will investigate the impact of optimizing the tubing and liner completion design to improve the gas production rates from the wells. Numerous sensitivity runs are carried out with varying tubing and liner dimensions, to identity optimal downhole completions design.

The study begins by identifying weak wells having severe gas production problems. Once the weak wells have been identified, wellbore schematics for those wells are studied. Simulation runs are performed with the current downhole completion design and this will be used as the base case. Several completion designs are considered to minimize the effect of liquid loading in the wells; these include reducing the tubing diameter but keeping the existing liner diameter the same, keeping the original tubing diameter the same but only reducing the liner diameter, extending the tubing to the Total Depth (TD) while keeping the original tubing diameter, and extending a reduced diameter tubing string to the TD.

The primary cause of the liquid loading seems to be the reduced velocity of the incoming gas from the reservoir as it flows through the wellbore. A simulation study was performed using the various completion designs to optimize the well completion and achieve higher gas velocities in the weak wells. The results of the study showed significant improvement in gas production rates when the tubing diameter and liner diameter were reduced, providing further evidence that increased velocity of the incoming fluids due to restricted flow led to less liquid loading.

The paper demonstrates the impact of downhole completion design on the productivity of the gas wells. The study shows that revisiting the existing completion designs and optimizing them using commercial simulators can lead to significant improvement in well production rates. It is also noted that restricting the flow near the sand face increases the velocity of the incoming fluid and reduces liquid loading in the wells.
High-Speed Wired Drill Pipe and its Corresponding Manufacture & Test Technology Research
Authors: Han Haochen , Zhang Yong , Chen Jia , Sun Qi , Fang Zhimeng , Li Hexiang , Liu Zeng , Zhang Guobin
Published: December 2021

High-speed wired drill pipe and its corresponding communication technology not only can achieve high-speed transmission rate and high-capacity, but also can realize real-time monitoring and dual-way communication in whole section, which can prevent downhole problems effectively. As a series system, the homogeneity and robustness of these wired drill pipes are crucial. This paper focuses on how to overcome the difficulty in manufacturing process of information drill pipe and complete the validation test.

In order to guarantee the quality of information drill pipe and satisfy the technological requirements of mass production, we optimize the manufacturing process and put forward reasonable test techniques. The optimizations of manufacturing process include the analysis on constant tension of pressure pipe, quantitative cutting pipe and perforation in pipe nozzle. The testing techniques includes magnetic coupling coil impedance test, high pressure test, communication performance test of both single pipe and series system. The test result can be judged and evaluated by the attenuation value of the signal attenuation test and the signal reflection waveform as well as sealing reliability.

With the help of the optimization of the manufacturing process and the application of new tooling, the quality and robustness of information drill pipe is improved obviously. Pass rate in primary assembly is increased from 70% to 92%. After the second assembly, pass rate can be increased to 99.5%. Besides, the work efficiency is greatly improved and the process requirements of mass production are satisfied. The validation test can screen out the drill pipe with poor quality and performance effectively thus to improve the reliability of the whole system. By means of the improvement of manufacturing and the validation test, the comprehensive pass rate of information drill pipes is increased from 84% to 95%. During three field tests in Jilin and Daqing Oilfield, the information drill pipes functioned well and accomplished all the test tasks successfully.

High-speed wired drill pipe can improve the downhole data transmission on a large margin. The theorical transmission rate can be up to 100 kbps, 10,000 times as much as the traditional mud impulse telemetry. The manufacturing optimization and test technology can guarantee the performance and realize downhole data highway.
Control-Oriented Modelling and Optimal Adaptive Control of Parallel Compressors
Authors: Ismail Al Zawaideh Ayman , Hassan Al Hosani Khalifa , Boiko Igor , AlQassab Abdulla , Khan Ibrahim
Published: December 2021

Compressors are widely used to transport gas offshore and onshore. Oil rigs and gas processing plants have several compressors operating either alone, in parallel or in trains. Hence, compressors must be controlled optimally to insure a high rate of production, and efficient power consumption. The aim of this paper is to provide a control algorithm to optimize the compressors operation in parallel in process industries, to minimize energy consumption in variable operating conditions. A dynamic control-oriented model of the compression system has been developed. The optimization algorithm is tested on an experimental prototype having two compressors connected in parallel. The developed optimization algorithm resulted in a better performance and a reduction of the total energy consumption compared to an equal load sharing scheme.
Geochemical Inversion Applied to Oil Samples from Lower Cretaceous Reservoirs, Southeast Abu Dhabi: Implications for Hydrocarbon Exploration
Authors: Mario Jorge Lozano , Camacho Hilario , Guevara Jose
Published: December 2021

