松辽盆地古龙页岩油原位成藏理论认识及勘探开发实践

松辽盆地古龙地区青山口组一段—青山口组二段页岩油资源丰富,实现了具有战略意义的勘探突破,开发先导试验取得初步成果,展现了广阔的页岩油勘探开发前景。古龙页岩油为典型的原生源储原位油藏,其源储关系、运移特征、聚集动力、边界条件等成藏特征和流体相态相变机理、微米—纳米级缝孔体系梯次输运机制等渗流特征与致密油、夹层型、混积型页岩油具有明显区别,为实现高效开发,形成了以"箱式开发"为核心的关键技术系列,并初见成效。页岩中与黏土矿物共生的层状藻类体生烃后,形成以有机孔为主的孔缝体系,受毛细管力、黏滞力等作用的综合影响,油气分子未发生运移而原地超压保存,形成规模分布、相对独立、具有不同压力系统及流体性质的微米—纳米级含油孔隙集合体,构成原生源储原位油藏。增加人工裂缝复杂程度,使不同压力系统的含油孔隙逐步达到流体启动压力、孔隙内赋存的原油梯次流向裂缝网络,是实现古龙页岩原位油藏开发、油井保持长期稳产的核心。勘探开发实践推动形成了以"有机相+应力级差"为核心的箱体划分技术、以"可动油含量"为核心的黄金靶体优化技术和箱体内"一次布井、多靶叠置、立体交错、整体动用"一体优化技术,应用成效明显。古龙页岩油原位成藏理论认识丰富了传统石油地质理论,必将引领世界原位型页岩油理论发展,将页岩油革命推向新的高度。古龙页岩油的规模效益开发,对保障国家能源战略安全、促进区域经济社会发展具有重要战略意义。

In-situ accumulation theory and exploration&development practice of Gulong shale oil in Songliao Basin

Shale oil resources are rich in Member 1 and 2 of Qingshankou Formation in the Gulong area of Songliao Basin;a breakthrough of strategic importance has been achieved in oil exploration,and preliminary achievements have been made in the pilot test of reservoir development,showing a broad prospect for shale oil exploration and development.Gulong shale oil is a typical primary reservoir in source strata,characterized with source-reservoir assemblage;it is obviously different from tight oil,sandwich-type and hybrid depositional shale oil in terms of the reservoiring characteristics such as source-reservoir relationship,migration features,accumulation dynamics and boundary conditions,as well as the seepage characteristics involving the phase change mechanism of fluid phase behavior and the staged transportation mechanism of the micro-nano fracture-pore system.In order to effectively achieve the target,a series of key exploration and development technologies with a focus on“box-type reservoir development”has been established,and initial success has been achieved.After hydrocarbon generation of the lamalginite associated with clay minerals in shale oil,the fracture-pore system dominated by organic pores has been formed.Under the joint action of capillary force and viscous force,oil and gas molecules can not migrate,and is preserved in situ under overpressure.Thus,the micro-nano oil-bearing pore aggregates that are distributed in a large scale,relatively independent and have different pressure systems and fluid properties have been formed,thus constituting the primary reservoir in source strata.The key to achieve the development of primary reservoir in the source strata of Gulong shale and maintain stable production of oil well for a long time is to increase the complexity of artificial fractures,and make the oil-bearing pores of different pressure systems gradually reach the fluid start-up pressure and the crude oil occurred in pores flow to the fracture network step by step.Actually,the exploration and development practice has promoted the formation of box division technology with“organic phase+stress step”as the core,the gold target optimization technology with“movable oil content”as the core,and the integrated optimization technology of“one-time well layout,multi-target stacking,three-dimensional interleaving and overall employment”,which has achieved obvious application results.The theoretical understanding of oil reservoir formation in the source strata of Gulong shale enriches the traditional petroleum geology theory,which will inevitably lead the development of theories regarding shale oil in source strata in the whole world and push the shale oil revolution to a new height.Furthermore,the large-scale efficient development of Gulong shale oil is of strategic significance for safeguarding the national energy strategy,promoting the construction of comprehensive international energy companies in China and boosting regional economic and social development.