bluuebunny/crossref_metadata_2025 huggingface dataset:
Light Weight Structure LWS Installation Using Jack up Rig
Authors: Nor Azhar Norshaiful Azril
Published: November 2020

This paper is to highlight the success offshore installation campaign of D28JT-A and D18JT-D platforms utilizing Jack-Up Rig (JUR) and the technical challenges during offshore execution. The installation work limitations and difference in installation sequence are also presented in this document. Light Weight Structure (LWS) has become one of the novel alternatives and cost-effective solutions for marginal field offshore facility in the recent years in meeting tight budget for Final Investment Decision (FID).

The basic concept of LWS is to design the topside and substructure that could be lifted by JUR for installation. Hence, a minimal facility design approach was selected for this project due to limited capability of the selected JUR. While the basic principle of load out and transportation remains the same, methodology and systems used to execute the offshore installation campaign are vary significantly. This concept has posed numerous technical and operational challenges.

PETRONAS Carigali Sdn. Bhd. (PCSB) has undertaken the development of D28JT-A and alliance with partner for D18JT-D development. Both projects are located at offshore Sarawak in Malaysia. D28JT-A and D18JT-D are wellhead platforms utilizing design one and built many concepts where both platforms were similar in design with only difference in weight. Both platforms were installed by the same JUR.

The installation work required high precision engineering and execution especially during topside lifting considering the close proximity (≪ 1 meters) between substructure and topside. Position Monitoring System and Weather Monitoring System were essential and closely monitored for safe work execution. Transportation marine vessel dynamic positioning (DP) system checks were conducted prior approaching the substructure. Both Topsides were lifted and set down within 3.25 hours. These projects had successful HSSE track record with zero LTI or incident.

It is proven that the installation of light weight structure by JUR is technically feasible and become a benchmark for future projects especially for marginal field development. Utilization of JUR for offshore platform installation significantly reduce the offshore installation cost due to JUR daily charted rate (DCR) and sharing mobilization and demobilization of installation and drilling campaigns.

This paper should be an interest for marginal field development utilizing "fit-for-purpose" design facilities.
Physics Driven AI Coreflooding Simulator for SCAL Data Analysis
Authors: Mathew Eric Sonny , Tembely Moussa , AlAmeri Waleed , W. Al-Shalabi Emad , Shaik Abdul Ravoof
Published: November 2020

Two of the most critical properties for multiphase flow in a reservoir are relative permeability (Kr) and capillary pressure (Pc). To determine these parameters, a meticulous interpretation of coreflooding and centrifuge experiments is necessary. In this work, a machine learning technique was incorporated to assist in the determination of these parameters quickly and synchronously.

A state of the art framework was developed where a large database of Kr and Pc curves were generated based on existing mathematical models. This database was used to perform thousands of coreflood simulation runs representing drainage steady state experiments. The results obtained from the corefloods including pressure drop and water saturation profile along with other conventional core analysis data were fed as features into the machine learning model. The entire data set was split into 70% for training, 15% for testing, and the remaining 15% for the model validation. The 70% of the training data teaches the model to capture fluid flow behavior inside the core. K-fold cross validation technique was also utilized to increase the accuracy of the model. The trained/tested model was thereby employed to estimate Kr and Pc curves based on available experimental results.

The values of the coefficient of determination (R2) was used to assess the accuracy and efficiency of the developed model. The respective cross plots indicate that the model is capable of making accurate predictions with error percentage less than 2% on history matching experimental data. Furthermore, the latter implies that the AI-based model is capable of determining Kr and Pc curves with less effort and better reliability as opposed to the conventional way of creating an entire simulation model. Additionally, the results include multiple options for Kr and Pc curves from which the best solution can be determined using engineering judgement. This is unlike solutions from existing commercial software, which usually provides only a single solution. The model currently focusses on the prediction of Kr and Pc curves for drainage steady state experiments; however, the work can be extended to capture the imbibition cycle as well.
CFD Simulations of Oil Viscosity and Emulsion Effects on ESP Stage Performance
Authors: Banjar Hattan , Zhu Jianjun , Zhang Hong-Quan
Published: November 2020

Oil-water emulsion effects on a seven-stage electrical submersible pump (ESP) performance are studied experimentally and numerically with computational fluid dynamics (CFD) simulation. At different oil-water fractions, temperatures, and ESP rotational speeds, the performance of the third stage was measured. The intention of this work is to validate and compare experimental data with CFD simulation results. In addition, flow structures can be visualized through the CFD simulation for oil-water emulsion flows.

