Abstract: The causes of failed wildcat wells in the eastern Pearl River Mouth Basin were analyzed comprehensively to clarify the factors influencing the exploration results and guide the following exploration in this area. It is shown that the factors leading to the failure of wildcat wells are ranked as migration-accumulation matching condition, trap condition, reservoir condition, source rock condition, caprock condition and preservation condition according to their priorities. Then, the failure factors were classifed and analyzed from three aspects of water depth, oil bearing layer and trap type. It is indicated that the failure factors of different types of wildcat wells are similar in some aspects and different in other aspects. As for their similarities, migration-accumulation matching condition is the top one factor for the failure of wildcat wells, mainly referring to migration direction and migration pathway, trap condition takes the second place, including the uncertainty of structural trap form and the sealing of fault, and the failure caused by caprock and preservation conditions is less. The differences are as follows. The failure caused by reservoir condition is obvious in deepwater area, deep layer, buried hill, lithologic trap, stratigraphic trap and combination trap, while source rock and caprock occupy a certain proportion for the failure of wildcat wells in shallow water area. Besides, the failure caused by poor fault sealing is relatively common in fault control traps, and the confrmation of lithologic trap and structural-lithologic trap is faced with larger risks. In the following exploration, it is necessary to strengthen the researches on migration-accumulation matching condition and trap condition. And for different types of targets, it is also necessary to focus on the prominent risk factors and carry out the specifc study to reduce the risks.

Key words: the eastern Pearl River Mouth Basin, wildcat well, causes of the failure, migration-accumulation match, trap condition, reservoir condition