塔里木盆地顺北地区不同断裂带油气充注能力表征研究与实践

Study and practice of characterizing hydrocarbon charging capacity of different fault zones,Shunbei area,Tarim Basin

沿走滑断裂带分布的中、下奥陶统碳酸盐岩油气藏,是塔里木盆地顺北地区勘探开发的主要目标,其地质储量丰富,开发前景广阔。走滑断裂带不同部位油气充注效率差异性较大,如何精准评价与描述充注效率优势部位,加快规模增储上产,提升勘探开发效率与效益,已成为制约顺北地区高效勘探开发的关键。基于顺北地区1号和5号断裂带“断层-储层”关系研究,首次探讨了影响顺北走滑断裂带油气充注效率的主要因素,包括断裂带内部结构、局部应变强度和现今地应力的大小及方向,并据此提出了“充注体”概念,进而半定量评价了断裂带不同部位垂向油气输导强度。该评价方法目前已成功应用在顺北地区5号断裂带上,评价结果与实际生产数据高度吻合。该方法不仅为断裂带分段评价和油气垂向输导“高速通道”的描述提供了有力的理论支撑,而且对顺北地区快速规模增储、实现稀井高产具有重要意义。

The Middle-Lower Ordovician carbonate reservoirs along strike-slip fault zones in the Shunbei area,Tarim Basin,are hydrocarbon bearing and have been the main targets of exploration and development for oil and gas.However,hydrocarbon charging efficiency at difference parts of the zones varies greatly,posing challenge for accurately evaluating and describing the dominant parts of charging,which in turn determines the efficiency and scale of exploration and development in the Shunbei area.To tackle the problem,this study is focused on the relationship between the faults and reservoirs in two of the fault zones(No.1 and 5)to discuss for the first time the main factors affecting the hydrocarbon charging efficiency in the zones that are reflected through the internal structure of the zones,the local strain intensity as well as the size and direction of the present in-situ stress.Based on the study,the concept of“charging body”is proposed and implemented to semi-quantitatively determine the vertical transport of hydrocarbons at different parts of the zones with results fitting well with the actual production data.This method not only provides strong theoretical support for segmental assessment of the zones and description of“high-speed channels”for vertical hydrocarbon migration,but also serves as a guidance to rapidly increasing reserves and promoting production with less wells in the Shunbei area.