Density and mass flow rate are measured using the mass flowmeter while the emulsion effective viscosity is derived from the pipe viscometer installed downstream of the ESP. CFD simulations are carried out with estimated droplet sizes of the dispersed phase for oil-water flows, and the results are compared with the experiments. For the wall roughness, a higher value is used due to the extended use of the ESP. The three-dimensional, steady-state Reynolds-Averaged Navier–Stokes (RANS) equations with standard shear stress transport (SST) turbulence model are solved in ANSYS CFX solver by employing the frozen-rotor technique. With high-quality structured hexahedral mesh grids, the simulated pressure increment is compared with corresponding experimental results.

For single-phase cases, results show considerable differences compared to experiments, which may be partially due to neglecting leakage losses in CFD simulations. When the two-phase simulation is conducted, it is confirmed that the solver takes oil and water as dispersion instead of emulsion, for which rheological behavior is not reflected. This is because the solver is based on two sets of Navier-Stokes equations for each phase. Consequently, the better approach for simulating the emulsion flow in ESPs by CFD methodology is to assume a single-phase, pseudo-homogeneous fluid with the rheology depending on the oil and water fractions and properties.
Evaluating Hole Cleaning Capability of Biodegradable Fiber-Containing Drilling Fluids in Riserless Tophole Drilling
Authors: Aoki Tatsuyoshi , Naganawa Shigemi , Abe Kazunori , Mukai Ryutaro
Published: November 2020

Fiber-containing drilling fluid enhances hole cleaning or cuttings transport efficiency without significantly affecting the rheological properties of the base fluid. Objective of this study is to evaluate the hole cleaning capability of a novel seawater-biodegradable polymer fiber-containing drilling fluid for use in riserless tophole drilling through large-scale cuttings transport experiments.

The Poly(3-HydroxyButyrate-co-3-Hydroxyhexanoate) (PHBH) is 100% bio-based and biodegradable yet resistant to heat and hydrolysis. Dispersibility of the PHBH polymer fiber in base fluids and rheological properties of the fiber-containing fluids were examined in the laboratory. Cuttings transport experiments were then conducted using the large-scale cuttings transport flow loop apparatus for several selected combinations of base fluids and fibers based on the lab test. Cuttings transport behaviors were recorded on a digital video for further image analyses.

The fibers showed good dispersibilities in base fluids with various concentrations of polyanionic cellulose (PAC) polymer and even in water. Adding fibers to base fluids increased viscosities at low shear rate ranges corresponding to 3, 6 and 100 rpm measurements of Fann Model 35 rotational viscometer without significant changes in overall rheological properties, which is expected to considerably improve cuttings transport efficiency. In addition, this positive tendency to cuttings transport efficiency was more significant in relatively low concentrations of PAC. To the video images recorded during the cuttings transport experiments, the particle image velocimetry (PIV) technique was applied to determine the cuttings transport velocities and cuttings concentrations accumulated in the annulus. Adding fibers increased cuttings transport velocities by up to about 1.5 times in vertical annulus. In near-vertical (hole inclination angles up to 30°) annulus, the cuttings were observed to flow as dunes or fluidized beds in which the cuttings re-entrainment from dunes was confirmed to be enhanced particularly at lower fluid flowrates.
Optimizing Hydrocarbons Recovery in a Complex Reservoir with Extremely Uneven and Low-Resolution Sand Distribution
Authors: Ahmed Sheraz , Waqas Ghulam , Sajid Muhammad , Bugti Jahanzeb
Published: November 2020

In the midst of current oil prices, most companies have shifted their focus on cost-constrained policies for hydrocarbon exploitation, thereby making robust subsurface description a real challenge. Developing a reservoir in such scenario is a massive problem. This study presents various engineering algorithms on such a low-resolution and uneven sandstone reservoir, to optimize the development and expected ultimate recovery - while honoring multiple challenges and limitations.

This study focuses on a newly discovered formation, in one of the oldest fields in Pakistan. The productive section of the reservoir comprises of sandstone units in beds up to 40 m thick, separated by mudstone intervals; and is interpreted to be deposited in lower progradational intervals of a delta. To date, three different depositions have been identified with two of them in hydraulic communication and one isolated with faults. Since the seismic data has limitations in its resolution; various engineering analyses were carried out, among which the variations in reservoir pressures, GWC and PVT properties played a major role in the identification of partially drained and isolated prospects.

The first two successful wells in the isolated compartment were high producers. However, sudden water production (from fractures) loaded up these wells with only 45% recovery from the compartment - very low for a weak-water drive dry gas system. The static and dynamic data set also showed the existence of more Hydrocarbons. Thus, several engineering and geological information, including the re-interpreted Seismic and simulation models, were applied to analyze the possibilities of concurrent sweet spots. Finally, after utilizing multiple algorithms & risk calculations, more wells were drilled - leading to the revelations of two more depositions in the reservoir, which were in hydraulic communication with each other but isolated with the first compartment. This added around 60% more reserves to the current mix of resources. Two more wells are now planned in the reservoir to optimize the field potential in both compartments. This will lead to an additional 23% reserves value, giving an overall EUR of ~83% from these compartments.

