Deep-water Environments Research Articles

Observing the deepwater environment using an underwater vehicle

Observing the deepwater environment using an underwater vehicle

Effects of Typical Supplementary Cementitious Materials (SCMs) on the Bonding Property of Cement with Casing under Shallow Formation of Deep-Water Environment

Due to low temperature environments and other factors, the performance of cement slurry is affected by deep-water shallow formation cementing, which makes it difficult to ensure the interface bonding quality. The objective of this study is to investigate the effect of fly ash (FA), metakaolin (MK), and microsilica (MS) as supplementary cementitious materials (SCMs) by replacing 5–20% of the cement on the bonding property of cement with casing in the shallow formations of deep-water environments. This is based on the cementing conditions for the 20″ surface casing in the deep-water shallow formation of the LS18-1 well area. Under the 30 °C experimental conditions, the results showed that the compressive and bonding strength of cement with FA and MS decreased gradually as their dosage increased. In contrast, compared with the control group (BG0), the compressive strength of the MK group increased by 25.6%, 32.1%, and 24.2% under the optimal dosages (MK15, MK15, MK20) at 3, 7, and 14 days (d), and the bonding strength increased by 73.6% at 3 d (MK15) and 34.9% at 7 d (MK15). The test analysis showed that MK can promote cement hydration and generate more hydration products, which are conducive to cement-casing interface cementation. Additionally, it can improve the pore structure, reduce the fractal dimension of the pore volume, and ensure a more reasonable distribution of cement stone crack openings.

Study on shock wave load characteristics from condensed phase explosive detonations in deep-water explosions

This study investigates shock wave load characteristics from condensed phase explosive detonations in deep-water environments using a high-order compressible multiphase solver. Spatial terms of the solver are discretized by fifth-order weighted essentially non-oscillatory reconstruction in characteristic space, while a third-order total variation diminishing Runge–Kutta method is adopted to deal with the temporal terms. The level-set method captures multiphase interfaces, while a programed burn model describes detonation wave generation. Numerical and experimental validations focus on shock waves in explosives interacting with water. Validations across shallow and deep-water conditions align numerical results with theoretical and experimental values. The solver examines shock wave characteristics across varied charge masses and water depths, revealing peak pressure deviations under identical conditions. The numerical simulation results indicate that the similarity of shock wave loads in underwater explosions is evident not only in peak pressures but also in the pressure–time history curves. Through extensive comparative analysis of results, it has been found that existing formulas for calculating shock wave positive pressure durations are not applicable to deep-water explosions. The research findings and analytical methods presented in this paper can serve as crucial references for further studies on the characteristics of shock wave loads in deep-water explosions.

Temporal-Feature-Based Classification of Active Sonar Targets in a Deep-Water Environment

Temporal-Feature-Based Classification of Active Sonar Targets in a Deep-Water Environment

Numerical Modeling of Scholte Wave in Acoustic-Elastic Coupled TTI Anisotropic Media

Numerical modeling of acoustic-elastic media is helpful for seismic exploration in the deepwater environment. We propose an algorithm based on the staggered grid finite difference to simulate wave propagation in the interface between fluid and transversely isotropic media, where the interface does not need to consider the boundary condition. We also derive the stability conditions of the proposed method. Scholte waves, which are generated at the seafloor, exhibit distinctly different propagation behaviors than body waves in ocean-bottom seismograms. Numerical examples are used to characterize the wavefield of Scholte waves and discuss the relationship between travel time and the Thomsen parameters. Thomsen parameters are assigned clear physical meanings, and the magnitude of their values directly indicates the strength of the anisotropy in the media. Numerical results show that the velocity of the Scholte wave is positively correlated with ε and negatively correlated with δ. And the curve of the arrival time of the Scholte wave as a whole is sinusoidal and has no symmetry in inclination. The velocity of the Scholte wave in azimuth is positively related to the polar angle. The energy of the Scholte wave is negatively correlated with the distance from the source to the fluid-solid interface. The above results provide a basis for studying oceanic Scholte waves and are beneficial for utilizing the information provided by Scholte waves.

