Appraisal is is one of the five stages of an oil field over its span of life. Worldwide oil and gas companies are spending billions of dollars in collecting data/ information after discovery of oil to maximise the value of projects. However, most often it has been obesreved that either discovery is under or over appraised due to improper definition of required data / information. What are the best practices to optimize the appraisal strategy and data collection?? What are the critical components and their roles in appraisal ??