Deepwater Platforms Research Articles

Satellite NO2 Trends and Hotspots Over Offshore Oil and Gas Operations in the Gulf of Mexico

AbstractThe Outer Continental Shelf of the Gulf of Mexico (GOM) is populated with numerous oil and natural gas (ONG) platforms which produce NOx (NOx = NO + NO2), a major component of air pollution. The Bureau of Ocean Energy Management (BOEM) is mandated to ensure that the air quality of coastal states is not degraded by these emissions. As part of a NASA‐BOEM collaboration, we conducted a satellite data‐based analysis of nitrogen dioxide (NO2) patterns and trends in the GOM. Data from the OMI and TROPOMI sensors were used to obtain 18+ year records of tropospheric column (TrC) NO2 in three GOM regions: (a) Houston urban area, (b) near shore area off the Louisiana coast, and a (c) deepwater area off the Louisiana coast. The 2004–2022 time series show a decreasing trend for the urban (−0.027 DU/decade) and near shore (−0.0022 DU/decade) areas, and an increasing trend (0.0019 DU/decade) for the deepwater area. MERRA‐2 wind and TROPOMI NO2 data were used to reveal several NO2 hotspots (up to 25% above background values) under calm wind conditions near individual platforms. The NO2 signals from these deepwater platforms and the high density of shallow water platforms closer to shore were confirmed by TrC NO2 anomalies of up to 10%, taking into account the monthly TrC NO2 climatology over the GOM. The results presented in this study establish a baseline for future estimates of emissions from the ONG hotspots and provide a methodology for analyzing NO2 measurements from the new geostationary TEMPO instrument.

The dynamic analysis of fixed deep-water platform

The industrial progress is closely related with active using of hydrocarbons more than half of reserves of which lie in rock formations beneath seabed or ocean floor. For oil production at the great depth of immersion oil production fixed platforms are used most often. But using of such technological structures is not limited only to interest of oil and natural gas industry whereas they are important for navigation and military purposes. Offshore fixed platforms are exposed to effects of a high seismicity, wind, waves, strong undercurrents and an impulse impact during the movement of ice fields especially when exploitation in northern seas. The impact of different factors on the value of the period of natural oscillations ofthe offshore fixed deep-water ice-resistant platform with the depth of immersion 120 m that rests on the pile foundation was researched. Two discrete idealized models of the platform were used for the analysis: the first model that was implemented without taking into account the flexibility of the foundation and the second model where the flexibility of the pile foundation and the action of ground foundation were taking into account by the addition of elastic links that simulate the elastic connection between joints. Also, impacts of the connected mass of water media that was modeled in the form of additional distributed joints mass and the impact of the ice field that was modeled by the addition of additional links were investigated. The analysis showsthat values of periods of natural oscillations form increase by 8-20% when the flexibility of the pile foundation was taken into account; increase by 9-100% when the impact of the connected mass of water media was taken into account; decrease by 9-100% when the impact of the ice field and water media were taken into accountthat is significant when analyzing of stress-strain state of members of the structure.

Predicting motions of deepwater platform based on the inverse reconstruction of environmental loads

In hybrid model testing technique, model tests are primarily used to verify numerical models which is used to predict the responses of full-depth systems. However, hybrid model testing method based on potential flow theory highly rely on the accuracy of mathematical model, facing challenges in accurately predicting full-depth responses with viscous effects, such as flow-induced motion. To solve the problem, a method for predicting motions of full-depth system is proposed based on the inverse reconstruction of the environmental loads from the truncated model test, considering viscous and nonlinear effects on platform. To validate the method, a series of model tests were conducted for a semi-submersible platform in head seas using both truncated and full-depth mooring systems to validate the method. The environmental loads could be extracted accurately via the inverse reconstruction method under different environmental conditions, including 100-year-return-period wave-only, current-only, coupled wave, wind, and current conditions. The results of time history, statistics, and power distribution show that the proposed method has better performance than conventional method of hybrid model test in situations where viscous effects are obvious.

