临盘油田夏38井区辉绿岩热效应对成烃作用的影响  

Influences of thermal effect of diabase intrusion on hydrocarbon generation in Xia 38 wellblockLinpan oilfield

作　　者：曹学伟[1] 胡文瑄[1] 金之钧[2] 朱东亚[1] 

机构地区：[1]南京大学地球科学系,江苏南京210093 [2]中国石化石油勘探开发研究院,北京100083

出　　处：《石油与天然气地质》2005年第3期317-322,共6页Oil & Gas Geology

基　　金：国家"973"重点基础研究发展规划项目(G1999043309)

摘　　要：济阳坳陷临盘油田夏38井区沙河街组三段辉绿岩侵入体对上、下烃源岩的显微有机质和镜质体反射率的影响非常显著,影响的范围大致与岩床厚度相当。在靠近岩床10 m 范围内,镜质体反射率(R_o)值比正常地温场条件下升高1至数倍,最高可达3.44%。远离岩床烃源岩受热影响强度逐渐降低,直至50m 以外趋于正常地温值。由于扩散、对流条件等存在差异,岩体对上覆岩层影响范围大,但幅度小;对下伏岩层影响范围小,但幅度大。在岩浆热能影响下,快速形成的烃类在碳数分布上具有“头大尾巴长”的特点,即以中-轻烃为主,重烃含量明显偏少。与正常地温场缓慢生成烃类的轻、重烃平衡、对称的分布模式明显不同。理论估算,岩浆带来的热量足以使侵入体附近5倍于岩床体积的烃源岩升高200℃,但由于孔隙流体的对流散热,温度升高的幅度比理论计算值要小。Diabase intrusions in the 3rd member of Shahejie Fm in Xia38 wellblock of Linpan oilfield,Jiyang depres- sion,have very remarkable influences on maceral and vitrinite retlectance(R_0)of source rocks above and below the intrusion,and the range of the effect is approximately equivalent to the thickness of the sill.The R_0 value within 10m around the sill is 1 to several times of that at normal geothermal field condition,and can even be as high as 3.44%. The intensity of thermal effect's impacts on the source rocks decrease progressively away from the sill,and tend to be normal geotemperature over 50m away form the sill.As a result of different diffusion and convection conditions,influ- ences of the sill on overlying rocks are large in scope but low in intensity;while that on underlain rocks are small in scope but high in intensity.Hydrocarbons that have been generated rapidly under the influenee of magmatie thermal energy are mainly of medium-light hydrocarbons,while heaW hydrocarbons are obviously less.Such hydrocarbon dis- tribution pattern is clearly different from that generated slowly in normal geothermal fields,whieh shows symmetrical distribution with balanced light and heavy hydrocarbons.Theoretical calculation shows that the thermal energy from magma might sufficiently cause the temperauure of source rocks nearby with a volume of 5 times that of the intrusion to rise 200℃.The real increase of temperature,however,might be smaller than the theoretieal calculation results.

关 键 词：热效应 镜质体反射率(Ro) 可溶烃特点 辉绿岩床 烃源岩 临盘油田 

分 类 号：TE112.1[石油与天然气工程—油气勘探]