bluuebunny/crossref_metadata_2025_split huggingface dataset:
Wellbore Integrity During Production and Drilling Risk Analysis in Gas Hydrate Bearing Sediments by Coupled THMD Model
Authors: Wang Yarlong , Yuan Yuan , Chai Yutong 
Published: April 2023

Abstract
Wellbore integrity in a gas hydrate bearing formation during drilling and production is a great challenge in the energy industry since a complex thermal-hydraulic-mechanical interaction with decomposed solid hydrate process is involved. A wellbore temperature increase and/or depressurization process may induce additional stresses and thermal and fluid flows, which may trigger wellbore instability, sand production, and undesired fracturing. Production-related wellbore integrity issues such as solid production during wellbore depressurization or heating are also widely observed and studied. To understand the thermal-hydraulic-mechanical behavior with hydrate decomposition (THMD) process and to simulate the THM responses of hydrate gas bearing sediments to wellbore pressure and temperature variations under a given in-situ stress regime during drilling and production, a fully coupled THMD model is presented in this paper. The conceptual THMD model with simplified semi-analytical solutions for the induced stress, pore pressure, and temperature at the wellbore and inside the formation is discussed. A linear Mohr-Coulomb criterion is utilized to define the onset of the wellbore instability or plastic yielding when sand production defined by effective plastic strain (EPS) is considered with a cohesion dependent on hydrate saturation. Numerical method with Laplace transformation is used to solve the transformed homogeneous PDE. We conclude that thermally- and hydration-induced stresses will affect wellbore integrity during hydrate gas production due to wellbore pressure reduction and temperature increase. Unlike the stress perturbation in the conventional gas reservoir, critical temperature and pressure for the equilibrium phase change must be surpassed to induce additional incremental stresses due to the hydrate decomposition. Additional fluid mass and energy transfer may take place with induced temperature and pore pressure because of the hydrate decomposition/recomposition. In addition, the hydrate saturation changes due to the typical drilling strategy applied may reduce the hydrate formation significantly, which will affect the design of production pressure control and management. Thus, pressure optimization is crucial for both maximum production and wellbore integrity.
High Density Geopolymers: A Step Forward Towards Low Carbon Footprint Cementing Operations
Authors: Abdelaal Ahmed Elsayed , Elkatatny Salaheldin Mahmoud 
Published: April 2023

Abstract
The utilization of ordinary Portland cement (OPC) in well cementing is accompanied by technical and environmental problems, leading researchers to explore alternative materials that address these issues and promote eco-friendliness. Geopolymer technology, widely used in construction and other industries, has not yet been fully implemented in oil and gas well cementing. Industrial waste materials, such as Class F fly ash (FFA), can be utilized to improve cement properties or create new cement binders. Hematite is used as a weighting agent to increase cement slurry density. However, heavy particle sedimentation in cement and geopolymer slurries is a significant issue that leads to heterogenous properties along the cemented section. This study introduces a new class of geopolymers that use both hematite and Micromax as weighting materials for high-density well cementing applications. One system only used hematite, while the other used both hematite and Micromax in an effort to eliminate sedimentation issues associated with hematite in geopolymers. The effects of adding Micromax on different FFA geopolymer properties were also evaluated. The study evaluated mixability, rheology, and pumpability to determine the mix design, which was then used to examine other properties such as strength, and density variation. The results showed that adding Micromax to hematite reduced the average density variation from 12.5% to 3.9%. Micromax addition also decreased plastic viscosity by 44.5% and fluid loss by 10.5%. Both systems performed closely in terms of strength.
Model Testing of a Passively Controlled 15 MW Floating Wind Tension Leg Platform
Authors: Udoh Ikpoto Enefiok , De Ridder Erik-Jan , Williams Rebecca , Vinayan Vimal , Gant Frederick , Bouman Gijs , Chen Quan 
Published: April 2023