Carbonate sedimentation and reservoirs associated with a volcanic mound in an open-marine, deep-water, drowned platform setting, Elaine field area, Upper Cretaceous Anacacho Formation, South Texas U.S.A.

In the Upper Cretaceous Balcones Igneous Province in South and Central Texas, numerous small volcanoes developed during Austin Chalk and Anacacho deposition that are similar to the recent Surtsey volcano offshore of Iceland. The volcanoes formed topographic highs on the deep-water (500–900 ft [150–275 m]), earlier-drowned Comanche Platform. The Elaine field in South Texas is associated with one of these relict volcanic highs and integration of a 3D-seismic dataset and cores permitted a detailed analysis of the deeper-water carbonate depositional systems of the field and associated carbonate reservoir development. This reservoir description extends the understanding of petroleum systems associated with relict, open-marine, deep-water, volcanic highs. In the shallow water at the top of the volcanic topographic highs, a carbonate factory developed that produced coarser-grained carbonate sediments that sourced the deeper-water flanks and toe-of-slope of the mound. Finer-grained carbonate chalk was deposited in the open-marine, deep-water environment adjacent to the volcanic mound. The coarser-grained carbonate sediments sourced from the mound top were transported downslope by gravity-flow processes that formed debrites and hyperconcentrated density-flow deposits. The gravity-flow deposits are composed of a mixture of shallow- and open-marine, deep-water biota indicating they are not shallow-water deposits, but are deeper-water mound-flank and toe-of-slope deposits.In the Anacacho Elaine field, the coarser-grained carbonates (i.e., skeletal packstones and grainstones) associated with the volcanic mound are the oil-producing reservoirs. The Elaine volcanic mound itself is tight and not productive. The Anacacho chalk immediately above the mound are also tight and form the top seal for the Elaine field.Associated with the relict volcanic mounds in the Balcones Igneous Province are a spectrum of carbonate plays. The relict volcano can be a reservoir, but not all the relict volcanic mounds are porous. The coarser-grain carbonates on the top, flanks, and at the base of the volcanic mounds are reservoirs in the area of the Balcones Igneous Province. The chalks deposited penecontemporaneously on the open-marine, deep-water platform can also be tight carbonate reservoirs.

Motion characteristics of vertically loaded anchor during drag embedment in layered clay

As a widely used taut-wire mooring system for deepwater platforms, the Vertically Loaded Anchor (VLA) has better performance in bearing capacity, angle adaptability, and deepwater installation than other systems. However, the installation process of the VLA and its motion characteristics are significantly impacted by multi-layered seabed soil. In this paper, the coupled Eulerian‒Lagrangian (CEL) large deformation finite element analysis method has been applied to analyse the continuous penetration of a VLA in nonuniform clay with an interbedded stiff layer. A detailed parametric study has been carried out to explore the trajectory, drag angle, movement direction and drag force of the VLA in layered clay with different embedded depths, thicknesses and undrained shear strength of the stiff layer. The CEL numerical analysis results have been validated by comparison with the analytical solutions from the inverse catenary equation. Excellent agreement has been obtained between the results from the CEL analyses and the analytical solutions. The stiff layer leads to concave and convex shapes on the trend lines of the movement direction angle and drag forces, respectively. The embedded depth of the stiff layer determines where the concave and convex shapes appear on the trend lines, while the thickness affects the sizes of the openings of the shapes. The most decisive parameter, an abrupt variation in the undrained shear strength, causes predominant rotation at the interface of layered clay. It diminishes the final embedment depth and ultimate stable drag force, meaning that the bearing capacity of the VLA severely declined in layered clay.

