辽河坳陷大民屯凹陷沙河街组四段页岩油富集资源潜力评价

Potential evaluation of enriched shale oil resource of Member 4 of the Shahejie Formation in the Damintun Sag,Liaohe Depression

页岩油具有高密度、高粘度以及低孔、低渗的特征,开采难度较大,因此对资源丰度相对较高、开采难度相对较小的富集资源进行评价十分必要。利用热解烃S1与有机碳含量(TOC)的"三分性"关系确定TOC大于4%为靶区页岩油富集资源划分标准。热解烃S1存在轻、重烃损失现象,在利用其进行资源评价前,需进行轻烃、重烃恢复。通过对比分析,发现抽提后页岩样品的裂解烃S2普遍降低,说明S2中包括一部分残留烃,而该部分残留烃在氯仿抽提过程中已被去除。利用抽提前、后S2的差值ΔS2对S1进行重烃恢复,重烃恢复系数随成熟度的增大而增大。假设页岩在排烃过程中轻烃和重烃等比例排出,利用生烃动力学原理对页岩生成各烃类组分的比例进行评价,进而根据该比例对S1进行轻烃恢复,轻烃恢复系数随着成熟度的增大呈先减小后增大的趋势。在测井评价页岩有机质非均质性(TOC和S1)的基础上,对富集资源进行划分,并利用S1的轻烃、重烃恢复结果,对页岩油富集资源进行资源评价。渤海湾盆地辽河坳陷大民屯凹陷E2s4(2)亚段页岩油富集资源量约为2.2×108t。

Recovery efficiency of shale oil is low due to high density, high viscosity, low porosity and low permeability, and it is necessary to evaluate the resource potential of the enriched resources that are high in resource abundance and low in exploitation difficulty. TOC over 4% is taken as the criteria for classification of enriched shale oil resource according to the triple-division relationship between S1 and TOC. Because of the light and heavy hydrocarbon loss in S1, S1 should be corrected before it is used to evaluate the resource potential. Comparative analysis shows that S2 decreases when the shale sample is extracted by chloroform, indicating that there are some residual hydrocarbons in S2 but they have been elimina- ted by extracting process. The distinction AS2 is used to correct the heavy hydrocarbon of S1, and the correction coefficient increases with the increase of maturity. Assuming that the light and heavy hydrocarbons expel at the same rate during the hydrocarbon expulsion process, the ratio calculated with hydrocarbon generation kinetics theory is used to correct the light hydrocarbon of S~. With the increase of maturity, the correction coefficient of light hydrocarbons first decreases and then increases. On the basis of evaluating the organic heterogeneity by logging, the enriched shale oil resource is classified, and its potential is evaluated by using the corrected Sa. The potential enriched shale oil resource is about 2.2 ×10^8t in E2s4（2） sub-member in the Damintun Sag,Liaohe Depression,Bohai Bay Basin.