The Middle East contains some of the most fascinating and prolific oil provinces in the world. The combination of excellent source rocks of different geologic ages, the presence of outstanding reservoirs and ubiquitous seals, optimal thermal history, and structural evolution provides an ideal recipe to produce the largest oilfields in the world. The UAE is currently estimated to hold 6% of global oil reserves, 96% of which are within Abu Dhabi. However, exploration for additional recoverable reserves is becoming more challenging. Finding hydrocarbons for the future is dependent upon a detailed understanding of the petroleum systems and subtle play types. For southeastern Abu Dhabi, several petroleum systems have been proposed to explain the oil and gas accumulations in Lower Cretaceous reservoirs. This study presents the practical application of a geochemical inversion workflow to a set of oil samples from Lower Cretaceous reservoirs collected in two exploration wells recently drilled in southeastern Abu Dhabi. The geochemical inversion workflow is based on stable isotope, biomarker, and oil composition data. Preliminary results and comparisons with previously identified oil families in the UAE suggest that the oils were generated from a carbonate-rich source rock deposited during Jurassic time. Compositional data and detailed stratigraphic and structural analyses support the possibility of multiple episodes of lateral and vertical migrations. The implications and risk associated with the timing of oil generation and trap formation are presented here to define a path forward and guide the prospecting efforts within this exciting region.
A 108km2 Compressive Sensing Processing Trial
Authors: Blymyer Dustin , Koster Klaas , Warren Graeme
Published: December 2021

Compressive sensing (CS) of seismic data is a new style of seismic acquisition whereby the data are recorded on a pseudorandom grid rather than along densely sampled lines in a conventional design. A CS design with a similar station density will generally yield better quality data at a similar cost compared to a conventional design, whereas a CS design with a lower station density will reduce costs while retaining quality. Previous authors (Mosher, 2014) have shown good results from CS surveys using proprietary methods for the design and processing. In this paper we show results obtained using commercially available services based on published algorithms (Lopez, 2016). This is a necessary requirement for adoption of CS by our industry.

This report documents the results of a 108km2 CS acquisition and processing trial. The acquisition and processing were specifically designed to establish whether CS can be used for suppression of backscattered, low velocity, high frequency surface waves. We demonstrate that CS data can be reconstructed by a commercial contractor and that the suppression of backscattered surface waves is improved by using CS receiver gathers reconstructed to a dense shot grid. We also show that CS acquisition is a reliable alternative to conventional acquisition from which high-quality subsurface images can be formed.
Utilizing Capillary Pressure Measurements and Water Saturation Logs to Determine Reservoir Quality in a Giant Middle Eastern Carbonate Field
Authors: Alramahi Bashar , Jaafar Qaed , Al-Qassab Hisham
Published: December 2021

Classifying rock facies and estimating permeability is particularly challenging in Microporous dominated carbonate rocks. Reservoir rock types with a very small porosity range could have up to two orders of magnitude permeability difference resulting in high uncertainty in facies and permeability assignment in static and dynamic models. While seismic and conventional porosity logs can guide the mapping of large scale features to define resource density, estimating permeability requires the integration of advanced logs, core measurements, production data and a general understanding of the geologic depositional setting. Core based primary drainage capillary pressure measurements, including porous plate and mercury injection, offer a valuable insight into the relation between rock quality (i.e., permeability, pore throat size) and water saturation at various capillary pressure levels.

Capillary pressure data was incorporated into a petrophysical workflow that compares current (Archie) water saturation at a particular height above free water level (i.e., capillary pressure) to the expected water saturation from core based capillary pressure measurements of various rock facies. This was then used to assign rock facies, and ultimately, estimate permeability along the entire wellbore, differentiating low quality microporous rocks from high quality grainstones with similar porosity values. The workflow first requires normalizing log based water saturations relative to structural position and proximity to the free water level to ensure that the only variable impacting current day water saturation is reservoir quality.

