Offshore Drilling Systems Research Articles

Hybrid physics-based and machine learning model with interpretability and uncertainty for real-time estimation of unmeasurable parts

Physics-based models are used to estimate the behavior of dynamic systems. However, these models contain uncertainties, i.e., “parameter uncertainty” and “structural uncertainty,” which cause the gap between real phenomena and physics-based models (reality gap). Kaneko et al., (2022) proposed a hybrid physics-based and machine learning model for the real-time estimation of unmeasurable parts and demonstrated the high performance for the “parameter uncertainty.” This study verifies the hybrid model performance for the “structural uncertainty.” Additionally, two new concepts are discussed, interpretability and uncertainty, and implemented in the hybrid model.The hybrid model performance for the structural uncertainty is examined by numerical experiments and application to measured data using a deep-water offshore drilling system as an application case study. The results show that the hybrid model gives robust estimation for the structural uncertainty. Additionally, the hybrid model accuracy increases as the physics-based model accuracy used for training increases. Furthermore, several seconds of future data could improve the model performance for the transient response. Finally, we show that two new outputs could effectively explain the reality gap; the model outputs the estimation of the uncertain parameter to give interpretability within the parameter uncertainty and the structural uncertainty metric outside the parameter uncertainty.

Hybrid model of a physics-based model and machine learning for real-time estimation of unmeasurable parts: Mapping from measurable to unmeasurable variables

In some dynamic systems, such as offshore drilling, it is important to estimate the behaviour of unmeasurable parts in real-time, using measurable data. This article proposes a novel hybrid model of a physics-based model and machine learning (proposed model), which maps measurable variables to unmeasurable variables. The effectiveness of the proposed model was verified by comparing it with the conventional physics-based model and grey-box model, using an offshore drilling system as a case study application. As a result, it was confirmed that the proposed model could relax the required conditions of the measured data’s sampling period and time length when compared to the conventional model by directly inputting the measurable data. Additionally, we confirmed that the proposed model solves the time cost for parameter adjustment in the grey-box model and is superior in real-time performance. The proposed model was also shown to be robust against measurement errors. Thus, it is demonstrated that the proposed model has a high performance when the real phenomena can be represented within the physics-based model’s uncertainty of the initial states and parameters. The proposed model is expected to be suitable for various dynamic systems in addition to offshore drilling systems.

Pressure Loss Optimization to Reduce Pipeline Clogging in Bulk Transfer System of Offshore Drilling Rig

In offshore drilling systems, the equipment localization rate is less than 20%, and the monopoly of a few foreign conglomerates over the equipment is intensifying. To break this monopoly, active technology development and market entry strategies are required. In a drillship or a floating production, storage, and offloading unit, the distance from the tank top to the upper deck is approximately 30–40 m. Therefore, the pressure loss problem inside the vertical pipe from the tank to the deck should be considered. To transport the bulk at the target transport rate without clogging, the pressure loss inside the vertical pipe should be optimized. Moreover, the operating pressure, air volume, and transport rate accuracy determine the system and operating costs. Hence, system optimization is necessary. In this study, pressure loss modeling and simulation of the bulk transfer system are performed to prevent frequent pipeline clogging. The proposed simulation model is verified using real test data. The bulk transfer system is verified through a simulation, indicating an error rate of 4.27%. In addition, the number of air boosters required to minimize the pipeline’s pressure loss and the optimal distance between the boosters are obtained using a genetic algorithm. With the optimized air booster, pressure loss for approximately 0.54 bar was compensated. The improved bulk transfer system is expected to reduce uncertainty and minimize maintenance and repair costs during operation. Moreover, it can contribute to high-value fields such as construction, commissioning, installation, maintenance, and equipment localization improvement.

FRAM AHP approach to analyse offshore oil well drilling and construction focused on human factors

Since the beginning of the well-drilling activities of oil and gas industry, in the 19th century, these activities have presented specific risks that, over the course of their evolution to the present day, have greatly increased their potential to cause harm to people, the environment, and corporate sustainability. Stimulated by the world’s energy needs, especially in developed and growing countries, the technology used by the O&G industry has evolved significantly, not only to increase production and profit levels, but also to reduce the risks of these activities, using reliable automation and other barriers to worker protection. However, despite all this investment, accidents such as the Deepwater Horizon, in 2010, and Odebrecht NS-32, in 2017, shown that there are still gaps in this process of evolution of protection systems, especially those used in highly complex systems such as offshore oil rigs. In addition, inevitably, the technological contribution implemented in offshore drilling systems increases their complexity and, consequently, also increases the complexity of the relationship between workers, systems, machines, and environment, definitively characterizing oil rigs as complex socio-technical systems. Keeping that in mind, a FRAM model was developed to understand the levels of complexity and show the relevant human factors that are critical for the safe operations of these workplaces, considering the natural and variability that emerges from these labour scenarios. Some functions of the FRAM model built presented significant variability, as function “Perform drilling operations”, where the most significant variabilities were observed in its 10 outputs, causing a large resonance within the model, once their couplings, mostly in their control aspects, can vary in terms of time and precision.

Safety barriers analysis of offshore drilling system by employing Fuzzy Event Tree Analysis

In technical systems like oil and gas drilling systems, an accident sequence starts with an Initiating Event (IE) and evolves over time through the interaction of barriers in terms of success or failure. As it has been dramatically demonstrated in a variety of cases, offshore oil rigs activities have severe consequences to people, asset, environment and reputation.A survey carried out on a leakage event in production phase. The barriers of the above IE are assessed by Event Tree Analysis (ETA) which evaluates the sequence of events in a potential accident scenario following the occurrence of an IE. In this research to calculate Failure Probability (FP) of barriers new approach is proposed. In this methodology, Reliability Block Diagram (RBD) and Fault Tree Analysis (FTA) are employed to quantify barriers FP. RBD is useful tool to quantify FP of barriers with logic diagram. FP of barriers with logic diagram is obtained by FTA. However it is often difficult to estimate precisely the FP of the components due to insufficient data. It has been reported that availability of the FP data pertaining to local conditions is surprisingly limited. In this study to overcome this problem using of expert judgment and then fuzzy logic is employed. Therefore, Fuzzy FTA (FFTA) is used to reduce uncertainty of expert judgment.