Real-time prediction of the mechanical behavior of suction caisson during installation process using GA-BP neural network

Due to the short construction period, convenient transportation and strong geological adaptability, the suction caisson has received more and more attention in offshore geotechnical foundation engineering associated with oil and gas production platforms. A good understanding of the mechanical behaviors of soils, such as real-time effective stress and settlement, around the suction caisson during its installation is important for analyzing the stability and loading capacity of the platforms in deep water. The objective of this research is to develop a numerical model for predicting the mechanical behavior of soils around the suction caisson during installation based on the data including real-time settlement and effective stress produced from the centrifuge tests in the literature by using the genetic algorithm-back propagation (GA-BP) neural network method. Furthermore, the nonlinear relationship among the settlement, penetration pressure, effective stress, and suction required during the installation is thoroughly investigated. It is found that, compared with the experimental results, the relative error of the prediction results from the proposed model is −0.3%∼1.4% for settlement, 0.8%∼2.3% for effective lateral stress in a single clay layer, and −2.5%∼4.5% for normalized required suction in multilayered soils at the final stage. It can be concluded that the GA-BP neural network method can be used to predict the real-time hydromechanical behavior of the caisson foundation during the installation process in terms of efficiency and accuracy.

Temporal and Spatial Relationships of Yellowfin Tuna to Deepwater Petroleum Platforms in the Northern Gulf of Mexico

AbstractIn 2006–2007, 110 Yellowfin Tuna Thunnus albacares were tagged with acoustic transmitters near deepwater oil platforms and one drillship in the northern Gulf of Mexico off the Mississippi River delta to determine the extent to which platforms act as fish aggregating devices (FADs). Vemco acoustic receivers were installed on six deepwater platforms to detect the presence of tagged individuals. Five of 12 Yellowfin Tuna captured in 2006 were detected in 2007, demonstrating multi‐year presence in the region. Ninety Yellowfin Tuna were detected in 2007, resulting in 221 platform residencies and 32 single detections. Duration of residence at a platform was positively correlated with the platform's depth, and the number of transitions decreased with platform‐to‐platform distance. In total, 109 movements between platforms by 46 (51%) different individuals were detected, traveling distances of up to 98.2 km. Yellowfin Tuna displayed interactions with deepwater platforms in the northern Gulf of Mexico similar to their interactions with FADs and other studied geological features, by way of aggregating or using them as meeting points, landmarks, and stopovers within a movement corridor. The large number of oil and gas platforms located in the northern Gulf of Mexico may have a significant effect on distribution, retention, and migration of Yellowfin Tuna populations in this area of the gulf.

A Hybrid Taguchi Particle Swarm Optimization Algorithm for Reactive Power Optimization of Deep-Water Semi-Submersible Platforms with New Energy Sources

In order to realize the sustainable development of energy, the combination of new energy power generation technology and the traditional offshore platform has excellent research prospects. The access to new energy sources can provide a powerful supplement to the power grid of the offshore platform, but will also create new challenges for the planning, operation, and control of the power grid of the platform; hence, it is very important to optimize the reactive power of the offshore platform with new study, a mathematical model was first built for the reactive power optimization of offshore platform power systems with new energy sources, and the Taguchi method was then used to optimize the parameters and population of particle swarm optimization, thereby addressing a defect in particle swarm optimization, namely, that it can easily fall into local optimal solutions. Finally, the algorithm proposed in this paper was applied to solve the reactive power optimization problem of the offshore platform power system with new energy sources. The experimental results show that the proposed algorithm has stronger optimization ability, reduces the system active power loss to the greatest extent, and improves the voltage quality. These results provide theoretical support for the practical application and optimization of the deep-water semi-submersible production platform integrated with new energy sources.

Nonlinear Response Prediction of Spar Platform in Deep Water Using an Artificial Neural Network

The finite element method (FEM) is an essential method for predicting the response of the spar platform considering all nonlinear variables. Although FEM is an extremely laborious and time-consuming process for predicting platform responses using hydrodynamic loads, artificial neural networks (ANNs) can predict the response quickly, as required for platform management to either linger or stop the production of oil and gas. The application of ANN approaches to estimate the wave height and period from the expected wind forces is investigated in this paper. The ANN model can also predict the nonlinear responses of the spar platform subjected to the structural parameter as well as the wave height and wave period. The backpropagation technique depletes feed-forward neural networks, allowing the network to be trained. Following the formation of the neural network, rapid reactions from a freshly anticipated wind force are obtained. The results are validated via a comparison with results from a conventional finite element analysis. The findings demonstrate that the artificial neural network (ANN) technique is effective and is able to significantly reduce the required time to make predictions when compared to the conventional FEM.