This paper presents a case study where this workflow was used to detect the presence of grainstone facies in a giant Middle Eastern Carbonate Field. Log based algorithms were used to compare Archie water saturation with primary drainage core based saturation height functions of different rock facies to detect the presence of grainstones and estimate their permeability. Grainstones were then mapped spatially over the field and overlaid with field wide oil production and water injection data to confirm a positive correlation between predicted reservoir quality and productivity/injectivity of the reservoir facies. Core based permeability measurements were also used to confirm predicted permeability trends along wellbores where core was acquired.

This workflow presents a novel approach in integrating core, log and dynamic production data to map high quality reservoir facies guiding future field development strategy, workover decisions, and selection of future well locations.
Addressing Corrosion Stress Cracking Issue of Magnesium Frac Plugs Used in Ultra HPHT Shale Well Development
Authors: Dunne Timothy Ryan , Yue Wenhan , Zhao Lei , Nettles Damon , Cheng Peng , Ren Jiaxiang , Liu Yu
Published: December 2021

The paper discusses the unrecognized issue of accelerated cracking and dissolution of stressed high strength dissolvable magnesium components at elevated temperature. A high strength dissolvable magnesium alloy was selected for inclusion in a frac plug designed for 125°C to 175°C service after thorough tensile, compression, and dissolution testing of the alloy. After a 125°C plug field test, the plug exhibited catastrophic, premature failure. Laboratory plug testing of two magnesium alloys for the slips replicated the failure at 140°C in tap water. Dissolution testing of coupons in a more aggressive media showed inadequate mass loss to compromise functionality. It was theorized that the passivating magnesium layer was unable to form due to the stress applied to the components with magnesium's inherent reactivity with water. Slow strain rate testing was used to study the potential mechanism causing stress corrosion cracking. Two high temperature high strength alloys, DM-1 and DM-2, were tested at 4 x 10^-6 in/in/s in 140°C tap water. DM-1 demonstrated a decrease in yield from 52.4 ksi to 33 ksi, a 37% reduction as well as a decrease in ductility from 10.9% to 0.8%, a 93% decrease. DM-2 demonstrated a decrease in yield from 59.3 ksi to 32.3 ksi, a 46% reduction as well as a decrease in ductility from 10.3% to 0.7%, a 93% decrease. A scanning electron microscope evaluation showed both materials possessed a highly developed secondary phase surrounding the grain boundaries. The development and subsequent investigation of an alternative magnesium alloy, DM-3, showed semi-continuous secondary phases and was investigated for a substitute at a component level. While the ultimate tensile strength decreased minimally, the ductility decreased by 36%. Laboratory testing of the plug in identical conditions with the DM-3 slips was still successful. It is imperative for high temperature magnesium plug material selection to ensure the alloy does not have highly interconnected secondary phases which may cause sudden failure during field operation.
The Root Cause Analysis and Successful Control of an Oilwell Blowout in the Middle East
Authors: Ashena Rahman , Ghorbani Farzad , Mubashir Muhammad , Nazari Sarem Mahdi , Iravani Amin
Published: December 2021

In 2017, a blowout and explosion occurred in a drilling oilwell in the Middle East. After drilling to the depth of 2,610 m, tripping was decided in order to change the bit. When the crew were pulling the drill string out of the hole with the drill-string being at the depth of 1332 m, blowout and explosion occurred. The well was a development well drilling almost horizontally (82 degrees inclination angle) into a highly-pressured gas-cap and oil pay-zone of the oilfield. In this work, following a brief explanation of the root causal factors of the incident, we give an account of the blowout control methods applied to put an end to the blowout. Both the top-kill method and the bottom-kill method by relief well drilling, were simultaneously implemented to control the blowout. Finally, the blowout was successfully controlled by the bottom-kill after 58 days. During top-kill operations, all equipment was cleared away and this contributed to proceeding to permanent abandonment immediately after the relief well success. Finally, the adverse effect of the blowout on the environment (HSE) was qualitatively discussed.
A Fast Calculation Method for Natural Fractures Activation Considering Stress Shadow and Study on the Law of Natural Fractures Activation State Changes
Authors: Qiao Yan , Zhang Yang , Jiang Tianhong , Zhang Guobin , Chen Qing , Shang Litao , Hou Tengfei
Published: December 2021

