The analysis of a large number of oil samples demonstrates that the Mesozoic-Cenozoic gas condensates and high-gravity oil in Kuqa Depression feature a high wax content.The study discusses the origin and controlling factors of gas condensates with high wax content and high gravity oil in Kuqa Depression based on previous research and available data.The results show that some exinite and sapropelinite of the organic macerals in source rocks are turned into oil with high wax content

whilst vitrinite of the organic macerals produces gas condensates and high-gravity oil.These organic macerals determine the production of gas condensates with a high wax content and high-gravity oil in Kuqa Depression.The wax content in crudes is mainly controlled by three factors: oil maturity

hydrocarbon reservoir type

gas washing and oil migration.Among them

the oil maturity is predominant.The oil in Kuqa Depression is generated by thermal evolution of source rocks during its mature stage

with oil maturity R

o

ranging between 0.8%-1.05%

while the crudes as a whole are characterized by a high wax content

and the wax content in crudes decreases with increasing oil maturity.Besides

the hydrocarbon reservoir type plays a secondary role.The wax content of crudes is less than 5% in dry gas reservoirs

ranges between 5%-10% in condensate gas reservoirs with low gas condensates

while is more than 10% in condensate gas reservoirs with high content of gas condensates and oil reservoirs;the wax content of crudes increases with the decrease of lo-garithm of producing gas/oil ratio of hydrocarbon reservoirs.In addition

the effect of gas washing and oil migration ranks last.Under the same oil source conditions

the higher degree of gas washing the crudes undergo

the lower the wax content of crudes will be;meanwhile the farther the crudes migrate

the lower the wax content of crudes will be.