An Efficient Monte-Carlo Simulation for the Dynamic Reliability Analysis of Jacket Platforms Subjected to Random Wave Loads

The growing demand for the application of jacket platforms in deep water requires more attention on the assessment of structural reliability. This paper is devoted to the dynamic reliability analysis of jacket platforms subjected to random wave loads with the Monte-Carlo simulation (MCS), in which a sample size of the order of magnitude of 104 to 105 for repeated time–history analyses is required for small failure probability problems, and a duration time up to three hours needs to be considered in the time–history analyses for a specific sea condition. To tackle the difficulty involved in the MCS, the explicit time-domain method (ETDM) is used for the required time–history analyses of jacket platforms, in which truncated explicit expressions of critical responses with regards to the contributing loading terms are first established and then used for numerous repeated sample analyses. The use of ETDM greatly enhances the computational efficiency of MCS, making it feasible for the dynamic reliability analysis of jacket platforms under random wave loads. A jacket platform with 11,688 degrees of freedom was analyzed for the evaluation of dynamic reliability under a given sea condition, indicating the accuracy and efficiency of the present approach and its feasibility to practical structures.

Static Analysis of Oil Platforms in Deep Water using Dynamic Load Stations. (Dept C (Structural ))

Static Analysis of Oil Platforms in Deep Water using Dynamic Load Stations. (Dept C (Structural ))

Technology of steel jackets load-out in deep-water offshore platforms from the barge

Currently, great attention is paid to the development issue of the shelf’s fuel and energy resources foremost in the oil-gas fields of the Caspian Sea. The problem solution requires the studying of great majority of scientific-technical issues. One of the significant problems is the lead-out of steel jacket from the offshore platform as a major element of oil-gas field hydro-technical facilities meant for the operation in the deep water. The calculations for the execution of operations with steel jacket of deep stationary platform from the block with the detailed chara- cteristics by the mass and gravity center coordinates alongside line data have been carried out with “SACS” and “STAAD.PRO” software programs. The steel jacket is pushed astern with the push-pull equipment on the barge. Due to the shift of gravity centre the jacket changes the trim in the stern. Through the elevation of trim angle brought in alignment with the friction ration between the jacket and barge, the jacket slides further itself. Herewith, the trim increases until the gravity centre of steel jacket on the barge is not in alignment with rotation centre of the large rocker arms. The studies helped to fix the position of the jacket’s gravity centre from the aft perpendicular, the trim moment, the trim of the barge, the draft with the bow and stern and the trim angle as well.

Digital Deepwater Imaginaries in Brenda Longfellow's Offshore

This essay draws together digital humanities, science and technology studies, and energy culture to theorize the extractive site of the offshore in contemporary digital media. Elaborating on anthropological research that emphasizes the offshore industry's modularity, this essay turns to filmmaker Brenda Longfellow's interactive digital feature Offshore (2012) to examine how immersive user-guided media disrupt the modular logic of deepwater extraction. I argue that the postapocalyptic aesthetic of Offshore, set in an abandoned deepwater platform, works in concert with the text's interactive form to install affects of ambivalence, anxiety, and uncertainty that unsettle the habitus of tough-oil culture.