During hydraulic fracturing process of the Permian Basin in North America, the cluster spacing has been shortened to 3m, and stress shadow can no longer be ignored. Many scholars have studied the influence of stress shadows to optimize cluster spacing. For reservoirs with natural fractures, how to activate more natural fractures through hydraulic fracturing has become the purpose. However, few scholars have studied changes in the activation law of natural fractures under stress shadow conditions. This paper establishes stress change value around single fracture according to Sneddon formula, and calculates the maximum and minimum principal stress according to plane principal stress calculation formula. Considering attenuation of net pressure, stress field of multiple fractures is established, and influence of various factors on stress re-orientation is studied. Finally, considering attenuation of net pressure with distance, according to discriminant formulas of tension & shear activation, the proportion of natural fractures that are easily activated is calculated. By designing orthogonal experiments, the influence of different factors on the proportion of activated natural fractures was studied. The stress increase in the direction of the minimum principal stress is much greater than the increase in the direction of the maximum principal stress. The stress increases in the direction of the maximum principal stress at the tip of the hydraulic fracture. The tip position between hydraulic fractures is "neutralized" due to the superposition of shear stress. Stress-fracture angle and the in-situ stress difference are the common main influencing factors for both tensile and shear activation, but the net pressure has little effect on the tensile activation of natural fracture. The fracture spacing has little effect on the activation of natural fractures. When formulating the fracturing scheme, we should pay more attention to the net pressure rather than the fracture spacing. This article provides a fast calculation method for the activation state of natural fractures considering the stress shadow, which provides a reference index for activating more natural fractures and increasing the production of a single well.
Integrating Pore Geometrical Characteristics for Permeability Prediction of Tight Carbonates Utilizing Artificial Intelligence
Authors: Khan Mohammad Rasheed , Kalam Shams , Abbasi Asiya
Published: December 2021

Accurate permeability estimation in tight carbonates is a key reservoir characterization challenge, more pronounced with heterogeneous pore structures. Experiments on large volumes of core samples are required to precisely characterize permeability in such reservoirs which means investment of large amounts of time and capital. Therefore, it is imperative that an integrated model exists that can predict field-wide permeability for un-cored sections to optimize reservoir strategies. Various studies exist with a scope to address this challenge, however, most of them lack universality in application or do not consider important carbonate geometrical features. Accordingly, this work presents a novel correlation to determine permeability of tight carbonates as a function of carbonate pore geometry utilizing a combination of machine learning and optimization algorithms.

Primarily, a Deep Learning Neural Network (NN) is constructed and further optimized to produce a data-driven permeability predictor. Customization of the model to tight-heterogenous pore-scale features is accomplished by considering key geometrical carbonate topologies, porosity, formation resistivity, pore cementation representation, characteristic pore throat diameter, pore diameter, and grain diameter. Multiple realizations are conducted spanning from a perceptron-based model to a multi-layered neural net with varying degrees of activation and transfer functions. Next, a physical equation is derived from the optimized model to provide a stand-alone equation for permeability estimation. Validation of the proposed model is conducted by graphical and statistical error analysis of model testing on unseen dataset.

A major outcome of this study is the development of a physical mathematical equation which can be used without diving into the intricacy of artificial intelligence algorithms. To evaluate performance of the new correlation, an error metric comprising of average absolute percentage error (AAPE), root mean squared error (RMSE), and correlation coefficient (CC) was used. The proposed correlation performs with low error values and gives CC more than 0.95. A possible reason for this outcome is that the machine learning algorithms can construct relationship between various non-linear inputs (for e.g., carbonate heterogeneity) and output (permeability) parameters through its inbuilt complex interaction of transfer and activation function methodologies.
Matrix Refinement in Mass Transport Across Fracture-Matrix Interface: Application to Improved Oil Recovery in Fractured Reservoirs
Authors: Alruwayi Sarah Abdullatif , Uzun Ozan , Kazemi Hossein
Published: December 2021

In this paper, we will show that it is highly beneficial to model dual-porosity reservoirs using matrix refinement (similar to the multiple interacting continua, MINC, of Preuss, 1985) for water displacing oil. Two practical situations are considered. The first is the effect of matrix refinement on the unsteady-state pressure solution, and the second situation is modeling water-oil, Buckley-Leverett (BL) displacement in waterflooding a fracture-dominated flow domain.