The main achievement of this study includes the exploitation strategy of a complicated depositional system to optimize a reservoir full of uncertainties. Since the seismic cannot be solely relied upon in such formations; this paper also illustrates the robust engineering models and detailed algorithms to ensure the development of such low-resolution reservoir without incurring major costs. This study offers an innovative approach that can be undertaken to place the wells at optimum locations, along with the utilization of each data set in a more systematic manner to access the, otherwise, undrained locations.
Challenges of Oil and Gas Mega-Projects: Claims Management Process
Authors: Robottom Luke , Tarancon Plata Raquel
Published: November 2020

One of the major challenges of oil and gas mega projects is the claims management process. This paper will discuss how claims, which arise during the lifecycle of a project, can be managed by both the contractor and by the procuring entity. This is particularly relevant to the industry with the recent Covid-19 events and its impacts.

This paper will evaluate and discuss key risks in the implementation of a project – including project cost escalations as well as time overruns and delays to completion of the project or its milestones – and the management of claims in relation thereto. This paper will also discuss how risks may be allocated where a project may be derailed. Secondary impacts will also be considered such as a compromise on quality and potential defects. Lastly, this paper will cover how formal disputes, which arise when claims cannot be adequately resolved, may be brought about and the best position the procuring entity and the contractor can put themselves in for such proceedings.

This paper shall conclude that an optimised "life cycle" approach to procurement is essential. From the beginning of the project, companies should carefully consider how risks are allocated, and from a practical perspective, what the most material risks are that are either likely to occur or could have a significant impact on the project, to ensure in particular that management of those potential risks and impact are adequately addressed in the project documents. During the life of the project there mustbe efficient contract management, it is crucial for the project management team to proactively manage claims in real time to avoid disputes. Lastly, it is key that the company is prepared for formal dispute resolution proceedings by reviewing its position regularly and keeping options open.

This paper draws on our legal expertise based on our vast experience in the field. Based on this experience, this paper applies that knowledge to what is critical in the management of claims throughout the lifecycle of the project. This will assist companies to allocate risk accordingly, mitigate and manage claims and prepare for potential formal disputes.
Smart Way for Consistent Cement Bond Evaluation and Reducing Human Bias Using Machine Learning
Authors: Voleti Deepak Kumar , Reddicharla Nagaraju , Guntupalli Suryanarayana , Reddy Rathnakar , Vanam Prabhaker Reddy , Khanji Maitha Shehab , Sumaidaa Saleh A. , Sultan Ali Mayada Ali
Published: November 2020

Cement evaluation data acquired in oil and gas wells for confirmation of zonal isolation, channeling in cement behind casing and well integrity. All available technologies for cement evaluations are primarily measurements of acoustic parameters like amplitude of first arrival, full waveform recording of refracted wave, impedance and attenuation or there a combination. Generally, operationsPetrophysicist, petroleum engineer or service providers are responsible for evaluation of cement bond logs and propose remedial jobs if required. This cement bond log interpretation is quite subjective if performed through pure visual interpretation and its accuracy depends on objective of well, work pressure and experience of interpreter. This paper talks about how ADNOC Onshore has leveraged machine learning (ML) for interpretation of various cement bond logs from several service providers.

In green fields, cement evaluation is very important in all new wells to ensure good cement quality and zonal isolation and it is also equally important in in brown fields where 1000s of wells were drilled where well integrity issues are of common occurrence. Major challenges in evaluation are inconsistency and human bias in interpretation and as a result, interpretation may vary from one interpreter to the other.

Authors have tested different ML techniques (Random Forest Classification & Neural Net) and smart way of data training. Final recommendation is to use nested models instead of single model. In this technique, input measurements and required solutions will be classified and divided into different classes, a separate ML model will be built for each class and combine all the models to get final cement evaluation and recommendations.

Final results include data quality flags, cement bond quality, zonal isolation, channeling, micro annuals, areal cement map (if analyzed field wise), anomaly maps (if analyzed data from offset wells at different times), and recommendation.

In this project, a simple easy to use user interface has been developed to browse the cement logs and use the trained ML models to predict the cement evaluations with a click of a button.

This ML based cement bond evaluation is proved to be very effective and saved 75% of efforts by operational Petrophysicists. The interpretation accuracy has been significantly improved. This method has potential to be used at rig site. These models are very cost effective with, minimum human bias, and improves consistency as well as independent of wells or type of reservoirs. These models are tested across ADNOC Onshore Wells and can be extended to any well irrespective of geographic locations.