Study of a TLP motions and forces using 3D source technique

The production and consumption of oil and other petroleum products have been increasing rapidly over the years, which led to the scarcity of easily retrieved oil due to urbanization. As a result, oil producers are motivated to go to deeper ocean to extract oil and other resources.Offshore platforms in deep water like TLPs are used for exploration of oil and gas from under Seabed and processing. But it is challenging to design precisely such type of giant structure in deep sea as it experiences huge forces, motion and other environmental loads which are non-linear, need sophisticated solution techniques and expensive to apply. In the present study wave exciting forces and motions of free floating TLP are carried out in frequency domain analysis using three dimensional source distribution techniques within the scope of linear wave theory where six degrees of freedom have been considered. The same geometrical data are used as an input to HydroStar, which is based on linear wave theory. Results obtained from both the programs are compared which shows a good agreement and also validated with the published results. Comparison of heave motion with and without tether are illustrated where it can be easily understood the effect of tendon. Forces and motions prediction of TLP is emphasized which has been done precisely in the present work and in future it will help us to design the TLPs as well as the tendon system in deep sea. Finally, a number of recommendations have been made for further research based on the present study.

Coral reefs and growth dynamics of a low-angle Carboniferous platform: Records from Tianlin, southern China

Metazoan reef building receded globally during the Carboniferous after the Late Devonian extinction events. Shallow-water bioconstructions were generally small and scarce, and corals played a minor role in their construction. However, in southern China, one large (50 m high) and three small (6–16 m high) coral reefs, dating from the Late Viséan–Serpukhovian, have recently been discovered in two localities in Guangxi. To understand the occurrence of these coral reefs and to constrain the factors that controlled their growth, three sections around Langping (Guangxi) were measured, and selected samples were analysed using petrography, biostratigraphy, and chemostratigraphy. The depositional environment of these exceptional Mississippian reefs was interpreted as a low angle platform (1–2.5°), recording oligotrophic conditions and normal salinity. The three small reefs have grown around the fair-weather wave-base, whereas the large coral reef has grown in a deeper environment, between the fair-weather and storm wave-base.During Carboniferous, the global temporal reef distribution can be partly ascribed to paleoclimate changes. However, in southern China, the growth of extended Mississippian coral reefs is restricted to a short time window, the Late Viséan-Serpukhovian, which coincides with high amplitude and high frequency sea-level fluctuations most likely related to glacial pulses. Recent studies revealed that several rugose coral species survived the mid Carboniferous glaciation event thanks to the persistence of warm water ocean currents maintaining tropical conditions on the platform. Due to the scarcity of extended coral reefs elsewhere, it cannot be excluded that Tianlin provided an ecological refuge for corals, related to oceanic currents. Another potential favorable factor could be the mid ramp depositional setting. The deep-water platform areas could potentially provide more stable conditions, less affected by global stress events. However, the ‘deep reef refugia’ hypothesis remains debatable as only very few studies have explored its validity at the community level. Even if the causes of the occurrence of an extended coral reef in southern China cannot be fully constrained, the existence of this large coral framework in the Late Viséan-Serpukhovian provides additional evidence that coral communities did build reefs after the Late Devonian extinction events.

Guadalupian (Middle Permian) ocean redox evolution in South China and its implications for mass extinction

The Guadalupian mass extinction was a long-term biocrisis that started in the early Guadalupian Epoch (Permian Period). Many studies of the causes of the extinction have focused on the late Guadalupian, although the entire Guadalupian should be studied to address its origins. The selective nature of the species removed during the Guadalupian extinction also remains a puzzle. Here, we present pyrite framboid size distributions, pyrite-sulfur isotopic compositions, and C-N-S profiles for the entire Guadalupian from South China to develop a record of ocean redox evolution to help understand the selective extinction. Our results indicate that euxinia was mostly persistent in the deep-water platform basin throughout the Guadalupian, which triggered long-term Early and Middle Guadalupian shallow-water dysoxia and frequent episodic Late Guadalupian euxinia events that resulted in a gradual long-term Early and Middle Guadalupian diversity decrease and selective Late Guadalupian extinction. The combined effect of euxinia and global regression led to selective extinction of taxa that had weakly buffered respiratory physiology and high growth efficiency, such as brachiopods, large fusulinids, and giant bivalves.

