【摘要】 深层原油保存能力的评价制约着原油勘探的深度下限。为了评价不同性质原油保存能力,以不同性质原油与灰岩介质为对象,通过热模拟实验产物分析,参照基础理论,提出了原油保存指数概念,并以等效镜质体反射率为桥梁,对原油保存能力进行评价。原油保存能力主要受热演化程度控制,等效镜质体反射率VR_o<1.2%,VR_o=1.2%～2.0%和VR_o>2.0%的缓慢裂解、快速裂解和极限裂解阶段保存指数分别降低0.230,0.324和0.350。原油组成的差异决定不同性质原油具有不同的保存能力。轻质油早期保存能力较强,进入裂解门限后,保存能力迅速降低;重质油因较多的杂原子和侧链,致使保存能力呈现早期弱、晚期强的特点,但保存下来多是固体沥青等大分子缩聚物。根据热模拟实验结果预测了塔里木盆地满西地区深层液态烃的保存下限,满西地区奥陶系原油勘探下限深度为8 200 m。更多还原

【Abstract】 An evaluation of deep crude oil preservation ability identifies the depth limit of crude oil exploration. Thermal simulation products of crude oils with different properties and limestone media were analyzed and combined with oil cracking theory to develop an oil preservation index(OPI). The simulated temperature/thermal evolution degree is the key factor affecting crude oil preservation. OPI decreased by 0.230, 0.324 and 0.350, respectively, with VR_o increasing from <1.2%, 1.2%-2.0% to >2.0%. Crude oil with different properties often shows different preservation ability. Light oil, rich in saturated hydrocarbons with fewer branched chains and higher H/C atom ratio, shows stronger preservation ability in the early stage. But once the cracking threshold is reached, rapid cracking occurs. Heavy oil has more branched chains and heteroatoms due to the presence of non-hydrocarbons and asphaltene undergoes faster cracking in the early stage, and shows higher stability in the later stage. But most of the residue is solid bitumen and other macromolecule condensates. The depth limit of crude oil preservation was predicted by using the experimental results of thermal simulation in Manxi region, Tarim Basin. The depth limit of crude oil exploration in the southern Manxi region is 8 200 m.更多还原