The usefulness of matrix refinement will be illustrated using a three-node refinement of individual matrix blocks. Furthermore, this model was modified to account for matrix block size variability within each grid cell (in other words, statistical distribution of matrix size within each grid cell) using a discrete matrix-block-size distribution function. The paper will include two mathematical models, one unsteady-state pressure solution of the pressure diffusivity equation for use in rate transient analysis, and a second model, the Buckley-Leverett model to track saturation changes both in the reservoir fractures and within individual matrix blocks. To illustrate the effect of matrix heterogeneity on modeling results, we used three matrix bock sizes within each computation grid and one level of grid refinement for the individual matrix blocks.

A critical issue in dual-porosity modeling is that much of the fluid interactions occur at the fracture-matrix interface. Therefore, refining the matrix block helps capture a more accurate transport of the fluid in-and-out of the matrix blocks. Our numerical results indicate that the none-refined matrix models provide only a poor approximation to saturation distribution within individual matrices. In other words, the saturation distribution is numerically dispersed; that is, no matrix refinement causes unwarranted large numerical dispersion in saturation distribution. Furthermore, matrix block size-distribution is more representative of fractured reservoirs.
Rapid Reservoir Modelling: Sketch-Based Geological Modelling with Fast Flow Diagnostics
Authors: Jacquemyn Carl , Hampson Gary J. , Jackson Matthew D. , Petrovskyy Dmytro , Geiger Sebastian , Machado Silva Julio D. , Judice Sicilia , Rahman Fazilatur , Sousa Mario Costa
Published: December 2021

Rapid Reservoir Modelling (RRM) is a software tool that combines geological operators and a flow diagnostics module with sketch-based interface and modelling technology. The geological operators account for all interactions of stratigraphic surfaces and ensure that the resulting 3D models are stratigraphically valid. The geological operators allow users to sketch in any order, from oldest to youngest, from large to small, or free of any prescribed order, depending on data-driven or concept-driven uncertainty in interpretation. Flow diagnostics assessment of the sketched models enforces the link between geological interpretation and flow behaviour without using time-consuming and computationally expensive workflows. Output of RRM models includes static measures of facies architecture, flow diagnostics and model elements that can be exported to industry-standard software. A deep-water case is presented to show how assessing the impact of different scenarios at a prototyping stage allows users to make informed decisions about subsequent modelling efforts and approaches. Furthermore, RRM provides a valuable method for training or to develop geological interpretation skills, in front of an outcrop or directly on subsurface data.
Investigation of Zohr Hydraulic Flying Lead Reaction Drive Shafts
Authors: Hussein Hesham , Badran Shady
Published: December 2021

The HFLs for the Zohr Phase 1 project contains a cobra head at each end that incorporates the female couplers and the locking mechanism. Beginning in February 2020, and with the most recent incident recorded in September 2020, a total of 4 supplied HFL reaction drive shafts (RDS) failed subsea, resulting in partial separation of the HFL cobra heads from their respective fixed stabplates with a loss of hydraulic supply pressure and subsequent automatic well shut ins. HFL failures occurred on both the XT and HIPPS side of the HFLs on 3 different well sites. A further RDS tested at the laboratory from the UTA end of an HFL showed signs of microscopic cracking consistent with the failed specimens suggesting it may have had the potential to lead to a failure in the future.

The failed HFLs were retrieved and returned onshore, the HFL locking mechanism was stripped down to gain access to the failed ends of the RDS and a visual inspection was performed. The initial inspection after partial disassembly to reveal the inside of the HFL locking mechanism identified that the RDS had completely failed at a location on the threaded portion of the RDS. Surface deposits were collected from each probe surfaces and analysed using scanning electron microscopy (SEM), together with energy- dispersive X-ray (EDX). A piece 10mm long was taken from each of the four probes for quantitative chemical analysis. Standard tensile and Charpy V-notch impact and Vickers hardness surveys have been conducted.

Each of the failed probe exhibited an intergranular fracture surface morphology. This was confirmed through metallography/EBSD. No single initiation site was located on fracture surfaces, although some regions showed a mixed fractographic morphology, with some small areas of micro-void coalescence. Secondary intergranular cracking and corrosion was apparent at various locations, in each of the failed probes, including in thread roots, in samples 183 and 188, and just above the thread, in sample 052. These observations points towards an environmentally assisted cracking mechanism (i.e. stress corrosion cracking). Metallography revealed two layers within surface films, both in cracks and on the fracture surface: an inner layer, rich in nickel, sulphur and aluminium, and an outer, rich in copper and sulphur. Mechanical testing and chemical analysis revealed consistent results across the probes.