Seismic sedimentology analysis of meter-scale thin sand bodies in the Jurassic Qigu Formation, Yongjin area, Junggar Basin

Seismic sedimentology is an interdisciplinary field that integrates sedimentary geology and geophysics to accurately characterize the spatial and temporal distributions of sedimentary systems. This paper focuses on the Qigu Formation in the Yongjin area of the Junggar Basin, China. The objectives are to establish a high-resolution sequence stratigraphic framework and to clarify the types of sedimentary systems present. Various technical methods, including 90° phase adjustment, attribute clustering, red-green-blue attribute fusion, stratal slicing, and seismic phase-controlled waveform indication inversion, are employed to restore the vertical evolution history of the sedimentary system and quantitatively characterize the spatial-temporal distribution of the thin sand bodies in the Qigu Formation. The results revealed that the Qigu Formation is divided into a third-order sequence, consisting of a lowstand systems tract and a lacustrine transgressive systems tract. During the lowstand systems tract, a thick channel sand body developed in the delta front, exhibiting a non-muddy, intermittent normal grading structure. The lacustrine transgressive systems tract features thin, discontinuous channel sand bodies with mud layers, also forming an intermittent normal grading structure. Two distinct types of delta fronts are identified: the first, formed during the lowstand systems tract, is characterized by branching subaqueous distributary channels in a shallow-water environment. The second, associated with the lacustrine transgressive systems tract, displays a network-like distribution of subaqueous distributary channels in a relatively deeper-water environment.

Ichnological record in gateways and other high-energy deepwater environments: A palaeo- and neoichnological approach

The evolution of gateways determines variations in palaeo-environmental (ecological and depositional) conditions affecting trace maker communities, hence biogenic structures. With respect to palaeo-gateways, bottom currents and associated deposits (i.e., contourites) may be approached through trace fossil studies. Ichnological analysis -individual ichnotaxa and changes in ichnofacies- of Late Miocene contourites and associated facies from the Rifian Corridor palaeo-gateway (Morocco) reveals a major impact of food supply, flow velocity, seafloor heterogeneity, and hydrodynamic energy. The fact that Eocene to middle Miocene deep-marine deposits -mainly contourites- from the nearby Indian palaeo-gateway (Cyprus) show ichnofacies replacement is evidence of increased bottom-current flow velocity associated with sea level variations. Moreover, ichnofabric changes reflect pelagic, gravitational, and bottom-current processes that simultaneously influence sedimentation. Changes in the trace fossil composition of both areas , and in the shape of burrows, reflect intermittent bottom current processes that governed contourite deposition. Neoichnological studies complement and validate the trace fossil record of high-energy deep-sea environments that can occur in palaeo-gateways. Modern traces ( lebensspuren ) observed on the seafloor show variable features (e.g., diversity, density, morphology) depending on the type of disturbance that high-energy conditions exert on the trace-making benthic fauna. Parameters such as substrate consistency, nutrient availability/distribution, and the duration and intensity of energetic events play a major role in determining lebensspuren features. We conclude that an integrative palaeo- and neoichnological approach is a powerful tool when used to improve our knowledge of benthic ecosystems in high-energy deep-sea environments such as gateways.