Research on facility layout optimization algorithm of deep-water semi-submersible drilling platform

We aimed to create a facility layout design of semi-submersible drilling platform (DSDP) with performance constraints. The Boltzmann survival mechanism of simulated annealing algorithm was introduced into the replacement strategy of genetic algorithm to form an improved genetic algorithm called genetic and simulated annealing algorithm (GASA). The new algorithm alleviates the “combination explosion” and premature convergence of the traditional genetic algorithm. The layout problem of DSDP is efficiently solved by using this new algorithm. When the number of layout objects increases, GASA’s performance is better than that of the genetic algorithm.

A Generalized Correlation for Predicting Ethane, Propane, and Isobutane Hydrates Equilibrium Data in Pure Water and Aqueous Salt Solutions.

Hydrate formation can cause serious problems in hydrocarbon exploration, production, and transportation, especially in deepwater environments. Hydrate‐related problems affects the integrity of the deepwater platforms, leads to equipment blockages, and also increases operational costs. In order to solve these problems, salts are used as thermodynamic inhibitors and also mixed with the drilling fluids in most drilling processes. A comprehensive understanding of hydrate formation in aqueous salt solutions is vital to overcome these problems. Statistical thermodynamic models are commonly used to predict hydrate formation conditions in different aqueous solutions. However, these models involve rigorous computations and are restricted to certain conditions. They give inaccurate predictions of hydrate equilibrium conditions for high‐temperature, high‐pressure, and high‐salinity systems. Therefore, it is paramount to develop a simple‐to‐use and reliable prediction tool. In this work, an empirical correlation is developed and successfully used to predict the equilibrium conditions of ethane, propane, and isobutane hydrates in pure water and aqueous solutions of sodium chloride, potassium chloride, calcium chloride, and magnesium chloride. Experimental data on hydrate formation conditions for these components are regressed and a generalized correlation is obtained. The predictions in this work show excellent agreement with all the experimental data in the literature.

Nonlinear Time-Domain Theory for the Simulation of Moored Floating Body Motion

Nonlinear wave loads can induce low-frequency and high-frequency resonance motions of a moored platform in deep water. For the analysis of the nonlinear response of an offshore platform under the action of irregular waves, the most widely used method in practice is the Cummins method, in which the second-order exciting forces in the time domain are computed by a two-term Volterra series model based on incident waves, first-order body motion response, and quadratic transfer functions (QTFs). QTFs are bichromatic waves acting on a body and are computed in the frequency domain in advance. For moving bodies, QTFs are related to the first-order body response, which is to be determined in the simulation process of body motion response but is unknown in the computation procedure of QTFs. In solving this problem, Teng and Cong (2017) proposed a method to divide the QTFs into different components, which are unrelated to the body response. With the application of the new QTF components, a modified Cummins method can be developed for the simulation of the nonlinear response of a moored floating platform. This paper presents a review of the theory.

Hybrid Parabolic Interpolation – Artificial Neural Network Method (HPI-ANNM) for long-term extreme response estimation of steel risers

This paper presents a computer efficient approach to evaluate the multi-dimensional integral found in the evaluation of the long-term extreme response of marine structures. The proposed method is a hybrid combination of two numerical procedures. The first one consists of a parabolic interpolation scheme used to obtain the statistical parameters describing the short-term peaks probability distribution of the time-series responses, designated as PIM (Parabolic Interpolation Method), which reduces the total number of short-term structural analyses. The second one is an Artificial Neural Network-based surrogate model which is used to obtain long response time histories based on short finite element-based simulations. The approach is named as HPI-ANNM (Hybrid Parabolic Interpolation – Artificial Neural Network Method). The efficiency and accuracy of the proposed hybrid method is compared with the complete long-term integration method in the analysis of 100-yr characteristic values of cross-section utilization ratios of a Steel Catenary Riser (SCR) connected to a semi-submersible platform in deep water.