The probe material was specified as Nibron Special (CuNi14Al3/DIN 2.1504) with a size of 2inch. Would be challenging to get the full root cause of using this material for subsea applications as it is resistant to seawater. Another factor contributed allows risk of material failure which should be eliminated for all subsea industry or taken into consideration to avoid further failures.
Using Zero-Offset VSP to Identify Interbed Multiples Generators, A Case Study from South Oman
Authors: Al Badi Othman Abderhman , Al Battashi Majid Mohammed , Al Rubaiey Amani Mohammed , Al Kharusi Elias Suleiman
Published: December 2021

The presence of interbed multiples is a serious concern in surface seismic processing and interpretation. Its impact is huge especially if they are masking the desirable primary reflections such as the targeted reservoirs area. The conventional demultiple methodologies such as stacking, and deconvolution often fail to suppress all the interbed multiples. Therefore, a need for other measurement is crucial to eliminate the remaining ones (Burton and Lines, 1997).

There are several approaches, data-driven or model-driven, currently available to predict the interbed multiples. However, they require an accurate identification of the multiple generators (Lesnikov and Owus, 2011). The identification of the origin of these multiples seems to be the most effective solutions to remove them, however it is not an easy task.

The allure of Zero Offset Vertical Seismic Profiles (ZOVSPs) in having the receivers placed close to the subsurface horizons, allow both upgoing and downgoing wavefields to be recordable and separable. It's the combination of short window and long window deconvolution operators which are derived based on our knowledge of downgoing wavefield which help us to determine the multiples generators at their exact depths in the subsurface.

This paper demonstrates how Zero offset VSP successfully helped to identify the major multiples generators in one of the exploratory fields in south Oman. These generators then used as an input to demultiple technique named as Extended Interbed Multiple Prediction (XIMP) that eliminates the multiples within surface seismic. As the result of the multiple elimination, the seismic to well tie tremendously improved and the reliability of the overall horizon interpretation is enhanced.
Boosting HSE Management More Efficiently and Sustainably: How Innovation Can Bring Change in Traditional HSE Mindsets?
Authors: Yonebayashi Hideharu , Kobayashi Atsushi , Hirano Susumu , Okawara Masami , Iwata Takao
Published: December 2021

As a part of laboratory Health, Safety and Environment (HSE) management system, the working environment control is applied to eliminate various occupational hazards for workers. This control is a continuous effort in our petroleum R&D laboratory as the working environment management system. As an element in the management system, workplace inspection has been taken into the regular HSE activity. Even traditional and well established, the workplace inspection has been continuously improved and optimized from various aspect of inspection design, inspection members selection, check list, and feedback. To make the continual improving practices more practical and effective, workplace features such as laboratory specific environment and ad-hoc research programs have been incorporated into the inspection design. All findings are summarized immediately after every inspection, and subsequently which types of risks hidden in the findings and necessary corrective actions are discussed. All of them: findings, risks, and corrective measures should be swiftly shared with all employees in the workplace. A check list format has been optimized from both aspects of easier recording by inspectors and correctly feedback to responsible personnel to take right counter measures. The paper analyses a large data of workplace inspection results in recent 10 years. The analysis reveals that hazardous sources are decreasing in recent years because of maturity of HSE culture in our laboratory. A combined cycle of inspection activity and data analysis would be useful for understanding the current status of working environment control and considering further updating plan. This paper discusses a practical example of laboratory HSE management system from both of detailed and high levels. Furthermore, a potential is discussed for a future workplace inspection using artificial intelligence and deep learning. The enterprising discussion contributes employee's traditional mindset fresh.
Ageing Resistance of Bi-Layer Coating Systems for Dry Lubrication of Premium OCTG Connections
Authors: Baska Philippe , François-Heude Alexandre , Millet Cécile , Thebault Florian
Published: December 2021

The latest dope-free configuration combines an electrodeposited zinc-nickel (ZnNi) plating, which provides anti-galling and most of anticorrosion properties, and an organic topcoat which provides lubrication through its low friction coefficient. This dry lubrication constitutes an alternative to storage and running dope meanwhile it improves running performances, reduces operational costs on the yard and rig and avoids dope discharge to the environment. Since the technology is "rig-ready", it must withstand the different risks of degradation occurring along its whole lifecycle. The present study aims at assessing the robustness towards ageing along storage on yards, transportation to the rig and or service life in well conditions.