Petroleum exploration and production in Brazil: From onshore to ultra-deepwaters

The Santos Basin in Brazil has witnessed significant oil and gas discoveries in deepwater pre-salt since the 21st century. Currently, the waters in eastern Brazil stand out as a hot area of deepwater exploration and production worldwide. Based on a review of the petroleum exploration and production history in Brazil, the challenges, researches and practices, strategic transformation, significant breakthroughs, and key theories and technologies for exploration from onshore to offshore and from shallow waters to deep–ultra-deep waters and then to pre-salt strata are systematically elaborated. Within 15 years since its establishment in 1953, Petrobras explored onshore Paleozoic cratonic and marginal rift basins, and obtained some small to medium petroleum discoveries in fault-block traps. In the 1970s, Petrobras developed seismic exploration technologies and several hydrocarbon accumulation models, for example, turbidite sandstones, allowing important discoveries in shallow waters, e.g. the Namorado Field and Enchova fields. Guided by these models/technologies, significant discoveries, e.g. the Marlim and Roncador fields, were made in deepwater post-salt in the Campos Basin. In the early 21st century, the advancements in theories and technologies for pre-salt petroleum system, carbonate reservoirs, hydrocarbon accumulation and nuclear magnetic resonance (NMR) logging stimulated a succession of valuable discoveries in the Lower Cretaceous lacustrine carbonates in the Santos Basin, including the world-class ultra-deepwater super giant fields such as Tupi (Lula), Mero and Buzios. Petroleum development in complex deep water environments is extremely challenging. By establishing the Technological Capacitation Program in Deep Waters (PROCAP), Petrobras developed and implemented key technologies including managed pressure drilling (MPD) with narrow pressure window, pressurized mud cap drilling (PMCD), multi-stage intelligent completion, development with Floating Production Storage and Offloading units (FPSO), and flow assurance, which remarkably improved the drilling, completion, field development and transportation efficiency and safety. Additionally, under the limited FPSO capacity, Petrobras promoted the world-largest CCUS-EOR project, which contributed effectively to the reduction of greenhouse gas emissions and the enhancement of oil recovery. Development and application of these technologies provide valuable reference for deep and ultra-deepwater petroleum exploration and production worldwide. The petroleum exploration in Brazil will consistently focus on ultra-deep water pre-salt carbonates and post-salt turbidites, and seek new opportunities in Paleozoic gas. Technical innovation and strategic cooperation will be held to promote the sustainable development of Brazil's oil and gas industry.

Combination effects of laser heating and water cooling on the repair performance of Hastelloy C-276 by underwater laser direct metal deposition

The Ni-based Hastelloy C-276 was repaired by in-air and underwater laser direct metal deposition (in-air DMD and UDMD) with four gradient cooling rates (in-air DMD, in-air DMD with interlayer cooling, UDMD and UDMD with each layer re-covered by water). The microstructure and mechanical properties of repaired samples were systematically characterized with respect to the cooling rates. All samples presented good metallurgical bonding and columnar dendrites with epitaxial growth. The underwater environment had a more pronounced acceleration effect on the cooling rate compared to interlayer cooling. The rapid cooling induced intense thermal cycling, resulting in increased dislocation density and grain refinement with primary dendrite arm spacing (PDAS) diminishing from 5.30 to 3.21 μm. Accelerated cooling rate contributed to precipitation of massive M6C carbides. Carbides coarsened (sizes from 257 to 354 nm) and exhibited a reduced content as cooling rate slowed down due to intrinsic heat treatment (IHT). The residual water film in UDMD repair promoted oxide formation. Samples with increased cooling rates exhibited superior mechanical performance. The improved microhardness, tensile and impact properties were primarily attributed to the enhanced fine grain strengthening and Orowan strengthening facilitated via reduced grain size, increased dislocation density and carbide content. Quantities of large-size carbides were detrimental to tensile and impact properties as displayed in the in-air DMD sample with interlayer cooling (carbide size of 341 μm). The study could serve as a reference for in-situ restoration in deep-water environments.

Cadmium isotope evidence for near-modern bio-productivity in the early Cambrian ocean

The Ediacaran–Cambrian transition was one of the major transitions in Earth's history, with mass extinctions and radiation of animals. This event has been linked with perturbations in ocean geochemistry, including redox conditions and the oxygenation of Earth's surface environments. Here we present a highly resolved cadmium isotope record (δ114Cd) from shales deposited in a deep-water environment covering the Late Ediacaran to Cambrian Stage 4. Our δ114Cd data vary from −0.70 to +0.35 ‰ and demonstrate the importance of local redox-dependent burial phases on bulk sediment Cd isotope compositions, which are superimposed on global-scale changes in the Cd cycle. The heaviest Cd isotope composition recorded in the early Cambrian Liuchapo Formation is similar to the modern deep ocean, implying a broad similarity in global Cd cycling, perhaps involving similar organic-Cd burial rates. The provision of bio-limiting nutrients by continental weathering with rising oxygen concentrations in Earth's surface environments could have expanded the habitable area of the ocean and contributed to animal diversification.

