Liquefied petroleum gas and light hydrocarbons. Determination of density or relative density. Pressure hydrometer method

It is very important to study the pristine stress field in Civil, Mining, Petroleum engineering as well as in Geology, Geophysics, and Seismology. There are various methods of determination of in-situ stress in rock mass. However, hydraulic fracturing techniques is the most convenient method to determine and interpret the test results. Based on an hydraulic fracturing stress measurement campaign at an underground liquefied petroleum gas storage project which locates in ZhuHai, China, this paper briefly describes the various uses of stress measurement, details of hydraulic fracturing test system, test procedure adopted and the concept of hydraulic fracturing in arriving at the in-situ stresses of the rock mass.

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Coke. Determination of true relative density, apparent relative density and porosity

10.3403/30423449 ◽

2021 ◽

Keyword(s):

Relative Density

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A baited underwater video system for the determination of relative density of carnivorous reef fish

Marine and Freshwater Research ◽

10.1071/mf00010 ◽

2000 ◽

Vol 51 (8) ◽

pp. 755 ◽

Cited By ~ 175

Author(s):

Trevor J. Willis ◽

Russell C. Babcock

Keyword(s):

Relative Density ◽

Size Structure ◽

Marine Reserve ◽

Reef Fishes ◽

Underwater Video ◽

Underwater Visual Census ◽

Video Footage ◽

Survey Techniques ◽

Scuba Divers

Estimates of the relative density of fishes form the basis of many marine ecological studies as well as the assessment of effects of fishing or pollution. Plasticity in the behavioural response of large reef fishes to SCUBA divers means that commonly used underwater visual census (UVC) techniques do not always provide reliable estimates of relative density. The paper describes the system configuration, deployment methods, testing and use of a remotely deployed baited underwater video (BUV) system for the survey of carnivorous reef fishes (snapper, Pagrus auratus and blue cod,Parapercis colias) in marine reserves of northern New Zealand. Concurrent UVC and BUV surveys inside and outside a marine reserve showed that, whereas UVC detected few snapper in either area (resulting in little confidence in statistically significant results), BUV demonstrated significant differences in relative density. Conversely, blue cod were found to occur at significantly higher densities within the reserve by UVC, but not by BUV. The provision of accurate estimates of fish size (<20 mm error) from video footage also illustrated differences in size structure between protected and fished populations. The data suggest that a combination of survey techniques is likely to be necessary where multispecies assemblages are being assessed.

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