The performances of the different layers were checked stepwise, first assessing the ZnNi plating alone, and then considering the additional protection brought by thermoset topcoat. Regarding atmospheric corrosion, the characterization path involved both accelerated laboratory tests (such as the VDA 233-102 cyclic corrosion test) and outdoor exposures, under plastic protectors and after their removal, in different climates: temperate, desertic and tropical. The specimens were inspected regarding at: (i) efficiency of cathodic protection provided by the metallic coating; (ii) paint blistering, (iii) propagation of corrosion from a scribe down to substrate. Regarding rig operations, some examples of rig-return were reported and the compatibility with completion fluids, encountered in case of misrun and subsequent pull-out of the column, was checked though immersion in alkaline brines. In respect to the service in simulated well conditions, the resistance to Stress Corrosion Cracking (SCC) in brines were carried out to complete the former autoclave tests to assess resistance of carbon and stainless steel to well conditions.

Both the ZnNi plating and the bi-layer system revealed lifetimes in storage conditions ranging from 3 to more than 5 years before any sign of significant degradation such as red rust, paint blistering or disbonding. According to cyclic corrosion tests results, higher lifetimes could be even expected thanks to the additional anticorrosion protection of the topcoat. Regarding exposure to completion fluids, the bilayer coating was shown to withstand 3000h exposure with no more than scarce rust indications. These results testify of the technology robustness from storage on yards to rig operations. In the multiple service conditions in wells, it was shown that the corrosion and cracking resistance of the substrate was not deteriorated by the plating presence, but instead improved in the multiple assessed well service conditions.

The present communication updates the results of atmospheric corrosion compared to the former one [1] and it details new results after rig-return and regarding the risks of cracking.
A Journey of People Development, Processes and Tools
Authors: Gomes Jorge Salgado , Merrill Robert Clifford , Sohail Shaheena
Published: December 2021

Objective/Scope

Abu Dhabi National Oil Company (ADNOC) places a priority on People Development. The reorganisation in 2016, a changing demographic, and increased emphasis on "Emiratisation" of the workforce has only reinforced that priority. The reorganisation fused together disparate companies, each with its own competency standards. The goal of ensuring that UAE national staff are used and developed throughout the organisation, coupled with our demographics, has added to the requirement for standard set of measures and processes for capability development across the ADNOC Group.

This initiative has been implemented in phases, beginning with the creation/unification of core technical, behavioral/leadership and business competencies for all subsurface disciplines across the Group. We are now creating a learning organization to address our remaining challenges. A joint effort is required between our human capital and technical discipline leaders.

Methods, Procedures, Process

The ADNOC Competency Frameworks were created through a joint effort between subject matter experts (SME) and the People Development Team. The deployment of these frameworks was done in two main steps:Creation and verification. This was a joint effort between our Human Capital organisation and domain experts from the operating companies. This deployment also saw the creation of discipline authorities for the subsurface organisation. These "Heads of Discipline" are domain experts with a focus on skills and staff development. A "self-assessment" + "manager verification" process was used to populate the competency framework database.Data analysis. A statistical subset of the data were independently verified by SME interviews. Anomalies, and disciplines with insufficient coverage were scrubbed from the data. A number of analytical tools were used for data analysis, including "Heat Maps" for visual impact.Results, Observations and ConclusionsThe results revealed strength in the "engine room" of the organization, however, some "gaps" were identified. One gap was identified in the transitional grades between the "junior" and "operational" staff. This was consistent for all disciplines, and it is being addressed through specialized training and on-the job work assignments. Another gap was identified in some specialties, in which ADNOC depends on one or two individuals for key skillsets.As we took immediate action to address some gaps, we recognised that a longer term solution was required. This has taken the form of the ADNOC Learning Institute (ALI). The ALI is a comprehensive solution which includes strategic workforce planning, future capabilities, competency and learning frameworks. These will underpin future efforts in technical succession planning and mobility.Novel AdditionsThe ADNOC Learning Institute was crafted to meet the competing challenges of skills development, demographics and Emiratisation. The ALI demonstrates how a unified vision is required to meet future challenges.