This paper discusses machine-learning approach, evaluation of various algorithms and testing results for cement evaluation log from various service providers.
An Experimental Study to Demonstrate that Nanoparticles can Filter into Shale Formations and Improve Wellbore Stability
Authors: Zhou Nancy , Wu Yongkang , Lu Meng , Li Yucheng , Liu Fuchen , Zhang Guoping
Published: November 2020

For fields with hard and brittle shale sections that have microfractures (either preexisting in the formation or induced by drilling operations), we experienced troublesome drilling with a relatively low rate of penetration (ROP). A systematic experimental work has been implemented to discover whether nanoparticles added to drilling fluids penetrate shale formations and improve wellbore stability.

Starting with quantitative analysis of the shale rocks, we found the mineralogy and clay composition of these rocks by using X-ray diffraction (XRD). The XRD analysis shows that the shale rocks consist of mixed-layer clays and are very heterogeneous. The shale samples were then characterized by X-ray computed tomography (XCT) and scanning electron microscopy (SEM) to gain an understanding of preexisting microfractures. The XCT results show that multiple cracks are irregularly distributed inside the shale with widths between 10 to 25 μm. Smaller cracks with widths ranging from 100 to 250 nm were also observed via imaging on the shale sample surface using SEM. To answer whether adding the nanoparticles improves wellbore stability, we first designed the nanoparticle infiltration test by flowing nanoparticle dispersions through the shale assembly at an inflow pressure of around 800 kPa. After the shale samples were subjected to infiltration tests with durations between 9 to 27 days, the injected depths of nanoparticle along cracks was determined to range from 190 to 420 μm, as seen by optical microscope images. Higher resolution SEM images show that the maximum infiltration depths of the nanoparticles range from 2 to 5 μm in different crack-free locations. Nanoindentation tests were then conducted under the continuous stiffness measurement (CSM) mode to probe the mechanical properties of the pre-treated and post-treated shale samples. At two indentation depths, the averaged Young's modulus E for the shale sample before and after nanoparticle infiltration significantly increased from 29.5 to 34.0 GPa (at a depth of 500 nm) and from 29.0 to 33.3 GPa (at a depth 3000 nm), respectively. The nanoparticle infiltration and nanoindentation test results demonstrate that nanoparticles can filter into and further strengthen the shale formation.

We also formulated nanoparticles in our drilling fluid and performed the pressure transmission test (PTT) to see their sealing effect on the field cores. A highly favorable plugging result was obtained from the PTT using base mud with nanoparticles. Therefore, it is concluded that our systematic experimental work has delivered results, which support the practice of using nanoparticles to improve wellbore stability for shale formations.
Subsurface Velocity Profiling by Application of Physics Informed Neural Networks
Authors: Kumar Ashutosh , Murali Amal , Priyadarshan Amit
Published: November 2020

Subsurface imaging techniques with improved resolution is the industry's pressing challenge. In this paper, we present a novel Machine Learning based data processing method to generate accurate seismic profiles. Through this method, the processing of humongous acoustic data and subsequent inference of subsurface properties is significantly expedited. The work being presented is an application of a recently developed novel class of algorithms called the Physics Informed Neural Networks (PINNs).

The method has been proven in its efficacy for approximating the solutions to Partial Differential Equations (PDE) governing complex physical phenomena and in data-driven discovery of the underlying PDEs such as the Navier-Stokes system.

Herein, we have followed a two-stage procedure. Stage one is the accurate prediction of spatiotemporal propagation of a seismic pulse through a simulated domain resembling thesubsurface. For this we developed a simulator to generate vast amounts of virtual seismic data. Dense Deep Neural Networks (DNN) were used to overfit the data so that it approximates the solution to the wave equations. This was followed by the data-driven discovery of local velocities in different reflector layers. In the second stage, we have extended the algorithm to infer the real subsurface velocity profile based on the data collected at receiver positions during an actual seismic survey from Volve, a field on the Norwegian continental shelf.

Moreover, we have bench-marked and established the performance of various models in their ability to learn the receiver data obtained from a simulated 2D seismic survey. The results are promising as the network chosen can learn the receiver data with a minimal number of iterations and with near-perfect accuracy. The models were further tested in their ability to represent solutions of the wave equation in the spatiotemporal domain and in their ability to represent the actual subsurface velocity profiles.

The novelty of this paper lies in the overlap of a nascent-stage deep learning tool, called PINNs, with seismic data processing to expedite and improvise high-resolution subsurface imaging. For this, various other uncommon developments were done such as that of adapting PINN as a dynamic wave function approximator. Moreover, the effectiveness of the proposed method is numerically demonstrated by the excellent accuracy obtained when validated against the velocity profile from the field as well as the velocity profile from the simulator.
Progressive Collaborative Planning Approach
Authors: Elkhozahi Hany , Hamdan Hanan , Alhadhrami Abdulla
Published: November 2020

