从烃源岩测井评价结果看冀中坳陷饶阳凹陷勘探前景

Suggestion of Exploration Prospect in Raoyang Sag of Jizhong Depression from the Logging Evaluation Results of Source Rock

常规的烃源岩有机地球化学分析评价方法往往受样品分析数量和岩心质量的制约,很难真实地揭示烃源岩的空间分布特征,而采用测井和地球化学分析相结合的方法,却能够通过纵向连续的高分辨率测井信息快速准确地计算出地层的有机碳含量,识别出烃源岩在空间上的变化特征。依据湖相泥岩TOC—IH关系将冀中坳陷烃源岩划分为3个级别：TOC≥2%为优质烃源岩,TOC=1%~2%为中等烃源岩和TOC=0.5%~1%为差烃源岩。冀中坳陷饶阳凹陷古近系湖相烃源岩在平面上和剖面上受沉积相带的控制,从盆地边缘到湖盆中心,烃源岩从薄互层向集中大套发育段变化,优质烃源岩集中发育于洼槽区。通过烃源岩测井评价,并结合资源潜力和分布状况分析,认为潜山、古近系深层岩性、中浅层复杂断块和新近系浅层岩性构造勘探领域是饶阳凹陷深化勘探的重要方向。

Since the number of rock samples and quality of core constrain the conventional geochemical measurement and hydrocarbon-generated evaluation for source rock,it is difficult to reveal the real spatial distribution of source rock.The logging method associated with the geochemical analysis can carry out the prediction of total organic carbon TOC of source rock and spatial distribution by mean of the high vertical resolution log data.Based on relationship between TOC and hydrogen index IH,the lacustrine source rock in the Jizhong depression can be divided into three class as follows： High quality source rock with TOC2%,good source rock with TOC=1%-2%,and poor source rock with TOC=0.5%-1%,respectively.The lateral and vertical distribution of paelocene lacustrine source rock was controlled by depositional facies,and the high quality source rock mainly was developed in the depositional center.From the margin to the basinal center,the thickness of the high quality source rock is various from thin to thick.According to evaluation of logging data,distribution and prospect of potential resource,the future favorable exploration area should focus on the buried hill,Paleocene deep lithological layer,shallow and middle complex fault-block structure in the Raoyang sag.