Offshore Oil Exploitation Research Articles

Exploring source-specific ecological risks of PAHs near oil platforms in the Yellow River Estuary, Bohai Sea

The Yellow River Estuary (YRE) is one of highly remarkable regions profoundly impacted by human activities, with numerous oil platforms dispersed throughout. In this area, offshore oil exploitation may pose significant ecological risks. To comprehensively evaluate the quantitative impacts of oil field exploitation on the marine coastal ecosystem, this study investigated the occurrence, sources, and ecological risks associated with 16 polycyclic aromatic hydrocarbons (PAHs) in seawater and sediment near oil platforms in the YRE. We found that 1) The concentrations of PAHs decreased from the surface seawater to sediments; 2) The ecological risk level of PAHs in seawater exceeded that in sediments; 3) terrestrial sources (combustion), rather than offshore oil drilling activities, significantly influenced regional ecological risks through processes of atmospheric deposition and surface runoff. These findings provide essential data for future estuarine research efforts while supporting mitigation measures aimed at addressing marine environmental pollution related to oil production activities.

A new wake superposition model and its application in collision prevention control of tri-riser array system

In the field of offshore oil exploitation, the compact multi-riser arrangement increases the risk of collision and has an adverse impact on production and the marine environment. The solution to this problem involves accurate motion prediction and collision prevention control under the effect of flow field superposition between risers, but there is little research on this related theory. This paper improves the traditional wake shielding effect model and further proposes a wake shielding superposition effect model for the mutual influence between risers, in order to establish a comprehensive accurate motion control model for tri-riser array system. A solution method is introduced for this model, both vibration and collision analysis are conducted for the system. The study revealed that solely augmenting the spacing inadequately mitigates system collisions, and active control is an inevitable choice. Based on this, this paper further designs an active boundary controller that is easy to implement in engineering, to achieve collaborative collision prevention control for three risers, and verifies its stability. Compared with traditional PD control, the proposed control method exhibits significant superiority, which can effectively reduce vibration amplitude, significantly increase dynamic spacing, and thus effectively prevent collisions between risers.

Effect of Pseudomonas aeruginosa on Corrosion Behavior of X65 Carbon Steel.

X65 pipeline steel is widely used in the field of offshore oil and gas exploitation due to its excellent performance. However, due to the complex environment in the ocean, X65 pipeline steel is faced with a great risk of microbial corrosion failure. Therefore, it is of great significance to study the corrosion mechanism of X65 pipeline steel by microorganisms. In this paper, the corrosion effect of Pseudomonas aeruginosa (P. aeruginosa) secreting phenazine compounds on X65 pipeline steel was studied by the weight loss method, biofilm scanning electron microscopy analysis, surface corrosion morphology observation, electrochemical testing and medium pH test corrosion products. The results showed that the inoculation of P. aeruginosa accelerated the corrosion of X65 steel. After knocking out the phzM and phzS genes that regulate the synthesis of PYO, P. aeruginosa can still produce biofilms on the surface of X65 steel consistent with the morphology of wild-type P. aeruginosa, but the corrosion of X65 steel is significantly reduced. It is proved that PYO plays an important role in the corrosion process of P. aeruginosa on steel.

Cross-sectional layout optimization of the umbilical based on the quasi-physical algorithm

Umbilical, as the lifeline of offshore oil and gas resources exploitation, is composed of a variety of functional components. Due to the differences in physical characteristics of components, the compactness, balance and heat source dispersion of different cross-sectional layouts are also different. So, a multi-objective optimization problem is often encountered. In present study, through a quasi-physical method, different functional components are abstracted as the virtual spheres with different properties lied on a funnel surface. A mathematical description is thereby established according to the interaction force of each two neighbored virtual spheres. Based on that, a new cross-sectional layout optimization formulation is proposed, and solved by using the quasi-physical algorithm. Considering the manufacturing and installation, a layered method is utilized to make the results more in line with the actual needs of the project. Finally, the optimization results of the method are verified by numerical simulation. The verification results show that the cross-sectional layout optimization method based on a quasi-physical algorithm can provide a useful reference for practical engineering design.