Upper Zakum field is a mega offshore field, in which ADNOC Offshore is investing a lot of resources to bring development target to reality. In order to achieve the company's strategic milestones, over 300 minor and major projects are being implemented utilizing a tremendous number of major and minor resources. This excessive volume of data is communicated daily from each division independently with different templates/format, which isn't reflecting the complete image of operations and development progress status. Therefore, to achieve those strategic milestones, an effective planning process across multiple functions within different organizations and at various locations, along with an efficient tracking system was established. Operation Planning & Support teams developed Upper Zakum 5 years business plan alongside the Integrated Master Activity Plan (IMAP) to identify the required scope ensuring safe guidance of the company towards achieving its targets while sustaining the integrity. IMAP leverages the communication level among all stakeholders, particularly during the planning phase, to enhance the effectiveness and realism of plans, in addition to, providing flexibility in reviewing the plan from different perspectives through the ability to produce various layouts aligned with specific requirements. IMAP website has been established to enhance communication and ensure that all stakeholders have adequate information that supports maintaining consistency in the workplace and preventing any ambiguity. The website provides an efficient and prompt access to review planned activities for a particular project as well as forecasted activities on a particular asset location. IMAP website has ensured the effective distribution of up to date information on each asset location such as objectives, responsible team, resources allocation, material delivery time, execution timeline, and planned shutdown windows. This collaborative approach leads to early discovering of major resources clashes and abolishes them during the planning phase, ensuring the best utilization of resources and completing the required scope within the time boundary; as well as, enhancing the predictions of production, water injection and improve the accuracy of budget outlook; in addition to data-driven realistic decision-making.
Enhancing Foam Stability Through a Combination of Surfactant and Nanoparticles
Authors: Almubarak Majed , AlYousef Zuhair , Almajid Muhammad , Almubarak Tariq , Ng Jun Hong
Published: November 2020

Gas injection is amongst the oldest and most used enhanced oil recovery (EOR) methods in the petroleum industry. Nevertheless, gas EOR is subject to poor macroscopic sweep efficiency due to the higher mobility and lower density of gas compared to reservoir fluids. Foamed-gas injection can regulate the mobility of gas by trapping a large fraction of the gas inside the porous medium, thereby increasing its apparent viscosity and reducing its relative permeability. However, the poor stability of foam at harsh reservoir temperature and salinity conditions is a major limitation that hinders the effectiveness of the foam flood. A combination of surfactant and nanoparticles (NPs) provides a novel solution to foam stability challenges.

This study evaluates the role of NPs on enhancing foam stability. Static and dynamic laboratory tests were conducted along with particle size and zeta potential measurements to capture the foam stability and strength in porous media for a cationic surfactant combined with surface modified silica NPs. The static bulk foam stability was determined by measuring the foam half-life over time. The dynamic foam stability was determined through the mobility reduction factor (MRF) using a micromodel apparatus. The tests were carried out on a variety of NPs concentrations and fixed surfactant concentration.

The results from the experiments show that the use of surfactant combined with NPs enhances the stability and strength of the generated foam when compared to the use of surfactant alone. The foam static tests show that the mixture of NPs and surfactants produces foams with smaller bubbles and longer half-life when compared to those in the absence of NPs. The results also demonstrate that the concentration of surfactant and NPs is a crucial parameter for foam stability and that there is an optimal concentration of NPs for strong foam generation. In porous media, the addition of NPs to surfactant solutions results in larger pressure differences across the micromodel chip and, accordingly, greater reduction of gas mobility when compared to those using surfactant solution alone. The results also reveal that the generation of NPs flocs is the main mechanism of foam stabilization enhancement.

This work shows that using NPs at carefully selected concentrations in combination with surfactant can improve the foam static and dynamic stability in porous media, effectively lowering the mobility of the injected fluids and, eventually, improving the sweep efficiency of gas compared to the typical application of using surfactant alone.
Understanding Mauddud Waterflood Performance in a Heterogeneous Carbonate Reservoir with Surveillance Data and Ensemble of Analytical Tools
Authors: Konwar Lakshi , AlOwainati Ebrahim , Nemmawi Nadia , Michael Dowen , Ali Almuntaser
Published: November 2020

Bahrain oil Field being the first oil discovery in the gulf region in 1932 is now in a mature stage of development. Crestal gas injection in the oil bearing, under saturated, layered and heavily faulted carbonate Mauddud reservoir has continued to be the dominant drive mechanism since 1938. Thirty-eight 40-acre 5-spot waterflood patterns were implemented from 2011 to 2012. These patterns were located in both South East and North West part of Mauddud reservoir with a maximum injection rate of 80 MBWPD. With less than 10% PV water injected as of December 2012, premature water breakthrough was observed in most of the producers. Rapid water breakthrough in Mauddud A (Ba) is attributed to presence of high permeability vugs and layers resulting water cycling and poor sweep in the matrix leaving bypassed oil. Following recommendations from the 2013 partner Peer Assist, the South East and North West waterfloods have been converted from pattern to peripheral with down dip wells providing water injection. Peripheral re-alignment has arrested the production decline, reduced water cut and stabilized the production.

