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尽管塔里木盆地石炭系富含有机质且已发现其生成的原油,但关于石炭系烃源岩热演化研究却很薄弱。根据基础地质资料、古地温梯度和实测镜质体反射率数据,本文定量模拟了塔里木盆地6口典型井的石炭系烃源岩热演化史和这套烃源岩底界、顶界在二叠纪末期、三叠纪末期、白垩纪末期及现今成熟度的平面分布规律。塔北隆起南部、塔西南坳陷和阿瓦提凹陷在石炭—二叠纪作为沉降中心接受了巨厚的沉积物,造成这些地区石炭系烃源岩底界成熟度在二叠纪末期达到0.9%~1.3%(中—高成熟),顶界为0.5%~0.9%(低—中成熟),成为有利生油区。中生代时期,塔里木盆地中、东部长期处于沉降状态,石炭系烃源岩处于成熟演化阶段。白垩纪末期,塔中低凸起和满加尔凹陷的石炭系底界成熟度为0.7%~0.9%(中成熟),顶界为0.5%~0.7%(低成熟);而塘古孜巴斯坳陷底界成熟度为0.9%~1_1%(中—高成熟),顶界为0.7%~0.9%(中成熟)。受羌塘地体、拉萨地体、印度板块分别与欧亚板块南缘碰撞远程效应的影响,塔西南坳陷和巴楚隆起在中生代一直处于隆升剥蚀状态,烃源岩热演化进入停滞状态。新生代以来,塔西南坳陷和阿瓦提凹陷演化为前陆盆地,再次接受了巨厚沉积物,致使石炭系烃源岩快速成熟演化,底一顶界成熟度现今已超过2.0%,进入干气阶段。满加尔凹陷石炭系烃源岩自石炭纪至今一直处于成熟演化阶段,现今达到最大,为0.8%~1.0%。另外,热史研究表明塔西南坳陷和阿瓦提凹陷石炭系烃源岩具有二次生烃潜力。本研究不仅丰富了塔里木盆地石炭系烃源岩热史研究成果,而且对油气勘探与开发具有重要的指导意义。
Although the Carboniferous in the Tarim Basin is rich in organic matter and its crude oil has been discovered, the study on the thermal evolution of Carboniferous source rocks is very weak. According to the basic geological data, the paleogeothermal gradient and the measured vitrinite reflectance data, this paper quantitatively simulates the thermal evolution history of the Carboniferous hydrocarbon source rocks in six typical wells in the Tarim Basin and the source rock subfacies, End Plains, Late Triassic, Cretaceous and the current maturity plane distribution. The southern Thaeta Uplift, the southwestern Tarim Basin and the Awati Depression received massive sediments in the Carboniferous-Permian subsidence center, resulting in the maturity of the Carboniferous source rocks in these areas reaching 0.9 at the end of the Permian % ~ 1.3% (medium - high maturity), and the top is 0.5% ~ 0.9% (low - middle maturity). During the Mesozoic, the middle and eastern Tarim Basin were in a state of subsidence for a long period of time, and the Carboniferous source rocks were in the mature evolution stage. At the end of the Cretaceous, the maturity of the Carboniferous bottom boundary between the Tazhong low and Manjar sags ranges from 0.7% to 0.9% (medium maturity) and the top ranges from 0.5% to 0.7% (low maturity) The bottom of the depression has a maturity of 0.9% -1 1% (medium-high maturity) and a top 0.7% -0.9% (medium maturity). Influenced by the collision remote effect between the Qiangtang terrane, Lhasa terrane and India plate and the southern edge of Eurasian plate, the southwestern Tarim basin and the Bachu uplift have been uplifted and eroded in the Mesozoic, and the thermal evolution of source rocks has reached a standstill . Since the Cenozoic, the Tashannan Depression and the Awati Depression have evolved into foreland basins, again accepting thick sediments, resulting in the rapid maturation of the Carboniferous source rocks. The maturity of the top-bottom boundary has now exceeded 2.0% Dry gas stage. The Carboniferous source rocks in Manjiaer Depression have been in the mature evolution stage since the Carboniferous up to now, reaching the maximum at 0.8% -1.0%. In addition, thermal history studies indicate that the Carboniferous source rocks in the southwestern Tarim Basin and the Awati Sag have secondary hydrocarbon generation potentials. This study not only enriches the research results of the thermal history of Carboniferous hydrocarbon source rocks in the Tarim Basin, but also has important guiding significance for oil and gas exploration and development.