Reliability Analysis of a Four-legged Jacket Offshore Platform: A Case Study

Offshore oil and gas exploration and exploitation requires reliable infrastructure. One crucial issue to consider is the reliability of the structure. Structural designs generally use deterministic or fixed values in their calculations. However, the factors involved in the design process may be random variables, such as environmental loads, materials, dimensions, and operational conditions, which may vary. Therefore, when calculating the reliability of a structure, these random variables must be treated with the science of statistics and probability. This research uses probabilistic and statistical methods via the Monte Carlo method to analyze the reliability of offshore jacket structures. The jacket platform is destined for the four-legged Java Sea around Gresik, Indonesia. The research results show that the Jacket platform has a high level of reliability for operating loads of K = 0.9883 and extreme loads of K = 0.9963 based on reliability analysis using the Monte Carlo Simulation method. Although the reliability figure does not exceed 1, this can be taken as a sign that the Jacket platform is declared safe in the analyzed situations. This reliability analysis ensures that the jacket platform is reliable and safe in dealing with the various environmental conditions and loads encountered during its operational life.

Parameter sensitivity analysis of the axial stability for a marine flexible pipe

Marine unbonded flexible pipes serve as the most essential equipment in offshore oil and gas exploration and exploitation. Axial compressive loads during installation or in service in the complex marine environment usually lead to buckling failure. A flexible pipe is a composite structure with multiple functional layers, of which the tensile armor layer plays a key role with regard to the response of the pipe subjected to axial loads. In this paper, a simplified three-dimensional finite element model is developed, focusing on the tensile layer and replacing the carcass layer, pressure sheath layer, and pressure armor layer by a cylindrical rigid body to reduce computational expense. By using this model, the buckling failure modes of the tensile armor layer (in particular the birdcaging phenomenon) are analyzed. Several key parameters that affect the stability of the flexible pipe under axial compression and torsion are emphasized, and their effects on its axial and torsional stiffness are compared and discussed. The results show that both the lay angle of the steel wires and the interlayer friction coefficient have a significant influence on the axial and torsional stiffness of the pipe, whereas the damaged length of the outer sheath has virtually no effect.

Spatial distribution, source apportionment, and assessment of marine water quality parameters in the Bohai Sea, China

A two–year (2020−2021) survey dataset of six water quality parameters (pH, dissolved oxygen (DO), chemical oxygen demand (COD), dissolved inorganic nitrogen (DIN), soluble reactive phosphate (SRP), and petroleum pollutants) was used to investigate their spatial distribution in the Bohai Sea and quantify their potential sources. There were significant differences in spatial distribution of the parameters. High concentrations of COD, DIN and SRP were found in three bays, with terrestrial input being the main pollution source. Phosphorus–limiting conditions were present in the Bohai Sea. High petroleum pollutant concentrations were identified in port areas, offshore oilfields, and adjacent areas. The pH was above the global oceanic average and there were no signs of acidification. The contribution of the mixed terrestrial inputs, maritime transportation, and offshore oil exploitation sources, oceanic and associated biotic sources, and seawater–atmosphere exchange and atmospheric deposition sources to water quality were 63.4 %, 8.0 %, and 28.6 %, respectively.

A hybrid association analysis framework of accident reports for offshore drilling platforms

As the key work unit of offshore oil and gas exploration and exploitation activities, an offshore drilling platform (ODP) integrates high-density equipment and facilities in a relatively narrow area, making it prone to frequent serious accidents under the influence of environmental factors. The mining association rules of the hidden dangers from the accumulated historical accident reports can help find the potential causes of the risks and proactively reduce the risk of accidents and damages. However, due to the professionalism of the corpus linguistics of the offshore oil and gas industry and the complex correlations between multiple named entities, mining valuable information from massive transaction datasets has increasingly become a challenge for academia and industry. To this end, a hybrid association analysis framework for ODPs is proposed in this paper, which is divided into four stages: data preprocessing, information extraction, association rule mining and making a rectification plan. In the key information extraction stage, we propose a three-layer deep learning network based on the BERT-IDCNN-BiLSTM-CRF (BIBC) model, which makes effective use of the semantic information of the context to extract the trituples of the hidden dangers (i.e., equipment, location and phenomenon). Based on the extracted entities, an effective multientity association rule mining algorithm based on hash technology and an inverted itemset (HTApriori) as a variant of Apriori for ODP databases is developed to understand the many-to-one, one-to-many and many-to-many risky causes between the entities. A series of real-world experimental results show that the proposed framework offers more reliable and effective performances of information extraction and association rule mining than the comparison methods. By analyzing the association results, the hidden dangers and their association rules, which occur with some small probability but are critical in ODPs, can be found. This work is helpful in significantly improving the rationality of the rectification plans. In addition, the application results on the CoNLL2003 dataset further prove the generalization performance of the proposed method.