Surveillance data such production logs, reservoir saturation logs, noise logs, temperature and tracer data form the basis of understanding waterflood performance. Additionally, an array of analytical tools were used for diagnosis and analysis. Amongst the diagnostic tools, the Y- function helped to understand water cycling and sweep; the modified-Hall plot helped understand high-permeability channel or lack thereof and water-oil-ratio (WOR) gave the clue on fluid displacement. Additional plots such as "X" plot, hydrocarbon pore volume injected vs. recovery, Jordan plot, Cobb sweep plot, Stagg's plot and decline curve analysis were generated to gain insight on the sweep, recovery and remaining moveable oil of the waterflood.

Based on the waterflood analysis, a field study was initiated in December 2016 by shutting more than 80% of water injection followed by complete shut-in in September 2017. The motivation was to reduce the water cut, improve production taking advantage of gravity drainage effect of gas injectors located up dip of waterflood areas. The implementation of water injection shut-in is still ongoing in the field and pressure/production performance is being closely monitored.

This study underscores the importance of fit-for-purpose surveillance data along with ensemble of modern analytical tools to diagnose and analyze waterflood performance. This understanding also paves the way for much improved learning to take appropriate actions and help devise long-term reservoir management strategy.
Using Integrated Process and Electrical Digital Twins to Right-Size Electrical Systems and Reduce Capital Expenditures
Authors: Parker Janet
Published: November 2020

Electrical system design in capital projects takes place very early in the cycle because large motors and gas powered generators are long lead time items and plant assets require power during installation. This means that electrical design employs only preliminary process design data and instead relies on simple load factor formulas. Under-designing the electrical system could mean the process cannot reach nameplate capacity, which could have significant financial consequences. If a similar process unit has already been built, an accurate simulation of that process could be used to right-size the electrical system, especially if the process simulation is connected to an equally accurate electrical simulation. This would allow engineers to evaluate process and electrical dynamics to ensure electrical power always meets process demand and that the electrical design is adequate for a variety of real life scenarios, such as plant startup and shutdown, process upsets, and unplanned grid outages.

This paper explores the potential cost savings during a capital project and into the operational phase, the significant challenges in creating an accurate process simulation, and other use cases for a mixed process and electrical simulator can provide. A simple study was performed for a client where both the electrical design data and the process simulator was available to determine if the simulator was accurate enough to calculate load demand and if the motors were oversized in the unit. The crude unit was selected because it contained the largest number of medium voltage motors and was relatively easy to operate. The model and the historian predicted that the motors were oversized between 15–63%. Extrapolating the excess power to cost could reach 1.3 MUSD per year.
Unlocking Stratigraphic Trapping Potential in SE Abu Dhabi
Authors: Al Ghafri Thuraya , Liu Jinhui , Al Aufi Yousuf , Aghbari Ibrahim , Al Katheeri Faaeza , Jung Hyunyoung , El Noamany Said
Published: November 2020

The study area is located in the south east of Abu Dhabi, covering approximately 4,000 km2. During several prospectivity studies carried out since 2012, high exploration potential was identified for Lower Cretaceous stratigraphic traps. To resolve the Aptian subtle trap configuration and lateral seals, it was decided in 2017 to acquire a 2,146 km2, high resolution 3D seismic cube. The paper will describe the planning, acquisition, processing and current interpretation results of this seismic campaign.

Prior to the 3D seismic acquisition, a parameter design study was conducted to assess the requirements for the seismic acquisition and to insure that potential stratigraphic traps can be imaged in the newly planned 3D seismic cube. The processing was conducted on a zipper by zipper basis, allowing the processing of the acquired data while the remaining acquisition was still ongoing. It was conducted in a south to north direction, allowing the interpretation of the southern most zipper first which has greatest potential according to the existing prospectivety studies.

Initial interpretation results confirm the challenge to interpret actual clinoform shapes at the Aptian level. Furthermore, multiples initially obstructed the seismic interpretation. Additional processing was carried out to reduce the impact of multiple energy on the seismic events. It was observed that noise reduction was acheived after the integration of each zipper, as the velocity model was further improved with each step. Albeit with these challenges, attribute extraction has been proven to be highly valuable in defining clinoform trends due to the high quality of the acquired seismic. Based on the seismic interpretation results, an exploration campaign to unlock the potential of the Aptian and deeper prospectivity in the East of the study area has been planned.

