Abstract:

Hydrocarbon fingerprint characteristics of natural gas can be effectively used to analyze connectivity between gas layers in J_3p1 gas pool in Xinchang gas field.In wellblocks or intervals favorable for gas accumulation,certain hydrocarbon fingerprint parameters that are related to gas accumulation and preservation conditions show evident regularity,such as C_3-4/C_5-6,alkane C_5-6/C_7-8 and hexane/cyclehoxane show obvious increasing trend,while normal alkane/isoalkane,cyclopentane/cyclohexane and isomeric mono-substitution/isomeric poly-substitution show relatively decreasing trend.All the hydrocarbon fingerprint parameters of gas layers in J_3p1 gas pool in Xinchang gas field show prominent lateral variation and connectivity between gas layers is poor,indicating the characteristics of structural-lithologic gas pool.The clear regularity of hydrocarbon fingerprint parameters from shallow to deep layers reflects the chromatographic effect and the component separating process during gas migration and accumulation,i.e.gas pools have mainly been formed through vertical migration of hydrocarbons generated from the deep source rocks.All these indicate that conditions of hydrocarbon accumulation and preservation would become better and better to the deep layers,and there will be the possibility of discovering gas pools at depth.

Key words: natural gas, hydrocarbon fingerprint, gas pool, geochemistry, description