致密储层缝内暂堵转向压裂工艺技术

Intrafracture temporary plugging and diversion fracturing technology suitable for tight reservoirs

随着油气田勘探开发的不断深入,非常规致密油气藏已经成为油田增储上产的主要研究对象,该类型储层渗透率低(<0.1×10^(−3)μm^(2))、两向应力差值大(>10 MPa),单纯依靠大排量、大液量改造以形成缝网的难度较大,需通过缝内暂堵转向压裂技术进一步增大净压力,提高裂缝复杂程度。暂堵剂类型的优选和用量设计是决定复杂缝网形成的关键,进而影响压裂井的改造效果。优选水基温控溶解型暂堵剂,综合考虑了暂堵剂封堵厚度、动态裂缝高度、微裂缝条数及宽度等参数,形成了暂堵剂用量设计方法。现场共计应用了11口井37层,其中28层投放暂堵剂后等排量下压力上涨0.5~7.0 MPa,有效率达到75.7%,实现了缝内暂堵转向造缝网的目的,为后期致密储层改造提供了理论依据,实现了致密油气藏的有效动用。

As oil and gas exploration and development advances continuously,unconventional tight oil and gas reservoirs have already become the main objects for oilfields to realize reserve and production increase.This type of reservoir is characterized by low permeability(<0.1×10^(−3)μm^(2))and large bidirectional stress difference(>10 MPa),so it is difficult to induce fracture network only based on the stimulation of large displacement and liquid rate.To this end,intrafracture temporary plugging and diversion fracturing technology is needed to increase the net pressure further and improve the fracture complexity.The type selection and dosage design of temporary plugging agent is the determinative key to the formation of complex fracture network and consequently influences the stimulation effect of fracturing wells.The water based temperature control dissolution type temporary plugging agent was selected,and the plugging thickness of temporary plugging agent,the height of dynamic fractures and the quantity and thickness of micro fractures were taken into consideration comprehensively to form the method for the dosage design of temporary plugging agent.It has been totally applied in 37 layers of 11 wells,among which,the pressure of 28 layers under the same displacement is increased by 0.5-7.0 MPa after the injection of temporary plugging agent and the efficiency is up to 75.7%.Thus,the goal of intrafracture temporary plugging and diversion fracturing network is reached.The research results provide theoretical basis for the later tight reservoir stimulation,so as to achieve the effective production of tight oil and gas reservoirs.