Geochemistry of BIF in the Quadrilátero ferrífero, Brazil, as a proxy to neoarchean paleoenvironmental and depositional conditions

Precambrian Algoma-type banded iron formations (BIFs) are biochemical metasedimentary rocks formed in the deep water environment relatively close to centers of volcanic expansion and can be characterized on the basis of their paleodepositional environment and the associated rock types. These rocks may contain geochemical signatures indicative of changes in the redox conditions of the Archean ocean. Such variations in the Meso- and Neoarchean are crucial in understanding the processes that led to the gradual increase of oxygen in the early atmosphere, culminating in the Great Oxidation Event (2.4–2.3 Ga). Oxide- and carbonate-facies BIFs were intercepted by drill cores in the Pilar gold deposit in the NE sector of the Quadrilátero Ferrífero (QF), Brazil, located in the Neoarchean Rio das Velhas greenstone belt. These rocks are interbedded with mafic and ultramafic metavolcanic rocks and carbonaceous phyllites. In light of the potential to reconstruct paleodepositional evidence indicative of the Earth's atmospheric redox history based on this stratigraphy, we have considered specific proxies from geological and geochemical observations. Pilar BIFs geochemistry exhibits positive anomalies of La, Eu, and Y, indicating characteristics inherited from seawater and high-temperature hydrothermal fluids. In addition, a superchondritic Y/Ho ratio further supports the influence of seawater. The signatures of the major elements Al2O3 and other immobile elements typical of detrital sediments corroborate the interpretation that these rocks were deposited in a deep marine environment with low clastic influence. Furthermore, negative Ce/Ce*SN anomalies in some sections of the Pilar BIF indicate limited oxygen availability which, together with Mo, U, V, and Zn trace-element enrichment factors, indicate deposition under suboxic/euxinic conditions. This research, together with other similar BIF data from the NW QF provide new insights into the paleoenvironmental conditions prevailing during the formation of the Archean volcano sedimentary basins that compose the southern São Francisco craton (SFC).

An efficient approach to detect and segment underwater images using Swin Transformer

In managing the fish environment and underwater ecosystem, there's been a big shift from old-generational schoolings, hands-on methods to high-technologies, automatic ways of doing things, because of some clever computer technology, using a type of Artificial Intelligence smartness known as Convolutional Neural Networks, or CNNs in short. These smart systems help deal with the tricky task of keeping tabs on where fish stay out in deeper underwater, particularly when it's hard to see underwater and when the fish are all over the place. There are some pretty good tools and techniques already out there, like DPANet and a few others with names like PIFS-Net, EFS-Net, and MFAS-Net, which have been helping a bunch of researches and developments for underwater ecosystem. But Deeper water environment still needs a newer and better way to get the tasks done. So, to answer this major question, this hybrid architecture rolls out a new combination that takes the best bits of transformer architecture known as Swin Transformer and another mechanism known as ConvMixer, making it in a form of SwinUNet Architecture. This Swin Transformer is well defined at picking up on the spatial information from underwater deeper images in our case, which is a key point to be highlighted in really getting the fish's niche turf and enquiring their ecosystem. And when the underwater turns misty, the specialized implementation of ConvMixer modules incorporated with Swin Transformer increases its ability to sort out the fish from the rest of the underwater world. And this makes it to perform even more better compared with the existing state of arts model, even under Modern Underwater Machine Vision System conditions. This model even over takes to utilization of Few-Shot Learning model for training it in this lesser Underwater Images, with its capability of identifying the patterns and differentiations in both larger and smaller class objects in the given ground truth image. In this new approach, the paper combines the smart focusing methods with a way to blend different signals to better mIoU score, making it super useful for having a deeper understanding on fish-ecosystem and also their underwater ecosystem. While comparing it with the pre-existing state of arts model and the booming Image Segmentation models (YOLO v8, Pix 2 Pix GAN model, Auto Encoders, UNet), the hybrid approach outperformed the existing model results on this Semantic Segmentation for Underwater Imagery (SUIM) dataset, which is been disclosed in the further sections below.