Abstract
This paper discusses the application of a novel passive control technology (Rotating Tension Element Damper, RTED) in attenuating dynamics of a floating wind tension leg platform (TLP) to significantly reduce fatigue and strength loads which ultimately lower the cost of the system. Comprehensive pre-Front End Engineering Design (pre-FEED), including wave basin testing, was carried out to develop the TLP integrated with the RTED. The integrated application of the RTED to a 15 MW floating wind TLP is the first of its kind, and the assessment features model testing performed at 1:60 scale in the wave basin using operational and extreme seas. Results indicate that the RTED attenuates dynamics in all components of the system, over a broad range of frequencies. Findings also reveal complexities which can be associated with dynamic attributes of control system embodiments at sub-scale, thereby providing insights to avoid such effects in full-scale applications.
SIIBED: An Updated Subsea Iceberg Risk Model for the Grand Banks
Authors: King Tony , Turnbull Ian , Stuckey Paul 
Published: April 2023

Abstract
As part of the SIIBED program, a subsea risk model for the Grand Banks was updated to reflect observed changes in the iceberg regime on the Grand Banks since the 1980s. This risk model is used to calculate interaction rates between free-floating and scouring icebergs and subsea infrastructure. The changes to the iceberg regime are described, along with the updates to the subsea risk model and changes in previously calculated iceberg interaction rates for a proposed facility. A methodology for integrating output from other SIIBED tasks into the risk analysis is outlined. Components of a source-to-sink model for understanding past changes in the iceberg regime, as well as future anticipated changes, are discussed.
Cost Effective Fixed Offshore Wellhead Platforms at Shallow Water Moderate Environment Considering Deck Space for Rig-Less Well Interventions
Authors: Chatterjee Prabir Kumar , Shah Jinesh 
Published: April 2023

Abstract
This paper proposes a nonconventional substructure of a fixed offshore wellhead platform that can support a reasonably large deck required for housing 8 wells and rigless well-intervention equipment. The large deck area is considered to avoid hiring of costly jack-up rig or lift boat. Unlike conventional jackets, some conductor guides/sleeves are modified like jacket legs, however, conductors are kept axially free to move through the sleeves. The mudmats are modified to include in the overall load-bearing capacity of the structure. The lower deck (41m × 25m) will accommodate all production equipment and the upper deck will be reserved mainly for temporary well-intervention equipment. Structural design is performed for the proposed platform at 33m water depth due to wave, wind and current loads. Simulated collapse analyses show adequate reserve strength for the structure against extreme wave loads along different directions. The proposed design can provide significantly larger deck space that may be reserved for temporary well-intervention equipment compared to conventional designs without considerable increase of structural steel.
Old Wells, New Purpose: Key Considerations for Re-Purposing Mature Wells and Fields for Carbon Capture and Storage (CCS)
Authors: Hoskin Edward Michael , Heller Jakob 
Published: April 2023

