Hi Brijesh,
Please see below my thoughts on your queries:
1>> The key products of Vinati are IB, IBB and ATBS. You are correct there could be disruption in terms of discontinuity of use of some products in some applications or fear of substitute. The application of these chemicals are very broad ranging from water treatment, adhesives, personal care, gelatin substitutes, epoxy resin, coatings, construction chemicals, mining chemicals etc. Hence, I believe the threat of disruption is also diversified and suddenly there will be no big impact on usage.
Read: Pg. 16 and 17 of annual report for applications >> http://www.nseindia.com/annual_reports/AR_6524_VINATIORGA_2014_2015_16072015160500.zip
2>> The application of ATBS in oil industry is to act as sealant to prevent leakage during high pressure oil while drilling and doing maintenance. As per my understanding this forms only part of ATBS application and guess if there would have been impact of falling oil prices this would have been evident till now but on contarary the market share has increased to 45%+ during last year. Also, Vinati Saraf has spoke about ATBS application and impact in one of the videos you can find it below:
http://www.moneycontrol.com/video/results-boardroom/confidentmaintaining-margins-at-20-vinati-organics_1152103.html
OR
http://www.moneycontrol.com/video/results-boardroom/vinati-organics-pegs-sales-at-rs-1000crnext-4-5-years_545577.html