Fracturing Technologies for Horizontal Wells in the Second-Class Shale Oil Reservoirs of the Lower Sweet Spot Areas in Jimusar

Technical research was carried out to enhance fracture control in fracturing with tight spacing and boost longitudinal production by cross layer fracturing in thin interbeddings. The research aims to address the difficult enhancement of horizontal well production induced by low fluidity and limited fracture height in beddings of the shale oil reservoirs in Jimusaer, Junggar Basin, and improve the production in the second-class shale oil reservoirs of the lower sweet spot areas in this region. The technique of fracturing with tight spacing was studied, with the average inter-cluster spacing reduced to 13.6 m, greatly strengthening the fracture control in shale oil reservoirs. The displacement and gel amount during vertical well fracturing were increased, and the feasibility of cross layer fracturing in the second-class reservoirs of the lower sweet spot areas was verified. As a result, the key technologies of cross layer fracturing, featured by large displacement (12–14 m³/min) in horizontal wells, multi-slug pumping of gel and slick water, proppant integrating medium and small particle sizes, and large sand addition (2.7 m³/m), were developed to provide strong support against the turning fractures in beddings.The annual cumulative oil production of the horizontal test wells in the second-class reservoirs achieved 9 183 t, more than three times that of previous horizontal wells.The field test demonstrates that the technologies can enlarge the fracturing volume in horizontal wells.The research results show that the cross layer fracturing with tight spacing for horizontal wells can solve the production problem of multiple thin oil layers in the second-class reservoirs and provide a new technical approach for the fracturing production of horizontal wells in such reservoirs.