Characteristics and sedimentary evolution of late Ediacaran-early Cambrian microbial carbonates, chert, and phosphorite in South China

ABSTRACT The Ediacaran-Cambrian (E-C) transition period witnessed one of the most important environmental changes in Earth’s history. The western margin of the South China Block (SCB), a shallow-water environment, shows a complete sedimentary record of the E-C transition. Section surveys revealed that dolostone, microbial carbonate, chert, and phosphorite predominantly compose the lithologies of the western margin of the SCB during the E-C transition. Petrological analysis indicates that microbial carbonates in this region exhibit stromatolitic, thrombolytic, cavitated, and sporadic microbial structures. Microbial carbonates with stromatolitic, thrombolytic/cavitated, and sporadic structures correspond to strong, moderate, and weak hydrodynamic conditions, respectively. Microcrystalline dolomites crystallize during the syngenesis stage, while meso- to macrocrystalline and sparry dolomites develop during the burial diagenesis stage. Analysis of major elements and rare earth elements anomalies (δCe: 0.580 ~ 0.753; δEu: 1.234 ~ 1.433) suggests that the siliceous component originates from hot-water sources and is transported into shallow-water environments by upwelling. The absence of a δEu anomaly and the morphology of peloids indicate that the phosphatic component is primarily influenced by biological activity and upwelling. During the Tongwan Movement (545–535 Ma) in the E-C transition period, cyclical upwelling transported increased amounts of deep-source materials into shallow platform waters, leading to higher concentrations of siliceous components and widespread microbial mortality. Following the widespread microbial mortality, the phosphatic component became enriched in deep-water environments. Subsequently, the upwelling transported siliceous- and phosphatic-rich fluids back into the shallow-water environments. The phosphatic component was ultimately assimilated by small shelly fauna and deposited in the phosphatic-rich strata of the early Cambrian period. This study elucidates the origins of complex lithological compositions and the sedimentary evolution model in shallow water environments of the E-C transition period in western SCB, offering evidence for global environmental changes during this period.

North-south discrepancy in the contributors to CB153 accumulation in the deep water of the Sea of Japan

The deep-water environment and its ecosystem are becoming the ultimate sinks for Polychlorinated Biphenyls (PCBs). A three-dimensional hydrodynamic-ecosystem-PCB coupled model was applied to the Sea of Japan (SoJ), where deep water is isolated from the surrounding oceans, to elucidate the accumulation processes of CB153 and assess the contributions of physical and biological processes to the accumulation. We suggest that the dissolved CB153 concentration formed a three-layer vertical structure in the SoJ: the highest concentration is in the intermediate layer (100–600 m), followed by those in the deep (600 m to the bottom) and surface layers (0–100 m). Different accumulation mechanisms in the northern and southern SoJ were discovered. The oceanic biological pump enhances the accumulation in the northern SoJ by taking CB153 out of the thermocline in summer and contributes 70 % to the accumulation in the intermediate layer; while the vertical advection contributes 70 % to the accumulation in the intermediate and deep layer in the southern SoJ.

First Successful Wireline Stress Testing in a Gas Hydrate Reservoir in the Hyuganada Sea, Japan

This study presents a stress testing operation conducted using a wireline formation tester in a newly discovered gas hydrate prospect located offshore in Japan. The campaign, which spanned from December 2021 to January 2022, involved drilling a well using logging-while-drilling technology. Subsequently, wireline formation testing and stress testing were successfully conducted at three different depths within a gas hydrate-concentrated zone. The testing was accomplished in a single riserless descent, with the primary goal of obtaining crucial data such as mobility, formation pressure, and fracture gradient for one of the prospects. This operation marked the first stress testing job performed with dual packers in an open water and deepwater environment specifically for gas hydrate reservoirs. The study also provides a comprehensive interpretation of the data gathered during the operation. Moreover, it evaluates various properties such as formation mobility, formation pressure, initial breakdown pressure, closure pressure, fracture propagation pressure, and instantaneous shut-in pressure.

