原油裂解气的地球化学特征、形成条件与资源评价——以塔里木盆地台盆区为例

根据模拟实验所揭示的原油裂解气和干酪根裂解气化学组成地球化学特征,结合塔里木盆地实际气藏天然气化学组成的剖析,证明塔里木盆地台盆区确实存在两种C_2/C_3与C_1/C_2、C_2/C_3与C_1/C_3、C_2/C_3与100×C_1/(C_1-C_5)分布关系不同的天然气,认为C_2/C_3与C_1/C_2、C_2/C_3与C_1/C_3、C_2/C_3与100×C_1/(C_1-C_5)关系图版可作为区分原油裂解气和干酪根裂解气的有效图版;原油裂解气藏所在地区的石油地质条件的分析表明,原油裂解气的分布大多与深大断裂或断距较大的断层有关,且古油藏埋深较大;利用正演法和反演估算法对原油裂解气资源量进行计算,得出C_2/C_3与C_1/C_2、C_2/C_3与C_1/C_3、C_2/C_3与100×C_1/(C_1-C_5)可以用来判定原油裂解气和干酪根裂解气在天然气中所占的比例,并以此确定了台盆区主要气藏天然气混合比例.

Geochemical Characteristics and Forming Conditions and Resource Evaluation of Crude Oil Cracking Gas-By Taking Platform Area of Tarim Basin for Example

Based on geochemical characteristics of oil cracking gas and kerogen pyrolysis gas revealed by simulation experiments, and in combination with the analysis of chemical composition of natural gas in actual gas reservoirs in Tarim Basin. It is proved that there existed two kinds of natural gases with different relationships between C_2 /C_3 and C_1/C_2 , C_2/C_3 and C_1/C_3、C_2/C_3 and 100 × C_1 /(C_1 -C_5 ) , and it is further proposed that the distribution of the relationships between C_2/C_3 and C_1 /C_2 ,C_2/C_3 and C_1 /C_3、C_2/C_3 and 100 ×C_1 /(C_1-C_5 )can be used to distinguish effectively the crude oil cracking gas and kerogen pyrolysis gas; the analysis of petroleum geology of crude oil cracking gas reservoir shows that the distribution of crude oil cracking gas is mostly related with deep seated faults or faults with lager fault throw, and the depth of ancient reservoir is greater; crude oil gas resources are calculated by using forward and inversion methods, the ratios of C_2/C_3 and C_1 /C_2 ,C_2 /C_1 and C_1/C_3、C_2/C_3 and 100 × C_ 1/(C_1-C_5 )are considered as a helpful means to identify the proportion of crude oil cracking gas and kerogen pyrolysis gas for determining the mixing ratio of natural gas in the main gas reservoirs in the platform area.