Due to the increasing energy demands, the offshore energy business has boomed in recent decades. Sub-sea pipeline and power transmission cable installations are commonly applied worldwide. Any potential breakages can cause equipment damage and also damage the environment. The majority of the offshore pipeline inspections are currently committed using Towed or Remotely Operated Vehicle (ROV) systems. It is well-known that the ROVs are very time-consuming and expensive to operate, with respect to the fact that they require a relatively large support ship to accommodate the equipment as well as very skilled pilot and crews.

Acoustic and optical sensing modalities represent two of the primary sensing methods within underwater environments, and both have been researched extensively in previous works. Acoustic sensing is the premier method due to its high transmissivity in water and its relative immunity to environmental factors such as water clarity. Optical sensing is, however, valuable for many operational and inspection tasks and is readily understood by human operators. In this work, we quantify and compare the operational characteristics and environmental effects of turbidity and illumination on two commercial-off-the-shelf sensors and an additional augmented optical method, including: a high-frequency, forward-looking inspection sonar, a stereo camera with built-in stereo depth estimation, and color imaging, where a laser has been added for distance triangulation. The sensors have been compared in a controlled underwater environment with known target objects to ascertain quantitative operation performance, and it is shown that optical stereo depth estimation and laser triangulation operate satisfactorily at low and medium turbidites up to a distance of approximately one meter, with an error below 2 cm and 12 cm, respectively; acoustic measurements are almost completely unaffected up to two meters under high turbidity, with an error below 5 cm. Moreover, the stereo vision algorithm is slightly more robust than laser-line triangulation across turbidity and lighting conditions. Future work will concern the improvement of the stereo reconstruction and laser triangulation by algorithm enhancement and the fusion of the two sensing modalities.

In the oil and gas industry, the gas-lift assist approach is often used in the production wells when the reservoir pressure is insufficient to ensure cost-effective production. However the side-effect of this approach is the often occurrence of regular/irregular large oscillations of the production flow and pressures in the production well system, which is referred to as the slugging flow problem. This instability is mainly due to the casing-heading mechanism. This work investigates the possibility to use a feedback control for stabilizing the production operation without sacrificing the production capability. A lab-sized production well system is constructed in an economic manner. Afterwards, a simple nonlinear model is derived according to physical principles and then verified with the experimental facility. A observer-based state feedback control is designed to handle the potential slugging problem. The developed controller manipulates the openness degree of the production choke based on feedback a number of pressure measurements. The current simulation results showed satisfactory control performances by stabilizing the system operation at some relatively large production rate which is originally open-loop unstable.

Tremendous amount of produced water are discharged into the sea from offshore oil & gas installations. Along with every barrel of oil three barrels of water are produced and this is only worsen as the fields mature. Enhanced oil recovery (EOR) is employed to increase production, as a part of EOR the Water Flooding Technology (WFT) is employed. The quality requirements for WFT and the increasing environmental concerns for produced water discharge lead to increased interest in zero-pollutant discharge. Traditional Produced Water Treatment (PWT) technologies(such as hydrocyclones) are already struggling to their fundamental limit, therefore the membrane filtration technology turns to be a potential candidate for zero-pollutant discharge. Membrane filtration technology suffers from the notorious fouling problem, where many methods for fouling prevention and removal are explored, the general idea is to guarantee that a relatively high permeability can be kept during filtration. Another crucial issue using membrane filtration technology is its huge energy consumption, for which there is little research has been done so far to systematically investigate and optimize the filtration system's energy efficiency, some smart filtration technology could contribute to handle this issue.