As prices of energy resources such as oil and gas started to rise steadily in 2000, energy security has been one of the most important topics in the world. To secure more energy, most of countries which are highly dependent on imported energy resources try to occupy oversea oil or gas reserves, thereby intensifying competition for energy resources around world. Under this circumstance, we focus on independent E&P companies since they are relatively small size companies which are suitable for M&A. We analyze investment option values for these E&P companies using a real option model for depletable resources. Based on analytical model, empirical study is provided to examine rationality of investment for energy companies. The result shows sufficient profitability for independent E&P companies in both oil and gas projects in the North America during 2004 to 2008. In Particular, oil projects were more feasible than gas project due to lower price of gas and high volatility of gas price at that time.