梨树断陷双龙次洼SW20井烃源岩生烃史

Hydrocarbon Generation Modeling of Source Rocks in SW20 Well of Shuanglong Sub-sag,Lishu Depression

梨树断陷双龙次洼烃源岩生烃史模拟对研究区油气勘探具有重要意义。本文利用盆地模拟技术恢复研究区SW20井埋藏史、热史和烃源岩生烃史。研究证实:(1)梨树断陷双龙次洼沙河子组和营城组烃源岩有机质丰度较高,沙一段烃源岩有机质丰度最高,TOC平均值达到6.39%,沙二段次之,TOC平均为1.98%,有机质类型以Ⅱ型为主,营城组有机质丰度相对较低,TOC平均只有1.58%,有机质类型以Ⅲ型为主;两套烃源岩热解Tmax值介于430~463℃,现今Ro介于0.58%至1.17%之间,整体处于低熟—成熟阶段。(2)SW20井沉积地层埋藏史、热史和烃源岩生烃史模拟结果显示,沙河子组烃源岩在113 Ma进入生油门限,进入中等成熟阶段的时间为103 Ma,93 Ma进入晚成熟阶段;营城组烃源岩则在110 Ma进入生油门限,大约在100 Ma进入中等成熟阶段,65 Ma进入晚成熟阶段。在65 Ma左右,盆地构造格局发生变化,地层抬升,地层温度转而持续下降,烃源岩热演化进程趋于停滞。

Hydrocarbon generation modeling of source rocks in Shuanglong sub-sag of Lishu Fault Depression is of great significance to oil and gas exploration in the study area.This study applies basin modeling to recover the burial history,thermal history and hydrocarbon generation process of source rocks in the SW20 well.The results demonstrate that:(1)the organic matter abundance of source rocks of Shihezi and Yingcheng Formations in Shuanglong sub-sag of Lishu Fault Depression is relatively high,the organic matter abundance of source rocks of Sha 1 layer is the highest,with an average TOC of 6.39%,and the second section of Sha 2 layer is second,with an average TOC of 1.98%,and the organic matter type is dominated by Type II.The organic matter fraction of Yingcheng Formation is comparatively low,with an average TOC of only 1.58%,and the organic matter type is dominated by Type III;The two sets of source rocks have pyrolytic Tmax values ranging from 430℃to 463℃,with current Ro is between from 0.58%to 1.17%,which is in the low-maturity-mature stage.(2)The modeling results of burial history,thermal history and hydrocarbon generation of source rocks in SW20 well show that the source rocks of Shahezi Formation enter the oil production threshold at 113 Ma,and enter the medium maturity stage at 103 Ma,and enter the late maturity stage at 93 Ma;The source rocks of the Yingcheng Formation,on the other hand,enter the oil-generating threshold at 110 Ma,enter the middle maturity stage at 100 Ma,and enter into the late maturity stage at 65 Ma.Due to the uplifting,the geotemperature continuously decreases and hydrocarbon generation tend to be absent after 65 Ma.