Superhydrophobic DTES-SEP/SiO2@PDMS coated sponge and stainless steel mesh for efficient oil and water separation

The exploitation of offshore oil will inevitably cause oil leakage, which not only affects the ecological environment but also threatens the balance of the marine ecosystem. Therefore, new materials for efficient oil-water separation need to be continuously researched. In this paper, dodecyltriethoxysilane (DTES) was used to hydrophobically modify meerschaolite (SEP) and silicon dioxide (SiO2) nanoparticles. DTES-SEP/SiO2@PDMS coatings were successfully prepared on the surface of sponges and stainless steel meshes by immersion in the presence of polydimethylsiloxane (PDMS). The coating has a water contact angle of up to 153°. It exhibits high wettability. It is worth noting that the adsorption capacity of coated sponges to various oils and organic solvents is 27–77 times their own weight. More importantly, the prepared coatings exhibit excellent stability in strong corrosive solutions. In addition, the mechanical properties of DTES-SEP/SiO2@PDMS coating remain stable after abrasion and peeling. At the same time, the coating shows excellent resistance to grit, methylene blue solution and clay. This research provides a reliable way to achieve efficient oil-water separation.

The economic, social and environmental impacts of offshore oil exploration in Argentina: A critical appraisal

The recent approval of an offshore oil exploration project in Argentina has agitated local communities. It has managed to stop the led to a suspension of the initiative, led to the design and passing of a judicial measure and sparked a public debate about the possible environmental impacts of the project and what implications it has for the sustainability of the oceans. By reviewing the regulatory framework, project approval documents, journalistic notes, and multiple public statements by the actors involved, we sought to reconstruct the conflict's chronology and reflect the problem's multiple edges and visions of the problem. From this work, it was possible to identify the arguments for and against the project, contrast them with scientific evidence generated internationally on offshore oil exploitation, and frame the case study in the debates on the blue economy and the sustainability of the oceans. The results obtained made it possible to identify the main arguments for and against the project, to recognize some achievements and positive results, and to identify horizons towards which the social movement should direct itself to channel the results obtained, the spaces of power gained, and to know what it can demand and receive.

Dynamic analysis of the umbilical cable pull-in operation through J-tube under different wave directions

Pipelines and cables are widely used for transporting oil resources in offshore oil exploitation. J-tubes are a well-known means of placing small-diameter pipeline risers and umbilical connections on offshore platforms. In this paper, OrcaFlex develops a model of an umbilical cable J-tube pull-in installation based on an umbilical cable cross section design. The hydrodynamic response to various wave directions is studied using the lumped mass method. The results show that the longitudinal waves have little effect on the maximum effective tension of the section under water. The transverse waves will cause the cable to vibrate violently in the transverse direction. The mean shear force under the wave direction of 120° is the largest, followed by 60° and 75°, and finally 90° and 105°. In addition to the hydrodynamic response data, the mechanical characteristics of the umbilical cable and the factors that should be considered in the pull-in installation of the J-tube are provided with significance for practical application of engineering.

Research on Performance Test of New Carbon Fiber Nano Antifouling Materials in Offshore Oil Field

Firstly, zinc dioxide and titanium dioxide were prepared from zinc acetate and butyl titanate. A nanometer ZnO/TiO2 film with different morphologies was prepared by doping the two materials. A new type of aluminum alloy base material which can be used in offshore oil exploitation was prepared by using a variety of proportioning methods. The results show that the modification agent can improve the corrosion resistance of the material. The results show that nano-ZnO composite titanium oxide coating has better antifouling and antifouling performance.

Non-destructive testing of high-tenacity polyester sub-ropes for mooring systems

Deepwater mooring systems used in offshore oil exploitation need increasing performance because mechanical solicitations are always higher. Thus, two polyester sub-ropes were studied in this work, aiming for higher-tenacity materials, SFS5202 and UFS8602. Through non-destructive testing based on quasi-static, dynamic, and cyclic loads applied as a percentage of the Minimum Breaking Strength (MBS), the behavior of the underwire for two polyesters and two braiding steps was evaluated. Good performance was obtained in the test concerning low deformation, suggesting that it is a fiber material with high tenacity and elastic modulus, thus becoming adequate for deeper water oil exploitation. Furthermore, UFS8602 produces a higher normalized stiffness and recovery than SFS5202, likely because of the improvement of braiding pitch and polymeric material.

