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CIGMAT Report 2013
The addition of 0.5% Xanthan gum reduced the total fluid loss from 180 mL to 24 mL, about an 80% reduction. Also studies are focused on disaster issues caused by hurricanes and other events during drilling operations. The effect of salt contamination on the fluid loss (30 minutes) on xanthan gum modified bentonite drilling mud is shown in Fig. 2. With 0.5% salt (sodium chloride, NaCl) contamination the fluid loss increased by over 30%. Addition of 0.5% surfactant reduced the fluid loss of the contaminated drilling mud by over 40%, a method that can be used to remediate the salt contaminated drilling mud.
Figure 2. Filter loss in salt contaminated and surfactant remediated
xanthan gum modified water based drilling mud
Deepwater axial and lateral sliding pipe-soil interaction model study
Oil producing subsea systems consist of floating platforms connected to subsea wells by a network of pipelines. Deepwater pipelines laid on the seabed, partially penetrate into the soil based on the submerged self-weight of the pipelines and strength of the soil. These pipelines, when transporting oil and gas in deepwater, undergo significant changes in temperature and pressure during service life. In addition some of the deepwater oil pipelines are on very soft sea bed and are susceptible to axial and lateral movement (or walking) of pipelines due to cyclic thermal changes and lateral buckling due to thermal expansion under operating conditions. Correctly predicting axial ‘walking’ and controlling lateral buckling is extremely sensitive to the selection of pipe-soil interaction parameters during the safe design of the network of pipelines. However the soil resistance to various types of pipe movement is a significant uncertainty and hence the current practice relies on empirical expression for pipe-soil resistance. Although there are several numerical approaches proposed to model the pipe-soil interaction there is very limited experimental studies and quantification of various important parameters for designing and maintaining network of pipelines.