Forecast of Crude oil price for next 2-4 years: professional technical analysis

Crude oil broke important levels recently. It is in a strong down trend which is not easy to reverse. Lets have a look at the prices for the past 25 years in the chart. There is good support at $50 (See S1 marked in chart) meaning that it can stop falling at that level. If it breaks $50 level and falls further, it will find very strong support first around 43$ (S2 in chart ) then at $40. The reversal of downtrend into an uptrend will probably take 2 to 4 years as evident from the past behaviour of crude oil prices in 1998-2000 and 2008-2010 trend changes. We can assume a stop in the downtrend when price goes above $70. But before that it has to cross the $60 level (marked R1 in chart) which will not be easy. When the trend will change, crude oil price will cross above 80$ level. Before it crosses $80, it may be assumed to remain in sideways movement meaning that there will not be much appreciation.

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Questions and critical analysis is welcome.