Synthesis and evaluation of magnetite nanoparticles coated with (acrylamide-vinylpyrrolidone) polymers on the thermostability for application in harsh offshore reservoirs

To avoid the instability and degradation of downhole injection fluids, such as polymers and surfactants, for use in high-temperature (HT) offshore reservoirs, nanofluids with particles modified in different ways have been proposed as a capable thermoresistant, highly active solutions which can be used in many offshore oil and gas exploitation works, especially in enhancing oil recovery. This study presented the process of synthesising two nanocomposite materials for nanofluid preparation. First, magnetite nanoparticles (MNPs(A and B)) were prepared by standard coprecipitation and hydrothermal methods. Then, polymer-coated magnetite nanoparticles (PCM(A) and PCM(B)) were synthesised by directly covering magnetite with oleic acid (OA) to get OA-MNPs, and then simultaneously enveloped with copolymers of acrylamide and the N-vinyl pyrrolidone via polymerisation reaction. The obtained PCMs characteristics were analysed by all required analytical tools. In addition, the thermostability of PCM-based nanofluids as downhole injection agents for HT offshore reservoir applications was investigated by bottle test annealing PCM(A)- and PCM(B)- based nanofluids at the White Tiger (WT) Miocene and Oligocene reservoir temperatures. Based on the obtained data, MNPs have an average particle size of 12 nm and 10 nm for MNPs A and B. A dominant phase of magnetite (Fe3O4) and 10.5% and 11% of the mass of PCM belong to their copolymer coating. The good thermostability of nanofluids annealed for 31 days (at 120 °C for PCM(A)- and 134 °C for PCM(B)-based nanofluids) showed a promised orientation for use as an EOR agent in HT offshore reservoirs recommendation.

Research on Bearing Characteristics of Gravity Anchor in Clay

The applications and studies of gravity anchors in the ocean are becoming more and more extensive. Most of the research, however, has been directed toward the bearing properties of sand. Relatively less attention has been paid to the bearing properties of gravity anchors in clay. Clay is widely distributed on the seabed. The research on the bearing capacity of gravity anchors in clay is of great significance for offshore oil exploitation. Therefore, the gravity anchor was investigated by conducting reduced-scale model tests, and the bearing process of gravity anchors in clay was simulated through a 3D finite element method. Model tests and numerical simulations were used to determine the capacity curve and the V-H failure envelope of gravity anchors in clay. The simulation results and the test results are in good agreement. The failure form of the gravity anchor in clay was revealed by 3D finite element analysis. The effect of cohesion, internal friction angle, and mooring point height on bearing capacity have been studied. The influence of the height of the mooring point on the V-H failure envelope curve was explored by changing the height of the mooring point. The formula of the V-H failure envelope curve suitable for different mooring point heights was obtained.

Dynamic Analysis of Pipeline Lifting Operations for Different Current Velocities and Wave Heights

Pipelines are widely used for transporting oil resources in the context of offshore oil exploitation. The pipeline stress-strength analysis is an important stage in related design and ensuing construction techniques. In this study, assuming representative work environment parameters, pipeline lifting operations are investigated numerically. More specifically, a time-domain coupled dynamic analysis method is used to conduct a hydrodynamic analysis under different current velocities and wave heights. The results show that proper operation requires the lifting points are reasonably set in combination with the length of the pipeline and the position of the lifting device on the construction ship. The impact of waves on the pipeline is limited, however lifting operations under strong wind and waves should be avoided as far as possible.

Study on the automatic optimization design of the cross-sectional layout of an umbilical with layers based on the GA-GLM

Marine umbilical provides the remote control function for offshore oil and gas exploitation, which is usually integrated by different functional components that vary widely in their mechanical properties. Under the action of external load, unreasonable cross-sectional layouts may lead to large cross-sectional deformation and contact pressure between components thus affecting the service life of an umbilical. Therefore, how to design the cross-sectional layout is a very necessary research work in order to improve service life of the umbilical to withstand various loads during operation. At present, the research on the cross-sectional layout of an umbilical is not sufficient, and there is no standardized design method in the design specification. Considering the mechanical and geometrical properties as the quantitative design objectives, the mathematical optimization model of the cross-sectional layout of an umbilical is proposed. Meanwhile, the layering strategy is introduced because of the processing and manufacturing factors.Then, the genetic algorithm (GA) with good global search performance and the generalized Lagrange multiplier (GLM) with fast convergence speed are combined to solve the above model. Finally, taking an umbilical as an example, the optimal cross-sectional layout is obtained and the effectiveness of the algorithm is verified by the numerical simulation. The results show that the optimization method proposed in this paper can quickly obtain the optimal design cross-sectional layout, and supply a specific way for the fast design of an umbilical, which has the certain engineering application value.

