油页岩原位注蒸汽开采油气中试与多模式原位热采技术的适用性分析

Pilot test of in-situ steam injection for oil and gas production from oil shale and applicability of multi-mode in-situ thermal recovery technology

油页岩是中国储量巨大的重要战略资源,也是国际公认的重要非常规石油资源。对油页岩进行地下原位干馏是目前实现其大规模工业开发的唯一可行技术方案。太原理工大学于2010年获得油页岩原位注蒸汽开采油气技术(MTI)的发明专利授权。基于MTI技术原理,对大尺寸油页岩试件实施原位注蒸汽开采油气的中试实验,并对多模式油页岩原位干馏技术的适用性进行分析。研究结果表明:(1)在实施油页岩原位多井水力压裂连通过程中,最高注水压力仅为地应力的41%,裂缝起裂扩展压力低。(2)蒸汽对流传热方式具备很高的传热效率,有机质热解迅速,蒸汽携带油气快速从生产井产出。同时,通过选择开启或关闭井组钻孔阀门的方式,实时调整蒸汽的流量和流向,灵活控制油页岩目标加热热解区域,实现了蒸汽的科学调配。(3)在油页岩原位注蒸汽正常运行过程中,蒸汽的注入压力仅约为自重应力的1/4,蒸汽锅炉长期低负载运行。(4)油页岩原位热解引发的地面沉降量很小,对地质环境危害小。(5)注汽热解区采出的含油率高达95%以上,总体原油采收率达到67.3%,充分证明利用MTI技术原位注蒸汽热解油页岩可达到较高的原油采收率。(6)所得油页岩油中轻质油品的占比达到72.51%;H;在热解气体中的比例占据绝对优势,体积含量高达68.87%。(7)注蒸汽热解区的顶、底板油页岩层热解不充分,裂隙发育不明显,成为良好的防渗隔热层。(8)MTI技术与其他油页岩原位热采技术相比,其在技术流程和经济性方面具有明显优势,具备广阔的商业开发应用前景。

Oil shale is an important strategic resource with huge reserves in China, and it is also an internationally recognized alternative energy source for crude oil. It has been fully proved that in-situ retorting of oil shale is the only feasible technical solution to realize its large-scale industrial development. Taiyuan University of Technology obtained an invention patent authorization of oil shale in-situ steam injection(MTI) for oil and gas productionin in 2010. Based on the principle of MTI technology, a pilot test of in-situ steam injection for oil and gas production was carried out on large-size oil shale specimens, and the applicability of multi-mode oil shale in-situ retorting technology was also analyzed. The results show that:(1) In the process of oil shale in-situ multi-well hydraulic fracturing, the maximum water injection pressure is only 41% of the in-situ stress, and the fracture initiation and propagation pressure is low.(2) The steam convection heat transfer method has high heat transfer efficiency, organic matter pyrolyzes quickly, and steam carrying oil and gas comes quickly from the production well. Meanwhile, by opening or closing the drilling valves of the well group, the flow and direction of steam can be adjusted in real time, and the target heating pyrolysis area of the oil shale can be flexibly controlled to realize the scientific deployment of steam.(3) During the normal operation of in-situ steam injection into oil shale, the steam injection pressure is only about 1/4 of the self weight stress, and the long-term operation load of steam boiler is low.(4) The land subsidence caused by in-situ pyrolysis of oil shale is very small, resulting in little harm to the geological environment.(5) The recovery oil content of the steam injection pyrolysis area is more than 95%, and the overall oil recovery rate reaches 67.3%, which has fully proved that the in-situ steam injection pyrolysis of oil shale by MTI technology can achieve high oil recovery.(6) The proportion of light oil products in the obtained shale oil is 72.51%;the proportion of H;in pyrolysis gas is absolutely dominant, and its volume content is as high as 68.87%.(7) The pyrolysis of the top and bottom oil shale in the steam injection pyrolysis area is insufficient, and the fracture development is not obvious, which has become a good anti-seepage and thermal insulation layer.(8) Compared with other oil shale in-situ thermal recovery technologies, MTI technology has obvious advantages in technical process and cost saving, and broad prospects in commercial development and application.