Experimental research on dynamic responses and hydrodynamic pressures of deep-water bridge piers under seismic and wave actions

Earthquakes and extreme waves pose significant threats to the safety of offshore bridges, particularly in deep-water environments. The temporal sequence of earthquakes and waves and the specific type of earthquake are critical factors that contribute to the potential risks involved. This study aimed to fill a key knowledge gap by conducting a comprehensive series of physical tests on a deep-water bridge pier at a scale factor of 1:30. White noise tests, shaking table tests, wavemaker tests, and combined shaking table and wavemaker tests were carried out. Near-field pulsed earthquakes, far-field long-period earthquakes and earthquake-wave phase differences were examined in the tests. The test results indicate that the presence of water has a noticeable impact on the natural frequency, particularly the 2nd-order frequency, of bridge piers, which may significantly influence the dynamic responses of high bridge piers. The effects of water–pier interactions are further intensified by seismic actions such as the pulsed Loma Prieta and long-period Chi-Chi earthquakes. Moreover, the earthquake-induced hydrodynamic pressures on the upstream and downstream faces of the pier are nearly identical, whereas there is a notable difference when the pressures are caused by incident waves. The magnitude of the combined earthquake and wave responses in relation to the individual responses is influenced by the earthquake–wave phase differences, and the combined responses are less than the sum of the individual responses.

Free vibration analysis of fiber-reinforced composite multilayer cylindrical shells under hydrostatic pressure

With the development and application of composite materials in deepwater submersibles, the influence of high external pressure from deepwater environments on the vibration characteristics of composite pressure-resistant cylindrical shells cannot be ignored. In this paper, the free vibration characteristics of prestressed composite multilayer shells are methodically examined by establishing partial differential equations based on the three-dimensional elasticity theory. To solve these equations, the state-space technique and double Fourier series expansion are employed to transform them into state-space ordinary differential equations. These equations are utilized to analyze vibration problems of simply supported composite multilayer cylindrical shells with arbitrary layered angles. The initial stress equilibrium equation is solved to determine the prestress induced by the hydrostatic pressure. This overcomes the limitation of membrane stress and considers non-uniform distributions of radial and interlaminar prestresses. The proposed theoretical model and solution strategies are validated by comparing with theoretical and experimental results from the existing literature and the finite element method. Additionally, the present investigation reveals that the natural frequencies of thick shells can be calculated more accurately using the prestress derived by the proposed approach, especially subjected to noticeable hydrostatic pressure. Finally, the performed investigations indicate that the circumferential prestressing has a more pronounced effect on the shell's natural frequencies than axial prestressing.

Technological innovations and optimized work methods in subsea maintenance and production

Subsea maintenance and production represent critical aspects of offshore operations, vital for sustaining energy production and ensuring operational efficiency. However, these endeavors face numerous challenges, including the complexities of deepwater environments, harsh weather conditions, and the high costs associated with traditional maintenance methods. To address these challenges, this paper explores the integration of technological innovations and optimized work methods in subsea operations. Technological innovations play a pivotal role in revolutionizing subsea maintenance and production. Remote monitoring and control systems enable real-time data collection and decision-making, enhancing operational visibility and efficiency. Autonomous underwater vehicles (AUVs) offer the capability to conduct inspections and repairs in remote and hazardous environments, reducing human intervention and associated risks. Robotics and automation further streamline maintenance tasks, improving accuracy and reducing downtime. Advanced materials and coatings enhance equipment durability and corrosion resistance, prolonging asset lifecycles and reducing maintenance requirements. In parallel, optimized work methods offer strategic approaches to enhance subsea operations' effectiveness. Predictive maintenance strategies leverage data analytics and machine learning to anticipate equipment failures, enabling proactive interventions and minimizing downtime. Condition-based monitoring facilitates real-time assessment of asset health, enabling timely maintenance interventions and cost savings. Integrated asset management systems provide holistic insights into asset performance and facilitate informed decision-making. Lean operations and continuous improvement methodologies further optimize workflows, driving operational excellence and cost efficiency. Through case studies and industry examples, this paper highlights the successful implementation of technological innovations and optimized work methods in subsea maintenance and production. Furthermore, it explores future trends, regulatory considerations, and the importance of industry collaborations in shaping the future of subsea operations. Ultimately, the integration of these approaches offers a pathway towards enhanced operational efficiency, reduced costs, and sustainable subsea operations. Keywords: Technological Innovations, Optimized Work Methods, Subsea Maintenance and Production.