For the first time in ADNOC and the emirate of Abu Dhabi, a 3D seismic survey was designed, acquired, processed and interpreted to target stratigraphic traps as the main objective. To accelerate the exploration campaign, the 3D seismic data was processed while the acquisition was ongoing. With this strategy, an 18-month turnaround from start of acquisition in December 2017 to the spud of first exploration well in May 2019 was achieved.
Low Polymer Retention Opens for Field Implementation of Polymer Flooding in High Salinity Carbonate Reservoirs
Authors: Skauge Arne , Skauge Tormod , Pourmohamadi Shahram , Solbakken Jonas , Kedir Abduljelil Sultan , Djurhuus Ketil , AlSumaiti Ali , Masalmeh Shehadeh
Published: November 2020

Polymer flooding has been a successful EOR method in sandstone reservoirs for decades. Extending polymer flooding to carbonate reservoirs has been challenging due to adsorption loss and polymer availability for high temperature, high salinity (HTHS) reservoirs. In this study, polymer flooding for carbonate reservoirs is moved forward as we show that HTHS polymers can exhibit low adsorption and retention in carbonate reservoir rock at ultra-high salinity conditions.

Carbonate reservoir core plugs with permeabilities ranging from 10 mD to Darcy range were used for the adsorption/dynamic retention studies. The dynamic retention experiments made use of water-soluble tracers as comparison for the polymer transport in porous medium. The synthetic formation water had ultra-high salinity, i.e. 180 000 mg/L TDS with a hardness of 19 %. In addition to experiments performed on single phase water saturated cores, experiments were also performed on crude oil aged reservoir core samples. The aged core samples were flooded to Sorw by water flood or by centrifugation.

The implementation of polymer flooding in carbonate reservoirs has long been restricted due to adsorption and retention. Most polymers for Enhanced Oil Recovery (EOR) are negatively charged. It has long been assumed that the rock surface is primarily positively charged in carbonate rock. The argument of electrostatic attractive forces indicates high loss of polymer due to adsorption. However, the rock surface charge in carbonates may vary with presence of surface biofilms, oil layers and highly varying pore geometries. Measurements of surface charge have shown that this assumption has been too simplistic and that some surfaces are negatively charged or near-neutral due to earlier mentioned effects or ion composition, hardness and total ionic strength. Furthermore, wettability is a key factor. The results of the retention experiments on aged carbonate reservoir rock, show that retention is reduced by a factor of 4-6 when remaining oil is present. This is highly surprising when the ultra-high salinity (180 000 ppm TDS) is considered. The paper shows detailed analysis of retention experiments and discusses the influence of oil, salinity, and polymer chemistry on retention in carbonate rock.

Retention is a key factor for implementation of polymer flooding in carbonate reservoirs. This study shows that new, commercially available HTHS polymers can be applied for polymer flooding in carbonate reservoirs without a high loss of chemicals. The results obtained show a positive impact on economic feasibility of polymer EOR in carbonates. The solutions found here can be applied to similar reservoir conditions and facilitate polymer flooding in HTHS carbonate reservoirs. Pilot tests based on these results are ongoing at the time of writing.
Peculiar Structural Geometry of Abu Dhabi Fields
Authors: Noufal Abdelwahab , Shehab Abdulla , Obaid Khalid
Published: November 2020

A reasonable model for folding evolution in Abu Dhabi is presented answering the questions of the many interpretations for the folding patterns. If these folds related to the compressional forces, then why they did not represent series of anticlines and synclines? Why they dissected? Why showing different amplitudes from the deflection to the hinges zones? And finally, why the main geometry is open folding style and did not showing step dipping limbs towards the direction of the compression more than the other limb?

The giant Fields of Abu Dhabi, UAE possess different geometries and structural patterns. These patterns can be subdivided into two main categories, salt related, and tectonic related. The tectonic related patterns are mainly folding related faults. Most of the fields are double plunging anticlines for the fault related tectonic and four-way domal anticlines in salt related, with few out of both possess unusual structural geometry. This paper addresses these structural patterns in order to shed lights on the trapping mechanism, in a multi-disciplinary approach of well data, seismic, potential data and outcrop analogues. The initial fold axes were determined; the axial plane and direction of heterogeneous shear displacement responding to the first folding and refolding phases were addressed. Unique shaped folds can be grouped in 6 major patterns that can be differentiated into:

The first pattern evolved as dip-closed triple plunging anticline with a northeastern plunge and the southern plunge is bifurcated into two trends; SE and SW. Refold structures showing physical orientation of the first and the second fold generation in a closed pattern. Cone shaped pattern, which possess extended northern hinge zone, while the southern closure is tapering in nature. Snail and Tongue shaped patterns, which are deep rooted by salt diapir. Zigzag shaped pattern, which is mainly evolved in response of connecting pop-up structures related to wrench faults. Chevron High amplitude closed anticline, which is the only and unique pattern, as all others are open folds.

A close relationship of the kinematics and timing between high-angle strike-slip faulting and upright folding is established for the Cretaceous systems. Folding accompanied tectonic denudation developing elongated plunging anticlines with fold axes both parallel and perpendicular to the direction of transpression. The strike-slip systems trending NW-SE of transpressional forces led to evolution of most of the anticlinal fields of tectonic nature in Abu Dhabi.

