Method for assessing the acute toxicity of drilling fluid rapidly by utilizing marine microalgae

Abstract

The invention relates to biotoxicity assessment of drilling fluid, in particular to a method for assessing the acute toxicity of the drilling fluid rapidly by utilizing marine microalgae. The method is as follows: carrying out mixed culture on marine microalgae fluid in a steady growth phase and stock fluid of the drilling fluid for 3-8 hours; sampling, and measuring fluorescence emission spectrum to obtain chlorophyll fluorescence intensity of the algae at the position of 678-685nm; taking the fluorescence intensity of the microalgae without the added stock fluid as contrast, and calculating relative mortality rate of the microalgae; and according to the relative mortality rate of the microalgae, utilizing Curveexpert or Microsoft Excel 2003 software to draw a relation curve between the mortality rate of the microalgae and the concentration of the drilling fluid, and determining whether the drilling fluid is toxic or non-toxic according to the national standard on the basis of 7-8h EC50 value. The assessment result to the toxicity of the water-based drilling fluid by utilizing the microalgae method established by the biotoxicity assessment of the drilling fluid is consistent to that of 96h LC50 of artemia, the time is shortened by 88 hours compared with the conventional 96-hour biotoxicity test time, and the field usage can be achieved.

Description

technical field [0001] The invention relates to biological toxicity evaluation of drilling fluid, in particular to a method for quickly evaluating the acute toxicity of drilling fluid by using marine microalgae. Background technique [0002] Drilling fluid is an extremely complex multiphase stable colloidal suspension composed of water and various chemical treatment agents, and its biological toxicity mainly comes from the components of drilling fluid. The research on biological toxicity evaluation of drilling fluids began in the 1960s, and a variety of evaluation methods including 96h acute toxicity and chronic toxicity have been developed, and various test organisms are used, including mysis, luminescent bacteria, Marine microalgae (such as Skeletonema costatum, which is the Skeletalum costatum selected in this work), copepods, fleas and fish, bivalve molluscs, and amphipods. Countries such as the United States mainly test the toxicity of drilling fluids, while organizati...

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Problems solved by technology

[0010] In a word, the usual 96h toxicity test is difficult to be applied in the field. The luminescent bacteria method and the luminescent algae method can be applied in the field because of their simplicity and rapidity. However, the former requires the drilling fluid to be colorless or nearly colorless, and the latter requires the drilling fluid to be pH is 7.5-8.0, otherwise the test result will be inaccurate

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