Supply and demand balance control of electrical submersible linear motor for offshore oil exploitation

AbstractA supply and demand balance control method for an electrical submersible linear motor utilised in offshore oil exploitation is proposed in this study. The permanent magnet linear motor is replaced by an electrical submersible linear motor based on switched reluctance linear motor. The sensorless control method further enhances the stability of the oil exploitation system. Meanwhile, a supply and demand balance control method is proposed to maintain the fullness of the submersible plunger pump within an ideal range. An established speed function allows the speed of the electrical submersible linear motor to dynamically alter in response to the change in oil deliverability and increasing the system's production. Additionally, maintaining the fullness of the submersible plunger pump within the ideal range helps simplify the model and increase computation accuracy. Finally, the supply and demand balance control method is validated and compared with the intermittent oil exploitation control method by simulations and experiments. Results from the simulations and experiments indicate that the proposed method can increase the production of the offshore oil exploitation system in addition to causing the motor to follow changes in oil deliverability and adjust the speed.

Position Control of Heave Compensation for Offshore Cranes Based on a Particle Swarm Optimized Model Predictive Trajectory Path Controller

The wave compensation system can be very useful in several naval applications. It can greatly reduce the relative irregular motion between the two ships when replenishment operations are performed, or between the ship and the offshore platform, which is caused by the waves. It is widely used in offshore operations, offshore cargo transfer, oil and gas exploitation, deep-sea mining, the hoisting and recovery of submersibles, etc. However, when a crane is used in a ship or moving platform, due to the influence of the hull, the crane load movement is similar to a space ball pendulum, which causes the heave displacement to show significant nonlinear motion characteristics. Moreover, the time delay of the detection mechanism and control error could result in untimely compensation, which deteriorates the performance. Consequently, this paper proposes one advanced prediction compensation method, namely Particle Swarm Optimized Model Predictive Trajectory Path controller (PSO−MPTP), which can improve the heave compensation performance. This method, which is based on Model Predictive Control (MPC), is firstly applied to the position servo system and takes into account the heave prediction and control effects simultaneously. The heave displacement of the crane load could be predicted in multiple steps in advance and used as the input of the position loop of the compensation machine. The achieved simulations show that the proposed controller has better prediction ability, higher control accuracy, and stronger robustness.

Community structure of megabenthos of Perdido Fold Belt (Tamaulipas, Mexico) and its relationship with the oceanographic and sediment parameters including potential pollutants

ABSTRACT Various ecosystems of the Gulf of Mexico (GoM) may be impacted by the present increase in offshore oil exploitation. To identify future changes caused by this activity, we assessed the structure of the megabenthos community in the Perdido Fold Belt (PFB) and its relationships with environmental variables, hydrocarbons, and heavy metals. To achieve this, biological and sediment samples were obtained during the surveys Perdido II (PII) and Perdido III (PIII). 325.75 103 ind km−2 and 582.34 kg AFDW km−2 were collected, distributed in 110 species. Crustaceans and echinoderms comprised more than 70% of the total abundance and biomass. The most abundant species were Astropecten cingulatus Sladen, 1883, Callinectes sapidus Rathbun, 1896, Astropecten duplicatus Gray, 1840, and Penaeus aztecus (Ives, 1891) (12.2 103 ≤ ind Km−2 ≤ 59.4 103). They also had the greatest biomass contribution (16.8 ≤ kg AFDW km−2 ≤ 192.2). BIOENV test showed the influence of depth (Z), salinity, dissolved oxygen (DO), Acenaphthylene (Acy), Fluoranthene (Flu), n-C12, n-C37, and nickel (Ni) on the community structure. Recruitment and trawling also influenced the abundance and biomass values. Despite Z defines the environmental gradient, the hydrocarbon concentration gradient within the shelf areas makes it a good candidate for developing monitoring programmes.