Design and Research of Offshore Drilling Platform Electric Power System

In order to design a reasonable safe power control system and realize the automated management of offshore drilling system, this paper analyzes the electric system features and grid configuration of drilling platform; power station design and short circuit calculation; electrical power system electroplax selection. This system adopts oceanographic engineering software EDSA for construction and parameter input and conducts short-circuit calculation for modeling and simulation. The electric system design and short-circuit calculation can be examined by simulation result and real platform.

ABSTRACT: Seafloor Drilling of the Hydrate Economic Zone for Exploration and Production of Methane

The economic production of natural gas from oceanic hydrate deposits will not occur using offshore drilling systems. The high cost of semi-submersible or tethered, deep-water, offshore drilling equipment is economically justified by high production of dry gas over a long time. By definition, hydrated formations will produce wet gas at low pressure and low production rates. Fortunately hydrates are located relatively close to the seafloor when compared to conventional gas reservoirs. Large numbers of low-cost wells could produce enough gas to recover costs. A workboat-based drilling system that includes an integrated gas production capability is described.

Operating requirements for and historical operations of Arctic offshore drilling systems in the United States

The MMS regulatory program has been designed to ensure safe, pollution-free operations and adequate structural integrity of all drilling units proposed for use under the dynamic environmental conditions of the Arctic OCS. The COCP's have been developed and implemented to ensure the continued safety of operations under prevailing weather and ice conditions. The level of forecasting, ice monitoring, communications, ice management, and drilling-unit performance monitoring depend on the type and location of the proposed operations. These efforts are analyzed by the MMS on a case-by-case basis, taking into consideration all relevant information available about the drilling unit and the anticipated environmental conditions. All drilling units used for exploration drilling in the U.S. Arctic have operated safely and effectively under dynamic and challenging conditions. The expanding information base, the experience gained, the emphasis on safety, and a conservative approach to conducting operations have all contributed to the conduct of safe pollution-free operations in the harsh and challenging frontier of the U.S. Arctic OCS waters.

Icebreaking Drillship for Offshore Exploratory Drilling in the Arctic

An offshore drilling system designed expressly for the unique environment of the Arctic must take into account many parameters. This paper discusses design considerations for a drillship intended for extended offshore operation in the Arctic areas. Discussion of environmental protection and safety features for icebreakers, shipping rules, and icebreaking capability are included. Introduction About 3 years ago it became apparent that the offshore oil potential in the Beaufort Sea and Canadian Arctic Islands areas was sufficient to give serious consideration to practically and economically providing a system capable of performing the needed exploratory drilling service. The practical approach was to use proven drilling techniques, systems, and equipment, proven drilling techniques, systems, and equipment, but to apply them to an environment not previously considered in their design, using imagination to accept opposing precepts to conceive a workable compromise. Economics dictate that the results must be reasonably capable of profitable application. A preference for ship-shaped units for exploratory drilling and the existing technology for breaking navigable ice channels with ships afforded a marriageable pair of disciplines. The only total unknown was how pair of disciplines. The only total unknown was how to maintain a drilling station in a slowly moving ice sheet. Design Considerations Combining a drillship with an icebreaker provided the basis for the design considerations (Fig. 1). Throughout the design of the vessel, safety was the over-riding criterion - safety not only for the personnel, vessel, and equipment, but also safety personnel, vessel, and equipment, but also safety in terms of environmental protection. The design evolved around considerations of environmental parameters such as climatic conditions and their parameters such as climatic conditions and their impact; crew, equipment, and vessel safety; regulatory parameters; and icebreaking and operational requirements. Environmental Parameters Experience with ship-shaped drilling vessels was a starting point for the design. This experience was adapted to the hostile climate of the Arctic. Where interfacing problems between the drillship and the icebreaker were encountered, the solution was normally an adaptation of drilling equipment or systems to the environment. The winters of the Beaufort Sea and Canadian Arctic Islands are long and severe. Although temperatures do not fall as far below zero as they do in the southern continental belt of the Arctic, the cold is persistent. The chill factor, coupled with the strong prevailing winds, makes this a very hostile region during the winter months. The long period of total darkness further complicates operations period of total darkness further complicates operations in the Arctic during this season. The summers in this area are cool and short. Cloudiness is prevalent along the coast because of the open water and abundant moisture, The clouds are always low and their formation lasts longer where open water and ice coexist. Snow occurs during every month of the year in the Beaufort Sea region. On the other hand, rain has never been recorded from October through May at most Arctic weather stations. During the summer months (June through September), rain accounts for more than 75 percent of the precipitation. The water equivalent of the mean annual precipitation is about 8 in., divided almost equally between rain and snow. JPT P. 433

Current Trends in Offshore Drilling Rigs

The increasing global energy requirements have caused a large demand for mobile offshore drilling vessels. More sophisticated, cost-effective vessels are necessary to operate in the often severe wind, wave, ice, current, and deep-water environments. Through the efficient use of data processing, aerospace structural and advanced hydrodynamic techniques and instrumentation, the state of the art of drilling vessel design and operation has progressed considerably in recent years. Increasing sophistication will be necessary to develop future generations of offshore drilling systems.