Traditionally, when the production cycle of an oil or gas or oil & gas field reaches its economic end of life, the top side facilities are dismantled, the wellbore is permanently plugged and abandoned, and the surrounding land or seabed is returned to its natural condition. Such a procedure is commonly referred to as decommissioning and it is a complex, multi-step process that is expensive, with costs even higher for offshore and deep-water fields and wells.
At the same time as increasing numbers of oil and gas assets are reaching their end-of-life and need to be decommissioned, governments world-wide are committing to reach a net zero target for CO2 emissions in the coming decades. With these two concurrent commitments there is now the opportunity to evaluate the potential for re-use of those to-be-decommissioned wells and fields for the use of CO2 injection and storage, commonly referred to as CCS or carbon capture and storage. Re-using wells and fields for CO2 injection provides not only potential cost saving benefits but also promises to reduce the time required for developing the necessary CCS infrastructure because much of it will already be in place. The process of converting hydrocarbon wells to CO2 storage wells has been considered in several planned projects, including the P18-4 depleted gas field near the coast of Rotterdam, part of the wider Porthos project, and Peterhead project in the North Sea (Arts et al., 2012; Marshal et al., 2018). Other inherent advantages to re-use include the availability of rich datasets of downhole measurements including logs, core samples and any subsequent lab analysis, and also in-depth field understanding based on potentially multiple well operations. The operators also have the possibility of turning decommissioned wells into a source of profits, or at least covering decommissioning costs, by selling CO2 storage capacity to others.
However, the process for facilitating re-use of wells for injection of CO2, even into a saline aquifer, is far from a simple process of reverse engineering typical oil and gas production practices because there are a number of factors to consider. These include both geological, including reservoir pressure and seal capacity, and engineering not only from a well construction and integrity process but also reservoir engineering and the feasibility of a reservoir to accept the volume and rates of CO2 required to make economic sense for either a new field CCS site or in a re-use case.
Study of Cold Cracking on Offshore Platform Structural Fillet Welds from 440MPa Yield Strength Steel and its Prevention
Authors: Mohandas Subindas Melapurakkal , Cho Min Hyun 
Published: April 2023

Abstract
This paper presents a study conducted to evaluate the centerline weld cracking observed on primary structural Node's fillet weld joint connections made of 440MPa Yield Strength Steel using Flux Cored Arc Welding (FCAW) process in the offshore structures during the fabrication and assembly. Non-Destructive Examination (NDE) – Magnetic Particle Inspection (MPI) was selected to inspect the fillet weld joint connections because RT or UT is not practical. Considering the possibility of delayed cracking, fillet welds were inspected using MPI after 3 days of weld completion, and MPI examination has not captured any indication. The significance of cracks observed on these initial MPI examined weld joint connections was noticed by visual inspection after 3 weeks of weld completion, thus, the extent of NDE was conducted and observed the long-delayed cracks, which doubts the possibility of long incubation time of cracking. The laboratory examination of the weld center line crack sample had been performed to acquire the key evidences to verify the damage mechanism as a cold cracking. In this paper, the identification of the major causes of Cold cracking, the discussion of the possible causes of long incubation time, and the optimization of the weld joint design had been studied. It also covers the correction methodology that needs to be adopted to prevent the recurrence.
State of the Art Flow Loop Experiments with Real Fluids to Enable Simulator Matching with Field Conditions
Authors: Johansson Peter Sassan , Kjeldby Tor Kindsbekken , Johnson George William , Valle Arne , Hu Bin , Xu Zheng Gang , Wang Xiaofeng 
Published: April 2023

AbstractAn experimental campaign was conducted in Equinor's high pressure flow loop in Porsgrunn with the objective of establishing a high-quality real gas condensate data set for use in modeling steady state flow as well as the specific surge wave phenomena in the Mikkel and Midgard (part of Åsgard) fields on the Norwegian continental shelf. The Mikkel and Midgard fields have been naturally flowing to Åsgard B since 2003 with introduction of the Åsgard Subsea Compression station in 2015 as a major upgrade. The surge wave phenomenon is per today observed in flowlines both upstream and downstream the compressor station, representing challenges with respect to liquid level control both in the scrubber upstream the compressor station as well as topside Åsgard B. Several flowlines are operated with so called ‘’minimum flow limitations’’ representing the minimum production rates at which the flowlines can be operated with acceptable liquid content and flow fluctuations due to surge waves. In order to plan future operations and restructuring initiatives, predictive tools able to capture these phenomena from a quantitative point of view are required. Data based on realistic fluid properties and conditions, have been vital for achieving the required flow simulator improvements in close collaboration with the software vendor modeling team. The first part of the paper gives a detailed description of the experimental matrix, the experimental execution, and the data analysis. Emphasis is also given to describe the state-of-the-art instrumentation used to achieve a unique set of high quality three-phase pipe flow data. The second part of the paper describes a modelling effort utilizing User Defined Functions in the multiphase flow simulator to tune/modify the closure laws to better match the experimental data. The improved model is compared with the Åsgard field data. The model will be used to aid future operations of the field. In an accompanying paper the software vendor has used the new data to improve the general multiphase flow simulator model.
Influence of Hydrogen Sulfide on Adsorption Behavior of CO2/CH4 Mixtures in Calcite Nanopores with the Implications for CO2 Sequestration
Authors: Qian Cheng , Rui Zhenhua , Liu Yueliang , Zhao Yang , Li Huazhou Andy , Ma An , Afanasyev Andrey , Torabi Farshid 
Published: April 2023