Numerical Study of Supersonic Jet Characteristics of Underwater Solid Rocket Engine

The structure of the rocket supersonic jet changes periodically when the solid rocket engines are ignited underwater. To investigate the flowfield structure and thrust characteristics of underwater gas jets emanating from solid rocket engines, this study establishes a numerical model for the multiphase flow of underwater jets based on the volume of fluid and realizable k-ε models. The effectiveness of the model is validated through comparison with experimental data. Subsequently, numerical simulations of tail jets from solid rocket engines are conducted at different water depths. The results indicate that during the underwater operation of solid rocket engines, the tail jet undergoes periodic processes such as expansion, constriction, rupture, and recoil. At larger depths, the environmental pressure exerts a more significant effect on the gas jet, thus resulting in a slower axial development of gas bubbles but more significant periodic evolution processes. Unlike the case in air, the thrust of solid rocket engines oscillates significantly when ignited underwater. In deeper water environments, the engine thrust presents a smaller oscillation amplitude. The findings of this study provide a theoretical basis for the design of solid rocket engines ignited underwater.

Intelligent Completion Enables Zonal Isolation Offshore Malaysia

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper IPTC 22882, “Advancement of Openhole Gravel Pack and Zonal Isolation With Selective Intelligent Completion in Deepwater Malaysia,” by Elvy Samuel, SPE, Noppanan Nopsiri, and Lee Chan Fong, PTTEP, et al. The paper has not been peer reviewed. Copyright 2023 International Petroleum Technology Conference. _ As fields mature, drilling and completion design and execution for infill development become more challenging. In a deepwater environment, one strategy is to target several reservoir packages in a single wellbore. This technique frequently presents technical challenges, however, because penetrating different zones requires active reservoir management, an allowance for zonal isolation, and an adequate response to potential crossflow. The complete paper presents a completion strategy implemented in an intelligent well completed in the Malaysian deepwater Block K. Introduction The SNP Field is 125 km offshore Sabah in approximately 1350–1400 m water depth. The field crosses the boundary between Block K and Block G, approximately 15 km from the Kikeh floating production, storage, and offloading (FPSO) facility. The field commenced Phase 1 in 2011 with the completion of nine oil producers as openhole gravel packs (OHGPs) and five water injectors with expandable sand screens at the sandface. Phase 2 development, partially covered in the complete paper, commenced in the third quarter of 2021 with three standard oil producers and one smart producer well. All SNP Phase 2 wells were completed as OHGPs targeting various sand reservoirs in a common pressure regime. The well discussed in the complete paper addressed subsurface uncertainties related to depth and the pressure differential between the upper zone (UZ) and the lower zone (LZ) and the isolation requirements of the middle zone (MZ) by implementing an intelligent completion architecture with an OHGP with zonal isolation on the sandface. The flow diversion between the producer zones would be achieved through the deployment of an intermediate completion coupled with an intelligent completion architecture in the upper completion. The well was placed on production in the first quarter of 2022 to the Kikeh FPSO, achieving the targeted rates solids-free. Gravel-Pack Design In this field, the fracture pressure window is marginal, suggesting that a conventional OHGP approach would be challenging. Adding to this complexity is the zonal-isolation requirement. To achieve the objective of complete openhole (OH) coverage and to enable zonal isolation simultaneously, shunt-tube technology was identified as critical. The selection of shunt-tube technology allows the following achievements: - Premature screenout mitigation, because the technique is a proven system that enables the slurry to bypass any restriction in the OH/screen annulus - Zonal-isolation capabilities by combining shunted sand screens and OH mechanical packers with selective shunt-tube isolation capabilities - Application of diverter valves, crucial in fields with marginal fracture pressure windows