Effectiveness and limitations of CSEM survey for oil and gas exploration

Abstract

Marine CSEM survey over 9 anticlinal structures was conducted in deep water exploration blocks in Malaysia. Later 4 of the 9 structures were drilled and found 3 “true negative” and 1 “false negative” in terms of CSEM results. In the “false negative” case, CSEM failed to predict the well result where a certain amount of oil and gas was discovered by a well despite lack of CSEM anomaly. Since the inverted resistivity profiles are coincide with well logging data at shallow part, validity of the CSEM theory and technique is undoubtable. Based on our experiences and case studies in literature, Marine CSEM survey is deemed to be effective and useful when applied to shallow target, thick net reservoir, wide hydrocarbon accumulation area, and deep-water environment.