Abstract
Injecting CO2 into reservoirs for storage and enhanced oil recovery (EOR) is a practical and cost-effective strategy for achieving carbon neutrality. Commonly, CO2-rich industrial waste gas is employed as the CO2 source, whereas contaminants such as H2S may severely impact carbon storage and EOR via competitive adsorption. Hence, the adsorption behavior of CH4, CO2, and H2S in calcite (CaCO3) micropores and the impact of H2S on CO2 sequestration and methane recovery are specifically investigated using molecular simulation. The Grand Canonical Monte Carlo (GCMC) simulations were applied to study the adsorption characteristics of pure CO2, CH4, and H2S, and their multi-component mixtures are also investigated in calcite nanopores to reveal the impact of H2S on CO2 storage. The effect of pressure (0-20 MPa), temperature (293.15-383.15 K), pore width, buried depth and gas mole fraction on the adsorption behaviors are simulated. Molecular dynamics simulations (MD) were performed to explore the diffusion characteristics of the three gases and their mixes. The amount of adsorbed CH4, CO2, and H2S enhances with rising pressure and declines with rising temperature. The order of adsorption quantity in calcite nanopores is H2S&gt;CO2&gt;CH4, whereas the order of adsorption strength between the three gases and calcite is CO2&gt;H2S&gt;CH4 based on the interaction energy analysis. At 10 MPa and 3215 K, the interaction energies of calcite with CO2, H2S, and CH4 are -2166.40, -2076.93, and -174.57 kcal/mol, respectively. The CH4-calcite and H2S-calcite interaction energies are dominated by van der Waals energy, whereas electrostatic energy predominates in the CO2-calcite system. The adsorption loading of CH4 and CO2 are lowered by approximately 59.47% and 24.82% when the mole fraction of H2S is 20% at 323.15 K, reflecting the weakening of CH4 and CO2 adsorption by H2S due to competitive adsorption. The diffusivities of three pure gases in calcite nanopore are listed in the following order: CO2 &gt; H2S &gt; CH4. The presence of H2S in the ternary mixtures will limit diffusion and outflow of the system and each component gas, with CH4 being the gas most affected by H2S. The CO2/CH4 mixture can be buried in formations as shallow as 1000-1500 m, but the ternary mixture should be stored in deeper formations. The effects of H2S on CO2 sequestration and CH4 recovery in calcite nanopores are clarified, which provides theoretical assistance for CO2 storage and EOR projects in carbonate formation.
A Retrofittable Instrument to Monitor and Record Strain on Subsea Structures
Authors: Smerdon Andy , Cook Graham 
Published: April 2023

