In trading on Monday, shares of Schlumberger entered into oversold territory, changing hands as low as $48.61 per share. We define oversold territory using the Relative Strength Index, or RSI, which is a technical analysis indicator used to measure momentum on a scale of zero to 100. A stock is considered to be oversold if the RSI reading falls below 30.Start slideshow: 10 Oversold Energy Stocks »In the case of Schlumberger, the RSI reading has hit 28.4 — by comparison, the universe of energy stocks covered ...