The structural patterns of the fields and their kinematic evolution leads to understand their genetic and dynamic evolution and hence understanding the trapping mechanisms effectively.
Challenges in Execution of Brownfield Offshore Oil & Gas Projects
Authors: Kumar Naresh , Mukherjee Debarati , Paul Raju , R. Kamal Faris , Takieddine Oussama
Published: November 2020

The execution of large scale Brownfield Offshore Oil and Gas projects remains a challenge mainly due to space constraints on existing platforms and minimum production shutdown requirements from Client. The objective of this paper is to explain the design innovations to overcome the challenges in brownfield project execution and the implementation of electrical changeover philosophy with minimum production shutdown.

The innovative technical solutions are discussed to solve the space constraints on the existing platforms. This paper also discusses the methods to cut down the process shutdown period. Various value engineering ideas are presented to solve the actual technical issues faced on site while executing the brownfield project.

There are many challenges in executing a brownfield project. While each project offers unique set of technical challenges, some common challenges are discussed in this section. The mitigation measures to solve the technical issues are also covered below for some items. However, the value engineering ideas, technical innovations and mitigation measures for the major points are presented in next section. This section is mainly for highlighting the challenges faced during project execution.
Autonomous Inspection System for Anomaly Detection in Natural Gas Pipelines
Authors: Qassab Abdullah , Bhadran Vishnu , Sudevan Vidya , Sharma Arjun , Karki Hamad , Shukla Amit , Al Habshi Mohammed Hashem
Published: November 2020

Oil and gas industry operates according to stringent standards that primarily strive to keep the pipeline transportation and other related operations efficiently while maintaining and practicing high standards of industrial safety. Due to which, the routine inspection and maintenance of underground/overground structures became a challenging process. Over the years, performance based integrity management programmes became popular and it have been implemented for managing the safety and environmental risks associated with hazardous oil or gas pipelines. Pipeline safety and integrity team must verify, repair and certify the integrity of pipelines that could leak or failure in the future. Internal inspection using pipeline inspection gauges (PIG) are considered expensive and the need for surface preparation procedures makes the inspection operations time consuming. Whereas, external survey operations are carried out by highly trained and certified inspection/survey team where they manually identify pipeline leakages or any visible damages. External manual inspection is conducted using various handheld devices and recorded data is later analyzed to identify and locate the possible anomalies. Relatively high surrounding temperatures and uneven terrain makes the manual survey a mundane mission. The shortcomings and the challenges of the conventional external inspection and survey mechanisms are tackled by introducing a mobile robotic platform equipped with non-invasive magnetometric diagnosis (NIMD) system which allows non-contact anomaly detection from a distance of up to 2-3m from the underground pipeline metal core without unearthing or any surface treatments such as coating removal that are performed in the conventional techniques. The proposed autonomous pipeline inspection system has various sensors that can precisely locate, navigate and detect the underground pipeline faults. A novel hierarchical controller which was developed in our previous studies was utilized and employed for the navigation of vehicle over the buried infrastructures. The effectiveness and the performance of autonomous system was tested on real field conditions and the true ability of the system was showcased to detect the underground pipeline anomalies even in extreme environmental conditions.
Utility of Image Logs in Understanding Flow Profile Patterns: Case Study from Onshore Field, UAE
Authors: Girinathan Sajith , Al Zeyoudi Fatmah , Pillai Anit , Kutty Abdurahiman , Ayoub Walid
Published: November 2020

This paper displays an example of the power of data integration. Multiple sub-surface datasets viz., Bore Hole Images (BHI), triple-combo logs, core data, production logs and geomodels were tied together to throw light on suspicious injection profile patterns observed in a horizontal well drilled in the Thamama Group. This well was drilled in an onshore green field.

The production log provided information on injection profile patterns and quantity of fluid intake per zone along the drilled well path. Bore Hole Images (BHI) were processed and analysed for structural features including fractures and faults. Advanced analysis was performed on BHI to gather information on diagenesis along well path. Emphasis was put on extraction of moldic (vuggy) porosity content. Allied LWD resistivity, density, gamma ray and porosity logs were used to calibrate and back-up BHI-based findings. Core descriptions, core photographs, and petrographic analysIs results from offset vertical wells were looked-into in detail to understand diagenesis better, in the adjoining area of candidate well. Structural events identified at well scale were calibrated to field-scale using up-to-date geomodels.

The integrated approach helped in comprehending flow profile patterns in candidate well. Prior to this study, it was assumed that the observed flow profile behavior was related to factors like tool malfunction, well trajectory and even large open fractures. However, post-study findings revealed clear diagenetic control on injection profile (and zonal intake). The role of fractures were observed to be minimal to negligible in this case.