Abstract
In mature offshore hydrocarbon fields, an increasing number of aging assets have reached or exceeded design life, meaning fatigue is of growing concern. Digital twins incorporating a fatigue model are typically used to assess structural integrity and inform decisions on life of field extension. However, they rely on idealized wave models which cannot truly reflect the hydrodynamic loading, which leads to uncertainty and conservatism. The operator of the Ninian Southern Platform in the UK North Sea concluded that if strain could be monitored in situ at key subsea locations, they could develop a more accurate relationship between sea conditions and structural loading, which could be used to calibrate the asset fatigue model, providing enhanced understanding of the jacket integrity. We describe the development, validation, installation, and first field results from an instrument designed to meet that challenge.
Retrofitting strain sensors to subsea structural members presents many technical challenges, as neither conventional strain gauges nor cabled connections are feasible in the harsh subsea environment. For the first deployment, the instrumentation required robust attachment to a 1.2 m diameter tubular member situated at 43 m depth, which would withstand 100-year metocean maxima. It needed a strain transfer mechanism for autonomous measurement of the smallest fatigue-inducing strain reversals on three quadrants of the tubular over a two-year period. Strains were to be continuously sampled and recorded at a sufficient rate to accurately capture the peak values. Additionally, accelerations in three axes and wave height derived from hydrostatic pressure were to be monitored. The whole package had to be installed by ROV, and needed to deliver periodic data downloads throughout the life of the instrument.
At the heart of the instrument is a set of environmentally packaged strain transfer mechanisms. These engage with the surface of the structure through spring-loaded actuators that are deployed by the ROV during installation. They allow strains to be measured directly by the instrument’s data acquisition system. These mechanisms were validated and calibrated using specially designed test equipment. Prior to deployment, the complete instrument, including its magnetic attachment system, was tested on a sample pipe section. All instrument subsystems were proven, including a high-speed optical data link for through-water transfer of recorded data, and an acoustic communication system for status updates.
The instrument was successfully deployed subsea in April 2021, and one complete and continuous data set has already been retrieved. The data shows that the instrumentation is able to accurately capture a range of microstrains from the smaller strain reversals during calmer conditions to the larger wave driven strains in storm conditions. This has demonstrated the ability of the system to measure with great precision, while also withstanding very harsh environmental conditions.
Design Tool to Tailor Properties of Cement for P&A Applications
Authors: Jandhyala Siva Rama Krishna , Cuello Jimenez Walmy 
Published: April 2023

Abstract
As oil and gas wells approach the end of their productive lifetime, they must be permanently abandoned. In recent years, there has been a lot of emphasis on creating modeling tools for design tailoring and placement of abandonment plugs. Moreover, it is of equal significance to devise a process and design tool for achieving long-term integrity of abandonment plugs. Such a design tool will help understand and mitigate the risks of thermo-mechanical damage or flow through plugs. A sound underlying design process should demonstrate the following attributes - (i) be flexible to accommodate different load types: structural, thermal, pore fluid, and strain loads that can be rapid or gradual in nature, (ii) communicate stresses, deformation and temperature information between load stages, (iii) allow load application on the top, bottom, and radial directions of the plug, (iv) evaluate risk of mechanical failure and permeable flow, and (v) allow tailoring of cement properties to minimize the risks. As a result, this work presents a design tool that complies with all the attributes described.
The design tool has been used to model a cement plug interacting with its near wellbore environment. It has the necessary geomechanical and transient features to model rapid or gradual changes in pore pressure and stress to subsequently assess the risk of fluid flow, mechanical failure in shear, tension and/or debonding. The design tool is verified by simulating the construction phases and operational loads of a representative plug job and then comparing its outcome to the expected and/or actual behavior. The effect of plug in-situ stresses and stress anisotropy of the rock are demonstrated. Further, the response of formation's permeability changes from 50 nano Darcy to 5000 μDarcy is used to highlight the impact of fluid communication between the adjacent formation and the abandonment plug.
Interestingly, the verification results align with the expected behavior. Pore pressure buildup is found to increase or decrease the risk of plug failure in shear mode depending on whether the plug is cured in compression or tension, respectively. An increase in formation permeability shows a flow diversion from the plug into the rock, thus, limiting the stress build-up in the plug. For the case analyzed herein, the encountered impact of rock stress anisotropy is minimal.
Ultimately, the design tool demonstrates how a typical abandonment construction and operation process can be simulated to assess the risk of failure and fluid flow through an abandonment plug. It also highlights the critical factors that govern a plug's response, which in some cases includes the role of formation and casing.