Esso Australia Pty Ltd (Esso), in a joint venture with BHP Petroleum Pty Ltd, operates 23 oil and gas production platforms and subsea facilities off the Victorian coast near Gippsland, Australia. The underlying reservoirs have multi-darcy sands and a strong aquifer water drive, so in addition to oil and gas, the extraction activities result in substantial amounts of produced formation water (PFW). Following on-platform treatment, PFW containing a variety of hydrocarbons, ions and inorganics, such as calcium, ammonia, sulfate and trace metals, is discharged into the receiving environment. This paper reports on a study undertaken to investigate the potential effects of PFW discharges from two platforms (Tuna (TNA) and West Kingfish (WKF)) on the receiving environment. Four complementary sampling approaches were used to address the objectives of the study: (1) measure and estimate the dilution of Rhodamine FWT dye solution in the receiving environment following injection into the PFW discharge line, (2) collect and analyse undiluted PFW samples before discharge, (3) collect and analyse marine water samples from within the discharge plume and (4) collect and analyse sediment and benthic infauna samples at various distances away from platforms and at reference locations. Results indicate the rate of PFW dilution within the receiving environment is more rapid than predicted by existing numerical models and that the concentration of all analytes present in PFW were below Australian and New Zealand Environment Conservation Council (ANZECC) 2000 guideline trigger values for 80% protection; moreover, with one exception, analytes were not detected above background levels more than 59 m from the platform. With the exception of a few samples containing metals, specifically arsenic, copper, lead, zinc and nickel, concentrations of analytes in the majority of sediment samples collected were below the ANZECC 2000 and revised 2013 sediment quality guidelines. A diverse range of benthic infauna were sampled, with the abundance of a limited number of taxa influenced by distance from individual platforms. No substantial differences in abundances of benthic infauna were detected at distances greater than 1.3 km from TNA and 1.0 km from WKF, compared with reference locations. These results indicate that PFW discharges from TNA and WKF likely represent a low risk to the receiving environment.
T he drilling of large quantities of repetitive holes during the manufacture of large aerospace components is often considered a key limiting factor with regards to production efficiency. Whilst the desire within aerospace is to use relatively cheap six axis robot arms with drilling end effector units, their poor accuracy remains an obstacle. Robot calibration presents a way of improving robot accuracy such that aerospace drilling tolerances can be met, without permanently committing metrology equipment to an automation cell during production. Extensive research has been conducted into robot calibration by correcting the kinematic model, known as parametric calibration. This method is highly complex, and calibrates the robot across the entire working volume. This is often not required in industrial drilling applications, as drilling routines are often contained within a smaller volume of the robot reach. In this paper, a nonparametric method of robot calibration is proposed. This method involves calibrating within regions of the working volume where the robot pose is similar, and thus the effects of geometric errors in the kinematic model are roughly constant. By establishing the average positional error for each region, the accuracy can be locally improved by compensation through definition of the tool centre point. The proposed method can be completed without the use of kinematic models or complex mathematics, making it more suitable to industrial users. From experimental trials, a significant improvement in the positional accuracy of holes drilled using a standard six axis robot is reported, from 2 mm to 0.1 mm, well within the requirements of the majority of aerospace applications.
This work proposes a novel solution for detecting and tracing spatially varying edges of large manufacturing workpieces, using a consumer grade RGB depth camera, with only a partial view of the workpiece and without prior knowledge. The proposed system can visually detect and trace various edges, with a wide array of degrees, to an accuracy of 15 mm or less, without the need for any previous information, setup or planning. A combination of physical experiments on the setup and more complex simulated experiments were conducted. The effectiveness of the system is demonstrated via simulated and physical experiments carried out on both acute and obtuse edges, as well as typical aerospace structures, made from a variety of materials, with dimensions ranging from 400 mm to 600 mm. Simulated results show that, with artificial noise added, the solution presented can detect aerospace structures to an accuracy of 40 mm or less, depending on the amount of noise present, while physical aerospace inspired structures can be traced with a consistent accuracy of 5 mm regardless of the cardinal direction. Compared to current industrial solutions, the lack of required planning and robustness of edge detection means it should be able to complete tasks more quickly and easily than the current standard, with a lower financial and computational cost than the current techniques being used within.
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