页岩油气增强型体积压裂成缝机制和关键技术OA

There are abundant shale oil and gas resources in China,but the geological and engineering conditions are complex.Existing fracturing technologies are mainly applicable to brittle shales with natural fractures and small stress differences,exhibiting limited adaptability,significant production fluctuations,low proven rates,and great difficulty for benefit development.Focusing on the fundamental development characteristics of weak-plane structures such as bedding and lamination in shale formations,this paper clarifies the fracture formation mechanisms in the reservoirs with micro-scale weak planes developed,proposes a production enhancement principle centered on"regulating net pressure to the critical fracturing pressure of weak planes",and develops enhanced shale oil/gas volume fracturing technologies with"stepwise pumping rate,near-wellbore fractures control for more far-wellbore fractures propagation stimulation"technique and efficient variable-viscosity slickwater based fracturing fluid system as the core.The following results are obtained.First,the precise regulation of net pressure to fracture weak planes such as bedding can significantly expand effective stimulated reservoir volume,and enhance fracture complexity,so as to achieve production multiplication and technical-economic resilience improvement.Second,the"stepwise pumping rate,near-wellbore fractures control for more far-wellbore fractures propagation stimulation"technique can effectively deal with the challenges to brittle shale,such as difficult fracture propagation in far-wellbore zones,excessive complexity near the wellbore,and casing deformation,thereby increasing well-controlled reserve producing degree.Third,the innovative technical system characterized by"fracturing bedding to promote complexity,controlling near-wellbore fractures for more long far-wellbore fractures propagation,and boosting production by variable-viscosity slickwater and ESRV expansion"has been widely applied,showcasing China's efficient development capabilities of Estimated Ultimate Recovery(EUR)(2-3)×108 m3 for shale gas and(3-5)×104 t for shale oil per kilometer horizontal sections.In conclusion,the innovative implementation of the efficient variable-viscosity slickwater based enhanced volume fracturing technology based on shale fracturing mechanisms and control methods is crucial to the breakthrough in shale oil and gas production in China,and provides fundamental theoretical basis and technical pathways for advancing shale oil and gas revolution.